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Sample records for appendage scaffolds alternate

  1. [Alternative scaffold proteins].

    Science.gov (United States)

    Petrovskaia, L E; Shingarova, L N; Dolgikh, D A; Kirpichnikov, M P

    2011-01-01

    Review is devoted to the challenging direction in modem molecular biology and bioengineering - the properties of alternative scaffold proteins (ASP) and methods for obtaining ASP binding molecules. ASP molecules incorporate conservative protein core and hypervariable regions, providing for the binding function. Structural classification of ASP includes several types which differ also in their molecular targets and potential applications. Construction of artificial binding proteins on the ASP basis implies a combinatorial library design with subsequent selection of specific binders with the use of phage display or the modem cell-free systems. Alternative binding proteins on non-immunoglobulin scaffolds find broad applications in different fields ofbiotechnology and molecular medicine.

  2. Percutaneous methods of left atrial appendage exclusion: an alternative to the internist.

    Science.gov (United States)

    Le, Duong L; Khodjaev, Soidjon D; Morelli, Remo L

    2014-01-01

    Thromboembolic stroke from the left atrial appendage (LAA) is the most feared complication in patients with atrial fibrillation (AF). The cornerstone for the management of chronic non-valvular AF is stroke reduction with oral anticoagulation (OAC). However, poor compliance, maintaining a narrow therapeutic window, and major side effects such as bleeding have severely limited their use, which creates a therapeutic dilemma. As much as 20% of AF patients are not receiving OAC due to contraindications and less than half of AF patients are not on OAC due to reluctance of the prescribing physician and/or patient non-compliance. Fortunately, over the past decade, there have been great interests in providing an alternative strategy unbeknownst to the practicing internist. The introduction of percutaneous approaches for LAA occlusion has added a different dimension to the management of chronic AF in patients with OAC intolerance. Occlusion devices such as the Amplatzer Cardiac Plug and WATCHMAN device are currently being investigated for stroke prophylaxis. More recently, the LARIAT device may provide an alternative means for potential stroke prophylaxis without the need for short-term post-procedural OAC. We aim to review the current literature and bring attention to an alternative strategy for high-risk AF patients intolerant to OAC.

  3. Scaffolding conversations using augmentative and alternative communication (AAC

    Directory of Open Access Journals (Sweden)

    Jane Sara Remington-Gurney

    2013-08-01

    Full Text Available Non speech methods of communication, such as the use of gesture and signing along with pointing or indicating icons on a screen or display is known collectively as Augmentative and Alternative Communication (AAC. This paper is not research driven but does explore the critical role of the speaking communication partner in enabling and empowering the user of AAC to have a voice in social interactions. Transcription analysis is used to examine what communication partners do in three recorded interviews with people who have difficulty with spoken language. It is proposed that there would be more efficient and inclusive discourses if more communication partners through in-service and pre-service training, were comfortable with scaffolding techniques.

  4. Sol-gel assisted fabrication of collagen hydrolysate composite scaffold: a novel therapeutic alternative to the traditional collagen scaffold.

    Science.gov (United States)

    Ramadass, Satiesh Kumar; Perumal, Sathiamurthi; Gopinath, Arun; Nisal, Anuya; Subramanian, Saravanan; Madhan, Balaraman

    2014-09-10

    Collagen is one of the most widely used biomaterial for various biomedical applications. In this Research Article, we present a novel approach of using collagen hydrolysate, smaller fragments of collagen, as an alternative to traditionally used collagen scaffold. Collagen hydrolysate composite scaffold (CHCS) was fabricated with sol-gel transition procedure using tetraethoxysilane as the silica precursor. CHCS exhibits porous morphology with pore sizes varying between 380 and 780 μm. Incorporation of silica conferred CHCS with controlled biodegradation and better water uptake capacity. Notably, 3T3 fibroblast proliferation was seen to be significantly better under CHCS treatment when compared to treatment with collagen scaffold. Additionally, CHCS showed excellent antimicrobial activity against the wound pathogens Staphylococcus aureus, Bacillus subtilis, and Escherichia coli due to the inherited antimicrobial activity of collagen hydrolysate. In vivo wound healing experiments with full thickness excision wounds in rat model demonstrated that wounds treated with CHCS showed accelerated healing when compared to wounds treated with collagen scaffold. These findings indicate that the CHCS scaffold from collagen fragments would be an effective and affordable alternative to the traditionally used collagen structural biomaterials.

  5. Effect of Scaffolding on Helping Introductory Physics Students Solve Quantitative Problems Involving Strong Alternative Conceptions

    CERN Document Server

    Lin, Shih-Yin

    2016-01-01

    It is well-known that introductory physics students often have alternative conceptions that are inconsistent with established physical principles and concepts. Invoking alternative conceptions in quantitative problem-solving process can derail the entire process. In order to help students solve quantitative problems involving strong alternative conceptions correctly, appropriate scaffolding support can be helpful. The goal of this study is to examine how different scaffolding supports involving analogical problem solving influence introductory physics students' performance on a target quantitative problem in a situation where many students' solution process is derailed due to alternative conceptions. Three different scaffolding supports were designed and implemented in calculus-based and algebra-based introductory physics courses to evaluate the level of scaffolding needed to help students learn from an analogical problem that is similar in the underlying principles but for which the problem solving process i...

  6. Effect of scaffolding on helping introductory physics students solve quantitative problems involving strong alternative conceptions

    Science.gov (United States)

    Lin, Shih-Yin; Singh, Chandralekha

    2015-12-01

    It is well known that introductory physics students often have alternative conceptions that are inconsistent with established physical principles and concepts. Invoking alternative conceptions in the quantitative problem-solving process can derail the entire process. In order to help students solve quantitative problems involving strong alternative conceptions correctly, appropriate scaffolding support can be helpful. The goal of this study is to examine how different scaffolding supports involving analogical problem-solving influence introductory physics students' performance on a target quantitative problem in a situation where many students' solution process is derailed due to alternative conceptions. Three different scaffolding supports were designed and implemented in calculus-based and algebra-based introductory physics courses involving 410 students to evaluate the level of scaffolding needed to help students learn from an analogical problem that is similar in the underlying principles involved but for which the problem-solving process is not derailed by alternative conceptions. We found that for the quantitative problem involving strong alternative conceptions, simply guiding students to work through the solution of the analogical problem first was not enough to help most students discern the similarity between the two problems. However, if additional scaffolding supports that directly helped students examine and repair their knowledge elements involving alternative conceptions were provided, e.g., by guiding students to contemplate related issues and asking them to solve the targeted problem on their own first before learning from the analogical problem provided, students were more likely to discern the underlying similarities between the problems and avoid getting derailed by alternative conceptions when solving the targeted problem. We also found that some scaffolding supports were more effective in the calculus-based course than in the algebra

  7. Annealing free, clean graphene transfer using alternative polymer scaffolds

    Science.gov (United States)

    Wood, Joshua D.; Doidge, Gregory P.; Carrion, Enrique A.; Koepke, Justin C.; Kaitz, Joshua A.; Datye, Isha; Behnam, Ashkan; Hewaparakrama, Jayan; Aruin, Basil; Chen, Yaofeng; Dong, Hefei; Haasch, Richard T.; Lyding, Joseph W.; Pop, Eric

    2015-02-01

    We examine the transfer of graphene grown by chemical vapor deposition (CVD) with polymer scaffolds of poly(methyl methacrylate) (PMMA), poly(lactic acid) (PLA), poly(phthalaldehyde) (PPA), and poly(bisphenol A carbonate) (PC). We find that optimally reactive PC scaffolds provide the cleanest graphene transfers without any annealing, after extensive comparison with optical microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, and scanning tunneling microscopy. Comparatively, films transferred with PLA, PPA, PMMA/PC, and PMMA have a two-fold higher roughness and a five-fold higher chemical doping. Using PC scaffolds, we demonstrate the clean transfer of CVD multilayer graphene, fluorinated graphene, and hexagonal boron nitride. Our annealing free, PC transfers enable the use of atomically-clean nanomaterials in biomolecule encapsulation and flexible electronic applications.

  8. Micro/Nano Multilayered Scaffolds of PLGA and Collagen by Alternately Electrospinning for Bone Tissue Engineering.

    Science.gov (United States)

    Kwak, Sanghwa; Haider, Adnan; Gupta, Kailash Chandra; Kim, Sukyoung; Kang, Inn-Kyu

    2016-12-01

    The dual extrusion electrospinning technique was used to fabricate multilayered 3D scaffolds by stacking microfibrous meshes of poly(lactic acid-co-glycolic acid) (PLGA) in alternate fashion to micro/nano mixed fibrous meshes of PLGA and collagen. To fabricate the multilayered scaffold, 35 wt% solution of PLGA in THF-DMF binary solvent (3:1) and 5 wt% solution of collagen in hexafluoroisopropanol (HFIP) with and without hydroxyapatite nanorods (nHA) were used. The dual and individual electrospinning of PLGA and collagen were carried out at flow rates of 1.0 and 0.5 mL/h, respectively, at an applied voltage of 20 kV. The density of collagen fibers in multilayered scaffolds has controlled the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. The homogeneous dispersion of glutamic acid-modified hydroxyapatite nanorods (nHA-GA) in collagen solution has improved the osteogenic properties of fabricated multilayered scaffolds. The fabricated multilayered scaffolds were characterized using FT-IR, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). The scanning electron microscopy (FE-SEM) was used to evaluate the adhesion and spreads of MC3T3-E1 cells on multilayered scaffolds. The activity of MC3T3-E1 cells on the multilayered scaffolds was evaluated by applying MTT, alkaline phosphatase, Alizarin Red, von Kossa, and cytoskeleton F-actin assaying protocols. The micro/nano fibrous PLGA-Col-HA scaffolds were found to be highly bioactive in comparison to pristine microfibrous PLGA and micro/nano mixed fibrous PLGA and Col scaffolds.

  9. Micro/Nano Multilayered Scaffolds of PLGA and Collagen by Alternately Electrospinning for Bone Tissue Engineering

    Science.gov (United States)

    Kwak, Sanghwa; Haider, Adnan; Gupta, Kailash Chandra; Kim, Sukyoung; Kang, Inn-Kyu

    2016-07-01

    The dual extrusion electrospinning technique was used to fabricate multilayered 3D scaffolds by stacking microfibrous meshes of poly(lactic acid-co-glycolic acid) (PLGA) in alternate fashion to micro/nano mixed fibrous meshes of PLGA and collagen. To fabricate the multilayered scaffold, 35 wt% solution of PLGA in THF-DMF binary solvent (3:1) and 5 wt% solution of collagen in hexafluoroisopropanol (HFIP) with and without hydroxyapatite nanorods (nHA) were used. The dual and individual electrospinning of PLGA and collagen were carried out at flow rates of 1.0 and 0.5 mL/h, respectively, at an applied voltage of 20 kV. The density of collagen fibers in multilayered scaffolds has controlled the adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. The homogeneous dispersion of glutamic acid-modified hydroxyapatite nanorods (nHA-GA) in collagen solution has improved the osteogenic properties of fabricated multilayered scaffolds. The fabricated multilayered scaffolds were characterized using FT-IR, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). The scanning electron microscopy (FE-SEM) was used to evaluate the adhesion and spreads of MC3T3-E1 cells on multilayered scaffolds. The activity of MC3T3-E1 cells on the multilayered scaffolds was evaluated by applying MTT, alkaline phosphatase, Alizarin Red, von Kossa, and cytoskeleton F-actin assaying protocols. The micro/nano fibrous PLGA-Col-HA scaffolds were found to be highly bioactive in comparison to pristine microfibrous PLGA and micro/nano mixed fibrous PLGA and Col scaffolds.

  10. Left atrial appendage occlusion

    Directory of Open Access Journals (Sweden)

    Ahmad Mirdamadi

    2013-01-01

    Full Text Available Left atrial appendage (LAA occlusion is a treatment strategy to prevent blood clot formation in atrial appendage. Although, LAA occlusion usually was done by catheter-based techniques, especially percutaneous trans-luminal mitral commissurotomy (PTMC, it can be done during closed and open mitral valve commissurotomy (CMVC, OMVC and mitral valve replacement (MVR too. Nowadays, PTMC is performed as an optimal management of severe mitral stenosis (MS and many patients currently are treated by PTMC instead of previous surgical methods. One of the most important contraindications of PTMC is presence of clot in LAA. So, each patient who suffers of severe MS is evaluated by Trans-Esophageal Echocardiogram to rule out thrombus in LAA before PTMC. At open heart surgery, replacement of the mitral valve was performed for 49-year-old woman. Also, left atrial appendage occlusion was done during surgery. Immediately after surgery, echocardiography demonstrates an echo imitated the presence of a thrombus in left atrial appendage area, although there was not any evidence of thrombus in pre-pump TEE. We can conclude from this case report that when we suspect of thrombus of left atrial, we should obtain exact history of previous surgery of mitral valve to avoid misdiagnosis clotted LAA, instead of obliterated LAA. Consequently, it can prevent additional evaluations and treatments such as oral anticoagulation and exclusion or postponing surgeries including PTMC.

  11. Pressure Shift Freezing as Potential Alternative for Generation of Decellularized Scaffolds

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    S. Eichhorn

    2013-01-01

    Full Text Available Background. Protocols using chemical reagents for scaffold decellularization can cause changes in the properties of the matrix, depending on the type of tissue and the chemical reagent. Technologies using physical techniques may be possible alternatives for the production grafts with potential superior matrix characteristics. Material and Methods. We tested four different technologies for scaffold decellularization. Group 1: high hydrostatic pressure (HHP, 1 GPa; Group 2: pressure shift freezing (PSF; Group 3: pulsed electric fields (PEF; Group 4: control group: detergent (SDS. The degree of decellularization was assessed by histological analysis and the measurement of residual DNA. Results. Tissue treated with PSF showed a decellularization with a penetration depth (PD of 1.5 mm and residual DNA content of . HHD treatment caused a PD of 0.2 mm with a residual DNA content of . PD in PEF was 0.5 mm, and the residual DNA content was . In the SDS group, PD was found to be 5 mm, and the DNA content was determined at . Conclusion. PSF showed promising results as a possible technique for scaffold decellularization. The penetration depth of PSF has to be optimized, and the mechanical as well as the biological characteristics of decellularized grafts have to be evaluated.

  12. Percutaneous left atrial appendage closure: current state of the art.

    Science.gov (United States)

    Jazayeri, Mohammad-Ali; Vuddanda, Venkat; Parikh, Valay; Lakkireddy, Dhanunjaya R

    2017-01-01

    The authors reviewed the seminal and more recent literature surrounding the major modalities for percutaneous left atrial appendage closure used in contemporary practice, with particular emphasis on safety and efficacy, technical challenges, and future developments. Along with the continued practice of surgical left atrial appendage closure, which has evolved substantially with the advent of clipping techniques, a number of percutaneous methods have been developed to close the left atrial appendage with endocardial, epicardial, and hybrid approaches. The last 18 months has seen the Food and Drug Administration approval of the WATCHMAN device for stroke prevention in the United States, the initiation of a randomized controlled trial to further examine the LARIAT device, and an increasing body of literature surrounding use of the AMPLATZER Amulet in Europe. Left atrial appendage closure is a promising alternative to systemic anticoagulation for stroke prevention in appropriate atrial fibrillation patients. The wealth of available data for the various modalities sheds light on the strengths and limitations of each, postprocedural complications and their management, and new areas for exploration. With a plethora of new devices on the horizon, it is a very exciting time in the field of 'appendage-ology' as we pursue new avenues to optimize care for atrial fibrillation patients.

  13. Possible role for cryoballoon ablation of right atrial appendage tachycardia when conventional ablation fails.

    Science.gov (United States)

    Amasyali, Basri; Kilic, Ayhan

    2015-06-01

    Focal atrial tachycardia arising from the right atrial appendage usually responds well to radiofrequency ablation; however, successful ablation in this anatomic region can be challenging. Surgical excision of the right atrial appendage has sometimes been necessary to eliminate the tachycardia and prevent or reverse the resultant cardiomyopathy. We report the case of a 48-year-old man who had right atrial appendage tachycardia resistant to multiple attempts at ablation with use of conventional radiofrequency energy guided by means of a 3-dimensional mapping system. The condition led to cardiomyopathy in 3 months. The arrhythmia was successfully ablated with use of a 28-mm cryoballoon catheter that had originally been developed for catheter ablation of paroxysmal atrial fibrillation. To our knowledge, this is the first report of cryoballoon ablation without isolation of the right atrial appendage. It might also be an alternative to epicardial ablation or surgery when refractory atrial tachycardia originates from the right atrial appendage.

  14. Identifying Differences in Diagnostic Skills between Physics Students: Students' Self-Diagnostic Performance Given Alternative Scaffolding

    CERN Document Server

    Cohen, Elisheva; Singh, Chandralekha; Yerushalmi, Edit

    2016-01-01

    "Self-diagnosis tasks" aim at fostering diagnostic behavior by explicitly requiring students to present diagnosis as part of the activity of reviewing their problem solutions. We have been investigating the extent to which introductory physics students can diagnose their own mistakes when explicitly asked to do so with different levels of scaffolding support provided to them. In our study in an introductory physics class with more than 200 students, the recitation classes were split into three different experimental groups in which different levels of guidance were provided for performing the self-diagnosis activities. We present our findings that students' performance was far from perfect. However, differences in the scaffolding in the three experimental groups (i.e. providing a correct solution and a self-diagnosis rubric) noticeably affected the resulting diagnosis.

  15. Retrieval of embolized left atrial appendage devices.

    Science.gov (United States)

    Fahmy, Peter; Eng, Lim; Saw, Jacqueline

    2016-09-28

    Percutaneous left atrial appendage (LAA) closure is gaining interest as an alternative option for prevention of strokes in patients with Atrial Fibrillation (AF), especially for those with contraindications to anticoagulation. Complications from these procedures are well described in the medical literature. LAA closures may lead to pericardial effusion, device-associated thrombus, and device embolization. Understanding the reasons for embolization, strategies to avoid embolization, and the techniques for retrieval of LAA devices (ACP/AMULET and WATCHMAN) should be appreciated by endovascular implanters. We describe two cases of LAA device embolization that were both successfully retrieved percutaneously and other percutaneous techniques to safely retrieve embolized LAA devices. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  16. Enhancement of skin wound healing with decellularized scaffolds loaded with hyaluronic acid and epidermal growth factor

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    Su, Zhongchun; Ma, Huan; Wu, Zhengzheng [Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Lab for Genetic Medicine of Guangdong Province, Jinan University, Guangzhou 510632 (China); Zeng, Huilan [Department of Hematology, The First Affiliated Hospital, Jinan University, Guangzhou 510632 (China); Li, Zhizhong [Department of Bone, The First Affiliated Hospital, Jinan University, Guangzhou 510632 (China); Wang, Yuechun; Liu, Gexiu [Department of Physiology, School of Medicine, Jinan University, Guangzhou 510632 (China); Xu, Bin; Lin, Yongliang; Zhang, Peng [Grandhope Biotech Co., Ltd., Building D, #408, Guangzhou International Business Incubator, Guangzhou Science Park, Guangzhou 510663, Guangdong (China); Wei, Xing, E-mail: wei70@hotmail.com [Institute of Biomedicine, National Engineering Research Center of Genetic Medicine, Key Lab for Genetic Medicine of Guangdong Province, Jinan University, Guangzhou 510632 (China)

    2014-11-01

    Current therapy for skin wound healing still relies on skin transplantation. Many studies were done to try to find out ways to replace skin transplantation, but there is still no effective alternative therapy. In this study, decellularized scaffolds were prepared from pig peritoneum by a series of physical and chemical treatments, and scaffolds loaded with hyaluronic acid (HA) and epidermal growth factor (EGF) were tested for their effect on wound healing. MTT assay showed that EGF increased NIH3T3 cell viability and confirmed that EGF used in this study was biologically active in vitro. Scanning electron microscope (SEM) showed that HA stably attached to scaffolds even after soaking in PBS for 48 h. ELISA assay showed that HA increased the adsorption of EGF to scaffolds and sustained the release of EGF from scaffolds. Animal study showed that the wounds covered with scaffolds containing HA and EGF recovered best among all 4 groups and had wound healing rates of 49.86%, 70.94% and 87.41% respectively for days 10, 15 and 20 post-surgery compared to scaffolds alone with wound healing rates of 29.26%, 42.80% and 70.14%. In addition, the wounds covered with scaffolds containing EGF alone were smaller than no EGF scaffolds on days 10, 15 and 20 post-surgery. Hematoxylin–Eosin (HE) staining confirmed these results by showing that on days 10, 15 and 20 post-surgery, the thicker epidermis and dermis layers were observed in the wounds covered with scaffolds containing HA and EGF than scaffolds alone. In addition, the thicker epidermis and dermis layers were also observed in the wounds covered with scaffolds containing EGF than scaffolds alone. Skin appendages were observed on day 20 only in the wound covered with scaffolds containing HA and EGF. These results demonstrate that the scaffolds containing HA and EGF can enhance wound healing. - Highlights: • HA can increase the adsorption of EGF to decellularized scaffolds. • HA can sustain the release of EGF from

  17. Appendage modal coordinate truncation criteria in hybrid coordinate dynamic analysis. [for spacecraft attitude control

    Science.gov (United States)

    Likins, P.; Ohkami, Y.; Wong, C.

    1976-01-01

    The paper examines the validity of the assumption that certain appendage-distributed (modal) coordinates can be truncated from a system model without unacceptable degradation of fidelity in hybrid coordinate dynamic analysis for attitude control of spacecraft with flexible appendages. Alternative truncation criteria are proposed and their interrelationships defined. Particular attention is given to truncation criteria based on eigenvalues, eigenvectors, and controllability and observability. No definitive resolution of the problem is advanced, and exhaustive study is required to obtain ultimate truncation criteria.

  18. Magnetic resonance imaging of epiploic appendagitis in children.

    Science.gov (United States)

    Boscarelli, Alessandro; Frediani, Simone; Ceccanti, Silvia; Falconi, Ilaria; Masselli, Gabriele; Casciani, Emanuele; Cozzi, Denis A

    2016-12-01

    In children, epiploic appendagitis has been seldom reported. We describe two children with clinical presentations mimicking appendicitis. A correct diagnosis was eventually achieved by magnetic resonance imaging (MRI) and confirmed at laparoscopy in the initial case. Our preliminary experience suggests that MRI is a valid and non-invasive alternative to computed tomography for characterization of unusual causes of pediatric abdominal pain in the acute hospital care setting. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Aneurysm of the Right Atrial Appendage

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    Silvio Henrique Barberato

    2002-02-01

    Full Text Available Atrial aneurysms involving the free wall or atrial appendage are rare entities in cardiology practice and may be associated with atrial arrhythmias or embolic phenomena. We review the literature and report a case of aneurysm of the right atrial appendage in a young adult, whose diagnosis was established with echocardiography after an episode of paroxysmal atrial flutter.

  20. Appendage mountable electronic devices conformable to surfaces

    Science.gov (United States)

    Rogers, John; Ying, Ming; Bonifas, Andrew; Lu, Nanshu

    2017-01-24

    Disclosed are appendage mountable electronic systems and related methods for covering and conforming to an appendage surface. A flexible or stretchable substrate has an inner surface for receiving an appendage, including an appendage having a curved surface, and an opposed outer surface that is accessible to external surfaces. A stretchable or flexible electronic device is supported by the substrate inner and/or outer surface, depending on the application of interest. The electronic device in combination with the substrate provides a net bending stiffness to facilitate conformal contact between the inner surface and a surface of the appendage provided within the enclosure. In an aspect, the system is capable of surface flipping without adversely impacting electronic device functionality, such as electronic devices comprising arrays of sensors, actuators, or both sensors and actuators.

  1. Appendage mountable electronic devices conformable to surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, John; Ying, Ming; Bonifas, Andrew; Lu, Nanshu

    2017-01-24

    Disclosed are appendage mountable electronic systems and related methods for covering and conforming to an appendage surface. A flexible or stretchable substrate has an inner surface for receiving an appendage, including an appendage having a curved surface, and an opposed outer surface that is accessible to external surfaces. A stretchable or flexible electronic device is supported by the substrate inner and/or outer surface, depending on the application of interest. The electronic device in combination with the substrate provides a net bending stiffness to facilitate conformal contact between the inner surface and a surface of the appendage provided within the enclosure. In an aspect, the system is capable of surface flipping without adversely impacting electronic device functionality, such as electronic devices comprising arrays of sensors, actuators, or both sensors and actuators.

  2. Caecal epiploic appendagitis: an unlikely occurrence

    Energy Technology Data Exchange (ETDEWEB)

    Macari, M. [Department of Radiology, Abdominal Imaging, NYU School of Medicine, NY (United States)], E-mail: michael.macari@nyumc.org; Laks, S.; Hajdu, C.; Babb, J. [Department of Radiology, Abdominal Imaging, NYU School of Medicine, NY (United States)

    2008-08-15

    Aim: To determine whether epiploic appendagitis occurs in the caecum. Methods: From 2000-2006, 58 cases with classic computed tomography (CT) features of acute epiploic appendagitis (focal round or oval fat density immediately adjacent to the colon with surrounding oedema and stranding, with or without a central area of high attenuation) were identified from a radiology information system and available for review on the picture archiving and communication system (PACS). Cases were assigned to one of six colonic segments: rectum, sigmoid, descending colon, transverse colon, ascending colon, and caecum. The Blyth-Still-Casella procedure was used to derive an exact upper bound on the likelihood of epiploic appendagitis occurring within the caecum. Results: Twenty-eight cases occurred in the sigmoid colon, 16 in the descending colon, four in the transverse colon, and 10 in the ascending colon. No cases of acute epiploic appendagitis were identified in the caecum. Four cases of prospectively dictated caecal epiploic appendagitis were identified from the database. Retrospective review of these cases showed two cases to be epiploic appendagitis of the ascending colon. The third case demonstrated peritoneal thickening without evidence of an inflamed epiploic appendage. The fourth case was caecal diverticulitis. Based on these findings there is 95% confidence that no more than 4.6% of patients with epiploic appendagitis will show this condition within the caecum. Conclusion: In the authors' experience, epiploic appendagitis does not occur in the caecum. Therefore, it is an unlikely cause for an inflammatory process in this region and other conditions should be considered.

  3. Appendagitis following Diagnostic Laparoscopy and Laparoscopic Appendicectomy

    Directory of Open Access Journals (Sweden)

    R. Kumar

    2016-01-01

    Full Text Available Appendagitis is an uncommon clinical entity, often not recognised, and mistaken for more serious infective conditions. We describe a proven case of appendagitis which occurred after confirmed appendicitis. We postulate that this condition can coexist with appendicitis and indeed may be the result of coinflammation. This has several implications. Firstly, clinicians must retain an index of suspicion for this condition in a patient with localised abdominal pain which occurs after appendicitis. Secondly, it would be reasonable to suggest careful examination of colocated appendages in a patient with an otherwise normal-appearing appendix. Treatment might require laparoscopic resection, as performed in this case.

  4. Platelet-rich plasma gel composited with nondegradable porous polyurethane scaffolds as a potential auricular cartilage alternative.

    Science.gov (United States)

    Wang, Zhongshan; Qin, Haiyan; Feng, Zhihong; Zhao, Yimin

    2016-02-01

    Total auricular reconstruction is still a challenge, and autologous cartilage transplant is the main therapy so far. Tissue engineering provides a promising method for auricular cartilage reconstruction. However, although degradable framework demonstrated excellent initial cosmetic details, it is difficult to maintain the auricular contour over time and the metabolites tended to be harmful to human body. In this study, biocompatible and safe nondegradable elastic polyurethane was used to make porous scaffold in specific details by rapid prototyping technology. Platelet-rich plasma contains fibrin and abundant autologous growth factors, which was used as cell carriers for in vitro expanded cells. When crosslinking polyurethane framework, platelet-rich plasma and cells together, we successfully made polyurethane/platelet-rich plasma/cell composites, and implanted them into dorsal subcutaneous space of nude mice. The results showed that this method resulted in more even cell distribution and higher cell density, promoted chondrocyte proliferation, induced higher level expressions of aggrecan and type II collagen gene, increased content of newly developed glycosaminoglycans, and produced high-quality cartilaginous tissue. This kind of cartilage tissue engineering approach may be a potential promising alternative for external ear reconstruction.

  5. Left Atrial Appendage Occlusion for Stroke Prevention.

    Science.gov (United States)

    Chanda, Arijit; Reilly, John P

    More than 2.3 million adults in the United States have atrial fibrillation (AF), which exposes them to a 5-fold increased risk of stroke. The left atrial appendage (LAA) appears to be the source of thrombus formation in the vast majority of these patients. Anticoagulation significantly reduces the risk of stroke, but often we encounter patients who have absolute or relative contraindication to anticoagulation. Percutaneous LAA exclusion offers an alternative to anticoagulation to decrease the risk of stroke. Three device systems are currently available in the United States. The WATCHMAN® device is the most studied and approved by Food and Drug Administration (FDA) to be used in patients with AF unsuitable for anticoagulation who are at a high risk of stroke. The Amulet® device is currently being used as part of the AMPLATZER® Amulet® LAA Occluder trial, which is a non-inferiority randomized trial comparing the Amulet® to the WATCHMAN® device. The third device in use is the LARIAT®, which is an FDA approved snare and pre-tied stich system. It is used to approximate soft tissue which in this case is the LAA. It is a hybrid system and requires both epicardial and endocardial access. The main obstacle to percutaneous LAA closure is procedural related complications, which can be minimized with optimum operator experience. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Congenital left atrial appendage aneurysm: Atypical presentation

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    Mehdi Bamous

    2017-01-01

    Full Text Available Congenital left atrial appendage aneurysm is a rare condition caused by dysplasia of the atrial muscles. We report a case of a 14-year-old boy, with a 5-month history of cough and in sinus rhythm. Transthoracic echocardiography and computerized tomographic angiography confirmed the aneurysm of the left atrial appendage which was resected through median sternotomy on cardiopulmonary bypass. This case is presented not only for its rarity but also for its atypical clinical presentation.

  7. Scaffolded biology.

    Science.gov (United States)

    Minelli, Alessandro

    2016-09-01

    Descriptions and interpretations of the natural world are dominated by dichotomies such as organism vs. environment, nature vs. nurture, genetic vs. epigenetic, but in the last couple of decades strong dissatisfaction with those partitions has been repeatedly voiced and a number of alternative perspectives have been suggested, from perspectives such as Dawkins' extended phenotype, Turner's extended organism, Oyama's Developmental Systems Theory and Odling-Smee's niche construction theory. Last in time is the description of biological phenomena in terms of hybrids between an organism (scaffolded system) and a living or non-living scaffold, forming unit systems to study processes such as reproduction and development. As scaffold, eventually, we can define any resource used by the biological system, especially in development and reproduction, without incorporating it as happens in the case of resources fueling metabolism. Addressing biological systems as functionally scaffolded systems may help pointing to functional relationships that can impart temporal marking to the developmental process and thus explain its irreversibility; revisiting the boundary between development and metabolism and also regeneration phenomena, by suggesting a conceptual framework within which to investigate phenomena of regular hypermorphic regeneration such as characteristic of deer antlers; fixing a periodization of development in terms of the times at which a scaffolding relationship begins or is terminated; and promoting plant galls to legitimate study objects of developmental biology.

  8. Use of the Nanofitin Alternative Scaffold as a GFP-Ready Fusion Tag.

    Directory of Open Access Journals (Sweden)

    Simon Huet

    Full Text Available With the continuous diversification of recombinant DNA technologies, the possibilities for new tailor-made protein engineering have extended on an on-going basis. Among these strategies, the use of the green fluorescent protein (GFP as a fusion domain has been widely adopted for cellular imaging and protein localization. Following the lead of the direct head-to-tail fusion of GFP, we proposed to provide additional features to recombinant proteins by genetic fusion of artificially derived binders. Thus, we reported a GFP-ready fusion tag consisting of a small and robust fusion-friendly anti-GFP Nanofitin binding domain as a proof-of-concept. While limiting steric effects on the carrier, the GFP-ready tag allows the capture of GFP or its blue (BFP, cyan (CFP and yellow (YFP alternatives. Here, we described the generation of the GFP-ready tag from the selection of a Nanofitin variant binding to the GFP and its spectral variants with a nanomolar affinity, while displaying a remarkable folding stability, as demonstrated by its full resistance upon thermal sterilization process or the full chemical synthesis of Nanofitins. To illustrate the potential of the Nanofitin-based tag as a fusion partner, we compared the expression level in Escherichia coli and activity profile of recombinant human tumor necrosis factor alpha (TNFα constructs, fused to a SUMO or GFP-ready tag. Very similar expression levels were found with the two fusion technologies. Both domains of the GFP-ready tagged TNFα were proved fully active in ELISA and interferometry binding assays, allowing the simultaneous capture by an anti-TNFα antibody and binding to the GFP, and its spectral mutants. The GFP-ready tag was also shown inert in a L929 cell based assay, demonstrating the potent TNFα mediated apoptosis induction by the GFP-ready tagged TNFα. Eventually, we proposed the GFP-ready tag as a versatile capture and labeling system in addition to expected applications of anti

  9. Biphasic calcium phosphate nano-composite scaffolds reinforced with bioglass provide a synthetic alternative to autografts in a canine tibiofibula defect model

    Institute of Scientific and Technical Information of China (English)

    Tang Dezhi; Xu Guohua; Yang Zhou; Holz Jonathan; Ye Xiaojian; Cai Shu; Yuan Wen

    2014-01-01

    Background Bone grafting is commonly used to repair bone defects.As the porosity of the graft scaffold increases,bone formation increases,but the strength decreases.Early attempts to engineer materials were not able to resolve this problem.In recent years,nanomaterials have demonstrated the unique ability to improve the material strength and toughness while stimulating new bone formation.In our previous studies,we synthesized a nano-scale material by reinforcing a porous β-tricalcium phosphate (β-TCP) ceramic scaffold with Na2O-MgO-P2O5-CaO bioglass (β-TCP/BG).However,the in vivo effects of the β-TCP/BG scaffold on bone repair remain unknown.Methods We investigated the efficacy of β-TCP/BG scaffolds compared to autografts in a canine tibioflbula defect model.The tibioflbula defects were created in the right legs of 12 dogs,which were randomly assigned to either the scaffold group or the autograft group (six dogs per group).Radiographic evaluation was performed at 0,4,8,and 12 weeks post-surgery.The involved tibias were extracted at 12 weeks and were tested to failure via a three-point bending.After the biomechanical analysis,specimens were subsequently processed for scanning electron microscopy analysis and histological evaluations.Results Radiographic evaluation at 12 weeks post-operation revealed many newly formed osseous calluses and bony unions in both groups.Both the maximum force and break force in the scaffold group (n=6) were comparable to those in the autograft group (n=6,P >0.05),suggesting that the tissue-engineered bone repair achieved similar biomechanical properties to autograft bone repair.At 12 weeks post-operation,obvious new bone and blood vessel formations were observed in the artificial bone of the experimental group.Conclusions The results demonstrated that new bone formation and high bone strength were achieved in the β-TCP/ BG scaffold group,and suggested that the β-TCP/BG scaffold could be used as a synthetic alternative to

  10. Hemostasis of Left Atrial Appendage Bleed With Lariat Device

    Directory of Open Access Journals (Sweden)

    Amena Hussain, MD

    2014-09-01

    Full Text Available New devices designed for minimally invasive closure of the left atrial appendage (LAA may be a viable alternative for patients in whom anticoagulation is considered high risk. The Lariat (Sentreheart, Redwood City, CA, which is currently FDA-approved for percutaneous closure of tissue, requires both trans-septal puncture and epicardial access. However it requires no anticoagulation after the procedure. Here we describe a case of effusion and tamponade during a Lariat procedure with successful completion of the case and resolution of the effusion.

  11. Scaffolds in Tendon Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Umile Giuseppe Longo

    2012-01-01

    Full Text Available Tissue engineering techniques using novel scaffold materials offer potential alternatives for managing tendon disorders. Tissue engineering strategies to improve tendon repair healing include the use of scaffolds, growth factors, cell seeding, or a combination of these approaches. Scaffolds have been the most common strategy investigated to date. Available scaffolds for tendon repair include both biological scaffolds, obtained from mammalian tissues, and synthetic scaffolds, manufactured from chemical compounds. Preliminary studies support the idea that scaffolds can provide an alternative for tendon augmentation with an enormous therapeutic potential. However, available data are lacking to allow definitive conclusion on the use of scaffolds for tendon augmentation. We review the current basic science and clinical understanding in the field of scaffolds and tissue engineering for tendon repair.

  12. Recurrent epiploic appendagitis mimicking appendicitis and cholecystitis

    Science.gov (United States)

    Hearne, Christopher B.; Taboada, Jorge

    2017-01-01

    Epiploic appendagitis (EA) is a rare cause of acute abdominal pain caused by inflammation of an epiploic appendage. It has a nonspecific clinical presentation that may mimic other acute abdominal pathologies on physical exam, such as appendicitis, diverticulitis, or cholecystitis. However, EA is usually benign and self-limiting and can be treated conservatively. We present the case of a patient with two episodes of EA, the first mimicking acute appendicitis and the second mimicking acute cholecystitis. Although recurrence of EA is rare, it should be part of the differential diagnosis of acute, localized abdominal pain. A correct diagnosis of EA will prevent unnecessary hospitalization, antibiotic use, and surgical procedures. PMID:28127129

  13. Right juxtaposition of the atrial appendages.

    Science.gov (United States)

    Mathew, R; Replogle, R; Thilenius, O G; Arcilla, R A

    1975-04-01

    We present an infant with right-sided juxtaposition of atrial appendages who had open heart surgery for ventricular septal defect and patent ductus arteriosus. Of 12 cases thus far reported, ventricular d-loop was observed in nine, and normal position of great vessels in four. Contrary to previous views, this condition may not be accompanied by severe conotruncal anomalies.

  14. Percutaneous left atrial appendage closure for stroke prevention

    DEFF Research Database (Denmark)

    De Backer, Ole; Loupis, Anastasia M; Ihlemann, Nikolaj

    2014-01-01

    INTRODUCTION: In atrial fibrillation (AF) patients with an increased stroke risk, oral anticoagulation (OAC) is the standard treatment for stroke prevention. However, this therapy carries a high risk of major bleeding. Percutaneous closure of the left atrial appendage (LAA) is suggested as an alt......INTRODUCTION: In atrial fibrillation (AF) patients with an increased stroke risk, oral anticoagulation (OAC) is the standard treatment for stroke prevention. However, this therapy carries a high risk of major bleeding. Percutaneous closure of the left atrial appendage (LAA) is suggested...... as an alternative option for stroke prevention in AF patients with contraindication(s) for OAC treatment. MATERIAL AND METHODS: A total of 42 patients underwent percutaneous LAA closure. In this report, we describe our experience with this procedure. RESULTS: The patients treated were AF patients with a high stroke...... risk (CHADS-VASc 4.5±1.4) and contra-indication(s) for OAC and/or a high bleeding risk (HAS-BLED 3.7±0.9). A history of intracerebral bleeding was the most common reason for LAA closure. Successful implantation was obtained in 41 of 42 patients. One major peri-procedural complication occurred; a major...

  15. CT features of primary epiploic appendagitis

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Keng Sin [Department of Oncologic Imaging, National Cancer Centre, 11 Hospital Drive, Singapore 169610 (Singapore)]. E-mail: ngkeng@gmail.com; Tan, Andrew Gee Seng [Department of Radiology, Changi General Hospital, 2 Simei Street 3, Singapore 529889, Singapore. (Singapore); Chen, Kevin K' o Wen [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Wong, Siew Kune [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore); Tan, How Ming [Department of Diagnostic Radiology, Singapore General Hospital, Outram Road, Singapore 169608 (Singapore)

    2006-08-15

    Objective: The aim of this study is to describe the computed tomography (CT) findings of primary epiploic appendagitis (PEA). Methods: We reviewed the clinical records and CT images of 14 consecutive patients in Singapore who presented with acute abdominal pain from July 2000 to April 2004 and had radiological signs of PEA. Results: Hyperattenuated ring with adjacent fat stranding was present in all the patients. The central high attenuation dot was seen in 42.9% (6/14) of the patients. We observed a lobulated fatty mass in 21.4% (3/14) of our patients. All patients recovered during clinical follow-up. Conclusions: We believe the lobulated appearance of PEA is due to two or more, contiguous infarcted epiploic appendages lying in close proximity. This appearance further aids in the diagnosis of PEA and helps differentiates the condition from omental infarction. Recognizing the CT signs of PEA should allow a confident diagnosis and avoid unnecessary surgery.

  16. Primary epiploic appendagitis: from A to Z

    Directory of Open Access Journals (Sweden)

    Iyad A Issa

    2010-07-01

    Full Text Available Iyad A Issa1, Mohamad-Tarek Berjaoui2, Wajdi S Hamdan21Department of Gastroenterology and Hepatology, Rafik Hariri University Hospital, Beirut, Lebanon; 2Department of General Surgery, Rafik Hariri University Hospital, Beirut, LebanonAbstract: Epiploic appendagitis is a rare and uncommon diagnosis that is frequently unknown to clinicians. Inflammation is usually acute and causes abrupt symptoms, but once the diagnosis is accurately made, most patients respond to pain control and conservative management. We report the case of a young woman presenting with acute primary epiploic appendagitis of the right colon. The inflammatory mass was unusually large and occurred a few months after surgery for gastric bypass. This case will give us the opportunity to discuss the clinical presentation of this disease, as well as the potential associations and risk factors and the means for adequate diagnosis and treatment.Keywords: appendices, epiploicae, bypass surgery, inflammation, computed tomography

  17. Primary epiploic appendagitis: US and CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Molla, E.; Ripolles, T.; Martinez, M.J.; Morote, V. [Department of Radiology, Hospital Dr. Peset, Valencia (Spain); Rosello-Sastre, E. [Department of Pathology, Hospital Dr. Peset, Valencia (Spain)

    1998-03-27

    A retrospective review is presented of seven cases of epiploic appendagitis, with surgical confirmation in one case. The main clinico-analytical data and the US and CT findings are described, as well as the histopathologic features in the sole case that underwent surgical resection. We also calculated the frequency of this entity in patients undergoing emergency abdominal US on clinical suspicion of diverticulitis. In all seven cases the clinico-analytical evidence was nonspecific (localized acute abdominal pain and slight leukocytosis), mimicking in six cases the clinical presentation of sigmoid diverticulitis and in one case that of acute appendicitis. US imaging findings were characteristic: a hyperechoic mass localized under the point of maximum pain, adjacent to the anterior peritoneal wall and fixed during deep breathing. In none of the cases did color Doppler US show flow. CT findings were also typical and showed a mass with a peripheral hyperattenuated rim surrounding an area of fatty attenuation. Overall 7.1 % of patients investigated to exclude sigmoid diverticulitis finally showed findings of primary epiploic appendagitis. Primary epiploic appendagitis thus shows characteristic US and CT findings that allow its diagnosis and follow-up. This entity is much more frequent than previously reported, especially in patients referred for US to exclude sigmoid diverticulitis. (orig.) With 4 figs., 14 refs.

  18. Role of Imaging in Left Atrial Appendage Occlusion

    Directory of Open Access Journals (Sweden)

    Mathieu Lempereur

    2017-04-01

    Full Text Available Percutaneous left atrial appendage (LAA occlusion is now a valid alternative to long-term oral anticoagulation in patients with non-valvular atrial fibrillation at high thrombo-embolism risk, especially for patients who are considered ineligible for anticoagulation. The most frequently used occluders worldwide include the WATCHAMN (Boston Scientific, Natick, MA, USA and the Amplatzer Cardiac Plug or Amulet (St. Jude Medical/Abbott, St Paul, MN, USA devices. Multimodality imaging is key in the understanding of 3D aspects of the LAA and surrounding structures anatomy. Imaging is essential for procedural planning, during each step of the procedure and for device surveillance after implantation. Multimodality imaging, including 2D/3D echocardiography, fluoroscopy, and cardiac computed tomography can increase the safety and efficacy of the procedure.

  19. Development of laser welded appendages to Zircaloy-4 fuel tubing (sheath/cladding)

    Energy Technology Data Exchange (ETDEWEB)

    Livingstone, S., E-mail: steve.livingstone@cnl.ca [Canadian Nuclear Laboratories Limited, Chalk River, ON, Canada K0J 1J0 (Canada); Xiao, L. [Canadian Nuclear Laboratories Limited, Chalk River, ON, Canada K0J 1J0 (Canada); Corcoran, E.C.; Ferrier, G.A.; Potter, K.N. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, Canada K7K 7B4 (Canada)

    2015-04-01

    Highlights: • Examines feasibility of laser welding appendages to Zr-4 tubing. • Laser welding minimizes the HAZ and removes toxic Be. • Mechanical properties of laser welds appear competitive with induction brazed joints. • Work appears promising and lays the foundation for further investigations. - Abstract: Laser welding is a potential alternative to the induction brazing process commonly used for appendage attachment in CANDU{sup ®} fuel fabrication that uses toxic Be as a filler metal, and creates multiple large heat affected zones in the sheath. For this work, several appendages were laser welded to tubing using different laser heat input settings and then examined with a variety of techniques: visual examination, metallography, shear strength testing, impact testing, and fracture surface analysis. Where possible, the examination results are contrasted against production induction brazed joints. The work to date looks promising for laser welded appendages. Further work on joint optimization, corrosion testing, irradiation testing, and post-irradiation examination will be performed in the future.

  20. Juxtaposed atrial appendages: A curiosity with some clinical relevance

    Directory of Open Access Journals (Sweden)

    Anil Kumar Singhi

    2016-01-01

    Full Text Available If the atrial appendages lie adjacent to each other on same side of the great arteries, instead of encircling their roots, they are referred as juxtaposed. Right juxtaposition of atrial appendages is less common than left juxtaposition. The images demonstrate the classical radiological, echocardiographic, and surgical images of juxtaposed atrial appendages. Their clinical incidence, associations, and relevance during interventional and surgical procedures are discussed.

  1. Study on the incidence of testicular and epididymal appendages in patients with cryptorchidism

    Directory of Open Access Journals (Sweden)

    Favorito Luciano A.

    2004-01-01

    Full Text Available OBJECTIVE: To study the incidence of testicular and epididymal appendages in patients with cryptorchidism. MATERIALS AND METHODS: We studied 65 patients with cryptorchidism, totalizing 83 testes and 40 patients who had prostate adenocarcinoma and hydrocele (control group, totalizing 55 testes. The following situations were analyzed: I absence of testicular and epididymal appendages, II presence of testicular appendage only, III presence of epididymal appendage, IV presence of testicular and epididymal appendage, V presence of 2 epididymal appendages and 1 testicular appendage and VI presence of paradidymis or vas aberrans of Haller. RESULTS: In patients with cryptorchidism we found testicular appendages in 23 cases (41.8%, epididymal appendages in 9 (16.3%, testicular and epididymal appendage in 8 (14.5%, 2 epididymal appendages and 1 testicular in 1 (1.8% and absence of appendages in 14 (25.4%. In the control group, we found testicular appendages in 29 (34.9%, epididymal appendages in 19 (22.8%, testicular and epididymal appendage in 7 (8.4%, and absence of appendages in 28 (33.7%, we did not find 2 epididymal appendages in this group, and none of the patients in the 2 groups presented paradidymis or vas aberrans of Haller. CONCLUSION: The occurrence of testicular and epididymal appendages is quite variable. There was no statistically significant difference in the incidence and distribution of the testicular and epididymal appendages between patients with cryptorchidism and those from the control group.

  2. Left atrial appendage occlusion with the Amplatzer Amulet for stroke prevention in atrial fibrillation: the first case in Greece.

    Science.gov (United States)

    Tzikas, Apostolos; Karagounis, Lambros; Bouktsi, Maria; Drevelegas, Antonios; Parcharidou, Despina; Ioannidis, Stathis; Krasopoulos, George; Giannakoulas, George

    2013-01-01

    Left atrial appendage (LAA) occlusion has been introduced into clinical practice as a valuable alternative to oral anticoagulation for stroke prevention in patients with non-valvular atrial fibrillation. In this case presentation we describe the first LAA occlusion in Greece using the Amplatzer Amulet device. We also briefly discuss issues related to procedural safety and multimodality imaging for LAA occlusion.

  3. Percutaneous left atrial appendage closure: Technical aspects and prevention of periprocedural complications with the watchman device

    Institute of Scientific and Technical Information of China (English)

    Sven; M?bius-Winkler; Nicolas; Majunke; Marcus; Sandri; Norman; Mangner; Axel; Linke; Gregg; W; Stone; Ingo; D?hnert; Gerhard; Schuler; Peter; B; Sick

    2015-01-01

    Transcatheter closure of the left atrial appendage has been developed as an alternative to chronic oral anticoagulation for stroke prevention in patients with atrial fibrillation, and as a primary therapy for patients with contraindications to chronic oral anticoagulation. The promise of this new intervention compared with warfarin has been supported by several, small studies and two pivotal randomized trial with the Watchman Device. The results regarding risk reduction for stroke have been favourable although acute complications were not infrequent. Procedural complications, which are mainly related to transseptal puncture and device implantation, include air embolism, pericardial effusions/tamponade and device embolization. Knowledge of nature, management and prevention of complications should minimize the risk of complications and allow transcatheter left atrial appendage closure to emerge as a therapeutic option for patients with atrial fibrillation at risk for cardioembolic stroke.

  4. Mosaic trisomy 13 and a sacral appendage.

    Science.gov (United States)

    Pachajoa, Harry; Meza Escobar, Luis Enrique

    2013-07-31

    Mosaic trisomy 13 occurs when there is a percentage of trisomic cells for an entire chromosome 13, while the remaining percentage of cells is euploid. The prevalence of this syndrome ranges from 1 in 10 000 to 1 in 20 000 births. Complete, partial or mosaic forms of this disorder can occur. The phenotype of mosaic trisomy 13 patients varies widely. Patients with mosaic trisomy 13 usually have a longer survival and a less severe phenotype compared to patients with complete trisomy 13. Genetic counselling is difficult due to the wide variation among the clinical manifestations of these patients. There have been 49 cases of mosaic trisomy 13 reported in the literature. We report the case of a patient with mosaic trisomy 13, a sacral appendage and a cleft lip and palate.

  5. Partial co-option of the appendage patterning pathway in the development of abdominal appendages in the sepsid fly Themira biloba.

    Science.gov (United States)

    Bowsher, Julia H; Nijhout, H Frederik

    2009-12-01

    The abdominal appendages on male Themira biloba (Diptera: Sepsidae) are complex novel structures used during mating. These abdominal appendages superficially resemble the serially homologous insect appendages in that they have a joint and a short segment that can be rotated. Non-genital appendages do not occur in adult pterygote insects, so these abdominal appendages are novel structures with no obvious ancestry. We investigated whether the genes that pattern the serially homologous insect appendages have been co-opted to pattern these novel abdominal appendages. Immunohistochemistry was used to determine the expression patterns of the genes extradenticle (exd), Distal-less (Dll), engrailed (en), Notch, and the Bithorax Complex in the appendages of T. biloba during pupation. The expression patterns of Exd, En, and Notch were consistent with the hypothesis that a portion of the patterning pathway that establishes the coxopodite has been co-opted to pattern the developing abdominal appendages. However, Dll was only expressed in the bristles of the developing appendages and not the proximal-distal axis of the appendage itself. The lack of Dll expression indicates the absence of a distal domain of the appendage suggesting that sepsid abdominal appendages only use genes that normally pattern the base of segmental appendages.

  6. A Rare Cause of Abdominal Pain: Primary Epiploic Appendagitis (PEA

    Directory of Open Access Journals (Sweden)

    Gulbanu Erkan

    2016-07-01

    Full Text Available Primary epiploic appendagitis (PEA is a rare disease caused by torsion or spontaneous thrombosis of the central vein that drains epiploic appendages (EA. Primary Epiploic Appendagitis (PEA is an ischemic infarction. Although PEA is a self-limiting disease and does not require surgical intervention in most cases, it may mimic diseases that require surgical intervention or aggressive medical therapy, such as appendicitis, diverticulitis, or cholecystitis. In order to avoid unnecessary surgical intervention, PEA should be kept in mind when patients present with acute abdominal pain. In this report, we present a PEA case admitted with abdominal pain.

  7. Trichohyalin-like proteins have evolutionarily conserved roles in the morphogenesis of skin appendages.

    Science.gov (United States)

    Mlitz, Veronika; Strasser, Bettina; Jaeger, Karin; Hermann, Marcela; Ghannadan, Minoo; Buchberger, Maria; Alibardi, Lorenzo; Tschachler, Erwin; Eckhart, Leopold

    2014-11-01

    S100 fused-type proteins (SFTPs) such as filaggrin, trichohyalin, and cornulin are differentially expressed in cornifying keratinocytes of the epidermis and various skin appendages. To determine evolutionarily conserved, and thus presumably important, features of SFTPs, we characterized nonmammalian SFTPs and compared their amino acid sequences and expression patterns with those of mammalian SFTPs. We identified an ortholog of cornulin and a previously unknown SFTP, termed scaffoldin, in reptiles and birds, whereas filaggrin was confined to mammals. In contrast to mammalian SFTPs, both cornulin and scaffoldin of the chicken are expressed in the embryonic periderm. However, scaffoldin resembles mammalian trichohyalin with regard to its expression in the filiform papillae of the tongue and in the epithelium underneath the forming tips of the claws. Furthermore, scaffoldin is expressed in the epithelial sheath around growing feathers, reminiscent of trichohyalin expression in the inner root sheath of hair. The results of this study show that SFTP-positive epithelia function as scaffolds for the growth of diverse skin appendages such as claws, nails, hair, and feathers, indicating a common evolutionary origin.

  8. The comparative hydrodynamics of rapid rotation by predatory appendages.

    Science.gov (United States)

    McHenry, M J; Anderson, P S L; Van Wassenbergh, S; Matthews, D G; Summers, A P; Patek, S N

    2016-11-01

    Countless aquatic animals rotate appendages through the water, yet fluid forces are typically modeled with translational motion. To elucidate the hydrodynamics of rotation, we analyzed the raptorial appendages of mantis shrimp (Stomatopoda) using a combination of flume experiments, mathematical modeling and phylogenetic comparative analyses. We found that computationally efficient blade-element models offered an accurate first-order approximation of drag, when compared with a more elaborate computational fluid-dynamic model. Taking advantage of this efficiency, we compared the hydrodynamics of the raptorial appendage in different species, including a newly measured spearing species, Coronis scolopendra The ultrafast appendages of a smasher species (Odontodactylus scyllarus) were an order of magnitude smaller, yet experienced values of drag-induced torque similar to those of a spearing species (Lysiosquillina maculata). The dactyl, a stabbing segment that can be opened at the distal end of the appendage, generated substantial additional drag in the smasher, but not in the spearer, which uses the segment to capture evasive prey. Phylogenetic comparative analyses revealed that larger mantis shrimp species strike more slowly, regardless of whether they smash or spear their prey. In summary, drag was minimally affected by shape, whereas size, speed and dactyl orientation dominated and differentiated the hydrodynamic forces across species and sizes. This study demonstrates the utility of simple mathematical modeling for comparative analyses and illustrates the multi-faceted consequences of drag during the evolutionary diversification of rotating appendages. © 2016. Published by The Company of Biologists Ltd.

  9. Semiotic scaffolding

    DEFF Research Database (Denmark)

    Hoffmeyer, Jesper

    2015-01-01

    Life processes at all levels (from the genetic to the behavioral) are coordinated by semiotic interactions between cells, tissues, membranes, organs, or individuals and tuned through evolution to stabilize important functions. A stabilizing dynamics based on a system of semiotic scaffoldings...... implies that genes do not control the life of organisms, they merely scaffold it. The nature-nurture dynamics is thus far more complex and open than is often claimed. Contrary to physically based interactions, semiotic interactions do not depend on any direct causal connection between the sign vehicle...... semiotic scaffolding is not, of course, exclusive for phylogenetic and ontogenetic development, it is also an important dynamical element in cultural evolution....

  10. Computational Exploration of Molecular Scaffolds in Medicinal Chemistry.

    Science.gov (United States)

    Hu, Ye; Stumpfe, Dagmar; Bajorath, Jürgen

    2016-05-12

    The scaffold concept is widely applied in medicinal chemistry. Scaffolds are mostly used to represent core structures of bioactive compounds. Although the scaffold concept has limitations and is often viewed differently from a chemical and computational perspective, it has provided a basis for systematic investigations of molecular cores and building blocks, going far beyond the consideration of individual compound series. Over the past 2 decades, alternative scaffold definitions and organization schemes have been introduced and scaffolds have been studied in a variety of ways and increasingly on a large scale. Major applications of the scaffold concept include the generation of molecular hierarchies, structural classification, association of scaffolds with biological activities, and activity prediction. This contribution discusses computational approaches for scaffold generation and analysis, with emphasis on recent developments impacting medicinal chemistry. A variety of scaffold-based studies are discussed, and a perspective on scaffold methods is provided.

  11. Occlusion of left atrial appendage in patients with atrial fibrillation

    Directory of Open Access Journals (Sweden)

    О. Н. Ганеева

    2015-10-01

    Full Text Available The article reviews a new method of prophylaxis of thromboembolitic complications, specifically occlusion of left atrial appendage, in patients with atrial fibrillation. Indications and contraindications for the procedure, as well as a step-by-step process of the intervention itself are described. Special emphasis is placed on the up-to-date evidence and the review of clinical trials.

  12. Selected Disorders of Skin Appendages--Acne, Alopecia, Hyperhidrosis.

    Science.gov (United States)

    Vary, Jay C

    2015-11-01

    This article reviewed some of the more common diseases of the skin appendages that are encountered in medicine: hyperhidrosis, acne, AA, FPHL, AGA, and TE. The pathophysiology behind the conditions and their treatments were discussed so that the clinician can make logical therapeutic choices for their affected patients.

  13. Left atrial appendage occlusion with the AMPLATZER Amulet device

    DEFF Research Database (Denmark)

    Tzikas, Apostolos; Gafoor, Sameer; Meerkin, David

    2016-01-01

    anatomies like "chicken wing" left atrial appendage. Finally, for operators who are switching from AMPLATZER Cardiac Plug to Amulet, the main differences between the two devices with respect to implantation technique are presented. CONCLUSIONS: In conclusion, this document reflects a consensus approach...

  14. Left atrial appendage occlusion for stroke prevention in atrial fibrillation

    DEFF Research Database (Denmark)

    Tzikas, Apostolos; Shakir, Samera; Gafoor, Sameer;

    2015-01-01

    Aims: To investigate the safety, feasibility, and efficacy of left atrial appendage occlusion (LAAO) with the AMPLATZER Cardiac Plug (ACP) for stroke prevention in patients with atrial fibrillation (AF). Methods and results: Data from consecutive patients treated in 22 centres were collected...

  15. Percutaneous vascular plug for incomplete surgical left atrial appendage closure.

    Science.gov (United States)

    Levisay, Justin P; Sangodkar, Sandeep; Salinger, Michael H; Lampert, Mark; Feldman, Ted

    2014-04-01

    Surgical left atrial appendage (LAA) exclusion has a failure rate as high as 60% due to persistent residual flow in the LAA or large LAA remnants. We describe a novel technique for treatment of incomplete surgical LAA ligation, and define the mechanism that led to persistence of the remnant LAA without any thrombus formation.

  16. Primary ciliogenesis requires the distal appendage component Cep123

    Directory of Open Access Journals (Sweden)

    James E. Sillibourne

    2013-04-01

    Primary cilium formation is initiated at the distal end of the mother centriole in a highly co-ordinated manner. This requires the capping of the distal end of the mother centriole with a ciliary vesicle and the anchoring of the basal body (mother centriole to the cell cortex, both of which are mediated by the distal appendages. Here, we show that the distal appendage protein Cep123 (Cep89/CCDC123 is required for the assembly, but not the maintenance, of a primary cilium. In the absence of Cep123 ciliary vesicle formation fails, suggesting that it functions in the early stages of primary ciliogenesis. Consistent with such a role, Cep123 interacts with the centriolar satellite proteins PCM-1, Cep290 and OFD1, all of which play a role in primary ciliogenesis. These interactions are mediated by a domain in the C-terminus of Cep123 (400–783 that overlaps the distal appendage-targeting domain (500–600. Together, the data implicate Cep123 as a new player in the primary ciliogenesis pathway and expand upon the role of the distal appendages in this process.

  17. Percutaneous left atrial appendage closure devices: safety, efficacy, and clinical utility

    Directory of Open Access Journals (Sweden)

    Swaans MJ

    2016-09-01

    Full Text Available Martin J Swaans, Lisette IS Wintgens, Arash Alipour,  Benno JWM Rensing, Lucas VA Boersma Department of Cardiology, St. Antonius Hospital, Nieuwegein, the Netherlands Abstract: Atrial fibrillation (AF is the most common arrhythmia treated in the clinical practice. One of the major complications of AF is a thromboembolic cerebral ischemic event. Up to 20% of all strokes are caused by AF. Thromboembolic cerebral ischemic event in patients with AF occurs due to atrial thrombi, mainly from the left atrial appendage (LAA. Prevention of clot formation with antiplatelet agents and especially oral anticoagulants (­vitamin K antagonists or newer oral anticoagulants has been shown to be effective in reducing the stroke risk in patients with AF but has several drawbacks with (major bleedings as the most important disadvantage. Therefore, physical elimination of the LAA, which excludes the site of clot formation by surgical or percutaneous techniques, might be a good alternative. In this review, we discuss the safety, efficacy, and clinical utility of the Watchman™ LAA closure device. Keywords: stroke, left atrial appendage, prevention, atrial fibrillation

  18. Left atrial appendage closure: patient, device and post-procedure drug selection.

    Science.gov (United States)

    Tzikas, Apostolos; Bergmann, Martin W

    2016-05-17

    Left atrial appendage closure (LAAC), a device-based therapy for stroke prevention in patients with atrial fibrillation, is considered an alternative to oral anticoagulation therapy, particularly for patients at high risk of bleeding. Proof of concept has been demonstrated by the PROTECT AF and PREVAIL trials which evaluated the WATCHMAN device (Boston Scientific, Marlborough, MA, USA) versus warfarin, showing favourable outcome for the device group. The most commonly used devices for LAAC are the WATCHMAN and its successor, the WATCHMAN FLX (Boston Scientific) and the AMPLATZER Cardiac Plug and more recently the AMPLATZER Amulet device (both St. Jude Medical, St. Paul, MN, USA). The procedure is typically performed via a transseptal puncture under fluoroscopic and echocardiographic guidance. Technically, it is considered quite demanding due to the anatomic variability and fragility of the appendage. Careful material manipulation, adequate operator training, and good cardiac imaging and device sizing allow a safe, uneventful procedure. Post-procedure antithrombotic drug selection is based on the patient's history, indication and quality of LAAC.

  19. Overlay Technique for Transcatheter Left Atrial Appendage Closure.

    Science.gov (United States)

    Li, Shuang; Zhu, Mengyun; Lu, Yunlan; Tang, Kai; Zhao, Dongdong; Chen, Wei; Xu, Yawei

    2015-08-01

    The Overlay technique is popular in peripheral artery interventions, but not in coronary or cardiac structural procedures. We present an initial experience using three-episode overlays during a transcatheter left atrial appendage closure. The first overlay was applied to facilitate advancement of the delivery sheath into left atrium. The second overlay was used to navigate the advancement of prepped delivery system containing the compressed occluder into its optimal position in the left atrium. The third overlay facilitated the real-time deployment of the closure device. This case report demonstrates the effectiveness of the overlay technique in facilitating each step of the transcatheter left atrial appendage closure. Copyright © 2015 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  20. A Rare Cause of Acute Abdominal Pain: Primary Appendagitis Epiploica

    Directory of Open Access Journals (Sweden)

    Tarkan Ergun

    2014-03-01

    Primary appendagitis epiploica – one of the causes of acute abdominal pain – is a self-limited rare benign inflammatory condition involving the colonic epiploic appendages. Their therapy is conservative and clinically mimics other conditions requiring surgery such as acute diverticulitis or appendicitis. However, being a quite rare condition is the reason they are usually neglected by both the surgeon and the radiologist. However the computed tomography (CT findings are rather characteristic and pathognomonic. Thus, to consider CT as the diagnostic modality of choice is extremely important in order to diagnose the condition and to avoid unnecessary surgical interventions.             This is a paper reporting an acute abdominal pain case of primary appendicitis epiploica diagnosed using computed tomography. 

  1. Developmental Scaffolding

    DEFF Research Database (Denmark)

    Giorgi, Franco; Bruni, Luis Emilio

    2015-01-01

    . Within the developmental hierarchy, each module yields an inter-level relationship that makes it possible for the scaffolding to mediate the production of selectable variations. Awide range of genetic, cellular and morphological mechanisms allows the scaffolding to integrate these modular variations...... is eventually attained when the embryo acquires the capacity to impose a number of developmental constraints on its constituting parts in a top-down direction. The acquisition of this capacity allows a semiotic threshold to emerge between the living cellular world and the underlying nonliving molecular world...... to the complexity of sign recognition proper of a cellular community. In this semiotic perspective, the apparent goal directness of any developmental strategy should no longer be accounted for by a predetermined genetic program, but by the gradual definition of the relationships selected amongst the ones...

  2. Evo-Devo of Amniote Integuments and Appendages

    OpenAIRE

    Wu, Ping; Hou, Lianhai; Plikus, Maksim; Hughes, Michael; Scehnet, Jeffrey; Suksaweang, Sanong; Widelitz, Randall B.; Jiang, Ting-Xin; Chuong, Cheng-Ming

    2004-01-01

    Integuments form the boundary between an organism and the environment. The evolution of novel developmental mechanisms in integuments and appendages allows animals to live in diverse ecological environments. Here we focus on amniotes. The major achievement for reptile skin is an adaptation to the land with the formation of a successful barrier. The stratum corneum enables this barrier to prevent water loss from the skin and allowed amphibian/reptile ancestors to go onto the land. Overlapping ...

  3. Kodymirus and the case for convergence of raptorial appendages in Cambrian arthropods

    Science.gov (United States)

    Lamsdell, James C.; Stein, Martin; Selden, Paul A.

    2013-09-01

    Kodymirus vagans Chlupáč and Havlíček in Sb Geol Ved Paleontol 6:7-20, 1965 is redescribed as an aglaspidid-like arthropod bearing a single pair of enlarged raptorial appendages, which are shown to be the second cephalic appendage. A number of early Palaeozoic arthropods, recognized from predominantly Cambrian Konservat-Lagerstätten, are known to have borne single pairs of large raptorial appendages. They are well established for the iconic yet problematic anomalocarids, the common megacheirans, and the ubiquitous bivalved Isoxys. Further taxa, such as fuxianhuiids and Branchiocaris, have been reported to have single pairs of specialized cephalic appendages, i.e., appendages differentiated from a largely homonomous limbs series, members of which act in metachronal motion. The homology of these raptorial appendages across these Cambrian arthropods has often been assumed, despite differences in morphology. Thus, anomalocaridids, for instance, have long multiarticulate "frontal appendages" consisting of many articles bearing an armature of paired serial spines, while megacheirans and Isoxys have short "great appendages" consisting of few articles with well-developed endites or elongate fingers. Homology of these appendages would require them to belong to the same cephalic segment. We argue based on morphological evidence that, to the contrary, the raptorial appendages of some of these taxa can be shown to belong to different cephalic segments and are the result of convergence in life habits. K. vagans is yet another important example for this, representing an instance for this morphology from a marginal marine environment.

  4. [Epiploic appendagitis: a rare cause of abdominal pain].

    Science.gov (United States)

    García-Marín, Andrés; Nofuentes-Riera, Carmen; Mella-Laborde, Mario; Pérez-López, Mercedes; Pérez-Bru, Susana; Rubio-Cerdido, José María

    2014-01-01

    Epiploic appendagitis is an atypical cause of abdominal pain whose knowledge could avoid diagnostic or treatment errors. Diagnosis has been performed with abdominal ultrasound or tomography with the only treatment being nonsteroidal anti-inflammatory drugs. To analyze patients diagnosed in our hospital. We performed a 4-year retrospective and descriptive study (March 2009-March 2013) of patients diagnosed with epiploic appendagitis in our hospital. Seventeen patients were included, 14 females and three males with a median age of 57 years. Symptom delay was 72 h. Abdominal pains were located in the left lower quadrant in 64.7% and right lower quadrant in 35.3% of patients. Blood test demonstrated leukocytes 6,300 (5,000-9,500), neutrophils 61.6% (57-65.8), and C reactive protein 1.5 (0.85-2.92). Diagnosis was confirmed with abdominal ultrasound or tomography in 88.2% and intraoperatively in 11.8%. Epiploic appendagitis was more frequent in women. Abdominal pain was located in the lower quadrant, more predominant in left than right. Blood tests were normal except for increased levels of C-reactive protein. Diagnosis was made mostly preoperatively due to imaging tests, avoiding unnecessary surgical intervention.

  5. [Implantation of Watchman™ occluder of the left atrial appendage. Tips and tricks].

    Science.gov (United States)

    Israel, Carsten W; Tschishow, Wladimir N; Ridjab, Denio; Kische, Stephan; Buddecke, Julia; Ince, Hüseyin

    2013-03-01

    The implantation of an occluder system for the left atrial appendage (LAA) represents an interesting alternative for patients with atrial fibrillation and a CHA2DS2-VASc-Score ≥ 2 who cannot take permanent anticoagulation for various reasons. As in other left cardiac interventions, there are potentially dangerous possibilities for complications that can limit the advantages of this therapy. This overview summarizes practical tips and tricks at the implantation of a Watchman™ occluder which may help to minimize the complication rate. These hints refer to peri-interventional anticoagulation as well as transseptal puncture (technique, imaging), exchange of catheters, left atrial pressure, intubation and fluoroscopy of the LAA, preparation of the device and sheath, delivery of the Watchman™ device, confirmation of optimal position, and partial or complete recapture. If these precautions are considered, the complication rate at implantation of a Watchman™ occluder should be  95 %.

  6. Mutational analysis of βCOP (Sec26p identifies an appendage domain critical for function

    Directory of Open Access Journals (Sweden)

    Cerione Richard A

    2008-01-01

    Full Text Available Abstract Background The appendage domain of the γCOP subunit of the COPI vesicle coat bears a striking structural resemblance to adaptin-family appendages despite limited primary sequence homology. Both the γCOP appendage domain and an equivalent region on βCOP contain the FxxxW motif; the conservation of this motif suggested the existence of a functional appendage domain in βCOP. Results Sequence comparisons in combination with structural prediction tools show that the fold of the COOH-terminus of Sec26p is strongly predicted to closely mimic that of adaptin-family appendages. Deletion of the appendage domain of Sec26p results in inviability in yeast, over-expression of the deletion construct is dominant negative and mutagenesis of this region identifies residues critical for function. The ArfGAP Glo3p was identified via suppression screening as a potential downstream modulator of Sec26p in a manner that is independent of the GAP activity of Glo3p but requires the presence of the COOH-terminal ISS motifs. Conclusion Together, these results indicate an essential function for the predicted βCOP appendage and suggest that both COPI appendages perform a biologically active regulatory role with a structure related to adaptin-family appendage domains.

  7. Left Atrial Appendage Closure Guided by 3D Printed Cardiac Reconstruction: Emerging Directions and Future Trends.

    Science.gov (United States)

    Pellegrino, Pier Luigi; Fassini, Gaetano; DI Biase, Matteo; Tondo, Claudio

    2016-06-01

    Percutaneous left atrial appendage (LAA) occlusion has emerged as an alternative therapeutic approach to medical therapy for stroke prevention in patients with atrial fibrillation. 3D printing is a novel technology able to create a patient specific model of any given anatomical portion of the heart. Herein we report the first 2 cases of LAA occlusion procedure with 2 different systems, the Wave Crest device (Coherex Medical, Inc., USA) and the Amplatzer Amulet device (St. Jude Medical, St. Paul, MN, USA), in which a 3D printed LAA model (Care Tronik, Prato, Italy) was used in a rehearse phase. Both patients had history of paroxysmal AF and previous transient ischemic attack (TIA) occurred during oral anticoagulation with correct INR. In the first patient the occlusive device was positioned within the LAA after a rehearse occlusion using the 3D printed LAA plus a 27 mm Coherex Wavecrest device, demonstrating a good compression and sealing, particularly considering a proximal lobe of the appendage. In the second patient an attempt with the 27 mm Amulet device delivered within the 3D printed LAA, based on angiography and transesophageal echocardiographic (TEE), revealed insufficient covering of the proximal part of LAA vestibule; the device was released only after a second test with the 31 mm Amulet demonstrating a good sealing. These 2 cases demonstrated that 3D model could help in finding the correct position within LAA, sizing the device and guiding the choice of the closure device despite the measurements provided by angiography and TEE. © 2016 Wiley Periodicals, Inc.

  8. [Regeneration of vertebrate appendage: an old experimental model to study stem cells in the adult].

    Science.gov (United States)

    Tawk, Marcel; Vriz, Sophie

    2003-04-01

    The application of stem cell therapy to cure degenerative diseases offers immense possibilities, but the research in this field is the subject of ethical debates raised by the question of destructive research on early human embryos. Stem cells taken in the adult constitute an alternative to human embryonic stem cells, but our knowledge on totipotent or pluripotent cells is currently insufficient. Furthermore, many questions must be solved before selection and differentiation of these cells in a given cellular type can be controlled on a routine basis. What are the molecular characteristics of an adult stem cell? What are the mechanisms involved in cell reprogramming? Which signals control stem cell replication and differentiation? Basic research activities must be carried out in order to clarify all these points. In this context, the regeneration of vertebrate appendages provides a model for this type of research. The regeneration process is defined by both the morphological and functional reconstruction of a part of a living organism, which has previously been destroyed. But why are some vertebrates able to regenerate complex structures and others apparently not? Among most vertebrates, the capacity to regenerate is limited to some tissues. It is however possible to observe the regeneration of appendages (limb, tail, fin, jaw, etc.) among several amphibians and fish. This regeneration leads to re-forming of the amputated part with a complete restoration of its shape, segmentation and function. Why is the amputation of limbs not followed by regeneration in mammals and birds: absence of stem cells, absence of recruitment signals for these cells, or absence of signal receptivity? This review constitutes a report on the current understanding of the basis of on regeneration of legs in tetrapods and of fins in fish with an emphasis in the role of the nervous system in this process.

  9. Primary epiploic appendagitis: Clinic and radiologic imaging findings

    Directory of Open Access Journals (Sweden)

    Mustafa Koplay

    2013-01-01

    Full Text Available Introduction: Primary epiploic appendagitis (PEA is arare and self-limiting disease that can mimicking acuteapendicitis and diverticulitis because of the clinical symptoms.The present retrospective study was discussed toclinical and radiologic characteristics of PEA.Methods: We reviewed the clinical, laboratory and computedtomography (CT findings of 10 patients with PEAbetween August 2010 and December 2012.Results: Ten patients (1 female and 9 males were diagnosedwith PEA. The average age was 37.1 (15-63years. Abdominal pain was localized to the right (2 cases,20% or left (7 cases, 70% lower quadrants and generalized(1 cases, 10%. All patients were afebrile. Only twopatients showed leukocytosis. There were gastrointestinalsymptoms such as nausea (3 patients and vomiting(1patient. In all cases, a pericolic fatty mass with a hyperattenuated ring was observed on CT. All of the patientswere treated symptomatic.Conlusion: In patients have atypical symptoms and laboratoryvalues with abdominal pain (especially left lowerabdominal pain, PEA should be considered in differentialdiagnosis. For correct diagnosis and avoid unnecessarysurgery, CT must be used in diagnosis because imagingfindings characteristic of the disease.Key words: Primary epiploic appendagitis, imaging, CT

  10. Evo-Devo of amniote integuments and appendages.

    Science.gov (United States)

    Wu, Ping; Hou, Lianhai; Plikus, Maksim; Hughes, Michael; Scehnet, Jeffrey; Suksaweang, Sanong; Widelitz, Randall; Jiang, Ting-Xin; Chuong, Cheng-Ming

    2004-01-01

    Integuments form the boundary between an organism and the environment. The evolution of novel developmental mechanisms in integuments and appendages allows animals to live in diverse ecological environments. Here we focus on amniotes. The major achievement for reptile skin is an adaptation to the land with the formation of a successful barrier. The stratum corneum enables this barrier to prevent water loss from the skin and allowed amphibian / reptile ancestors to go onto the land. Overlapping scales and production of beta-keratins provide strong protection. Epidermal invagination led to the formation of avian feather and mammalian hair follicles in the dermis. Both adopted a proximal - distal growth mode which maintains endothermy. Feathers form hierarchical branches which produce the vane that makes flight possible. Recent discoveries of feathered dinosaurs in China inspire new thinking on the origin of feathers. In the laboratory, epithelial - mesenchymal recombinations and molecular mis-expressions were carried out to test the plasticity of epithelial organ formation. We review the work on the transformation of scales into feathers, conversion between barbs and rachis and the production of "chicken teeth". In mammals, tilting the balance of the BMP pathway in K14 noggin transgenic mice alters the number, size and phenotypes of different ectodermal organs, making investigators rethink the distinction between morpho-regulation and pathological changes. Models on the evolution of feathers and hairs from reptile integuments are discussed. A hypothetical Evo-Devo space where diverse integument appendages can be placed according to complex phenotypes and novel developmental mechanisms is presented.

  11. Right Atrial Appendage Aneurysm in a Newborn Diagnosed with Fetal Echocardiography

    Science.gov (United States)

    Yartaşı Tik, Elif; Öztarhan, Kazım; Dedeoğlu, Reyhan; Çetinkaya, Merih

    2016-01-01

    Right atrial appendage aneurysm is a very rare condition which can be asymptomatic or can cause arrhythmia or life-threatening thromboembolism. We report a case of newborn with right atrial appendage aneurysm who was diagnosed with fetal echocardiography. Anticoagulant therapy was applied to prevent thromboembolism and he is still going on follow-up without any complaint. PMID:27703828

  12. High Accuracy Attitude Control System Design for Satellite with Flexible Appendages

    Directory of Open Access Journals (Sweden)

    Wenya Zhou

    2014-01-01

    Full Text Available In order to realize the high accuracy attitude control of satellite with flexible appendages, attitude control system consisting of the controller and structural filter was designed. When the low order vibration frequency of flexible appendages is approximating the bandwidth of attitude control system, the vibration signal will enter the control system through measurement device to bring impact on the accuracy or even the stability. In order to reduce the impact of vibration of appendages on the attitude control system, the structural filter is designed in terms of rejecting the vibration of flexible appendages. Considering the potential problem of in-orbit frequency variation of the flexible appendages, the design method for the adaptive notch filter is proposed based on the in-orbit identification technology. Finally, the simulation results are given to demonstrate the feasibility and effectiveness of the proposed design techniques.

  13. Strangulation Caused by a Small Bowel Epiploic Appendage: Report of a Case

    Directory of Open Access Journals (Sweden)

    Hiroshi Nemoto

    2008-07-01

    Full Text Available While many recent cases of colonic epiploic appendage causing acute abdomen have been reported, such appendages of the small bowel are extremely rare. We present a 59-year-old woman in whom a small bowel epiploic appendage caused volvulus. She presented with abdominal pain and vomiting in the absence of previous abdominal operations. A diagnosis of small bowel obstruction from strangulation was made. Laparotomy disclosed bloody peritoneal fluid and a closed loop of strangulated small intestine. An adherent band composed of an epiploic appendage and intestine had completely encircled a loop of jejunum, leading to obstruction. This band was released, and approximately 80 cm of gangrenous bowel was resected. Four epiploic appendages 5–6 cm in length were attached to the ileum at the mesenteric border, beginning at a point 70 cm proximal to the terminal ileum.

  14. Ferrofluid Appendages: Fluid Fins, a Numerical Investigation on the Feasibility of using Fluids as Shapeable Propulsive Appendages

    Directory of Open Access Journals (Sweden)

    M. A. Feizi Chekab

    2017-01-01

    Full Text Available The present study focuses on the feasibility of using fluids, and in particular magnetic fluids, as “Fluid Structures” in designing external appendages for the submerged bodies and propulsive fins as a practical example. After reviewing the literature of the mathematical simulation of magnetic fluids and their applications, the concept of “Fluid Structures” and “Fluid Fins” are briefly introduced. The validation of the numerical solver against analytical solutions is presented and acceptable error of 1.21% up to 2.29% is estimated. Subsequently, the initial shaping of the ferrofluid as an external fluid fin, using three combinations of internal magnetic actuators, is presented which makes the way to the oscillating motion of the obtained fin, by producing a periodically changing magnetic field. It is demonstrated that the shape of the fluid fin is almost the replica of the magnetic field. On the other hand, it is illustrated that a fluid fin with a size under 0.005 m on a circular submerged body of 1cm diameter could produce 0.0158 N force which is a high thrust force relative to the size of the body and the fin. Based on the obtained results, one may conclude that, when a “Fluid Fin” is capable of producing this amount of thrust, other fluid appendages could be scientifically contemplated and practically designed.

  15. Keratin Gene Mutations in Disorders of Human Skin and its Appendages

    Science.gov (United States)

    Chamcheu, Jean Christopher; Siddiqui, Imtiaz A.; Syed, Deeba N.; Adhami, Vaqar M.; Liovic, Mirjana; Mukhtar, Hasan

    2011-01-01

    Keratins, the major structural protein of all epithelia, are a diverse group of cytoskeletal scaffolding proteins that form intermediate filament networks, providing structural support to keratinocytes that maintain the integrity of the skin. Expression of keratin genes is usually regulated by differentiation of the epidermal cells within the stratifying squamous epithelium. Amongst the 54 known functional keratin genes in humans, about 21 different genes including hair and hair follicle-specific keratins have been associated with diverse hereditary disorders. The exact phenotype of each disease mostly reflects the spatial level of expression and types of the mutated keratin genes, the positions of the mutations as well as their consequences at sub-cellular levels. The identification of specific mutations in keratin disorders is the basis of our understanding that lead to reclassification, improved diagnosis with prognostic implications, prenatal testing and genetic counseling in severe cutaneous keratin genodermatoses. A disturbance in cutaneous keratins as a result of mutation(s) in the gene(s) that encode keratin intermediate filaments (KIF) causes keratinocytes and cutaneous tissue fragility, accounting for a large number of genetic disorders in human skin and its appendages. These diseases are characterized by a loss of structural integrity in keratinocytes expressing mutated keratins in vivo, often manifested as keratinocytes fragility (cytolysis), intra-epidermal blistering, hyperkeratosis, and keratin filament aggregation in severely affected tissues. Examples include epidermolysis bullosa simplex (EBS), keratinopathic ichthyosis (KPI), pachyonychia congenital (PC), monilethrix, steatocystoma multiplex and ichthyosis bullosa of Siemens (IBS). These keratins also have been identified to have roles in cell growth, apoptosis, tissue polarity, wound healing and tissue remodeling. PMID:21176769

  16. Thromboembolism Prevention via Transcatheter Left Atrial Appendage Closure with Transeosophageal Echocardiography Guidance

    Directory of Open Access Journals (Sweden)

    John Palios

    2014-01-01

    Full Text Available Atrial fibrillation (AF is an independent risk factor for stroke. Anticoagulation therapy has a risk of intracerebral hemorrhage. The use of percutaneous left atrial appendage (LAA closure devices is an alternative to anticoagulation therapy. Echocardiography has a leading role in LAA closure procedure in patient selection, during the procedure and during followup. A comprehensive echocardiography study is necessary preprocedural in order to identify all the lobes of the LAA, evaluate the size of the LAA ostium, look for thrombus or spontaneous echo contrast, and evaluate atrial anatomy, including atrial septal defect and patent foramen ovale. Echocardiography is used to identify potential cardiac sources of embolism, such as atrial septal aneurysm, mitral valve disease, and aortic debris. During the LAA occlusion procedure transeosophageal echocardiography provides guidance for the transeptal puncture and monitoring during the release of the closure device. Procedure-related complications can be evaluated and acceptable device release criteria such as proper position and seating of the occluder in the LAA, compression, and stability can be assessed. Postprocedural echocardiography is used for followup to assess the closure of the LAA ostium. This overview paper describes the emerging role of LAA occlusion procedure with transeosophageal echocardiography guidance as an alternative to anticoagulation therapy in patients with AF.

  17. Decellularized scaffolds containing hyaluronic acid and EGF for promoting the recovery of skin wounds.

    Science.gov (United States)

    Wu, Zhengzheng; Tang, Yan; Fang, Hongdou; Su, Zhongchun; Xu, Bin; Lin, Yongliang; Zhang, Peng; Wei, Xing

    2015-01-01

    There is no effective therapy for the treatment of deep and large area skin wounds. Decellularized scaffolds can be prepared from animal tissues and represent a promising biomaterial for investigation in tissue regeneration studies. In this study, MTT assay showed that epidermal growth factor (EGF) increased NIH3T3 cell proliferation in a bell-shaped dose response, and the maximum cell proliferation was achieved at a concentration of 25 ng/ml. Decellularized scaffolds were prepared from pig peritoneum by a series of physical and chemical treatments. Hyaluronic acid (HA) increased EGF adsorption to the scaffolds. Decellularized scaffolds containing HA sustained the release of EGF compared to no HA. Rabbits contain relatively large skin surface and are less expensive and easy to be taken care, so that a rabbit wound healing model was use in this study. Four full-thickness skin wounds were created in each rabbit for evaluation of the effects of the scaffolds on the skin regeneration. Wounds covered with scaffolds containing either 1 or 3 μg/ml EGF were significantly smaller than with vaseline oil gauzes or with scaffolds alone, and the wounds covered with scaffolds containing 1 μg/ml EGF recovered best among all four wounds. Hematoxylin-Eosin staining confirmed these results by demonstrating that significantly thicker dermis layers were also observed in the wounds covered by the decellularized scaffolds containing HA and either 1 or 3 μg/ml EGF than with vaseline oil gauzes or with scaffolds alone. In addition, the scaffolds containing HA and 1 μg/ml EGF gave thicker dermis layers than HA and 3 μg/ml EGF and showed the regeneration of skin appendages on day 28 post-transplantation. These results demonstrated that decellularized scaffolds containing HA and EGF could provide a promising way for the treatment of human skin injuries.

  18. Amplatzer Amulet left atrial appendage occluder entrapment through mitral valve.

    Science.gov (United States)

    González-Santos, Jose María; Arnáiz-García, María Elena; Arribas-Jiménez, Antonio; López-Rodríguez, Javier; Rodríguez-Collado, Javier; Vargas-Fajardo, María del Carmen; Dalmau-Sorlí, María José; Bueno-Codoñer, María Encarnación; Arévalo-Abascal, R Adolfo

    2013-11-01

    We report on a 77-year-old woman in whom percutaneous left atrial appendage (LAA) closure was performed. The patient had a left atrial myxoma resection 3 years previously, and 2 years later, she suffered a transient ischemic attack. Atrial fibrillation was detected and anticoagulation therapy was established. An episode of intracranial bleeding forced interruption of anticoagulation. Thus, percutaneous LAA closure with an Amplatzer Amulet LAA Occluder (St Jude Medical) was proposed. During the procedure, the LAA occluder migrated and became trapped in the mitral valve. Secondary massive mitral regurgitation and hemodynamic instability forced emergent cardiac surgery. Successful removal of the Amplatzer Amulet LAA Occluder was achieved. Copyright © 2013 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  19. Passive control of a falling sphere by elliptic-shaped appendages

    Science.gov (United States)

    Lācis, Uǧis; Olivieri, Stefano; Mazzino, Andrea; Bagheri, Shervin

    2017-03-01

    The majority of investigations characterizing the motion of single or multiple particles in fluid flows consider canonical body shapes, such as spheres, cylinders, discs, etc. However, protrusions on bodies—either surface imperfections or appendages that serve a function—are ubiquitous in both nature and applications. In this work, we characterize how the dynamics of a sphere with an axis-symmetric wake is modified in the presence of thin three-dimensional elliptic-shaped protrusions. By investigating a wide range of three-dimensional appendages with different aspect ratios and lengths, we clearly show that the sphere with an appendage may robustly undergo an inverted-pendulum-like (IPL) instability. This means that the position of the appendage placed behind the sphere and aligned with the free-stream direction is unstable, similar to how an inverted pendulum is unstable under gravity. Due to this instability, nontrivial forces are generated on the body, leading to turn and drift, if the body is free to fall under gravity. Moreover, we identify the aspect ratio and length of the appendage that induces the largest side force on the sphere, and therefore also the largest drift for a freely falling body. Finally, we explain the physical mechanisms behind these observations in the context of the IPL instability, i.e., the balance between surface area of the appendage exposed to reversed flow in the wake and the surface area of the appendage exposed to fast free-stream flow.

  20. Characterization of a novel Bacillus thuringiensis phenotype possessing multiple appendages attached to a parasporal body.

    Science.gov (United States)

    Ventura-Suárez, Antonio; Cruz-Camarillo, Ramón; Rampersad, Joanne; Ammons, David R; López-Villegas, Edgar O; Ibarra, Jorge E; Rojas-Avelizapa, Luz I

    2011-01-01

    Bacillus thuringiensis is a bacterium best known for its production of crystal-like bodies comprised of one or more Cry-proteins, which can be toxic to insects, nematodes or cancer cells. Although strains of B. thuringiensis have occasionally been observed with filamentous appendages attached to their spores, appendages in association with their parasporal bodies are extremely rare. Herein we report the characterization of Bt1-88, a bacterial strain isolated from the Caribbean that produces a spore-crystal complex containing six long appendages, each comprised of numerous thinner filaments approximately 10 nm in diameter and 2.5 μm in length. Each of the multi-filament appendages was attached to a single, small parasporal body located at one end of the bacterial spore. Biochemical tests, 16S rDNA gene sequencing, and the identification of two Cry proteins by partial protein sequencing (putatively Cry1A and Cry2A), unambiguously identified Bt1-88 as a strain of B. thuringiensis. Bt1-88 represents the second reported strain of B. thuringiensis possessing a parasporal body/appendage phenotype characterized by one or more long appendages, comprised of numerous filaments in association with a parasporal body. This finding suggests that Bt1-88 is a member of a new phenotypic class of B. thuringiensis, in which the parasporal body may perform a novel structural role through its association with multi-filament appendages.

  1. Potential uselessness and futility of left atrial appendage occlusion and patent foramen ovale closure in cardioembolic stroke.

    Science.gov (United States)

    Nicolosi, Gian L

    2017-02-16

    International guidelines indicate that interventional closure of left atrial appendage and patent foramen ovale may be considered in selected patients for stroke prevention. These procedures appear, however, from the published literature, at high risk of uselessness and futility in the single case, if not even capable to induce harm and adverse events. In fact, all reported systematic reviews and meta-analyses have not shown in a convincing manner the superiority of these procedures in stroke prevention, taking into account the occurrence of possible complications also, as compared with alternative medical treatment. On the basis of these considerations, it becomes very difficult to define always and unequivocally how adequate and complete was the information when given to each single candidate patient before the procedure by the Heart Team, the left atrial appendage occlusion Team or patent foramen ovale closure Team, potentially involved in conflict of interest. Before indicating these procedures, a complete diagnostic work-up should then be planned for each single patient to identify and treat not only one, but all concomitant risk factors and potential different cardioembolic sources. It could also be suggested to have, for each single candidate patient, a second independent opinion from physicians not involved in the procedure and possibly not operating in the same institution. This prudential approach could reduce in each single case the risk of uselessness, futility and even potential harm and adverse events of those procedures.

  2. Acute Appendagitis Presenting with Features of Appendicitis: Value of Abdominal CT Evaluation

    Directory of Open Access Journals (Sweden)

    Sukhpreet Dubb

    2008-05-01

    Full Text Available We report a case of acute appendagitis in a patient who presented initially with typical features of acute appendicitis. The diagnosis of acute appendagitis was made on pathognomonic signs on computed tomography (CT scan. Abdominal pain is a common surgical emergency. CT is not always done if there are clear features of acute appendicitis. The rare but important differential diagnosis of acute appendagitis must be borne in mind when dealing with patients with suspected acute appendicitis. A CT scan of the abdomen may avoid unnecessary surgery in these patients.

  3. [GISE/AIAC position paper on percutaneous left atrial appendage occlusion in patients with nonvalvular atrial fibrillation: recommendations for patient selection, facilities, competences, organizing and training requirements].

    Science.gov (United States)

    Berti, Sergio; Themistoclakis, Sakis; Santoro, Gennaro; De Ponti, Roberto; Danna, Paolo; Zecchin, Massimo; Bedogni, Francesco; Padeletti, Luigi

    2014-09-01

    Thromboembolism from the left atrial appendage is the most feared complication in patients with atrial fibrillation (AF). The cornerstone for the management of chronic nonvalvular AF is stroke reduction with oral anticoagulation (OAC). However, poor compliance, maintaining a narrow therapeutic window, and major side effects such as bleeding have severely limited its use, creating a therapeutic dilemma. About 20% of AF patients do not receive OAC due to contraindications and less than half of AF patients are not on OAC due to reluctance of the prescribing physician and/or patient non-compliance. Fortunately, over the past decade, the introduction of percutaneous approaches for left atrial appendage occlusion has offered a viable alternative to the management of nonvalvular AF in patients with OAC contraindication. Occlusion devices such as the Amplatzer Cardiac Plug and Watch man device have shown their noninferiority to OAC for stroke prophylaxis with less bleeding complications, while more recently some new devices have been introduced. The aim of this position paper is to review the most relevant clinical aspects of left atrial appendage occlusion from patient selection to periprocedural and follow-up management. In addition, the importance of a medical team and an organizational environment adequate to optimize all the steps of this procedure is discussed.

  4. Recent prospective of nanofiber scaffolds fabrication approaches for skin regeneration.

    Science.gov (United States)

    Ahmadi-Aghkand, Fateme; Gholizadeh-Ghaleh Aziz, Shiva; Panahi, Yunes; Daraee, Hadis; Gorjikhah, Fateme; Gholizadeh-Ghaleh Aziz, Sara; Hsanzadeh, Arash; Akbarzadeh, Abolfazl

    2016-11-01

    The largest organ of human body is skin, which acting as a barrier with immunologic, sensorial and protective functions. It is always in exposure to the external environment, which can result many different types of damage and injury with loss of variable volumes of extracellular matrix (ECM). For the treatment of skin lesions and damages, several approaches are now accessible, such as the application of allografts, autografts, and tissue-engineered substitutes, wound dressings and nanofiber scaffolds approaches. Even though proven clinically effective, these methods are still characterized by main drawbacks such as patient inadequate vascularization, morbidity, the inability to reproduce skin appendages, low adherence to the wound bed and high manufacturing costs. Advanced approaches based on nanofiber scaffolds approaches offer a permanent, viable and effective substitute to explain the drawbacks of skin regeneration and repair by combining growth factors, cells, and biomaterials and advanced biomanufacturing methods. This review details recent advances of nanofiber scaffolds in skin regeneration and repair strategies, and describes a synthesis method of nanofiber scaffolds.

  5. Procedural success and intra-hospital outcome related to left atrial appendage morphology in patients that receive an interventional left atrial appendage closure.

    Science.gov (United States)

    Fastner, Christian; Behnes, Michael; Sartorius, Benjamin; Wenke, Annika; El-Battrawy, Ibrahim; Ansari, Uzair; Gill, Ishar-Singh; Borggrefe, Martin; Akin, Ibrahim

    2017-08-01

    The interventional left atrial appendage (LAA) closure represents an emerging alternative to oral anticoagulation for stroke prevention in certain atrial fibrillation patients. Preliminary results have suggested high procedural success rates and fewer peri-interventional complications; however, there persists an insufficient understanding of the role of many underlying confounding variables (e.g., anatomical characteristics). It was investigated whether varying LAA morphologies influence procedural success as well as in-hospital outcome. Sixty-seven patients ineligible for long-term oral anticoagulation were included in this single-center, prospective, observational registry spanning from the years 2014 to 2016. Interventions were performed with the Watchman occluder (Boston Scientific, Natick, MA) or the Amplatzer Amulet (St. Jude Medical, St. Paul, MN), at the operator's discretion. Results derived from the data describing procedural success, fluoroscopy, and peri-interventional safety events were classified according to the presenting LAA morphology (cauliflower, cactus, windsock, and chicken wing). Rates of successful implantation were high across all groups (≥98%; P = 0.326). Surrogate parameters underlining procedural complexity like median total duration (P = 0.415), median fluoroscopy time (P = 0.459), median dose area product (P = 0.698), and the median amount of contrast agent (P = 0.076) demonstrated similar results across all groups. Likewise, the periprocedural complication rate was not significantly different and was mainly restricted to minor bleeding events. Irrespective of the varying morphological presentation of the LAA, the procedural success rates, interventional characteristics, and safety events did not significantly differ among patients receiving an interventional LAA closure. © 2017 Wiley Periodicals, Inc.

  6. Left atrial appendage in acute coronary syndromes: small but not insignificant

    Institute of Scientific and Technical Information of China (English)

    Mingpeng SHE

    2005-01-01

    @@ In this issue of Journal of Geriatric Cardiology, Dr.Piotrowski and colleagues explored the function of the left atrial appendage (LAA)-a small, blind-ended structure of the heart which has been often ignored by cardiologists.1

  7. Canonical Wnt signalling regulates epithelial patterning by modulating levels of laminins in zebrafish appendages.

    Science.gov (United States)

    Nagendran, Monica; Arora, Prateek; Gori, Payal; Mulay, Aditya; Ray, Shinjini; Jacob, Tressa; Sonawane, Mahendra

    2015-01-15

    The patterning and morphogenesis of body appendages - such as limbs and fins - is orchestrated by the activities of several developmental pathways. Wnt signalling is essential for the induction of limbs. However, it is unclear whether a canonical Wnt signalling gradient exists and regulates the patterning of epithelium in vertebrate appendages. Using an evolutionarily old appendage - the median fin in zebrafish - as a model, we show that the fin epithelium exhibits graded changes in cellular morphology along the proximo-distal axis. This epithelial pattern is strictly correlated with the gradient of canonical Wnt signalling activity. By combining genetic analyses with cellular imaging, we show that canonical Wnt signalling regulates epithelial cell morphology by modulating the levels of laminins, which are extracellular matrix components. We have unravelled a hitherto unknown mechanism involved in epithelial patterning, which is also conserved in the pectoral fins - evolutionarily recent appendages that are homologous to tetrapod limbs.

  8. Strangulation and Necrosis of an Epiploic Appendage of the Sigmoid Colon in a Right Inguinal Hernia

    Directory of Open Access Journals (Sweden)

    Yuri N. Shiryajev

    2013-01-01

    Full Text Available An epiploic appendage of the sigmoid colon is considered to be an unusual type of inguinal hernia content. The strangulation of a sigmoid colon appendage into a right inguinal hernia is exclusively rare. We present a case of an 81-year-old female patient with severe cardiovascular comorbidities who was urgently admitted after an episode of strangulation and subsequent spontaneous reduction of a right inguinal hernia. The condition of the patient was stable, and an urgent operation was not indicated for three days after admission. However, we had to operate because the hernia strangulation recurred. In the hernia sac, a free fatty body (a separated and saponified epiploic appendage of the colon and a strangulated epiploic appendage of dolichosigmoid, with signs of necrosis, were found. Removal of the free fatty body and necrotic epiploic appendage and subsequent anterior-wall inguinal hernioplasty were successfully performed. In the world literature, this case may be the first report of a sigmoid epiploic appendage strangulation in a right inguinal hernia that is well documented by photography.

  9. Development of keratin–chitosan–gelatin composite scaffold for soft tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Kakkar, Prachi [Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India); Verma, Sudhanshu; Manjubala, I. [Biomedical Engineering Division, School of Bio Sciences and Technology, VIT University, Vellore 632014 (India); Madhan, B., E-mail: bmadhan76@yahoo.co.in [Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600020 (India)

    2014-12-01

    Keratin has gained much attention in the recent past as a biomaterial for wound healing owing to its biocompatibility, biodegradability, intrinsic biological activity and presence of cellular binding motifs. In this paper, a novel biomimetic scaffold containing keratin, chitosan and gelatin was prepared by freeze drying method. The prepared keratin composite scaffold had good structural integrity. Fourier Transform Infrared (FTIR) spectroscopy showed the retention of the native structure of individual biopolymers (keratin, chitosan, and gelatin) used in the scaffold. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) results revealed a high thermal denaturation temperature of the scaffold (200–250 °C). The keratin composite scaffold exhibited tensile strength (96 kPa), compression strength (8.5 kPa) and water uptake capacity (> 1700%) comparable to that of a collagen scaffold, which was used as control. The morphology of the keratin composite scaffold observed using a Scanning Electron Microscope (SEM) exhibited good porosity and interconnectivity of pores. MTT assay using NIH 3T3 fibroblast cells demonstrated that the cell viability of the keratin composite scaffold was good. These observations suggest that the keratin–chitosan–gelatin composite scaffold is a promising alternative biomaterial for tissue engineering applications. - Highlights: • Fabrication of novel Keratin-Chitosan-Gelatin composite scaffold • Keratin composite scaffold shows excellent water uptake capacity and porosity • Keratin composite scaffold shows good thermal and physical stability • Biocompatibility of the developed scaffold is comparable to collagen scaffolds • Developed scaffold is a promising material for soft tissue engineering applications.

  10. Cardiac embolism after implantable cardiac defibrillator shock in non-anticoagulated atrial fibrillation: The role of left atrial appendage occlusion.

    Science.gov (United States)

    Freixa, Xavier; Andrea, Rut; Martín-Yuste, Victoria; Fernández-Rodríguez, Diego; Brugaletta, Salvatore; Masotti, Mónica; Sabaté, Manel

    2014-04-26

    Cardioembolic events are one of the most feared complications in patients with non-valvular atrial fibrillation (NVAF) and a formal contraindication to oral anticoagulation (OAC). The present case report describes a case of massive peripheral embolism after an implantable cardiac defibrillator (ICD) shock in a patient with NVAF and a formal contraindication to OAC due to previous intracranial hemorrhage. In order to reduce the risk of future cardioembolic events, the patient underwent percutaneous left atrial appendage (LAA) occlusion. A 25 mm Amplatzer™ Amulet was implanted and the patient was discharged the following day without complications. The potential risk of thrombus dislodgement after an electrical shock in patients with NVAF and no anticoagulation constitutes a particular scenario that might be associated with an additional cardioembolic risk. Although LAA occlusion is a relatively new technique, its usage is rapidly expanding worldwide and constitutes a very valid alternative for patients with NVAF and a formal contraindication to OAC.

  11. Skin appendageal immune reactivity in a case of cutaneous lupus

    Directory of Open Access Journals (Sweden)

    Ana Maria Abreu Velez

    2011-10-01

    Full Text Available Background: Discoid lupus erythematosus is a cutaneous disease with a worldwide distribution, and its pathogenesis remains unclear. Case Report: A 41 year old male was evaluated for hair loss, in patches on the scalp. We studied selected adaptor proteins expressed in T, natural killer, neutrophil and mast cells; these proteins are important mediators for antigen receptor signaling in situ. Methods: Skin biopsies for hematoxylin and eosin examination, as well as for direct immunofluorescence and immunohistochemistry analysis were performed. Results: Hematoxylin and eosin staining demonstrated classic features of lupus with focal dermal scarring; epidermal atrophy was noted, with lymphohistiocytic infiltrates around the skin appendages. Direct immunofluoresence revealed classic, lupus band positive staining along the dermal/epidermal junction. In addition, immune reactants were identified in neurovascular areas, and around pilosebaceous units. Immunohistochemistry staining showed positive staining for the T-cell antigen receptor zeta chain, the linker for activation of T cells, myeloperoxidase, cyclo-oxygenase 2, melanoma-associated antigen 1, B cell leukemia/lymphoma-2 associated X protein, and BCL-2 markers. The positive staining was observed within the dermal inflammatory infiltrate, around pilosebaceous units, upper dermal blood vessels, and focally within eccrine sweat glands. Conclusions: The pathobiology of cutaneous lupus involves not only the epidermis, but also dermal pilosebaceous units, eccrine sweat glands and blood vessels. Further studies are recommended, especially in the light of presented data regarding T cell activation and proapototic molecules.

  12. Rationale of cerebral protection devices in left atrial appendage occlusion.

    Science.gov (United States)

    Meincke, Felix; Spangenberg, Tobias; Kreidel, Felix; Frerker, Christian; Virmani, Renu; Ladich, Elena; Kuck, Karl-Heinz; Ghanem, Alexander

    2017-01-01

    Aims of this case-series were to assess the feasibility of cerebral protection devices in interventional left atrial appendage occlusion (iLAAO) procedures and to yield insight into the pathomorphological correlate of early, procedural cerebral embolization during iLAAO. Five consecutive patients underwent iLLO flanked by the Sentinel CPS® (Claret Medical, Inc., Santa Rosa, CA) cerebral protection system. Placement and recapture of the Sentinel(®) device as well as the iLAAO were successful and safe in all cases. Histomorphometric analysis of the collected filters showed embolized debris in all patients. Acute thrombus was found in three patients, organizing thrombus in four. Interestingly, two patients had endocardial or myocardial tissue in their filters. Cerebral protection during iLAAO with the Sentinel CPS(®) device is feasible. Furthermore, this dataset identifies the formation and embolization of thrombus and cardiac tissue as emboligeneic sources and potential future targets to reduce procedural complications. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  13. Photodynamic Therapy and Skin Appendage Disorders: A Review

    Science.gov (United States)

    Megna, Matteo; Fabbrocini, Gabriella; Marasca, Claudio; Monfrecola, Giuseppe

    2017-01-01

    Photodynamic therapy (PDT) is a noninvasive treatment that utilizes light treatment along with application of a photosensitizing agent. In dermatology, PDT is commonly used and approved for the treatment of oncological conditions such as actinic keratosis, Bowen disease and superficial basal cell carcinoma. In the last 2 decades however, PDT has also been used for the treatment of several nonneoplastic dermatological diseases. The present review summarizes published data on PDT application in skin appendage disorders. Our literature review shows that: (a) PDT may be a suitable treatment for acne, folliculitis decalvans, hidradenitis suppurativa, nail diseases, and sebaceous hyperplasia; (b) there is a lack of agreement on PDT features (type, concentrations and incubation period of used substances, number and frequency of PDT sessions, optimal parameters of light sources, and patient characteristics [e.g., failure to previous treatments, disease severity, body surface area involved, etc.] which should guide PDT use in these diseases); (c) further research is needed to establish international guidelines helping dermatologists to choose PDT for the right patient at the right time.

  14. Isomerism of the atrial appendages in the fetus.

    Science.gov (United States)

    Ho, S Y; Cook, A; Anderson, R H; Allan, L D; Fagg, N

    1991-01-01

    Thirty hearts from fetuses with visceral heterotaxy were examined to determine the range of cardiac malformations. By examining the morphology of the atrial appendages, 20 hearts were identified as having left isomerism (67%) and 10 hearts right isomerism (33%). Fifteen of the hearts with left isomerism had biventricular atrioventricular connections and five had univentricular atrioventricular connections. All 10 hearts with right isomerism had biventricular atrioventricular connections. Flow to the pulmonary arteries was obstructed or occluded in 6 hearts with left isomerism (30%) and 7 hearts with right isomerism (70%). Obstruction to aortic flow was present in 4 hearts with left isomerism (20%). Anomalies of the systemic and pulmonary veins were common in both groups. The suprarenal portion of the inferior caval vein was interrupted in 11 hearts with left isomerism (55%) and 1 heart with right isomerism (10%). Atrioventricular septal defect was present in 13 hearts with left isomerism (65%) and 9 hearts with right isomerism (90%). The arrangement of the liver or stomach in each group was not consistent, nor was the status of the spleen. The constellations of cardiac malformations in both groups corresponded to those known in postnatal life and similar guidelines for their identification were applicable.

  15. 3D Printing of Scaffolds for Tissue Regeneration Applications

    Science.gov (United States)

    Do, Anh-Vu; Khorsand, Behnoush; Geary, Sean M.; Salem, Aliasger K.

    2015-01-01

    The current need for organ and tissue replacement, repair and regeneration for patients is continually growing such that supply is not meeting the high demand primarily due to a paucity of donors as well as biocompatibility issues that lead to immune rejection of the transplant. In an effort to overcome these drawbacks, scientists working in the field of tissue engineering and regenerative medicine have investigated the use of scaffolds as an alternative to transplantation. These scaffolds are designed to mimic the extracellular matrix (ECM) by providing structural support as well as promoting attachment, proliferation, and differentiation with the ultimate goal of yielding functional tissues or organs. Initial attempts at developing scaffolds were problematic and subsequently inspired a growing interest in 3D printing as a mode for generating scaffolds. Utilizing three-dimensional printing (3DP) technologies, ECM-like scaffolds can be produced with a high degree of complexity and precision, where fine details can be included at a micron level. In this review, we discuss the criteria for printing viable and functional scaffolds, scaffolding materials, and 3DP technologies used to print scaffolds for tissue engineering. A hybrid approach, employing both natural and synthetic materials, as well as multiple printing processes may be the key to yielding an ECM-like scaffold with high mechanical strength, porosity, interconnectivity, biocompatibility, biodegradability, and high processability. Creating such biofunctional scaffolds could potentially help to meet the demand by patients for tissues and organs without having to wait or rely on donors for transplantation. PMID:26097108

  16. Suppression of apoptosis by enhanced protein adsorption on polymer/hydroxyapatite composite scaffolds

    OpenAIRE

    2007-01-01

    Bone tissue engineering is a promising alternative to bone grafting. Scaffolds play a critical role in tissue engineering. Composite scaffolds made of biodegradable polymers and bone mineral-like inorganic compounds have been reported to be advantageous over plain polymer scaffolds by our group and others. In this study, we compared cellular and molecular events during the early periods of osteoblastic cell culture on poly(l-lactic acid)/hydroxyapatite (PLLA/HAP) composite scaffolds with thos...

  17. Keratin gene mutations in disorders of human skin and its appendages.

    Science.gov (United States)

    Chamcheu, Jean Christopher; Siddiqui, Imtiaz A; Syed, Deeba N; Adhami, Vaqar M; Liovic, Mirjana; Mukhtar, Hasan

    2011-04-15

    Keratins, the major structural protein of all epithelia are a diverse group of cytoskeletal scaffolding proteins that form intermediate filament networks, providing structural support to keratinocytes that maintain the integrity of the skin. Expression of keratin genes is usually regulated by differentiation of the epidermal cells within the stratifying squamous epithelium. Amongst the 54 known functional keratin genes in humans, about 22 different genes including, the cornea, hair and hair follicle-specific keratins have been implicated in a wide range of hereditary diseases. The exact phenotype of each disease usually reflects the spatial expression level and the types of mutated keratin genes, the location of the mutations and their consequences at sub-cellular levels as well as other epigenetic and/or environmental factors. The identification of specific pathogenic mutations in keratin disorders formed the basis of our understanding that led to re-classification, improved diagnosis with prognostic implications, prenatal testing and genetic counseling in severe keratin genodermatoses. Molecular defects in cutaneous keratin genes encoding for keratin intermediate filaments (KIFs) causes keratinocytes and tissue-specific fragility, accounting for a large number of genetic disorders in human skin and its appendages. These diseases are characterized by keratinocytes fragility (cytolysis), intra-epidermal blistering, hyperkeratosis, and keratin filament aggregation in severely affected tissues. Examples include epidermolysis bullosa simplex (EBS; K5, K14), keratinopathic ichthyosis (KPI; K1, K2, K10) i.e. epidermolytic ichthyosis (EI; K1, K10) and ichthyosis bullosa of Siemens (IBS; K2), pachyonychia congenita (PC; K6a, K6b, K16, K17), epidermolytic palmo-plantar keratoderma (EPPK; K9, (K1)), monilethrix (K81, K83, K86), ectodermal dysplasia (ED; K85) and steatocystoma multiplex. These keratins also have been identified to have roles in apoptosis, cell proliferation

  18. Expression of the Lhx genes apterous and lim1 in an errant polychaete: implications for bilaterian appendage evolution, neural development, and muscle diversification

    Directory of Open Access Journals (Sweden)

    Winchell Christopher J

    2013-02-01

    those generating distinct neuronal identities in fly and mouse nerve cords. Expression of apterous and lim1 in discrete components of developing parapodia is intriguing but does not map to comparable expression of these genes in developing arthropod appendages. Thus, annelid and arthropod appendage development apparently evolved, in part, via distinct co-option of the neuronal regulatory architecture. These divergent patterns of apterous and lim1 activity seemingly reflect de novo origins of parapodia and arthropodia, although we discuss alternative hypotheses.

  19. Evolution of nubbin function in hemimetabolous and holometabolous insect appendages

    Science.gov (United States)

    Turchyn, Nataliya; Chesebro, John; Hrycaj, Steven; Couso, Juan P.; Popadić, Aleksandar

    2011-01-01

    Insects display a whole spectrum of morphological diversity, which is especially noticeable in the organization of their appendages. A recent study in a hemipteran, Oncopeltus fasciatus (milkweed bug), showed that nubbin (nub) affects antenna morphogenesis, labial patterning, the length of the femoral segment in legs, and the formation of a limbless abdomen. To further determine the role of this gene in the evolution of insect morphology, we analyzed its functions in two additional hemimetabolous species, Acheta domesticus (house cricket) and Periplaneta americana (cockroach), and re-examined its role in Drosophila. While both Acheta and Periplaneta nub-RNAi first nymphs develop crooked antennae, no visible changes are observed in the morphologies of their mouthparts and abdomen. Instead, the main effect is seen in legs. The joint between the tibia and first tarsomere (Ta-1) is lost in Acheta, which in turn, causes a fusion of these two segments and creates a chimeric nub-RNAi tibia-tarsus that retains a tibial identity in its proximal half and acquires a Ta-1 identity in its distal half. Similarly, our re-analysis of nub function in Drosophila reveals that legs lack all true joints and the fly tibia also exhibits a fused tibia and tarsus. Finally, we observe a similar phenotype in Periplaneta except that it encompasses different joints (coxa-trochanter and femur-tibia), and in this species we also show that nub expression in the legs is regulated by Notch signaling, as had previously been reported in flies and spiders. Overall, we propose that nub acts downstream of Notch on the distal part of insect leg segments to promote their development and growth, which in turn is required for joint formation. Our data represent the first functional evidence defining a role for nub in leg segmentation and highlight the varying degrees of its involvement in this process across insects. PMID:21708143

  20. Evolution of nubbin function in hemimetabolous and holometabolous insect appendages.

    Science.gov (United States)

    Turchyn, Nataliya; Chesebro, John; Hrycaj, Steven; Couso, Juan P; Popadić, Aleksandar

    2011-09-01

    Insects display a whole spectrum of morphological diversity, which is especially noticeable in the organization of their appendages. A recent study in a hemipteran, Oncopeltus fasciatus (milkweed bug), showed that nubbin (nub) affects antenna morphogenesis, labial patterning, the length of the femoral segment in legs, and the formation of a limbless abdomen. To further determine the role of this gene in the evolution of insect morphology, we analyzed its functions in two additional hemimetabolous species, Acheta domesticus (house cricket) and Periplaneta americana (cockroach), and re-examined its role in Drosophila melanogaster (fruit fly). While both Acheta and Periplaneta nub-RNAi first nymphs develop crooked antennae, no visible changes are observed in the morphologies of their mouthparts and abdomen. Instead, the main effect is seen in legs. The joint between the tibia and first tarsomere (Ta-1) is lost in Acheta, which in turn, causes a fusion of these two segments and creates a chimeric nub-RNAi tibia-tarsus that retains a tibial identity in its proximal half and acquires a Ta-1 identity in its distal half. Similarly, our re-analysis of nub function in Drosophila reveals that legs lack all true joints and the fly tibia also exhibits a fused tibia and tarsus. Finally, we observe a similar phenotype in Periplaneta except that it encompasses different joints (coxa-trochanter and femur-tibia), and in this species we also show that nub expression in the legs is regulated by Notch signaling, as had previously been reported in flies and spiders. Overall, we propose that nub acts downstream of Notch on the distal part of insect leg segments to promote their development and growth, which in turn is required for joint formation. Our data represent the first functional evidence defining a role for nub in leg segmentation and highlight the varying degrees of its involvement in this process across insects.

  1. Left atrial appendage occlusion: initial experience with the Amplatzer™ Amulet™.

    Science.gov (United States)

    Freixa, Xavier; Abualsaud, Ali; Chan, Jason; Nosair, Mohamed; Tzikas, Apostolos; Garceau, Patrick; Basmadjian, Arsène; Ibrahim, Réda

    2014-07-01

    The Amplatzer™ Amulet™ (Amulet) is the evolution of the Amplatzer™ Cardiac Plug, a dedicated device for percutaneous left atrial appendage (LAA) occlusion. The new device has been designed to facilitate the implantation process, improve the sealing performance and further reduce the risk of complications. The objective of the study was to describe the initial experience with the Amplatzer Amulet for percutaneous LAA occlusion. This was a prospective single-center study of patients undergoing percutaneous LAA occlusion. The indication for LAA closure was a formal contraindication for oral anticoagulation or previous history of stroke due to INR lability. All procedures were done under general anesthesia and transesophageal echocardiography (TEE) guidance. Transthoracic echocardiography was performed 24h after the procedure in order to rule out procedural complications before discharge. Further follow-up was done with a clinical visit and TEE at 1-3 months. Between July-2012 and June-2013, 25 patients with a mean CHA2DS2-VASC of 4.3 ± 1.7 underwent LAA occlusion with the Amplatzer Amulet. The device was successfully implanted in 24 patients (96%) without any procedural stroke, pericardial effusion or device embolization. None of the patients presented any clinical event at follow-up. Follow-up TEE showed complete LAA sealing in all patients with no residual leaks >3mm and no device embolization. One patient (4.1%) presented a device thrombosis at follow-up without clinical expression. In this initial series of patients, the Amulet showed a remarkable acute and short-term performance in terms of feasibility and safety as depicted by the high successful implantation rate and the low incidence of complications. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. Attitude maneuver of liquid-filled spacecraft with a flexible appendage by momentum wheel

    Institute of Scientific and Technical Information of China (English)

    Dan-Dan Yang; Bao-Zeng Yue; Wen-Jun Wu; Xiao-Juan Song; Le-Mei Zhu

    2012-01-01

    Attitude maneuver of liquid-filled spacecraft with an appendage as a cantilever beam by momentum wheel is studied.The dynamic equations are derived by conservation of angular momentum and force equilibrium principle.A feedback control strategy of the momentum wheel is applied for the attitude maneuver.The residual nutation of the spacecraft in maneuver process changes with some chosen parameters,such as steady state time,locations of the liquid container and the appendage,and appendage parameters.The results indicate that locations in the second and fourth quadrants of the body-fixed coordinate system and the second quadrant of the wall of the main body are better choices forplacing the liquid containers and the appendage than other locations if they can be placed randomly.Higher density and thicker cross section are better for lowering the residual nutation if they can be changed.Light appendage can be modeled as a rigid body,which results in a larger residual nutation than a flexible model though.The residual nutation decreases with increasing absolute value of the initial sloshing angular height.

  3. Relative uptake of minoxidil into appendages and stratum corneum and permeation through human skin in vitro.

    Science.gov (United States)

    Grice, Jeffrey E; Ciotti, Susan; Weiner, Norman; Lockwood, Peter; Cross, Sheree E; Roberts, Michael S

    2010-02-01

    We examined uptake of the model therapeutic agent, minoxidil, into appendages, stratum corneum (SC), and through human skin, under the influence of different vehicles. Quantitative estimation of therapeutic drug deposition into all three areas has not previously been reported. Finite doses of minoxidil (2%, w/v) in formulations containing varying amounts of ethanol, propylene glycol (PG), and water (60:20:20, 80:20:0, and 0:80:20 by volume, respectively) were used. Minoxidil in SC (by tape stripping), appendages (by cyanoacrylate casting), and receptor fluid was determined by liquid scintillation counting. At early times (30 min, 2 h), ethanol-containing formulations (60:20:20 and 80:20:0) caused significantly greater minoxidil retention in SC and appendages, compared to the formulation lacking ethanol (0:80:20). A significant increase in minoxidil receptor penetration occurred with the PG-rich 0:80:20 formulation after 12 h. We showed that deposition of minoxidil into appendages, SC, and skin penetration into receptor fluid were similar in magnitude. Transport by the appendageal route is likely to be a key determinant of hair growth promotion by minoxidil. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association.

  4. The dynamics of scaffolding

    NARCIS (Netherlands)

    Van Geert, P. L. C.; Steenbeek, H.W.

    2005-01-01

    In this article we have reinterpreted a relatively standard definition of scaffolding in the context of dynamic systems theory. Our main point is that scaffolding cannot be understood outside the context of a dynamic approach of learning and (formal or informal) teaching. We provide a dynamic system

  5. 3D Printing of Scaffolds for Tissue Regeneration Applications.

    Science.gov (United States)

    Do, Anh-Vu; Khorsand, Behnoush; Geary, Sean M; Salem, Aliasger K

    2015-08-26

    The current need for organ and tissue replacement, repair, and regeneration for patients is continually growing such that supply is not meeting demand primarily due to a paucity of donors as well as biocompatibility issues leading to immune rejection of the transplant. In order to overcome these drawbacks, scientists have investigated the use of scaffolds as an alternative to transplantation. These scaffolds are designed to mimic the extracellular matrix (ECM) by providing structural support as well as promoting attachment, proliferation, and differentiation with the ultimate goal of yielding functional tissues or organs. Initial attempts at developing scaffolds were problematic and subsequently inspired an interest in 3D printing as a mode for generating scaffolds. Utilizing three-dimensional printing (3DP) technologies, ECM-like scaffolds can be produced with a high degree of complexity, where fine details can be included at a micrometer level. In this Review, the criteria for printing viable and functional scaffolds, scaffolding materials, and 3DP technologies used to print scaffolds for tissue engineering are discussed. Creating biofunctional scaffolds could potentially help to meet the demand by patients for tissues and organs without having to wait or rely on donors for transplantation.

  6. Left atrial appendage closure in patients with intracranial haemorrhage and atrial fibrillation.

    Science.gov (United States)

    Fayos-Vidal, F; Arzamendi-Aizpurua, D; Millán-Álvarez, X; Guisado-Alonso, D; Camps-Renom, P; Prats-Sánchez, L; Martínez-Domeño, A; Delgado-Mederos, R; Martí-Fàbregas, J

    2017-08-30

    The use of oral anticoagulants in patients with a history of atrial fibrillation (AF) and intracranial haemorrhage (ICH) is controversial on account of the risk of haemorrhagic stroke recurrence. This study presents our experience regarding the safety and efficacy of percutaneous left atrial appendage closure (LAAC), an alternative to anticoagulation in these patients. We conducted a retrospective, single-centre, observational study. LAAC was performed in patients with a history of ICH and non-valvular AF. Risk of ischaemic and haemorrhagic events was estimated using the CHA2DS2-VASc and HAS-BLED scales. We recorded periprocedural complications, IHC recurrence, cerebral/systemic embolism, mortality and use of antithrombotic drugs following the procedure. LAAC was performed in 9 patients (7 men, 2 women) using the AMPLATZER Amulet device in 7 cases and the AMPLATZER Cardiac Plug device in 2. Mean age was 72.7±8.2 years. Time between ICH and LAAC was less than one month in 5 patients and more than one month in 4 patients. Median CHA2DS2-VASc score was 4 (interquartile range of 2.5). Median HAS-BLED score was 3 (interquartile range of 0). No periprocedural complications were recorded. All patients received single anti-platelet therapy (clopidogrel in 5 patients, aspirin in 4) after the procedure; 5 patients received this treatment for 6 months and 4 received it indefinitely. No ischaemic or haemorrhagic events were recorded during follow-up (mean duration of 15 months). In our series, LAAC was found to be safe and effective in patients with a history of ICH who required anticoagulation due to AF. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Cardiac CT angiography for device surveillance after endovascular left atrial appendage closure.

    Science.gov (United States)

    Saw, Jacqueline; Fahmy, Peter; DeJong, Peggy; Lempereur, Mathieu; Spencer, Ryan; Tsang, Michael; Gin, Kenneth; Jue, John; Mayo, John; McLaughlin, Patrick; Nicolaou, Savvas

    2015-11-01

    Left atrial appendage (LAA) device imaging after endovascular closure is important to assess for device thrombus, residual leak, positioning, surrounding structures, and pericardial effusion. Cardiac CT angiography (CCTA) is well suited to assess these non-invasively. We report our consecutive series of non-valvular atrial fibrillation patients who underwent CCTA post-LAA closure with Amplatzer Cardiac Plug (ACP), Amulet (second generation ACP), or WATCHMAN devices. Patients underwent CCTA typically 1-6 months post-implantation. Prospective cardiac-gated CCTA was performed with Toshiba 320-detector or Siemens 2nd generation 128-slice dual-source scanners, and images interpreted with VitreaWorkstation™. GFR Amulet, 18 WATCHMAN). Average age was 75.5 ± 8.9 years, mean CHADS2 score 3.1 ± 1.3, and CHADS-VASc score 4.9 ± 1.6. All had contraindications to oral anticoagulation. Post-procedure, 41 (91.1%) were discharged on DAPT. There was one device embolization (ACP, successfully retrieved percutaneously) and one thrombus (WATCHMAN, resolved with 3 months of warfarin). There were two pericardial effusions, both pre-existing and not requiring intervention. Residual leak (patency) was seen in 28/44 (63.6%), and the mechanisms of leak were readily identified by CCTA (off-axis device, gaps at orifice, or fabric leak). Mean follow-up was 1.2 ± 1.1year, with no death, stroke, or systemic embolism. CCTA appears to be a feasible alternative to transoesophageal echocardiography for post-LAA device surveillance to evaluate for device thrombus, residual leak, embolization, position, and pericardial effusion. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  8. Skin appendage-derived stem cells: cell biology and potential for wound repair.

    Science.gov (United States)

    Xie, Jiangfan; Yao, Bin; Han, Yutong; Huang, Sha; Fu, Xiaobing

    2016-01-01

    Stem cells residing in the epidermis and skin appendages are imperative for skin homeostasis and regeneration. These stem cells also participate in the repair of the epidermis after injuries, inducing restoration of tissue integrity and function of damaged tissue. Unlike epidermis-derived stem cells, comprehensive knowledge about skin appendage-derived stem cells remains limited. In this review, we summarize the current knowledge of skin appendage-derived stem cells, including their fundamental characteristics, their preferentially expressed biomarkers, and their potential contribution involved in wound repair. Finally, we will also discuss current strategies, future applications, and limitations of these stem cells, attempting to provide some perspectives on optimizing the available therapy in cutaneous repair and regeneration.

  9. The chelifores of sea spiders (Arthropoda, Pycnogonida) are the appendages of the deutocerebral segment.

    Science.gov (United States)

    Brenneis, Georg; Ungerer, Petra; Scholtz, Gerhard

    2008-01-01

    Within the last decade, gene expression patterns and neuro-anatomical data have led to a new consensus concerning the long-debated association between anterior limbs and neuromeres in the arthropod head. According to this new view, the first appendage in all extant euarthropods is innervated by the second neuromere, the deutocerebrum, whereas the anterior-most head region bearing the protocerebrum lacks an appendage. This stands in contrast to the clearly protocerebrally targeted "antennae" of Onychophora and to some evidence for protocerebral limbs in fossil euarthropod representatives. Yet, the latter "frontal appendages" or "primary antennae" have most likely been reduced or lost in the lineage, leading to extant taxa. Surprisingly, a recent neuro-anatomical study on a pycnogonid challenged this evolutionary scenario, reporting a protocerebral innervation of the first appendages, the chelifores. However, this interpretation was soon after questioned by Hox gene expression data. To re-evaluate the unresolved controversy, we analyzed neuro-anatomy and neurogenesis in four pycnogonid species using immunohistochemical techniques. We clearly show the postprotocerebral innervation of the chelifores, which is resolved as the plesiomorphic condition in pycnogonids when evaluated against a recently published comprehensive phylogeny. By providing direct morphological support for the deutocerebral status of the cheliforal ganglia, we reconcile morphological and gene expression data and argue for a corresponding position between the anterior-most appendages in all extant euarthropods. Consequently, other structures have to be scrutinized to illuminate the fate of a presumptive protocerebral appendage in recent euarthropods. The labrum and the "frontal filaments" of some crustaceans are possible candidates for this approach.

  10. [Giant congenital intrapericardial left atrial appendage aneurysm: about a case and review of the literature].

    Science.gov (United States)

    Zhari, Bouchra; Bellamlih, Habib; Boumdine, Hassan; Amil, Touriya; Bamous, Mehdi; En-Nouali, Hassan

    2016-01-01

    Left atrial appendage aneurysm is a very rare heart anomaly. It may be congenital or acquired, secondary to inflammatory or degenerative processes. Most cases are asymptomatic. The prevalence of these lesions in pediatric age has been very rarely reported. As it can cause potentially fatal arrhythmias or thrombus, surgery is required immediately after diagnosis. This study reports the case of a 14-year-old boy with rapidly progressive dyspnea, palpitations, sensation of repetitive dizziness and fainting, in whom congenital left atrial appendage aneurysm was detected. Diagnosis was based on coronary CTA data. The patient was successfully treated with surgical resection of the aneurysm.

  11. A giant left atrial appendage aneurysm with a large pinball-like thrombus in a 2 year old

    OpenAIRE

    Simarjot Singh Sarin; Tripat Bindra; Gurpreet S Chhabra

    2012-01-01

    Congenital left atrial appendage aneurysm is very rare. We describe a giant left atrial appendage aneurysm with a pinball-like mobile thrombus in a 2-year-old child with cardioembolic stroke. Patient underwent successful surgical resection of the aneurysm.

  12. Origin of archosaurian integumentary appendages: the bristles of the wild turkey beard express feather-type beta keratins.

    Science.gov (United States)

    Sawyer, Roger H; Washington, Lynette D; Salvatore, Brian A; Glenn, Travis C; Knapp, Loren W

    2003-06-15

    The discovery that structurally unique "filamentous integumentary appendages" are associated with several different non-avian dinosaurs continues to stimulate the development of models to explain the evolutionary origin of feathers. Taking the phylogenetic relationships of the non-avian dinosaurs into consideration, some models propose that the "filamentous integumentary appendages" represent intermediate stages in the sequential evolution of feathers. Here we present observations on a unique integumentary structure, the bristle of the wild turkey beard, and suggest that this non-feather appendage provides another explanation for some of the "filamentous integumentary appendages." Unlike feathers, beard bristles grow continuously from finger-like outgrows of the integument lacking follicles. We find that these beard bristles, which show simple branching, are hollow, distally, and express the feather-type beta keratins. The significance of these observations to explanations for the evolution of archosaurian integumentary appendages is discussed.

  13. Silk fibroin porous scaffolds for nucleus pulposus tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Chao; Yang, Qiang [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhu, Meifeng [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Du, Lilong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Tianjin Medical University, Tianjin 300070 (China); Zhang, Jiamin [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China); Ma, Xinlong [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Xu, Baoshan, E-mail: xubaoshan99@126.com [Department of Spine Surgery, Tianjin Hospital, Tianjin 300211 (China); Wang, Lianyong, E-mail: wly@nankai.edu.cn [The Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2014-04-01

    Intervertebral discs (IVDs) are structurally complex tissue that hold the vertebrae together and provide mobility to spine. The nucleus pulposus (NP) degeneration often results in degenerative IVD disease that is one of the most common causes of back and neck pain. Tissue engineered nucleus pulposus offers an alternative approach to regain the function of the degenerative IVD. The aim of this study is to determine the feasibility of porous silk fibroin (SF) scaffolds fabricated by paraffin-sphere-leaching methods with freeze-drying in the application of nucleus pulposus regeneration. The prepared scaffold possessed high porosity of 92.38 ± 5.12% and pore size of 165.00 ± 8.25 μm as well as high pore interconnectivity and appropriate mechanical properties. Rabbit NP cells were seeded and cultured on the SF scaffolds. Scanning electron microscopy, histology, biochemical assays and mechanical tests revealed that the porous scaffolds could provide an appropriate microstructure and environment to support adhesion, proliferation and infiltration of NP cells in vitro as well as the generation of extracellular matrix. The NP cell–scaffold construction could be preliminarily formed after subcutaneously implanted in a nude mice model. In conclusion, The SF porous scaffold offers a potential candidate for tissue engineered NP tissue. - Highlights: • Paraffin microsphere-leaching method is used to fabricate silk fibroin scaffold. • The scaffold has appropriate mechanical property, porosity and pore size • The scaffold supports growth and infiltration of nucleus pulposus cells. • Nucleus pulposus cells can secrete extracellular matrix in the scaffolds. • The scaffold is a potential candidate for tissue engineered nucleus pulposus.

  14. Anisotropic Porous Biodegradable Scaffolds for Musculoskeletal Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Eric L. W. de Mulder

    2009-10-01

    Full Text Available It has been generally accepted that tissue engineered constructs should closely resemble the in-vivo mechanical and structural properties of the tissues they are intended to replace. However, most scaffolds produced so far were isotropic porous scaffolds with non-characterized mechanical properties, different from those of the native healthy tissue. Tissues that are formed into these scaffolds are initially formed in the isotropic porous structure and since most tissues have significant anisotropic extracellular matrix components and concomitant mechanical properties, the formed tissues have no structural and functional relationships with the native tissues. The complete regeneration of tissues requires a second differentiation step after resorption of the isotropic scaffold. It is doubtful if the required plasticity for this remains present in already final differentiated tissue. It would be much more efficacious if the newly formed tissues in the scaffold could differentiate directly into the anisotropic organization of the native tissues. Therefore, anisotropic scaffolds that enable such a direct differentiation might be extremely helpful to realize this goal. Up to now, anisotropic scaffolds have been fabricated using modified conventional techniques, solid free-form fabrication techniques, and a few alternative methods. In this review we present the current status and discuss the procedures that are currently being used for anisotropic scaffold fabrication.

  15. Passive control of a falling sphere by elliptic-shaped appendages

    CERN Document Server

    Lācis, Uǧis; Mazzino, Andrea; Bagheri, Shervin

    2016-01-01

    The majority of investigations characterizing the motion of single or multiple particles in fluid flows consider canonical body shapes, such as spheres, cylinders, discs, etc. However, protrusions on bodies -- being either as surface imperfections or appendages that serve a function -- are ubiquitous in both nature and applications. In this work, we characterize how the dynamics of a sphere with an axis-symmetric wake is modified in the presence of thin three-dimensional elliptic-shaped protrusions. By investigating a wide range of three-dimensional appendages with different aspect ratios and lengths, we clearly show that the sphere with an appendage may robustly undergo an inverted-pendulum-like (IPL) instability. This means that the position of the appendage placed behind the sphere and aligned with the free-stream direction is unstable, in a similar way that an inverted pendulum is unstable under gravity. Due to this instability, non-trivial forces are generated on the body, leading to turn and drift, if t...

  16. Predictors of left atrial appendage stunning after electrical cardioversion of non-valvular atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    杨沙宁; 黄从新; 胡晓军; 金立军; 李凤翥; 彭水先

    2003-01-01

    Objective To identify predictors of left atrial appendage stunning after the use of electrical cardioversion to restore sinus rhythm in patients with non-valvular atrial fibrillation.Methods A total of 68 consecutive patients (45 men, 23 women, 60.5±8.7 years of age) with non-valvular atrial fibrillation undergoing electrical cardioversion were enlisted in this study. Clinical and echocardiographic variables were analyzed by univariate regression and multivariate logistic regression to investigate the relationship between occurrences of left atrial appendage stunning and these factors. Results Univariate analysis revealed that, in comparing patients without and with left atrial appendage stunning, there were significant differences in the duration of atrial fibrillation > 8 weeks (32.3% vs 75.5%, P 50 mm (29.0% vs 54.1%, P 8 weeks (OR=7.249, 95%CI=1.998-26.304, P 50 mm (OR=3.896, 95%CI=1.105-13.734, P8 weeks, left atrial diameter >50 mm, left ventricular ejection fraction <50%, and cumulative energy of electrical cardioversion are independent predictors of left atrial appendage stunning. Anticoagulation treatment should be individualized for patients undergoing electrical cardioversion to reduce the risk of both cardioversion-related thromboembolic events and hemorrhagic complications caused by warfarin treatment.

  17. Space robots with flexible appendages: Dynamic modeling, coupling measurement, and vibration suppression

    Science.gov (United States)

    Meng, Deshan; Wang, Xueqian; Xu, Wenfu; Liang, Bin

    2017-05-01

    For a space robot with flexible appendages, vibrations of flexible structure can be easily excited during both orbit and/or attitude maneuvers of the base and the operation of the manipulators. Hence, the pose (position and attitude) of the manipulator's end-effector will greatly deviate from the desired values, and furthermore, the motion of the manipulator will trigger and exacerbate vibrations of flexible appendages. Given lack of the atmospheric damping in orbit, the vibrations will last for quite a while and cause the on-orbital tasks to fail. We derived the rigid-flexible coupling dynamics of a space robot system with flexible appendages and established a coupling model between the flexible base and the space manipulator. A specific index was defined to measure the coupling degree between the flexible motion of the appendages and the rigid motion of the end-effector. Then, we analyzed the dynamic coupling for different conditions, such as modal displacements, joint angles (manipulator configuration), and mass properties. Moreover, the coupling map was adopted and drawn to represent the coupling motion. Based on this map, a trajectory planning method was addressed to suppress structure vibration. Finally, simulation studies of typical cases were performed, which verified the proposed models and method. This work provides a theoretic basis for the system design, performance evaluation, trajectory planning, and control of such space robots.

  18. Hedgehog signaling patterns the outgrowth of unpaired skeletal appendages in zebrafish

    Directory of Open Access Journals (Sweden)

    Ahlberg Per

    2007-06-01

    Full Text Available Abstract Background Little is known about the control of the development of vertebrate unpaired appendages such as the caudal fin, one of the key morphological specializations of fishes. Recent analysis of lamprey and dogshark median fins suggests the co-option of some molecular mechanisms between paired and median in Chondrichthyes. However, the extent to which the molecular mechanisms patterning paired and median fins are shared remains unknown. Results Here we provide molecular description of the initial ontogeny of the median fins in zebrafish and present several independent lines of evidence that Sonic hedgehog signaling emanating from the embryonic midline is essential for establishment and outgrowth of the caudal fin primordium. However, gene expression analysis shows that the primordium of the adult caudal fin does not harbor a Sonic hedgehog-expressing domain equivalent to the Shh secreting zone of polarizing activity (ZPA of paired appendages. Conclusion Our results suggest that Hedgehog proteins can regulate skeletal appendage outgrowth independent of a ZPA and demonstrates an unexpected mechanism for mediating Shh signals in a median fin primordium. The median fins evolved before paired fins in early craniates, thus the patterning of the median fins may be an ancestral mechanism that controls the outgrowth of skeletogenic appendages in vertebrates.

  19. Knockdown of Parhyale Ultrabithorax recapitulates evolutionary changes in crustacean appendage morphology.

    Science.gov (United States)

    Liubicich, Danielle M; Serano, Julia M; Pavlopoulos, Anastasios; Kontarakis, Zacharias; Protas, Meredith E; Kwan, Elaine; Chatterjee, Sandip; Tran, Khoa D; Averof, Michalis; Patel, Nipam H

    2009-08-18

    Crustaceans possess remarkably diverse appendages, both between segments of a single individual as well as between species. Previous studies in a wide range of crustaceans have demonstrated a correlation between the anterior expression boundary of the homeotic (Hox) gene Ultrabithorax (Ubx) and the location and number of specialized thoracic feeding appendages, called maxillipeds. Given that Hox genes regulate regional identity in organisms as diverse as mice and flies, these observations in crustaceans led to the hypothesis that Ubx expression regulates the number of maxillipeds and that evolutionary changes in Ubx expression have generated various aspects of crustacean appendage diversity. Specifically, evolutionary changes in the expression boundary of Ubx have resulted in crustacean species with either 0, 1, 2, or 3 pairs of thoracic maxillipeds. Here we test this hypothesis by altering the expression of Ubx in Parhyale hawaiensis, a crustacean that normally possesses a single pair of maxillipeds. By reducing Ubx expression, we can generate Parhyale with additional maxillipeds in a pattern reminiscent of that seen in other crustacean species, and these morphological alterations are maintained as the animals molt and mature. These results provide critical evidence supporting the proposition that changes in Ubx expression have played a role in generating crustacean appendage diversity and lend general insights into the mechanisms of morphological evolution.

  20. Air-flow sensitive hairs: boundary layers in oscillatory flows around arthropod appendages

    NARCIS (Netherlands)

    Steinmann, T.; Casas, J.; Krijnen, Gijsbertus J.M.; Dangles, O.

    2006-01-01

    The aim of this work is to characterize the boundary layer over small appendages in insects in longitudinal and transverse oscillatory flows. The problem of immediate interest is the early warning system in crickets perceiving flying predators using air-flow-sensitive hairs on cerci, two long

  1. Closure of Left Atrial Appendage With Persistent Distal Thrombus Using an Amplatzer Amulet Occluder.

    Science.gov (United States)

    Lange, Mathias; Bültel, Helmut; Weglage, Heinrich; Löffeld, Patrick; Wichter, Thomas

    2016-09-01

    A 73-year-old patient with permanent atrial fibrillation presented for left atrial appendage (LAA) occlusion. Transesophageal echocardiography demonstrated a thrombus in the distal LAA. This image series illustrates a "no touch" technique that was used to ensure successful implantation of an Amplatzer Amulet LAA occlusion device without the use of an embolization protection system.

  2. Thrombus-in-Transit Entrapped in a Partially Ligated Left Atrial Appendage

    Directory of Open Access Journals (Sweden)

    Farideh Roshanali

    2015-10-01

    Full Text Available A 54-year-old man referred to our center with Barlow’s disease and severe mitral regurgitation. He had atrial fibrillation (AF rhythm, with a mildly enlarged left atrium (LA. Transesophageal echocardiography (TEE showed no clot in the LA and LA appendage; there was only mild spontaneous echo contrast in the LA appendage. The patient underwent mitral valve repair and the Maze operation, during which the LA appendage was ligated with the double suture technique. He was discharged from the hospital in good condition and in sinus rhythm. He was recommended Warfarin and PT control.One month later, he returned with the complaint of vision loss twice in the left eye each time for a few seconds. The AF rhythm had returned.TEE demonstrated a fresh and mobile thrombus entrapped in the LA appendage with a small portion in the LA (Figures 1 and 2. Laboratory tests showed therapeutic international normalized ratio (INR. The patient refused re- operation.  Plavix was added to his medication, and he was discharged.

  3. Air-flow sensitive hairs: boundary layers in oscillatory flows around arthropod appendages

    NARCIS (Netherlands)

    Steinmann, T.; Casas, J.; Krijnen, G.J.M.; Dangles, O.

    2006-01-01

    The aim of this work is to characterize the boundary layer over small appendages in insects in longitudinal and transverse oscillatory flows. The problem of immediate interest is the early warning system in crickets perceiving flying predators using air-flow-sensitive hairs on cerci, two long append

  4. Epibulbar lipodermoids, preauricular appendages and polythelia in four generations: a new hereditary syndrome?

    DEFF Research Database (Denmark)

    Goldschmidt, Ernst; Jacobsen, Nina

    2010-01-01

    A new syndrome with abnormalities along the first branchial arch and the milk list is described in a family of four affected generations. The characteristics of the syndrome are epibulbar lipodermoids, preauricular appendages and polythelia. The expressivity varies but all affected have supernume...

  5. Developing an ancient epithelial appendage: FGF signalling regulates early tail denticle formation in sharks.

    Science.gov (United States)

    Cooper, Rory L; Martin, Kyle J; Rasch, Liam J; Fraser, Gareth J

    2017-01-01

    Vertebrate epithelial appendages constitute a diverse group of organs that includes integumentary structures such as reptilian scales, avian feathers and mammalian hair. Recent studies have provided new evidence for the homology of integumentary organ development throughout amniotes, despite their disparate final morphologies. These structures develop from conserved molecular signalling centres, known as epithelial placodes. It is not yet certain whether this homology extends beyond the integumentary organs of amniotes, as there is a lack of knowledge regarding their development in basal vertebrates. As the ancient sister lineage of bony vertebrates, extant chondrichthyans are well suited to testing the phylogenetic depth of this homology. Elasmobranchs (sharks, skates and rays) possess hard, mineralised epithelial appendages called odontodes, which include teeth and dermal denticles (placoid scales). Odontodes constitute some of the oldest known vertebrate integumentary appendages, predating the origin of gnathostomes. Here, we used an emerging model shark (Scyliorhinus canicula) to test the hypothesis that denticles are homologous to other placode-derived amniote integumentary organs. To examine the conservation of putative gene regulatory network (GRN) member function, we undertook small molecule inhibition of fibroblast growth factor (FGF) signalling during caudal denticle formation. We show that during early caudal denticle morphogenesis, the shark expresses homologues of conserved developmental gene families, known to comprise a core GRN for early placode morphogenesis in amniotes. This includes conserved expression of FGFs, sonic hedgehog (shh) and bone morphogenetic protein 4 (bmp4). Additionally, we reveal that denticle placodes possess columnar epithelial cells with a reduced rate of proliferation, a conserved characteristic of amniote skin appendage development. Small molecule inhibition of FGF signalling revealed placode development is FGF dependent

  6. Sustained safety and performance of the second-generation drug-eluting absorbable metal scaffold in patients with de novo coronary lesions: 12-month clinical results and angiographic findings of the BIOSOLVE-II first-in-man trial

    NARCIS (Netherlands)

    Haude, Michael; Ince, Hüseyin; Abizaid, Alexandre; Toelg, Ralph; Lemos, Pedro Alves; von Birgelen, Clemens; Christiansen, Evald Høj; Wijns, William; Neumann, Franz-Josef; Kaiser, Christoph; Eeckhout, Eric; Lim, Soo Teik; Escaned, Javier; Onuma, Yoshinobu; Garcia-Garcia, Hector M.; Waksman, Ron

    2016-01-01

    Aims Metal absorbable scaffolds constitute a conceptually attractive alternative to polymeric scaffolds. Promising 6-month outcomes of a second-generation drug-eluting absorbable metal scaffold (DREAMS 2G), consisting of an absorbable magnesium scaffold backbone, have been reported. We assessed the

  7. PLGA Microspheres Incorporated Gelatin Scaffold: Microspheres Modulate Scaffold Properties

    OpenAIRE

    Indranil Banerjee; Debasish Mishra; Maiti, Tapas K.

    2009-01-01

    Freeze drying is one of the popular methods of fabrication for poly(lactide-co-glycolide) (PLGA) microspheres incorporated polymer scaffolds. However, the consequence of microspheres incorporation on physical and biological properties of scaffold has not been studied yet. In this study, attempt has been made to characterize the effect of PLGA microsphere incorporation on the physical properties of freeze-dried gelatin scaffold and its influence on cytocompatibility. Scaffolds loaded with va...

  8. Acellular organ scaffolds for tumor tissue engineering

    Science.gov (United States)

    Guller, Anna; Trusova, Inna; Petersen, Elena; Shekhter, Anatoly; Kurkov, Alexander; Qian, Yi; Zvyagin, Andrei

    2015-12-01

    Rationale: Tissue engineering (TE) is an emerging alternative approach to create models of human malignant tumors for experimental oncology, personalized medicine and drug discovery studies. Being the bottom-up strategy, TE provides an opportunity to control and explore the role of every component of the model system, including cellular populations, supportive scaffolds and signalling molecules. Objectives: As an initial step to create a new ex vivo TE model of cancer, we optimized protocols to obtain organ-specific acellular matrices and evaluated their potential as TE scaffolds for culture of normal and tumor cells. Methods and results: Effective decellularization of animals' kidneys, ureter, lungs, heart, and liver has been achieved by detergent-based processing. The obtained scaffolds demonstrated biocompatibility and growthsupporting potential in combination with normal (Vero, MDCK) and tumor cell lines (C26, B16). Acellular scaffolds and TE constructs have been characterized and compared with morphological methods. Conclusions: The proposed methodology allows creation of sustainable 3D tumor TE constructs to explore the role of organ-specific cell-matrix interaction in tumorigenesis.

  9. Semiotic scaffolding of multicellularity

    DEFF Research Database (Denmark)

    Hoffmeyer, Jesper

    2015-01-01

    semiotic scaffoldings had to be invented in order to prevent this. While a unicellular self may go on to live practically forever, the multicellular self most often must run through an individuation process ending in the death of the individual. Due to basic differences in cells of plants, fungi...... of fertilization and thereby the need for a whole new set of elaborate semiotic scaffoldings. Multicellularity also opened the door to the formation symbiotic relations where cells with different genomes might collaborate or at least coexist inside the same body. All in all multicellularity led to an enormous...... diversification both of morphology space and the space of sensomotoric elaborations. New means for scaffolding of this expansion and diversification of possible life forms into functional patterns called for a corresponding growth in the space of semiotic tools (chemical processes, heat, light, sound, volatile...

  10. Semiotic Scaffolding in Mathematics

    DEFF Research Database (Denmark)

    Johansen, Mikkel Willum; Misfeldt, Morten

    2015-01-01

    This paper investigates the notion of semiotic scaffolding in relation to mathematics by considering its influence on mathematical activities, and on the evolution of mathematics as a research field. We will do this by analyzing the role different representational forms play in mathematical...... cognition, and more broadly on mathematical activities. In the main part of the paper, we will present and analyze three different cases. For the first case, we investigate the semiotic scaffolding involved in pencil and paper multiplication. For the second case, we investigate how the development of new...... in both mathematical cognition and in the development of mathematics itself, but mathematical cognition cannot itself be reduced to the use of semiotic scaffolding....

  11. Formation of body appendages during caudal regeneration in Platynereis dumerilii: adaptation of conserved molecular toolsets

    Directory of Open Access Journals (Sweden)

    Jan Grimmel

    2016-04-01

    Full Text Available Abstract Background Platynereis and other polychaete annelids with homonomous segmentation are regarded to closely resemble ancestral forms of bilateria. The head region comprises the prostomium, the peristomium, a variable number of cephalized body segments and several appendages, like cirri, antennae and palps. The trunk of such polychaetes shows numerous, nearly identical segments. Each segment bears a parapodium with species-specific morphology on either side. The posterior end of the trunk features a segment proliferation zone and a terminal pygidium with the anus and anal cirri. The removal of a substantial part of the posterior trunk is by no means lethal. Cells at the site of injury dedifferentiate and proliferate forming a blastema to regenerate both the pygidium and the proliferation zone. The pygidium forms new anal cirri, and the proliferation zone generates new segments at a rapid pace. The formation of body appendages like the cirri and the segmental parapodia can thus be studied in the caudal regenerate of Platynereis within only a few days. Results The development of body appendages in Platynereis is regulated by a network of genes common to polychaetes but also shared by distant taxa. We isolated DNA sequences from P. dumerilii of five genes known to be involved in appendage formation within other groups: Meis/homothorax, Pbx1/extradenticle, Dlx/Distal-less, decapentaplegic and specific protein 1/buttonhead. Analyses of expression patterns during caudal regeneration by in situ hybridization reveal striking similarities related to expression in arthropods and vertebrates. All genes exhibit transient expression during differentiation and growth of segments. As was shown previously in other phyla Pdu-Meis/hth and Pdu-Pbx1/exd are co-expressed, although the expression is not limited to the proximal part of the parapodia. Pdu-Dll is prominent in parapodia but upregulated in the anal cirri. No direct dependence concerning Pdu-Dll and

  12. Left atrial appendage closure for prevention of death, stroke, and bleeding in patients with nonvalvular atrial fibrillation.

    Science.gov (United States)

    Gloekler, Steffen; Saw, Jacqueline; Koskinas, Konstantinos C; Kleinecke, Caroline; Jung, Werner; Nietlispach, Fabian; Meier, Bernhard

    2017-08-26

    Nonvalvular atrial fibrillation (AF) is the most frequent arrhythmia with a prevalence of 1%-2% in the general population. Its prevalence increases with age and its diagnosis benefits of improvement and simplification of technologies for its detection. Today, AF affects approximately 7% of individuals age>65years and 15%-20% of octogenarians. Due to stasis and activation of coagulation in a fibrillating atrium, patients are at increased risk of thromboembolism, in particular ischemic stroke, with an overall stroke risk of 5% per year. Since the left atrium itself is round and smooth-walled, thrombi typically do not form there, but almost exclusively in the left atrial appendage (LAA), a blind sac-like heterogeneous structure trabeculated by pectinate muscles. In the past five decades, oral anticoagulation (OAC) with vitamin K antagonists (VKA) has been the state-of-the art treatment to prevent stroke and systemic embolism from thrombi in AF. In the last decade, nonvitamin K dependant oral anticoagulants (NOAC) have been shown to be overall superior to VKA with respect to efficacy and safety in large trials and registries. Given the safety issues of indefinite OAC with either VKA or NOAC, it is plausible to consider left atrial appendage closure (LAAC) as an alternative strategy for prevention of all three catastrophes for patients with AF on anticoagulation: death, stroke or other systemic embolization, and bleeding. In the past years, LAAC has been compared to VKA in prospective randomized trials, yielding superior results regarding efficacy and non-inferiority regarding safety in the mid-term. Today, the decision to provide the most appropriate treatment for a patient with AF (OAC, NOAC, or LAAC) is complex and needs to be individualized. This review provides a comprehensive update on the current state of LAAC in the field of prevention of death, stroke and bleedings in patients suffering from nonvalvular AF. We describe the pathophysiology of the LAA with regard

  13. Ultrasonographic diagnosis of torsion of testicular appendages; Diagnostico por ecografia de la torsion de los apendices testiculares

    Energy Technology Data Exchange (ETDEWEB)

    Esparza, J.; Gonzalez, A.; Cordero, J. L. [Hospital Virgen del Camino. Pamplona (Spain)

    2000-07-01

    To determine the efficacy of ultrasound in boys presenting torsion of a testicular appendage. A series of 30 boys with acute scrotal pain due to torsion of a testicular appendage was studied. Nine patients underwent surgery. The clinical findings and course in the remaining 21 suggested the presence of this abnormality. All of them underwent conventional and color Doppler ultrasound using a 7.5 MHz transducer. In 15 boys, ultrasound images depicted the affected appendage as a mass between the epididymal head and the testicle. In 13 cases, only signs of a inflammatory reaction, with enlargement of the epididymal head and tunicas presenting hyperflow and hydrocele, mimicking acute epididymities. In two cases, the images were normal. There is no definitive, distinguishing ultrasound image corresponding to testicular appendage torsion. Therefore, this diagnostic technique should be accompanied by clinical assessment. (Author) 14 refs.

  14. Cephalic and appendage morphology of the Cambrian arthropod Sidneyia inexpectans Walcott, 1911

    DEFF Research Database (Denmark)

    Stein, Martin

    2013-01-01

    as an evidence for variability of head segment counts in Cambrian arthropods, and to falsify the hypothesis of a head with three postantennular segments in the euarthropod ground pattern. Restudy of a substantial amount of material of S. inexpectans shows that previous interpretations of a short head were based...... understood, but the exopod seemed to differ from that of other artiopodans, except for the shared presence of lamellae. The head was considered to comprise only the ocular and antennular segments, these being covered entirely on the ventral side by a large doublure. This short head was often taken...... postantennular appendage bearing segments. The appendage morphology is shown to be consistent with artiopodan affinities. The exopod is of the bilobate flap-like type with lamellae inserting on the proximal portion, earlier proposed as a potential autapomorphy of Artiopoda. Reinforcement of artiopodan affinities...

  15. emc has a role in dorsal appendage fate formation in Drosophila oogenesis.

    Science.gov (United States)

    Papadia, Sofia; Tzolovsky, George; Zhao, Debiao; Leaper, Kevin; Clyde, Dorothy; Taylor, Paul; Asscher, Eva; Kirk, Graeme; Bownes, Mary

    2005-09-01

    extramacrochaetae (emc) functions during many developmental processes in Drosophila, such as sensory organ formation, sex determination, wing vein differentiation, regulation of eye photoreceptor differentiation, cell proliferation and development of the Malpighian tubules, trachea and muscles in the embryo. It encodes a Helix-Loop-Helix transcription factor that negatively regulates bHLH proteins. We show here that emc mRNA and protein are present throughout oogenesis in a dynamic expression pattern and that emc is involved in the regulation of chorionic appendage formation during late oogenesis. Expression of sense and antisense emc constructs as well as emc follicle cell clones leads to eggs with shorter, thicker dorsal appendages that are closer together at base than in the wild type. We demonstrate that emc lies downstream of fs(1)K10, gurken and EGFR in the Grk/EGFR signalling pathway and that it participates in controlling Broad-Complex expression at late stages of oogenesis.

  16. The integumental appendages of the turtle shell: an evo-devo perspective.

    Science.gov (United States)

    Moustakas-Verho, Jacqueline E; Cherepanov, Gennadii O

    2015-05-01

    The turtle shell is composed of dorsal armor (carapace) and ventral armor (plastron) covered by a keratinized epithelium. There are two epithelial appendages of the turtle shell: scutes (large epidermal shields separated by furrows and forming a unique mosaic) and tubercles (numerous small epidermal bumps located on the carapaces of some species). In our perspective, we take a synthetic, comparative approach to consider the homology and evolution of these integumental appendages. Scutes have been more intensively studied, as they are autapomorphic for turtles and can be diagnostic taxonomically. Their pattern of tessellation is stable phylogenetically, but labile in the individual. We discuss the history of developmental investigations of these structures and hypotheses of evolutionary and anomalous variation. In our estimation, the scutes of the turtle shell are an evolutionary novelty, whereas the tubercles found on the shells of some turtles are homologous to reptilian scales. © 2015 Wiley Periodicals, Inc.

  17. MARCKS-like protein is an initiating molecule in axolotl appendage regeneration.

    Science.gov (United States)

    Sugiura, Takuji; Wang, Heng; Barsacchi, Rico; Simon, Andras; Tanaka, Elly M

    2016-03-10

    Identifying key molecules that launch regeneration has been a long-sought goal. Multiple regenerative animals show an initial wound-associated proliferative response that transits into sustained proliferation if a considerable portion of the body part has been removed. In the axolotl, appendage amputation initiates a round of wound-associated cell cycle induction followed by continued proliferation that is dependent on nerve-derived signals. A wound-associated molecule that triggers the initial proliferative response to launch regeneration has remained obscure. Here, using an expression cloning strategy followed by in vivo gain- and loss-of-function assays, we identified axolotl MARCKS-like protein (MLP) as an extracellularly released factor that induces the initial cell cycle response during axolotl appendage regeneration. The identification of a regeneration-initiating molecule opens the possibility of understanding how to elicit regeneration in other animals.

  18. Epiploic appendagitis of caecum: a diagnostic dilemma [Appendicitis epiploica des Blinddarms: ein diagnostisches Dilemma

    Directory of Open Access Journals (Sweden)

    Rashid, Arshad

    2012-10-01

    Full Text Available [english] Epiploic appendagitis is a rare cause of acute abdomen. Depending on the site of occurrence, it can mimic any cause of acute abdomen or disease of the colon and caecal appendix; making its preoperative diagnosis very difficult. We present here a case of a 7-year-old boy misdiagnosed preoperatively as acute appendicitis and later on, upon surgical exploration, found to have caecal appendagitis. The affected epiploic appendage was removed and the patient had an uneventful recovery. We also review the relevant literature and discuss the measures to overcome this diagnostic dilemma. General surgeons should be aware of this self-limiting disease and consider it as a differential diagnosis of acute abdomen.[german] Appendicitis epiploica oder epiploische Appendagitis ist eine seltene Ursache des akuten Abdomens. Je nach Ort des Auftretens kann sie jede Ursache für akuten Unterleibsschmerz oder Erkrankungen des Dickdarms und Appendix vermiformis imitieren, was ihre präoperative Diagnose sehr schwierig macht. Wir präsentieren hier den Fall eines alten Jungen, bei dem präoperativ akute Blinddarmentzündung diagnostiziert wurde. Beim chirurgischen Eingriff stellte sich dann eine Appendicitis epiploica des Blinddarms als Befund heraus. Der betroffene Appendix epiploica wurde entfernt und der Patient erholte sich ohne besondere Vorkommnisse. Wir geben auch eine Übersicht über die relevante Literatur und diskutieren die Maßnahmen, um dieses diagnostische Dilemma zu überwinden. Allgemeine Chirurgen sollten sich dieser selbstlimitierenden Krankheit bewusst sein und sie als eine Differentialdiagnose bei akutem Abdomen in Betracht ziehen.

  19. Pallister-Killian syndrome: additional manifestations of cleft palate and sacral appendage.

    OpenAIRE

    McLeod, D R; Wesselman, L R; Hoar, D I

    1991-01-01

    We report a case of Pallister-Killian syndrome in a 28 week gestation infant. In addition to the characteristic phenotype, this patient had a cleft palate, diaphragmatic hernia, sacral appendage, and imperforate anus. The lymphocyte karyotype showed 96% 46,XX/4% 47,XX+i (12p) and the fibroblast karyotype 47,XX,+marker (presumed i(12p]. Fibroblast cytogenetic studies should be considered in all cases of diaphragmatic hernia associated with other malformations.

  20. Left atrial appendage occlusion for stroke prevention in atrial fibrillation in Europe

    DEFF Research Database (Denmark)

    Lip, Gregory Y.H.; Dagres, Nikolaos; Proclemer, Alessandro;

    2013-01-01

    The purpose of this EP wire survey was to assess clinical practice in relation to the use of left atrial appendage occlusion (LAAO) devices for stroke prevention in atrial fibrillation (AF) among members of the European Heart Rhythm Association research network. The average number of performed LA...... are most often performed by interventional cardiologists. Experience varied widely, and this was reflected in the wide range of thromboembolic and procedural (tamponade, bleeding) complications reported by the respondents to this EP wire survey....

  1. MARCKS-Like Protein is an Initiating Molecule in Axolotl Appendage Regeneration

    OpenAIRE

    Sugiura, Takuji; Wang, Heng; Barsacchi, Rico; Simon, Andras; Tanaka, Elly M.

    2016-01-01

    Identifying key molecules that launch regeneration has been a long sought goal. Multiple regenerative animals show an initial wound-associated proliferative response that transits into sustained proliferation if a significant portion of the body part has been removed 1-3 . In the axolotl, appendage amputation initiates a round of wound-associated cell cycle induction followed by continued proliferation that is dependent on nerve-derived signals 4,5 . A wound-associated molecule that triggers ...

  2. Acute epiploic appendagitis: A rare cause of acute abdomen and a diagnostic dilemma

    Directory of Open Access Journals (Sweden)

    Afnan F Almuhanna

    2016-01-01

    Full Text Available Acute epiploic appendagitis is a relatively rare cause of lower abdominal pain that clinically mimics other acute abdomen conditions that require surgery such as acute diverticulitis or appendicitis. Here, we report a case of a 50-year-old lady who presented with an unusual lower abdominal pain. Awareness of such a clinical condition with its characteristic imaging findings is important to avoid costly hospitalization, unnecessary antibiotic courses, and the morbidity and mortality associated with surgical procedures.

  3. Functional similarity in appendage specification by the Ultrabithorax and abdominal-A Drosophila HOX genes.

    OpenAIRE

    Casares, F.; Calleja, M.; Sánchez-Herrero, E

    1996-01-01

    In Drosophila, the Ultrabithorax, abdominal-A and Abdominal-B HOX genes of the bithorax complex determine the identity of part of the thorax and the whole abdomen. Either the absence of these genes or their ectopic expression transform segments into the identity of different ones along the antero-posterior axis. Here we show that misexpression of Ultrabithorax, abdominal-A and, to some extent, Abdominal-B genes cause similar transformations in some of the fruitfly appendages: antennal tissue ...

  4. Fabrication of metallic biomedical scaffolds with the space holder method: A review

    NARCIS (Netherlands)

    Arifvianto, B.; Zhou, J.

    2014-01-01

    Bone tissue engineering has been increasingly studied as an alternative approach to bone defect reconstruction. In this approach, new bone cells are stimulated to grow and heal the defect with the aid of a scaffold that serves as a medium for bone cell formation and growth. Scaffolds made of metalli

  5. Scaffolding Reading Comprehension Skills

    Science.gov (United States)

    Salem, Ashraf Atta Mohamed Safein

    2017-01-01

    The current study investigates whether English language teachers use scaffolding strategies for developing their students' reading comprehension skills or just for assessing their comprehension. It also tries to demonstrate whether teachers are aware of these strategies or they use them as a matter of habit. A questionnaire as well as structured…

  6. Left atrial appendage closure devices for cardiovascular risk reduction in atrial fibrillation patients

    Directory of Open Access Journals (Sweden)

    Cruz-Gonzalez I

    2015-05-01

    Full Text Available Ignacio Cruz-Gonzalez,* Juan Carlos Rama-Merchan,* Javier Rodriguez-Collado, Javier Martin-Moreiras, Alejandro Diego-Nieto, Antonio Arribas-Jimenez, Pedro Luís SanchezDepartment of Cardiology, University Hospital of Cardiology and IBSAL, Salamanca, Spain *Ignacio Cruz-Gonzalez and Juan Carlos Rama-Merchan have contributed equally to this work and should be considered co-first authors Abstract: Atrial fibrillation (AF is the most common sustained arrhythmia in clinical practice. AF is associated with a 4–5-fold increased risk of stroke and systemic embolism. Oral anticoagulant is the first-line therapy for this purpose, but it has various limitations and is often contraindicated or underutilized. Autopsy and surgical data have suggested that 90% of atrial thrombi in nonvalvular AF patients originate from the left atrial appendage, leading to the development of percutaneous closure for thromboembolic prevention. This paper examines the current evidence on left atrial appendage closure devices for cardiovascular risk reduction in AF patients. Keywords: atrial fibrillation, left atrial appendage, stroke, oral anticoagulant, percutaneous closure, thromboembolic prevention

  7. Electron-beam computed tomography findings of left atrial appendage in patients with cardiogenic cerebral embolism

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Makiko; Takahashi, Satoshi; Yonezawa, Hisashi [Iwate Medical Univ., Morioka (Japan). School of Medicine

    2002-04-01

    We studied electron-beam computed tomography (EBCT) findings in the left atrial appendage of 72 patients with cerebral embolism [27 in the acute phase (<48 hours) and 45 in the chronic phase], 9 cases with nonvalvular atrial fibrillation (NVAF) but without stroke, and 13 controls. EBCT was performed in the early (during injection of contrast medium), late-1 (5 min after injection), and-2 (10 min after injection) phases. In the acute phase patients, 41% showed filling defect (FD) in the early phase alone (FDE), 15% showed FD until late phase-1 (FDL-1), and 15% showed FD until late phase-2 (FDL-2). The chronic phase patients showed FDE in 33% of cases, FDL-1 in 8% and FDL-2 11%. Only FDE was observed in 44% in NVAF cases without stroke. No FDs were observed in controls. Flow velocity in the appendage measured by transesophageal echocardiography was 23{+-}10 cm/sec in 21 FDE cases, 14{+-}3 cm/sec in 3 FDL-1 cases, 29{+-}23 cm/sec in 4 FDL-2 cases, significantly lower in comparison with 58{+-}25 cm/s in the 23 cases with no FD. FDL-1 and -2 suggested severe stasis or presence of thrombus in the appendage, which indicated high risk of embolism slower the movement of MES through the sample volume. (author)

  8. Advanced CFD simulations of turbulent flows around appendages in CANDU fuel bundles

    Energy Technology Data Exchange (ETDEWEB)

    Abbasian, F.; Hadaller, G.I.; Fortman, R.A., E-mail: fabbasian@sternlab.com [Stern Laboratories Inc., Hamilton, Ontario (Canada)

    2013-07-01

    Computational Fluid Dynamics (CFD) was used to simulate the coolant flow in a modified 37-element CANDU fuel bundle, in order to investigate the effects of the appendages on the flow field. First, a subchannel model was created to qualitatively analyze the capabilities of different turbulence models such as k.ε, Reynolds Normalization Group (RNG), Shear Stress Transport (SST) and Large Eddy Simulation (LES). Then, the turbulence model with the acceptable quality was used to investigate the effects of positioning appendages, normally used in CANDU 37-element Critical Heat Flux (CHF) experiments, on the flow field. It was concluded that the RNG and SST models both show improvements over the k.ε method by predicting cross flow rates closer to those predicted by the LES model. Also the turbulence effects in the k.ε model dissipate quickly downstream of the appendages, while in the RNG and SST models appear at longer distances similar to the LES model. The RNG method simulation time was relatively feasible and as a result was chosen for the bundle model simulations. In the bundle model simulations it was shown that the tunnel spacers and leaf springs, used to position the bundles inside the pressure tubes in the experiments, have no measureable dominant effects on the flow field. The flow disturbances are localized and disappear at relatively short streamwise distances. (author)

  9. Improbable appendages: Deer antler renewal as a unique case of mammalian regeneration.

    Science.gov (United States)

    Kierdorf, Uwe; Li, Chunyi; Price, Joanna S

    2009-07-01

    Deer antlers are periodically replaced cranial appendages that develop from permanent outgrowths of the frontal bones known as pedicles. Antler re-growth is a unique regenerative event in mammals which in general are unable to replace bony appendages. Recent evidence suggests that antler regeneration is a stem cell-based process that depends on the activation of stem cells located in the pedicle periosteum which are presumed to be neural crest-derived. It has been demonstrated that several developmental pathways are involved in antler regeneration that are also known to play a role in the control of skeletal development and regeneration in other vertebrates. However, in contrast to most other natural examples of regeneration of complete body structures, antler regeneration apparently neither depends on a functional nerve supply nor involves a direct contact between wound epithelium and mesenchymal tissue. Antlers thus demonstrate that regeneration of a large bony appendage in a mammal can be achieved by a process that differs in certain aspects from epimorphic regeneration in lower vertebrates.

  10. Regulatory evolution of Tbx5 and the origin of paired appendages.

    Science.gov (United States)

    Adachi, Noritaka; Robinson, Molly; Goolsbee, Aden; Shubin, Neil H

    2016-09-01

    The diversification of paired appendages has been a major factor in the evolutionary radiation of vertebrates. Despite its importance, an understanding of the origin of paired appendages has remained elusive. To address this problem, we focused on T-box transcription factor 5 (Tbx5), a gene indispensable for pectoral appendage initiation and development. Comparison of gene expression in jawless and jawed vertebrates reveals that the Tbx5 expression in jawed vertebrates is derived in having an expression domain that extends caudal to the heart and gills. Chromatin profiling, phylogenetic footprinting, and functional assays enabled the identification of a Tbx5 fin enhancer associated with this apomorphic pattern of expression. Comparative functional analysis of reporter constructs reveals that this enhancer activity is evolutionarily conserved among jawed vertebrates and is able to rescue the finless phenotype of tbx5a mutant zebrafish. Taking paleontological evidence of early vertebrates into account, our results suggest that the gain of apomorphic patterns of Tbx5 expression and regulation likely contributed to the morphological transition from a finless to finned condition at the base of the vertebrate lineage.

  11. Cellulose and collagen derived micro-nano structured scaffolds for bone tissue engineering.

    Science.gov (United States)

    Aravamudhan, Aja; Ramos, Daisy M; Nip, Jonathan; Harmon, Matthew D; James, Roshan; Deng, Meng; Laurencin, Cato T; Yu, Xiaojun; Kumbar, Sangamesh G

    2013-04-01

    Scaffold based bone tissue engineering (BTE) has made great progress in regenerating lost bone tissue. Materials of natural and synthetic origin have been used for scaffold fabrication. Scaffolds derived from natural polymers offer greater bioactivity and biocompatibility with mammalian tissues to favor tissue healing, due to their similarity to native extracellular matrix (ECM) components. Often it is a challenge to fabricate natural polymer based scaffolds for BTE applications without compromising their bioactivity, while maintaining adequate mechanical properties. In this work, we report the fabrication and characterization of cellulose and collagen based micro-nano structured scaffolds using human osteoblasts (HOB) for BTE applications. These porous micro-nano structured scaffolds (average pore diameter 190 +/- 10 microm) exhibited mechanical properties in the mid range of human trabecular bone (compressive modulus 266.75 +/- 33.22 MPa and strength 12.15 3 +/- 2.23 MPa). These scaffolds supported the greater adhesion and phenotype maintenance of cultured HOB as reflected by higher levels of osteogenic enzyme alkaline phosphatase and mineral deposition compared to control polyester micro-nano structured scaffolds of identical pore properties. These natural polymer based micro-nano structured scaffolds may serve as alternatives to polyester based scaffolds for BTE applications.

  12. Scaffolding students’ assignments

    DEFF Research Database (Denmark)

    Slot, Marie Falkesgaard

    2013-01-01

    This article discusses scaffolding in typical student assignments in mother tongue learning materials in upper secondary education in Denmark and the United Kingdom. It has been determined that assignments do not have sufficient scaffolding end features to help pupils understand concepts and build...... objects. The article presents the results of empirical research on tasks given in Danish and British learning materials. This work is based on a further development of my PhD thesis: “Learning materials in the subject of Danish” (Slot 2010). The main focus is how cognitive models (and subsidiary explicit...... learning goals) can help students structure their argumentative and communica-tive learning processes, and how various multimodal representations can give more open-ended learning possibilities for collaboration. The article presents a short introduction of the skills for 21st century learning and defines...

  13. Intra-procedural imaging of the left atrial appendage: implications for closure with the Amplatzer™ cardiac plug.

    Science.gov (United States)

    Sobrino, Ayax; Tzikas, Apostolos; Freixa, Xavier; Pulido, Alicia; Chan, Jason; Garceau, Patrick; Ibrahim, Reda; Basmadjian, Arsène J

    2014-01-01

    To evaluate intra-procedural imaging with transesophageal echocardiography and angiography during left atrial appendage occlusion using the Amplatzer™ Cardiac Plug with regard to sizing and final device shape. Left atrial appendage ostium dimensions and diameter at a depth of 10mm from the ostium were measured by transesophageal echocardiography (0-180°) and angiography (RAO 30° - Cranial 20°) in consecutive patients undergoing left atrial appendage occlusion using the ACP with an oversizing strategy of 10-20% relative to the baseline measurements. After delivery, ACP dimensions were measured and device shape was assessed. Twenty-seven consecutive patients underwent successful uncomplicated left atrial appendage closure with Amplatzer™ Cardiac Plug. We found a significant difference between the largest and smallest left atrial appendage diameter measured with transesophageal echocardiography (22.3±4.2 vs. 18.1±4.1mm, p<0.001). By the end of the procedure (by angiography), ACP had an optimal shape in 17 patients (63%), a strawberry-like shape in 7 patients (26%), and a square-like shape in 3 patients (11%). ACP was oversized on average by 1.5±2.7 and 3.3±2.3mm compared to transesophageal echocardiography and angiography, respectively. The final shape of the device was not significantly associated with the degree of oversizing. We found a considerable variability in the assessment of the left atrial appendage, using transesophageal echocardiography and angiography. The degree of Amplatzer™ Cardiac Plug expansion within the left atrial appendage and the final shape of the device were not associated with the degree of oversizing. Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.

  14. Bacterial surface appendages strongly impact nanomechanical and electrokinetic properties of Escherichia coli cells subjected to osmotic stress.

    Directory of Open Access Journals (Sweden)

    Grégory Francius

    Full Text Available The physicochemical properties and dynamics of bacterial envelope, play a major role in bacterial activity. In this study, the morphological, nanomechanical and electrohydrodynamic properties of Escherichia coli K-12 mutant cells were thoroughly investigated as a function of bulk medium ionic strength using atomic force microscopy (AFM and electrokinetics (electrophoresis. Bacteria were differing according to genetic alterations controlling the production of different surface appendages (short and rigid Ag43 adhesins, longer and more flexible type 1 fimbriae and F pilus. From the analysis of the spatially resolved force curves, it is shown that cells elasticity and turgor pressure are not only depending on bulk salt concentration but also on the presence/absence and nature of surface appendage. In 1 mM KNO(3, cells without appendages or cells surrounded by Ag43 exhibit large Young moduli and turgor pressures (∼700-900 kPa and ∼100-300 kPa respectively. Under similar ionic strength condition, a dramatic ∼50% to ∼70% decrease of these nanomechanical parameters was evidenced for cells with appendages. Qualitatively, such dependence of nanomechanical behavior on surface organization remains when increasing medium salt content to 100 mM, even though, quantitatively, differences are marked to a much smaller extent. Additionally, for a given surface appendage, the magnitude of the nanomechanical parameters decreases significantly when increasing bulk salt concentration. This effect is ascribed to a bacterial exoosmotic water loss resulting in a combined contraction of bacterial cytoplasm together with an electrostatically-driven shrinkage of the surface appendages. The former process is demonstrated upon AFM analysis, while the latter, inaccessible upon AFM imaging, is inferred from electrophoretic data interpreted according to advanced soft particle electrokinetic theory. Altogether, AFM and electrokinetic results clearly demonstrate the

  15. Scaffold: Quantum Programming Language

    Science.gov (United States)

    2012-07-24

    included popular classical high-level imperative programming languages (C/C++, Java) [16, 25, 11], hardware description languages ( Verilog ) [13], C-to...hardware languages (System-C) [14] and existing quantum programming languages (QCL) [23]. • Variant of C and Verilog : Scaffold syntax was chosen to be...very similar to C (and to some extent Verilog HDL.) This reflects our belief that expressing computations in terms of familiar iterative and imperative

  16. Novel Scaffold FingerPrint (SFP): applications in scaffold hopping and scaffold-based selection of diverse compounds.

    Science.gov (United States)

    Rabal, Obdulia; Amr, Fares Ibrahim; Oyarzabal, Julen

    2015-01-26

    A novel 2D Scaffold FingerPrint (SFP) for mining ring fragments is presented. The rings are described not only by their topology, shape, and pharmacophoric features (hydrogen-bond acceptors and donors, their relative locations, sp3 carbons, and chirality) but also by the position and nature of their growing vectors because they play a critical role from the drug discovery perspective. SFP can be used (i) to identify alternative chemotypes to a reference ring either in a visual mode or by running quantitative similarity searches and (ii) in chemotype-based diversity selections. Two retrospective case studies focused on melanin concentrating hormone 1-receptor antagonists (MCH-R1) and phosphodiesterase-5 inhibitors (PDE5) demonstrate the capability of this method for identifying novel structurally different and synthetically accessible chemotypes. Good enrichment factor (155 and 219) and recall values (46% and 73%) are found within the first 100 ranked hits (0.3% of screened database). Our 2D SFP descriptor outperforms well-validated current gold-standard 2D fingerprints (ECFP_6) and 3D approaches based on shape and electrostatic similarity. Scaffold-based selection of diverse compounds has a critical impact on corporate library design and compound acquisitions; thus, a novel strategy is introduced that uses diverse scaffold selections using this SFP descriptor combined with R-group selection at the different substitution sites. Both approaches are available as part of an interactive web-based application that requires minimal input and no computational knowledge by medicinal chemists.

  17. Plant-Derived Human Collagen Scaffolds for Skin Tissue Engineering

    Science.gov (United States)

    Willard, James J.; Drexler, Jason W.; Das, Amitava; Roy, Sashwati; Shilo, Shani; Shoseyov, Oded

    2013-01-01

    Tissue engineering scaffolds are commonly formed using proteins extracted from animal tissues, such as bovine hide. Risks associated with the use of these materials include hypersensitivity and pathogenic contamination. Human-derived proteins lower the risk of hypersensitivity, but possess the risk of disease transmission. Methods engineering recombinant human proteins using plant material provide an alternate source of these materials without the risk of disease transmission or concerns regarding variability. To investigate the utility of plant-derived human collagen (PDHC) in the development of engineered skin (ES), PDHC and bovine hide collagen were formed into tissue engineering scaffolds using electrospinning or freeze-drying. Both raw materials were easily formed into two common scaffold types, electrospun nonwoven scaffolds and lyophilized sponges, with similar architectures. The processing time, however, was significantly lower with PDHC. PDHC scaffolds supported primary human cell attachment and proliferation at an equivalent or higher level than the bovine material. Interleukin-1 beta production was significantly lower when activated THP-1 macrophages where exposed to PDHC electrospun scaffolds compared to bovine collagen. Both materials promoted proper maturation and differentiation of ES. These data suggest that PDHC may provide a novel source of raw material for tissue engineering with low risk of allergic response or disease transmission. PMID:23298216

  18. Engineering Pre-vascularized Scaffolds for Bone Regeneration.

    Science.gov (United States)

    Barabaschi, Giada D G; Manoharan, Vijayan; Li, Qing; Bertassoni, Luiz E

    2015-01-01

    Survival of functional tissue constructs of clinically relevant size depends on the formation of an organized and uniformly distributed network of blood vessels and capillaries. The lack of such vasculature leads to spatio-temporal gradients in oxygen, nutrients and accumulation of waste products inside engineered tissue constructs resulting in negative biological events at the core of the scaffold. Unavailability of a well-defined vasculature also results in ineffective integration of scaffolds to the host vasculature upon implantation. Arguably, one of the greatest challenges in engineering clinically relevant bone substitutes, therefore, has been the development of vascularized bone scaffolds. Various approaches ranging from peptide and growth factor functionalized biomaterials to hyper-porous scaffolds have been proposed to address this problem with reasonable success. An emerging alternative to address this challenge has been the fabrication of pre-vascularized scaffolds by taking advantage of biomanufacturing techniques, such as soft- and photo-lithography or 3D bioprinting, and cell-based approaches, where functional capillaries are engineered in cell-laden scaffolds prior to implantation. These strategies seek to engineer pre-vascularized tissues in vitro, allowing for improved anastomosis with the host vasculature upon implantation, while also improving cell viability and tissue development in vitro. This book chapter provides an overview of recent methods to engineer pre-vascularized scaffolds for bone regeneration. We first review the development of functional blood capillaries in bony structures and discuss controlled delivery of growth factors, co-culture systems, and on-chip studies to engineer vascularized cell-laden biomaterials. Lastly, we review recent studies using microfabrication techniques and 3D printing to engineer pre-vascularized scaffolds for bone tissue engineering.

  19. Privileged scaffolds in lead generation.

    Science.gov (United States)

    Zhao, Hongyu; Dietrich, Justin

    2015-07-01

    The term "privileged scaffold" was coined in 1988 and the strategy was to construct high-affinity ligands from core structures that can bind more than one receptor. Since then, the privileged scaffold-based design has evolved from a stand-alone technology to an integral component of various lead generation platforms. In this review, the authors discuss the applications of the privileged scaffold concept in current lead generation. Specifically, the authors cover the role that privileged scaffolds have played in the mass production of compounds to feed high-throughput screening (HTS) and its role in the design of ligands targeting protein-protein interactions, multiple ligands and warhead-based ligands. It is not the intention of the authors to review all privileged scaffolds known to date. Rather, the aim of this review is to highlight the strategic value of the concept of privileged scaffolds in various contemporary lead generation platforms. The privileged scaffolds as described by the original definition proved abundant in the available chemical space. HTS and other screening methods, in addition to greatly enhanced compound collections, make privileged scaffold-based design less relevant in finding high-affinity ligands than originally envisioned. However, the principle of privileged scaffolds has greatly enhanced and empowered current lead generation technologies.

  20. The cephalopod arm crown: appendage formation and differentiation in the Hawaiian bobtail squid Euprymna scolopes.

    Science.gov (United States)

    Nödl, Marie-Therese; Kerbl, Alexandra; Walzl, Manfred G; Müller, Gerd B; de Couet, Heinz Gert

    2016-01-01

    Cephalopods are a highly derived class of molluscs that adapted their body plan to a more active and predatory lifestyle. One intriguing adaptation is the modification of the ventral foot to form a bilaterally symmetric arm crown, which constitutes a true morphological novelty in evolution. In addition, this structure shows many diversifications within the class of cephalopods and therefore offers an interesting opportunity to study the molecular underpinnings of the emergence of phenotypic novelties and their diversification. Here we use the sepiolid Euprymna scolopes as a model to study the formation and differentiation of the decabrachian arm crown, which consists of four pairs of sessile arms and one pair of retractile tentacles. We provide a detailed description of arm crown formation in order to understand the basic morphology and the developmental dynamics of this structure. We show that the morphological formation of the cephalopod appendages occurs during distinct phases, including outgrowth, elongation, and tissue differentiation. Early outgrowth is characterized by uniform cell proliferation, while the elongation of the appendages initiates tissue differentiation. The latter progresses in a gradient from proximal to distal, whereas cell proliferation becomes restricted to the distal-most end of the arm. Differences in the formation of arms and tentacles exist, with the tentacles showing an expedite growth rate and higher complexity at younger stages. The early outgrowth and differentiation of the E. scolopes arm crown shows similarities to the related, yet derived cephalopod Octopus vulgaris. Parallels in the growth and differentiation of appendages seem to exist throughout the animal kingdom, raising the question of whether these similarities reflect a recruitment of similar molecular patterning pathways.

  1. Percutaneous closure of a very large left atrial appendage using the Amplatzer amulet.

    Science.gov (United States)

    Freixa, Xavier; Kwai Chan, Jason Leung; Tzikas, Apostolos; Garceau, Patrick; Basmadjian, Arsène; Ibrahim, Réda

    2013-10-01

    Although percutaneous left atrial appendage (LAA) closure is becoming a common procedure worldwide, there are still some anatomic limitations. The size of the LAA is one of the current limitations as the most popular devices do not allow the closure of very large LAAs. The new Amplatzer Cardiac Plug 2, also called "Amulet," has been redesigned not only to improve delivery and safety but also to allow the closure of larger LAAs. The present report describes the successful closure of a very large LAA using the Amulet.

  2. Navx-guided Cryoablation of Atrial Tachycardia Inside the Left Atrial Appendage

    Science.gov (United States)

    Pandozi, Claudio; Galeazzi, Marco; Lavalle, Carlo; Ficili, Sabina; Russo, Maurizio; Santini, Massimo

    2010-01-01

    Radiofrequency ablation procedures inside the left atrial appendage (LAA) are likely to involve dangerous complications because of a high thrombogenic effect. Cryoablation procedures are supposed to be safer. We describe two cases of successful cryoablation procedures. Two NavX-guided cryoablations of permanent focal atrial arrhythmias arising from the LAA were performed. Left atrial reconstruction and mapping allowed the zone of the earliest atrial potential to be recorded; the entire course of the ablation catheter was monitored. The arrhythmias were successfully ablated; no thrombotic complications were observed. PMID:21346824

  3. Instruction, Cognitive Scaffolding, and Motivational Scaffolding in Writing Center Tutoring

    Science.gov (United States)

    Mackiewicz, Jo; Thompson, Isabelle

    2014-01-01

    In this study, we quantitatively analyze the discourse of experienced writing center tutors in 10 highly satisfactory conferences. Specifically, we analyze tutors' instruction, cognitive scaffolding, and motivational scaffolding, all tutoring strategies identified in prior research from other disciplines as educationally effective. We find that…

  4. Single trans-septal access technique for left atrial intracardiac echocardiography to guide left atrial appendage closure.

    Science.gov (United States)

    Aguirre, Daniel; Pincetti, Christian; Perez, Luis; Deck, Carlos; Alfaro, Mario; Vergara, Maria Jesus; Maluenda, Gabriel

    2017-08-24

    This registry aimed to describe the safety and feasibility of a single trans-septal (TS) access technique for left intracardiac echocardiography (ICE) guidance of left-atrial appendage (LAA) closure procedure. LAA closure is currently accepted as an alternative to oral anticoagulation (OAC) in patients with non-valvular atrial fibrillation (NVAF) who are at high-risk for bleeding. Currently, LAA closure procedure is typically performed under trans-esophageal echocardiogram (TEE) guidance. Although, ICE has the advantage of not requiring profound sedation/anesthesia, ICE-LAA imaging quality is often limited from the right atrium requiring double TS access. Twenty-two patients with NVAF underwent LAA closure using the Amplatzer Amulet™ device (St Jude Medical) under ICE guidance from the left atrium. The ICE AcuNav catheter (Biosense Webster) and the Amulet delivery sheath were advanced into the LA through single TS puncture technique. The population was predominately male (59.1%) with a mean age of 74 ± 9.3 years, at high-risk for stroke (mean CHADS2 score of 3.8 ± 1.1) and bleeding (mean HAS BLED score of 3.5 ± 1.3). The Amplatzer Amulet(TM) device was successfully implanted in all patients. No procedural related complications including device embolization were noted. No major cardiovascular events occurred and all patients were discharged alive. At 30-day follow-up all patients remained alive, free of ischemic stroke and with no residual leak or device thrombus on TEE. This initial experience suggests that LAA occlusion with the Amplatzer Amulet device using ICE guidance from the left atrium via a single trans-septal technique is feasible and safe. © 2017 Wiley Periodicals, Inc.

  5. Comparison of the Feasibility and Safety of First- versus Second-Generation AMPLATZER™ Occluders for Left Atrial Appendage Closure

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    Baravan Al-Kassou

    2017-01-01

    Full Text Available Introduction. Left atrial appendage closure (LAAC is considered an alternative to oral anticoagulation therapy in patients with atrial fibrillation (AF. The aim of this study was to compare the safety and efficacy of the first- and second-generation AMPLATZER Devices for LAAC, AMPLATZER Cardiac Plug (ACP versus AMPLATZER Amulet™. Methods. Procedural data, such as fluoroscopy time, radiation dose, and contrast-dye, as well as VARC criteria and major adverse events (MAEs were assessed for both devices. The rate of peridevice leaks was analyzed at echocardiographic follow-up. Results. A total of 196 patients with AF underwent LAAC with the ACP (n=99 or Amulet device (n=97. The use of Amulet was associated with significantly lower fluoroscopy time (14.8 ± 7.4 min versus 10.6 ± 4.1 min; p<0.001, lower radiation dose (4833 ± 3360 cGy⁎cm2 versus 3206 ± 2169 cGy⁎cm2; p<0.001, and reduced amount of contrast-dye (150.2 ± 83.9 ml versus 128.8 ± 46.0 ml; p=0.03. Furthermore, LAAC with Amulet devices resulted in lower device-resizing rates (3 versus 16 cases; p=0.001. Peridevice leaks were less frequent in the Amulet group (12 versus 4; p=0.03. MAE occurred in 6 ACP and 4 Amulet patients (p=0.58. Conclusions. The Amulet device is associated with shorter fluoroscopy times and radiation dosages, reduced use of contrast-dye, lower recapture rates, and less peridevice leaks as compared to the ACP.

  6. Novel antibacterial nanofibrous PLLA scaffolds.

    Science.gov (United States)

    Feng, Kai; Sun, Hongli; Bradley, Mark A; Dupler, Ellen J; Giannobile, William V; Ma, Peter X

    2010-09-15

    In order to achieve high local bioactivity and low systemic side effects of antibiotics in the treatment of dental, periodontal and bone infections, a localized and temporally controlled delivery system is crucial. In this study, a three-dimensional (3-D) porous tissue engineering scaffold was developed with the ability to release antibiotics in a controlled fashion for long-term inhibition of bacterial growth. The highly soluble antibiotic drug, doxycycline (DOXY), was successfully incorporated into PLGA nanospheres using a modified water-in-oil-in-oil (w/o/o) emulsion method. The PLGA nanospheres (NS) were then incorporated into prefabricated nanofibrous PLLA scaffolds with a well interconnected macro-porous structure. The release kinetics of DOXY from four different PLGA NS formulations on a PLLA scaffold was investigated. DOXY could be released from the NS-scaffolds in a locally and temporally controlled manner. The DOXY release is controlled by DOXY diffusion out of the NS and is strongly dependent upon the physical and chemical properties of the PLGA. While PLGA50-6.5K, PLGA50-64K, and PLGA75-113K NS-scaffolds discharge DOXY rapidly with a high initial burst release, PLGA85-142K NS-scaffold can extend the release of DOXY to longer than 6weeks with a low initial burst release. Compared to NS alone, the NS incorporated on a 3-D scaffold had significantly reduced the initial burst release. In vitro antibacterial tests of PLGA85 NS-scaffold demonstrated its ability to inhibit common bacterial growth (S. aureus and E. coli) for a prolonged duration. The successful incorporation of DOXY onto 3-D scaffolds and its controlled release from scaffolds extends the usage of nano-fibrous scaffolds from the delivery of large molecules such as growth factors to the delivery of small hydrophilic drugs, allowing for a broader application and a more complex tissue engineering strategy. 2010 Elsevier B.V. All rights reserved.

  7. Intracellular assembly of cyanophage Syn5 proceeds through a scaffold-containing procapsid.

    Science.gov (United States)

    Raytcheva, Desislava A; Haase-Pettingell, Cameron; Piret, Jacqueline M; King, Jonathan A

    2011-03-01

    Syn5 is a marine cyanophage that is propagated on the marine photosynthetic cyanobacterial strain Synechococcus sp. WH8109 under laboratory conditions. Cryoelectron images of this double-stranded DNA (dsDNA) phage reveal an icosahedral capsid with short tail appendages and a single novel hornlike structure at the vertex opposite the tail. Despite the major impact of cyanophages on life in the oceans, there is limited information on cyanophage intracellular assembly processes within their photosynthetic hosts. The one-step growth curve of Syn5 demonstrated a short cycle with an eclipse period of ∼45 min, a latent phase of ∼60 min, and a burst size of 20 to 30 particles per cell at 28°C. SDS-PAGE and Western blot analysis of cell lysates at different times after infection showed the synthesis of major virion proteins and their increase as the infection progressed. The scaffolding protein of Syn5, absent from virions, was identified in the lysates and expressed from the cloned gene. It migrated anomalously on SDS-PAGE, similar to the phage T7 scaffolding protein. Particles lacking DNA but containing the coat and scaffolding proteins were purified from Syn5-infected cells using CsCl centrifugation followed by sucrose gradient centrifugation. Electron microscopic images of the purified particles showed shells lacking condensed DNA but filled with protein density, presumably scaffolding protein. These findings suggest that the cyanophages form infectious virions through the initial assembly of scaffolding-containing procapsids, similar to the assembly pathways for the enteric dsDNA bacteriophages. Since cyanobacteria predate the enteric bacteria, this procapsid-mediated assembly pathway may have originated with the cyanophages.

  8. Bimodal Porous Scaffolds by Sequential Electrospinning of Poly(glycolic acid with Sucrose Particles

    Directory of Open Access Journals (Sweden)

    B. Wulkersdorfer

    2010-01-01

    Full Text Available Electrospinning is a method to produce fine, biopolymer mesh with a three-dimensional architecture that mimics native extra-cellular matrix. Due to the small fiber diameter created in this process, conventional electrospun scaffolds have pore sizes smaller than the diameter of most cells. These scaffolds have limited application in tissue engineering due to poor cell penetration. We developed a hybrid electrospinning/particulate leaching technique to create scaffolds with increased porosity and improved cellular ingrowth. Poly(glycolic acid (PGA and a sucrose-ethanol suspension were electrospun in equal, alternating sequences at intervals of one, two, and ten minutes each. The scaffolds revealed fiber mesh with micropores of 10 m and uniformly distributed sucrose particles. Particulate leaching of sucrose from the one- or two-minute scaffolds revealed honeycomb structures with interconnected macropores between 50 and 250 m. Sucrose leaching from the ten-minute scaffolds resulted in laminated structures with isolated macropores between 200 and 350 m. Macropore size was directly proportional to the duration of the sucrose spinning interval. After 24 hours of cell culture, conventionally spun scaffolds demonstrated no cellular penetration. Conversely, the PGA/sucrose scaffolds demonstrated deep cellular penetration. This hybrid technique represents a novel method of generating electrospun scaffolds with interconnected pores suitable for cellular ingrowth.

  9. Development of keratin-chitosan-gelatin composite scaffold for soft tissue engineering.

    Science.gov (United States)

    Kakkar, Prachi; Verma, Sudhanshu; Manjubala, I; Madhan, B

    2014-12-01

    Keratin has gained much attention in the recent past as a biomaterial for wound healing owing to its biocompatibility, biodegradability, intrinsic biological activity and presence of cellular binding motifs. In this paper, a novel biomimetic scaffold containing keratin, chitosan and gelatin was prepared by freeze drying method. The prepared keratin composite scaffold had good structural integrity. Fourier Transform Infrared (FTIR) spectroscopy showed the retention of the native structure of individual biopolymers (keratin, chitosan, and gelatin) used in the scaffold. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) results revealed a high thermal denaturation temperature of the scaffold (200-250°C). The keratin composite scaffold exhibited tensile strength (96 kPa), compression strength (8.5 kPa) and water uptake capacity (>1700%) comparable to that of a collagen scaffold, which was used as control. The morphology of the keratin composite scaffold observed using a Scanning Electron Microscope (SEM) exhibited good porosity and interconnectivity of pores. MTT assay using NIH 3T3 fibroblast cells demonstrated that the cell viability of the keratin composite scaffold was good. These observations suggest that the keratin-chitosan-gelatin composite scaffold is a promising alternative biomaterial for tissue engineering applications.

  10. Fabrication of highly porous biodegradable biomimetic nanocomposite as advanced bone tissue scaffold

    Directory of Open Access Journals (Sweden)

    Abdalla Abdal-hay

    2017-02-01

    Full Text Available Development of bioinspired or biomimetic materials is currently a challenge in the field of tissue regeneration. In-situ 3D biomimetic microporous nanocomposite scaffold has been developed using a simple lyophilization post hydrothermal reaction for bone healing applications. The fabricated 3D porous scaffold possesses advantages of good bonelike apatite particles distribution, thermal properties and high porous interconnected network structure. High dispersion bonelike apatite nanoparticles (NPs rapidly nucleated and deposited from surrounding biological minerals within chitosan (CTS matrices using hydrothermal technique. After that, freeze-drying method was applied on the composite solution to form the desired porous 3D architecture. Interestingly, the porosity and pore size of composite scaffold were not significantly affected by the particles size and particles content within the CTS matrix. Our results demonstrated that the compression modulus of porous composite scaffold is twice higher than that of plain CTS scaffold, indicating a maximization of the chemical interaction between polymer matrix and apatite NPs. Cytocompatibility test for MC3T3-E1 pre-osteoblasts cell line using MTT-indirect assay test showed that the fabricated 3D microporous nanocomposite scaffold possesses higher cell proliferation and growth than that of pure CTS scaffold. Collectively, our results suggest that the newly developed highly porous apatite/CTS nanocomposite scaffold as an alternative of hydroxyapatite/CTS scaffold may serve as an excellent porous 3D platform for bone tissue regeneration.

  11. Analytical method for the attitude stability of partially liquid filled spacecraft with flexible appendage

    Science.gov (United States)

    Yan, Yulong; Yue, Baozeng

    2017-02-01

    In this paper, the attitude stability of liquid-filled spacecraft with flexible appendage is investigated. The motion of liquid sloshing is modeled as the spherical pendulum, and the flexible appendage is approached by a linear shearing beam. Nonlinear dynamic equations of the coupled system are derived from the Hamiltonian. The stability of the coupled system was analyzed by using the energy-Casimir method, and the nonlinear stability theorem of the coupled spacecraft system was also obtained. Through numerical computation, the correctness of the proposed theorem is verified and the boundary curves of the stable region are presented. The increase of the angular velocity and flexible attachment length will weaken the attitude stability, and the change of the filled ratio of liquid fuel tank has a different influence on the stability of the coupled spacecraft, depending on the different conditions. The attitude stability analysis of the coupled spacecraft system in this context is useful for selecting appropriate parameters in the complex spacecraft design.

  12. Evaluation of body appendage injuries to juvenile signal crayfish (Pacifastacus leniusculus: relationships and consequences

    Directory of Open Access Journals (Sweden)

    Kouba A.

    2011-05-01

    Full Text Available Aggressive behaviour occurs frequently in crayfish and commonly results in injuries to body appendages. This study aimed to evaluate injuries to antennae, chelae, and walking legs of juvenile signal crayfish after seven months of rearing at high stocking density. We suggest that the high incidence of antennae injuries (66.8% is related to their delicate structure and exposed position, which makes them vulnerable to damage. Chelae were more frequently injured (45.5% than walking legs (7.8–23.6%. Considering the robustness of these structures and the scarcity of animals with both chelae missing and/or regenerating (4.9%, it seemed that injured animals were often killed by less injured ones. Antennae of crayfish with a single injured chela were more frequently injured on the side of the body with the damaged chela, and a similar pattern was observed for walking legs. Expanding on previous research reporting a negative relationship only between incidence of chela injury and crayfish size, we found this relationship to be significant for all evaluated appendages. We hypothesize that any injury and accompanying regeneration may have significant impact on subsequent injuries, overall growth, and reproductive success, and may result in death through cannibalism.

  13. Effect of Red Clover Isoflavones over Skin, Appendages, and Mucosal Status in Postmenopausal Women

    Directory of Open Access Journals (Sweden)

    Markus Lipovac

    2011-01-01

    Full Text Available Objective. Evaluate in postmenopausal women the effect of red clover extract (RCE isoflavones over subjective status of skin, appendages, and several mucosal sites. Method. Postmenopausal women (n=109 were randomly assigned to receive either two daily capsules of the active compound (80 mg RCE, Group A or placebo of equal appearance (Group B for a 90-day period. After a washout period of 7 days, medication was crossed over and taken for 90 days more. Subjective improvement of skin, appendages, and several mucosal site status was assessed for each studied group at 90 and 187 days using a visual analogue scale (VAS. In addition, libido, tiredness, and urinary, sleep, and mood complaints were also evaluated. Results. Women after RCE intervention (both groups reported better subjective improvement of scalp hair and skin status, libido, mood, sleep, and tiredness. Improvement of urinary complaints, nail, body hair, and mucosa (oral, nasal, and ocular status did not differ between treatment phases (intra- and intergroup. Overall satisfaction with treatment was reported higher after RCE intervention (both groups as compared to placebo. Conclusion. RCE supplementation exerted a subject improvement of scalp hair and skin status as well as libido, mood, sleep, and tiredness in postmenopausal women.

  14. Left Atrial Appendage: Physiology, Pathology, and Role as a Therapeutic Target

    Directory of Open Access Journals (Sweden)

    Damiano Regazzoli

    2015-01-01

    Full Text Available Atrial fibrillation (AF is the most common clinically relevant cardiac arrhythmia. AF poses patients at increased risk of thromboembolism, in particular ischemic stroke. The CHADS2 and CHA2DS2-VASc scores are useful in the assessment of thromboembolic risk in nonvalvular AF and are utilized in decision-making about treatment with oral anticoagulation (OAC. However, OAC is underutilized due to poor patient compliance and contraindications, especially major bleedings. The Virchow triad synthesizes the pathogenesis of thrombogenesis in AF: endocardial dysfunction, abnormal blood stasis, and altered hemostasis. This is especially prominent in the left atrial appendage (LAA, where the low flow reaches its minimum. The LAA is the remnant of the embryonic left atrium, with a complex and variable morphology predisposing to stasis, especially during AF. In patients with nonvalvular AF, 90% of thrombi are located in the LAA. So, left atrial appendage occlusion could be an interesting and effective procedure in thromboembolism prevention in AF. After exclusion of LAA as an embolic source, the remaining risk of thromboembolism does not longer justify the use of oral anticoagulants. Various surgical and catheter-based methods have been developed to exclude the LAA. This paper reviews the physiological and pathophysiological role of the LAA and catheter-based methods of LAA exclusion.

  15. Analytical method for the attitude stability of partially liquid filled spacecraft with flexible appendage

    Science.gov (United States)

    Yan, Yulong; Yue, Baozeng

    2016-11-01

    In this paper, the attitude stability of liquid-filled spacecraft with flexible appendage is investigated. The motion of liquid sloshing is modeled as the spherical pendulum, and the flexible appendage is approached by a linear shearing beam. Nonlinear dynamic equations of the coupled system are derived from the Hamiltonian. The stability of the coupled system was analyzed by using the energy-Casimir method, and the nonlinear stability theorem of the coupled spacecraft system was also obtained. Through numerical computation, the correctness of the proposed theorem is verified and the boundary curves of the stable region are presented. The increase of the angular velocity and flexible attachment length will weaken the attitude stability, and the change of the filled ratio of liquid fuel tank has a different influence on the stability of the coupled spacecraft, depending on the different conditions. The attitude stability analysis of the coupled spacecraft system in this context is useful for selecting appropriate parameters in the complex spacecraft design.

  16. Robotic and mathematical modeling reveal general principles of appendage control and coordination in terrestrial locomotion

    Science.gov (United States)

    McInroe, Benjamin; Astley, Henry; Gong, Chaohui; Kawano, Sandy; Schiebel, Perrin; Choset, Howie; Goldman, Daniel I.

    The transition from aquatic to terrestrial life presented new challenges to early walkers, necessitating robust locomotion on complex, flowable substrates (e.g. sand, mud). Locomotion on such substrates is sensitive to limb morphology and kinematics. Although early walker morphologies are known, principles of appendage control remain elusive. To reveal limb control strategies that facilitated the invasion of land, we study both robotic and mathematical models. Robot experiments show that an active tail is critical for robust locomotion on granular media, enabling locomotion even with poor foot placement and limited ability to lift the body. Using a granular resistive force theory model, we construct connection vector fields that reveal how appendage coordination and terrain inclination impact locomotor performance. This model replicates experimental results, showing that moving limbs/tail in phase is most effective (suggesting a locomotor template). Varying limb trajectories and contacts, we find gaits for which tail use can be neutral or harmful, suggesting limb-tail coordination to be a nontrivial aspect of locomotion. Our findings show that robot experiments coupled with geometric mechanics provide a general framework to reveal principles of robust terrestrial locomotion. This work was supported by NSF PoLS.

  17. Surgical Left Atrial Appendage Exclusion Does Not Impair Left Atrial Contraction Function: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Gijs E. De Maat

    2015-01-01

    Full Text Available Background. In order to reduce stroke risk, left atrial appendage amputation (LAAA is widely adopted in recent years. The effect of LAAA on left atrial (LA function remains unknown. The objective of present study was to assess the effect of LAAA on LA function. Methods. Sixteen patients with paroxysmal AF underwent thoracoscopic, surgical PVI with LAAA (LAAA group, and were retrospectively matched with 16 patients who underwent the same procedure without LAA amputation (non-LAAA group. To objectify LA function, transthoracic echocardiography with 2D Speckle Tracking was performed before surgery and at 12 months follow-up. Results. Mean age was 57 ± 9 years, 84% were male. Baseline characteristics did not differ significantly except for systolic blood pressure (p=0.005. In both groups, the contractile LA function and LA ejection fraction were not significantly reduced. However, the conduit and reservoir function were significantly decreased at follow-up, compared to baseline. The reduction of strain and strain rate was not significantly different between groups. Conclusions. In this retrospective, observational matched group comparison with a convenience sample size of 16 patients, findings suggest that LAAA does not impair the contractile LA function when compared to patients in which the appendage was unaddressed. However, the LA conduit and reservoir function are reduced in both the LAAA and non-LAAA group. Our data suggest that the LAA can be removed without late LA functional consequences.

  18. Peri-procedural silent cerebral infarcts after left atrial appendage occlusion.

    Science.gov (United States)

    Laible, M; Möhlenbruch, M; Horstmann, S; Pfaff, J; Geis, N A; Pleger, S; Schüler, S; Rizos, T; Bendszus, M; Veltkamp, R

    2017-01-01

    To determine the rate of peri-interventional silent brain infarcts after left atrial appendage occlusion (LAAO). In this prospective, uncontrolled single-center pilot study, consecutive patients with atrial fibrillation undergoing LAAO between July 2013 and January 2016 were included. The Amplatzer Cardiac Plug, WATCHMAN or Amulet device was used. A neurological examination and cranial magnetic resonance imaging (MRI) were performed within 48 h before and after the procedure. MRI was evaluated for new diffusion-weighted imaging (DWI) hyperintensities, cerebral microbleeds (CMBs) and white-matter lesions (WMLs). Left atrial appendage occlusion was performed in 21 patients (mean age, 73.2 ± 9.5 years). Main reasons for LAAO were previous intracerebral hemorrhage (n = 11) and major systemic bleeding (n = 6). No clinically overt stroke occurred peri-interventionally. After the intervention, one patient had a small cerebellar hyperintensity on DWI (4.8%; 95% confidence interval, 0.0-14.3) that was not present on the MRI 1 day before the procedure. Among 11 patients with available MRI just before LAAO, there were no significant changes in the number of CMBs and the severity of WMLs after LAAO. This study of peri-interventional MRI in LAAO suggests a low rate of silent peri-procedural infarcts in this elderly population. Confirmation in larger studies is needed. © 2016 EAN.

  19. Connexins and pannexins in the integumentary system: the skin and appendages.

    Science.gov (United States)

    Faniku, Chrysovalantou; Wright, Catherine S; Martin, Patricia E

    2015-08-01

    The integumentary system comprises the skin and its appendages, which includes hair, nails, feathers, sebaceous and eccrine glands. In this review, we focus on the expression profile of connexins and pannexins throughout the integumentary system in mammals, birds and fish. We provide a picture of the complexity of the connexin/pannexin network illustrating functional importance of these proteins in maintaining the integrity of the epidermal barrier. The differential regulation and expression of connexins and pannexins during skin renewal, together with a number of epidermal, hair and nail abnormalities associated with mutations in connexins, emphasize that the correct balance of connexin and pannexin expression is critical for maintenance of the skin and its appendages with both channel and non-channel functions playing profound roles. Changes in connexin expression during both hair and feather regeneration provide suggestions of specialized communication compartments. Finally, we discuss the potential use of zebrafish as a model for connexin skin biology, where evidence mounts that differential connexin expression is involved in skin patterning and pigmentation.

  20. Novel C3-symmetric molecular scaffolds with potential facial differentiation.

    Science.gov (United States)

    Hennrich, Gunther; Lynch, Vincent M; Anslyn, Eric V

    2002-05-17

    The conversion of 1,3,5-substituted benzene and mesitylene by electrophilic aromatic substitution and Sonogashira cross-coupling, respectively, furnished the C3-symmetric, hexasubstituted benzene derivatives 1 and 2 with an alternating substitution pattern. Based on the molecular scaffolds obtained, the two systems serve as model compounds for novel receptor molecules with distinct geometric features. X-ray structures have been obtained for 1 and 2, which are discussed in regard to their aptitude as receptor platforms or supramolecular building blocks. By looking at the rotational barriers for the functional groups placed around the molecular scaffolds by variable temperature 1H NMR spectroscopy, 1 and 2 turn out to exist in rapidly interconverting conformations. The alignment of these potential binding groups around the molecular scaffolds should be strongly biased by specific interactions with suitable guest molecules.

  1. Electrospun multifunctional tissue engineering scaffolds

    Science.gov (United States)

    Wang, Chong; Wang, Min

    2014-03-01

    Tissue engineering holds great promises in providing successful treatments of human body tissue loss that current methods are unable to treat or unable to achieve satisfactory clinical outcomes. In scaffold-based tissue engineering, a highperformance scaffold underpins the success of a tissue engineering strategy and a major direction in the field is to create multifunctional tissue engineering scaffolds for enhanced biological performance and for regenerating complex body tissues. Electrospinning can produce nanofibrous scaffolds that are highly desirable for tissue engineering. The enormous interest in electrospinning and electrospun fibrous structures by the science, engineering and medical communities has led to various developments of the electrospinning technology and wide investigations of electrospun products in many industries, including biomedical engineering, over the past two decades. It is now possible to create novel, multicomponent tissue engineering scaffolds with multiple functions. This article provides a concise review of recent advances in the R & D of electrospun multifunctional tissue engineering scaffolds. It also presents our philosophy and research in the designing and fabrication of electrospun multicomponent scaffolds with multiple functions.

  2. Handcrafted multilayer PDMS microchannel scaffolds for peripheral nerve regeneration.

    Science.gov (United States)

    Hossain, Ridwan; Kim, Bongkyun; Pankratz, Rachel; Ajam, Ali; Park, Sungreol; Biswal, Sibani L; Choi, Yoonsu

    2015-12-01

    Injuries that result in the loss of limb functionality may be caused by the severing of the peripheral nerves within the affected limb. Several bioengineered peripheral nerve scaffolds have been developed in order to provide the physical support and topographical guidance necessary for the naturally disorganized axon outgrowth to reattach to distal nerve stumps as an alternative to other procedures, like nerve grafting. PDMS has been chosen for the base material of the scaffolds due to its biocompatibility, flexibility, transparency, and well-developed fabrication techniques. The process of observing the axon outgrowth across the nerve gaps with PDMS scaffolds has been challenging due to the limited number and fineness of longitudinal sections that can be extracted from harvested nerve tissue samples after implantation. To address this, multilayer microchannel scaffolds were developed with the object of providing more refined longitudinal observation of axon outgrowth by longitudinally 'sectioning' the device during fabrication, removing the need for much of the sample preparation process. This device was then implanted into the sciatic nerves of Lewis rats, and then harvested after two and four weeks to analyze the difference in nerve regeneration between two different time periods. The present layer by layer structure, which is separable after nerve regeneration and is treated as an individual layer during the histology process, provides the details of biological events during axonal regeneration. Confocal microscopic imaging showed the details of peripheral nerve regeneration including nerve branches and growth cones observable from within the microchannels of the multilayer PDMS microchannel scaffolds.

  3. Novel scaffold design with multi-grooved PLA fibers

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Sangwon; King, Martin W [Fiber and Polymer Science, North Carolina State University, Raleigh, NC (United States); Gamcsik, Mike P, E-mail: martin_king@ncsu.edu [Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina Chapel Hill, NC (United States)

    2011-08-15

    A novel prototype nonwoven textile structure containing polylactide (PLA) multigrooved fibers has been proposed as a possible scaffold material for superior cell attachment and proliferation. Grooved cross-sectional fibers with larger surface area were obtained by a bi-component spinning system and the complete removal of the sacrificial component was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray photon spectroscopy (XPS) analysis. These PLA nonwoven scaffolds containing the grooved fibers exhibited enhanced wettability, greater flexibility and tensile properties, and a larger surface area compared to a traditional PLA nonwoven fabric containing round fibers. To evaluate cellular attachment on the two types of PLA nonwoven scaffolds, NIH 3T3 fibroblasts were cultured for up to 12 days. It was evident that the initial cellular attachment was superior on the scaffold with grooved fibers, which was confirmed by MTT viability assay (p < 0.01) and SEM analysis. In the future, by modulating the size of the grooves on the fibers, such a scaffold material with a large surface area could serve as an alternative matrix for culturing different types of cells.

  4. Decellularized Human Skeletal Muscle as Biologic Scaffold for Reconstructive Surgery

    Directory of Open Access Journals (Sweden)

    Andrea Porzionato

    2015-07-01

    Full Text Available Engineered skeletal muscle tissues have been proposed as potential solutions for volumetric muscle losses, and biologic scaffolds have been obtained by decellularization of animal skeletal muscles. The aim of the present work was to analyse the characteristics of a biologic scaffold obtained by decellularization of human skeletal muscles (also through comparison with rats and rabbits and to evaluate its integration capability in a rabbit model with an abdominal wall defect. Rat, rabbit and human muscle samples were alternatively decellularized with two protocols: n.1, involving sodium deoxycholate and DNase I; n.2, trypsin-EDTA and Triton X-NH4OH. Protocol 2 proved more effective, removing all cellular material and maintaining the three-dimensional networks of collagen and elastic fibers. Ultrastructural analyses with transmission and scanning electron microscopy confirmed the preservation of collagen, elastic fibres, glycosaminoglycans and proteoglycans. Implantation of human scaffolds in rabbits gave good results in terms of integration, although recellularization by muscle cells was not completely achieved. In conclusion, human skeletal muscles may be effectively decellularized to obtain scaffolds preserving the architecture of the extracellular matrix and showing mechanical properties suitable for implantation/integration. Further analyses will be necessary to verify the suitability of these scaffolds for in vitro recolonization by autologous cells before in vivo implantation.

  5. Scaffolding Biomaterials for Cartilage Regeneration

    Directory of Open Access Journals (Sweden)

    Zhen Cao

    2014-01-01

    Full Text Available Completely repairing of damaged cartilage is a difficult procedure. In recent years, the use of tissue engineering approach in which scaffolds play a vital role to regenerate cartilage has become a new research field. Investigating the advances in biological cartilage scaffolds has been regarded as the main research direction and has great significance for the construction of artificial cartilage. Native biological materials and synthetic polymeric materials have their advantages and disadvantages. The disadvantages can be overcome through either physical modification or biochemical modification. Additionally, developing composite materials, biomimetic materials, and nanomaterials can make scaffolds acquire better biocompatibility and mechanical adaptability.

  6. Exploring the scaffold universe of kinase inhibitors.

    Science.gov (United States)

    Hu, Ye; Bajorath, Jürgen

    2015-01-08

    The scaffold concept was applied to systematically determine, analyze, and compare core structures of kinase inhibitors. From publicly available inhibitors of the human kinome, scaffolds and cyclic skeletons were systematically extracted and organized taking activity data, structural relationships, and retrosynthetic criteria into account. Scaffold coverage varied greatly across the kinome, and many scaffolds representing compounds with different activity profiles were identified. The majority of kinase inhibitor scaffolds were involved in well-defined yet distinct structural relationships, which had different consequences on compound activity. Scaffolds exclusively representing highly potent compounds were identified as well as structurally analogous scaffolds with very different degrees of promiscuity. Scaffold relationships presented herein suggest a variety of hypotheses for inhibitor design. Our detailed organization of the kinase inhibitor scaffold universe with respect to different activity and structural criteria, all scaffolds, and the original compound data assembled for our analysis are made freely available.

  7. A Conserved MicroRNA Regulatory Circuit Is Differentially Controlled during Limb/Appendage Regeneration.

    Directory of Open Access Journals (Sweden)

    Benjamin L King

    Full Text Available Although regenerative capacity is evident throughout the animal kingdom, it is not equally distributed throughout evolution. For instance, complex limb/appendage regeneration is muted in mammals but enhanced in amphibians and teleosts. The defining characteristic of limb/appendage regenerative systems is the formation of a dedifferentiated tissue, termed blastema, which serves as the progenitor reservoir for regenerating tissues. In order to identify a genetic signature that accompanies blastema formation, we employ next-generation sequencing to identify shared, differentially regulated mRNAs and noncoding RNAs in three different, highly regenerative animal systems: zebrafish caudal fins, bichir pectoral fins and axolotl forelimbs.These studies identified a core group of 5 microRNAs (miRNAs that were commonly upregulated and 5 miRNAs that were commonly downregulated, as well as 4 novel tRNAs fragments with sequences conserved with humans. To understand the potential function of these miRNAs, we built a network of 1,550 commonly differentially expressed mRNAs that had functional relationships to 11 orthologous blastema-associated genes. As miR-21 was the most highly upregulated and most highly expressed miRNA in all three models, we validated the expression of known target genes, including the tumor suppressor, pdcd4, and TGFβ receptor subunit, tgfbr2 and novel putative target genes such as the anti-apoptotic factor, bcl2l13, Choline kinase alpha, chka and the regulator of G-protein signaling, rgs5.Our extensive analysis of RNA-seq transcriptome profiling studies in three regenerative animal models, that diverged in evolution ~420 million years ago, reveals a common miRNA-regulated genetic network of blastema genes. These comparative studies extend our current understanding of limb/appendage regeneration by identifying previously unassociated blastema genes and the extensive regulation by miRNAs, which could serve as a foundation for future

  8. A Conserved MicroRNA Regulatory Circuit Is Differentially Controlled during Limb/Appendage Regeneration

    Science.gov (United States)

    King, Benjamin L.; Yin, Viravuth P.

    2016-01-01

    Background Although regenerative capacity is evident throughout the animal kingdom, it is not equally distributed throughout evolution. For instance, complex limb/appendage regeneration is muted in mammals but enhanced in amphibians and teleosts. The defining characteristic of limb/appendage regenerative systems is the formation of a dedifferentiated tissue, termed blastema, which serves as the progenitor reservoir for regenerating tissues. In order to identify a genetic signature that accompanies blastema formation, we employ next-generation sequencing to identify shared, differentially regulated mRNAs and noncoding RNAs in three different, highly regenerative animal systems: zebrafish caudal fins, bichir pectoral fins and axolotl forelimbs. Results These studies identified a core group of 5 microRNAs (miRNAs) that were commonly upregulated and 5 miRNAs that were commonly downregulated, as well as 4 novel tRNAs fragments with sequences conserved with humans. To understand the potential function of these miRNAs, we built a network of 1,550 commonly differentially expressed mRNAs that had functional relationships to 11 orthologous blastema-associated genes. As miR-21 was the most highly upregulated and most highly expressed miRNA in all three models, we validated the expression of known target genes, including the tumor suppressor, pdcd4, and TGFβ receptor subunit, tgfbr2 and novel putative target genes such as the anti-apoptotic factor, bcl2l13, Choline kinase alpha, chka and the regulator of G-protein signaling, rgs5. Conclusions Our extensive analysis of RNA-seq transcriptome profiling studies in three regenerative animal models, that diverged in evolution ~420 million years ago, reveals a common miRNA-regulated genetic network of blastema genes. These comparative studies extend our current understanding of limb/appendage regeneration by identifying previously unassociated blastema genes and the extensive regulation by miRNAs, which could serve as a foundation

  9. Fibrosis and electrophysiological characteristics of the atrial appendage in patients with atrial fibrillation and structural heart disease

    NARCIS (Netherlands)

    Brakel, T.J. van; Krieken, T. van der; Westra, S.W.; Laak, J.A.W.M. van der; Smeets, J.L.R.M.; Swieten, H.A. van

    2013-01-01

    PURPOSE: This study was conducted to investigate the degree of fibrosis in atrial appendages of patients with and without atrial fibrillation (AF) undergoing cardiac surgery. In addition, we hypothesized that areas of atrial fibrosis can be identified by electrogram fractionation and low voltage for

  10. The chemosensory appendage proteome of Amblyomma americanum (Acari: Ixodidae) reveals putative odorant-binding and other chemoreception-related proteins

    Science.gov (United States)

    Proteomic analyses were done on 2 chemosensory appendages of the lone star tick, Amblyomma americanum. Proteins in the fore tarsi, which contain the olfactory Haller's organ, and in the palps, that include gustatory sensilla, were compared with proteins in the third tarsi. Also, male and female tick...

  11. Three-dimensionally preserved minute larva of a great-appendage arthropod from the early Cambrian Chengjiang biota

    Science.gov (United States)

    Liu, Yu; Melzer, Roland R.; Haug, Joachim T.; Haug, Carolin; Briggs, Derek E. G.; Hörnig, Marie K.; He, Yu-yang; Hou, Xian-guang

    2016-05-01

    A three-dimensionally preserved 2-mm-long larva of the arthropod Leanchoilia illecebrosa from the 520-million-year-old early Cambrian Chengjiang biota of China represents the first evidence, to our knowledge, of such an early developmental stage in a short-great-appendage (SGA) arthropod. The larva possesses a pair of three-fingered great appendages, a hypostome, and four pairs of well-developed biramous appendages. More posteriorly, a series of rudimentary limb Anlagen revealed by X-ray microcomputed tomography shows a gradient of decreasing differentiation toward the rear. This, and postembryonic segment addition at the putative growth zone, are features of late-stage metanauplii of eucrustaceans. L. illecebrosa and other SGA arthropods, however, are considered representative of early chelicerates or part of the stem lineage of all euarthropods. The larva of an early Cambrian SGA arthropod with a small number of anterior segments and their respective appendages suggests that posthatching segment addition occurred in the ancestor of Euarthropoda.

  12. Enhanced mechanical strength and biocompatibility of electrospun polycaprolactone-gelatin scaffold with surface deposited nano-hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Jaiswal, A.K. [Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076 (India); Chhabra, H. [Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076 (India); Soni, V.P. [Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076 (India); Bellare, J.R., E-mail: jb@iitb.ac.in [Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076 (India)

    2013-05-01

    In this study for the first time, we compared physico-chemical and biological properties of polycaprolactone-gelatin-hydroxyapatite scaffolds of two types: one in which the nano-hydroxyapatite (n-HA) was deposited on the surface of electrospun polycaprolactone-gelatin (PCG) fibers via alternate soaking process (PCG-HA{sub AS}) and other in which hydroxyapatite (HA) powders were blended in electrospinning solution of PCG (PCG-HA{sub B}). The microstructure of fibers was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which showed n-HA particles on the surface of the PCG-HA{sub AS} scaffold and embedded HA particles in the interior of the PCG-HA{sub B} fibers. PCG-HA{sub AS} fibers exhibited the better Young's moduli and tensile strength as compared to PCG-HA{sub B} fibers. Biological properties such as cell proliferation, cell attachment and alkaline phosphatase activity (ALP) were determined by growing human osteosarcoma cells (MG-63) over the scaffolds. Cell proliferation and confocal results clearly indicated that the presence of hydroxyapatite on the surface of the PCG-HA{sub AS} scaffold promoted better cellular adhesion and proliferation as compared to PCG-HA{sub B} scaffold. ALP activity was also observed better in alternate soaked PCG scaffold as compared to PCG-HA{sub B} scaffold. Mechanical strength and biological properties clearly demonstrate that surface deposited HA scaffold prepared by alternate soaking method may find application in bone tissue engineering. - Highlights: ► PCG-HA scaffold was prepared by two methods: blending and by alternate soaking. ► Uniform n-HA was found at the nanofiber surface with the alternate soaking method. ► PCG-HA{sub AS} scaffold showed better mechanical strength compared to PCG-HA{sub B} fibers. ► Cell adhesion, proliferation and ALP activity were also better in PCG-HA{sub AS}.

  13. Unusual anal fin in a Devonian jawless vertebrate reveals complex origins of paired appendages.

    Science.gov (United States)

    Sansom, Robert S; Gabbott, Sarah E; Purnell, M A

    2013-06-23

    Jawed vertebrates (gnathostomes) have undergone radical anatomical and developmental changes in comparison with their jawless cousins (cyclostomes). Key among these is paired appendages (fins, legs and wings), which first evolved at some point on the gnathostome stem. The anatomy of fossil stem gnathostomes is, therefore, fundamental to our understanding of the nature and timing of the origin of this complex innovation. Here, we show that Euphanerops, a fossil jawless fish from the Devonian, possessed paired anal-fin radials, but no pectoral or pelvic fins. This unique condition occurs at an early stage on the stem-gnathostome lineage. This condition, and comparison with the varied condition of paired fins in other ostracoderms, indicates that there was a large amount of developmental plasticity during this episode-rather than a gradual evolution of this complex feature. Apparently, a number of different clades were exploring morphospace or undergoing multiple losses.

  14. Radiofrequency Ablation of a Left Atrial Appendage Tachycardia on ECMO Support

    Directory of Open Access Journals (Sweden)

    Mohsin Khan

    2013-01-01

    Full Text Available Extracorporeal membrane oxygenation (ECMO has been utilized in the pediatric population for cardiogenic shock secondary to medically intractable arrhythmias. There is limited experience with cardiac radiofrequency ablation (RFA on these patients while on ECMO. A 7-year-old girl presented with a tachycardia-mediated cardiomyopathy secondary to a left atrial appendage tachycardia. She suffered a cardiac arrest due to pulseless electrical activity and was placed on ECMO. Due to elevated left atrial pressures and the refractoriness of her arrhythmia to cardioversion and antiarrhythmic therapy, while on ECMO, blade atrial septostomy and radiofrequency ablation were performed. The patient tolerated the procedure well and was successfully decannulated. Her cardiac function normalized within four weeks of the ablation procedure. Twelve months after the procedure, she remains completely well, with no symptoms or tachycardia.

  15. Pleomorphic adenoma with squamous and appendageal metaplasia mimicking mucoepidermoid carcinoma on cytology

    Directory of Open Access Journals (Sweden)

    Batrani Meenakshi

    2009-01-01

    Full Text Available Background: Histological diversity is the hallmark of pleomorphic adenoma, the most common salivary gland tumor. It may cause difficulty in cytological interpretation, due to limited and selective sampling. Case presentation: A 16-year-old female patient presented with right cheek swelling. Fine needle aspiration cytology showed squamous cells, basaloid cells, and foamy cells, along with extracellular keratin and foreign body giant cells. Characteristic metachromatic fibrillary chondromyxoid stroma, which is usually seen in pleomorphic adenoma, was not seen in the aspirate. A diagnosis of mucoepidermoid carcinoma was given on cytology. Subsequent resection revealed an encapsulated pleomorphic adenoma, with extensive squamous metaplasia and appendageal differentiation on histology. Conclusion: This case illustrates that pleomorphic adenoma with squamous metaplasia presents a potential for misinterpretation as mucoepidermoid carcinoma on cytology. We discuss the various pitfalls and the features that are helpful in distinguishing these two lesions.

  16. A shared role for sonic hedgehog signalling in patterning chondrichthyan gill arch appendages and tetrapod limbs.

    Science.gov (United States)

    Gillis, J Andrew; Hall, Brian K

    2016-04-15

    Chondrichthyans (sharks, skates, rays and holocephalans) possess paired appendages that project laterally from their gill arches, known as branchial rays. This led Carl Gegenbaur to propose that paired fins (and hence tetrapod limbs) originally evolved via transformation of gill arches. Tetrapod limbs are patterned by asonic hedgehog(Shh)-expressing signalling centre known as the zone of polarising activity, which establishes the anteroposterior axis of the limb bud and maintains proliferative expansion of limb endoskeletal progenitors. Here, we use loss-of-function, label-retention and fate-mapping approaches in the little skate to demonstrate that Shh secretion from a signalling centre in the developing gill arches establishes gill arch anteroposterior polarity and maintains the proliferative expansion of branchial ray endoskeletal progenitor cells. These findings highlight striking parallels in the axial patterning mechanisms employed by chondrichthyan branchial rays and paired fins/limbs, and provide mechanistic insight into the anatomical foundation of Gegenbaur's gill arch hypothesis.

  17. Chaotic attitude and reorientation maneuver for completely liquid-filled spacecraft with flexible appendage

    Institute of Scientific and Technical Information of China (English)

    Baozeng Yue

    2009-01-01

    The present paper investigates the chaotic attitude dynamics and reorientation maneuver for completely viscous liquid-filled spacecraft with flexible appendage. All of the equations of motion are derived by using Lagrangian mechanics and then transformed into a form consisting of an unperturbed part plus perturbed terms so that the system's nonlinear characteristics can be exploited in phase space.Emphases are laid on the chaotic attitude dynamics produced from certain sets of physical parameter values of the spacecraft when energy dissipation acts to derive the body from minor to major axis spin. Numerical solutions of these equations show that the attitude dynamics of liquid-filled flexible spacecraft possesses characteristics common to random, nonperiodic solutions and chaos, and it is demonstrated that the desired reorientation maneuver is guaranteed by using a pair of thruster impulses. The control strategy for reorientation maneuver is designed and the numerical simulation results are presented for both the uncontrolled and controlled spins transition.

  18. Hierarchical assembly of centriole subdistal appendages via centrosome binding proteins CCDC120 and CCDC68.

    Science.gov (United States)

    Huang, Ning; Xia, Yuqing; Zhang, Donghui; Wang, Song; Bao, Yitian; He, Runsheng; Teng, Junlin; Chen, Jianguo

    2017-04-19

    In animal cells, the centrosome is the main microtubule-organizing centre where microtubules are nucleated and anchored. The centriole subdistal appendages (SDAs) are the key structures that anchor microtubules in interphase cells, but the composition and assembly mechanisms of SDAs are not well understood. Here, we reveal that centrosome-binding proteins, coiled-coil domain containing (CCDC) 120 and CCDC68 are two novel SDA components required for hierarchical SDA assembly in human cells. CCDC120 is anchored to SDAs by ODF2 and recruits CEP170 and Ninein to the centrosome through different coiled-coil domains at its N terminus. CCDC68 is a CEP170-interacting protein that competes with CCDC120 in recruiting CEP170 to SDAs. Furthermore, CCDC120 and CCDC68 are required for centrosome microtubule anchoring. Our findings elucidate the molecular basis for centriole SDA hierarchical assembly and microtubule anchoring in human interphase cells.

  19. The chicken-wing morphology: an anatomical challenge for left atrial appendage occlusion.

    Science.gov (United States)

    Freixa, Xavier; Tzikas, Apostolos; Basmadjian, Arsène; Garceau, Patrick; Ibrahim, Rèda

    2013-10-01

    To describe the particular assessment and closure strategy that was followed in patients with left atrial appendages (LAA) with an early and severe bend. The presence of a chicken-wing morphology with an early and severe bend constitutes one of the most difficult anatomical settings for transcatheter LAA occlusion. Between November 2009 and December 2012, patients who presented chicken-wing LAA with an early (Amulet (n = 3). Successful occlusion was achieved in all patients. None of them presented any procedural complication. Follow-up transesophageal echocardiography at 3 months showed successful LAA sealing in all patients and no device embolization or thrombosis. According to our results, the pre-specified closing implantation technique for chicken-wing LAAs with an early and severe bend might be a valid strategy for this challenging anatomical setting. Further cases will be necessary to confirm the results. © 2013, Wiley Periodicals, Inc.

  20. Hierarchical assembly of centriole subdistal appendages via centrosome binding proteins CCDC120 and CCDC68

    Science.gov (United States)

    Huang, Ning; Xia, Yuqing; Zhang, Donghui; Wang, Song; Bao, Yitian; He, Runsheng; Teng, Junlin; Chen, Jianguo

    2017-01-01

    In animal cells, the centrosome is the main microtubule-organizing centre where microtubules are nucleated and anchored. The centriole subdistal appendages (SDAs) are the key structures that anchor microtubules in interphase cells, but the composition and assembly mechanisms of SDAs are not well understood. Here, we reveal that centrosome-binding proteins, coiled-coil domain containing (CCDC) 120 and CCDC68 are two novel SDA components required for hierarchical SDA assembly in human cells. CCDC120 is anchored to SDAs by ODF2 and recruits CEP170 and Ninein to the centrosome through different coiled-coil domains at its N terminus. CCDC68 is a CEP170-interacting protein that competes with CCDC120 in recruiting CEP170 to SDAs. Furthermore, CCDC120 and CCDC68 are required for centrosome microtubule anchoring. Our findings elucidate the molecular basis for centriole SDA hierarchical assembly and microtubule anchoring in human interphase cells. PMID:28422092

  1. Modeling on thermally induced coupled micro-motions of satellite with complex flexible appendages

    Directory of Open Access Journals (Sweden)

    Zhicheng Zhou

    2015-06-01

    Full Text Available To describe the characteristics of thermally induced coupled micro-motions more exactly, a numerical model is proposed for a satellite system consisting of a rigid body and the complex appendages. The coupled governing equations including the effects of transient temperature differences are formulated within the framework of the Lagrangian Method based on the finite element models of flexible structures. Meanwhile, the problem of coupling between attitude motions of rigid body and vibrations of flexible attachments are addressed with explicit expressions. Thermally induced micro-motions are examined in detail for a simple satellite with a large solar panel under the disturbance of thermal environment from earth shadow to sunlight area in the earth orbit. The results show that the thermal–mechanical performances of an on-orbit satellite can be well predicted by the proposed finite element model.

  2. Multilayered Magnetic Gelatin Membrane Scaffolds

    Science.gov (United States)

    Samal, Sangram K.; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L.; Dediu, V. Alek

    2016-01-01

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial–magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  3. Division of labor: subsets of dorsal-appendage-forming cells control the shape of the entire tube.

    Science.gov (United States)

    Boyle, Michael J; French, Rachael L; Cosand, K Amber; Dorman, Jennie B; Kiehart, Daniel P; Berg, Celeste A

    2010-10-01

    The function of an organ relies on its form, which in turn depends on the individual shapes of the cells that create it and the interactions between them. Despite remarkable progress in the field of developmental biology, how cells collaborate to make a tissue remains an unsolved mystery. To investigate the mechanisms that determine organ structure, we are studying the cells that form the dorsal appendages (DAs) of the Drosophila melanogaster eggshell. These cells consist of two differentially patterned subtypes: roof cells, which form the outward-facing roof of the lumen, and floor cells, which dive underneath the roof cells to seal off the floor of the tube. In this paper, we present three lines of evidence that reveal a further stratification of the DA-forming epithelium. Laser ablation of only a few cells in the anterior of the region causes a disproportionately severe shortening of the appendage. Genetic alteration through the twin peaks allele of tramtrack69 (ttk(twk)), a female-sterile mutation that leads to severely shortened DAs, causes no such shortening when removed from a majority of the DA-forming cells, but rather, produces short appendages only when removed from cells in the very anterior of the tube-forming tissue. Additionally we show that heterotrimeric G-protein function is required for DA morphogenesis. Like TTK69, Gbeta 13F is not required in all DA-forming follicle cells but only in the floor and leading roof cells. The different phenotypes that result from removal of Gbeta 13F from each region demonstrate a striking division of function between different DA-forming cells. Gbeta mutant floor cells are unable to control the width of the appendage while Gbeta mutant leading roof cells fail to direct the elongation of the appendage and the convergent-extension of the roof-cell population.

  4. Principles of appendage design in robots and animals determining terradynamic performance on flowable ground.

    Science.gov (United States)

    Qian, Feifei; Zhang, Tingnan; Korff, Wyatt; Umbanhowar, Paul B; Full, Robert J; Goldman, Daniel I

    2015-10-08

    Natural substrates like sand, soil, leaf litter and snow vary widely in penetration resistance. To search for principles of appendage design in robots and animals that permit high performance on such flowable ground, we developed a ground control technique by which the penetration resistance of a dry granular substrate could be widely and rapidly varied. The approach was embodied in a device consisting of an air fluidized bed trackway in which a gentle upward flow of air through the granular material resulted in a decreased penetration resistance. As the volumetric air flow, Q, increased to the fluidization transition, the penetration resistance decreased to zero. Using a bio-inspired hexapedal robot as a physical model, we systematically studied how locomotor performance (average forward speed, v(x)) varied with ground penetration resistance and robot leg frequency. Average robot speed decreased with increasing Q, and decreased more rapidly for increasing leg frequency, ω. A universal scaling model revealed that the leg penetration ratio (foot pressure relative to penetration force per unit area per depth and leg length) determined v(x) for all ground penetration resistances and robot leg frequencies. To extend our result to include continuous variation of locomotor foot pressure, we used a resistive force theory based terradynamic approach to perform numerical simulations. The terradynamic model successfully predicted locomotor performance for low resistance granular states. Despite variation in morphology and gait, the performance of running lizards, geckos and crabs on flowable ground was also influenced by the leg penetration ratio. In summary, appendage designs which reduce foot pressure can passively maintain minimal leg penetration ratio as the ground weakens, and consequently permits maintenance of effective locomotion over a range of terradynamically challenging surfaces.

  5. On dorsal prothoracic appendages in treehoppers (Hemiptera: Membracidae and the nature of morphological evidence.

    Directory of Open Access Journals (Sweden)

    István Mikó

    Full Text Available A spectacular hypothesis was published recently, which suggested that the "helmet" (a dorsal thoracic sclerite that obscures most of the body of treehoppers (Insecta: Hemiptera: Membracidae is connected to the 1st thoracic segment (T1; prothorax via a jointed articulation and therefore was a true appendage. Furthermore, the "helmet" was interpreted to share multiple characteristics with wings, which in extant pterygote insects are present only on the 2nd (T2 and 3rd (T3 thoracic segments. In this context, the "helmet" could be considered an evolutionary novelty. Although multiple lines of morphological evidence putatively supported the "helmet"-wing homology, the relationship of the "helmet" to other thoracic sclerites and muscles remained unclear. Our observations of exemplar thoraces of 10 hemipteran families reveal multiple misinterpretations relevant to the "helmet"-wing homology hypothesis as originally conceived: 1 the "helmet" actually represents T1 (excluding the fore legs; 2 the "T1 tergum" is actually the anterior dorsal area of T2; 3 the putative articulation between the "helmet" and T1 is actually the articulation between T1 and T2. We conclude that there is no dorsal, articulated appendage on the membracid T1. Although the posterior, flattened, cuticular evagination (PFE of the membracid T1 does share structural and genetic attributes with wings, the PFE is actually widely distributed across Hemiptera. Hence, the presence of this structure in Membracidae is not an evolutionary novelty for this clade. We discuss this new interpretation of the membracid T1 and the challenges of interpreting and representing morphological data more broadly. We acknowledge that the lack of data standards for morphology is a contributing factor to misinterpreted results and offer an example for how one can reduce ambiguity in morphology by referencing anatomical concepts in published ontologies.

  6. On dorsal prothoracic appendages in treehoppers (Hemiptera: Membracidae) and the nature of morphological evidence.

    Science.gov (United States)

    Mikó, István; Friedrich, Frank; Yoder, Matthew J; Hines, Heather M; Deitz, Lewis L; Bertone, Matthew A; Seltmann, Katja C; Wallace, Matthew S; Deans, Andrew R

    2012-01-01

    A spectacular hypothesis was published recently, which suggested that the "helmet" (a dorsal thoracic sclerite that obscures most of the body) of treehoppers (Insecta: Hemiptera: Membracidae) is connected to the 1st thoracic segment (T1; prothorax) via a jointed articulation and therefore was a true appendage. Furthermore, the "helmet" was interpreted to share multiple characteristics with wings, which in extant pterygote insects are present only on the 2nd (T2) and 3rd (T3) thoracic segments. In this context, the "helmet" could be considered an evolutionary novelty. Although multiple lines of morphological evidence putatively supported the "helmet"-wing homology, the relationship of the "helmet" to other thoracic sclerites and muscles remained unclear. Our observations of exemplar thoraces of 10 hemipteran families reveal multiple misinterpretations relevant to the "helmet"-wing homology hypothesis as originally conceived: 1) the "helmet" actually represents T1 (excluding the fore legs); 2) the "T1 tergum" is actually the anterior dorsal area of T2; 3) the putative articulation between the "helmet" and T1 is actually the articulation between T1 and T2. We conclude that there is no dorsal, articulated appendage on the membracid T1. Although the posterior, flattened, cuticular evagination (PFE) of the membracid T1 does share structural and genetic attributes with wings, the PFE is actually widely distributed across Hemiptera. Hence, the presence of this structure in Membracidae is not an evolutionary novelty for this clade. We discuss this new interpretation of the membracid T1 and the challenges of interpreting and representing morphological data more broadly. We acknowledge that the lack of data standards for morphology is a contributing factor to misinterpreted results and offer an example for how one can reduce ambiguity in morphology by referencing anatomical concepts in published ontologies.

  7. Left Atrial Appendage Closure Guided by Integrated Echocardiography and Fluoroscopy Imaging Reduces Radiation Exposure.

    Directory of Open Access Journals (Sweden)

    Christiane Jungen

    Full Text Available To investigate whether percutaneous left atrial appendage (LAA closure guided by automated real-time integration of 2D-/3D-transesophageal echocardiography (TEE and fluoroscopy imaging results in decreased radiation exposure.In this open-label single-center study LAA closure (AmplatzerTM Cardiac Plug was performed in 34 consecutive patients (8 women; 73.1±8.5 years with (n = 17, EN+ or without (n = 17, EN- integrated echocardiography/fluoroscopy imaging guidance (EchoNavigator® [EN]; Philips Healthcare. There were no significant differences in baseline characteristics between both groups. Successful LAA closure was documented in all patients. Radiation dose was reduced in the EN+ group about 52% (EN+: 48.5±30.7 vs. EN-: 93.9±64.4 Gy/cm2; p = 0.01. Corresponding to the radiation dose fluoroscopy time was reduced (EN+: 16.7±7 vs. EN-: 24.0±11.4 min; p = 0.035. These advantages were not at the cost of increased procedure time (89.6±28.8 vs. 90.1±30.2 min; p = 0.96 or periprocedural complications. Contrast media amount was comparable between both groups (172.3±92.7 vs. 197.5±127.8 ml; p = 0.53. During short-term follow-up of at least 3 months (mean: 8.1±5.9 months no device-related events occurred.Automated real-time integration of echocardiography and fluoroscopy can be incorporated into procedural work-flow of percutaneous left atrial appendage closure without prolonging procedure time. This approach results in a relevant reduction of radiation exposure.ClinicalTrials.gov NCT01262508.

  8. A sexually dimorphic corolla appendage affects pollen removal and floral longevity in gynodioecious Cyananthus delavayi (Campanulaceae.

    Directory of Open Access Journals (Sweden)

    Yang Niu

    Full Text Available The floral traits of bisexual flowers may evolve in response to selection on both male and female functions, but the relative importance of selection associated with each of these two aspects is poorly resolved. Sexually dimorphic traits in plants with unisexual flowers may reflect gender-specific selection, providing opportunities for gaining an increased understanding of the evolution of specific floral traits. We examined sexually dimorphic patterns of floral traits in perfect and female flowers of the gynodioecious species Cyananthus delavayi. A special corolla appendage, the throat hair, was investigated experimentally to examine its influences on male and female function. We found that perfect flowers have larger corollas and much longer throat hairs than female flowers, while female ones have much exerted stigmas. The presence of throat hairs prolonged the duration of pollen presentation by restricting the amount of pollen removed by pollen-collecting bees during each visit. Floral longevity was negatively related to the rate of pollen removal. When pollen removal rate was limited in perfect flowers, the duration of the female phases diminished with the increased male phase duration. There was a weak negative correlation between throat hair length and seed number per fruit in female flowers, but this correlation was not significant in perfect flowers. These results suggest that throat hairs may enhance male function in terms of prolonged pollen presentation. However, throat hairs have no obvious effect on female function in terms of seed number per fruit. The marked sexual dimorphism of this corolla appendage in C. delavayi is likely to have evolved and been maintained by gender-specific selection.

  9. Functionalizable oligoprolines as molecular scaffolds.

    Science.gov (United States)

    Nagel, Yvonne A; Kuemin, Michael; Wennemers, Helma

    2011-01-01

    Azidoproline (Azp) containing oligoprolines are conformationally well-defined, helical molecular scaffolds that allow for facile functionalization. Within this article we describe the synthesis of Azp-containing oligoprolines and different strategies to introduce functional moieties. In addition, the influence of factors such as substituents at the y-position of proline as well as functional groups at the termini on the conformational stability of the molecular scaffolds are briefly presented.

  10. Cytocompatibility of a silk fibroin tubular scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiannan, E-mail: wangjn@suda.edu.cn; Wei, Yali; Yi, Honggen; Liu, Zhiwu; Sun, Dan; Zhao, Huanrong

    2014-01-01

    Regenerated silk fibroin (SF) materials are increasingly used for tissue engineering applications. In order to explore the feasibility of a novel biomimetic silk fibroin tubular scaffold (SFTS) crosslinked by poly(ethylene glycol) diglycidyl ether (PEG-DE), biocompatibility with cells was evaluated. The novel biomimetic design of the SFTS consisted of three distinct layers: a regenerated SF intima, a silk braided media and a regenerated SF adventitia. The SFTS exhibited even silk fibroin penetration throughout the braid, forming a porous layered tube with superior mechanical, permeable and cell adhesion properties that are beneficial to vascular regeneration. Cytotoxicity and cell compatibility were tested on L929 cells and human umbilical vein endothelial cells (EA.hy926). DNA content analysis, scanning electron and confocal microscopies and MTT assay showed no inhibitory effects on DNA replication. Cell morphology, viability and proliferation were good for L929 cells, and satisfactory for EA.hy926 cells. Furthermore, the suture retention strength of the SFTS was about 23 N and the Young's modulus was 0.2–0.3 MPa. Collectively, these data demonstrate that PEG-DE crosslinked SFTS possesses the appropriate cytocompatibility and mechanical properties for use as vascular scaffolds as an alternative to vascular autografts. - Highlights: • A PEG-DE cross-linked small caliber porous silk fibroin tubular scaffold (SFTS) • PEG-DE cross-linked SF film had no inhibitory effect on DNA replication of cells. • Cells cultured on the SFTS showed good morphology, cell viability and proliferative activity. • SFTS would be beneficial to endothelialization. • SFTS had good suture retention strength and flexibility.

  11. Cephalic and limb anatomy of a new Isoxyid from the Burgess Shale and the role of "stem bivalved arthropods" in the disparity of the frontalmost appendage.

    Directory of Open Access Journals (Sweden)

    Cédric Aria

    Full Text Available We herein describe Surusicaris elegans gen. et sp. nov. (in Isoxyidae, amended, a middle (Series 3, Stage 5 Cambrian bivalved arthropod from the new Burgess Shale deposit of Marble Canyon (Kootenay National Park, British Columbia. Surusicaris exhibits 12 simple, partly undivided biramous trunk limbs with long tripartite caeca, which may illustrate a plesiomorphic "fused" condition of exopod and endopod. We construe also that the head is made of five somites (= four segments, including two eyes, one pair of anomalocaridid-like frontalmost appendages, and three pairs of poorly sclerotized uniramous limbs. This fossil may therefore be a candidate for illustrating the origin of the plesiomorphic head condition in euarthropods, and questions the significance of the "two-segmented head" in, e.g., fuxianhuiids. The frontalmost appendage in isoxyids is intriguingly disparate, bearing similarities with both dinocaridids and euarthropods. In order to evaluate the relative importance of bivalved arthropods, such as Surusicaris, in the hypothetical structuro-functional transition between the dinocaridid frontal appendage and the pre-oral-arguably deutocerebral-appendage of euarthropods, we chose a phenetic approach and computed morphospace occupancy for the frontalmost appendages of 36 stem and crown taxa. Results show different levels of evolutionary decoupling between frontalmost appendage disparity and body plans. Variance is greatest in dinocaridids and "stem bivalved" arthropods, but these groups do not occupy the morphospace homogeneously. Rather, the diversity of frontalmost appendages in "stem bivalved" arthropods, distinct in its absence of clear clustering, is found to link the morphologies of "short great appendages," chelicerae and antennules. This find fits the hypothesis of an increase in disparity of the deutocerebral appendage prior to its diversification in euarthropods, and possibly corresponds to its original time of development. The

  12. Cephalic and limb anatomy of a new Isoxyid from the Burgess Shale and the role of "stem bivalved arthropods" in the disparity of the frontalmost appendage.

    Science.gov (United States)

    Aria, Cédric; Caron, Jean-Bernard

    2015-01-01

    We herein describe Surusicaris elegans gen. et sp. nov. (in Isoxyidae, amended), a middle (Series 3, Stage 5) Cambrian bivalved arthropod from the new Burgess Shale deposit of Marble Canyon (Kootenay National Park, British Columbia). Surusicaris exhibits 12 simple, partly undivided biramous trunk limbs with long tripartite caeca, which may illustrate a plesiomorphic "fused" condition of exopod and endopod. We construe also that the head is made of five somites (= four segments), including two eyes, one pair of anomalocaridid-like frontalmost appendages, and three pairs of poorly sclerotized uniramous limbs. This fossil may therefore be a candidate for illustrating the origin of the plesiomorphic head condition in euarthropods, and questions the significance of the "two-segmented head" in, e.g., fuxianhuiids. The frontalmost appendage in isoxyids is intriguingly disparate, bearing similarities with both dinocaridids and euarthropods. In order to evaluate the relative importance of bivalved arthropods, such as Surusicaris, in the hypothetical structuro-functional transition between the dinocaridid frontal appendage and the pre-oral-arguably deutocerebral-appendage of euarthropods, we chose a phenetic approach and computed morphospace occupancy for the frontalmost appendages of 36 stem and crown taxa. Results show different levels of evolutionary decoupling between frontalmost appendage disparity and body plans. Variance is greatest in dinocaridids and "stem bivalved" arthropods, but these groups do not occupy the morphospace homogeneously. Rather, the diversity of frontalmost appendages in "stem bivalved" arthropods, distinct in its absence of clear clustering, is found to link the morphologies of "short great appendages," chelicerae and antennules. This find fits the hypothesis of an increase in disparity of the deutocerebral appendage prior to its diversification in euarthropods, and possibly corresponds to its original time of development. The analysis of this

  13. Cephalic and Limb Anatomy of a New Isoxyid from the Burgess Shale and the Role of “Stem Bivalved Arthropods” in the Disparity of the Frontalmost Appendage

    Science.gov (United States)

    Aria, Cédric; Caron, Jean-Bernard

    2015-01-01

    We herein describe Surusicaris elegans gen. et sp. nov. (in Isoxyidae, amended), a middle (Series 3, Stage 5) Cambrian bivalved arthropod from the new Burgess Shale deposit of Marble Canyon (Kootenay National Park, British Columbia). Surusicaris exhibits 12 simple, partly undivided biramous trunk limbs with long tripartite caeca, which may illustrate a plesiomorphic “fused” condition of exopod and endopod. We construe also that the head is made of five somites (= four segments), including two eyes, one pair of anomalocaridid-like frontalmost appendages, and three pairs of poorly sclerotized uniramous limbs. This fossil may therefore be a candidate for illustrating the origin of the plesiomorphic head condition in euarthropods, and questions the significance of the “two-segmented head” in, e.g., fuxianhuiids. The frontalmost appendage in isoxyids is intriguingly disparate, bearing similarities with both dinocaridids and euarthropods. In order to evaluate the relative importance of bivalved arthropods, such as Surusicaris, in the hypothetical structuro-functional transition between the dinocaridid frontal appendage and the pre-oral—arguably deutocerebral—appendage of euarthropods, we chose a phenetic approach and computed morphospace occupancy for the frontalmost appendages of 36 stem and crown taxa. Results show different levels of evolutionary decoupling between frontalmost appendage disparity and body plans. Variance is greatest in dinocaridids and “stem bivalved” arthropods, but these groups do not occupy the morphospace homogeneously. Rather, the diversity of frontalmost appendages in “stem bivalved” arthropods, distinct in its absence of clear clustering, is found to link the morphologies of “short great appendages,” chelicerae and antennules. This find fits the hypothesis of an increase in disparity of the deutocerebral appendage prior to its diversification in euarthropods, and possibly corresponds to its original time of development

  14. Composite Scaffolds for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Min Wang

    2006-01-01

    Full Text Available Biomaterial and scaffold development underpins the advancement of tissue engineering. Traditional scaffolds based on biodegradable polymers such as poly(lactic acid and poly(lactic acid-co-glycolic acid are weak and non-osteoconductive. For bone tissue engineering, polymer-based composite scaffolds containing bioceramics such as hydroxyapatite can be produced and used. The bioceramics can be either incorporated in the scaffolds as a dispersed secondary phase or form a thin coating on the pore surface of polymer scaffolds. This bioceramic phase renders the scaffolds bioactive and also strengthens the scaffolds. There are a number of methods that can be used to produce bioceramic-polymer composite scaffolds. This paper gives an overview of our efforts in developing composite scaffolds for bone tissue engineering.

  15. A green salt-leaching technique to produce sericin/PVA/glycerin scaffolds with distinguished characteristics for wound-dressing applications.

    Science.gov (United States)

    Aramwit, Pornanong; Ratanavaraporn, Juthamas; Ekgasit, Sanong; Tongsakul, Duangta; Bang, Nipaporn

    2015-05-01

    Sericin/PVA/glycerin scaffolds could be fabricated using the freeze-drying technique; they showed good physical and biological properties and can be applied as wound dressings. However, freeze-drying is an energy- and time-consuming process with a high associated cost. In this study, an alternative, solvent-free, energy- and time-saving, low-cost salt-leaching technique is introduced as a green technology to produce sericin/PVA/glycerin scaffolds. We found that sericin/PVA/glycerin scaffolds were successfully fabricated without any crosslinking using a salt-leaching technique. The salt-leached sericin/PVA/glycerin scaffolds had a porous structure with pore interconnectivity. The sericin in the salt-leached scaffolds had a crystallinity that was as high as that of the freeze-dried scaffolds. Compared to the freeze-dried scaffolds with the same composition, the salt-leached sericin/PVA/glycerin scaffolds has larger pores, a lower Young's modulus, and faster rates of biodegradation and sericin release. When cultured with L929 mouse fibroblast cells, a higher number of cells were found in the salt-leached scaffolds. Furthermore, the salt-leached scaffolds were less adhesive to the wound, which would reduce pain upon removal. Therefore, salt-leached sericin/PVA/glycerin scaffolds with distinguished characteristics were introduced as another choice of wound dressing, and their production process was simpler, more energy efficient, and saved time and money compared to the freeze-dried scaffolds.

  16. Scaffolding in Assisted Instruction

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available On-The-Job Training, developed as direct instruction, is one of the earliest forms of training. This method is still widely in use today because it requires only a person who knows how to do the task, and the tools the person uses to do the task. This paper is intended to be a study of the methods used in education in Knowledge Society, with more specific aspects in training the trainers; as a result of this approach, it promotes scaffolding in assisted instruction as a reflection of the digital age for the learning process. Training the trainers in old environment with default techniques and designing the learning process in assisted instruction, as an application of the Vygotskian concept of the zone of proximal development (ZPD to the area of computer literacy for the younger users, generate diversity in educational communities and requires standards for technology infrastructure, standards for the content, developed as a concepts map, and applications for personalized in-struction, based on ZPD theory.

  17. Decellularized Human Dental Pulp as a Scaffold for Regenerative Endodontics.

    Science.gov (United States)

    Song, J S; Takimoto, K; Jeon, M; Vadakekalam, J; Ruparel, N B; Diogenes, A

    2017-06-01

    Teeth undergo postnatal organogenesis relatively late in life and only complete full maturation a few years after the crown first erupts in the oral cavity. At this stage, development can be arrested if the tooth organ is damaged by either trauma or caries. Regenerative endodontic procedures (REPs) are a treatment alternative to conventional root canal treatment for immature teeth. These procedures rely on the transfer of apically positioned stem cells, including stem cells of the apical papilla (SCAP), into the root canal system. Although clinical success has been reported for these procedures, the predictability of expected outcomes and the organization of the newly formed tissues are affected by the lack of an available suitable scaffold that mimics the complexity of the dental pulp extracellular matrix (ECM). In this study, we evaluated 3 methods of decellularization of human dental pulp to be used as a potential autograft scaffold. Tooth slices of human healthy extracted third molars were decellularized by 3 different methods. One of the methods generated the maximum observed decellularization with minimal impact on the ECM composition and organization. Furthermore, recellularization of the scaffold supported the proliferation of SCAP throughout the scaffold with differentiation into odontoblast-like cells near the dentinal walls. Thus, this study reports that human dental pulp from healthy extracted teeth can be successfully decellularized, and the resulting scaffold supports the proliferation and differentiation of SCAP. The future application of this form of an autograft in REPs can fulfill a yet unmet need for a suitable scaffold, potentially improving clinical outcomes and ultimately promoting the survival and function of teeth with otherwise poor prognosis.

  18. Neuronal Networks on Nanocellulose Scaffolds.

    Science.gov (United States)

    Jonsson, Malin; Brackmann, Christian; Puchades, Maja; Brattås, Karoline; Ewing, Andrew; Gatenholm, Paul; Enejder, Annika

    2015-11-01

    Proliferation, integration, and neurite extension of PC12 cells, a widely used culture model for cholinergic neurons, were studied in nanocellulose scaffolds biosynthesized by Gluconacetobacter xylinus to allow a three-dimensional (3D) extension of neurites better mimicking neuronal networks in tissue. The interaction with control scaffolds was compared with cationized nanocellulose (trimethyl ammonium betahydroxy propyl [TMAHP] cellulose) to investigate the impact of surface charges on the cell interaction mechanisms. Furthermore, coatings with extracellular matrix proteins (collagen, fibronectin, and laminin) were investigated to determine the importance of integrin-mediated cell attachment. Cell proliferation was evaluated by a cellular proliferation assay, while cell integration and neurite propagation were studied by simultaneous label-free Coherent anti-Stokes Raman Scattering and second harmonic generation microscopy, providing 3D images of PC12 cells and arrangement of nanocellulose fibrils, respectively. Cell attachment and proliferation were enhanced by TMAHP modification, but not by protein coating. Protein coating instead promoted active interaction between the cells and the scaffold, hence lateral cell migration and integration. Irrespective of surface modification, deepest cell integration measured was one to two cell layers, whereas neurites have a capacity to integrate deeper than the cell bodies in the scaffold due to their fine dimensions and amoeba-like migration pattern. Neurites with lengths of >50 μm were observed, successfully connecting individual cells and cell clusters. In conclusion, TMAHP-modified nanocellulose scaffolds promote initial cellular scaffold adhesion, which combined with additional cell-scaffold treatments enables further formation of 3D neuronal networks.

  19. Intervertebral Disc Tissue Engineering with Natural Extracellular Matrix-Derived Biphasic Composite Scaffolds.

    Directory of Open Access Journals (Sweden)

    Baoshan Xu

    Full Text Available Tissue engineering has provided an alternative therapeutic possibility for degenerative disc diseases. However, we lack an ideal scaffold for IVD tissue engineering. The goal of this study is to fabricate a novel biomimetic biphasic scaffold for IVD tissue engineering and evaluate the feasibility of developing tissue-engineered IVD in vitro and in vivo. In present study we developed a novel integrated biphasic IVD scaffold using a simple freeze-drying and cross-linking technique of pig bone matrix gelatin (BMG for the outer annulus fibrosus (AF phase and pig acellular cartilage ECM (ACECM for the inner nucleus pulposus (NP phase. Histology and SEM results indicated no residual cells remaining in the scaffold that featured an interconnected porous microstructure (pore size of AF and NP phase 401.4 ± 13.1 μm and 231.6 ± 57.2 μm, respectively. PKH26-labeled AF and NP cells were seeded into the scaffold and cultured in vitro. SEM confirmed that seeded cells could anchor onto the scaffold. Live/dead staining showed that live cells (green fluorescence were distributed in the scaffold, with no dead cells (red fluorescence being found. The cell-scaffold constructs were implanted subcutaneously into nude mice and cultured for 6 weeks in vivo. IVD-like tissue formed in nude mice as confirmed by histology. Cells in hybrid constructs originated from PKH26-labeled cells, as confirmed by in vivo fluorescence imaging system. In conclusion, the study demonstrates the feasibility of developing a tissue-engineered IVD in vivo with a BMG- and ACECM-derived integrated AF-NP biphasic scaffold. As well, PKH26 fluorescent labeling with in vivo fluorescent imaging can be used to track cells and analyse cell--scaffold constructs in vivo.

  20. Metacognitive scaffolding in an innovative learning arrangement

    NARCIS (Netherlands)

    Molenaar, I.; Boxtel, C.A.M. van; Sleegers, P.J.C.

    2011-01-01

    This study examined the effects of metacognitive scaffolds on learning outcomes of collaborating students in an innovative learning arrangement. The triads were supported by computerized scaffolds, which were dynamically integrated into the learning process and took a structuring or problematizing

  1. Synthesis of the TACO scaffold as a new selectively deprotectable conformationally restricted triazacyclophane based scaffold

    NARCIS (Netherlands)

    Brouwer, Arwin J; van de Langemheen, Helmus; Ciaffoni, Adriano; Schilder, Kitty E; Liskamp, Rob M J

    2014-01-01

    The synthesis of a new triazacyclophane scaffold (TACO scaffold) containing three selectively deprotectable amines is described. The TACO scaffold is conformationally more constrained than our frequently used TAC scaffold, due to introduction of a substituent on the para position of the benzoic acid

  2. ScaffoldSeq: Software for characterization of directed evolution populations.

    Science.gov (United States)

    Woldring, Daniel R; Holec, Patrick V; Hackel, Benjamin J

    2016-07-01

    ScaffoldSeq is software designed for the numerous applications-including directed evolution analysis-in which a user generates a population of DNA sequences encoding for partially diverse proteins with related functions and would like to characterize the single site and pairwise amino acid frequencies across the population. A common scenario for enzyme maturation, antibody screening, and alternative scaffold engineering involves naïve and evolved populations that contain diversified regions, varying in both sequence and length, within a conserved framework. Analyzing the diversified regions of such populations is facilitated by high-throughput sequencing platforms; however, length variability within these regions (e.g., antibody CDRs) encumbers the alignment process. To overcome this challenge, the ScaffoldSeq algorithm takes advantage of conserved framework sequences to quickly identify diverse regions. Beyond this, unintended biases in sequence frequency are generated throughout the experimental workflow required to evolve and isolate clones of interest prior to DNA sequencing. ScaffoldSeq software uniquely handles this issue by providing tools to quantify and remove background sequences, cluster similar protein families, and dampen the impact of dominant clones. The software produces graphical and tabular summaries for each region of interest, allowing users to evaluate diversity in a site-specific manner as well as identify epistatic pairwise interactions. The code and detailed information are freely available at http://research.cems.umn.edu/hackel. Proteins 2016; 84:869-874. © 2016 Wiley Periodicals, Inc.

  3. Scaffold-free vascular tissue engineering using bioprinting.

    Science.gov (United States)

    Norotte, Cyrille; Marga, Francois S; Niklason, Laura E; Forgacs, Gabor

    2009-10-01

    Current limitations of exogenous scaffolds or extracellular matrix based materials have underlined the need for alternative tissue-engineering solutions. Scaffolds may elicit adverse host responses and interfere with direct cell-cell interaction, as well as assembly and alignment of cell-produced ECM. Thus, fabrication techniques for production of scaffold-free engineered tissue constructs have recently emerged. Here we report on a fully biological self-assembly approach, which we implement through a rapid prototyping bioprinting method for scaffold-free small diameter vascular reconstruction. Various vascular cell types, including smooth muscle cells and fibroblasts, were aggregated into discrete units, either multicellular spheroids or cylinders of controllable diameter (300-500 microm). These were printed layer-by-layer concomitantly with agarose rods, used here as a molding template. The post-printing fusion of the discrete units resulted in single- and double-layered small diameter vascular tubes (OD ranging from 0.9 to 2.5mm). A unique aspect of the method is the ability to engineer vessels of distinct shapes and hierarchical trees that combine tubes of distinct diameters. The technique is quick and easily scalable.

  4. Combined percutaneous balloon mitral valvuloplasty and left atrial appendage occlusion device implantation for rheumatic mitral stenosis and atrial fibrillation

    Energy Technology Data Exchange (ETDEWEB)

    Murdoch, Dale, E-mail: dale_murdoch@health.qld.gov.au [The Prince Charles Hospital, Brisbane (Australia); The University of Queensland, Brisbane (Australia); McAulay, Laura [The Prince Charles Hospital, Brisbane (Australia); Walters, Darren L. [The Prince Charles Hospital, Brisbane (Australia); The University of Queensland, Brisbane (Australia)

    2014-11-15

    Rheumatic heart disease is a common cause of cardiovascular morbidity and mortality worldwide, mostly in developing countries. Mitral stenosis and atrial fibrillation often coexist, related to both structural and inflammatory changes of the mitral valve and left atrium. Both predispose to left atrial thrombus formation, commonly involving the left atrial appendage. Thromboembolism can occur, with devastating consequences. We report the case of a 62 year old woman with rheumatic heart disease resulting in mitral stenosis and atrial fibrillation. Previous treatment with warfarin resulted in life-threatening gastrointestinal bleeding and she refused further anticoagulant therapy. A combined procedure was performed, including percutaneous balloon mitral valvuloplasty and left atrial appendage occlusion device implantation with the Atritech® Watchman® device. No thromboembolic or bleeding complications were encountered at one year follow-up. Long-term follow-up in a cohort of patients will be required to evaluate the safety and efficacy of this strategy.

  5. Molecular Recognition within Synaptic Scaffolds

    DEFF Research Database (Denmark)

    Erlendsson, Simon

    function. At the molecular level PICK1 contains both a BAR and a PDZ domain making it quite unique. Especially the specificity and promiscuity of the PICK1 PDZ domain seems to be more complicated than normally seen for PDZ domains. Also, the ability of PICK1 to form dimeric structures via its central BAR...... by the spatial architecture of the synapse itself. In this thesis, the molecular scaffolding mechanisms of PICK1 have been investigated in both isolated and near native conditions. Our findings have significantly benefitted the general understanding of how PICK1 and PDZ domain scaffolding works. In the first......-inhibitory mechanism of PICK1 and allows the N-BAR domains or the PDZ domains themselves to cluster and shape membranes. Finally, we utilized our in-solution structural knowledge to investigate the scaffolding events in context of a native cell membrane. We initially showed that we were able to qualitatively assess...

  6. Presence of accessory left atrial appendage/diverticula in a population with atrial fibrillation compared with those in sinus rhythm: a retrospective review.

    Science.gov (United States)

    Troupis, John; Crossett, Marcus; Scneider-Kolsky, Michal; Nandurkar, Dee

    2012-02-01

    Accessory left atrial appendages and atrial diverticula have an incidence of 10-27%. Their association with atrial fibrillation needs to be confirmed. This study determined the prevalence, number, size, location and morphology of accessory left atrial appendages/atrial diverticula in patients with atrial fibrillation compared with those in sinus rhythm. A retrospective analysis of 47 consecutive patients with atrial fibrillation who underwent 320 multidetector Coronary CT angiography (CCTA) was performed. A random group of 47 CCTA patients with sinus rhythm formed the control group. The presence, number, size, location and morphology of accessory left atrial appendages and atrial diverticula in each group were analysed. Twenty one patients had a total of 25 accessory left atrial appendages and atrial diverticula in the atrial fibrillation group and 22 patients had a total of 24 accessory left atrial appendages and atrial diverticula in the sinus rhythm group. Twenty-one atrial diverticula were identified in 19 patients in the atrial fibrillation group and 19 atrial diverticula in 17 patients in the sinus rhythm group. The mean length and width of accessory left atrial appendage was 6.9 and 4.7 mm, respectively in the atrial fibrillation group and 12 and 4.6 mm, respectively, in the sinus rhythm group, P = ns (not significant). The mean length and width of atrial diverticulum was 4.7 and 3.6 mm, respectively in the atrial fibrillation group and 6.2 and 5 mm, respectively in the sinus rhythm group (P = ns). Eighty-four % and 96% of the accessory left atrial appendages/atrial diverticula in the atrial fibrillation and sinus rhythm groups were located along the right anterosuperior left atrial wall. Accessory left atrial appendages and atrial diverticula are common structures with similar prevalence in patients with atrial fibrillation and sinus rhythm.

  7. Setal morphology of the grooming appendages of Macrobrachium rosenbergii (Crustacea: Decapoda: Caridea: Palaemonidae) and review of decapod setal classification.

    Science.gov (United States)

    Wortham, Jennifer L; Vanmaurik, Lauren N; Wayne Price, W

    2014-06-01

    Setae are vital in grooming activities and aiding in the removal of epibionts and sedimentary fouling from the body surfaces of decapod crustaceans. Thus, the setal structures and their arrangement on the grooming appendages and sensory structures of the commercially important shrimp, Macrobrachium rosenbergii, were examined using scanning electron microscopy. Macrobrachium rosenbergii is extensively grown in aquaculture and exhibits unique male morphological forms, termed morphotypes. The three male morphotypes are termed blue-clawed males, orange-clawed males, and small-clawed or undifferentiated males and all three differ in their dominance, behavior, body morphology, and reproductive success. Seven setal types, two of which have never been described in the literature, are identified on the grooming appendages (third maxillipeds, first, second, and fifth pereopods) and antennae: simple, serrate, serrulate, spiniform, pappose, crinoid, and spinulate. The latter two setae are newly identified. Certain setal types, such as serrate and serrulate setae were located and associated with specific grooming appendages such as the first pereopods. The types of setae on the grooming appendages varied among females and male morphotypes and the novel setal types (crinoid and spinulate) were found only on two of the male morphotypes. A literature review of terminology related to the structure of setae and setal types in decapod crustaceans is offered as the usage of various terms is ambiguous and conflicting in the literature. The intention of this review is to provide future authors with a comprehensive collection of terms and images that can be used to describe various aspects of setal morphology in decapods.

  8. Systematic Prediction of Scaffold Proteins Reveals New Design Principles in Scaffold-Mediated Signal Transduction

    Science.gov (United States)

    Hu, Jianfei; Neiswinger, Johnathan; Zhang, Jin; Zhu, Heng; Qian, Jiang

    2015-01-01

    Scaffold proteins play a crucial role in facilitating signal transduction in eukaryotes by bringing together multiple signaling components. In this study, we performed a systematic analysis of scaffold proteins in signal transduction by integrating protein-protein interaction and kinase-substrate relationship networks. We predicted 212 scaffold proteins that are involved in 605 distinct signaling pathways. The computational prediction was validated using a protein microarray-based approach. The predicted scaffold proteins showed several interesting characteristics, as we expected from the functionality of scaffold proteins. We found that the scaffold proteins are likely to interact with each other, which is consistent with previous finding that scaffold proteins tend to form homodimers and heterodimers. Interestingly, a single scaffold protein can be involved in multiple signaling pathways by interacting with other scaffold protein partners. Furthermore, we propose two possible regulatory mechanisms by which the activity of scaffold proteins is coordinated with their associated pathways through phosphorylation process. PMID:26393507

  9. Systematic Prediction of Scaffold Proteins Reveals New Design Principles in Scaffold-Mediated Signal Transduction.

    Directory of Open Access Journals (Sweden)

    Jianfei Hu

    Full Text Available Scaffold proteins play a crucial role in facilitating signal transduction in eukaryotes by bringing together multiple signaling components. In this study, we performed a systematic analysis of scaffold proteins in signal transduction by integrating protein-protein interaction and kinase-substrate relationship networks. We predicted 212 scaffold proteins that are involved in 605 distinct signaling pathways. The computational prediction was validated using a protein microarray-based approach. The predicted scaffold proteins showed several interesting characteristics, as we expected from the functionality of scaffold proteins. We found that the scaffold proteins are likely to interact with each other, which is consistent with previous finding that scaffold proteins tend to form homodimers and heterodimers. Interestingly, a single scaffold protein can be involved in multiple signaling pathways by interacting with other scaffold protein partners. Furthermore, we propose two possible regulatory mechanisms by which the activity of scaffold proteins is coordinated with their associated pathways through phosphorylation process.

  10. Biomaterials & scaffolds for tissue engineering

    Directory of Open Access Journals (Sweden)

    Fergal J. O'Brien

    2011-03-01

    Full Text Available Every day thousands of surgical procedures are performed to replace or repair tissue that has been damaged through disease or trauma. The developing field of tissue engineering (TE aims to regenerate damaged tissues by combining cells from the body with highly porous scaffold biomaterials, which act as templates for tissue regeneration, to guide the growth of new tissue. This article describes the functional requirements, and types, of materials used in developing state of the art of scaffolds for tissue engineering applications. Furthermore, it describes the challenges and where future research and direction is required in this rapidly advancing field.

  11. Functional analyses in the milkweed bug Oncopeltus fasciatus (Hemiptera) support a role for Wnt signaling in body segmentation but not appendage development.

    Science.gov (United States)

    Angelini, David R; Kaufman, Thomas C

    2005-07-15

    Specification of the proximal-distal (PD) axis of insect appendages is best understood in Drosophila melanogaster, where conserved signaling molecules encoded by the genes decapentaplegic (dpp) and wingless (wg) play key roles. However, the development of appendages from imaginal discs as in Drosophila is a derived state, while more basal insects produce appendages from embryonic limb buds. Therefore, the universality of the Drosophila limb PD axis specification mechanism has been debated since dpp expression in more basal insect species differs dramatically from Drosophila. Here, we test the function of Wnt signaling in the development of the milkweed bug Oncopeltus fasciatus, a species with the basal state of appendage development from limb buds. RNA interference of wg and pangolin (pan) produce defects in the germband and eyes, but not in the appendages. Distal-less and dachshund, two genes regulated by Wg signaling in Drosophila and expressed in specific PD domains along the limbs of both species, are expressed normally in the limbs of pan-depleted Oncopeltus embryos. Despite these apparently paradoxical results, Armadillo protein, the transducer of Wnt signaling, does not accumulate properly in the nuclei of cells in the legs of pan-depleted embryos. In contrast, engrailed RNAi in Oncopeltus produces cuticular and appendage defects similar to Drosophila. Therefore, our data suggest that Wg signaling is functionally conserved in the development of the germband, while it is not essential in the specification of the limb PD axis in Oncopeltus and perhaps basal insects.

  12. Differential gene expression during atrial structural remodeling in human left and right atrial appendages in atrial fibrillation

    Institute of Scientific and Technical Information of China (English)

    Hui Zhu; Wei Zhang; Ming Zhong; Gong Zhang; Yun Zhang

    2011-01-01

    Extracellular matrix (ECM) remodeling increases the vulnerability to atrial fibrillation (AF). Some gene expressions are crucial for the metabolism of ECM. The left atrium plays an important role in maintaining AF.However, most studies investigated only the right atrial tissue. We therefore chose human tissue samples from both the left and right atrial to detect the different gene expressions during structural remodeling in AF. The atrial appendages tissue samples from 24 patients with chronic AF and 12 patients with sinus rhythm were obtained when they were undergoing mitral/aortic valve replacement operation. The mRNA levels of matrix metalloproteinases-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), disintegrin, metalloproteases-15, and integrins β1 were determined by reverse transcriptionpolymerase chain reaction (RT-PCR). in AF group, the level of MMP-9 in left atrial appendage (LAA) was increased (P<0.001), while integrin β1 level was decreased (P< 0.05) compared with those expressed in right atrial appendage (RAA) tissue. The levels of disintegrin, metalloproteinases-15, and TIMP-1 genes in the LAA and RAA had no significant differences. The results demonstrated that the gene expressions in the LAA and RAA are different during AF, which implied that the mechanism of atrial structural remodeling in AF is due to multiple sources and is complicated.

  13. Polyurethane scaffold with in situ swelling capacity for nucleus pulposus replacement.

    Science.gov (United States)

    Li, Zhen; Lang, Gernot; Chen, Xu; Sacks, Hagit; Mantzur, Carmit; Tropp, Udi; Mader, Kerstin T; Smallwood, Thomas C; Sammon, Chris; Richards, R Geoff; Alini, Mauro; Grad, Sibylle

    2016-04-01

    Nucleus pulposus (NP) replacement offers a minimally invasive alternative to spinal fusion or total disc replacement for the treatment of intervertebral disc (IVD) degeneration. This study aimed to develop a cytocompatible NP replacement material, which is feasible for non-invasive delivery and tunable design, and allows immediate mechanical restoration of the IVD. A bi-phasic polyurethane scaffold was fabricated consisting of a core material with rapid swelling property and a flexible electrospun envelope. The scaffold was assessed in a bovine whole IVD organ culture model under dynamic load for 14 days. Nucleotomy was achieved by incision through the endplate without damaging the annulus fibrosus. After implantation of the scaffold and in situ swelling, the dynamic compressive stiffness and disc height were restored immediately. The scaffold also showed favorable cytocompatibility for native disc cells. Implantation of the scaffold in a partially nucleotomized IVD down-regulated catabolic gene expression, increased proteoglycan and type II collagen intensity and decreased type I collagen intensity in remaining NP tissue, indicating potential to retard degeneration and preserve the IVD cell phenotype. The scaffold can be delivered in a minimally invasive manner, and the geometry of the scaffold post-hydration is tunable by adjusting the core material, which allows individualized design.

  14. Fabrication of Metallic Biomedical Scaffolds with the Space Holder Method: A Review

    Directory of Open Access Journals (Sweden)

    Budi Arifvianto

    2014-05-01

    Full Text Available Bone tissue engineering has been increasingly studied as an alternative approach to bone defect reconstruction. In this approach, new bone cells are stimulated to grow and heal the defect with the aid of a scaffold that serves as a medium for bone cell formation and growth. Scaffolds made of metallic materials have preferably been chosen for bone tissue engineering applications where load-bearing capacities are required, considering the superior mechanical properties possessed by this type of materials to those of polymeric and ceramic materials. The space holder method has been recognized as one of the viable methods for the fabrication of metallic biomedical scaffolds. In this method, temporary powder particles, namely space holder, are devised as a pore former for scaffolds. In general, the whole scaffold fabrication process with the space holder method can be divided into four main steps: (i mixing of metal matrix powder and space-holding particles; (ii compaction of granular materials; (iii removal of space-holding particles; (iv sintering of porous scaffold preform. In this review, detailed procedures in each of these steps are presented. Technical challenges encountered during scaffold fabrication with this specific method are addressed. In conclusion, strategies are yet to be developed to address problematic issues raised, such as powder segregation, pore inhomogeneity, distortion of pore sizes and shape, uncontrolled shrinkage and contamination.

  15. In vitro and in vivo Characterization of Homogeneous Chitosan-based Composite Scaffolds

    Institute of Scientific and Technical Information of China (English)

    LI Hong; ZHOU Changren; ZHU Minying; TIAN Jinhuan; RONG Jianhua

    2012-01-01

    With a homogeneous distribution of hydroxyapatite (HAP) crystals in polymer matrix,composite scaffolds chitosan/HAP and chitosan/collagen/HAP were fabricated in the study.XRD,SEM and EDX were used to characterize their components and structure,in vitro cell culture and in vivo animal tests were used to evaluate their biocompatibility.HAP crystals with rod-like shape embeded in chitosan scaffold,while HAP fine-granules bond with collagen/chitosan scaffold compactly.A homogenous distribution of Ca and P elements both in chitosan/HAP scaffold and chitosan/collagen/HAP scaffold was defined by EDX pattern.The presence of collagen brought a more homogenous distribution of HAP due to its higher ability to induce HAP precipitation.The results of in vitro cell culture showed that the composite's biocompatibility was enhanced by the homogenous distribution of HAP.In vivo animal studies showed that the in vivo biodegradation was effectively improved by the addition of HAP and collagen,and was less influenced by the homogeneous distribution of HAP when compared with a concentrated distribution one.The composite scaffolds with a homogeneous HAP distribution would be excellent alternative scaffolds for bone tissue engineering.

  16. Alternative energies; Energies alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Bonal, J.; Rossetti, P

    2007-07-01

    The earth took millions years to made the petroleum, the gas the coal and the uranium. Only a few centuries will be needed to exhaust these fossil fuels and some years to reach expensive prices. Will the wold continue on this way of energy compulsive consumption? The renewable energies and some citizen attitudes are sufficient to break this spiral. This book proposes to discuss these alternative energies. It shows that this attitude must be supported by the government. It takes stock on the more recent information concerning the renewable energies. it develops three main points: the electricity storage, the housing and the transports. (A.L.B.)

  17. Impact of scaffold micro and macro architecture on Schwann cell proliferation under dynamic conditions in a rotating wall vessel bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Valmikinathan, Chandra M.; Hoffman, John [Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030 (United States); Yu, Xiaojun, E-mail: xyu@stevens.edu [Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030 (United States)

    2011-01-01

    Over the last decade tissue engineering has emerged as a powerful alternative to regenerate lost tissues owing to trauma or tumor. Evidence shows that Schwann cell containing scaffolds have improved performance in vivo as compared to scaffolds that depend on cellularization post implantation. However, owing to limited supply of cells from the patients themselves, several approaches have been taken to enhance cell proliferation rates to produce complete and uniform cellularization of scaffolds. The most common approach is the application of a bioreactor to enhance cell proliferation rate and therefore reduce the time needed to obtain sufficiently significant number of glial cells, prior to implantation. In this study, we show the application of a rotating wall bioreactor system for studying Schwann cell proliferation on nanofibrous spiral shaped scaffolds, prepared by solvent casting and salt leaching techniques. The scaffolds were fabricated from polycaprolactone (PCL), which has ideal mechanical properties and upon degradation does not produce acidic byproducts. The spiral scaffolds were coated with aligned or random nanofibers, produced by electrospinning, to provide a substrate that mimics the native extracellular matrix and the essential contact guidance cues. At the 4 day time point, an enhanced rate of cell proliferation was observed on the open structured nanofibrous spiral scaffolds in a rotating wall bioreactor, as compared to static culture conditions. However, the cell proliferation rate on the other contemporary scaffolds architectures such as the tubular and cylindrical scaffolds show reduced cell proliferation in the bioreactor as compared to static conditions, at the same time point. Moreover, the rotating wall bioreactor does not alter the orientation or the phenotype of the Schwann cells on the aligned nanofiber containing scaffolds, wherein, the cells remain aligned along the length of the scaffolds. Therefore, these open structured spiral

  18. Cardiac procedures to prevent stroke: patent foramen ovale closure/left atrial appendage occlusion.

    Science.gov (United States)

    Freixa, Xavier; Arzamendi, Dabit; Tzikas, Apostolos; Noble, Stephane; Basmadjian, Arsene; Garceau, Patrick; Ibrahim, Réda

    2014-01-01

    Stroke is a major contributor to population morbidity and mortality. Cardiac thromboembolic sources are an important potential cause of stroke. Left atrial appendage (LAA) thromboembolism in association with atrial fibrillation is a major contributor to stroke occurrence, particularly in elderly individuals. Patent foramen ovale (PFO) acts as a potential conduit from the right-sided circulation to the brain, and has been suggested to be an important factor in cryptogenic stroke in the young patients. Advances in interventional cardiology have made it possible to deal with these potential stroke sources (LAA and PFO), but the available methods have intrinsic limitations that must be recognized. Furthermore, the potential value of LAA and PFO closure depends on our ability to identify when the target structure is importantly involved in stroke risk; this is particularly challenging for PFO. This article addresses the clinical use of PFO and LAA closure in stroke prevention. We discuss technical aspects of closure devices and methods, questions of patient selection, and clinical trials evidence. We conclude that for PFO closure, the clinical trials evidence is thus far negative in the broad cryptogenic stroke population, but closure might nevertheless be indicated for selected high-risk patients. LAA closure has an acceptable balance between safety and efficacy for atrial fibrillation patients with high stroke risk and important contraindications to oral anticoagulation. Much more work needs to be done to optimize the devices and techniques, and better define patient selection for these potentially valuable procedures.

  19. Current problems concerning parasitology and mycology with regard to diseases of the skin and its appendages.

    Science.gov (United States)

    Błaszkowska, Joanna; Wójcik, Anna

    2012-01-01

    Current issues concerning Parasitology and Mycology with regard to diseases of the skin and its appendages are presented. Aspects of diagnostics, clinical picture and therapy of skin and nail mycoses, as well as difficulties in the diagnosis and treatment of both native parasitoses (toxoplasmosis) and imported human tropical parasitoses (malaria, filariosis) have been emphasised. The clinical importance of environmental mould fungi in nosocomial infections and fungal meningitis, as well as selected properties of fungi isolated from patients with head and neck neoplasms treated by radiotherapy are discussed. Other mycological topics include the characteristics of newly-synthesized thiosemicarbazides and thiadiazoles as potential drugs against toxoplasmosis and their biological activity against Toxoplasma gondii tachyzoites, selected molecular mechanisms of resistance to azoles, Candida albicans strains and a new tool (barcoding DNA) for describing the biodiversity of potential allergenic molds. The importance of environmental factors in pathogenesis of mycoses and parasitoses is noted. The characteristics of pathogenic fungi isolated from natural ponds in Bialystok and potentially pathogenic yeast-like fungi isolated from children's recreation areas in Lodz are presented. The ongoing problem of anthropozoonoses is considered, as are the roles of stray cats and dogs in contaminating soil with the developing forms of intestinal parasites. The characteristics of the human microbiome, including population composition, activity and their importance in normal human physiology, are presented, as are the major goals of the Human Microbiome Project initiated by National Institutes of Health (NIH).

  20. An early Late Triassic long-necked reptile with a bony pectoral shield and gracile appendages

    Directory of Open Access Journals (Sweden)

    Jerzy Dzik

    2016-12-01

    Full Text Available Several partially articulated specimens and numerous isolated bones of Ozimek volans gen. et sp. nov., from the late Carnian lacustrine deposits exposed at Krasiejów in southern Poland, enable a reconstruction of most of the skeleton. The unique character of the animal is its enlarged plate-like coracoids presumably fused with sterna. Other aspects of the skeleton seem to be comparable to those of the only known specimen of Sharovipteryx mirabilis from the latest Middle Triassic of Kyrgyzstan, which supports interpretation of both forms as protorosaurians. One may expect that the pectoral girdle of S. mirabilis, probably covered by the rock matrix in its only specimen, was similar to that of O. volans gen. et sp. nov. The Krasiejów material shows sharp teeth, low crescent scapula, three sacrals in a generalized pelvis (two of the sacrals being in contact with the ilium and curved robust metatarsal of the fifth digit in the pes, which are unknown in Sharovipteryx. Other traits are plesiomorphic and, except for the pelvic girdle and extreme elongation of appendages, do not allow to identify any close connection of the sharovipterygids within the Triassic protorosaurians.

  1. EPIDEMIOLOGIC, CLINICO-MYCOLOGICAL ASPECTS OF FUNGAL INFECTIONS OF SKIN AND ITS APPENDAGES

    Directory of Open Access Journals (Sweden)

    Sheikh

    2014-04-01

    Full Text Available : BACKGROUND: The incidence of fungal infections is increasing at an alarming rate, presenting an enormous challenge to healthcare professionals. The prevalence of fungal infections seems to vary across the world because of various socioeconomic and cultural factors. AIM: This study was undertaken to analyze the epidemiological, clinical and mycological features of fungal infections of skin and its appendages. SETTINGS AND DESIGN: Over a period of 1 year (Jan 2010 to Jan 2011 Samples were collected from 402 clinically suspected cases of fungal infections attending outpatient dermatology department of a tertiary care hospital & medical college Kashmir. MATERIAL AND METHODS: Clinical samples (Skin, Hair and Nail from 402 clinically suspected cases were included in the study. All specimens were subjected to KOH examination and culture. Germ tube tests were performed on all growths identified as yeasts. RESULTS: 298 (74% samples showed evidence of fungal elements on direct microscopy, out of which 183 (61.40% turned out to be positive on culture. The most common dermatophyte isolated from different clinical samples were Trichophyton rubrum followed by Trichophyton mantagrophyte. CONCLUSION: The traditional methods of diagnosing fungal infections are still the best and important tool of diagnosis for the fungal infections in our setting. More studies are required in this part of the country.

  2. “High-Throughput” Evaluation of Polymer-Supported Triazolic Appendages for Metallic Cations Extraction

    Directory of Open Access Journals (Sweden)

    Riadh Slimi

    2015-03-01

    Full Text Available The aim of this work was to find and use a low-cost high-throughput method for a quick primary evaluation of several metal extraction by substituted piperazines appendages as chelatants grafted onto Merrifield polymer using click-chemistry by the copper (I-catalyzed Huisgen’s reaction (CuAAC The polymers were tested for their efficiency to remove various metal ions from neutral aqueous solutions (13 cations studied: Li+, Na+, K+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Cd2+, Ba2+, Ce3+, Hg+ and Pb2+ using the simple conductimetric measurement method. The polymers were found to extract all metals with low efficiencies ≤40%, except for Fe3+ and Hg+, and sometimes Pb2+. Some polymers exhibited a selectively for K+, Cd2+ and Ba2+, with good efficiencies. The values obtained here using less polymer, and a faster method, are in fair correspondence (average difference ±16% with another published evaluation by atomic absorption spectroscopy (AAS.

  3. Age-related changes in morphology of left atrial appendage in patients with atrial fibrillation.

    Science.gov (United States)

    Hirata, Yukina; Kusunose, Kenya; Yamada, Hirotsugu; Shimizu, Rikuto; Torii, Yuta; Nishio, Susumu; Saijo, Yoshihito; Takao, Shoichiro; Soeki, Takeshi; Sata, Masataka

    2017-08-14

    The purpose of this study was to evaluate the relationship between age and frequency of left atrial appendage (LAA) morphology in patients with atrial fibrillation (AF) compared with sinus rhythm (SR). We enrolled 145 AF patients, and 199 SR patients for the control group without any cardiovascular disease. LAA volume index (LAAVi) and morphology were assessed by electrocardiogram-gated computed tomography angiography. LAA morphology was classified into "chicken wing" or "non-chicken wing" according to the previously described classification. There was no significant trend in frequency of non-chicken wing morphology among ages in the SR group (p = 0.36 for trend), whereas the frequency was negatively related to age in the AF group (p = 0.002 for trend). In multivariable logistic regression, age > 65 (odds ratio [OR] 0.42, p = 0.002) and duration of AF (OR 0.53, p = 0.010) and LAAVi (OR 0.62, p = 0.017) were independent factors of non-chicken wing LAA morphology in the AF group. LAA morphology is affected by age, especially in patients with AF. When we utilize non-chicken wing LAA morphology as a stroke risk factor in patients with AF, we should pay attention to their age.

  4. Velocity encoded cardiovascular magnetic resonance to assess left atrial appendage emptying

    Directory of Open Access Journals (Sweden)

    Muellerleile Kai

    2012-06-01

    Full Text Available Abstract Background The presence of impaired left atrial appendage (LAA function identifies patients who are prone to thrombus formation in the LAA and therefore being at high risk for subsequent cardioembolic stroke. LAA function is typically assessed by measurements of LAA emptying velocities using transesophageal echocardiography (TEE in clinical routine. This study aimed at evaluating the feasibility of assessing LAA emptying by velocity encoded (VENC cardiovascular magnetic resonance (CMR. Methods This study included 30 patients with sinus rhythm (n = 18 or atrial fibrillation (n = 12. VENC-CMR velocity measurements were performed perpendicular to the orifice of the LAA. Peak velocities were measured of passive diastolic LAA emptying (e-wave in all patients. Peak velocities of active, late-diastolic LAA emptying (a-wave were assessed in patients with sinus rhythm. Correlation and agreement was analyzed between VENC-CMR and TEE measurements of e- and a-wave peak velocities. Results A significant correlation and good agreement was found between VENC-CMR and TEE measurements of maximal e-wave velocities (r = 0.61, P  Conclusions The assessment of active and passive LAA emptying by VENC-CMR is feasible. Further evaluation is required of potential future clinical applications such as risk stratification for cardioembolic stroke.

  5. PROPERTIES OF FOREST SEED SAMARA, WITHOUT PTERYGOID APPENDAGES, LEGUMES AND WITHOUT PERICARP

    Directory of Open Access Journals (Sweden)

    Sinelnikov A. V.

    2015-02-01

    Full Text Available Properties of forest seeds are the basic and initial data for substantiate technology and technical means constructions, to separate the seeds from the samaras and extraction them from the legumes, and also to substantiate constructive, technological parameters and operating modes of seed-cleaning machines. So far, there are not enough full information about the technological and mechanical properties of forest seeds, this makes it difficult substantiation and developing new technologies and technical means, in particular, to separate the seeds from samaras hardwoods and extracting legumes from the leguminous trees. The article presents the results of studies of technological and mechanical properties of forest seeds with samara and without pterygoid appendages: Norway maple, ash and elm ordinary, as well as legumes: honey locust, white acacia, acacia yellow and pure seed. Were studied: weight of 1000 seeds, volume weight, mass and volume coefficients, angle of repose, the coefficient of static friction and the coefficient of dynamic friction of the various working surfaces, holding strength samaras to forest seeds and strength of legumes pods. The data obtained are used for substantiate technology and technical means constructions, to separate the seeds from the samaras and extraction them from the pericarp

  6. The regeneration blastema of lizards: an amniote model for the study of appendage replacement.

    Science.gov (United States)

    Gilbert, E A B; Delorme, S L; Vickaryous, M K

    2015-04-01

    Although amniotes (reptiles, including birds, and mammals) are capable of replacing certain tissues, complete appendage regeneration is rare. Perhaps the most striking example is the lizard tail. Tail loss initiates a spontaneous epimorphic (blastema-mediated) regenerative program, resulting in a fully functional but structurally non-identical replacement. Here we review lizard tail regeneration with a particular focus on the blastema. In many lizards, the original tail has evolved a series of fracture planes, anatomical modifications that permit the tail to be self-detached or autotomized. Following tail loss, the wound site is covered by a specialized wound epithelium under which the blastema develops. An outgrowth of the spinal cord, the ependymal tube, plays a key role in governing growth (and likely patterning) of the regenerate tail. In some species (e.g., geckos), the blastema forms as an apical aggregation of proliferating cells, similar to that of urodeles and teleosts. For other species (e.g., anoles) the identification of a proliferative blastema is less obvious, suggesting an unexpected diversity in regenerative mechanisms among tail-regenerating lizards.

  7. Cardiac Plug I and Amulet Devices: Left Atrial Appendage Closure for Stroke Prophylaxis in Atrial Fibrillation.

    Science.gov (United States)

    Parashar, Akhil; Tuzcu, E Murat; Kapadia, Samir R

    2015-01-01

    Percutaneous left atrial appendage (LAA) occlusion has emerged as an exciting and effective modality for stroke prophylaxis in patients with non-valvular atrial fibrillation who are deemed too high risk for anticoagulation with warfarin or newer anticoagulants. The Amplatzer devices have been used in LAA occlusion for more than a decade, starting with off label use of an atrial septal occluder device for LAA occlusion. This was followed by introduction of a dedicated Amplatzer cardiac plug (ACP) 1 for LAA occlusion, and more recently, the second generation Amulet device, with reported better stability enhancing features, has been introduced. Both these devices are widely used outside the United States, however in the US only the WATCHMAN device has been FDA approved. Unlike the WATCHMAN device, where the evidence is continuously building as the data from two pivotal randomized controlled trials are emerging, most of the evidence for ACP devices is from pooled multicenter registry data. In this article, we review the device design, implantation techniques and the most recently published evidence for both the Amplatzer cardiac plug 1 and the newer Amulet device. Our goal is to summarize the most recent literature and discuss the current role of the Amplatzer devices in the exciting and rapidly growing field of percutaneous LAA occlusion.

  8. Percutaneous left atrial appendage closure: procedural techniques and outcomes.

    Science.gov (United States)

    Saw, Jacqueline; Lempereur, Mathieu

    2014-11-01

    Percutaneous left atrial appendage closure technology for stroke prevention in patients with atrial fibrillation has significantly advanced in the past 2 decades. Several devices are under clinical investigation, and a few have already received Conformité Européene (CE)-mark approval and are available in many countries. The WATCHMAN device (Boston Scientific, Natick, Massachusetts) has the most supportive data and is under evaluation by the U.S. Food and Drug Administration for warfarin-eligible patients. The Amplatzer Cardiac Plug (St. Jude Medical, Plymouth, Minnesota) has a large real-world experience over the past 5 years, and a randomized trial comparing Amplatzer Cardiac Plug with the WATCHMAN device is anticipated in the near future. The Lariat procedure (SentreHEART Inc., Redwood City, California) has also gained interest lately, but early studies were concerning for high rates of serious pericardial effusion and major bleeding. The current real-world experience predominantly involves patients who are not long-term anticoagulation candidates or who are perceived to have high bleeding risks. This pattern of practice is expected to change when the U.S. Food and Drug Administration approves the WATCHMAN device for warfarin-eligible patients. This paper reviews in depth the procedural techniques, safety, and outcomes of the current leading devices. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  9. Interphotoreceptor matrix-poly(ϵ-caprolactone composite scaffolds for human photoreceptor differentiation

    Directory of Open Access Journals (Sweden)

    Petr Baranov

    2014-10-01

    Full Text Available Tissue engineering has been widely applied in different areas of regenerative medicine, including retinal regeneration. Typically, artificial biopolymers require additional surface modification (e.g. with arginine–glycine–aspartate-containing peptides or adsorption of protein, such as fibronectin, before cell seeding. Here, we describe an alternative approach for scaffold design: the manufacture of hybrid interphotoreceptor matrix-poly (ϵ-caprolactone scaffolds, in which the insoluble extracellular matrix of the retina is incorporated into a biodegradable polymer well suited for transplantation. The incorporation of interphotoreceptor matrix did not change the topography of polycaprolactone film, although it led to a slight increase in hydrophilic properties (water contact angle measurements. This hybrid scaffold provided sufficient stimuli for human retinal progenitor cell adhesion and inhibited proliferation, leading to differentiation toward photoreceptor cells (expression of Crx, Nrl, rhodopsin, ROM1. This scaffold may be used for transplantation of retinal progenitor cells and their progeny to treat retinal degenerative disorders.

  10. Left Atrial Appendage Isolation in Patients With Longstanding Persistent AF Undergoing Catheter Ablation: BELIEF Trial.

    Science.gov (United States)

    Di Biase, Luigi; Burkhardt, J David; Mohanty, Prasant; Mohanty, Sanghamitra; Sanchez, Javier E; Trivedi, Chintan; Güneş, Mahmut; Gökoğlan, Yalçın; Gianni, Carola; Horton, Rodney P; Themistoclakis, Sakis; Gallinghouse, G Joseph; Bailey, Shane; Zagrodzky, Jason D; Hongo, Richard H; Beheiry, Salwa; Santangeli, Pasquale; Casella, Michela; Dello Russo, Antonio; Al-Ahmad, Amin; Hranitzky, Patrick; Lakkireddy, Dhanunjaya; Tondo, Claudio; Natale, Andrea

    2016-11-01

    Longstanding persistent (LSP) atrial fibrillation (AF) is the most challenging type of AF. In addition to pulmonary vein isolation, substrate modification and triggers ablation have been reported to improve freedom from AF in patients with LSPAF. This study sought to assess whether the empirical electrical isolation of the left atrial appendage (LAA) could improve success at follow-up. This was an open-label, randomized study assessing the effectiveness of empirical electrical left atrial appendage isolation for the treatment of LSPAF. Patients were randomly assigned to undergo empirical electrical left atrial appendage isolation along with extensive ablation (group 1; n = 85) or extensive ablation alone (group 2; n = 88). Recurrence of atrial arrhythmias was the primary endpoint. Secondary endpoints included cardiac-related hospitalization, all-cause mortality, and stroke at follow-up. Major clinical characteristics were not different between the 2 groups. At 12-month follow-up, 48 (56%) patients in group 1 and 25 (28%) in group 2 were recurrence free after a single procedure (unadjusted hazard ratio [HR] for recurrence with standard ablation: 1.92; 95% confidence interval [CI]: 1.3 to 2.9; log-rank p = 0.001). After adjusting for age, sex, and left atrial size, standard ablation was predictive of recurrence (HR: 2.22; 95% CI: 1.29 to 3.81; p = 0.004). During repeat procedures, empirical electrical left atrial appendage isolation was performed in all patients. After an average of 1.3 procedures, cumulative success at 24-month follow-up was reported in 65 (76%) in group 1 and in 49 (56%) in group 2 (unadjusted HR: 2.24; 95% CI: 1.3 to 3.8; log-rank p = 0.003). This randomized study showed that both after a single procedure and after redo procedures in patients with LSPAF, empirical electrical isolation of the LAA improved long-term freedom from atrial arrhythmias without increasing complications. (Effect of Empirical Left Atrial Appendage Isolation on Long

  11. Alternative additives; Alternative additiver

    Energy Technology Data Exchange (ETDEWEB)

    2007-08-15

    In this project a number of industrial and agricultural waste products have been characterised and evaluated in terms of alkali-getter performance. The intended use is for biomass-fired power stations aiming at reducing corrosion or slagging related problems. The following products have been obtained, characterised and evaluated: 1) Brewery draff 2) Danish de-gassed manure 3) Paper sludge 4) Moulding sand 5) Spent bleaching earth 6) Anorthosite 7) Sand 8) Clay-sludge. Most of the above alternative additive candidates are deemed unsuitable due to insufficient chemical effect and/or expensive requirements for pre-treatment (such as drying and transportation). 3 products were selected for full-scale testing: de-gassed manure, spent bleaching earth and clay slugde. The full scale tests were undertaken at the biomass-fired power stations in Koege, Slagelse and Ensted. Spent bleaching earth (SBE) and clay sludge were the only tested additive candidates that had a proven ability to react with KCl, to thereby reduce Cl-concentrations in deposits, and reduce the deposit flux to superheater tubes. Their performance was shown to nearly as good as commercial additives. De-gassed manure, however, did not evaluate positively due to inhibiting effects of Ca in the manure. Furthermore, de-gassed manure has a high concentration of heavy metals, which imposes a financial burden with regard to proper disposal of the ash by-products. Clay-sludge is a wet clay slurring, and drying and transportation of this product entails substantial costs. Spent bleaching does not require much pre-treatment and is therefore the most promising alternative additive. On the other hand, bleaching earth contains residual plant oil which means that a range of legislation relating to waste combustion comes into play. Not least a waste combustion fee of 330 DKK/tonne. For all alternative (and commercial) additives disposal costs of the increase ash by-products represents a significant cost. This is

  12. A divergent synthetic approach to diverse molecular scaffolds: assessment of lead-likeness using LLAMA, an open-access computational tool.

    Science.gov (United States)

    Colomer, Ignacio; Empson, Christopher J; Craven, Philip; Owen, Zachary; Doveston, Richard G; Churcher, Ian; Marsden, Stephen P; Nelson, Adam

    2016-06-07

    Complementary cyclisation reactions of hex-2-ene-1,6-diamine derivatives were exploited in the synthesis of alternative molecular scaffolds. The value of the synthetic approach was analysed using LLAMA, an open-access computational tool for assessing the lead-likeness and novelty of molecular scaffolds.

  13. Coaching Conversations: Enacting Instructional Scaffolding

    Science.gov (United States)

    Gibson, Sharan A.

    2011-01-01

    This study analyzed coaching conversations and interviews of four coach/teacher partnerships for specific ways in which kindergarten and first-grade teachers, and coaches, conceptualized instructional scaffolding for guided reading. Interview transcripts were coded for coaches' and teachers' specific hypotheses/ ideas regarding instructional…

  14. Impact of electrical cardioversion for atrial fibrillation on left atrial appendage function and spontaneous echo contrast: characterization by simultaneous transesophageal echocardiography.

    Science.gov (United States)

    Grimm, R A; Stewart, W J; Maloney, J D; Cohen, G I; Pearce, G L; Salcedo, E E; Klein, A L

    1993-11-01

    This study assessed the function of the left atrial appendage in the pericardioversion period to gain insights into mechanisms involved in thromboembolism after cardioversion of atrial fibrillation. Systemic embolization associated with electrical cardioversion of atrial fibrillation is thought to originate from the left atrium or left atrial appendage, or both. However, the mechanism involved is poorly understood. We studied left atrial appendage function with transesophageal echocardiography in 20 patients with atrial fibrillation before and after successful electrical cardioversion. We measured left atrial appendage emptying and filling velocities by pulsed wave Doppler echocardiography, characterized Doppler emptying patterns, measured atrial appendage areas and assessed the presence or absence of spontaneous echo contrast or thrombus. Organized left atrial appendage function returned in 16 (80%) of 20 patients immediately after cardioversion. Atrial appendage emptying velocities before cardioversion were greater in patients without (0.39 +/- 0.02 m/s) than in those with (0.25 +/- 0.12 m/s) spontaneous echo contrast (p = 0.045). Furthermore, emptying velocities before cardioversion were significantly greater than late diastolic emptying velocities after cardioversion (0.31 +/- 0.15 vs. 0.14 +/- 0.12 m/s, p = 0.0001), as well as in both the group with (0.25 +/- 0.12 vs. 0.13 +/- 0.13 m/s, p = 0.001) and the group without (0.39 +/- 0.02 vs. 0.15 +/- 0.12 m/s, p = 0.01) spontaneous echo contrast. In addition, left atrial and atrial appendage spontaneous echo contrast developed in 4 of 20 patients and increased in intensity in 3 of 20 patients in the immediate postcardioversion period. Organized left atrial appendage function returns in most patients immediately after cardioversion of atrial fibrillation. However, its function is impaired compared with that before cardioversion. Furthermore, spontaneous echo contrast increased in 7 (35%) of 20 patients after

  15. Chitin Scaffolds in Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Tetsuya Furuike

    2011-03-01

    Full Text Available Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue engineering biomaterial lies in that it can be easily processed into gel and scaffold forms for a variety of biomedical applications. Moreover, chitin has been shown to enhance some biological activities such as immunological, antibacterial, drug delivery and have been shown to promote better healing at a faster rate and exhibit greater compatibility with humans. This review provides an overview of the current status of tissue engineering/regenerative medicine research using chitin scaffolds for bone, cartilage and wound healing applications. We also outline the key challenges in this field and the most likely directions for future development and we hope that this review will be helpful to the researchers working in the field of tissue engineering and regenerative medicine.

  16. Ceramic Identity Contributes to Mechanical Properties and Osteoblast Behavior on Macroporous Composite Scaffolds

    Directory of Open Access Journals (Sweden)

    J. Kent Leach

    2012-05-01

    Full Text Available Implants formed of metals, bioceramics, or polymers may provide an alternative to autografts for treating large bone defects. However, limitations to each material motivate the examination of composites to capitalize on the beneficial aspects of individual components and to address the need for conferring bioactive behavior to the polymer matrix. We hypothesized that the inclusion of different bioceramics in a ceramic-polymer composite would alter the physical properties of the implant and the cellular osteogenic response. To test this, composite scaffolds formed from poly(lactide-co-glycolide (PLG and either hydroxyapatite (HA, β-tricalcium phosphate (TCP, or bioactive glass (Bioglass 45S®, BG were fabricated, and the physical properties of each scaffold were examined. We quantified cell proliferation by DNA content, osteogenic response of human osteoblasts (NHOsts to composite scaffolds by alkaline phosphatase (ALP activity, and changes in gene expression by qPCR. Compared to BG-PLG scaffolds, HA-PLG and TCP-PLG composite scaffolds possessed greater compressive moduli. NHOsts on BG-PLG substrates exhibited higher ALP activity than those on control, HA-, or TCP-PLG scaffolds after 21 days, and cells on composites exhibited a 3-fold increase in ALP activity between 7 and 21 days versus a minimal increase on control scaffolds. Compared to cells on PLG controls, RUNX2 expression in NHOsts on composite scaffolds was lower at both 7 and 21 days, while expression of genes encoding for bone matrix proteins (COL1A1 and SPARC was higher on BG-PLG scaffolds at both time points. These data demonstrate the importance of selecting a ceramic when fabricating composites applied for bone healing.

  17. Scaffolding to Support Better Achievement in Mathematics

    Directory of Open Access Journals (Sweden)

    Nila Mareta Murdiyani

    2013-06-01

    Full Text Available According to the National Science Education Standards, teachers should emphasize students’ interests, needs, experiences, inquiry, collaboration and understanding in their classrooms. One of the characteristics of inquiry is using scaffolding. Because of the benefits, it is important to investigate the effect of scaffolding on achievement in mathematics. Based on some relevant previous studies, scaffolding can be used to support better achievement in mathematics. In scaffolding, teacher’s guidance decreases gradually and student’s autonomy increases gradually. By giving guidance, teacher revises student’s misconceptions; while by giving autonomy, teacher supports student’s motivation in learning. Minimizing misconceptions and maximizing motivation can lead students to better achievement in mathematics. Many studies in this paper emphasize the importance of teachers' contribution in giving scaffolding to their students. Further research should be conducted to investigate the role of other people surrounding the students, such as parent and peer, in supporting effective scaffolding. Keywords: scaffolding, achievement in mathematics, misconceptions, motivation

  18. Porous Hydroxyapatite Bioceramic Scaffolds for Drug Delivery and Bone Regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Loca, Dagnija; Locs, Janis; Salma, Kristine; Gulbis, Juris; Salma, Ilze; Berzina-Cimdina, Liga, E-mail: dagnija.loca@rtu.l [Riga Technical University, Riga Biomaterials innovation and development centre, Pulka 3/3, LV-1007, Riga (Latvia)

    2011-10-29

    The conventional methods of supplying a patient with pharmacologic active substances suffer from being very poorly selective, so that damage can occurs to the healthy tissues and organs, different from the intended target. In addition, high drug doses can be required to achieve the desired effect. An alternative approach is based on the use of implantable delivery tools, able to release the active substance in a controlled way. In the current research local drug delivery devices containing 8mg of gentamicin sulphate were prepared using custom developed vacuum impregnation technique. In vitro dissolution tests showed that gentamicin release was sustained for 12h. In order to decrease gentamicin release rate, biopolymer coatings were applied and coating structure investigated. The results showed that gentamicin release can be sustained for more than 70h for poly({epsilon}-caprolactone) coated calcium phosphate scaffolds. From poly lactic acid and polyvinyl alcohol coated scaffolds gentamicin was released within 20h and 50h, respectively.

  19. Mining for bioactive scaffolds with scaffold networks: improved compound set enrichment from primary screening data.

    Science.gov (United States)

    Varin, Thibault; Schuffenhauer, Ansgar; Ertl, Peter; Renner, Steffen

    2011-07-25

    Identification of meaningful chemical patterns in the increasing amounts of high-throughput-generated bioactivity data available today is an increasingly important challenge for successful drug discovery. Herein, we present the scaffold network as a novel approach for mapping and navigation of chemical and biological space. A scaffold network represents the chemical space of a library of molecules consisting of all molecular scaffolds and smaller "parent" scaffolds generated therefrom by the pruning of rings, effectively leading to a network of common scaffold substructure relationships. This algorithm provides an extension of the scaffold tree algorithm that, instead of a network, generates a tree relationship between a heuristically rule-based selected subset of parent scaffolds. The approach was evaluated for the identification of statistically significantly active scaffolds from primary screening data for which the scaffold tree approach has already been shown to be successful. Because of the exhaustive enumeration of smaller scaffolds and the full enumeration of relationships between them, about twice as many statistically significantly active scaffolds were identified compared to the scaffold-tree-based approach. We suggest visualizing scaffold networks as islands of active scaffolds.

  20. A comparative study of different imaging modalities for successful percutaneous left atrial appendage closure.

    Science.gov (United States)

    Chow, Danny Hf; Bieliauskas, Gintautas; Sawaya, Fadi J; Millan-Iturbe, Oscar; Kofoed, Klaus F; Søndergaard, Lars; De Backer, Ole

    2017-01-01

    Accurate sizing of the left atrial appendage (LAA) is essential when performing percutaneous LAA closure. This study aimed to compare different LAA imaging modalities and sizing methods in order to obtain successful LAA closure. Percutaneous LAA closure is an increasingly used treatment strategy to prevent stroke in patients with atrial fibrillation. LAA sizing has typically been done by 2D-transoesophageal echocardiography (TEE). Patients who had a preprocedural TEE and preprocedural and postprocedural multislice CT (MSCT) were identified. Preprocedural measurements of LAA ostia and landing zones by 2D-TEE, MSCT and angiography were collected and analysed for those patients with successful LAA closure - i.e. with no contrast leakage at 3-month follow-up MSCT. The study population (n=67) had a mean CHA2DS2-VASc score of 3.0 and HAS-BLED score of 2.7. Fifty-eight patients (87%) were identified to have successful LAA closure. Based on MSCT, 48 LAA sizings (83%) resulted in a correct LAA closure device size selection, whereas with 2D-TEE sizing, only 33 measurements (57%) would have resulted in a correct device size selection (pAmulet, WatchmanFLX), whereas the maximal diameter was the best parameter for the ‘open-end’ Watchman device. Preprocedural MSCT-based LAA closure device size selection proves to be a more accurate method than conventional 2D-TEE-based sizing. Depending on the LAA closure device design, perimeter-derived mean diameter or maximal diameter could be the better sizing method.

  1. Left atrial appendage occlusion in high-risk patients with non-valvular atrial fibrillation.

    Science.gov (United States)

    Berti, Sergio; Pastormerlo, Luigi Emilio; Rezzaghi, Marco; Trianni, Giuseppe; Paradossi, Umberto; Cerone, Elisa; Ravani, Marcello; De Caterina, Alberto Ranieri; Rizza, Antonio; Palmieri, Cataldo

    2016-12-15

    Percutaneous left atrial appendage (LAA) occlusion has been developed as a viable option for stroke and thromboembolism prevention in patients with non-valvular atrial fibrillation (NVAF) and at high risk for cerebral cardioembolic events. Data on device implantation and long-term follow-up from large cohorts are limited. 110 consecutive patients with NVAF and contraindications to oral anticoagulants (OACs) underwent LAA occlusion procedures and achieved a longer than 1 year follow-up. All patients were enrolled in a prospective registry. Procedures were performed using the Amplatzer Cardiac Plug or Amulet guided by fluoroscopy and intracardiac echocardiography. Mean age of the population was 77±6 years old; 68 were men. Atrial fibrillation was paroxysmal in 20%, persistent in 15.5% and permanent in 64.5% of cases, respectively. Mean CHA2DS2-VASc and HAS-BLED scores were 4.3±1.3 and 3.4±1, respectively. Technical success (successful deployment and implantation of device) was achieved in 100% of procedures. Procedural success (technical success without major procedure-related complications) was achieved in 96.4%, with a 3.6% rate of major procedural complications (three cases of pericardial tamponade requiring drainage and one case of major bleeding). Mean follow-up was 30±12 months (264 patient-years). Annual rates for ischaemic stroke and for other thromboembolic events were respectively 2.2% and 0%, and annual rate for major bleeding was 1.1%. Our data suggest LAA occlusion in high-risk patients with NVAF not suitable for OACs is feasible and associated with low complication rates as well as low rates of stroke and major bleeding at long-term follow-up. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  2. Twelve-month follow-up of left atrial appendage occlusion with Amplatzer Amulet.

    Science.gov (United States)

    Kleinecke, Caroline; Park, Jai-Wun; Gödde, Martin; Zintl, Konstantin; Schnupp, Steffen; Brachmann, Johannes

    2017-01-01

    The Amplatzer Amulet (St. Jude Medical, Minneapolis, MN, USA) is a second gen-eration Amplatzer device for left atrial appendage (LAA) occlusion (LAAO) for stroke prophylaxis in patients with atrial fibrillation. This research sought to assess the clinical performance of the Amplatzer Amulet device and in follow up for 12 months. In this single-center registry patients with atrial fibrillation and contraindication to oral anticoagulation underwent LAAO with the Amplatzer Amulet device. Follow-up was performed before discharge, by transesophageal echocardiography (TEE) after 6 weeks and telephone interview after 3, 6 and 12 months. Between October 2014 and August 2015 50 patients (76.1 ± 8.3 years; 30 male) were en-rolled. Procedural success was achieved in 49 (98%) patients. Major periprocedural adverse events were observed in 4 (8%) of patients: 1 device embolization, 2 pericardial effusions requiring pericardiocente-sis and 1 prolonged hospital stay due to retropharyngeal hematoma from the TEE probe. Follow-up TEE was available in 38 of 50 patients showing complete LAA sealing in all. 2 device-related thrombi were also documented. At 12-month follow-up 7 patients had died unrelated to the device. Ischemic stroke occurred in 3 patients. According to neurological examination two were classified as microangiopathic and not cardio-embolic. The other one could not be classified. Bleeding complications (5 minor, 3 major) were documented in 8 patients. Although minimizing procedure-related complications remains challenging, LAAO with the Amplatzer Amulet device showed high procedural success and excellent LAA sealing. (Cardiol J 2017; 24, 2: 131-138).

  3. Left atrial appendage morphology in patients with suspected cardiogenic stroke without known atrial fibrillation.

    Directory of Open Access Journals (Sweden)

    Miika Korhonen

    Full Text Available The left atrial appendage (LAA is the typical origin for intracardiac thrombus formation. Whether LAA morphology is associated with increased stroke/TIA risk is controversial and, if it does, which morphological type most predisposes to thrombus formation. We assessed LAA morphology in stroke patients with cryptogenic or suspected cardiogenic etiology and in age- and gender-matched healthy controls. LAA morphology and volume were analyzed by cardiac computed tomography in 111 patients (74 males; mean age 60 ± 11 years with acute ischemic stroke of cryptogenic or suspected cardiogenic etiology other than known atrial fibrillation (AF. A subgroup of 40 patients was compared to an age- and gender-matched control group of 40 healthy individuals (21 males in each; mean age 54 ± 9 years. LAA was classified into four morphology types (Cactus, ChickenWing, WindSock, CauliFlower modified with a quantitative qualifier. The proportions of LAA morphology types in the main stroke group, matched stroke subgroup, and control group were as follows: Cactus (9.0%, 5.0%, 20.0%, ChickenWing (23.4%, 37.5%, 10.0%, WindSock (47.7%, 35.0%, 67.5%, and CauliFlower (19.8%, 22.5%, 2.5%. The distribution of morphology types differed significantly (P<0.001 between the matched stroke subgroup and control group. The proportion of single-lobed LAA was significantly higher (P<0.001 in the matched stroke subgroup (55% than the control group (6%. LAA volumes were significantly larger (P<0.001 in both stroke study groups compared to controls patients. To conclude, LAA morphology differed significantly between stroke patients and controls, and single-lobed LAAs were overrepresented and LAA volume was larger in patients with acute ischemic stroke of cryptogenic or suspected cardiogenic etiology.

  4. Analog series-based scaffolds: computational design and exploration of a new type of molecular scaffolds for medicinal chemistry

    Science.gov (United States)

    Dimova, Dilyana; Stumpfe, Dagmar; Hu, Ye; Bajorath, Jürgen

    2016-01-01

    Aim: Computational design of and systematic search for a new type of molecular scaffolds termed analog series-based scaffolds. Materials & methods: From currently available bioactive compounds, analog series were systematically extracted, key compounds identified and new scaffolds isolated from them. Results: Using our computational approach, more than 12,000 scaffolds were extracted from bioactive compounds. Conclusion: A new scaffold definition is introduced and a computational methodology developed to systematically identify such scaffolds, yielding a large freely available scaffold knowledge base.

  5. Analog series-based scaffolds: computational design and exploration of a new type of molecular scaffolds for medicinal chemistry.

    Science.gov (United States)

    Dimova, Dilyana; Stumpfe, Dagmar; Hu, Ye; Bajorath, Jürgen

    2016-12-01

    Computational design of and systematic search for a new type of molecular scaffolds termed analog series-based scaffolds. From currently available bioactive compounds, analog series were systematically extracted, key compounds identified and new scaffolds isolated from them. Using our computational approach, more than 12,000 scaffolds were extracted from bioactive compounds. A new scaffold definition is introduced and a computational methodology developed to systematically identify such scaffolds, yielding a large freely available scaffold knowledge base.

  6. Understanding Alternative Education: A Mixed Methods Examination of Student Experiences

    Science.gov (United States)

    Farrelly, Susan Glassett; Daniels, Erika

    2014-01-01

    Alternative education plays a critical role in the opportunity gap that persists in the US public education system. However, there has been little research on alternative schools. Scaffolded by a theoretical framework constructed from critical theory, self-determination theory (SDT) and student voice, this research examined how well students in…

  7. Bioactive polymeric scaffolds for tissue engineering

    Directory of Open Access Journals (Sweden)

    Scott Stratton

    2016-12-01

    Full Text Available A variety of engineered scaffolds have been created for tissue engineering using polymers, ceramics and their composites. Biomimicry has been adopted for majority of the three-dimensional (3D scaffold design both in terms of physicochemical properties, as well as bioactivity for superior tissue regeneration. Scaffolds fabricated via salt leaching, particle sintering, hydrogels and lithography have been successful in promoting cell growth in vitro and tissue regeneration in vivo. Scaffold systems derived from decellularization of whole organs or tissues has been popular due to their assured biocompatibility and bioactivity. Traditional scaffold fabrication techniques often failed to create intricate structures with greater resolution, not reproducible and involved multiple steps. The 3D printing technology overcome several limitations of the traditional techniques and made it easier to adopt several thermoplastics and hydrogels to create micro-nanostructured scaffolds and devices for tissue engineering and drug delivery. This review highlights scaffold fabrication methodologies with a focus on optimizing scaffold performance through the matrix pores, bioactivity and degradation rate to enable tissue regeneration. Review highlights few examples of bioactive scaffold mediated nerve, muscle, tendon/ligament and bone regeneration. Regardless of the efforts required for optimization, a shift in 3D scaffold uses from the laboratory into everyday life is expected in the near future as some of the methods discussed in this review become more streamlined.

  8. Alginate based scaffolds for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Valente, J.F.A.; Valente, T.A.M. [CICS-UBI - Centro de Investigacao em Ciencias da Saude, Faculdade de Ciencias da Saude, Universidade da Beira Interior, Covilha (Portugal); Alves, P.; Ferreira, P. [CIEPQPF, Departamento de Engenharia Quimica, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-290 Coimbra (Portugal); Silva, A. [Centro de Ciencia e Tecnologia Aeroespaciais, Universidade da Beira Interior, Covilha (Portugal); Correia, I.J., E-mail: icorreia@ubi.pt [CICS-UBI - Centro de Investigacao em Ciencias da Saude, Faculdade de Ciencias da Saude, Universidade da Beira Interior, Covilha (Portugal)

    2012-12-01

    The design and production of scaffolds for bone tissue regeneration is yet unable to completely reproduce the native bone properties. In the present study new alginate microparticle and microfiber aggregated scaffolds were produced to be applied in this area of regenerative medicine. The scaffolds' mechanical properties were characterized by thermo mechanical assays. Their morphological characteristics were evaluated by isothermal nitrogen adsorption and scanning electron microscopy. The density of both types of scaffolds was determined by helium pycnometry and mercury intrusion porosimetry. Furthermore, scaffolds' cytotoxic profiles were evaluated in vitro by seeding human osteoblast cells in their presence. The results obtained showed that scaffolds have good mechanical and morphological properties compatible with their application as bone substitutes. Moreover, scaffold's biocompatibility was confirmed by the observation of cell adhesion and proliferation after 5 days of being seeded in their presence and by non-radioactive assays. - Highlights: Black-Right-Pointing-Pointer Design and production of scaffolds for bone tissue regeneration. Black-Right-Pointing-Pointer Microparticle and microfiber alginate scaffolds were produced through a particle aggregation technique; Black-Right-Pointing-Pointer Scaffolds' mechanically and biologically properties were characterized through in vitro studies;.

  9. Fabrication and characterization of chitosan/OGP coated porous poly(ε-caprolactone) scaffold for bone tissue engineering.

    Science.gov (United States)

    Cui, Zhixiang; Lin, Luyin; Si, Junhui; Luo, Yufei; Wang, Qianting; Lin, Yongnan; Wang, Xiaofeng; Chen, Wenzhe

    2017-03-14

    As one of the stimulators on bone formation, osteogenic growth peptide (OGP) improves both proliferation and differentiation of the bone cells in vitro and in vivo. The aim of this work was the preparation of three dimensional porous poly(ε-caprolactone) (PCL) scaffold with high porosity, well interpore connectivity, and then its surface was modified by using chitosan (CS)/OGP coating for application in bone regeneration. In present study, the properties of porous PCL and CS/OGP coated PCL scaffold, including the microstructure, water absorption, porosity, hydrophilicity, mechanical properties, and biocompatibility in vitro were investigated. Results showed that the PCL and CS/OGP-PCL scaffold with an interconnected network structure have a porosity of more than 91.5, 80.8%, respectively. The CS/OGP-PCL scaffold exhibited better hydrophilicity and mechanical properties than that of uncoated PCL scaffold. Moreover, the results of cell culture test showed that CS/OGP coating could stimulate the proliferation and growth of osteoblast cells on CS/OGP-PCL scaffold. These finding suggested that the surface modification could be a effective method on enhancing cell adhesion to synthetic polymer-based scaffolds in tissue engineering application and the developed porous CS/OGP-PCL scaffold should be considered as alternative biomaterials for bone regeneration.

  10. Structure-function studies of an engineered scaffold protein derived from stefin A. I: Development of the SQM variant.

    Science.gov (United States)

    Hoffmann, Toni; Stadler, Lukas Kurt Josef; Busby, Michael; Song, Qifeng; Buxton, Anthony T; Wagner, Simon D; Davis, Jason J; Ko Ferrigno, Paul

    2010-05-01

    Non-antibody scaffold proteins are used for a range of applications, especially the assessment of protein-protein interactions within human cells. The search for a versatile, robust and biologically neutral scaffold previously led us to design STM (stefin A triple mutant), a scaffold derived from the intracellular protease inhibitor stefin A. Here, we describe five new STM-based scaffold proteins that contain modifications designed to further improve the versatility of our scaffold. In a step-by-step approach, we introduced restriction sites in the STM open reading frame that generated new peptide insertion sites in loop 1, loop 2 and the N-terminus of the scaffold protein. A second restriction site in 'loop 2' allows substitution of the native loop 2 sequence with alternative oligopeptides. None of the amino acid changes interfered significantly with the folding of the STM variants as assessed by circular dichroism spectroscopy. Of the five scaffold variants tested, one (stefin A quadruple mutant, SQM) was chosen as a versatile, stable scaffold. The insertion of epitope tags at varying positions showed that inserts into loop 1, attempted here for the first time, were generally well tolerated. However, N-terminal insertions of epitope tags in SQM had a detrimental effect on protein expression.

  11. Multi-scale osteointegration and neovascularization of biphasic calcium phosphate bone scaffolds

    Science.gov (United States)

    Lan, Sheeny K.

    Bone grafts are utilized clinically to guide tissue regeneration. Autologous bone and allogeneic bone are the current clinical standards. However, there are significant limitations to their use. To address the need for alternatives to autograft and allograft, researchers have worked to develop synthetic grafts, also referred to as scaffolds. Despite extensive efforts in this area, a gap persists between basic research and clinical application. In particular, solutions for repairing critical size and/or load-bearing defects are lacking. The aim of this thesis work was to address two critical barriers preventing design of successful tissue engineering constructs for bone regeneration within critical size and/or load-bearing defects. Those barriers are insufficient osteointegration and slow neovascularization. In this work, the effects of scaffold microporosity, recombinant human bone morphogenetic protein-2 delivery and endothelial colony forming cell vasculogenesis were evaluated in the context of bone formation in vivo. This was accomplished to better understand the role of these factors in bone regeneration, which may translate to improvements in tissue engineering construct design. Biphasic calcium phosphate (BCP) scaffolds with controlled macro- and microporosity were implanted in porcine mandibular defects. Evaluation of the BCP scaffolds after in vivo implantation showed, for the first time, osteocytes embedded in bone within scaffold micropores (regenerating bone and this has significant implications with regard to improved scaffold mechanical properties. The presence of osteocytes within scaffold micropores is an indication of scaffold osteoinductivity because a chemotactic factor must be present to induce cell migration into pores on the order of the cell diameter. It is likely that the scaffold undergoes in vivo modifications involving formation of a biological apatite layer within scaffold micropores and possibly co-precipitation of endogenous

  12. In Vivo Production of Small Recombinant RNAs Embedded in a 5S rRNA-Derived Protective Scaffold.

    Science.gov (United States)

    Stepanov, Victor G; Fox, George E

    2015-01-01

    Preparative synthesis of RNA is a challenging task that is usually accomplished using either chemical or enzymatic polymerization of ribonucleotides in vitro. Herein, we describe an alternative approach in which RNAs of interest are expressed as a fusion with a 5S rRNA-derived scaffold. The scaffold provides protection against cellular ribonucleases resulting in cellular accumulations comparable to those of regular ribosomal RNAs. After isolation of the chimeric RNA from the cells, the scaffold can be removed if necessary by deoxyribozyme-catalyzed cleavage followed by preparative electrophoretic separation of the cleavage reaction products. The protocol is designed for sustained production of high quality RNA on the milligram scale.

  13. Basement membrane zone remodeling during appendageal development in human fetal skin. The absence of type VII collagen is associated with gelatinase-A (MMP2) activity.

    Science.gov (United States)

    Karelina, T V; Bannikov, G A; Eisen, A Z

    2000-02-01

    Epithelial cell adhesion, migration, and differentiation are controlled by interactions at the basement membrane zone (BMZ). Type VII collagen is the major collagenous component of anchoring fibrils that are essential for the attachment of the epidermis to the dermis. Gelatinase A (MMP-2) is believed to be necessary for the degradation of type VII collagen. In this study we have examined the in vivo distribution of type VII collagen and gelatinase A (Gel A) in the developing human epidermis and its appendages. At 13-15 wk of gestation a marked decrease in type VII collagen immunoreactivity was seen in the BMZ surrounding invading appendageal buds; however, type VII collagen mRNA was strongly expressed in the budding epidermal keratinocytes adjacent to the BMZ. At these stages, Gel A-positive mesenchymal-like cells were found scattered throughout the stroma with numerous Gel A-containing cells in direct contact with the developing appendageal buds. In situ zymography was used to show Gel A-activity in vivo. Gel A-mediated lysis was present at the interface between the appendageal buds and the underlying BMZ. By 20-25 wk of gestational age, immunostaining for type VII collagen protein was absent from the BMZ surrounding the distal portion of invading appendageal epithelial cords of both hair follicles and sweat glands. In contrast, type VII collagen mRNA was present in the basal keratinocytes adjacent to the BMZ surrounding the distal portion of these invading appendageal epithelial cords. At these stages Gel A-positive cells were present in the stroma directly adjacent to the distal portion of developing appendageal cords that lacked type VII collagen. In situ zymography showed zones of Gel A-mediated stromal lysis at the distal portion of developing appendageal cords. Interestingly, no differences were seen in the distribution of type IV collagen in the BMZ of both budding and resting fetal epidermis. These observations suggest that the absence of type VII collagen

  14. Molecular Recognition within Synaptic Scaffolds

    DEFF Research Database (Denmark)

    Erlendsson, Simon

    function. At the molecular level PICK1 contains both a BAR and a PDZ domain making it quite unique. Especially the specificity and promiscuity of the PICK1 PDZ domain seems to be more complicated than normally seen for PDZ domains. Also, the ability of PICK1 to form dimeric structures via its central BAR...... by the spatial architecture of the synapse itself. In this thesis, the molecular scaffolding mechanisms of PICK1 have been investigated in both isolated and near native conditions. Our findings have significantly benefitted the general understanding of how PICK1 and PDZ domain scaffolding works. In the first...... later in evolution to accommodate increasingly diverse PDZ domain ligands. Our findings provide basis for development of new and more specific peptide inhibitors. In the second study, we utilized SAXS, NMR spectroscopy, MD simulations and various other biochemical methods, to construct a full...

  15. Examinations of a new long-term degradable electrospun polycaprolactone scaffold in three rat abdominal wall models

    DEFF Research Database (Denmark)

    Jangö, Hanna; Gräs, Søren; Christensen, Lise

    2017-01-01

    Alternative approaches to reinforce native tissue in reconstructive surgery for pelvic organ prolapse are warranted. Tissue engineering combines the use of a scaffold with the regenerative potential of stem cells and is a promising new concept in urogynecology. Our objective was to evaluate whether....... Properties of the new neo-tissue construct must be evaluated at the time of full degradation of the scaffold before its possible clinical value in pelvic organ prolapse surgery can be evaluated....

  16. Hemolymph circulation in insect sensory appendages: functional mechanics of antennal accessory pulsatile organs (auxiliary hearts) in the mosquito Anopheles gambiae.

    Science.gov (United States)

    Boppana, Sushma; Hillyer, Julián F

    2014-09-01

    Mosquito antennae provide sensory input that modulates host-seeking, mating and oviposition behaviors. Thus, mosquitoes must ensure the efficient transport of molecules into and out of these appendages. To accomplish this, mosquitoes and other insects have evolved antennal accessory pulsatile organs (APOs) that drive hemolymph into the antennal space. This study characterizes the structural mechanics of hemolymph propulsion throughout the antennae of Anopheles gambiae. Using intravital video imaging, we show that mosquitoes possess paired antennal APOs that are located on each side of the head's dorsal midline. They are situated between the frons and the vertex in an area that is dorsal to the antenna but ventral to the medial-most region of the compound eyes. Antennal APOs contract in synchrony at 1 Hz, which is 45% slower than the heart. By means of histology and intravital imaging, we show that each antennal APO propels hemolymph into the antenna through an antennal vessel that traverses the length of the appendage and has an effective diameter of 1-2 μm. When hemolymph reaches the end of the appendage, it is discharged into the antennal hemocoel and returns to the head. Because a narrow vessel empties into a larger cavity, hemolymph travels up the antenna at 0.2 mm s(-1) but reduces its velocity by 75% as it returns to the head. Finally, treatment of mosquitoes with the anesthetic agent FlyNap (triethylamine) increases both antennal APO and heart contraction rates. In summary, this study presents a comprehensive functional characterization of circulatory physiology in the mosquito antennae.

  17. Percutaneous left atrial appendage occlusion - treatment outcomes and 6 months of follow-up - a single-center experience.

    Science.gov (United States)

    Karczewski, Michał; Woźniak, Sebastian; Skowronek, Radomir; Burysz, Marian; Fischer, Marcin; Anisimowicz, Lech; Demkow, Marcin; Konka, Marek; Ogorzeja, Wojciech

    2016-06-01

    To present the results of treatment and evaluate 6 months of follow-up in a group of patients with non-valvular atrial fibrillation, who underwent the procedure of percutaneous left atrial appendage occlusion (PLAAO). Percutaneous left atrial appendage occlusion was performed in 34 patients with non-valvular atrial fibrillation and contraindications for oral anticoagulation therapy. The risk of thromboembolic and bleeding complications was determined based on the CHA2DS2VASc and HAS-BLED scales. The Amplatzer Amulet system from St. Jude Medical was used. On the first postoperative day, all patients were started on double antiplatelet therapy with 75 mg/day of acetylsalicylic acid (ASA) and 75 mg/day of clopidogrel (CLO). On the 30(th) postoperative day, the efficacy of the antiplatelet therapy was assessed with impedance aggregometry using a Multiplate analyzer (Roche). Echocardiographic examinations were performed intraoperatively and on the first postoperative day; subsequently, follow-up examinations were conducted 1 and 6 months after the implantation. In all patients, proper occluder position was observed throughout the follow-up. No leakage or thrombi around the implants were found. No strokes or bleeding complications associated with the antiplatelet therapy were observed. Multiplate assessment of platelet activity was conducted in 20 out of 34 patients. The efficacy of ASA treatment was demonstrated in all patients; no response to clopidogrel treatment was observed in 5 out of 20 patients. One patient suffered from cardiac tamponade, which required the performance of full sternotomy. Local complications (hematomas of the inguinal region) were observed in 3 patients. One of the patients died for reasons unrelated to the procedure. Percutaneous left atrial appendage occlusion is an effective procedure in patients with non-valvular atrial fibrillation and contraindications for chronic anticoagulation therapy. Further observation is necessary to evaluate the

  18. Alternative Medicine

    Science.gov (United States)

    ... Involved News About Us Donate In This Section Alternative Medicine en Español email Send this article to a ... Dr. Yvonne Ou on Lifestyle Modifications and Glaucoma Alternative medicine may be defined as non-standard, unconventional treatments ...

  19. Controlled release of doxorubicin from electrospun PEO/chitosan/graphene oxide nanocomposite nanofibrous scaffolds.

    Science.gov (United States)

    Ardeshirzadeh, Behnaz; Anaraki, Nadia Aboutalebi; Irani, Mohammad; Rad, Leila Roshanfekr; Shamshiri, Soodeh

    2015-03-01

    Polyethylene oxide (PEO)/chitosan (CS)/graphene oxide (GO) electrospun nanofibrous scaffolds were successfully developed via electrospinning process for controlled release of doxorubicin (DOX). The SEM analysis of nanofibrous scaffolds with different contents of GO (0.1, 0.2, 0.5 and 0.7wt.%) indicated that the minimum diameter of nanofibers was found to be 85nm for PEO/CS/GO 0.5% nanofibers. The π-π stacking interaction between DOX and GO with fine pores of nanofibrous scaffolds exhibited higher drug loading (98%) and controlled release of the DOX loaded PEO/CS/GO nanofibers. The results of DOX release from nanofibrous scaffolds at pH5.3 and 7.4 indicated strong pH dependence. The hydrogen bonding interaction between GO and DOX could be unstable under acidic conditions which resulted in faster drug release rate in pH5.3. The cell viability results indicated that DOX loaded PEO/CS/GO/DOX nanofibrous scaffold could be used as an alternative source of DOX compared with free DOX to avoid the side effects of free DOX. Thus, the prepared nanofibrous scaffold offers as a novel formulation for treatment of lung cancer.

  20. The Amplatzer™ Cardiac Plug 2 for left atrial appendage occlusion: novel features and first-in-man experience.

    Science.gov (United States)

    Freixa, Xavier; Chan, Jason L K; Tzikas, Apostolos; Garceau, Patrick; Basmadjian, Arsène; Ibrahim, Réda

    2013-01-22

    Percutaneous left atrial appendage (LAA) closure is becoming a frequently performed procedure for patients with atrial fibrillation and high haemorrhagic risk. The Amplatzer™ Cardiac Plug (ACP) is one of the most commonly used devices for this purpose. Despite high success rate and low procedure risk associated with the ACP, a second generation of the device is now available. The new ACP has been designed to facilitate the implantation process, improve sealing performance and further reduce the risk of complications. The present report focuses on the novel features of the second generation of the Amplatzer™ Cardiac Plug (ACP 2 or Amulet™) and describes the first-in-man experience.

  1. Endoscopic Ultrasound for the Detection of Left Atrial Appendage Thrombus: A Useful Technique in Patients with Transesophageal Echocardiography Contraindication

    Science.gov (United States)

    Jurado-Román, Alfonso; López-Viedma, Bartolomé; Piqueras-Flores, Jesús; López-Lluva, María T.

    2016-01-01

    Endoscopic ultrasound is a diagnostic and therapeutic technique used in specialized centers for patients that have undergone digestive procedures. This technique enables highly precise real-time imaging of the digestive tract wall and surrounding organs. Endoscopic ultrasound is also useful in patients with cardiovascular diseases such as atrial fibrillation. In patients with contraindication for transesophageal echocardiography due to high risk of esophageal bleeding or complications that may require immediate intervention, endoscopic ultrasound may be a safer option for visualizing atrial chambers to rule out the presence of left atrial appendage thrombi before cardioversion. PMID:27642527

  2. Application of an Epicardial Left Atrial Appendage Occlusion Device by a Robotic-Assisted, Right Chest Approach.

    Science.gov (United States)

    Lewis, Clifton T P; Stephens, Richard L; Horst, Vernon D; Angelillo, Margaret; Tyndal, Charles M

    2016-05-01

    Closure of the left atrial appendage (LAA) has become a standard part of any mitral valve operation because it is thought to reduce the potential for late thrombus development and for embolic events. To date, surgeons performing robotic mitral valve operations have been limited to an endocardial approach to LAA closure. However, oversewing the orifice of the LAA is time consuming and lengthens the cross-clamp time, and failures to obtain permanent closure have been reported. We describe our technique for an epicardial approach that is safe and efficient and that gives a secure closure of the LAA.

  3. Interphotoreceptor matrix-poly(ϵ-caprolactone) composite scaffolds for human photoreceptor differentiation

    OpenAIRE

    Petr Baranov; Andrew Michaelson; Joydip Kundu; Carrier, Rebecca L; Michael Young

    2014-01-01

    Tissue engineering has been widely applied in different areas of regenerative medicine, including retinal regeneration. Typically, artificial biopolymers require additional surface modification (e.g. with arginine–glycine–aspartate-containing peptides or adsorption of protein, such as fibronectin), before cell seeding. Here, we describe an alternative approach for scaffold design: the manufacture of hybrid interphotore...

  4. Flow perfusion culture of human mesenchymal stem cells on coralline hydroxyapatite scaffolds with various pore sizes

    DEFF Research Database (Denmark)

    Bjerre, Lea; Bünger, Cody; Baatrup, Anette

    2011-01-01

    Bone grafts are widely used in orthopaedic reconstructive surgery, but harvesting of autologous grafts is limited due to donor site complications. Bone tissue engineering is a possible alternative source for substitutes, and to date, mainly small scaffold sizes have been evaluated. The aim of thi...

  5. Autologous cartilage fragments in a composite scaffold for one stage osteochondral repair in a goat model

    Directory of Open Access Journals (Sweden)

    A Marmotti

    2013-08-01

    Full Text Available We propose a culture-free approach to osteochondral repair with minced autologous cartilage fragments loaded onto a scaffold composed of a hyaluronic acid (HA-derived membrane, platelet-rich fibrin matrix (PRFM and fibrin glue. The aim of the study was to demonstrate in vitro the outgrowth of chondrocytes from cartilage fragments onto this scaffold and, in vivo, the formation of functional repair tissue in goat osteochondral defects. Two sections were considered: 1 in vitro: minced articular cartilage from goat stifle joints was loaded onto scaffolds, cultured for 1 or 2 months, and then evaluated histologically and immunohistochemically; 2 in vivo: 2 unilateral critically-sized trochlear osteochondral defects were created in 15 adult goats; defects were treated with cartilage fragments embedded in the scaffold (Group 1, with the scaffold alone (Group 2, or untreated (Group 3. Repair processes were evaluated morphologically, histologically, immunohistochemically and biomechanically at 1, 3, 6 and 12 months. We found that in vitro, chondrocytes from cartilage fragments migrated to the scaffold and, at 2 months, matrix positive for collagen type II was observed in the constructs. In vivo, morphological and histological assessment demonstrated that cartilage fragment-loaded scaffolds led to the formation of functional hyaline-like repair tissue. Repair in Group 1 was superior to that of control groups, both histologically and mechanically. Autologous cartilage fragments loaded onto an HA/PRFM/fibrin glue scaffold provided a viable cell source and allowed for an improvement of the repair process of osteochondral defects in a goat model, representing an effective alternative for one-stage repair of osteochondral lesions.

  6. The Effect of Aligned and Random Electrospun Fibrous Scaffolds on Rat Mesenchymal Stem Cell Proliferation

    Directory of Open Access Journals (Sweden)

    Zahra Zonoubi

    2012-01-01

    Full Text Available Objective: The development of combining mesenchymal stem cells (MSCs with surface modified three-dimensional (3D biomaterial scaffold provides a desirable alternative for replacement of damaged and diseased tissue. Nanofibrous scaffolds serve as suitable environment for cell attachment and proliferation due to their similarity to the physical dimension of the natural extracellular matrix. In this study the properties of plasma treated poly-C-caprolactone nanofiber scaffolds (p-PCL and unaltered PCL scaffolds were compared,and then p-PCL scaffolds were evaluated for MSC culture.Materials and Methods: Aligned and random PCL nanofibrus scaffolds were fabricatedby electrospining and their surface modified with O2 plasma treatment to enhanceMSC proliferation, adhesion and interaction. Chemical and mechanical characterizationswere carried out using scanning electron microscopy (SEM, water contact angle and tensile testing. Cell adhesion and morphology were evaluated using SEM 1 day after culture. Statistical analysis was carried out using one way analysis of variance(ANOVA.Results: The proliferation of MSCs were evaluated using 3-(4,5-Dimethylthiazol-2-yl-2,5-DiphenyltetrazoliumBromide(MTT assay on day 1, 3, and 5 after cell culture. Results showed that the numbers of cells that had grown on PCL nanofibrous scaffolds were significantly higher than those of control surfaces without nanofibers. Furthermore, the proliferation of MSCs on random nanofiber was significantly higher compared to that on aligned nanofiber.Conclusion: This study showed that while both aligned and random plasma treated PCL nanofibrous scaffold are more suitable substrates for MSC growth than tissue culture plates, random nanofiber best supported the proliferation of MSCs.

  7. Magnetically actuated tissue engineered scaffold: insights into mechanism of physical stimulation

    Science.gov (United States)

    Sapir-Lekhovitser, Yulia; Rotenberg, Menahem Y.; Jopp, Juergen; Friedman, Gary; Polyak, Boris; Cohen, Smadar

    2016-02-01

    Providing the right stimulatory conditions resulting in efficient tissue promoting microenvironment in vitro and in vivo is one of the ultimate goals in tissue development for regenerative medicine. It has been shown that in addition to molecular signals (e.g. growth factors) physical cues are also required for generation of functional cell constructs. These cues are particularly relevant to engineering of biological tissues, within which mechanical stress activates mechano-sensitive receptors, initiating biochemical pathways which lead to the production of functionally mature tissue. Uniform magnetic fields coupled with magnetizable nanoparticles embedded within three dimensional (3D) scaffold structures remotely create transient physical forces that can be transferrable to cells present in close proximity to the nanoparticles. This study investigated the hypothesis that magnetically responsive alginate scaffold can undergo reversible shape deformation due to alignment of scaffold's walls in a uniform magnetic field. Using custom made Helmholtz coil setup adapted to an Atomic Force Microscope we monitored changes in matrix dimensions in situ as a function of applied magnetic field, concentration of magnetic particles within the scaffold wall structure and rigidity of the matrix. Our results show that magnetically responsive scaffolds exposed to an externally applied time-varying uniform magnetic field undergo a reversible shape deformation. This indicates on possibility of generating bending/stretching forces that may exert a mechanical effect on cells due to alternating pattern of scaffold wall alignment and relaxation. We suggest that the matrix structure deformation is produced by immobilized magnetic nanoparticles within the matrix walls resulting in a collective alignment of scaffold walls upon magnetization. The estimated mechanical force that can be imparted on cells grown on the scaffold wall at experimental conditions is in the order of 1 pN, which

  8. Cell–scaffold interaction within engineered tissue

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Haiping; Liu, Yuanyuan, E-mail: Yuanyuan_liu@shu.edu.cn; Jiang, Zhenglong; Chen, Weihua; Yu, Yongzhe; Hu, Qingxi

    2014-05-01

    The structure of a tissue engineering scaffold plays an important role in modulating tissue growth. A novel gelatin–chitosan (Gel–Cs) scaffold with a unique structure produced by three-dimensional printing (3DP) technology combining with vacuum freeze-drying has been developed for tissue-engineering applications. The scaffold composed of overall construction, micro-pore, surface morphology, and effective mechanical property. Such a structure meets the essential design criteria of an ideal engineered scaffold. The favorable cell–matrix interaction supports the active biocompatibility of the structure. The structure is capable of supporting cell attachment and proliferation. Cells seeded into this structure tend to maintain phenotypic shape and secreted large amounts of extracellular matrix (ECM) and the cell growth decreased the mechanical properties of scaffold. This novel biodegradable scaffold has potential applications for tissue engineering based upon its unique structure, which acts to support cell growth. - Highlights: • The scaffold is not only for providing a surface for cell residence but also for determining cell phenotype and retaining structural integrity. • The mechanical property of scaffold can be affected by activities of cell. • The scaffold provides a microenvironment for cell attachment, growth, and migration.

  9. Oriented Collagen Scaffolds for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Shohta Kodama

    2012-03-01

    Full Text Available Oriented collagen scaffolds were developed in the form of sheet, mesh and tube by arraying flow-oriented collagen string gels and dehydrating the arrayed gels. The developed collagen scaffolds can be any practical size with any direction of orientation for tissue engineering applications. The birefringence of the collagen scaffolds was quantitatively analyzed by parallel Nicols method. Since native collagen in the human body has orientations such as bone, cartilage, tendon and cornea, and the orientation has a special role for the function of human organs, the developed various types of three-dimensional oriented collagen scaffolds are expected to be useful biomaterials for tissue engineering and regenerative medicines.

  10. Early Canadian Multicenter Experience With WATCHMAN for Percutaneous Left Atrial Appendage Closure.

    Science.gov (United States)

    Saw, Jacqueline; Fahmy, Peter; Azzalini, Lorenzo; Marquis, Jean-Francois; Hibbert, Benjamin; Morillo, Carlos; Carrizo, Aldo; Ibrahim, Reda

    2017-04-01

    There are limited data with WATCHMAN (Boston Scientific Corporation, Natick, MA, USA) for left atrial appendage (LAA) closure in patients with nonvalvular atrial fibrillation (AF) and contraindications to anticoagulation. The purpose of this study was to evaluate the safety and efficacy of WATCHMAN in our early Canadian experience. We report our pooled consecutive series of patients who underwent WATCHMAN implantation at four major Canadian centers. Indications for LAA closure were CHADS2 ≥ 1 or CHA2 DS2 -VASc ≥ 2, and contraindication/intolerance to or failure on anticoagulation. Follow-up imaging was typically performed 1-6 months postprocedure. One hundred and six patients underwent LAA closure with WATCHMAN from May 2013 to October 2015. The mean age was 74.8 ± 7.7, mean CHADS2 score was 2.8 ± 1.2, CHA2 DS2 -VASc score was 4.3 ± 1.5, and HASBLED score was 3.2 ± 1.2. Permanent AF was present in 67.9% and paroxysmal AF in 32.1%. Indications for LAA closure were prior bleeding 89.6% (87 major bleeding and 8 minor bleeding), 9.4% were deemed high risk for bleeding, and 0.9% with recurrent strokes on warfarin. Procedural success was 97.2% (103 of 106), with one device embolization (snared percutaneously), one implant failure due to inadequate LAA depth, and one cardiac perforation requiring surgical repair before WATCHMAN implantation. The composite major safety event-rate was 1.9% (1 death and 1 device embolization). Mean hospital stay was 1.8 ± 4.7 days. Antithrombotic therapy postimplant included dual antiplatelet therapy in 76 of 103 (73.8%). Mean follow-up was 210 ± 182 days; there were two transient ischemic attacks, with estimated 66% reduction in thromboembolic events relative to CHADS2 predicted risk. In our early Canadian experience, WATCHMAN for LAA closure in patients contraindicated to anticoagulation appeared safe and effective. © 2017 Wiley Periodicals, Inc.

  11. Left Atrial Appendage Closure for Atrial Fibrillation Is Safe and Effective After Intracranial or Intraocular Hemorrhage.

    Science.gov (United States)

    Fahmy, Peter; Spencer, Ryan; Tsang, Michael; Gooderham, Peter; Saw, Jacqueline

    2016-03-01

    Atrial fibrillation (AF) affects 1%-2% of the general population and 13% of individuals older than 80 years of age. Anticoagulation has been the mainstay therapy to reduce stroke risk. Patients with previous intracranial hemorrhage (ICH) or intraocular hemorrhage (IOH) are at increased risk of recurrence if anticoagulation is continued or initiated. Left atrial appendage (LAA) closure may obviate the need for long-term anticoagulation in these patients. We report our consecutive series of patients with nonvalvular AF with previous ICH or IOH who underwent LAA closure with the AMPLATZER Cardiac Plug (ACP; St Jude Medical, St Paul, MN), AMPLATZER Amulet, or WATCHMAN (Boston Scientific, Natick, MA) device. Demographics, clinical status, procedural outcomes, and complications were collected at baseline, during the procedure, at 3 months, at 1 year, and annually thereafter. Twenty-six patients with previous ICH (n = 24) or IOH (n = 2) underwent LAA closure (9 with the ACP, 3 with the Amulet, and 7 with the WATCHMAN). The mean age was 76 ± 7 years, and 61.5% were men with a mean CHADS2 (Congestive Heart Failure, Hypertension, Age, Diabetes, Stroke/Transient Ischemic Attack) score of 3.2 ± 1.4 and CHA2DS2-VASc (Congestive Heart Failure, Hypertension, Age [≥ 75 years], Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age [65-74 years], Sex [Female] score) of 4.9 ± 1.7. No procedure-related complications occurred. Mean follow-up was 11.9 ± 13.3 months. One patient died at 13 months (this death was not related to the procedure), and 1 patient had a transient ischemic attack at 20.6 months after the procedure. No ischemic stroke, haemorrhagic stroke, or bleeding problems occurred during follow-up. In our consecutive series, LAA closure was found to be safe and effective in patients with AF and a history of ICH or IOH. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  12. Comparing Measurements of CT Angiography, TEE, and Fluoroscopy of the Left Atrial Appendage for Percutaneous Closure.

    Science.gov (United States)

    Saw, Jacqueline; Fahmy, Peter; Spencer, Ryan; Prakash, Roshan; McLaughlin, Patrick; Nicolaou, Savvas; Tsang, Michael

    2016-04-01

    Left atrial appendage (LAA) closure requires accurate preprocedural measurements, and trans-esophageal echocardiography (TEE), cardiac computed tomography angiography (CCTA) and fluoroscopy can be utilized. However, correlations between these measurements remain inadequately assessed. Patients who underwent LAA closure at Vancouver General Hospital who had baseline LAA measurements by CCTA, TEE, and fluoroscopy were included in this analysis. CCTAs were performed with prospective-ECG-gating with Toshiba 320-detector or Siemens second generation 128-slice dual-source scanners, and images interpreted with VitreaWorkstation.™ LAA maximal dimensions were obtained for all patients at: (1) Amplatzer Cardiac Plug (ACP)/Amulet landing zone 10 mm within orifice, (2) WATCHMAN ostium, and (3) WATCHMAN depth measurements. Correlations and agreements were compared. We report 50 consecutive patients who underwent LAA closure (8 ACP, 10 Amulet, 32 WATCHMAN). Average age was 75.2 ± 8.7 years, mean CHADS2 score 3.0 ± 1.3, and CHA2 DS2 -VASc 4.7 ± 1.5. Procedural device implantation success was 100%. For ACP landing zone, mean maximal measurements were 24.1 ± 4.7 mm with CCTA, 22.3 ± 4.9 mm TEE, and 19.9 ± 5.6 mm fluoroscopy (P < 0.001); R value 0.81 fluoroscopy/CTA, 0.67 fluoroscopy/TEE, and 0.80 CTA/TEE. For WATCHMAN ostium, mean maximal measurements were 25.8 ± 4.7 mm CCTA (P < 0.001 vs. fluoroscopy, P = 0.16 vs. TEE), 25.1 ± 4.4 mm TEE (P = 0.016 vs. fluoroscopy), and 23.8 ± 4.9 mm fluoroscopy; R value 0.71 fluoroscopy/CTA, 0.65 fluoroscopy/TEE, and 0.74 CTA/TEE. Depth measurements were 34.3 ± 5.7 mm with CCTA, 31.1 ± 6.5 mm TEE, and 27.8 ± 7.1 mm fluoroscopy (all P < 0.01); and correlations with R value 0.28 fluoroscopy/CTA, 0.22 fluoroscopy/TEE, and 0.56 CTA/TEE. All 3 imaging modalities correlated with ACP landing zone and WATCHMAN ostium measurements, with CCTA providing the largest measurements, followed by TEE and fluoroscopy. © 2016 Wiley Periodicals, Inc.

  13. Predictors of Early (1-Week) Outcomes Following Left Atrial Appendage Closure With Amplatzer Devices.

    Science.gov (United States)

    Koskinas, Konstantinos C; Shakir, Samera; Fankhauser, Máté; Nietlispach, Fabian; Attinger-Toller, Adrian; Moschovitis, Aris; Wenaweser, Peter; Pilgrim, Thomas; Stortecky, Stefan; Praz, Fabien; Räber, Lorenz; Windecker, Stephan; Meier, Bernhard; Gloekler, Steffen

    2016-07-11

    The aim of this study was to assess predictors of adverse 1-week outcomes and determine the effect of left atrial appendage (LAA) morphology following LAA closure (LAAC) with Amplatzer devices. Percutaneous LAAC is a valuable treatment option for stroke prevention in patients with atrial fibrillation. Determinants of procedural safety events with Amplatzer occluders are not well established, and the possibly interrelating effect of LAA anatomy is unknown. Between 2009 and 2014, 500 consecutive patients with atrial fibrillation ineligible or at high risk for oral anticoagulation underwent LAAC using Amplatzer devices. Procedure- and device-related major adverse events (MAEs) were defined as the composite of death, stroke, major or life-threatening bleeding, serious pericardial effusion, device embolization, major access-site vascular complication, or need for cardiovascular surgery within 7 days following the intervention. Patients (mean age 73.9 ± 10.1 years) were treated with Amplatzer Cardiac Plug (n = 408 [82%]) or Amulet (n = 92 [18%]) devices. Early procedural success was 97.8%, and MAEs occurred in 29 patients (5.8%). Independent predictors of MAEs included device repositioning (odds ratio: 9.13; 95% confidence interval: 2.85 to 33.54; p < 0.001) and left ventricular ejection fraction <30% (odds ratio: 4.08; 95% confidence interval: 1.49 to 11.20; p = 0.006), with no effect of device type or size. Angiographic LAA morphology, characterized as cauliflower (33%), cactus (32%), windsock (20%), or chicken wing (15%), was not associated with procedural success (p = 0.51) or the occurrence of MAEs (p = 0.78). In this nonrandomized study, procedural success of LAAC using Amplatzer devices was high. MAEs within 7 days were predicted by patient- and procedure-related factors. Although LAA morphology displayed substantial heterogeneity, outcomes were comparable across the spectrum of LAA anatomies. Copyright © 2016 American College of Cardiology Foundation

  14. Percutaneous left atrial appendage occlusion procedures in patients with heart failure.

    Science.gov (United States)

    Szymała, Magdalena; Streb, Witold; Mitręga, Katarzyna; Podolecki, Tomasz; Mencel, Grzegorz; Kukulski, Tomasz; Kalarus, Zbigniew

    2017-01-01

    Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia. Percutaneous left atrial appendage occlusion (LAAO) may be considered for stroke prophylaxis in patients with nonvalvular AF (NVAF), especially in contraindications for oral anticoagulants (OAC) or high risk of bleeding. The data about implantation, safety, efficacy, and follow-up are limited. Moreover, there are no studies on patients with NVAF and heart failure with severe left ventricular systolic dysfunction (left ventricular ejection fraction [LVEF] ≤ 35%). To assess the safety, efficacy, and mid-term outcomes of LAAO procedures with Amplatzer Cardiac Plug (ACP) and Amplatzer Amulet device in patients with NVAF and heart failure with LVEF ≤ 35% (group I) and to perform a comparative analysis of the patients who had LAAO with NVAF and LVEF > 35%. The analysis included 80 patients (group I: 19, group II: 61) with NVAF. The patients were enrolled for the study if they had: CHA2DS2VASc ≥ 2 and high risk of bleeding assessed in HAS-BLED (≥ 3) or less points in HAS-BLED but coexisting contraindications for OAC, or thromboembolic complications while using OAC. Time of follow-up was six months. In the studied population, the median CHA2DS2VASc score was 4 and the average HAS-BLED score was 3.2. Device implantation was successful in all patients from group I and in 59/61 patients from group II. The periprocedural clinical ef-ficacy (no thromboembolic complications) was 100% in group I and 98.4% in group II. Serious periprocedural complications (cardiac tamponade: 2.5%, device embolisation: 1.25%, unexplained death: 1.25%) occurred only in patients from group II (p = NS). The mid-term clinical efficacy was 100% in group I and 98.3% in group II (p = NS). During follow-up, one transient ischaemic attack and three deaths not related to the procedure occurred. Percutaneous LAAO is an effective and safe procedure in patients with NVAF and severe systolic heart failure. No significant

  15. 3D Tissue Scaffold Printing On Custom Artificial Bone Applications

    Directory of Open Access Journals (Sweden)

    Betül ALDEMİR

    2015-01-01

    Full Text Available Production of defect-matching scaffolds is the most critical step in custom artificial bone applications. Three dimensional printing (3DP is one of the best techniques particularly for custom designs on artificial bone applications because of the high controllability and design independency. Our long-term aim is to implant an artificial custom bone that is cultured with patient's own mesenchymal stem cells after determining defect architecture on patient's bone by using CT-scan and printing that defect-matching 3D scaffold with appropriate nontoxic materials. In this study, preliminary results of strength and cytotoxicity measurements of 3D printed scaffolds with modified calcium sulfate compositepowder (MCSCP were presented. CAD designs were created and MCSCP were printed by a 3D printer (3DS, Visijet, PXL Core. Some samples were covered with salt solution in order to harden the samples. MCSCP and salt coated MCSCP were the two experimental groups in this study. Cytotoxicity and mechanical experiments were performed after surface examination withscanning electron microscope (SEM and light microscope. Tension tests were performed for MCSCP and salt coated MCSCP samples. The 3D scaffolds were sterilized with ethylene oxide gas sterilizer, ventilated and conditioned with DMEM (10% FBS. L929 mouse fibroblast cells were cultured on scaffolds (3 repetitive and cell viability was determined using MTT analysis. According to the mechanical results, the MCSCP group stands until average 71,305 N, while salt coated MCSCP group stands until 21,328N. Although the strength difference between two groups is statistically significant (p=0.001, Mann-Whitney U, elastic modulus is not (MCSCP=1,186Pa, salt coated MCSCP=1,169Pa, p=0.445. Cell viability (MTT analysis results on day 1, 3, and 5 demonstrated thatscaffolds hadno toxic effect to the L929 mouse fibroblast cells. Consequently, 3D printed samples with MCSCP could potentially be a strong alternative

  16. Scaffolding in teacher-student interaction: a decade of research

    NARCIS (Netherlands)

    van de Pol, J.; Volman, M.; Beishuizen, J.

    2010-01-01

    Although scaffolding is an important and frequently studied concept, much discussion exists with regard to its conceptualizations, appearances, and effectiveness. Departing from the last decade’s scaffolding literature, this review scrutinizes these three areas of scaffolding. First, contingency, fa

  17. Metamorphic labral axis patterning in the beetle Tribolium castaneum requires multiple upstream, but few downstream, genes in the appendage patterning network.

    Science.gov (United States)

    Smith, Frank W; Angelini, David R; Gaudio, Matthew S; Jockusch, Elizabeth L

    2014-03-01

    The arthropod labrum is an anterior appendage-like structure that forms the dorsal side of the preoral cavity. Conflicting interpretations of fossil, nervous system, and developmental data have led to a proliferation of scenarios for labral evolution. The best supported hypothesis is that the labrum is a novel structure that shares development with appendages as a result of co-option. Here, we use RNA interference in the red flour beetle Tribolium castaneum to compare metamorphic patterning of the labrum to previously published data on ventral appendage patterning. As expected under the co-option hypothesis, depletion of several genes resulted in similar defects in the labrum and ventral appendages. These include proximal deletions and proximal-to-distal transformations resulting from depletion of the leg gap genes homothorax and extradenticle, large-scale deletions resulting from depletion of the leg gap gene Distal-less, and smaller distal deletions resulting from knockdown of the EGF ligand Keren. However, depletion of dachshund and many of the genes that function downstream of the leg gap genes in the ventral appendages had either subtle or no effects on labral axis patterning. This pattern of partial similarity suggests that upstream genes act through different downstream targets in the labrum. We also discovered that many appendage axis patterning genes have roles in patterning the epipharyngeal sensillum array, suggesting that they have become integrated into a novel regulatory network. These genes include Notch, Delta, and decapentaplegic, and the transcription factors abrupt, bric à brac, homothorax, extradenticle and the paralogs apterous a and apterous b.

  18. Metacognitive scaffolding during collaborative learning: a promising combination

    OpenAIRE

    Molenaar, Inge; Sleegers, Peter; Boxtel, van, M.

    2014-01-01

    This article explores the effect of computerized scaffolding with different scaffolds (structuring vs. problematizing) on intra-group metacognitive interaction. In this study, we investigate 4 types of intra-group social metacognitive activities; namely ignored, accepted, shared and co-constructed metacognitive activities in 18 triads (6 control groups; no scaffolds and 12 experimental groups; 6 structuring scaffolds and 6 problematizing scaffolds).We found that groups receiving scaffolding s...

  19. Pore architecture and cell viability on freeze dried 3D recombinant human collagen-peptide (RHC)–chitosan scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Zhou, Aimei; Deng, Aipeng [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Yang [Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Gao, Lihu; Zhong, Zhaocai [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Shulin, E-mail: yshulin@njust.edu.cn [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2015-04-01

    Pore architecture of 3D scaffolds used in tissue engineering plays a critical role in the maintenance of cell survival, proliferation and further promotion of tissue regeneration. We investigated the pore size and structure, porosity, swelling as well as cell viability of a series of recombinant human collagen-peptide–chitosan (RHCC) scaffolds fabricated by lyophilization. In this paper, freezing regime containing a final temperature of freezing (T{sub f}) and cooling rates was applied to obtain scaffolds with pore size ranging from 100 μm to 120 μm. Other protocols of RHC/chitosan suspension concentration and ratio modification were studied to produce more homogenous and appropriate structural scaffolds. The mean pore size decreased along with the decline of T{sub f} at a slow cooling rate of 0.7 °C/min; a more rapid cooling rate under 5 °C/min resulted to a smaller pore size and more homogenous microstructure. High concentration could reduce pore size and lead to thick well of scaffold, while improved the ratio of RHC, lamellar and fiber structure coexisted with cellular pores. Human umbilical vein endothelial cells (HUVECs) were seeded on these manufactured scaffolds, the cell viability represented a negative correlation to the pore size. This study provides an alternative method to fabricate 3D RHC–chitosan scaffolds with appropriate pores for potential tissue engineering. - Highlights: • Fabrication of recombinant human collagen-chitosan scaffolds by freezing drying • Influence of freeze drying protocols on lyophilized scaffolds • Pore size, microstructure, porosity, swelling and cell viability were compared. • The optimized porous scaffold is suitable for cell (HUVEC) seeding.

  20. Myxobolus turpisrotundus (Myxosporea: Bivalvulida) spores with caudal appendages: investigating the validity of the genus Henneguya with morphological and molecular evidence.

    Science.gov (United States)

    Liu, Yang; Whipps, Christopher M; Gu, Z M; Zeng, L B

    2010-08-01

    Spores of the myxozoan parasite Myxobolus turpisrotundus Zhang 2009 were observed for the first time bearing caudal appendages. Most spores had the typical Myxobolus spp. morphology, but approximately 10% of spores possessed a spore body that was slightly elongated with a short tail projecting from the spore valve. In other spores, the tail was much more clearly visible and elongate. The spore body of these unusual spores is consistent in morphology and dimension to the normal spores of M. turpisrotundus. Both spore types were found within individual cysts, and the small subunit ribosomal RNA (ssrRNA) gene sequence from parasite cysts of this type was nearly identical to the previously published sequence of M. turpisrotundus from allogynogenetic gibel carp Carassius auratus gibelio (Bloch). The phenomenon of Myxobolus spores with caudal appendages provides additional evidence that the use of this character to separate Myxobolus and Henneguya into distinct genera is not reflective of an evolutionarily accurate classification scheme. Phylogenetic analysis of ssrDNA sequence from Myxobolus and Henneguya species showed clustering of species in some locations of the tree, but ultimately these genera are intermixed. The use of a single character to delineate species in the two most species-rich myxozoan genera has been consistently challenged where DNA analyses are used. The present finding of a single species bearing both Myxobolus-type and Henneguya-type spores emphasizes the inadequacy of this classification scheme, and highlights the need for careful consideration of these variable characteristics when describing myxozoan species.

  1. Frequency-tuning input-shaped manifold-based switching control for underactuated space robot equipped with flexible appendages

    Science.gov (United States)

    Kojima, Hirohisa; Ieda, Shoko; Kasai, Shinya

    2014-08-01

    Underactuated control problems, such as the control of a space robot without actuators on the main body, have been widely investigated. However, few studies have examined attitude control problems of underactuated space robots equipped with a flexible appendage, such as solar panels. In order to suppress vibration in flexible appendages, a zero-vibration input-shaping technique was applied to the link motion of an underactuated planar space robot. However, because the vibrational frequency depends on the link angles, simple input-shaping control methods cannot sufficiently suppress the vibration. In this paper, the dependency of the vibrational frequency on the link angles is measured experimentally, and the time-delay interval of the input shaper is then tuned based on the frequency estimated from the link angles. The proposed control method is referred to as frequency-tuning input-shaped manifold-based switching control (frequency-tuning IS-MBSC). The experimental results reveal that frequency-tuning IS-MBSC is capable of controlling the link angles and the main body attitude to maintain the target angles and that the vibration suppression performance of the proposed frequency-tuning IS-MBSC is better than that of a non-tuning IS-MBSC, which does not take the frequency variation into consideration.

  2. Left atrial appendage occlusion with the AMPLATZER Amulet device: an expert consensus step-by-step approach.

    Science.gov (United States)

    Tzikas, Apostolos; Gafoor, Sameer; Meerkin, David; Freixa, Xavier; Cruz-Gonzalez, Ignacio; Lewalter, Thorsten; Saw, Jacqueline; Berti, Sergio; Nielsen-Kudsk, Jens Erik; Ibrahim, Reda; Lakkireddy, Dhanunjaya; Paul, Vincent; Arzamendi, Dabit; Nietlispach, Fabian; Worthley, Stephen G; Hildick-Smith, David; Thambo, Jean Benoit; Tondo, Claudio; Aminian, Adel; Kalarus, Zbigniew; Schmidt, Boris; Sondergaard, Lars; Kefer, Joelle; Meier, Bernhard; Park, Jai-Wun; Sievert, Horst; Omran, Heyder

    2016-04-20

    This document aims to describe a standardised methodology for performing left atrial appendage occlusion (LAAO) using the AMPLATZER Amulet device, and to provide useful tips and tricks for operators with different levels of experience. Physicians who are experts in LAAO and had personal clinical experience with the AMPLATZER Amulet device were asked to contribute in the preparation of this consensus document. Twenty-seven physicians (20 interventional cardiologists and 7 electrophysiologists) from 14 different countries reviewed the manuscript. A step-by-step approach, simulating a real case, was followed. Starting with patient selection and planning, related cardiac imaging is discussed, followed by vascular access - transseptal puncture optimisation. Then, angiographic calibration/sizing and the required fluoroscopy views are explained and a device sizing strategy is proposed. Device preparation and de-airing is briefly described, followed by sheath exchange, device deployment steps, evaluation of device stability and decision for final release. The way to recapture and change a device is then shown, together with some additional tips on how to deal with challenging anatomies like "chicken wing" left atrial appendage. Finally, for operators who are switching from AMPLATZER Cardiac Plug to Amulet, the main differences between the two devices with respect to implantation technique are presented. In conclusion, this document reflects a consensus approach by expert implanters on the steps of LAAO technique and best practices for implantation of the AMPLATZER Amulet device, along with some practical tips to minimise the complication rate.

  3. Aneurisma de apêndice atrial esquerdo: diagnóstico ecocardiográfico Left atrial appendage aneurysm: echocardiografic diagnostic

    Directory of Open Access Journals (Sweden)

    Viviane Cordeiro Veiga

    2008-05-01

    Full Text Available O aneurisma de apêndice atrial esquerdo é condição rara que se manifesta freqüentemente por arritmias cardíacas ou tromboembolismo. Relatamos um caso de paciente portador de aneurisma de apêndice atrial esquerdo, diagnosticado pela ecocardiografia e submetido a ressecção cirúrgica.The left atrial appendage aneurysm is a rare condition that frequently manifests itself by heart arrhythmias or thromboembolism. We report the case of a patient with left atrial appendage aneurysm, diagnosed by echocardiography and submitted to surgical resection.

  4. Biocompatibility and Structural Features of Biodegradable Polymer Scaffolds.

    Science.gov (United States)

    Nasonova, M V; Glushkova, T V; Borisov, V V; Velikanova, E A; Burago, A Yu; Kudryavtseva, Yu A

    2015-11-01

    We performed a comparative analysis of physicochemical properties and biocompatibility of scaffolds of different composition on the basis of biodegradable polymers fabricated by casting and electrospinning methods. For production of polyhydroxyalkanoate-based scaffolds by electrospinning method, the optimal concentration of the polymer was 8-10%. Fiber diameter and properties of the scaffold produced by electrospinning method depended on polymer composition. Addition of polycaprolactone increased elasticity of the scaffolds. Bio- and hemocompatibility of the scaffolds largely depended on the composition formulation and method of scaffold fabrication. Polylactide introduced into the composition of polyhydroxybutyrate-oxyvalerate scaffolds accelerated degradation and increased adhesive properties of the scaffolds.

  5. Metal nanodot arrays fabricated via seed-mediated electroless plating with block copolymer thin film scaffolding.

    Science.gov (United States)

    Komiyama, Hideaki; Iyoda, Tomokazu; Sanji, Takanobu

    2015-10-02

    We present an alternative approach to fabricating hexagonally arranged nanodot arrays of various metals by seed-mediated electroless plating with a cylinder-forming block copolymer thin film, PEO-b-PMA(Az), as a scaffold. Metal ions were selectively incorporated into PEO cylinders, followed by their reduction to metal and the etching of the scaffold to obtain highly ordered seed arrays of Au, Pd, and Pt. Nanodot arrays of the target metals (Au, Ag, and Ni) were selectively grown on the seed with their highly ordered arrangement by electroless plating. We studied the fabrication processes' suitability for control of the nanodot array size, as well as the plasmonic properties thereof.

  6. A practice scaffolding interactive platform

    DEFF Research Database (Denmark)

    Bundsgaard, Jeppe

    2009-01-01

    , structures the students' activity, and interactively supports subject learning. A PracSIP facilitates students' development of complex competencies, and at the same time it supports the students' development of skills defined in the curriculum. The paper introduces the concept, presents the theoretical......A Practice Scaffolding Interactive Platform (PracSIP) is a social learning platform which supports students in collaborative project based learning by simulating a professional practice. A PracSIP puts the core tools of the simulated practice at the students' disposal, it organizes collaboration...

  7. Scaffold Diversity from N-Acyliminium Ions

    DEFF Research Database (Denmark)

    Wu, Peng; Nielsen, Thomas E

    2017-01-01

    of structurally diverse scaffolds, ranging from simple bicyclic skeletons to complex polycyclic systems and natural-product-like compounds. This review aims to provide an overview of cyclization reactions of N-acyliminium ions derived from various precursors for the assembly of structurally diverse scaffolds...

  8. Scaffolding Mathematical Modelling with a Solution Plan

    Science.gov (United States)

    Schukajlow, Stanislaw; Kolter, Jana; Blum, Werner

    2015-01-01

    In the study presented in this paper, we examined the possibility to scaffold mathematical modelling with strategies. The strategies were prompted using an instrument called "solution plan" as a scaffold. The effects of this step by step instrument on mathematical modelling competency and on self-reported strategies were tested using…

  9. Information Scaffolding: Application to Technical Animation

    Science.gov (United States)

    Newman, Catherine Claire

    2010-01-01

    Information Scaffolding is a user-centered approach to information design; a method devised to aid "everyday" authors in information composition. Information Scaffolding places a premium on audience-centered documents by emphasizing the information needs and motivations of a multimedia document's intended audience. The aim of this…

  10. Teaching language teachers scaffolding professional learning

    CERN Document Server

    Maggioli, Gabriel Diaz

    2012-01-01

    Teaching Language Teachers: Scaffolding Professional Learning provides an updated view of as well as a reader-friendly introduction to the field of Teaching Teachers, with special reference to language teaching. By taking a decidedly Sociocultural perspective, the book addresses the main role of the Teacher of Teachers (ToT) as that of scaffolding the professional learning of aspiring teachers.

  11. Composite scaffolds for cartilage tissue engineering.

    Science.gov (United States)

    Moutos, Franklin T; Guilak, Farshid

    2008-01-01

    Tissue engineering remains a promising therapeutic strategy for the repair or regeneration of diseased or damaged tissues. Previous approaches have typically focused on combining cells and bioactive molecules (e.g., growth factors, cytokines and DNA fragments) with a biomaterial scaffold that functions as a template to control the geometry of the newly formed tissue, while facilitating the attachment, proliferation, and differentiation of embedded cells. Biomaterial scaffolds also play a crucial role in determining the functional properties of engineered tissues, including biomechanical characteristics such as inhomogeneity, anisotropy, nonlinearity or viscoelasticity. While single-phase, homogeneous materials have been used extensively to create numerous types of tissue constructs, there continue to be significant challenges in the development of scaffolds that can provide the functional properties of load-bearing tissues such as articular cartilage. In an attempt to create more complex scaffolds that promote the regeneration of functional engineered tissues, composite scaffolds comprising two or more distinct materials have been developed. This paper reviews various studies on the development and testing of composite scaffolds for the tissue engineering of articular cartilage, using techniques such as embedded fibers and textiles for reinforcement, embedded solid structures, multi-layered designs, or three-dimensionally woven composite materials. In many cases, the use of composite scaffolds can provide unique biomechanical and biological properties for the development of functional tissue engineering scaffolds.

  12. Teaching Writing: A Multilayered Participatory Scaffolding Practice

    Science.gov (United States)

    Dix, Stephanie

    2016-01-01

    This article adds to the research on teachers' writing pedagogy. It reviews and challenges the research literature on scaffolding as an instructional practice and presents a more inclusive framework for analysis. As student participation and voice were absent from much of the literature, a participatory scaffolding framework was developed to…

  13. In vitro evaluation of the biological performance of macro/micro-porous silk fibroin and silk-nano calcium phosphate scaffolds.

    Science.gov (United States)

    Yan, L-P; Oliveira, J M; Oliveira, A L; Reis, R L

    2015-05-01

    This study evaluates the biological performance of salt-leached macro/microporous silk scaffolds (S16) and silk-nano calcium phosphate scaffolds (SC16), both deriving from a 16 wt % aqueous SF solution. Enzymatic degradation results showed that the silk-based scaffolds presented desirable biostability, and the incorporation of calcium phosphate further improved the scaffolds' biostability. Human adipose tissue derived stromal cells (hASCs) were cultured onto the scaffolds in vitro. The Alamar blue assay and DNA content revealed that both scaffolds were non-cytotoxic and can support the viability and proliferation of the hASCs. Scanning electron microscopy observation demonstrated that the microporous structure was beneficial for the cell adhesion while the macroporous structure favored the cell migration and proliferation. The histological analysis displayed abundant extracellular matrix formed inside the scaffolds, leading to the significant increase of scaffolds' modulus. These results revealed that S16 and SC16 could be promising alternatives for cartilage and bone tissue engineering scaffolding applications, respectively.

  14. Nanofibrous scaffolds for dental and craniofacial applications.

    Science.gov (United States)

    Gupte, M J; Ma, P X

    2012-03-01

    Tissue-engineering solutions often harness biomimetic materials to support cells for functional tissue regeneration. Three-dimensional scaffolds can create a multi-scale environment capable of facilitating cell adhesion, proliferation, and differentiation. One such multi-scale scaffold incorporates nanofibrous features to mimic the extracellular matrix along with a porous network for the regeneration of a variety of tissues. This review will discuss nanofibrous scaffold synthesis/fabrication, biological effects of nanofibers, their tissue- engineering applications in bone, cartilage, enamel, dentin, and periodontium, patient-specific scaffolds, and incorporated growth factor delivery systems. Nanofibrous scaffolds cannot only further the field of craniofacial regeneration but also advance technology for tissue-engineered replacements in many physiological systems.

  15. Functional Electrospun Nanofibrous Scaffolds for Biomedical Applications

    Science.gov (United States)

    Liang, Dehai; Hsiao, Benjamin S.; Chu, Benjamin

    2009-01-01

    Functional nanofibrous scaffolds produced by electrospinning have great potential in many biomedical applications, such as tissue engineering, wound dressing, enzyme immobilization and drug (gene) delivery. For a specific successful application, the chemical, physical and biological properties of electrospun scaffolds should be adjusted to match the environment by using a combination of multi-component compositions and fabrication techniques where electrospinning has often become a pivotal tool. The property of the nanofibrous scaffold can be further improved with innovative development in electrospinning processes, such as two-component electrospinning and in-situ mixing electrospinning. Post modifications of electrospun membranes also provide effective means to render the electrospun scaffolds with controlled anisotropy and porosity. In this review, we review the materials, techniques and post modification methods to functionalize electrospun nanofibrous scaffolds suitable for biomedical applications. PMID:17884240

  16. Left Atrial Appendage Closure Device With Delivery System: A Health Technology Assessment

    Science.gov (United States)

    Nevis, Immaculate; Falk, Lindsey; Wells, David; Higgins, Caroline

    2017-01-01

    Background Atrial fibrillation is a common cardiac arrhythmia, and 15% to 20% of those who have experienced stroke have atrial fibrillation. Treatment options to prevent stroke in people with atrial fibrillation include pharmacological agents such as novel oral anticoagulants or nonpharmacological devices such as the left atrial appendage closure device with delivery system (LAAC device). The objectives of this health technology assessment were to assess the clinical effectiveness and cost-effectiveness of the LAAC device versus novel oral anticoagulants in patients without contraindications to oral anticoagulants and versus antiplatelet agents in patients with contraindications to oral anticoagulants. Methods We performed a systematic review and network meta-analysis. We also conducted an economic literature review, economic evaluation, and budget impact analysis to assess the cost-effectiveness and budget impact of the LAAC device compared with novel oral anticoagulants and oral antiplatelet agents (e.g., aspirin). We also spoke with patients to better understand their preferences, perspectives, and values. Results Seven randomized controlled studies met the inclusion criteria for indirect comparison. Five studies assessed the effectiveness of novel oral anticoagulants versus warfarin, and two studies compared the LAAC device with warfarin. No studies were identified that compared the LAAC device with aspirin in patients in whom oral anticoagulants were contraindicated. Using the random effects model, we found that the LAAC device was comparable to novel oral anticoagulants in reducing stroke (odds ratio [OR] 0.85; credible interval [Cr.I] 0.63–1.05). Similarly, the reduction in the risk of all-cause mortality was comparable between the LAAC device and novel oral anticoagulants (OR 0.71; Cr.I 0.49–1.22). The LAAC device was found to be superior to novel oral anticoagulants in preventing hemorrhagic stroke (OR 0.45; Cr.I 0.29–0.79), whereas novel oral

  17. Alternative wastewatersystems

    DEFF Research Database (Denmark)

    Dyck-Madsen, Søren; Hoffmann, Birgitte; Gabriel, Søren

    1999-01-01

    The report:-  Communicates experiences from Swedish buildings from the establishment and running of alternative wastewater systems. Communicates pictures of alternative buildings and wastewater systems in Sweden. Gives a short evaluation of the performance and the sustainability of the systems....

  18. Preparation and Characterization of PDLLA/ Chondroitin Sulfate/Chitosan Scaffold for Peripheral Nerve Regeneration

    Institute of Scientific and Technical Information of China (English)

    XU Haixing; YAN Yuhua; WAN Tao; LI Shipu

    2008-01-01

    A novel bioactive and bioresorbable PDLLA/chondroitin sulfate/chitosan scaffold was prepared via layer-by-layer(LBL) electrostatic-self-assembly (ESA) and the thermally induced phase separation (TIPS) technique. Chondroitin sulfate and chitosan were alternately deposited on the activated PDLLA substrate.The deposition process was monitored by UV-Vis absorbance spectroscopy. After frozen and lyophilized, the scaffold was characterized by attenuated total reflection (ATR)-FT-IR, XPS, SEM and AFM. The results showed that the scaffold was modified uniformly with a dense inner layer with few detectable pores and a porous sponge outer layer with the pore size about 5 μm, there was an obvious across section and the average thickness of each layer was about 9.4 nm.

  19. Nanomaterial scaffolds for stem cell proliferation and differentiation in tissue engineering.

    Science.gov (United States)

    Zhao, Chunyan; Tan, Aaron; Pastorin, Giorgia; Ho, Han Kiat

    2013-01-01

    Tissue engineering is a clinically driven field and has emerged as a potential alternative to organ transplantation. The cornerstone of successful tissue engineering rests upon two essential elements: cells and scaffolds. Recently, it was found that stem cells have unique capabilities of self-renewal and multilineage differentiation to serve as a versatile cell source, while nanomaterials have lately emerged as promising candidates in producing scaffolds able to better mimic the nanostructure in natural extracellular matrix and to efficiently replace defective tissues. This article, therefore, reviews the key developments in tissue engineering, where the combination of stem cells and nanomaterial scaffolds has been utilized over the past several years. We consider the high potential, as well as the main issues related to the application of stem cells and nanomaterial scaffolds for a range of tissues including bone, cartilage, nerve, liver, eye etc. Promising in vitro results such as efficient attachment, proliferation and differentiation of stem cells have been compiled in a series of examples involving different nanomaterials. Furthermore, the merits of the marriage of stem cells and nanomaterial scaffolds are also demonstrated in vivo, providing early successes to support subsequent clinical investigations. This progress simultaneously drives mechanistic research into the mechanotransduction process responsible for the observations in order to optimize the process further. Current understanding is chiefly reported to involve the interaction of stem cells and the anchoring nanomaterial scaffolds by activating various signaling pathways. Substrate surface characteristics and scaffold bulk properties are also reported to influence not only short term stem cell adhesion, spreading and proliferation, but also longer term lineage differentiation, functionalization and viability. It is expected that the combination of stem cells and nanomaterials will develop into an

  20. Production and characterization of chitosan/gelatin/β-TCP scaffolds for improved bone tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Serra, I.R.; Fradique, R.; Vallejo, M.C.S.; Correia, T.R.; Miguel, S.P.; Correia, I.J., E-mail: icorreia@ubi.pt

    2015-10-01

    Recently, bone tissue engineering emerged as a viable therapeutic alternative, comprising bone implants and new personalized scaffolds to be used in bone replacement and regeneration. In this study, biocompatible scaffolds were produced by freeze-drying, using different formulations (chitosan, chitosan/gelatin, chitosan/β-TCP and chitosan/gelatin/β-TCP) to be used as temporary templates during bone tissue regeneration. Sample characterization was performed through attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction and energy dispersive spectroscopy analysis. Mechanical characterization and porosity analysis were performed through uniaxial compression test and liquid displacement method, respectively. In vitro studies were also done to evaluate the biomineralization activity and the cytotoxic profile of the scaffolds. Scanning electron and confocal microscopy analysis were used to study cell adhesion and proliferation at the scaffold surface and within their structure. Moreover, the antibacterial activity of the scaffolds was also evaluated through the agar diffusion method. Overall, the results obtained revealed that the produced scaffolds are bioactive and biocompatible, allow cell internalization and show antimicrobial activity against Staphylococcus aureus. Such, make these 3D structures as potential candidates for being used on the bone tissue regeneration, since they promote cell adhesion and proliferation and also prevent biofilm development at their surfaces, which is usually the main cause of implant failure. - Highlights: • Production of 3D scaffolds composed by chitosan/gelatin/β-TCP by freeze-drying for bone regeneration • Physicochemical characterization of the bone substitutes by SEM, FTIR, XRD and EDS • Evaluation of the cytotoxic profile and antibacterial activity of the 3D structures through in vitro assays.

  1. Electrospun vascular scaffold for cellularized small diameter blood vessels: A preclinical large animal study.

    Science.gov (United States)

    Ju, Young Min; Ahn, Hyunhee; Arenas-Herrera, Juan; Kim, Cheil; Abolbashari, Mehran; Atala, Anthony; Yoo, James J; Lee, Sang Jin

    2017-09-01

    The strategy of vascular tissue engineering is to create a vascular substitute by combining autologous vascular cells with a tubular-shaped biodegradable scaffold. We have previously developed a novel electrospun bilayered vascular scaffold that provides proper biological and biomechanical properties as well as structural configuration. In this study, we investigated the clinical feasibility of a cellularized vascular scaffold in a preclinical large animal model. We fabricated the cellularized vascular construct with autologous endothelial progenitor cell (EPC)-derived endothelial cells (ECs) and smooth muscle cells (SMCs) followed by a pulsatile bioreactor preconditioning. This fully cellularized vascular construct was tested in a sheep carotid arterial interposition model. After preconditioning, confluent and mature EC and SMC layers in the scaffold were achieved. The cellularized constructs sustained the structural integrity with a high degree of graft patency without eliciting an inflammatory response over the course of the 6-month period in sheep. Moreover, the matured EC coverage on the lumen and a thick smooth muscle layer were formed at 6months after transplantation. We demonstrated that electrospun bilayered vascular scaffolds in conjunction with autologous vascular cells may be a clinically applicable alternative to traditional prosthetic vascular graft substitutes. This study demonstrates the utility of tissue engineering to provide platform technologies for rehabilitation of patients recovering from severe, devastating cardiovascular diseases. The long-term goal is to provide alternatives to vascular grafting using bioengineered blood vessels derived from an autologous cell source with a functionalized vascular scaffold. This novel bilayered vascular construct for engineering blood vessels is designed to offer "off-the-shelf" availability for clinical translation. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  2. Living artificial heart valve alternatives: a review

    Directory of Open Access Journals (Sweden)

    Flanagan T. C.

    2003-11-01

    Full Text Available Conventional replacement therapies for heart valve disease are associated with significant drawbacks. The field of tissue engineering has emerged as an exciting alternative in the search for improved heart valve replacement structures. One of the principles behind this concept is the transplantation of living elements, embedded in a suitable scaffold material, to the diseased site where the structure becomes integrated with patients' tissue to restore natural function. Significant progress has been made in the last ten years in the development of a living artificial heart valve alternative (LAHVA, with the identification of potential replacement sources for valve cells, scaffolds to maintain the cells in a three-dimensional environment, and signals to promote tissue development. This review addresses the need for a tissue-engineered alternative to current prostheses and provides a detailed account of normal heart valve structure - the blueprint for LAHVA fabrication. The research efforts to create a viable LAHVA, including recent developments, are discussed. Particular attention is focused on the choice of cell source for LAHVA construction, the use of biodegradable natural and synthetic polymeric scaffolds as extracellular matrix derivatives, and exogenous stimulation of tissue growth. The critical challenges involved in LAHVA development and possible future areas of investigation are also discussed.

  3. Multilayer scaffolds in orthopaedic tissue engineering.

    Science.gov (United States)

    Atesok, Kivanc; Doral, M Nedim; Karlsson, Jon; Egol, Kenneth A; Jazrawi, Laith M; Coelho, Paulo G; Martinez, Amaury; Matsumoto, Tomoyuki; Owens, Brett D; Ochi, Mitsuo; Hurwitz, Shepard R; Atala, Anthony; Fu, Freddie H; Lu, Helen H; Rodeo, Scott A

    2016-07-01

    The purpose of this study was to summarize the recent developments in the field of tissue engineering as they relate to multilayer scaffold designs in musculoskeletal regeneration. Clinical and basic research studies that highlight the current knowledge and potential future applications of the multilayer scaffolds in orthopaedic tissue engineering were evaluated and the best evidence collected. Studies were divided into three main categories based on tissue types and interfaces for which multilayer scaffolds were used to regenerate: bone, osteochondral junction and tendon-to-bone interfaces. In vitro and in vivo studies indicate that the use of stratified scaffolds composed of multiple layers with distinct compositions for regeneration of distinct tissue types within the same scaffold and anatomic location is feasible. This emerging tissue engineering approach has potential applications in regeneration of bone defects, osteochondral lesions and tendon-to-bone interfaces with successful basic research findings that encourage clinical applications. Present data supporting the advantages of the use of multilayer scaffolds as an emerging strategy in musculoskeletal tissue engineering are promising, however, still limited. Positive impacts of the use of next generation scaffolds in orthopaedic tissue engineering can be expected in terms of decreasing the invasiveness of current grafting techniques used for reconstruction of bone and osteochondral defects, and tendon-to-bone interfaces in near future.

  4. Titanate nanotube coatings on biodegradable photopolymer scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Beke, S., E-mail: szabolcs.beke@iit.it [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Kőrösi, L. [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632, Pécs (Hungary); Scarpellini, A. [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Anjum, F.; Brandi, F. [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy)

    2013-05-01

    Rigid, biodegradable photopolymer scaffolds were coated with titanate nanotubes (TNTs) by using a spin-coating method. TNTs were synthesized by a hydrothermal process at 150 °C under 4.7 bar ambient pressure. The biodegradable photopolymer scaffolds were produced by mask-assisted excimer laser photocuring at 308 nm. For scaffold coating, a stable ethanolic TNT sol was prepared by a simple colloid chemical route without the use of any binding compounds or additives. Scanning electron microscopy along with elemental analysis revealed that the scaffolds were homogenously coated by TNTs. The developed TNT coating can further improve the surface geometry of fabricated scaffolds, and therefore it can further increase the cell adhesion. Highlights: ► Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. ► Titanate nanotube deposition was carried out without binding compounds or additives. ► The titanate nanotube coating can further improve the surface geometry of scaffolds. ► These reproducible platforms will be of high importance for biological applications.

  5. Fish collagen/alginate/chitooligosaccharides integrated scaffold for skin tissue regeneration application.

    Science.gov (United States)

    Chandika, Pathum; Ko, Seok-Chun; Oh, Gun-Woo; Heo, Seong-Yeong; Nguyen, Van-Tinh; Jeon, You-Jin; Lee, Bonggi; Jang, Chul Ho; Kim, GeunHyung; Park, Won Sun; Chang, Wonseok; Choi, Il-Whan; Jung, Won-Kyo

    2015-11-01

    An emerging paradigm in wound healing techniques is that a tissue-engineered skin substitute offers an alternative approach to create functional skin tissue. Here we developed a fish collagen/alginate (FCA) sponge scaffold that was functionalized by different molecular weights of chitooligosaccharides (COSs) with the use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as a cross-linking agent. The effects of cross-linking were analyzed by Fourier transform infrared spectroscopy. The results indicate that the homogeneous materials blending and cross-linking intensity were dependent on the molecular weights of COSs. The highly interconnected porous architecture with 160-260μm pore size and over 90% porosity and COS's MW driven swelling and retention capacity, tensile property and in vitro biodegradation behavior guaranteed the FCA/COS scaffolds for skin tissue engineering application. Further improvement of these properties enhanced the cytocompatibility of all the scaffolds, especially the scaffolds containing COSs with MW in the range of 1-3kDa (FCA/COS1) showed the best cytocompatibility. These physicochemical, mechanical, and biological properties suggest that the FCA/COS1 scaffold is a superior candidate that can be used for skin tissue regeneration.

  6. Xenogenic Esophagus Scaffolds Fixed with Several Agents: Comparative In Vivo Study of Rejection and Inflammation

    Directory of Open Access Journals (Sweden)

    Holger Koch

    2012-01-01

    Full Text Available Most infants with long-gap esophageal atresia receive an esophageal replacement with tissue from stomach or colon, because the native esophagus is too short for true primary repair. Tissue-engineered esophageal conducts could present an attractive alternative. In this paper, circular decellularized porcine esophageal scaffold tissues were implanted subcutaneously into Sprague-Dawley rats. Depending on scaffold cross-linking with genipin, glutaraldehyde, and carbodiimide (untreated scaffolds : positive control; bovine pericardium : gold standard, the number of infiltrating fibroblasts, lymphocytes, macrophages, giant cells, and capillaries was determined to quantify the host response after 1, 9, and 30 days. Decellularized esophagus scaffolds were shown to maintain native matrix morphology and extracellular matrix composition. Typical inflammatory reactions were observed in all implants; however, the cellular infiltration was reduced in the genipin group. We conclude that genipin is the most efficient and best tolerated cross-linking agent to attenuate inflammation and to improve the integration of esophageal scaffolds into its surrounding tissue after implantation.

  7. In Vivo Imaging Study of Angiogenesis in a Channelized Porous Scaffold

    Directory of Open Access Journals (Sweden)

    Margherita Tamplenizza

    2015-05-01

    Full Text Available The main scientific issue hindering the development of tissue engineering technologies is the lack of proper vascularization. Among the various approaches developed for boosting vascularization, scaffold design has attracted increasing interest over the last few years. The aim of this article is to illustrate a scaffold design strategy for enhancing vascularization based on sacrificial microfabrication of embedded microchannels. This approach was combined with an innovative poly(ether urethane urea (PEUtU porous scaffold to provide an alternative graft substitute material for the treatment of tissue defects. Fluorescent and chemiluminescent imaging combined with computed tomography were used to study the behavior of the scaffold composition within living subjects by analyzing angiogenesis and inflammation processes and observing the variation in x-ray absorption, respectively. For this purpose, an IntegriSense 680 probe was used in vivo for the localization and quantification of integrin αvβ3, due to its critical involvement in angiogenesis, and a XenoLight RediJect Inflammation Probe for the study of the decline in inflammation progression during healing. Overall, the collected data suggest the advantages of embedding a synthetic vascular network into a PEUtU porous matrix to enhance in vivo tissue integration, maturation, and regeneration. Moreover, our imaging approach proved to be an efficient and versatile tool for scaffold in vivo testing.

  8. In vivo imaging study of angiogenesis in a channelized porous scaffold.

    Science.gov (United States)

    Tamplenizza, Margherita; Tocchio, Alessandro; Gerges, Irini; Martello, Federico; Martelli, Cristina; Ottobrini, Luisa; Lucignani, Giovanni; Milani, Paolo; Lenardi, Cristina

    2015-01-01

    The main scientific issue hindering the development of tissue engineering technologies is the lack of proper vascularization. Among the various approaches developed for boosting vascularization, scaffold design has attracted increasing interest over the last few years. The aim of this article is to illustrate a scaffold design strategy for enhancing vascularization based on sacrificial microfabrication of embedded microchannels. This approach was combined with an innovative poly(ether urethane urea) (PEUtU) porous scaffold to provide an alternative graft substitute material for the treatment of tissue defects. Fluorescent and chemiluminescent imaging combined with computed tomography were used to study the behavior of the scaffold composition within living subjects by analyzing angiogenesis and inflammation processes and observing the variation in x-ray absorption, respectively. For this purpose, an IntegriSense 680 probe was used in vivo for the localization and quantification of integrin αvβ3, due to its critical involvement in angiogenesis, and a XenoLight RediJect Inflammation Probe for the study of the decline in inflammation progression during healing. Overall, the collected data suggest the advantages of embedding a synthetic vascular network into a PEUtU porous matrix to enhance in vivo tissue integration, maturation, and regeneration. Moreover, our imaging approach proved to be an efficient and versatile tool for scaffold in vivo testing.

  9. Scaffolding for Argumentation in Hypothetical and Theoretical Biology Concepts

    Science.gov (United States)

    Weng, Wan-Yun; Lin, Yu-Ren; She, Hsiao-Ching

    2017-01-01

    The present study investigated the effects of online argumentation scaffolding on students' argumentation involving hypothetical and theoretical biological concepts. Two types of scaffolding were developed in order to improve student argumentation: continuous scaffolding and withdraw scaffolding. A quasi-experimental design was used with four…

  10. Examinations of a new long-term degradable electrospun polycaprolactone scaffold in three rat abdominal wall models.

    Science.gov (United States)

    Jangö, Hanna; Gräs, Søren; Christensen, Lise; Lose, Gunnar

    2017-02-01

    Alternative approaches to reinforce native tissue in reconstructive surgery for pelvic organ prolapse are warranted. Tissue engineering combines the use of a scaffold with the regenerative potential of stem cells and is a promising new concept in urogynecology. Our objective was to evaluate whether a newly developed long-term degradable polycaprolactone scaffold could provide biomechanical reinforcement and function as a scaffold for autologous muscle fiber fragments. We performed a study with three different rat abdominal wall models where the scaffold with or without muscle fiber fragments was placed (1) subcutaneously (minimal load), (2) in a partial defect (partial load), and (3) in a full-thickness defect (heavy load). After 8 weeks, no animals had developed hernia, and the scaffold provided biomechanical reinforcement, even in the models where it was subjected to heavy load. The scaffold was not yet degraded but showed increased thickness in all groups. Histologically, we found a massive foreign body response with numerous large giant cells intermingled with the fibers of the scaffold. Cells from added muscle fiber fragments could not be traced by PKH26 fluorescence or desmin staining. Taken together, the long-term degradable polycaprolactone scaffold provided biomechanical reinforcement by inducing a marked foreign-body response and attracting numerous inflammatory cells to form a strong neo-tissue construct. However, cells from the muscle fiber fragments did not survive in this milieu. Properties of the new neo-tissue construct must be evaluated at the time of full degradation of the scaffold before its possible clinical value in pelvic organ prolapse surgery can be evaluated.

  11. Locomotion Dynamics for Bio-inspired Robots with Soft Appendages: Application to Flapping Flight and Passive Swimming

    Science.gov (United States)

    Boyer, Frédéric; Porez, Mathieu; Morsli, Ferhat; Morel, Yannick

    2017-08-01

    In animal locomotion, either in fish or flying insects, the use of flexible terminal organs or appendages greatly improves the performance of locomotion (thrust and lift). In this article, we propose a general unified framework for modeling and simulating the (bio-inspired) locomotion of robots using soft organs. The proposed approach is based on the model of Mobile Multibody Systems (MMS). The distributed flexibilities are modeled according to two major approaches: the Floating Frame Approach (FFA) and the Geometrically Exact Approach (GEA). Encompassing these two approaches in the Newton-Euler modeling formalism of robotics, this article proposes a unique modeling framework suited to the fast numerical integration of the dynamics of a MMS in both the FFA and the GEA. This general framework is applied on two illustrative examples drawn from bio-inspired locomotion: the passive swimming in von Karman Vortex Street, and the hovering flight with flexible flapping wings.

  12. Left atrial appendage thrombus with resulting stroke post-RF ablation for atrial fibrillation in a patient on dabigatran.

    LENUS (Irish Health Repository)

    Lobo, R

    2015-11-01

    Dabigatran etexilate is licensed for use in prevention of deep venous thromboembolism and in prevention of stroke and systemic embolism in nonvalvular atrial fibrillation (AF). It has also been used in patients for other indications as a substitute for warfarin therapy because it requires no monitoring; one group being patients undergoing radiofrequency (RF), ablation for AF, although there have been no consensus guidelines with regards to dosage and timing of dose. We report the case of a patient with documentary evidence of left atrial appendage (LAA) thrombus formation and neurological sequelae post-RF ablation despite being on dabigatran. This case highlights the concern that periprocedural dabigatran may not provide adequate protection from development of LAA thrombus and that a standardised protocol will need to be developed and undergo large multicentre trials before dabigatran can be safely used for patients undergoing RF-ablation.

  13. The dynamics and optimal control of spinning spacecraft with movable telescoping appendages. Part C: Effect of flexibility during boom deployment

    Science.gov (United States)

    Bainum, P. M.; James, P. K.

    1977-01-01

    The dynamics of a spinning symmetrical spacecraft system during the deployment (or retraction) of flexible boom-type appendages were investigated. The effect of flexibility during boom deployment is treated by modelling the deployable members as compound spherical pendula of varying length (according to a control law). The orientation of the flexible booms with respect to the hub, is described by a sequence of two Euler angles. The boom members contain a flexural stiffness which can be related to an assumed effective restoring linear spring constant, and structural damping which effects the entire system. Linearized equations of motion for this system, when the boom length is constant, involve periodic coefficients with the frequency of the hub spin. A bounded transformation is found which converts this system into a kinematically equivalent one involving only constant coefficients.

  14. Echocardiographic guidance and monitoring of left atrial appendage closure with AtriClip during open-chest cardiac surgery.

    Science.gov (United States)

    Contri, Rachele; Clivio, Sara; Torre, Tiziano; Cassina, Tiziano

    2017-09-12

    Left atrial appendage (LAA) closure prevents thromboembolic risk and avoids lifelong anticoagulation due to atrial fibrillation (AF). Nowadays, AtriClip, a modern epicardial device approved in June 2010, allows external and safe closure of LAA in patients undergoing cardiac surgery during other open-chest cardiac surgical procedures. Such a surgical approach and its epicardial deployment differentiates LAA closure with AtriClip from percutaneous closure techniques such as Watchman (Boston Scientific, Marlborough, MA, USA), Lariat (SentreHEART Inc., Redwood City, CA, USA), and Amplatzer Amulet (St. Jude Medical, St. Paul, MN, USA) device procedures. AtriClip positioning must consider perioperative transesophageal echocardiography (TEE) to confirm LAA anatomical features, to explore the links with neighboring structures, and finally to assess its successful closure. We report a sequence of images to document the role of intraoperative TEE during an elective aortic valve replacement and LAA external closure with AtriClip. © 2017, Wiley Periodicals, Inc.

  15. Alternative metrics

    Science.gov (United States)

    2012-11-01

    As the old 'publish or perish' adage is brought into question, additional research-impact indices, known as altmetrics, are offering new evaluation alternatives. But such metrics may need to adjust to the evolution of science publishing.

  16. Hox genes require homothorax and extradenticle for body wall identity specification but not for appendage identity specification during metamorphosis of Tribolium castaneum.

    Science.gov (United States)

    Smith, Frank W; Jockusch, Elizabeth L

    2014-11-01

    The establishment of segment identity is a key developmental process that allows for divergence along the anteroposterior body axis in arthropods. In Drosophila, the identity of a segment is determined by the complement of Hox genes it expresses. In many contexts, Hox transcription factors require the protein products of extradenticle (exd) and homothorax (hth) as cofactors to perform their identity specification functions. In holometabolous insects, segment identity may be specified twice, during embryogenesis and metamorphosis. To glean insight into the relationship between embryonic and metamorphic segmental identity specification, we have compared these processes in the flour beetle Tribolium castaneum, which develops ventral appendages during embryogenesis that later metamorphose into adult appendages with distinct morphologies. At metamorphosis, comparisons of RNAi phenotypes indicate that Hox genes function jointly with Tc-hth and Tc-exd to specify several region-specific aspects of the adult body wall. On the other hand, Hox genes specify appendage identities along the anteroposterior axis independently of Tc-hth/Tc-exd and Tc-hth/Tc-exd specify proximal vs. distal identity within appendages independently of Hox genes during this stage. During embryogenesis, Tc-hth and Tc-exd play a broad role in the segmentation process and are required for specification of body wall identities in the thorax; however, contrasting with results from other species, we did not obtain homeotic transformations of embryonic appendages in response to Tc-hth or Tc-exd RNAi. In general, the homeotic effects of interference with the function of Hox genes and Tc-hth/Tc-exd during metamorphosis did not match predictions based on embryonic roles of these genes. Comparing metamorphic patterning in T. castaneum to embryonic and post-embryonic development in hemimetabolous insects suggests that holometabolous metamorphosis combines patterning processes of both late embryogenesis and

  17. Evolution of Chemosensory Gene Families in Arthropods: Insight from the First Inclusive Comparative Transcriptome Analysis across Spider Appendages

    Science.gov (United States)

    Vizueta, Joel; Frías-López, Cristina; Macías-Hernández, Nuria; Arnedo, Miquel A.

    2017-01-01

    Unlike hexapods and vertebrates, in chelicerates, knowledge of the specific molecules involved in chemoreception comes exclusively from the comparative analysis of genome sequences. Indeed, the genomes of mites, ticks and spiders contain several genes encoding homologs of some insect membrane receptors and small soluble chemosensory proteins. Here, we conducted for the first time a comprehensive comparative RNA-Seq analysis across different body structures of a chelicerate: the nocturnal wandering hunter spider Dysdera silvatica Schmidt 1981. Specifically, we obtained the complete transcriptome of this species as well as the specific expression profile in the first pair of legs and the palps, which are thought to be the specific olfactory appendages in spiders, and in the remaining legs, which also have hairs that have been morphologically identified as chemosensory. We identified several ionotropic (Ir) and gustatory (Gr) receptor family members exclusively or differentially expressed across transcriptomes, some exhibiting a distinctive pattern in the putative olfactory appendages. Furthermore, these IRs were the only known olfactory receptors identified in such structures. These results, integrated with an extensive phylogenetic analysis across arthropods, uncover a specialization of the chemosensory gene repertoire across the body of D. silvatica and suggest that some IRs likely mediate olfactory signaling in chelicerates. Noticeably, we detected the expression of a gene family distantly related to insect odorant-binding proteins (OBPs), suggesting that this gene family is more ancient than previously believed, as well as the expression of an uncharacterized gene family encoding small globular secreted proteins, which appears to be a good chemosensory gene family candidate. PMID:28028122

  18. Mother Centriole Distal Appendages Mediate Centrosome Docking at the Immunological Synapse and Reveal Mechanistic Parallels with Ciliogenesis.

    Science.gov (United States)

    Stinchcombe, Jane C; Randzavola, Lyra O; Angus, Karen L; Mantell, Judith M; Verkade, Paul; Griffiths, Gillian M

    2015-12-21

    Cytotoxic T lymphocytes (CTLs) are highly effective serial killers capable of destroying virally infected and cancerous targets by polarized release from secretory lysosomes. Upon target contact, the CTL centrosome rapidly moves to the immunological synapse, focusing microtubule-directed release at this point [1-3]. Striking similarities have been noted between centrosome polarization at the synapse and basal body docking during ciliogenesis [1, 4-8], suggesting that CTL centrosomes might dock with the plasma membrane during killing, in a manner analogous to primary cilia formation [1, 4]. However, questions remain regarding the extent and function of centrosome polarization at the synapse, and recent reports have challenged its role [9, 10]. Here, we use high-resolution transmission electron microscopy (TEM) tomography analysis to show that, as in ciliogenesis, the distal appendages of the CTL mother centriole contact the plasma membrane directly during synapse formation. This is functionally important as small interfering RNA (siRNA) targeting of the distal appendage protein, Cep83, required for membrane contact during ciliogenesis [11], impairs CTL secretion. Furthermore, the regulatory proteins CP110 and Cep97, which must dissociate from the mother centriole to allow cilia formation [12], remain associated with the mother centriole in CTLs, and neither axoneme nor transition zone ciliary structures form. Moreover, complete centrosome docking can occur in proliferating CTLs with multiple centriole pairs. Thus, in CTLs, centrosomes dock transiently with the membrane, within the cell cycle and without progression into ciliogenesis. We propose that this transient centrosome docking without cilia formation is important for CTLs to deliver rapid, repeated polarized secretion directed by the centrosome.

  19. Semiotic Scaffolding in Living Systems

    DEFF Research Database (Denmark)

    Hoffmeyer, Jesper

    2008-01-01

    The apparently purposeful nature of living systems is obtained through a sophisticated network of semiotic controls whereby biochemical, physiological and behavioral processes become tuned to the needs of the system. The operation of these semiotic controls takes place and is enabled across...... a diversity of levels. Such semiotic controls may be distinguished from ordinary deterministic control mechanisms through an inbuilt anticipatory capacity based on a distinct kind of causation that I call here "semiotic causation" to denote the bringing about of changes under the guidance of interpretation...... in a local .context. Anticipation through the skilled interpretation of indicators of temporal relations in the context of a particular survival project (or life strategy) guides organismic behavior towards local ends. This network of semiotic controls establishes an enormously complex semiotic scaffolding...

  20. Scaffolding With and Through Videos

    DEFF Research Database (Denmark)

    Otrel-Cass, Kathrin; Khoo, Elaine; Cowie, Bronwen

    2012-01-01

    In New Zealand and internationally claims are being made about the potential for information and communication technologies (ICTs) to transform teaching and learning. However, the theoretical underpinnings explaining the complex interplay between the content, pedagogy and technology a teacher needs...... to consider must be expanded. This article explicates theoretical and practical ideas related to teachers’ application of their ICT technology, pedagogy, and content knowledge (TPACK) in science. The article unpacks the social and technological dimensions of teachers’ use of TPACK when they use digital videos...... to scaffold learning. It showcases the intricate interplay between teachers’ knowledge about content, digital video technology, and students’ learning needs based on a qualitative study of two science teachers and their students in a New Zealand primary school....

  1. Analytical and experimental bearing capacities of system scaffolds

    Institute of Scientific and Technical Information of China (English)

    Jui-lin PENG; Tsong YEN; Ching-chi KUO; Siu-lai CHAN

    2009-01-01

    We investigated the structural behavior and bearing capacity of system scaffolds. The research showed that the critical load of a system scaffold structure without diagonal braces is similar to that of a door-shaped steel scaffold structure. Joint stiffness between vertical props in system scaffolds can be defined based on a comparison between analytical and experimental results. When the number of scaffold stories increases, the critical loads of system scaffolds decrease. Diagonal braces markedly enhance the critical load of system scaffolds. The coupling joint position between vertical props should be kept away from story-to-story joints to prevent a reduction in critical loads. The critical load of a system scaffold decreases as the quantity of extended vertical props at the bottom of the structure increases. A large Christmas tree set up by system scaffolds under various loads was used as an example for analysis and to check the design of system scaffolds.

  2. SHOP: scaffold hopping by GRID-based similarity searches

    DEFF Research Database (Denmark)

    Bergmann, Rikke; Linusson, Anna; Zamora, Ismael

    2007-01-01

    A new GRID-based method for scaffold hopping (SHOP) is presented. In a fully automatic manner, scaffolds were identified in a database based on three types of 3D-descriptors. SHOP's ability to recover scaffolds was assessed and validated by searching a database spiked with fragments of known...... ligands of three different protein targets relevant for drug discovery using a rational approach based on statistical experimental design. Five out of eight and seven out of eight thrombin scaffolds and all seven HIV protease scaffolds were recovered within the top 10 and 31 out of 31 neuraminidase...... scaffolds were in the 31 top-ranked scaffolds. SHOP also identified new scaffolds with substantially different chemotypes from the queries. Docking analysis indicated that the new scaffolds would have similar binding modes to those of the respective query scaffolds observed in X-ray structures...

  3. Osteogenic differentiation and mineralization of human exfoliated deciduous teeth stem cells on modified chitosan scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Su, Wen-Ta, E-mail: f10549@ntut.edu.tw [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan (China); Wu, Pai-Shuen [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, Taiwan (China); Ko, Chih-Sheng [PhytoHealth Corporation, Maywufa Biopharma Group, Taipei, Taiwan (China); Huang, Te-Yang [Mackay Memorial Hospital, Taipei, Taiwan (China)

    2014-08-01

    Stem cells from human exfoliated deciduous teeth (SHEDs) have been considered as alternative sources of adult stem cells in tissue engineering because of their potential to differentiate into multiple cell lineages. Strontium has an important function in bone remodeling because it can simulate bone formation and decrease bone resorption. In this study, the effects of strontium phosphate on the osteogenic differentiation of SHEDs were investigated. Strontium phosphate was found to enhance the osteogenic differentiation of SHEDs with up-regulated osteoblast-related gene expression. The proliferation of SHEDs was slightly inhibited by chitosan scaffolds; however, type-I collagen expression, alkaline phosphatase activity, and calcium deposition on chitosan scaffolds containing strontium were significantly enhanced. Furthermore, cells seeded in a 3D scaffold under dynamic culture at an optimal fluid rate might enhance cellular differentiation than static culture in osteoblastic gene expression. This experiment might provide a useful cell resource and dynamic 3D culture for tissue engineering and bone repair. - Highlights: • SHEDs have been considered as alternative sources of adult stem cells in tissue engineering • Strontium phosphate can enhance the osteogenic differentiation of SHEDs • 3D scaffold under dynamic culture with optimal fluid rate enhance cellular differentiation.

  4. Nanostructured scaffolds for bone tissue engineering.

    Science.gov (United States)

    Li, Xiaoming; Wang, Lu; Fan, Yubo; Feng, Qingling; Cui, Fu-Zhai; Watari, Fumio

    2013-08-01

    It has been demonstrated that nanostructured materials, compared with conventional materials, may promote greater amounts of specific protein interactions, thereby more efficiently stimulating new bone formation. It has also been indicated that, when features or ingredients of scaffolds are nanoscaled, a variety of interactions can be stimulated at the cellular level. Some of those interactions induce favorable cellular functions while others may leads to toxicity. This review presents the mechanism of interactions between nanoscaled materials and cells and focuses on the current research status of nanostructured scaffolds for bone tissue engineering. Firstly, the main requirements for bone tissue engineering scaffolds were discussed. Then, the mechanism by which nanoscaled materials promote new bone formation was explained, following which the current research status of main types of nanostructured scaffolds for bone tissue engineering was reviewed and discussed. Copyright © 2013 Wiley Periodicals, Inc.

  5. Scaffolding Instruction on Business English Writing Teaching

    Institute of Scientific and Technical Information of China (English)

    邱迪

    2014-01-01

    The scaffolding instruction is to help students probe into knowledge learning independently, and achieve the construction of knowledge and information finally by constructing a series of appropriate conceptual frameworks and concrete teaching circumstances. This instruction has been extensively applied and has been proved to be very effective in teaching in western countries. But in China very few empirical studies have been carried out on the scaffolding instruction, especial y in the field of teaching Business English writing.

  6. Rapid prototyped porous nickel-titanium scaffolds as bone substitutes.

    Science.gov (United States)

    Hoffmann, Waldemar; Bormann, Therese; Rossi, Antonella; Müller, Bert; Schumacher, Ralf; Martin, Ivan; de Wild, Michael; Wendt, David

    2014-01-01

    While calcium phosphate-based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel-titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel-titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel-titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel-titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel-titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel-titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold's pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel-titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used titanium.

  7. Reproducing American Sign Language Sentences: Cognitive Scaffolding in Working Memory

    Directory of Open Access Journals (Sweden)

    Ted eSupalla

    2014-08-01

    Full Text Available The American Sign Language Sentence Reproduction Test (ASL-SRT requires the precise reproduction of a series of ASL sentences increasing in complexity and length. Error analyses of such tasks provides insight into working memory and scaffolding processes. Data was collected from three groups expected to differ in fluency: deaf children, deaf adults and hearing adults, all users of ASL. Quantitative (correct/incorrect recall and qualitative error analyses were performed. Percent correct on the reproduction task supports its sensitivity to fluency as test performance clearly differed across the three groups studied. A linguistic analysis of errors further documented differing strategies and bias across groups. Subjects’ recall projected the affordance and constraints of deep linguistic representations to differing degrees, with subjects resorting to alternate processing strategies in the absence of linguistic knowledge. A qualitative error analysis allows us to capture generalizations about the relationship between error pattern and the cognitive scaffolding, which governs the sentence reproduction process. Highly fluent signers and less-fluent signers share common chokepoints on particular words in sentences. However, they diverge in heuristic strategy. Fluent signers, when they make an error, tend to preserve semantic details while altering morpho-syntactic domains. They produce syntactically correct sentences with equivalent meaning to the to-be-reproduced one, but these are not verbatim reproductions of the original sentence. In contrast, less-fluent signers tend to use a more linear strategy, preserving lexical status and word ordering while omitting local inflections, and occasionally resorting to visuo-motoric imitation. Thus, whereas fluent signers readily use top-down scaffolding in their working memory, less fluent signers fail to do so. Implications for current models of working memory across spoken and signed modalities are

  8. Scaffolds in regenerative endodontics: A review.

    Science.gov (United States)

    Gathani, Kinjal M; Raghavendra, Srinidhi Surya

    2016-09-01

    Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. 'A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria 'Platelet rich plasma', 'Platelet rich fibrin', 'Stem cells', 'Natural and artificial scaffolds' from 1982-2015'. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon.

  9. The Nanogel-Based Scaffold in Endodontics

    Science.gov (United States)

    Kheirieh, Sanam

    Aim: The purpose of this study was to evaluate a degradable nanogel-based scaffold with antibacterial content. Methods: This nanogel design consisted of the cross-linker, polyethyleneglycol (PEG 4600) with 3-dimensional network. This polymer degrades over time ( 30 days), delivering a controlled release of antibiotic. Amoxicillin was added to the scaffold with 25 wt% (n=26). Nanogel-scaffold only and amoxicillin only were used as controls. Agar diffusion test against E. faecalis was performed at eight time intervals (days 1, 3, 5, 7, 10, 14, 21, 30). One-Way ANOVA was used to compare the antibacterial properties of experimental groups at the eight different times. Results: The antibacterial properties for experimental plates, at the different times, were not significantly different (F=.624, p=.74). Based on the profile, the scaffold-only group showed a smaller inhibition zone compared to the two other groups. The antibacterial profiles for the experimental group and the antibiotic-only group were similar. Conclusion: This particular scaffold presented antibacterial properties. Findings suggest that nanogel-modified scaffolds may have potential use for drug-delivery in endodontics..

  10. Antimicrobial Cu-bearing stainless steel scaffolds.

    Science.gov (United States)

    Wang, Qiang; Ren, Ling; Li, Xiaopeng; Zhang, Shuyuan; Sercombe, Timothy B; Yang, Ke

    2016-11-01

    Copper-bearing stainless steel scaffolds with two different structures (Body Centered Cubic and Gyroid labyrinth) at two solid fractions (25% and 40%) were fabricated from both 316L powder and a mixture of 316L and elemental Cu powder using selective laser melting, and relative 316L scaffolds were served as control group. After processing, the antimicrobial testing demonstrated that the 316L-Cu scaffolds presented excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus, and the cell viability assay indicated that there was no cytotoxic effect of 316L-Cu scaffolds on rat marrow mesenchymal stem cells. As such, these have the potential to reduce implant-associated infections. The Cu was also found to homogeneously distribute within the microstructure by scanning electronic microcopy. The addition of Cu would not significantly affect its strength and stiffness compared to 316L scaffold, and the stiffness of all the scaffolds (3-20GPa) is similar to that of bone and much less than that of bulk stainless steel. Consequently, fabrication of such low stiffness porous structures, especially coupled with the addition of antimicrobial Cu, may provide a new direction for medical stainless steels.

  11. A review: fabrication of porous polyurethane scaffolds.

    Science.gov (United States)

    Janik, H; Marzec, M

    2015-03-01

    The aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical properties, ability to control the rate of degradation and similarities to natural tissue structures. Polyurethanes (PUs) are attractive candidates for scaffold fabrication, since they are biocompatible, and have excellent mechanical properties and mechanical flexibility. PU can be applied to various methods of porous scaffold fabrication, among which are solvent casting/particulate leaching, thermally induced phase separation, gas foaming, emulsion freeze-drying and melt moulding. Scaffold properties obtained by these techniques, including pore size, interconnectivity and total porosity, all depend on the thermal processing parameters, and the porogen agent and solvents used. In this review, various polyurethane systems for scaffolds are discussed, as well as methods of fabrication, including the latest developments, and their advantages and disadvantages.

  12. Methods for Producing Scaffold-Free Engineered Cartilage Sheets from Auricular and Articular Chondrocyte Cell Sources and Attachment to Porous Tantalum

    OpenAIRE

    Whitney, G. Adam; Mera, Hisashi; Weidenbecher, Mark; Awadallah, Amad; Mansour, Joseph M.; Dennis, James E.

    2012-01-01

    Abstract Scaffold-free cartilage engineering techniques may provide a simple alternative to traditional methods employing scaffolds. We previously reported auricular chondrocyte-derived constructs for use in an engineered trachea model; however, the construct generation methods were not reported in detail. In this study, methods for cartilage construct generation from auricular and articular cell sources are described in detail, and the resulting constructs are compared for use in a joint res...

  13. Signs, dispositions, and semiotic scaffolding.

    Science.gov (United States)

    Fernández, Eliseo

    2015-12-01

    scaffolding. These interactions transpire between energetic causal chains and a wide range of converging semiotic transactions unfolding within each individual organism and between organisms and their environment. The perspective advanced here helps elucidate the manner in which physical and semiotic causation cooperate in an orchestrated fashion, giving rise to an ever-expanding profusion of scaffolding structures and processes. Using simple examples I outline some mechanisms that bring about this orchestration as well as the resultant channeling activities that eventually merge and find their culmination in the enactment of goal-oriented behavior.

  14. Acute In Vivo Response to an Alternative Implant for Urogynecology

    Directory of Open Access Journals (Sweden)

    Sabiniano Roman Regueros

    2014-01-01

    Full Text Available Purpose. To investigate in vivo the acute host response to an alternative implant designed for the treatment of stress urinary incontinence (SUI and pelvic organ prolapse (POP. Methods. A biodegradable scaffold was produced from poly-L-lactic acid (PLA using the electrospinning technique. Human and rat adipose-derived stem cells (ADSCs were isolated and characterized by fluorescence-activated cell sorting and differentiation assays. PLA scaffolds were seeded and cultured for 2 weeks with human or rat ADSCs. Scaffolds with and without human or rat ADSCs were implanted subcutaneously on the abdominal wall of rats. After 3 and 7 days, 6 animals from each group were sacrificed. Sections from each sample were analyzed by Haematoxylin and Eosin staining, Sirius red staining, and immunohistochemistry for CD68, PECAM-1, and collagen I and III. Results. Animals responded to the scaffolds with an acute macrophage response. After 7 days of implantation, there was extensive host cell penetration, new blood vessel formation, and new collagen deposition throughout the full thickness of the samples without obvious differences between cell-containing and cell-free scaffolds. Conclusions. The acute in vivo response to an alternative implant (both with and without cells for the treatment of SUI and POP showed good acute integration into the host tissues.

  15. Alternative Veier

    DEFF Research Database (Denmark)

    Kruse, Tove Elisabeth; Salamonsen, Anita

    reflektioner omkring patienters brug af og erfaringer med alternativ behandling. Patientorganisationer, organisatoner for alternative behandlere og organisationer for læger og medicinstuderende har læst bogens patienthistorier og deres perspektiver lægges frem. Til slut i bogen diskuteres betydningen af de...

  16. Growing Alternatives

    DEFF Research Database (Denmark)

    Bagger-Petersen, Mai Corlin

    2014-01-01

    From 2014, Anhui Province will pilot a reform of the residential land market in China, thus integrating rural Anhui in the national housing market. In contrast, artist and activist Ou Ning has proposed the Bishan time money currency, intending to establish an alternative economic circuit in Bishan...

  17. Magnetostrictive Alternator

    Science.gov (United States)

    Dyson, Rodger; Bruder, Geoffrey

    2013-01-01

    This innovation replaces the linear alternator presently used in Stirling engines with a continuous-gradient, impedance-matched, oscillating magnetostrictive transducer that eliminates all moving parts via compression, maintains high efficiency, costs less to manufacture, reduces mass, and eliminates the need for a bearing system. The key components of this new technology are the use of stacked magnetostrictive materials, such as Terfenol-D, under a biased magnetic and stress-induced compression, continuous-gradient impedance-matching material, coils, force-focusing metallic structure, and supports. The acoustic energy from the engine travels through an impedancematching layer that is physically connected to the magnetostrictive mass. Compression bolts keep the structure under compressive strain, allowing for the micron-scale compression of the magnetostrictive material and eliminating the need for bearings. The relatively large millimeter displacement of the pressure side of the impedance-matching material is reduced to micron motion, and undergoes stress amplification at the magnetostrictive interface. The alternating compression and expansion of the magnetostrictive material creates an alternating magnetic field that then induces an electric current in a coil that is wound around the stack. This produces electrical power from the acoustic pressure wave and, if the resonant frequency is tuned to match the engine, can replace the linear alternator that is commonly used.

  18. Alternative Treatments

    Science.gov (United States)

    ... triglyceride (fat) produced by processing coconut oil or palm kernel oil. The body breaks down caprylic acid into substances called “ketone bodies.” The theory behind Axona is that the ketone bodies derived from caprylic acid may provide an alternative energy source for brain cells that have lost ...

  19. A nano-sandwich construct built with graphene nanosheets and carbon nanotubes enhances mechanical properties of hydroxyapatite-polyetheretherketone scaffolds.

    Science.gov (United States)

    Feng, Pei; Peng, Shuping; Wu, Ping; Gao, Chengde; Huang, Wei; Deng, Youwen; Xiao, Tao; Shuai, Cijun

    2016-01-01

    A nano-sandwich construct was built by combining two-dimensional graphene nanosheets (GNSs) and one-dimensional carbon nanotubes (CNTs) to improve the mechanical properties of hydroxyapatite-polyetheretherketone (HAP-PEEK) scaffolds for bone tissue engineering. In this nano-sandwich construct, the long tubular CNTs penetrated the interlayers of graphene and prevented their aggregation, increasing the effective contact area between the construct and matrix. The combination of GNSs and CNTs in a weight ratio of 2:8 facilitated the dispersion of each other and provided a synergetic effect in enhancing the mechanical properties. The compressive strength and modulus of the scaffolds were increased by 63.58% and 56.54% at this time compared with those of HAP-PEEK scaffolds, respectively. The carbon-based fillers, pulling out and bridging, were also clearly observed in the matrix. Moreover, the dangling of CNTs and their entangling with GNSs further reinforced the mechanical properties. Furthermore, apatite layer formed on the scaffold surface after immersing in simulated body fluid, and the cells attached and spread well on the surface of the scaffolds and displayed good viability, proliferation, and differentiation. These evidence indicate that the HAP-PEEK scaffolds enhanced by GNSs and CNTs are a promising alternative for bone tissue engineering.

  20. Mechanical behaviour of a fibrous scaffold for ligament tissue engineering: finite elements analysis vs. X-ray tomography imaging.

    Science.gov (United States)

    Laurent, Cédric P; Latil, Pierre; Durville, Damien; Rahouadj, Rachid; Geindreau, Christian; Orgéas, Laurent; Ganghoffer, Jean-François

    2014-12-01

    The use of biodegradable scaffolds seeded with cells in order to regenerate functional tissue-engineered substitutes offers interesting alternative to common medical approaches for ligament repair. Particularly, finite element (FE) method enables the ability to predict and optimise both the macroscopic behaviour of these scaffolds and the local mechanic signals that control the cell activity. In this study, we investigate the ability of a dedicated FE code to predict the geometrical evolution of a new braided and biodegradable polymer scaffold for ligament tissue engineering by comparing scaffold geometries issued from FE simulations and from X-ray tomographic imaging during a tensile test. Moreover, we compare two types of FE simulations the initial geometries of which are issued either from X-ray imaging or from a computed idealised configuration. We report that the dedicated FE simulations from an idealised reference configuration can be reasonably used in the future to predict the global and local mechanical behaviour of the braided scaffold. A valuable and original dialog between the fields of experimental and numerical characterisation of such fibrous media is thus achieved. In the future, this approach should enable to improve accurate characterisation of local and global behaviour of tissue-engineering scaffolds.

  1. Tri-Layered Nanocomposite Hydrogel Scaffold for the Concurrent Regeneration of Cementum, Periodontal Ligament, and Alveolar Bone.

    Science.gov (United States)

    Sowmya, S; Mony, Ullas; Jayachandran, P; Reshma, S; Kumar, R Arun; Arzate, H; Nair, Shantikumar V; Jayakumar, R

    2017-04-01

    A tri-layered scaffolding approach is adopted for the complete and concurrent regeneration of hard tissues-cementum and alveolar bone-and soft tissue-the periodontal ligament (PDL)-at a periodontal defect site. The porous tri-layered nanocomposite hydrogel scaffold is composed of chitin-poly(lactic-co-glycolic acid) (PLGA)/nanobioactive glass ceramic (nBGC)/cementum protein 1 as the cementum layer, chitin-PLGA/fibroblast growth factor 2 as the PDL layer, and chitin-PLGA/nBGC/platelet-rich plasma derived growth factors as the alveolar bone layer. The tri-layered nanocomposite hydrogel scaffold is cytocompatible and favored cementogenic, fibrogenic, and osteogenic differentiation of human dental follicle stem cells. In vivo, tri-layered nanocomposite hydrogel scaffold with/without growth factors is implanted into rabbit maxillary periodontal defects and compared with the controls at 1 and 3 months postoperatively. The tri-layered nanocomposite hydrogel scaffold with growth factors demonstrates complete defect closure and healing with new cancellous-like tissue formation on microcomputed tomography analysis. Histological and immunohistochemical analyses further confirm the formation of new cementum, fibrous PDL, and alveolar bone with well-defined bony trabeculae in comparison to the other three groups. In conclusion, the tri-layered nanocomposite hydrogel scaffold with growth factors can serve as an alternative regenerative approach to achieve simultaneous and complete periodontal regeneration. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Tubular inverse opal scaffolds for biomimetic vessels

    Science.gov (United States)

    Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

    2016-07-01

    There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels.There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially

  3. Scaffold Seeking: A Reverse Design of Scaffolding in Computer-Supported Word Problem Solving

    Science.gov (United States)

    Cheng, Hercy N. H.; Yang, Euphony F. Y.; Liao, Calvin C. Y.; Chang, Ben; Huang, Yana C. Y.; Chan, Tak-Wai

    2015-01-01

    Although well-designed scaffolding may assist students to accomplish learning tasks, its insufficient capability to dynamically assess students' abilities and to adaptively support them may result in the problem of overscaffolding. Our previous project has also shown that students using scaffolds to solve mathematical word problems for a long time…

  4. Biomimetic Scaffold Design for Functional and Integrative Tendon Repair

    Science.gov (United States)

    Zhang, Xinzhi; Bogdanowicz, Danielle; Erisken, Cevat; Lee, Nancy M.; Lu, Helen H.

    2012-01-01

    Rotator cuff tears represent the most common shoulder injuries in the United States. The debilitating effect of this degenerative condition coupled with the high incidence of failure associated with existing graft choices underscore the clinical need for alternative grafting solutions. The two critical design criteria for the ideal tendon graft would require the graft to not only exhibit physiologically relevant mechanical properties but also be able to facilitate functional graft integration by promoting the regeneration of the native tendon-to-bone interface. Centered on these design goals, this review will highlight current approaches to functional and integrative tendon repair. In particular, the application of biomimetic design principles through the use of nanofiber- and nanocomposite-based scaffolds for tendon tissue engineering will be discussed. This review will begin with nanofiber-based approaches to functional tendon repair, followed by a section highlighting the exciting research on tendon-to-bone interface regeneration, with an emphasis on implementation of strategic biomimicry in nanofiber scaffold design and the concomitant formation of graded multi-tissue systems for integrative soft tissue repair. This review will conclude with a summary and future directions section. PMID:22244070

  5. DNA-scaffolded nanoparticle structures

    Energy Technology Data Exchange (ETDEWEB)

    Hoegberg, Bjoern; Olin, Haakan [Department of Engineering Physics and Mathematics, Mid Sweden University, SE-851 70 Sundsvall, Sweden (Sweden)

    2007-03-15

    DNA self-assembly is a powerful route to the production of very small, complex structures. When used in combination with nanoparticles it is likely to become a key technology in the production of nanoelectronics in the future. Previously, demonstrated nanoparticle assemblies have mainly been periodic and highly symmetric arrays, unsuited as building blocks for any complex circuits. With the invention of DNA-scaffolded origami reported earlier this year (Rothemund P W K 2006 Nature 440 (7082) 297-302), a new route to complex nanostructures using DNA has been opened. Here, we give a short review of the field and present the current status of our experiments were DNA origami is used in conjunction with nanoparticles. Gold nanoparticles are functionalized with thiolated single stranded DNA. Strands that are complementary to the gold particle strands can be positioned on the self-assembled DNA-structure in arbitrary patterns. This property should allow an accurate positioning of the particles by letting them hybridize on the lattice. We report on our recent experiments on this system and discuss open problems and future applications.

  6. Regeneration of whole meniscus using meniscal cells and polymer scaffolds in a rabbit total meniscectomy model.

    Science.gov (United States)

    Kang, Sun-Woong; Son, Sun-Mi; Lee, Jae-Sun; Lee, Eung-Seok; Lee, Kwon-Yong; Park, Sang-Guk; Park, Jung-Ho; Kim, Byung-Soo

    2006-09-01

    The current treatments of meniscal lesion in knee joint are not perfect to prevent adverse effects of meniscus injury. Tissue engineering of meniscus using meniscal cells and polymer scaffolds could be an alternative option to treat meniscus injury. This study reports on the regeneration of whole medial meniscus in a rabbit total meniscectomy model using the tissue engineering technique. Biodegradable scaffolds in a meniscal shape were fabricated from polyglycolic acid (PGA) fiber meshes that were mechanically reinforced by bonding PGA fibers at cross points with 75:25 poly(lactic-co-glycolic acid). The compressive modulus of the bonded PGA scaffold was 28-fold higher than that of nonbonded scaffold. Allogeneic meniscal cells were isolated from rabbit meniscus biopsy and cultured in vitro. The expanded meniscal cells were seeded onto the polymer scaffolds, cultured in vitro for 1 week, and transplanted to rabbit knee joints from which medial menisci were removed. Ten or 36 weeks after transplantation, the implants formed neomenisci with the original scaffold shape maintained approximately. Hematoxylin and eosin staining of the sections of the neomenisci at 6 and 10 weeks revealed the regeneration of fibrocartilage. Safranin-O staining showed that abundant proteoglycan was present in the neomenisci at 10 weeks. Masson's trichrome staining indicated the presence of collagen. Immunohistochemical analysis showed that the presence of type I and II collagen in neomenisci at 10 weeks was similar to that of normal meniscal tissue. Biochemical and biomechanical analyses of the tissue-engineered menisci at 36 weeks were performed to determine the quality of the tissue-engineered menisci. Tissue-engineered meniscus showed differences in collagen content and aggregate modulus in comparison with native meniscus. This study demonstrates, for the first time, the feasibility of regenerating whole meniscal cartilage in a rabbit total meniscectomy model using the tissue engineering

  7. Electrospinning PCL Scaffolds Manufacture for Three-Dimensional Breast Cancer Cell Culture

    Directory of Open Access Journals (Sweden)

    Marc Rabionet

    2017-08-01

    Full Text Available In vitro cell culture is traditionally performed within two-dimensional (2D environments, providing a quick and cheap way to study cell properties in a laboratory. However, 2D systems differ from the in vivo environment and may not mimic the physiological cell behavior realistically. For instance, 2D culture models are thought to induce cancer stem cells (CSCs differentiation, a rare cancer cell subpopulation responsible for tumor initiation and relapse. This fact hinders the development of therapeutic strategies for tumors with a high relapse percentage, such as triple negative breast cancer (TNBC. Thus, three-dimensional (3D scaffolds have emerged as an attractive alternative to monolayer culture, simulating the extracellular matrix structure and maintaining the differentiation state of cells. In this work, scaffolds were fabricated through electrospinning different poly(ε-caprolactone-acetone solutions. Poly(ε-caprolactone (PCL meshes were seeded with triple negative breast cancer (TNBC cells and 15% PCL scaffolds displayed significantly (p < 0.05 higher cell proliferation and elongation than the other culture systems. Moreover, cells cultured on PCL scaffolds exhibited higher mammosphere forming capacity and aldehyde dehydrogenase activity than 2D-cultured cells, indicating a breast CSCs enrichment. These results prove the powerful capability of electrospinning technology in terms of poly(ε-caprolactone nanofibers fabrication. In addition, this study has demonstrated that electrospun 15% PCL scaffolds are suitable tools to culture breast cancer cells in a more physiological way and to expand the niche of breast CSCs. In conclusion, three-dimensional cell culture using PCL scaffolds could be useful to study cancer stem cell behavior and may also trigger the development of new specific targets against such malignant subpopulation.

  8. Differentiation of Dental Pulp Stem Cells on Gutta-Percha Scaffolds

    OpenAIRE

    Liudi Zhang; Yingjie Yu; Christopher Joubert; George Bruder; Ying Liu; Chung-Chueh Chang; Marcia Simon; Walker, Stephen G.; Miriam Rafailovich

    2016-01-01

    Advances in treatment of tooth injury have shown that tooth regeneration from the pulp was a viable alternative of root canal therapy. In this study, we demonstrated that Gutta-percha, nanocomposites primarily used for obturation of the canal, are not cytotoxic and can induce differentiation of dental pulp stem cells (DPSC) in the absence of soluble mediators. Flat scaffolds were obtained by spin coating Si wafers with three Gutta-percha compounds: GuttaCore™, ProTaper™, and Lexicon™. The ima...

  9. A Stem Cell-Seeded Nanofibrous Scaffold for Auditory Nerve Replacement

    Science.gov (United States)

    2015-10-01

    bundle cell-seeded scaffolds in small, defined polymer sheaths. Surgical approaches were generated to facilitate implantation in chemically deafened... manipulate BMP signaling in order to limit high-BMP fates (epidermis) and BMP-inhibited fates (neural plate). Moderate inhibition of BMP signaling...scaffold’s conduit, but the IAM of the guinea pig and limits imposed by the surgical approach make this difficult. Alternatives are being pursued

  10. Scaffolding the "Scaffolding" Metaphor: From Inspiration to a Practical Tool for Kindergarten Teachers

    Science.gov (United States)

    Eshach, Haim; Dor-Ziderman, Yair; Arbel, Yael

    2011-10-01

    The present research aims shifting `scaffolding' from an inspiring metaphor to a practical tool to be used by kindergarten teachers when conducting scientific activities. It identifies scaffolding strategies that three experienced kindergarten teachers, ones acknowledged as excelling in science teaching, implicitly used when conducting science activities. For this end 20 whole-day observations were recorded in each of the three kindergartens and transcribed verbatim. The scaffolding strategies were identified through an inductive analysis performed on the observations and through the relevant literature. The strategies yielded from the analysis were grouped into affective and cognitive domains, each divided into categories and subcategories. The complete set of identified strategies was termed the scaffolding scheme. The scaffolding scheme can assist kindergarten and primary school teachers, as well as researchers, in analyzing scientific activities conducted in the kindergarten and judging how efficient the employed strategies are, what strategies to eliminate, and what other strategies might be needed.

  11. Modifying bone scaffold architecture in vivo with permanent magnets to facilitate fixation of magnetic scaffolds.

    Science.gov (United States)

    Panseri, S; Russo, A; Sartori, M; Giavaresi, G; Sandri, M; Fini, M; Maltarello, M C; Shelyakova, T; Ortolani, A; Visani, A; Dediu, V; Tampieri, A; Marcacci, M

    2013-10-01

    The fundamental elements of tissue regeneration are cells, biochemical signals and the three-dimensional microenvironment. In the described approach, biomineralized-collagen biomaterial functions as a scaffold and provides biochemical stimuli for tissue regeneration. In addition superparamagnetic nanoparticles were used to magnetize the biomaterials with direct nucleation on collagen fibres or impregnation techniques. Minimally invasive surgery was performed on 12 rabbits to implant cylindrical NdFeB magnets in close proximity to magnetic scaffolds within the lateral condyles of the distal femoral epiphyses. Under this static magnetic field we demonstrated, for the first time in vivo, that the ability to modify the scaffold architecture could influence tissue regeneration obtaining a well-ordered tissue. Moreover, the association between NdFeB magnet and magnetic scaffolds represents a potential technique to ensure scaffold fixation avoiding micromotion at the tissue/biomaterial interface.

  12. The antler-like appendages of the primitive deer Dicrocerus elegans: morphology, growth cycle, ontogeny, and sexual dimorphism

    Directory of Open Access Journals (Sweden)

    Andrés, M.

    2011-12-01

    Full Text Available Males and many females of the primitive deer Dicrocerus elegans from Sansan (Middle Miocene, France bore antler-like appendages consisting of a simple-branched protoantler growing from a rather long pedicle and are decorated with ridges and furrows. The protoantler capacity to be rejected and subsequently re-grow is clearly evidenced by the presence of both pedicle and protoantler cast specimens. The youngest appendage is a long, laterally flattened shaft whose apex is usually forked with no appreciable limit between the pedicle and the protoantler. In females, the anterior and posterior appendage margins form a more acute angle than that of males, and are more parallel when viewed laterally. After the first casting, the protoantler base is larger than the pedicle top and a coronet-like structure appears developed only around the medial side. With successive castings, the pedicles become shorter and their section is more circular, while protoantlers become much bigger, and have much longer and more separated branches. Branches of females are shorter than those of males, especially the anterior one, and appear in a straight line, instead of being bent. In oldest appendages, the branches are shorter and more similar in size. Accessory branches and irregularities of this basic morphology are common. The separation between both sex morphotypes appears clearly evidenced by Discriminant and Principal Component Analyses. Histological features point to important differences with true antlers and suggest that casting could not occur annually. A core of spongy bone trabeculae is not developed. Once growth is completed, the mineralization progress from the core to the periphery and when the final ‘velvet’ protoantler becomes completely petrified, the tissues dies and the velvet-like skin is cleaned. A high degree of both wear and polish of the branch apices evidence the hard, bare, dead protoantler phase before casting. Due to the complete growth cycle

  13. Biodegradable Polymer-Based Scaffolds for Bone Tissue Engineering

    CERN Document Server

    Sultana, Naznin

    2013-01-01

    This book addresses the principles, methods and applications of biodegradable polymer based scaffolds for bone tissue engineering. The general principle of bone tissue engineering is reviewed and the traditional and novel scaffolding materials, their properties and scaffold fabrication techniques are explored. By acting as temporary synthetic extracellular matrices for cell accommodation, proliferation, and differentiation, scaffolds play a pivotal role in tissue engineering. This book does not only provide the comprehensive summary of the current trends in scaffolding design but also presents the new trends and directions for scaffold development for the ever expanding tissue engineering applications.

  14. Maltodextrin enhances biofilm elimination by electrochemical scaffold.

    Science.gov (United States)

    Sultana, Sujala T; Call, Douglas R; Beyenal, Haluk

    2016-10-26

    Electrochemical scaffolds (e-scaffolds) continuously generate low concentrations of H2O2 suitable for damaging wound biofilms without damaging host tissue. Nevertheless, retarded diffusion combined with H2O2 degradation can limit the efficacy of this potentially important clinical tool. H2O2 diffusion into biofilms and bacterial cells can be increased by damaging the biofilm structure or by activating membrane transportation channels by exposure to hyperosmotic agents. We hypothesized that e-scaffolds would be more effective against Acinetobacter baumannii and Staphylococcus aureus biofilms in the presence of a hyperosmotic agent. E-scaffolds polarized at -600 mVAg/AgCl were overlaid onto preformed biofilms in media containing various maltodextrin concentrations. E-scaffold alone decreased A. baumannii and S. aureus biofilm cell densities by (3.92 ± 0.15) log and (2.31 ± 0.12) log, respectively. Compared to untreated biofilms, the efficacy of the e-scaffold increased to a maximum (8.27 ± 0.05) log reduction in A. baumannii and (4.71 ± 0.12) log reduction in S. aureus biofilm cell densities upon 10 mM and 30 mM maltodextrin addition, respectively. Overall ~55% decrease in relative biofilm surface coverage was achieved for both species. We conclude that combined treatment with electrochemically generated H2O2 from an e-scaffold and maltodextrin is more effective in decreasing viable biofilm cell density.

  15. Engineering functionally graded tissue engineering scaffolds.

    Science.gov (United States)

    Leong, K F; Chua, C K; Sudarmadji, N; Yeong, W Y

    2008-04-01

    Tissue Engineering (TE) aims to create biological substitutes to repair or replace failing organs or tissues due to trauma or ageing. One of the more promising approaches in TE is to grow cells on biodegradable scaffolds, which act as temporary supports for the cells to attach, proliferate and differentiate; after which the scaffold will degrade, leaving behind a healthy regenerated tissue. Tissues in nature, including human tissues, exhibit gradients across a spatial volume, in which each identifiable layer has specific functions to perform so that the whole tissue/organ can behave normally. Such a gradient is termed a functional gradient. A good TE scaffold should mimic such a gradient, which fulfils the biological and mechanical requirements of the target tissue. Thus, the design and fabrication process of such scaffolds become more complex and the introduction of computer-aided tools will lend themselves well to ease these challenges. This paper reviews the needs and characterization of these functional gradients and the computer-aided systems used to ease the complexity of the scaffold design stage. These include the fabrication techniques capable of building functionally graded scaffolds (FGS) using both conventional and rapid prototyping (RP) techniques. They are able to fabricate both continuous and discrete types of FGS. The challenge in fabricating continuous FGS using RP techniques lies in the development of suitable computer aided systems to facilitate continuous FGS design. What have been missing are the appropriate models that relate the scaffold gradient, e.g. pore size, porosity or material gradient, to the biological and mechanical requirements for the regeneration of the target tissue. The establishment of these relationships will provide the foundation to develop better computer-aided systems to help design a suitable customized FGS.

  16. Stratified scaffold design for engineering composite tissues.

    Science.gov (United States)

    Mosher, Christopher Z; Spalazzi, Jeffrey P; Lu, Helen H

    2015-08-01

    A significant challenge to orthopaedic soft tissue repair is the biological fixation of autologous or allogeneic grafts with bone, whereby the lack of functional integration between such grafts and host bone has limited the clinical success of anterior cruciate ligament (ACL) and other common soft tissue-based reconstructive grafts. The inability of current surgical reconstruction to restore the native fibrocartilaginous insertion between the ACL and the femur or tibia, which minimizes stress concentration and facilitates load transfer between the soft and hard tissues, compromises the long-term clinical functionality of these grafts. To enable integration, a stratified scaffold design that mimics the multiple tissue regions of the ACL interface (ligament-fibrocartilage-bone) represents a promising strategy for composite tissue formation. Moreover, distinct cellular organization and phase-specific matrix heterogeneity achieved through co- or tri-culture within the scaffold system can promote biomimetic multi-tissue regeneration. Here, we describe the methods for fabricating a tri-phasic scaffold intended for ligament-bone integration, as well as the tri-culture of fibroblasts, chondrocytes, and osteoblasts on the stratified scaffold for the formation of structurally contiguous and compositionally distinct regions of ligament, fibrocartilage and bone. The primary advantage of the tri-phasic scaffold is the recapitulation of the multi-tissue organization across the native interface through the layered design. Moreover, in addition to ease of fabrication, each scaffold phase is similar in polymer composition and therefore can be joined together by sintering, enabling the seamless integration of each region and avoiding delamination between scaffold layers.

  17. Maltodextrin enhances biofilm elimination by electrochemical scaffold

    Science.gov (United States)

    Sultana, Sujala T.; Call, Douglas R.; Beyenal, Haluk

    2016-01-01

    Electrochemical scaffolds (e-scaffolds) continuously generate low concentrations of H2O2 suitable for damaging wound biofilms without damaging host tissue. Nevertheless, retarded diffusion combined with H2O2 degradation can limit the efficacy of this potentially important clinical tool. H2O2 diffusion into biofilms and bacterial cells can be increased by damaging the biofilm structure or by activating membrane transportation channels by exposure to hyperosmotic agents. We hypothesized that e-scaffolds would be more effective against Acinetobacter baumannii and Staphylococcus aureus biofilms in the presence of a hyperosmotic agent. E-scaffolds polarized at −600 mVAg/AgCl were overlaid onto preformed biofilms in media containing various maltodextrin concentrations. E-scaffold alone decreased A. baumannii and S. aureus biofilm cell densities by (3.92 ± 0.15) log and (2.31 ± 0.12) log, respectively. Compared to untreated biofilms, the efficacy of the e-scaffold increased to a maximum (8.27 ± 0.05) log reduction in A. baumannii and (4.71 ± 0.12) log reduction in S. aureus biofilm cell densities upon 10 mM and 30 mM maltodextrin addition, respectively. Overall ~55% decrease in relative biofilm surface coverage was achieved for both species. We conclude that combined treatment with electrochemically generated H2O2 from an e-scaffold and maltodextrin is more effective in decreasing viable biofilm cell density. PMID:27782161

  18. Fibrosis and electrophysiological characteristics of the atrial appendage in patients with atrial fibrillation and structural heart disease.

    Science.gov (United States)

    van Brakel, Thomas J; van der Krieken, Thomas; Westra, Sjoerd W; van der Laak, Jeroen A; Smeets, Joep L; van Swieten, Henry A

    2013-11-01

    This study was conducted to investigate the degree of fibrosis in atrial appendages of patients with and without atrial fibrillation (AF) undergoing cardiac surgery. In addition, we hypothesized that areas of atrial fibrosis can be identified by electrogram fractionation and low voltage for potential ablation therapy. Interstitial fibrosis from right (RAA) and/or left atrial appendages (LAA) was studied in patients with sinus rhythm (SR, n = 8), paroxysmal (n = 21), and persistent AF (n = 20) undergoing coronary artery bypass and/or aortic or mitral valve surgery. Atrial fibrosis quantification was performed with Masson trichrome staining. Intraoperative bipolar epicardial electrophysiological measurements were performed to correlate fibrosis to electrogram fractionation, voltage, and AF cycle length. The average degree of fibrosis was 11.2 ± 7.2 % in the LAA and 22.8 ± 7.6 % in the RAA (p Fibrosis was not significantly higher in paroxysmal AF patients compared to SR subjects (18.2 ± 8.7 versus 20.7 ± 5.3 %). Persistent AF patients had a higher degree of LAA and RAA fibrosis compared to paroxysmal AF patients (LAA 14.6 ± 8.7 versus 8.6 ± 4.7 %, p = 0.02, and RAA 28.2 ± 7.9 versus 18.2 ± 8.7 %, respectively, p = 0.04). The left atrial end diastolic volume index was higher in persistent AF patients compared to SR controls (38.3 ± 16.4 and 28 ± 11 ml/m(2), respectively, p = 0.04). No correlation between atrial fibrosis and electrogram fractionation or voltage was found. Patients with structural heart disease undergoing cardiac surgery have more fibrosis in the RAA than in the LAA. Furthermore, RAA fibrosis is increased in persistent AF but not paroxysmal AF patients compared to control subjects. Electrogram fractionation and low voltage did not provide accurate identification of the fibrotic substrate.

  19. 原发性肠脂垂炎的MSCT诊断价值%MSCT Diagnosis of Primary Epiploic Appendagitis

    Institute of Scientific and Technical Information of China (English)

    程少容; 余小夫; 阳昱恒; 陈信坚

    2011-01-01

    目的 探讨多层螺旋CT(MSCT)多平面重组(multiple planar reconstruction,MPR)诊断原发性肠脂垂炎(primary epiploic appendagitis,PEA)的价值.资料与方法 搜集PEA患者资料5例,行下腹部及盆腔CT扫描,均行剖腹探查手术,术后病理证实为PEA.结果 5例PEA均发生于结肠旁沟,其中位于盲肠周围1例,升结肠周围1例,乙状结肠周围3例.CT特征表现为结肠旁沟内圆形或椭圆形含脂肪密度肿块,增强后呈环形强化,且邻近肠壁无增厚及肠管周围无积液等征象.结论 MSCT MPR能够准确地显示结肠及结肠旁沟的解剖结构,并且能发现病变,确定病变的部位、大小、范围及与周围组织的关系,对PEA诊断具有决定意义.%Objective To explore the diagnostic value of multi-slice computed tomography (MSCT) in the primary epip-loic appendagitis (PEA). Materials and Methods A retrospective analysis of 5 patients with PEA proved by surgical operation was performed and 5 patients were evaluated with pelvic and lower abdominal MSCT. The CT findings of PEA including location, echogenicity, size, margin and vascularity were observed. Results All cases with PEA occurred around the colons. Among these cases,leases were found around cecum,l case around ascending colon,3 around sigmoid colon respectively. The CT features of PEA were characteristic, which were a round or oval pericolonic fatty lesion with a hyperden-sity rim (ring sign) and adjacent fat stranding with an absence of other causes of inflammation. Conclusion PEA has characteristic MSCT appearances,MSCT MPR is of great value in the diagnosis of PEA.

  20. Exoskeleton Morphology of Three Species of Preponini, with Discussion of Morphological Similarities among Neotropical Charaxinae (Lepidoptera: Nymphalidae)-II. Thorax and Thoracic Appendages.

    Science.gov (United States)

    Bonfantti, Dayana; Casagrande, Mirna Martins; Mielke, Olaf Hermann Hendrik

    2015-06-01

    The present report, the second part of a study of the external morphology of Preponini, compares the thorax and thoracic appendages of Archaeoprepona demophon demophon (Linnaeus, 1758), Archaeoprepona licomedes licomedes (Cramer, 1777) and Prepona pylene pylene Hewitson, [1854], through descriptions and illustrations. The results are compared with three other species, Prepona claudina annetta (Gray, 1832), Memphis moruus stheno Hübner, [1819] and Zaretis itys itylus (Westwood, 1850), revealing previously unrecognized similarities among species of Charaxinae.

  1. Atrial Fibrillation associated chromosome 4q25 variants are not associated with PITX2c expression in human adult left atrial appendages.

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    Shamone R Gore-Panter

    Full Text Available Atrial Fibrillation (AF, the most common sustained arrhythmia, has a strong genetic component, but the mechanism by which common genetic variants lead to increased AF susceptibility is unknown. Genome-wide association studies (GWAS have identified that the single nucleotide polymorphisms (SNPs most strongly associated with AF are located on chromosome 4q25 in an intergenic region distal to the PITX2 gene. Our objective was to determine whether the AF-associated SNPs on chromosome 4q25 were associated with PITX2c expression in adult human left atrial appendages. Analysis of a lone AF GWAS identified four independent AF risk SNPs at chromosome 4q25. Human adult left atrial appendage tissue was obtained from 239 subjects of European Ancestry and used for SNP analysis of genomic DNA and determination of PITX2c RNA expression levels by quantitative PCR. Subjects were divided into three groups based on their history of AF and pre-operative rhythm. AF rhythm subjects had higher PITX2c expression than those with history of AF but in sinus rhythm. PITX2c expression was not associated with the AF risk SNPs in human adult left atrial appendages in all subjects combined or in each of the three subgroups. However, we identified seven SNPs modestly associated with PITX2c expression located in the introns of the ENPEP gene, ∼54 kb proximal to PITX2. PITX2c expression in human adult left atrial appendages is not associated with the chromosome 4q25 AF risk SNPs; thus, the mechanism by which these SNPs are associated with AF remains enigmatic.

  2. Constructive tissue remodeling of biologic scaffolds: A phenomenon associated with scaffold characteristics and distinctive macrophage phenotypes

    Science.gov (United States)

    Brown, Bryan Nicklaus

    Scaffolds composed of extracellular matrix (ECM) have been shown to promote formation of site-specific, functional host tissue following implantation in a number of preclinical and clinical settings. However, the exact mechanisms by which ECM scaffolds are able to promote this type of "constructive tissue remodeling" are unknown. Further, the ability of ECM scaffolds to promote constructive tissue remodeling appears to be dependent on the methods used in their production and the applications in which they are utilized. Therefore, a comprehensive understanding of ECM scaffold characteristics and their effects upon the host response and subsequent tissue remodeling outcome is essential to the design of intelligent scaffolds for specific clinical applications. The present work investigated the effects of tissue source and chemical cross-linking upon the resulting ECM scaffolds, showing that ECM scaffold materials have distinct ultrastructural and compositional characteristics which are dependant on the anatomic location from which the scaffolds are derived and the methods used in their production. These characteristics were associated with distinct patterns of cell behavior in vitro. Distinct tissue remodeling outcomes were observed following implantation of a subset of these scaffold materials in a rat abdominal wall musculature reconstruction model. Acellular, non-cross-linked ECM was associated with constructive tissue remodeling while scaffolds that contained cellular components or were chemically cross-linked resulted in dense connective tissue deposition or encapsulation, respectively. Despite differences in the tissue remodeling outcome, a histologically similar population of macrophages was observed following implantation in each of these cases. Therefore, the phenotype of the macrophage population participating in the host response was investigated. It was shown that scaffolds which resulted in constructive tissue remodeling were associated with an increase

  3. Morphological and molecular data argue for the labrum being non-apical, articulated, and the appendage of the intercalary segment in the locust.

    Science.gov (United States)

    Boyan, G S; Williams, J L D; Posser, S; Bräunig, P

    2002-09-01

    Our analysis of head segmentation in the locust embryo reveals that the labrum is not apical as often interpreted but constitutes the topologically fused appendicular pair of appendages of the third head metamere. Using molecular, immunocytochemical and retrograde axonal staining methods we show that this metamere, the intercalary segment, is innervated by the third brain neuromere-the tritocerebrum. Evidence for the appendicular nature of the labrum is firstly, the presence of an engrailed stripe within its posterior epithelium as is typical of all appendages in the early embryo. Secondly, the labrum is innervated by a segmental nerve originating from the third brain neuromere (the tritocerebrum). Immunocytochemical staining with Lazarillo and horseradish peroxidase antibodies reveal that sensory neurons on the labrum contribute to the segmental (tritocerebral) nerve via the labral nerve in the same way as for the appendages immediately anterior (antenna) and posterior (mandible) on the head. All but one of the adult and embryonic motoneurons innervating the muscles of the labrum have their cell bodies and dendrites located completely within the tritocerebral neuromere and putatively derive from engrailed expressing tritocerebral neuroblasts. Molecular evidence (repo) suggests the labrum is not only appendicular but also articulated, comprising two jointed elements homologous to the coxa and trochanter of the leg.

  4. Scaffolds in regenerative endodontics: A review

    Directory of Open Access Journals (Sweden)

    Kinjal M Gathani

    2016-01-01

    Full Text Available Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. ′A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria ′Platelet rich plasma′, ′Platelet rich fibrin′, ′Stem cells′, ′Natural and artificial scaffolds′ from 1982-2015′. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon.

  5. Scaffolds in regenerative endodontics: A review

    Science.gov (United States)

    Gathani, Kinjal M.; Raghavendra, Srinidhi Surya

    2016-01-01

    Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. ‘A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria ‘Platelet rich plasma’, ‘Platelet rich fibrin’, ‘Stem cells’, ‘Natural and artificial scaffolds’ from 1982–2015’. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon. PMID:27857762

  6. SCAFFOLD: TISSUE ENGINEERING AND REGENERATIVE MEDICINE

    Directory of Open Access Journals (Sweden)

    Garg Tarun

    2011-12-01

    Full Text Available Scaffolds are the central components, which are used to deliver the cells, drug and gene into the body. Polymeric scaffolds may be prepared as typical 3-D porous matrix, nanofibrous matrix, thermo sensitive sol-gel transition hydrogel or porous microsphere, which provide suitable substrate for cell attachment, cell proliferation, differentiated function, and cell migration. Scaffold matrices have specific advantage over other novel drug delivery systems by achieving high drug loading. This study has been conducted to illustrate the various fabrication techniques of scaffold like Particulate leaching, freeze-drying, Supercritical fluid technology, thermally induced phase separation, Rapid prototyping, powder compaction, sol-gel, melt moulding etc. These techniques allow the preparation of porous structures with regular porosity. The main conclusion of this study is Scaffold provides adequate signals (e.g., through the use of adhesion peptides and growth factors to the cells, to induce and maintain them in their desired differentiation stage and for their survival and growth and their successful utilisation in various fields like bone formation, joint pain inflammation, tumor, periodontal regeneration, In-vivo generation of dental pulp, diabetes, osteochondrogenesis, wound dressing, inhibit bacterial growth, heart disease, repair of nasal and auricular malformation, cartilage development, regulated non-viral gene delivery, as artificial corneas, as heart valve, antiepileptic effect, tendon repair, ligament replacement, plasmid delivery, etc.

  7. Biomimetic collagen scaffolds with anisotropic pore architecture.

    Science.gov (United States)

    Davidenko, N; Gibb, T; Schuster, C; Best, S M; Campbell, J J; Watson, C J; Cameron, R E

    2012-02-01

    Sponge-like matrices with a specific three-dimensional structural design resembling the actual extracellular matrix of a particular tissue show significant potential for the regeneration and repair of a broad range of damaged anisotropic tissues. The manipulation of the structure of collagen scaffolds using a freeze-drying technique was explored in this work as an intrinsically biocompatible way of tailoring the inner architecture of the scaffold. The research focused on the influence of temperature gradients, imposed during the phase of crystallisation of collagen suspensions, upon the degree of anisotropy in the microstructures of the scaffolds produced. Moulding technology was employed to achieve differences in heat transfer rates during the freezing processes. For this purpose various moulds with different configurations were developed with a view to producing uniaxial and multi-directional temperature gradients across the sample during this process. Scanning electron microscopy analysis of different cross-sections (longitudinal and horizontal) of scaffolds revealed that highly aligned matrices with axially directed pore architectures were obtained where single unidirectional temperature gradients were induced. Altering the freezing conditions by the introduction of multiple temperature gradients allowed collagen scaffolds to be produced with complex pore orientations, and anisotropy in pore size and alignment.

  8. Macroporous nanowire nanoelectronic scaffolds for synthetic tissues

    Science.gov (United States)

    Tian, Bozhi; Liu, Jia; Dvir, Tal; Jin, Lihua; Tsui, Jonathan H.; Qing, Quan; Suo, Zhigang; Langer, Robert; Kohane, Daniel S.; Lieber, Charles M.

    2012-11-01

    The development of three-dimensional (3D) synthetic biomaterials as structural and bioactive scaffolds is central to fields ranging from cellular biophysics to regenerative medicine. As of yet, these scaffolds cannot electrically probe the physicochemical and biological microenvironments throughout their 3D and macroporous interior, although this capability could have a marked impact in both electronics and biomaterials. Here, we address this challenge using macroporous, flexible and free-standing nanowire nanoelectronic scaffolds (nanoES), and their hybrids with synthetic or natural biomaterials. 3D macroporous nanoES mimic the structure of natural tissue scaffolds, and they were formed by self-organization of coplanar reticular networks with built-in strain and by manipulation of 2D mesh matrices. NanoES exhibited robust electronic properties and have been used alone or combined with other biomaterials as biocompatible extracellular scaffolds for 3D culture of neurons, cardiomyocytes and smooth muscle cells. Furthermore, we show the integrated sensory capability of the nanoES by real-time monitoring of the local electrical activity within 3D nanoES/cardiomyocyte constructs, the response of 3D-nanoES-based neural and cardiac tissue models to drugs, and distinct pH changes inside and outside tubular vascular smooth muscle constructs.

  9. Heterogeneity of Scaffold Biomaterials in Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Lauren Edgar

    2016-05-01

    Full Text Available Tissue engineering (TE offers a potential solution for the shortage of transplantable organs and the need for novel methods of tissue repair. Methods of TE have advanced significantly in recent years, but there are challenges to using engineered tissues and organs including but not limited to: biocompatibility, immunogenicity, biodegradation, and toxicity. Analysis of biomaterials used as scaffolds may, however, elucidate how TE can be enhanced. Ideally, biomaterials should closely mimic the characteristics of desired organ, their function and their in vivo environments. A review of biomaterials used in TE highlighted natural polymers, synthetic polymers, and decellularized organs as sources of scaffolding. Studies of discarded organs supported that decellularization offers a remedy to reducing waste of donor organs, but does not yet provide an effective solution to organ demand because it has shown varied success in vivo depending on organ complexity and physiological requirements. Review of polymer-based scaffolds revealed that a composite scaffold formed by copolymerization is more effective than single polymer scaffolds because it allows copolymers to offset disadvantages a single polymer may possess. Selection of biomaterials for use in TE is essential for transplant success. There is not, however, a singular biomaterial that is universally optimal.

  10. Far field R-wave sensing in Myotonic Dystrophy type 1: right atrial appendage versus Bachmann's bundle region lead placement.

    Science.gov (United States)

    Russo, Vincenzo; Nigro, Gerardo; Antonio Papa, Andrea; Rago, Anna; Di Meo, Federica; Cristiano, Anna; Molino, Antonio; Calabrò, Raffaele; Giovanna Russo, Maria; Politano, Luisa

    2014-10-01

    Aim of the present study was to investigate far field R-wave sensing (FFRS) timing and characteristics in 34 Myotonic Dystrophy type 1 (DM1) patients undergoing dual chamber pacemaker implantation, comparing Bachmann's bundle (BB) stimulation (16 patients) site with the conventional right atrial appendage (RAA) pacing site (18 patients). All measurements were done during sinus rhythm and in supine position, with unipolar (UP) and bipolar (BP) sensing configuration. The presence, amplitude threshold (FFRS trsh) and FFRS timing were determined. There were no differences between both atrial sites in the Pmin and Pmean values of sensed P-wave amplitudes, as well as between UP and BP sensing configurations. The FFRS trsh was lower at the BB region in comparison to the RAA site. The mean BP FFRS trsh was significantly lower than UP configuration in both atrial locations. There were no significant differences in atrial pacing threshold, sensing threshold and atrial lead impedances at the implant time and at FFRS measurements. Bachmann's bundle area is an optimal atrial lead position for signal sensing as well as conventional RAA, but it offers the advantage of reducing the oversensing of R-wave on the atrial lead, thus improving functioning of standard dual chamber pacemakers in DM1 patients.

  11. Quantitative Evaluation of the Substantially Variable Morphology and Function of the Left Atrial Appendage and Its Relation with Adjacent Structures.

    Science.gov (United States)

    Li, Cai-Ying; Gao, Bu-Lang; Liu, Xiao-Wei; Fan, Qiong-Ying; Zhang, Xue-Jing; Liu, Guo-Chao; Yang, Hai-Qing; Feng, Ping-Yong; Wang, Yong; Song, Peng

    2015-01-01

    To investigate quantitatively the morphology, anatomy and function of the left atrial appendage (LAA) and its relation with adjacent structures. A total of 860 patients (533 men, 62.0%, age 55.9±10.4 year) who had cardiac multidetector computed tomography angiography from May to October 2012 were enrolled for analysis. Seven types and 6 subtypes of LAA morphology were found with Type 2 being the most prevalent. Type 5 was more significantly (Pwater drop-like in 3.2%, round in 2.4% and foot-like in 1.6%. The LAA orifice had a significantly greater (Pvolume, aortic cross area long axis or LSPV long axis but poor correlation with the height, weight, surface area and vertebral body height of the patients. Four types of LAA ridge were identified: AI, AII, B and C with the distribution of 17.6%, 69.9%, 5.9% and 6.6%, respectively. The LAA had a significantly (Pvolume at 45% phase but the least volume at 5% phase. The LAA maximal, minimal and emptying volumes were all significantly (Pvolume but no correlation with the maximal volume. The LAA has substantially variable morphologies and relation with the adjacent structures, which may be helpful in guiding the LAA trans-catheter occlusion or catheter ablation procedures.

  12. Pulmonary artery perforation and coronary air embolism-two fatal outcomes in percutaneous left atrial appendage occlusion.

    Science.gov (United States)

    Zwirner, J; Bayer, R; Hädrich, C; Bollmann, A; Klein, N; Dreßler, J; Ondruschka, B

    2017-01-01

    Percutaneous left atrial appendage (LAA) closure is a routinely performed method to reduce the risk of stroke in patients suffering from atrial fibrillation, when an oral anticoagulation is no longer indicated due to relevant bleeding complications. Currently, the Amplatzer Amulet and the Watchman system are two equally used systems. While there is an acute success rate of more than 95 per cent for this intervention, several minor and major complications such as pericardial effusions, air embolism, vascular lesions in proximity to the heart or even death can occur. Here, we report two cases of very rare fatal outcomes in percutaneous LAA occlusion. Eight hours after deployment of an Amplatzer Amulet a patient died, after the pulmonary trunk was perforated by a hook of the occluder device causing pericardial tamponade. In the second case during final radiological position control of the deployed Watchman occluder air was injected accidentally. The patient immediately died due to coronary air embolism. Forensic autopsies are necessary to solve the cause and manner of death, to evaluate and develop medical devices and to rule out medical malpractice. Thus, a close collaboration of legal medicine and the various cardiologic departments is proposed.

  13. The function of Hox and appendage-patterning genes in the development of an evolutionary novelty, the Photuris firefly lantern.

    Science.gov (United States)

    Stansbury, Matthew S; Moczek, Armin P

    2014-05-01

    Uncovering the mechanisms underlying the evolution of novel traits is a central challenge in biology. The lanterns of fireflies are complex traits that lack even remote homology to structures outside luminescent beetle families. Representing unambiguous novelties by the strictest definition, their developmental underpinnings may provide clues to their origin and offer insights into the mechanisms of innovation in developmental evolution. Lanterns develop within the context of abdominal Hox expression domains, and we hypothesized that lantern formation may be instructed in part by these highly conserved transcription factors. We show that transcript depletion of Abdominal-B in Photuris fireflies results in extensive disruption of the adult lantern, suggesting that the evolution of adult lanterns involved the acquisition of a novel regulatory role for this Hox gene. Using the same approach, we show that the Hox gene abdominal-A may control important secondary aspects of lantern development. Lastly, we hypothesized that lantern evolution may have involved the recruitment of dormant abdominal appendage-patterning domains; however, transcript depletion of two genes, Distal-less and dachshund, suggests that they do not contribute to lantern development. Our results suggest that complex novelties can arise within the confines of ancestral regulatory landscapes through acquisition of novel targets without compromising ancestral functions.

  14. Assessment of normal left atrial appendage anatomy and function over gender and ages by dynamic cardiac CT

    Energy Technology Data Exchange (ETDEWEB)

    Boucebci, Samy; Velasco, Stephane; Duboe, Pier-Olivier; Tasu, Jean-Pierre [University of Poitiers, University Hospital, Department of Radiology, Poitiers (France); Pambrun, Thomas [University of Poitiers, University Hospital, Department of Cardiology, Poitiers (France); Ingrand, Pierre [University of Poitiers, University Institute of Public Health, Poitiers (France)

    2016-05-15

    The aim of this study was to evaluate variations in anatomy and function according to age and gender using cardiac computed tomography (CT) in a large prospective cohort of healthy patients. The left atrial appendage (LAA) is considered the most frequent site of intracardiac thrombus formation. However, variations in normal in vivo anatomy and function according to age and gender remain largely unknown. Three-dimensional (3D) cardiac reconstructions of the LAA were performed from CT scans of 193 consecutive patients. Parameters measured included LAA number of lobes, anatomical position of the LAA tip, angulation measured between the proximal and distal portions, minimum (iVol{sub min}) and maximum (iVol{sub max}) volumes indexed to body surface area (BSA), and ejection fraction (LAAEF). Relationship with age was assessed for each parameter. We found that men had longer and wider LAAs. The iVol{sub min} and iVol{sub max} increased by 0.23 and 0.19 ml per decade, respectively, while LAAEF decreased by 2 % per decade in both sexes. Although LAA volumes increase, LAAEF decreases with age in both sexes. (orig.)

  15. 29 CFR (non - mandatory) Appendix A to Subpart L of Part 1926-Scaffold Specifications

    Science.gov (United States)

    2010-07-01

    ... feet in height, components for heavy-duty horse scaffolds, components made with other materials, and... scaffolds. (f) Horse scaffolds. (g) Form scaffolds and carpenters' bracket scaffolds. (h) Roof bracket... members (except planks) of the scaffold are a minimum of 1,500 lb-f/in2 (stress grade) construction...

  16. Scaffolding in tissue engineering: general approaches and tissue-specific considerations.

    Science.gov (United States)

    Chan, B P; Leong, K W

    2008-12-01

    Scaffolds represent important components for tissue engineering. However, researchers often encounter an enormous variety of choices when selecting scaffolds for tissue engineering. This paper aims to review the functions of scaffolds and the major scaffolding approaches as important guidelines for selecting scaffolds and discuss the tissue-specific considerations for scaffolding, using intervertebral disc as an example.

  17. Novel Scaffolds Fabricated Using Oleuropein for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Hui Fan

    2014-01-01

    Full Text Available We investigated the feasibility of oleuropein as a cross-linking agent for fabricating three-dimensional (3D porous composite scaffolds for bone tissue engineering. Human-like collagen (HLC and nanohydroxyapatite (n-HAp were used to fabricate the composite scaffold by way of cross-linking. The mechanical tests revealed superior properties for the cross-linked scaffolds compared to the uncross-linked scaffolds. The as-obtained composite scaffold had a 3D porous structure with pores ranging from 120 to 300 μm and a porosity of 73.6±2.3%. The cross-linked scaffolds were seeded with MC3T3-E1 Subclone 14 mouse osteoblasts. Fluorescence staining, the Cell Counting Kit-8 (CCK-8 assay, and scanning electron microscopy (SEM indicated that the scaffolds enhanced cell adhesion and proliferation. Our results indicate the potential of these scaffolds for bone tissue engineering.

  18. Effects of Teacher Scaffolding on Students' Oral Reading Fluency ...

    African Journals Online (AJOL)

    This study examined the effects of an English teacher's scaffolding on students' passage reading fluency in Dona Berber Primary School, Ethiopia. ... to examine changes in their reading strategies and fluency as a result of teacher scaffolding.

  19. Scaffolding of small groups’ metacognitive activities with an avatar

    NARCIS (Netherlands)

    Molenaar, I.; Chiu, M.M.; Sleegers, P.; van Boxtel, C.A.M.

    2011-01-01

    Metacognitive scaffolding in a computer-supported learning environment can influence students’ metacognitive activities, metacognitive knowledge and domain knowledge. In this study we analyze how metacognitive activities mediate the relationships between different avatar scaffolds on students’ learn

  20. Scaffolding of small groups' metacognitive activities with an avatar

    NARCIS (Netherlands)

    Molenaar, I.; Chiu, M.M.; Sleegers, P.J.C.; Boxtel, C.A.M. van

    2011-01-01

    Metacognitive scaffolding in a computer-supported learning environment can influence students' metacognitive activities, metacognitive knowledge and domain knowledge. In this study we analyze how metacognitive activities mediate the relationships between different avatar scaffolds on students' learn

  1. Effect of salt leaching on PCL and PLGA(50/50 resorbable scaffolds

    Directory of Open Access Journals (Sweden)

    Samuel Hilsdorf Barbanti

    2008-03-01

    Full Text Available The use of porous bioresorbable scaffolds in the field of tissue engineering represents an alternative for the treatment of lesions and losses of biological tissues. This work evaluates the leaching salt effect of two different processes and polymers. Dense and porous scaffolds were prepared with poly(epson-caprolactone (PCL and poly(D,L-lactic acid-co-glycolic acid (50/50 (PLGA50 by casting and melting compression process. Sodium citrate with particles sizes of 180-250 µm of diameter was used as porogen. The dense and porous samples were immersed in distilled water for 30 hours and evaluated for pH and mass variations, by scanning electronic microscopy (SEM, differential scanning calorimetric (DSC and thermogravimetric analysis (TGA. The results of the analyses showed that the inclusion of the salt and leaching process did not affect the properties of the scaffold, indicating that the method is useful to make porous scaffolds to be potentially used in tissue engineering.

  2. Effect of fetal bovine serum on mineralization in silk fibroin scaffolds.

    Science.gov (United States)

    Vetsch, Jolanda R; Paulsen, Samantha J; Müller, Ralph; Hofmann, Sandra

    2015-02-01

    Fetal bovine serum (FBS) is a common media supplement used in tissue engineering (TE) cultures. The chemical composition of FBS is known to be highly variable between different brands, types or batches and can have a significant impact on cell function. This study investigated the influence of four different FBS types in osteogenic or control medium on mineralization of acellular and cell-seeded silk fibroin (SF) scaffolds. In bone TE, mineralized tissue is considered as the final product of a successful cell culture. Calcium assays and micro-computed tomography scans revealed spontaneous mineralization on SF scaffolds with certain FBS types, even without cells present. In contrast, cell-mediated mineralization was found under osteogenic conditions only. Fourier transform infrared spectroscopy analysis demonstrated a similar ion composition of the mineralization present in scaffolds, whether cell-mediated or spontaneous. These results were confirmed by scanning electron microscopy. This study shows clear evidence for the influence of FBS type on mineralization on SF scaffolds. The suitability of FBS medium supplementation in TE studies is highly questionable with regard to reproducibility of studies and comparability of obtained results. For future TE studies, alternatives to conventional FBS such as defined FBS or serum-free media should be considered, as suggested decades ago.

  3. In vitro chondrogenesis with lysozyme susceptible bacterial cellulose as a scaffold.

    Science.gov (United States)

    Yadav, Vikas; Sun, Lin; Panilaitis, Bruce; Kaplan, David L

    2015-12-01

    A current focus of tissue engineering is the use of adult human mesenchymal stem cells (hMSCs) as an alternative to autologous chondrocytes for cartilage repair. Several natural and synthetic polymers (including cellulose) have been explored as a biomaterial scaffold for cartilage tissue engineering. While bacterial cellulose (BC) has been used in tissue engineering, its lack of degradability in vivo and high crystallinity restricts widespread applications in the field. Recently we reported the formation of a novel bacterial cellulose that is lysozyme-susceptible and -degradable in vivo from metabolically engineered Gluconacetobacter xylinus. Here we report the use of this modified bacterial cellulose (MBC) for cartilage tissue engineering using hMSCs. MBC's glucosaminoglycan-like chemistry, combined with in vivo degradability, suggested opportunities to exploit this novel polymer in cartilage tissue engineering. We have observed that, like BC, MBC scaffolds support cell attachment and proliferation. Chondrogenesis of hMSCs in the MBC scaffolds was demonstrated by real-time RT-PCR analysis for cartilage-specific extracellular matrix (ECM) markers (collagen type II, aggrecan and SOX9) as well as histological and immunohistochemical evaluations of cartilage-specific ECM markers. Further, the attachment, proliferation, and differentiation of hMSCs in MBC showed unique characteristics. For example, after 4 weeks of cultivation, the spatial cell arrangement and collagen type-II and ACAN distribution resembled those in native articular cartilage tissue, suggesting promise for these novel in vivo degradable scaffolds for chondrogenesis.

  4. Chitosan and Its Potential Use as a Scaffold for Tissue Engineering in Regenerative Medicine

    Science.gov (United States)

    Rodríguez-Vázquez, Martin; Vega-Ruiz, Brenda; Ramos-Zúñiga, Rodrigo; Saldaña-Koppel, Daniel Alexander; Quiñones-Olvera, Luis Fernando

    2015-01-01

    Tissue engineering is an important therapeutic strategy to be used in regenerative medicine in the present and in the future. Functional biomaterials research is focused on the development and improvement of scaffolding, which can be used to repair or regenerate an organ or tissue. Scaffolds are one of the crucial factors for tissue engineering. Scaffolds consisting of natural polymers have recently been developed more quickly and have gained more popularity. These include chitosan, a copolymer derived from the alkaline deacetylation of chitin. Expectations for use of these scaffolds are increasing as the knowledge regarding their chemical and biological properties expands, and new biomedical applications are investigated. Due to their different biological properties such as being biocompatible, biodegradable, and bioactive, they have given the pattern for use in tissue engineering for repair and/or regeneration of different tissues including skin, bone, cartilage, nerves, liver, and muscle. In this review, we focus on the intrinsic properties offered by chitosan and its use in tissue engineering, considering it as a promising alternative for regenerative medicine as a bioactive polymer. PMID:26504833

  5. Chitosan and Its Potential Use as a Scaffold for Tissue Engineering in Regenerative Medicine

    Directory of Open Access Journals (Sweden)

    Martin Rodríguez-Vázquez

    2015-01-01

    Full Text Available Tissue engineering is an important therapeutic strategy to be used in regenerative medicine in the present and in the future. Functional biomaterials research is focused on the development and improvement of scaffolding, which can be used to repair or regenerate an organ or tissue. Scaffolds are one of the crucial factors for tissue engineering. Scaffolds consisting of natural polymers have recently been developed more quickly and have gained more popularity. These include chitosan, a copolymer derived from the alkaline deacetylation of chitin. Expectations for use of these scaffolds are increasing as the knowledge regarding their chemical and biological properties expands, and new biomedical applications are investigated. Due to their different biological properties such as being biocompatible, biodegradable, and bioactive, they have given the pattern for use in tissue engineering for repair and/or regeneration of different tissues including skin, bone, cartilage, nerves, liver, and muscle. In this review, we focus on the intrinsic properties offered by chitosan and its use in tissue engineering, considering it as a promising alternative for regenerative medicine as a bioactive polymer.

  6. Nano/macro porous bioactive glass scaffold

    Science.gov (United States)

    Wang, Shaojie

    Bioactive glass (BG) and ceramics have been widely studied and developed as implants to replace hard tissues of the musculo-skeletal system, such as bones and teeth. Recently, instead of using bulk materials, which usually do not degrade rapidly enough and may remain in the human body for a long time, the idea of bioscaffold for tissue regeneration has generated much interest. An ideal bioscaffold is a porous material that would not only provide a three-dimensional structure for the regeneration of natural tissue, but also degrade gradually and, eventually be replaced by the natural tissue completely. Among various material choices the nano-macro dual porous BG appears as the most promising candidate for bioscaffold applications. Here macropores facilitate tissue growth while nanopores control degradation and enhance cell response. The surface area, which controls the degradation of scaffold can also be tuned by changing the nanopore size. However, fabrication of such 3D structure with desirable nano and macro pores has remained challenging. In this dissertation, sol-gel process combined with spinodal decomposition or polymer sponge replication method has been developed to fabricate the nano-macro porous BG scaffolds. Macropores up to 100microm are created by freezing polymer induced spinodal structure through sol-gel transition, while larger macropores (>200um) of predetermined size are obtained by the polymer sponge replication technique. The size of nanopores, which are inherent to the sol-gel method of glass fabrication, has been tailored using several approaches: Before gel point, small nanopores are generated using acid catalyst that leads to weakly-branched polymer-like network. On the other hand, larger nanopores are created with the base-catalyzed gel with highly-branched cluster-like structure. After the gel point, the nanostructure can be further modified by manipulating the sintering temperature and/or the ammonia concentration used in the solvent

  7. Knowledge scaffolding visualizations: A guiding framework

    Directory of Open Access Journals (Sweden)

    Elitsa Alexander

    2015-06-01

    Full Text Available In this paper we provide a guiding framework for understanding and selecting visual representations in the knowledge management (KM practice. We build on an interdisciplinary analogy between two connotations of the notion of “scaffolding”: physical scaffolding from an architectural-engineering perspective and scaffolding of the “everyday knowing in practice” from a KM perspective. We classify visual structures for knowledge communication in teams into four types of scaffolds: grounded (corresponding e.g., to perspectives diagrams or dynamic facilitation diagrams, suspended (e.g., negotiation sketches, argument maps, panel (e.g., roadmaps or timelines and reinforcing (e.g., concept diagrams. The article concludes with a set of recommendations in the form of questions to ask whenever practitioners are choosing visualizations for specific KM needs. Our recommendations aim at providing a framework at a broad-brush level to aid choosing a suitable visualization template depending on the type of KM endeavour.

  8. Scaffolding for Three-Dimensional Embryonic Vasculogenesis

    Science.gov (United States)

    Kraehenbuehl, Thomas P.; Aday, Sezin; Ferreira, Lino S.

    Biomaterial scaffolds have great potential to support efficient vascular differentiation of embryonic stem cells. Vascular cell fate-specific biochemical and biophysical cues have been identified and incorporated into three-dimensional (3D) biomaterials to efficiently direct embryonic vasculogenesis. The resulting vascular-like tissue can be used for regenerative medicine applications, further elucidation of biophysical and biochemical cues governing vasculogenesis, and drug discovery. In this chapter, we give an overview on the following: (1) developmental cues for directed differentiation of human embryonic stem cells (hESCs) into vascular cells, (2) 3D vascular differentiation in embryoid bodies (EBs), (3) preparation of 3D scaffolds for the vascular differentiation of hESCs, and (4) the most significant studies combining scaffolding and hESCs for development of vascular-like tissue.

  9. Jellyfish collagen scaffolds for cartilage tissue engineering.

    Science.gov (United States)

    Hoyer, Birgit; Bernhardt, Anne; Lode, Anja; Heinemann, Sascha; Sewing, Judith; Klinger, Matthias; Notbohm, Holger; Gelinsky, Michael

    2014-02-01

    Porous scaffolds were engineered from refibrillized collagen of the jellyfish Rhopilema esculentum for potential application in cartilage regeneration. The influence of collagen concentration, salinity and temperature on fibril formation was evaluated by turbidity measurements and quantification of fibrillized collagen. The formation of collagen fibrils with a typical banding pattern was confirmed by atomic force microscopy and transmission electron microscopy analysis. Porous scaffolds from jellyfish collagen, refibrillized under optimized conditions, were fabricated by freeze-drying and subsequent chemical cross-linking. Scaffolds possessed an open porosity of 98.2%. The samples were stable under cyclic compression and displayed an elastic behavior. Cytotoxicity tests with human mesenchymal stem cells (hMSCs) did not reveal any cytotoxic effects of the material. Chondrogenic markers SOX9, collagen II and aggrecan were upregulated in direct cultures of hMSCs upon chondrogenic stimulation. The formation of typical extracellular matrix components was further confirmed by quantification of sulfated glycosaminoglycans.

  10. [Scaffold-based Bone Tissue Engineering].

    Science.gov (United States)

    Holzapfel, B M; Rudert, M; Hutmacher, D W

    2017-08-01

    Tissue engineering provides the possibility of regenerating damaged or lost osseous structures without the need for permanent implants. Within this context, biodegradable and bioresorbable scaffolds can provide structural and biomechanical stability until the body's own tissue can take over their function. Additive biomanufacturing makes it possible to design the scaffold's architectural characteristics to specifically guide tissue formation and regeneration. Its nano-, micro-, and macro-architectural properties can be tailored to ensure vascularization, oxygenation, nutrient supply, waste exchange, and eventually ossification not only in its periphery but also in its center, which is not in direct contact with osteogenic elements of the surrounding healthy tissue. In this article we provide an overview about our conceptual design and process of the clinical translation of scaffold-based bone tissue engineering applications.

  11. Postsynaptic scaffolds for nicotinic receptors on neurons

    Institute of Scientific and Technical Information of China (English)

    Robert A NEFF III; David GOMEZ-VARELA; Catarina C FERNANDES; Darwin K BERG

    2009-01-01

    Complex postsynaptic scaffolds determine the structure and signaling capabilities of glutamatergic synapses. Recent studies indicate that some of the same scaffold components contribute to the formation and function of nicotinic synapses on neurons. PDZ-containing proteins comprising the PSD-95 family co-localize with nicotinic acetylcholine receptors (nAChRs) and mediate downstream signaling in the neurons. The PDZ-proteins also promote functional nicotinic innerva- tion of the neurons, as does the scaffold protein APC and transmembrane proteins such as neuroligin and the EphB2 recep- tor. In addition, specific chaperones have been shown to facilitate nAChR assembly and transport to the cell surface. This review summarizes recent results in these areas and raises questions for the future about the mechanism and synaptic role of nAChR trafficking.

  12. Scaffolding Advanced Writing through Writing Frames

    Directory of Open Access Journals (Sweden)

    Sara Salehpour

    2014-05-01

    Full Text Available Mastering writing has always proved an almost insurmountable barrier to EFL learners. In an attempt to alleviate problems advanced EFL learners have with writing, this study aimed at investigating the effect of scaffolded instruction through writing frames constructed from extended prefabricated lexical bundles. 40 female advanced English students, selected out of a population of 65, were randomly assigned into experimental and control groups. The participants of both groups were assigned a writing pre-test prior to any instruction, and a writing post-test following the twenty-session scaffolded instruction in both groups. The results revealed that the participants in the experimental group outperformed their counterparts in the control group as a result of the writing frames they were provided with. Overall, it is concluded that scaffolded instruction through writing frames can be a useful means of helping advanced students to improve their writing quality.

  13. Research Diary: A Tool for Scaffolding

    Directory of Open Access Journals (Sweden)

    Marion Engin Ed.D

    2011-09-01

    Full Text Available Diaries have long been seen as tools for reflection in learning languages, and learning about teaching. Despite this recognition of the importance of narratives in diary writing, little attention has been paid to the role of research diaries in the process of learning about research, and learning how to be a researcher. During the author's own research into the construction of teaching knowledge by pre-service trainees, she became aware that her research diary was scaffolding her own construction of research knowledge. In this article the author discusses the role of a research diary based on a socio-cultural theory of learning. The diary acts as the expert other in the scaffolding of research knowledge by the novice researcher. The discussion of the nature of the scaffolding and the role of diary writing draws on examples from the author's research diary written during her doctoral studies.

  14. SCAFFOLDING IN CONNECTIVIST MOBILE LEARNING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Ozlem OZAN

    2013-04-01

    Full Text Available Social networks and mobile technologies are transforming learning ecology. In this changing learning environment, we find a variety of new learner needs. The aim of this study is to investigate how to provide scaffolding to the learners in connectivist mobile learning environment: Ø to learn in a networked environment, Ø to manage their networked learning process, Ø to interact in a networked society, and Ø to use the tools belonging to the network society. The researcher described how Vygotsky's “scaffolding” concept, Berge’s “learner support” strategies, and Siemens’ “connectivism” approach can be used together to satisfy mobile learners’ needs. A connectivist mobile learning environment was designed for the research, and the research was executed as a mixed-method study. Data collection tools were Facebook wall entries, personal messages, chat records; Twitter, Diigo, blog entries; emails, mobile learning management system statistics, perceived learning survey and demographic information survey. Results showed that there were four major aspects of scaffolding in connectivist mobile learning environment as type of it, provider of it, and timing of it and strategies of it. Participants preferred mostly social scaffolding, and then preferred respectively, managerial, instructional and technical scaffolding. Social scaffolding was mostly provided by peers, and managerial scaffolding was mostly provided by instructor. Use of mobile devices increased the learner motivation and interest. Some participants stated that learning was more permanent by using mobile technologies. Social networks and mobile technologies made it easier to manage the learning process and expressed a positive impact on perceived learning.

  15. Hemocompatible surface of electrospun nanofibrous scaffolds by ATRP modification

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Wenjie [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Key Laboratory of Systems Bioengineering of Ministry of Education, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Wang, Heyun [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832002 (China); Yang, Dazhi [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); An, Bo [Department of Orthopedics, Affiliated Hospital of Logistics University of Chinese People' s Armed Police Force, Tianjin 300162 (China); Zhang, Wencheng [Department of Physiology and Pathophysiology, Logistics University of Chinese People' s Armed Police Force, Tianjin 300162 (China); Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-10-15

    The electrospun scaffolds are potential application in vascular tissue engineering since they can mimic the nano-sized dimension of natural extracellular matrix (ECM). We prepared a fibrous scaffold from polycarbonateurethane (PCU) by electrospinning technology. In order to improve the hydrophilicity and hemocompatibility of the fibrous scaffold, poly(ethylene glycol) methacrylate (PEGMA) was grafted onto the fiber surface by surface-initiated atom transfer radical polymerization (SI-ATRP) method. Although SI-ATRP has been developed and used for surface modification for many years, there are only few studies about the modification of electrospun fiber by this method. The modified fibrous scaffolds were characterized by SEM, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The scaffold morphology showed no significant difference when PEGMA was grafted onto the scaffold surface. Based on the water contact angle measurement, the surface hydrophilicity of the scaffold surface was improved significantly after grafting hydrophilic PEGMA (P = 0.0012). The modified surface showed effective resistance for platelet adhesion compared with the unmodified surface. Activated partial thromboplastin time (APTT) of the PCU-g-PEGMA scaffold was much longer than that of the unmodified PCU scaffold. The cyto-compatibility of electrospun nanofibrous scaffolds was tested by human umbilical vein endothelial cells (HUVECs). The images of 7-day cultured cells on the scaffold surface were observed by SEM. The modified scaffolds showed high tendency to induce cell adhesion. Moreover, the cells reached out pseudopodia along the fibrous direction and formed a continuous monolayer. Hemolysis test showed that the grafted chains of PEGMA reduced blood coagulation. These results indicated that the modified electrospun nanofibrous scaffolds were potential application as artificial blood vessels. Highlights: • Electrospun nanofibrous scaffolds were successfully

  16. Producing ORMOSIL scaffolds by femtosecond laser polymerization

    Science.gov (United States)

    Matei, A.; Zamfirescu, M.; Radu, C.; Buruiana, E. C.; Buruiana, T.; Mustaciosu, C.; Petcu, I.; Radu, M.; Dinescu, M.

    2012-07-01

    Structures with different geometries and sizes were built via direct femtosecond laser writing, starting from new organic/inorganic hybrid monomers based on hybrid methacrylate containing triethoxysilane, in addition to urethane and urea groups. Multifunctional oligomer of urethane dimethacrylate type was chosen as comonomer in polymerization experiments because dimethacrylates give rise to the formation of a polymer network, having a number of favorable properties including biocompatibility and surface nanostructuring. Free standing polymeric structures were designed and created in order to be tested in fibroblast cells culture. Investigations of the cellular adhesion, proliferation, and viability of L929 mouse fibroblasts on free-standing laser processed scaffolds were performed for different scaffold designs.

  17. 29 CFR 1910.28 - Safety requirements for scaffolding.

    Science.gov (United States)

    2010-07-01

    ... intended. (8) All load-carrying timber members of scaffold framing shall be a minimum of 1,500 f. (Stress... displacement. (7) Scaffolds shall be level and set upon a firm foundation. (m) Horse scaffolds. (1) Horse... the horses shall be not less than those specified in Table D-19. (3) Horses shall be spaced not...

  18. Development of Composite Scaffolds for Load Bearing Segmental Bone Defects

    Science.gov (United States)

    2013-07-01

    composite scaffolds designed to serve as bone regenerative therapies . We analyzed the benefits and drawbacks of different composite scaffold...related to fractures, sport and blast injuries. Diseases include bone cancer (osteosarcoma), tumor resection and reconstruction, osteoporosis ...selection for the scaffold has a direct impact on the biological and physical properties of the construct, there are some factors contributing to the

  19. Scaffolding as a Tool for Environmental Education in Early Childhood

    Science.gov (United States)

    Zurek, Alex; Torquati, Julia; Acar, Ibrahim

    2014-01-01

    This paper describes the process of "scaffolding" as a teaching strategy in early childhood education, and demonstrates how scaffolding can promote children's learning about the natural environment. Examples of scaffolding are provided from seventy-four running record observations made over a two-year period in a nature-based preschool…

  20. Design, fabrication and application of tissue engineering used cells scaffold

    Institute of Scientific and Technical Information of China (English)

    WANG Shenguo; BEI Jianzhong

    2001-01-01

    @@ FUNCTIONS OF CELLS SCAFFOLD IN THE TISSUE ENGINEERINGCell, cells scaffold and the construction of tissue and organ are three main factors for the Tissue Engineering. A main function of cells scaffold in tissue engineering is to provide an environment for cells propagation.

  1. Synthetic, biological and composite scaffolds for abdominal wall reconstruction.

    Science.gov (United States)

    Meintjes, Jennifer; Yan, Sheng; Zhou, Lin; Zheng, Shusen; Zheng, Minghao

    2011-03-01

    The reconstruction of abdominal wall defects remains a huge surgical challenge. Tension-free repair is proven to be superior to suture repair in abdominal wall reconstruction. Scaffolds are essential for tension-free repair. They are used to bridge a defect or reinforce the abdominal wall. A huge variety of scaffolds are now commercially available. Most of the synthetic scaffolds are composed of polypropylene. They provide strong tissue reinforcement, but cause a foreign body reaction, which can result in serious complications. Absorbable synthetic scaffolds, such as Dexon™ (polyglycolic acid) and Vicryl™ (polyglactin 910), are not suitable for abdominal wall reconstruction as they usually require subsequent surgeries to repair recurrent hernias. Composite scaffolds combine the strength of nonabsorbable synthetic scaffolds with the antiadhesive properties of the absorbable scaffold, but require long-term follow-up. Biological scaffolds, such as Permacol™, Surgisis(®) and Alloderm(®), are derived from acellular mammalian tissues. Non-cross-linked biological scaffolds show excellent biocompatibility and degrade slowly over time. However, remnant DNA has been found in several products and the degradation leads to recurrence. Randomized controlled trials with long-term follow-up studies are lacking for all of the available scaffolds, particularly those derived from animal tissue. This article provides an overview of the different types of scaffolds available, and presents the key clinical studies of the commercially available synthetic, composite and biological scaffolds for abdominal wall reconstruction.

  2. Electrospun PVA-PCL-HAB scaffold for craniofacial bone regeneration

    DEFF Research Database (Denmark)

    Prabha, Rahul; Kraft, David Christian Evar; Melsen, Birte

    2015-01-01

    body fluid immersed scaffold samples. Culturing human adult dental pulp stem cells (DPSC) and human bone marrow derived MSC seeded on PVA-PCL-HAB scaffold showed enhanced cell proliferation and in vitro osteoblastic differentiation. Cell-containing scaffolds were implanted subcutaneously in immune...

  3. Alternative Energies

    Energy Technology Data Exchange (ETDEWEB)

    Planting, A.; De saint Jacob, Y.; Verwijs, H.; Belin, H.; Preesman, L.

    2009-03-15

    In two articles, one interview and one column attention is paid to alternative energies. The article 'A new light on saving energy' discusses the option to save energy by modernising lighting systems in urban areas. The column 'View from Paris' focuses on investment decisions in France with regard to renewable energy and energy savings. The article 'Europe turns a blind eye to big battery' discusses developments in batteries to store energy. The interview concerns fuel cell expert and formerly President of UTC Power Jan van Dokkum. The last article gives a brief overview of the European Energy Research Alliance (EERA) and the challenges this alliance will have to face with regard to climate change and energy security.

  4. A comparison of two-dimensional and real-time 3D transoesophageal echocardiography and angiography for assessing the left atrial appendage anatomy for sizing a left atrial appendage occlusion system: impact of volume loading.

    Science.gov (United States)

    Al-Kassou, Baravan; Tzikas, Apostolos; Stock, Friederike; Neikes, Fabian; Völz, Alexander; Omran, Heyder

    2017-04-20

    Correct sizing of a left atrial appendage (LAA) closure system is important to avoid redeployment of the device and peri-device leaks. The aims of this study were to assess the significance of two-dimensional transoesophageal echocardiography (2D-TEE), real-time 3D transoesophageal echocardiography (RT 3D-TEE) and angiography for measuring the size of the LAA landing zone and to determine the impact on sizing an LAA closure device. Furthermore, we investigated the relevance of volume loading on LAA size. In a prospective study, 46 patients underwent 2D-TEE and RT 3D-TEE 24 hours prior to LAA closure, at the beginning of the procedure and just before the procedure after volume loading with an average of 1,035±246 ml. Angiography was performed immediately before the implantation. Maximal diameter (2.2±0.4 versus 2.3±0.4 cm; pcorrelation (R) between measurements and LAA device size was found for RT 3D-TEE-derived perimeter (R=0.97) and area (R=0.96), whereas the maximal diameter (R=0.78) measured by 2D-TEE and angiography (R=0.76) correlated less closely. Sizing based on an RT 3D-TEE-measured perimeter resulted only in 4% of undersizing the implanted device. Peri-device leaks occurred in seven cases (15%) and were associated with a lower compression of LAA devices (7±1.3% versus 14±3.2% for patients without leaks, pcorrelation to LAA closure device size than 2D-TEE or angiographic measurements.

  5. Experimental study on cultivation and purification of bone marrow-derived mesenchymal stem cells and its co-culture with chitosan porous scaffolds in vitro

    Directory of Open Access Journals (Sweden)

    Feng YAN

    2014-12-01

    Full Text Available Background As commonly used scaffold material in tissue engineering, chitosan has many advantages, such as strong biodegradability, low antigenicity, good biocompatibility and no pyrogen reaction. This study aims to isolate, cultivate and purify Sprague-Dawley (SD rat bone marrow-derived mesenchymal stem cells (BMSCs, and to observe the growth of BMSCs when co-cultured with self-made chitosan porous scaffold in vitro and to test the biocompatibility of this tissue engineering scaffold, so as to lay the foundation for promoting nerve regeneration of transplant treatment.  Methods Three-week-old healthy male SD rats were used in this study, and BMSCs were isolated and purified through bone marrow adherent culture method. The surface markers of BMSCs at Passage 3 were detected and identified by flow cytometry (FCM and the BMSCs were three?dimensionally cultured in vitro on chitosan porous scaffolds produced by freeze-drying method. Ethanol alternative method was used to detect the chitosan scaffold porosity. Scanning electron microscope was used to explore the internal structure of the scaffold, measure the size of its aperture, and observe the morphology and development of the cells within the scaffold. Methyl thiazolyl tetrazolium (MTT method was used to determine the cells' proliferation.  Results The cultured BMSCs were uniform and similiar to fibrous arrangement, and mixed cells reduced obviously. The identification result of FCM showed the CD29 positive rate was 98.49% and CD45RA positive rate was only 0.85%. The chitosan scaffold had an interlinked, uniform similar three-dimensional porous structure and its aperture porosity was 90%. Some cells stretched out pseudopod and infiltrated into the porous structure of scaffold, even fusing with them. The BMSCs were seeded in the scaffold successfully. The chitosan scaffold had no obvious effect on BMSCs' proliferation. Conclusions Chitosan porous scaffolds have good structural character and

  6. Indications on suitable scaffold as carrier of stem cells in the alveoloplasty of cleft palate.

    Science.gov (United States)

    Paganelli, C; Fontana, P; Porta, F; Majorana, A; Pazzaglia, U E; Sapelli, P L

    2006-08-01

    Autologous iliac crest bone is used to close the residual alveolar bone defect in cleft palate patients during late mixed dentition. Surgery involves physical and anaesthesiologic risks, long-time hospitalization, high costs and not always good results (15% failure rate). Alternatives to iliac crest bone grafting are going to be evaluated: synthetic, xenograft and allograft matrices combined with platelet-rich plasma or recombined bone morphogenic proteins for osteoinductivity are commercially available. These alternatives have not yet been determined to be equivalent to the previous treatment. A new field of research is represented by stem cells, which have been also used to regenerate ischaemic cardiac tissue after heart attack, to treat hypophosphatasia and osteoporosis. Our aim was to use osteoblasts from stem cells to close the residual palate cleft in association with a suitable carrier. Stem cells are expanded in the Aastrom bioreactor, differentiated into osteoblasts and positioned in the bone defect by means of a Spongostan scaffold. This scaffold has the best characteristics as commercial availability, low cost, good manageability, absence of allergic reactions or other side effects on patient, biocompatibility, imbibition, radiotransparency, reabsorbability and osteoinductivity. Previous studies encourage Spongostan scaffold application.

  7. Enhancing Student Learning through Scaffolded Client Projects

    Science.gov (United States)

    Tomlinson, Elizabeth

    2017-01-01

    This article reports on the current status of client projects (CPs) in business communication courses, provides a scaffolded model for implementing CP, and assesses student learning in CPs. Using a longitudinal mixed method research design, survey data and qualitative materials from six semesters are presented. The instructor survey indicated need…

  8. Comparison of TALEN scaffolds in Xenopus tropicalis

    Directory of Open Access Journals (Sweden)

    Keisuke Nakajima

    2013-11-01

    Transcription activator-like effector nucleases (TALENs are facile and potent tools used to modify a gene of interest for targeted gene knockout. TALENs consist of an N-terminal domain, a DNA-binding domain, and a C-terminal domain, which are derived from a transcription activator-like effector, and the non-specific nuclease domain of FokI. Using Xenopus tropicalis (X. tropicalis, we compared the toxicities and somatic mutation activities of four TALEN architectures in a side-by-side manner: a basic TALEN, a scaffold with the same truncated N- and C-terminal domains as GoldyTALEN, a scaffold with the truncated N- and C-terminal domains and an obligate heterodimeric nuclease domain, and a scaffold with the truncated N- and C-terminal domains and an obligate heterodimeric Sharkey nuclease domain. The strongest phenotype and targeted somatic gene mutation were induced by the injection of TALEN mRNAs containing the truncated N- and C-terminal domains and an obligate heterodimeric nuclease domain. The obligate heterodimeric TALENs exhibited reduced toxicity compared to the homodimeric TALENs, and the homodimeric GoldyTALEN-type scaffold showed both a high activity of somatic gene modification and high toxicity. The Sharkey mutation in the heterodimeric nuclease domain reduced the TALEN-mediated somatic mutagenesis.

  9. Comparison of TALEN scaffolds in Xenopus tropicalis.

    Science.gov (United States)

    Nakajima, Keisuke; Yaoita, Yoshio

    2013-12-15

    Transcription activator-like effector nucleases (TALENs) are facile and potent tools used to modify a gene of interest for targeted gene knockout. TALENs consist of an N-terminal domain, a DNA-binding domain, and a C-terminal domain, which are derived from a transcription activator-like effector, and the non-specific nuclease domain of FokI. Using Xenopus tropicalis (X. tropicalis), we compared the toxicities and somatic mutation activities of four TALEN architectures in a side-by-side manner: a basic TALEN, a scaffold with the same truncated N- and C-terminal domains as GoldyTALEN, a scaffold with the truncated N- and C-terminal domains and an obligate heterodimeric nuclease domain, and a scaffold with the truncated N- and C-terminal domains and an obligate heterodimeric Sharkey nuclease domain. The strongest phenotype and targeted somatic gene mutation were induced by the injection of TALEN mRNAs containing the truncated N- and C-terminal domains and an obligate heterodimeric nuclease domain. The obligate heterodimeric TALENs exhibited reduced toxicity compared to the homodimeric TALENs, and the homodimeric GoldyTALEN-type scaffold showed both a high activity of somatic gene modification and high toxicity. The Sharkey mutation in the heterodimeric nuclease domain reduced the TALEN-mediated somatic mutagenesis.

  10. Joining the Conversation: Scaffolding and Tutoring Mathematics

    Science.gov (United States)

    Valkenburg, Jim

    2010-01-01

    Tutoring is one of those skills which require the ability to communicate an in-depth understanding of the subject. This article is about scaffolding while tutoring, and the tutoring talents described can be applied across the curriculum. Lev Vygotsky's ideas about communication and education play a key role in the development of scaffolding…

  11. Biodegradable elastomeric scaffolds for soft tissue engineering

    NARCIS (Netherlands)

    Pêgo, A.P.; Poot, Andreas A.; Grijpma, Dirk W.; Feijen, Jan

    2003-01-01

    Elastomeric copolymers of 1,3-trimethylene carbonate (TMC) and ε-caprolactone (CL) and copolymers of TMC and D,L-lactide (DLLA) have been evaluated as candidate materials for the preparation of biodegradable scaffolds for soft tissue engineering. TMC-DLLA copolymers are amorphous and degrade more

  12. Engineered biopolymeric scaffolds for chronic wound healing

    Directory of Open Access Journals (Sweden)

    Laura E Dickinson

    2016-08-01

    Full Text Available Skin regeneration requires the coordinated integration of concomitant biological and molecular events in the extracellular wound environment during overlapping phases of inflammation, proliferation, and matrix remodeling. This process is highly efficient during normal wound healing. However, chronic wounds fail to progress through the ordered and reparative wound healing process and are unable to heal, requiring long-term treatment at high costs. There are many advanced skin substitutes, which mostly comprise bioactive dressings containing mammalian derived matrix components and/or human cells, in clinical use. However, it is presently hypothesized that no treatment significantly outperforms the others. To address this unmet challenge, recent research has focused on developing innovative acellular biopolymeric scaffolds as more efficacious wound healing therapies. These biomaterial-based skin substitutes are precisely engineered and fine-tuned to recapitulate aspects of the wound healing milieu and target specific events in the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This mini-review will provide a brief overview of chronic wound healing and current skin substitute treatment strategies while focusing on recent engineering approaches that regenerate skin using synthetic, biopolymeric scaffolds. We discuss key polymeric scaffold design criteria, including degradation, biocompatibility, and microstructure, and how they translate to inductive microenvironments that stimulate cell infiltration and vascularization to enhance chronic wound healing. As healthcare moves towards precision medicine-based strategies, the potential and therapeutic implications of synthetic, biopolymeric scaffolds as tunable treatment modalities for chronic wounds will be considered.

  13. Engineered Biopolymeric Scaffolds for Chronic Wound Healing.

    Science.gov (United States)

    Dickinson, Laura E; Gerecht, Sharon

    2016-01-01

    Skin regeneration requires the coordinated integration of concomitant biological and molecular events in the extracellular wound environment during overlapping phases of inflammation, proliferation, and matrix remodeling. This process is highly efficient during normal wound healing. However, chronic wounds fail to progress through the ordered and reparative wound healing process and are unable to heal, requiring long-term treatment at high costs. There are many advanced skin substitutes, which mostly comprise bioactive dressings containing mammalian derived matrix components, and/or human cells, in clinical use. However, it is presently hypothesized that no treatment significantly outperforms the others. To address this unmet challenge, recent research has focused on developing innovative acellular biopolymeric scaffolds as more efficacious wound healing therapies. These biomaterial-based skin substitutes are precisely engineered and fine-tuned to recapitulate aspects of the wound healing milieu and target specific events in the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This mini-review will provide a brief overview of chronic wound healing and current skin substitute treatment strategies while focusing on recent engineering approaches that regenerate skin using synthetic, biopolymeric scaffolds. We discuss key polymeric scaffold design criteria, including degradation, biocompatibility, and microstructure, and how they translate to inductive microenvironments that stimulate cell infiltration and vascularization to enhance chronic wound healing. As healthcare moves toward precision medicine-based strategies, the potential and therapeutic implications of synthetic, biopolymeric scaffolds as tunable treatment modalities for chronic wounds will be considered.

  14. Bioactive nanofibrous scaffolds for regenerative endodontics.

    Science.gov (United States)

    Bottino, M C; Kamocki, K; Yassen, G H; Platt, J A; Vail, M M; Ehrlich, Y; Spolnik, K J; Gregory, R L

    2013-11-01

    Here we report the synthesis, materials characterization, antimicrobial capacity, and cytocompatibility of novel antibiotic-containing scaffolds. Metronidazole (MET) or Ciprofloxacin/(CIP) was mixed with a polydioxanone (PDS)polymer solution at 5 and 25 wt% and processed into fibers. PDS fibers served as a control. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), tensile testing, and high-performance liquid chromatography (HPLC) were used to assess fiber morphology, chemical structure, mechanical properties, and drug release, respectively. Antimicrobial properties were evaluated against those of Porphyromonas gingivalis/Pg and Enterococcus faecalis/Ef. Cytotoxicity was assessed in human dental pulp stem cells (hDPSCs). Statistics were performed, and significance was set at the 5% level. SEM imaging revealed a submicron fiber diameter. FTIR confirmed antibiotic incorporation. The tensile values of hydrated 25 wt% CIP scaffold were significantly lower than those of all other groups. Analysis of HPLC data confirmed gradual, sustained drug release from the scaffolds over 48 hrs. CIP-containing scaffolds significantly (p regenerative endodontics.

  15. Towards improved scaffolds for bone tissue engineering

    NARCIS (Netherlands)

    Nandakumar, A.

    2012-01-01

    Tissue engineering aims to restore, maintain or improve tissue function of damaged tissues. In a classical set-up, a scaffold functions as a supporting structure and a carrier for growth factors and/or cells. Human mesenchymal stromal cells (hMSCs) have the ability to differentiate into bone, cartil

  16. Scaffolding of cystine-stabilized miniproteins

    NARCIS (Netherlands)

    Sankaran, S.; Stojanovic, Ivan; Barendregt, A.; Heck, A.J.R.; Schasfoort, Richardus B.M.; Jonkheijm, Pascal

    2016-01-01

    Biomolecular scaffolds were engineered by genetically fusing robust miniproteins in a sequence, like a chain. By fusing these miniprotein chains to a teal fluorescent protein (TFP), an efficient strategy was devised for their production in E. coli. Miniproteins that bind β-trypsin, VEGF and HIV-1

  17. A conceptualisation of whole-class scaffolding

    NARCIS (Netherlands)

    Smit, J.; van Eerde, H.A.A.; Bakker, A.

    2013-01-01

    The concept of scaffolding refers to temporary and adaptive support, originally in dyadic adult– child interaction. It has become widely used, also in whole-class settings, but often in loose ways. The aim of this paper is to theoretically and empirically ground a conceptualisation of whole-class sc

  18. Simulations as Scaffolds in Science Education

    DEFF Research Database (Denmark)

    Renken, Maggie; Peffer, Melanie; Otrel-Cass, Kathrin

    This book outlines key issues for addressing the grand challenges posed to educators, developers, and researchers interested in the intersection of simulations and science education. To achieve this, the authors explore the use of computer simulations as instructional scaffolds that provide strat...

  19. Membrane supported scaffold : architectures for tissue engineering

    NARCIS (Netherlands)

    Bettahalli, Narasimha Murthy Srivatsa

    2011-01-01

    Tissue engineering aims at restoring or regenerating a damaged tissue. Often the tissue recreation occurs by combining cells, derived from a patient biopsy, onto a 3D porous matrix, functioning as a scaffold. One of the current limitations of tissue engineering is the inability to provide sufficie

  20. Biodegradable elastomeric scaffolds for soft tissue engineering

    NARCIS (Netherlands)

    Pego, Ana Paula; Poot, André A.; Grijpma, Dirk W.; Feijen, Jan

    2003-01-01

    Elastomeric copolymers of 1,3-trimethylene carbonate (TMC) and ε-caprolactone (CL) and copolymers of TMC and D,L-lactide (DLLA) have been evaluated as candidate materials for the preparation of biodegradable scaffolds for soft tissue engineering. TMC-DLLA copolymers are amorphous and degrade more r

  1. Work Related Musculoskeletal Disorders in Scaffolders

    NARCIS (Netherlands)

    L.A.M. Elders (Leo)

    2003-01-01

    textabstractIn many occupational populations, musculoskeletal disorders constitute an important source of morbidity, sickness absence, and disability and attribute to a substantial social and economic burden for society. This is certainly applicable to scaffolders, the study population in this thesi

  2. Modeling Tissue Growth Within Nonwoven Scaffolds Pores

    Science.gov (United States)

    Church, Jeffrey S.; Alexander, David L.J.; Russell, Stephen J.; Ingham, Eileen; Ramshaw, John A.M.; Werkmeister, Jerome A.

    2011-01-01

    In this study we present a novel approach for predicting tissue growth within the pores of fibrous tissue engineering scaffolds. Thin nonwoven polyethylene terephthalate scaffolds were prepared to characterize tissue growth within scaffold pores, by mouse NR6 fibroblast cells. On the basis of measurements of tissue lengths at fiber crossovers and along fiber segments, mathematical models were determined during the proliferative phase of cell growth. Tissue growth at fiber crossovers decreased with increasing interfiber angle, with exponential relationships determined on day 6 and 10 of culture. Analysis of tissue growth along fiber segments determined two growth profiles, one with enhanced growth as a result of increased tissue lengths near the fiber crossover, achieved in the latter stage of culture. Derived mathematical models were used in the development of a software program to visualize predicted tissue growth within a pore. This study identifies key pore parameters that contribute toward tissue growth, and suggests models for predicting this growth, based on fibroblast cells. Such models may be used in aiding scaffold design, for optimum pore infiltration during the tissue engineering process. PMID:20687775

  3. Scaffolding English Language Learners' Reading Performance

    Science.gov (United States)

    McKenzie, Lolita D.

    2011-01-01

    English language learners (ELLs) spend a majority of their instructional time in mainstream classrooms with mainstream teachers. Reading is an area with which many ELLs are challenged when placed within mainstream classrooms. Scaffolding has been identified as one of the best teaching practices for helping students read. ELL students in a local…

  4. Scaffolding English Language Learners' Reading Performance

    Science.gov (United States)

    McKenzie, Lolita D.

    2011-01-01

    English language learners (ELLs) spend a majority of their instructional time in mainstream classrooms with mainstream teachers. Reading is an area with which many ELLs are challenged when placed within mainstream classrooms. Scaffolding has been identified as one of the best teaching practices for helping students read. ELL students in a local…

  5. Using Scaffolding to Scale-up Justifications

    Science.gov (United States)

    James, Carolyn; Casas, Ana; Grant, Douglas

    2016-01-01

    Open-ended mathematical tasks provide great opportunities for students to engage in authentic mathematical practices, such as conjecturing, generalizing, and justifying. Supporting students in open-ended tasks can be challenging. Appropriate scaffolding of a task has been linked to more opportunities for student learning and better student…

  6. Gestures: Silent Scaffolding within Small Groups

    Science.gov (United States)

    Carter, Glenda; Wiebe, Eric N.; Reid-Griffin, Angela

    2006-01-01

    This paper describes how gestures are used to enhance scaffolding that occurs in small group settings. Sixth and eighth grade students participated in an elective science course focused on earth science concepts with a substantial spatial visualization component. Gestures that students used in small group discussions were analyzed and four…

  7. Fluorescent composite scaffolds made of nanodiamonds/polycaprolactone

    Science.gov (United States)

    Cao, Li; Hou, Yanwen; Lafdi, Khalid; Urmey, Kirk

    2015-11-01

    Polycaprolactone (PCL) has been widely studied for biological applications. Biodegradable PCL fibrous scaffold can work as an appropriate substrate for tissue regeneration. In this letter, fluorescent nanodiamonds (FNDs) were prepared after surface passivation with octadecylamine. The FNDs were then mixed with PCL polymer and subsequently electrospun into FNDs/PCL fibrous scaffolds. The obtained scaffolds not only exhibited photoluminescence, but also showed reinforced mechanical strength. Toxicity study indicated FNDs/PCL scaffolds were nontoxic. This biocompatible fluorescent composite fibrous scaffold can support in vitro cell growth and also has the potential to act as an optical probe for tissue engineering application in vitro and in vivo.

  8. Preparation and cytocompatibility of silk fibroin /chitosan scaffolds

    Institute of Scientific and Technical Information of China (English)

    Zhen-ding SHE; Wei-qiang LIU; Qing-ling FENG

    2009-01-01

    One challenge in soft tissue engineering is to find an applicable scaffold, not only having suitable mechanical properties, porous structures, and biodegradable properties, but also being abundant in active groups and having good biocompatibility. In this study, a threedimensional silk fibroin/chitosan (SFCS) scaffold was successfully prepared with interconnected porous structure, excellent hydrophilicity, and proper mechanical properties. Compared with polylactic glycolic acid (PLGA) scaffold, the SFCS scaffold further facilitated the growth of HepG2 cells (human hepatoma cell line). Keeping the good cytocompatibility and combining the advantages of both fibroin and chitosan, the SFCS scaffold should be a prominent candidate for soft tissue engineering, for example, liver.

  9. Phage display selection of tight specific binding variants from a hyperthermostable Sso7d scaffold protein library.

    Science.gov (United States)

    Zhao, Ning; Schmitt, Margaret A; Fisk, John D

    2016-04-01

    Antibodies, the quintessential biological recognition molecules, are not ideal for many applications because of their large size, complex modifications, and thermal and chemical instability. Identifying alternative scaffolds that may be evolved into tight, specific binding molecules with improved physical properties is of increasing interest, particularly for biomedical applications in resource-limited environments. Hyperthermophilic organisms, such as Sulfolobus solfataricus, are an attractive source of highly stable proteins that may serve as starting points for alternative molecular recognition scaffolds. We describe the first application of phage display to identify binding proteins based on the S. solfataricus protein Sso7d scaffold. Sso7d is a small cysteine-free DNA-binding protein (approximately 7 kDa, 63 amino acids), with a melting temperature of nearly 100 °C. Tight-binding Sso7d variants were selected for a diverse set of protein targets from a 10(10) member library, demonstrating the versatility of the scaffold. These Sso7d variants are able to discriminate among closely related human, bovine and rabbit serum albumins. Equilibrium dissociation constants in the nanomolar to low micromolar range were measured via competitive ELISA. Importantly, the Sso7d variants continue to bind their targets in the absence of the phage context. Furthermore, phage-displayed Sso7d variants retain their binding affinity after exposure to temperatures up to 70 °C. Taken together, our results suggest that the Sso7d scaffold will be a complementary addition to the range of non-antibody scaffold proteins that may be utilized in phage display. Variants of hyperthermostable binding proteins have potential applications in diagnostics and therapeutics for environments with extreme conditions of storage and deployment.

  10. RELATIONSHIP OF LEFT VENTRICULAR SIZE TO LEFT ATRIAL AND LEFT ATRIAL APPENDAGE SIZE IN SINUS RHYTHM PATIENTS WITH DILATED CARDIOMYOPATHY

    Science.gov (United States)

    Bakalli, Aurora; Georgievska-Ismail, Ljubica; Musliu, Nebi; Koçinaj, Dardan; Gashi, Zaim; Zeqiri, Nexhmi

    2012-01-01

    Introduction: Thromboembolic events are a frequent cause of mortality in patients with congestive heart failure. The aim of or study was to evaluate the relationship of left ventricular end diastolic diameter (LVEDD) to left atrial (LA) size and left atrial appendage (LAA) size in patients with dilated cardiomyopathy in sinus rhythm, as well as to determine the prevalence of thrombi in LV and LA /LAA. Methods: This was a prospective cross-sectional study, conducted from December 2009 until December 2011. The study included 95 patients with dilated cardiomyopathy in sinus rhythm. Patients with swallowing problems, acute myocardial infarction, atrial fibrillation/flatter, severe systolic dysfunction, and/or patients who were taking oral anticoagulation therapy were excluded. Results: Mean patient age was 58.6 ± 12.2 years and 68.4% were men. Mean LVEDD of our population was 66.5 ± 6.5 mm, while mean LA atrium, LA volume and LAA maximal area were 46 ± 5.1 mm, 87.2 ± 38.7 cm3 and 4.7 ± 1.2 cm2, respectively. LA diameter (p<0.001) and LAA maximal area (p=0.01) showed to be independent predictors of LV size. LV thrombus was detected in 13 (13.7%) patients, while LAA thrombus in 46 (48.4%) patients of our study population. Conclusions: In conclusion, dilated LV size is associated with enlarged LA and LAA size. On the other hand, dilation of LV, LA and LAA is related to high prevalence of left chamber cardiac thrombi. PMID:23322961

  11. Early results of first versus second generation Amplatzer occluders for left atrial appendage closure in patients with atrial fibrillation.

    Science.gov (United States)

    Gloekler, Steffen; Shakir, Samera; Doblies, Janosch; Khattab, Ahmed A; Praz, Fabien; Guerios, Ênio; Koermendy, Dezsoe; Stortecky, Stefan; Pilgrim, Thomas; Buellesfeld, Lutz; Wenaweser, Peter; Windecker, Stephan; Moschovitis, Aris; Jaguszewski, Milosz; Landmesser, Ulf; Nietlispach, Fabian; Meier, Bernhard

    2015-08-01

    Transcatheter left atrial appendage (LAA) occlusion has been proven to be an effective treatment for stroke prophylaxis in patients with atrial fibrillation. For this purpose, the Amplatzer cardiac plug (ACP) was introduced. Its second generation, the Amulet, was developed for easier delivery, better coverage, and reduction of complications. To investigate the safety and efficacy of first generation versus second generation Amplatzer occluders for LAA occlusion. Retrospective analysis of prospectively collected data from the LAA occlusion registries of the Bern and Zurich university hospitals. Comparison of the last consecutive 50 ACP cases versus the first consecutive 50 Amulet cases in patients with non-valvular atrial fibrillation. For safety, a periprocedural combined endpoint, which is composed of death, stroke, cardiac tamponade, and bailout by surgery was predefined. For efficacy, the endpoint was procedural success. There were no differences between the two groups in baseline characteristics. The percentage of associated interventions during LAA occlusion was high in (78% with ACP vs. 70% with Amulet p = ns). Procedural success was similar in both groups (98 vs. 94%, p = 0.61). The combined safety endpoint for severe adverse events was reached by a similar rate of patients in both groups (6 vs. 8%, p = 0.7). Overall complication rate was insignificantly higher in the ACP group, which was mainly driven by clinically irrelevant pericardial effusions (24 vs. 14%, p = 0.31). Death, stroke, or tamponade were similar between the groups (0 vs. 2%, 0 vs. 0%, or 6 vs. 6%, p = ns). Transcatheter LAA occlusion for stroke prophylaxis in patients with atrial fibrillation can be performed with similarly high success rates with first and second generations of Amplatzer occluders. According to this early experience, the Amulet has failed to improve results of LAA occlusion. The risk for major procedural adverse events is acceptable but has to be taken into account when

  12. Intracardiac Echocardiography From the Left Atrium for Procedural Guidance of Transcatheter Left Atrial Appendage Occlusion.

    Science.gov (United States)

    Korsholm, Kasper; Jensen, Jesper Møller; Nielsen-Kudsk, Jens Erik

    2017-08-24

    The aim of this study was to compare the efficacy and safety of intracardiac echocardiography (ICE) from the left atrium (LA) with transesophageal echocardiography (TEE) for procedural guidance of transcatheter left atrial appendage occlusion (LAAO). TEE with general anesthesia is the current gold standard to guide LAAO. By the use of ICE from the LA, LAAO can be performed in local anesthesia and may potentially have advantages over TEE. A single-center, cohort study of patients undergoing LAAO with the Amplatzer Cardiac Plug or Amulet (St. Jude Medical, St. Paul, Minnesota). Procedures were guided by ICE from the LA with local anesthesia (n = 109) or TEE using general anesthesia (n = 107). All patients had pre-procedural cardiac computed tomography. Efficacy outcomes were technical success, procedural success, and peridevice leakage at TEE 8 weeks after LAAO. Safety outcome was a composite of periprocedural complications. Technical success was achieved in 99% of both the TEE and ICE group. Procedural success was similar between groups: 94.4% success rate in the TEE-guided group, and 94.5% in the ICE-guided group. Major periprocedural complications occurred in 4.7% of the TEE group and 1.8% of the ICE group. Rate and degree of peridevice leak did not differ between groups at follow-up. Turnover time in the catheter laboratory, and contrast use were reduced with ICE. LA ICE to guide LAAO as compared with TEE appears to be effective and safe, without increased procedure-related complications. The rate of peridevice leak is low and similar to TEE-guided procedures. Time spent in the catheterization room may decrease substantially. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  13. Left atrial appendage closure using the Amulet device: an initial experience with the second generation amplatzer cardiac plug.

    Science.gov (United States)

    Lam, Simon Cheung Chi; Bertog, Stefan; Gafoor, Sameer; Vaskelyte, Laura; Boehm, Patrick; Ho, Raymond Wei Jian; Franke, Jennifer; Hofmann, Ilona; Sievert, Horst

    2015-02-01

    Aim of this study was to demonstrate the feasibility, safety, and short-term outcome of left atrial appendage (LAA) closure with a new generation LAA closure device. The Amulet device (AGA, St Jude Medical, Minneapolis, MN) is a new generation of the amplatzer cardiac plug (ACP), specifically designed for LAA closure. This new version is designed to facilitate the implantation process and minimize procedural or device-related complications. The device was implanted in 17 patients with nonvalvular atrial fibrillation (AF). Clinical data were obtained at baseline, during the procedure, at discharge, at 30 and 90 days. All devices were implanted successfully. Device sizes ranged from 20 mm to 31 mm. A 12 French (Fr) or 14 Fr delivery sheath was used depending on the selected device size. Full and partial recapture was performed in 1 case and 3 cases, respectively. There was 1 procedure-related pericardial effusion successfully managed with pericardiocentesis. There was no device embolization. The mean length of stay was 2.1 ± 0.3 days. At 90 days, there were no deaths, strokes, systemic thromboembolism, or bleeding complications. There was no device-related thrombus or pericardial effusion at 90-day TEE. In 2 of the 17 patients minimal peridevice flow (smaller than 2 mm) was present. The Amulet device, which has new novel features as compared with the first generation ACP, is a feasible option for LAA closure. From our initial experience, implantation of the Amulet is associated with high success rate and good short-term outcome. © 2014 Wiley Periodicals, Inc.

  14. Safety and efficacy of catheter-based left atrial appendage closure in patients with contraindications for long-term anticoagulation.

    Science.gov (United States)

    Seidel, Adrian; Parwani, Abdul S; Krackhardt, Florian; Huemer, Martin; Attanasio, Philipp; Haverkamp, Wilhelm; Pieske, Burkert; Boldt, Leif-Hendrik

    2017-05-31

    Percutaneous left atrial appendage closure (LAAC) and the role of post interventional anticoagulation often evokes controversy in daily practice. This study aimed to evaluate LAAC in patients with non-rheumatic atrial fibrillation, high thromboembolic risk and contraindications for long-term anticoagulation in a clinical scenario. Between 2010-2015, LAAC was attempted in 118 patients (47 women). Devices were successfully implanted in 95% (Watchman™ device n=97, St. Amplatzer™ Cardiac Plug/Amulet n=14, Amplatzer PFO Occluder n=1). Mean age, HAS-BLED and CHA2DS2VASc score were 75 years (SD 8.35yrs), 4.3 and 4.9, respectively. Median followup was 447 days (P25=183d, P75=789d). The primary safety endpoint was defined as major bleeding according to the International Society on Thrombosis and Haemostasis. The combined efficacy endpoint included ischemic strokes, transitory ischemic attacks (TIA) and systemic embolisms. Procedural complication rate was 3.4%. After successful intervention, either a therapy with anticoagulants (n=62) or dual antiplatelet therapy (DAPT, n=50) was prescribed temporarily. Medication was reduced if implantation proved satisfying in a 6-week follow-up transesophageal echocardiography, which was the case in 79% of these patients. During follow-up, one patient suffered a TIA (0.6%/year). No other efficacy event was observed. 11 major bleedings occurred (6.6%/year): one each under DAPT plus phenprocoumon, DAPT plus rivaroxaban, acetylsalicylic acid (ASA) plus rivaroxaban, two under DAPT, two under ASA plus low molecular weight heparin, and four under ASA only. In our analysis, catheter-based LAA occlusion prevented thromboembolisms with high efficacy. Major bleedings were however common in patients with, but also without anticoagulation, independent from time course.

  15. Parameterizing the Transport Pathways for Cell Invasion in Complex Scaffold Architectures

    Science.gov (United States)

    Ashworth, Jennifer C.; Mehr, Marco; Buxton, Paul G.; Best, Serena M.

    2016-01-01

    Interconnecting pathways through porous tissue engineering scaffolds play a vital role in determining nutrient supply, cell invasion, and tissue ingrowth. However, the global use of the term “interconnectivity” often fails to describe the transport characteristics of these pathways, giving no clear indication of their potential to support tissue synthesis. This article uses new experimental data to provide a critical analysis of reported methods for the description of scaffold transport pathways, ranging from qualitative image analysis to thorough structural parameterization using X-ray Micro-Computed Tomography. In the collagen scaffolds tested in this study, it was found that the proportion of pore space perceived to be accessible dramatically changed depending on the chosen method of analysis. Measurements of % interconnectivity as defined in this manner varied as a function of direction and connection size, and also showed a dependence on measurement length scale. As an alternative, a method for transport pathway parameterization was investigated, using percolation theory to calculate the diameter of the largest sphere that can travel to infinite distance through a scaffold in a specified direction. As proof of principle, this approach was used to investigate the invasion behavior of primary fibroblasts in response to independent changes in pore wall alignment and pore space accessibility, parameterized using the percolation diameter. The result was that both properties played a distinct role in determining fibroblast invasion efficiency. This example therefore demonstrates the potential of the percolation diameter as a method of transport pathway parameterization, to provide key structural criteria for application-based scaffold design. PMID:26888449

  16. Incorporation of chitosan microspheres into collagen-chitosan scaffolds for the controlled release of nerve growth factor.

    Directory of Open Access Journals (Sweden)

    Wen Zeng

    Full Text Available Artifical nerve scaffold can be used as a promising alternative to autologous nerve grafts to enhance the repair of peripheral nerve defects. However, current nerve scaffolds lack efficient microstructure and neurotrophic support.Microsphere-Scaffold composite was developed by incorporating chitosan microspheres loaded with nerve growth factor (NGF-CMSs into collagen-chitosan scaffolds (CCH with longitudinally oriented microchannels (NGF-CMSs/CCH. The morphological characterizations, in vitro release kinetics study, neurite outgrowth assay, and bioactivity assay were evaluated. After that, a 15-mm-long sciatic nerve gap in rats was bridged by the NGF-CMSs/CCH, CCH physically absorbed NGF (NGF/CCH, CCH or nerve autograft. 16 weeks after implantation, electrophysiology, fluoro-gold retrograde tracing, and nerve morphometry were performed.The NGF-CMSs were evenly distributed throughout the longitudinally oriented microchannels of the scaffold. The NGF-CMSs/CCH was capable of sustained release of bioactive NGF within 28 days as compared with others in vitro. In vivo animal study demonstrated that the outcomes of NGF-CMSs/CCH were better than those of NGF/CCH or CCH.Our findings suggest that incorporation of NGF-CMSs into the CCH may be a promising tool in the repair of peripheral nerve defects.

  17. Engineering anatomically shaped vascularized bone grafts with hASCs and 3D-printed PCL scaffolds.

    Science.gov (United States)

    Temple, Joshua P; Hutton, Daphne L; Hung, Ben P; Huri, Pinar Yilgor; Cook, Colin A; Kondragunta, Renu; Jia, Xiaofeng; Grayson, Warren L

    2014-12-01

    The treatment of large craniomaxillofacial bone defects is clinically challenging due to the limited availability of transplantable autologous bone grafts and the complex geometry of the bones. The ability to regenerate new bone tissues that faithfully replicate the anatomy would revolutionize treatment options. Advances in the field of bone tissue engineering over the past few decades offer promising new treatment alternatives using biocompatible scaffold materials and autologous cells. This approach combined with recent advances in three-dimensional (3D) printing technologies may soon allow the generation of large, bioartificial bone grafts with custom, patient-specific architecture. In this study, we use a custom-built 3D printer to develop anatomically shaped polycaprolactone (PCL) scaffolds with varying internal porosities. These scaffolds are assessed for their ability to support induction of human adipose-derived stem cells (hASCs) to form vasculature and bone, two essential components of functional bone tissue. The development of functional tissues is assessed in vitro and in vivo. Finally, we demonstrate the ability to print large mandibular and maxillary bone scaffolds that replicate fine details extracted from patient's computed tomography scans. The findings of this study illustrate the capabilities and potential of 3D printed scaffolds to be used for engineering autologous, anatomically shaped, vascularized bone grafts.

  18. Migration Capacity and Viability of Human Primary Osteoblasts in Synthetic Three-dimensional Bone Scaffolds Made of Tricalciumphosphate

    Directory of Open Access Journals (Sweden)

    Hermann Seitz

    2011-07-01

    Full Text Available In current therapeutic strategies, bone defects are filled up by bone auto- or allografts. Since they are limited by insufficient availability and donor site morbidity, it is necessary to find an appropriate alternative of synthetic porous bone materials. Because of their osteoconductive characteristics, ceramic materials like tricalciumphosphate (TCP are suitable to fill up bone defects. Another advantage of TCP implants is the ability of patient-specific engineering. Objective of the present in-vitro study was to analyze the migration capacity and viability of human primary osteoblasts in porous three-dimensional TCP scaffolds in a static cell culture. To obtain data of the cellular supply with nutrients and oxygen, we determined the oxygen concentration and the pH value within the 3D scaffold compared to the surrounding medium using microsensors. After eight days of cultivation we found cells on all four planes. During incubation, the oxygen concentration within the scaffold decreased by approximately 8%. Furthermore, we could not demonstrate an increasing acidification in the core of the TCP scaffold. Our results suggest that osteoblasts could migrate and survive within the macroporous TCP scaffolds. The selected size of the macropores prevents overgrowth of cells, whereby the oxygen and nutrients supply is sufficiently guaranteed.

  19. Piezoelectric PU/PVDF electrospun scaffolds for wound healing applications.

    Science.gov (United States)

    Guo, Hong-Feng; Li, Zhen-Sheng; Dong, Shi-Wu; Chen, Wei-Jun; Deng, Ling; Wang, Yu-Fei; Ying, Da-Jun

    2012-08-01

    Previous studies have shown that piezoelectric materials may be used to prepare bioactive electrically charged surfaces. In the current study, polyurethane/polyvinylidene fluoride (PU/PVDF) scaffolds were prepared by electrospinning. The mechanical property and piezoelectric property of the scaffolds were evaluated. The crystalline phase of PVDF in the scaffolds was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). In vitro cell culture was performed to investigate cytocompatibility of the scaffolds. Wound-healing assay, cell-adhesion assay, quantitative RT-PCR and Western blot analyses were performed to investigate piezoelectric effect of the scaffolds on fibroblast activities. Further, the scaffolds were subcutaneously implanted in Sprague-Dawley (SD) rats to investigate their biocompatibility and the piezoelectric effect on fibrosis in vivo. The results indicated that the electrospinning process had changed PVDF crystalline phase from the nonpiezoelectric α phase to the piezoelectric β phase. The fibroblasts cultured on the scaffolds showed normal morphology and proliferation. The fibroblasts cultured on the piezoelectric-excited scaffolds showed enhanced migration, adhesion and secretion. The scaffolds that were subcutaneously implanted in SD rats showed higher fibrosis level due to the piezoelectrical stimulation, which was caused by random animal movements followed by mechanical deformation of the scaffolds. The scaffolds are potential candidates for wound healing applications.

  20. Characterization of mineralized collagen-glycosaminoglycan scaffolds for bone regeneration.

    Science.gov (United States)

    Kanungo, Biraja P; Silva, Emilio; Van Vliet, Krystyn; Gibson, Lorna J

    2008-05-01

    Mineralized collagen-glycosaminoglycan scaffolds designed for bone regeneration have been synthesized via triple co-precipitation in the absence of a titrant phase. Here, we characterize the microstructural and mechanical properties of these newly developed scaffolds with 50 and 75 wt.% mineral content. The 50 wt.% scaffold had an equiaxed pore structure with isotropic mechanical properties and a Ca-P-rich mineral phase comprised of brushite; the 75 wt.% scaffold had a bilayer structure with a pore size varying in the through-thickness direction and a mineral phase comprised of 67% brushite and 33 wt.% monetite. The compressive stress-strain response of the scaffolds was characteristic of low-density open-cell foams with distinct linear elastic, collapse plateau and densification regimes. The elastic modulus and strength of individual struts within the scaffolds were measured using an atomic force microscopy cantilevered beam-bending technique and compared with the composite response under indentation and unconfined compression. Cellular solids models, using the measured strut properties, overestimated the overall mechanical properties for the scaffolds; the discrepancy arises from defects such as disconnected pore walls within the scaffold. As the scaffold stiffness and strength decreased with increasing overall mineral content and were less than that of natural, mineralized collagen scaffolds, these microstructural/mechanical relations will be used to further improve scaffold design for bone regeneration applications.

  1. Fabrication and Mechanical Characterization of Hydrogel Infused Network Silk Scaffolds

    Science.gov (United States)

    Kundanati, Lakshminath; Singh, Saket K.; Mandal, Biman B.; Murthy, Tejas G.; Gundiah, Namrata; Pugno, Nicola M.

    2016-01-01

    Development and characterization of porous scaffolds for tissue engineering and regenerative medicine is of great importance. In recent times, silk scaffolds were developed and successfully tested in tissue engineering and drug release applications. We developed a novel composite scaffold by mechanical infusion of silk hydrogel matrix into a highly porous network silk scaffold. The mechanical behaviour of these scaffolds was thoroughly examined for their possible use in load bearing applications. Firstly, unconfined compression experiments show that the denser composite scaffolds displayed significant enhancement in the elastic modulus as compared to either of the components. This effect was examined and further explained with the help of foam mechanics principles. Secondly, results from confined compression experiments that resemble loading of cartilage in confinement, showed nonlinear material responses for all scaffolds. Finally, the confined creep experiments were performed to calculate the hydraulic permeability of the scaffolds using soil mechanics principles. Our results show that composite scaffolds with some modifications can be a potential candidate for use of cartilage like applications. We hope such approaches help in developing novel scaffolds for tissue engineering by providing an understanding of the mechanics and can further be used to develop graded scaffolds by targeted infusion in specific regions. PMID:27681725

  2. Fabrication and Mechanical Characterization of Hydrogel Infused Network Silk Scaffolds

    Directory of Open Access Journals (Sweden)

    Lakshminath Kundanati

    2016-09-01

    Full Text Available Development and characterization of porous scaffolds for tissue engineering and regenerative medicine is of great importance. In recent times, silk scaffolds were developed and successfully tested in tissue engineering and drug release applications. We developed a novel composite scaffold by mechanical infusion of silk hydrogel matrix into a highly porous network silk scaffold. The mechanical behaviour of these scaffolds was thoroughly examined for their possible use in load bearing applications. Firstly, unconfined compression experiments show that the denser composite scaffolds displayed significant enhancement in the elastic modulus as compared to either of the components. This effect was examined and further explained with the help of foam mechanics principles. Secondly, results from confined compression experiments that resemble loading of cartilage in confinement, showed nonlinear material responses for all scaffolds. Finally, the confined creep experiments were performed to calculate the hydraulic permeability of the scaffolds using soil mechanics principles. Our results show that composite scaffolds with some modifications can be a potential candidate for use of cartilage like applications. We hope such approaches help in developing novel scaffolds for tissue engineering by providing an understanding of the mechanics and can further be used to develop graded scaffolds by targeted infusion in specific regions.

  3. Influence of scaffold design on 3D printed cell constructs.

    Science.gov (United States)

    Souness, Auryn; Zamboni, Fernanda; Walker, Gavin M; Collins, Maurice N

    2017-02-14

    Additive manufacturing is currently receiving significant attention in the field of tissue engineering and biomaterial science. The development of precise, affordable 3D printing technologies has provided a new platform for novel research to be undertaken in 3D scaffold design and fabrication. In the past, a number of 3D scaffold designs have been fabricated to investigate the potential of a 3D printed scaffold as a construct which could support cellular life. These studies have shown promising results; however, few studies have utilized a low-cost desktop 3D printing technology as a potential rapid manufacturing route for different scaffold designs. Here six scaffold designs were manufactured using a Fused deposition modeling, a "bottom-up" solid freeform fabrication approach, to determine optimal scaffold architecture for three-dimensional cell growth. The scaffolds, produced from PLA, are coated using pullulan and hyaluronic acid to assess the coating influence on cell proliferation and metabolic rate. Scaffolds are characterized both pre- and postprocessing using water uptake analysis, mechanical testing, and morphological evaluation to study the inter-relationships between the printing process, scaffold design, and scaffold properties. It was found that there were key differences between each scaffold design in terms of porosity, diffusivity, swellability, and compressive strength. An optimal design was chosen based on these physical measurements which were then weighted in accordance to design importance based on literature and utilizing a design matrix technique. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

  4. Fabrication of polymeric scaffolds with a controlled distribution of pores.

    Science.gov (United States)

    Capes, J S; Ando, H Y; Cameron, R E

    2005-12-01

    The design of tissue engineering scaffolds must take into account many factors including successful vascularisation and the growth of cells. Research has looked at refining scaffold architecture to promote more directed growth of tissues through well-defined anisotropy in the pore structure. In many cases it is also desirable to incorporate therapeutic ingredients, such as growth factors, into the scaffold so that their release occurs as the scaffold degrades. Therefore, scaffold fabrication techniques must be found to precisely control, not only the overall porosity of scaffolds, but also the pore size, shape and spatial distribution. This work describes the use of a regularly shaped porogen, sugar spheres, to manufacture polymeric scaffolds. Results show that pre-assembling the spheres created scaffolds with a constant porosity of 60%, but with varying pores sizes from 200-800 microm, leading to a variation in the surface area and likely degradation rate of the scaffolds. Employing different polymer impregnation techniques tailored the number of pores present with a diameter of less than 100 microm to suit different functions, and altering the packing structure of the sugar spheres created scaffolds with novel layered porosity. Replacing sugar spheres with sugar strands formed scaffolds with pores aligned in one direction.

  5. Porous Three-Dimensional Carbon Nanotube Scaffolds for Tissue Engineering

    Science.gov (United States)

    Lalwani, Gaurav; Gopalan, Anu; D’Agati, Michael; Sankaran, Jeyantt Srinivas; Judex, Stefan; Qin, Yi-Xian; Sitharaman, Balaji

    2015-01-01

    Assembly of carbon nanomaterials into three-dimensional (3D) architectures is necessary to harness their unique physiochemical properties for tissue engineering and regenerative medicine applications. Herein, we report the fabrication and comprehensive cytocompatibility assessment of 3D chemically crosslinked macro-sized (5–8 mm height and 4–6 mm diameter) porous carbon nanotube (CNT) scaffolds. Scaffolds prepared via radical initiated thermal crosslinking of single- or multi- walled CNTs (SWCNTs and MWCNTs) possess high porosity (>80%), and nano-, micro- and macro-scale interconnected pores. MC3T3 pre-osteoblast cells on MWCNT and SWCNT scaffolds showed good cell viability comparable to poly(lactic-co-glycolic) acid (PLGA) scaffolds after 5 days. Confocal live cell and immunofluorescence imaging showed that MC3T3 cells were metabolically active and could attach, proliferate and infiltrate MWCNT and SWCNT scaffolds. SEM imaging corroborated cell attachment and spreading and suggested that cell morphology is governed by scaffold surface roughness. MC3T3 cells were elongated on scaffolds with high surface roughness (MWCNTs) and rounded on scaffolds with low surface roughness (SWCNTs). The surface roughness of scaffolds may be exploited to control cellular morphology, and in turn govern cell fate. These results indicate that crosslinked MWCNTs and SWCNTs scaffolds are cytocompatible, and open avenues towards development of multifunctional all-carbon scaffolds for tissue engineering applications. PMID:25788440

  6. Bone regeneration in 3D printing bioactive ceramic scaffolds with improved tissue/material interface pore architecture in thin-wall bone defect.

    Science.gov (United States)

    Shao, Huifeng; Ke, Xiurong; Liu, An; Sun, Miao; He, Yong; Yang, Xianyan; Fu, Jianzhong; Liu, Yanming; Zhang, Lei; Yang, Guojing; Xu, Sanzhong; Gou, Zhongru

    2017-03-13

    Three-dimensional (3D) printing bioactive ceramics have demonstrated alternative approaches to bone tissue repair, but an optimized materials system for improving the recruitment of host osteogenic cells into the bone defect and enhancing targeted repair of the thin-wall craniomaxillofacial defects remains elusive. Herein we systematically evaluated the role of side-wall pore architecture in the direct-ink-writing bioceramic scaffolds on mechanical properties and osteogenic capacity in rabbit calvarial defects. The pure calcium silicate (CSi) and dilute Mg-doped CSi (CSi-Mg6) scaffolds with different layer thickness and macropore sizes were prepared by varying the layer deposition mode from single-layer printing (SLP) to double-layer printing (DLP) and then by undergoing one-, or two-step sintering. It was found that the dilute Mg doping and/or two-step sintering schedule was especially beneficial for improving the compressive strength (~25‒104 MPa) and flexural strength (~6‒18 MPa) of the Ca-silicate scaffolds. The histological analysis for the calvarial bone specimens in vivo revealed that the SLP scaffolds had a high osteoconduction at the early stage (4 weeks) but the DLP scaffolds displayed a higher osteogenic capacity for a long time stage (8~12 weeks). Although the DLP CSi scaffolds displayed somewhat higher osteogenic capacity at 8 and 12 weeks, the DLP CSi-Mg6 scaffolds with excellent fracture resistance also showed appreciable new bone tissue ingrowth. These findings demonstrate that the side-wall pore architecture in 3D printed bioceramic scaffolds is required to optimize for bone repair in calvarial bone defects, and especially the Mg doping wollastontie is promising for 3D printing thin-wall porous scaffolds for craniomaxillofacial bone defect treatment.

  7. Improving osteointegration and osteogenesis of three-dimensional porous Ti6Al4V scaffolds by polydopamine-assisted biomimetic hydroxyapatite coating.

    Science.gov (United States)

    Li, Yong; Yang, Wei; Li, Xiaokang; Zhang, Xing; Wang, Cairu; Meng, Xiangfei; Pei, Yifeng; Fan, Xiangli; Lan, Pingheng; Wang, Chunhui; Li, Xiaojie; Guo, Zheng

    2015-03-18

    Titanium alloys with various porous structures can be fabricated by advanced additive manufacturing techniques, which are attractive for use as scaffolds for bone defect repair. However, modification of the scaffold surfaces, particularly inner surfaces, is critical to improve the osteointegration of these scaffolds. In this study, a biomimetic approach was employed to construct polydopamine-assisted hydroxyapatite coating (HA/pDA) onto porous Ti6Al4V scaffolds fabricated by the electron beam melting method. The surface modification was characterized with the field emission scanning electron microscopy, energy dispersive spectroscopy, water contact angle measurement, and confocal laser scanning microscopy. Attachment and proliferation of MC3T3-E1 cells on the scaffold surface were significantly enhanced by the HA/pDA coating compared to the unmodified surfaces. Additionally, MC3T3-E1 cells grown on the HA/pDA-coated Ti6Al4V scaffolds displayed significantly higher expression of runt-related transcription factor-2, alkaline phosphatase, osteocalcin, osteopontin, and collagen type-1 compared with bare Ti6Al4V scaffolds after culture for 14 days. Moreover, microcomputed tomography analysis and Van-Gieson staining of histological sections showed that HA/pDA coating on surfaces of porous Ti6Al4V scaffolds enhanced osteointegration and significantly promoted bone regeneration after implantation in rabbit femoral condylar defects for 4 and 12 weeks. Therefore, this study provides an alternative to biofunctionalized porous Ti6Al4V scaffolds with improved osteointegration and osteogenesis functions for orthopedic applications.

  8. Association of electrospinning with electrospraying: a strategy to produce 3D scaffolds with incorporated stem cells for use in tissue engineering.

    Science.gov (United States)

    Braghirolli, Daikelly Iglesias; Zamboni, Fernanda; Acasigua, Gerson A X; Pranke, Patricia

    2015-01-01

    In tissue engineering, a uniform cell occupation of scaffolds is crucial to ensure the success of tissue regeneration. However, this point remains an unsolved problem in 3D scaffolds. In this study, a direct method to integrate cells into fiber scaffolds was investigated by combining the methods of electrospinning of fibers and bioelectrospraying of cells. With the associating of these methods, the cells were incorporated into the 3D scaffolds while the fibers were being produced. The scaffolds containing cells (SCCs) were produced using 20% poly(lactide-co-glycolide) solution for electrospinning and mesenchymal stem cells from deciduous teeth as a suspension for bioelectrospraying. After their production, the SCCs were cultivated for 15 days at 37°C with an atmosphere of 5% CO2. The 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide test demonstrated that the cells remained viable and were able to grow between the fibers. Scanning electron microscopy showed the presence of a high number of cells in the structure of the scaffolds and confocal images demonstrated that the cells were able to adapt and spread between the fibers. Histological analysis of the SCCs after 1 day of cultivation showed that the cells were uniformly distributed throughout the thickness of the scaffolds. Some physicochemical properties of the scaffolds were also investigated. SCCs exhibited good mechanical properties, compatible with their handling and further implantation. The results obtained in the present study suggest that the association of electrospinning and bioelectrospraying provides an interesting tool for forming 3D cell-integrated scaffolds, making it a viable alternative for use in tissue engineering.

  9. Recent developments in scaffold-guided cartilage tissue regeneration.

    Science.gov (United States)

    Liao, Jinfeng; Shi, Kun; Ding, Qiuxia; Qu, Ying; Luo, Feng; Qian, Zhiyong

    2014-10-01

    Articular cartilage repair is one of the most challenging problems in biomedical engineering because the regenerative capacity of cartilage is intrinsically poor. The lack of efficient treatment modalities motivates researches into cartilage tissue engineering such as combing cells, scaffolds and growth factors. In this review we summarize the current developments on scaffold systems available for cartilage tissue engineering. The factors that are critical to successfully design an ideal scaffold for cartilage regeneration were discussed. Then we present examples of selected material types (natural polymers and synthetic polymers) and fabricated forms of the scaffolds (three-dimensional scaffolds, micro- or nanoparticles, and their composites). In the end of review, we conclude with an overview of the ways in which biomedical nanotechnology is widely applied in cartilage tissue engineering, especially in the design of composite scaffolds. This review attempts to provide recommendations on the combination of qualities that would produce the ideal scaffold system for cartilage tissue engineering.

  10. Preparation of bioactive porous HA/PCL composite scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, J.; Guo, L.Y.; Yang, X.B. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Weng, J. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)], E-mail: jweng@swjtu.cn

    2008-12-30

    Porous hydroxyapatite (HA) bioceramic scaffold has been widely attracted the attention to act as a three-dimensional (3D) template for cell adhesion, proliferation, differentiation and thus promoting bone and cartilage regeneration because of its osteoinduction. However, the porous bioceramic scaffold is fragile so that it is not suitable to be applied in clinic for bone repair or replacement. Therefore, it is significant to improve the mechanical property of porous HA bioceramics while the interconnected structure is maintained for tissue ingrowth in vivo. In the present research, a porous composite scaffold composed of HA scaffold and polycaprolactone (PCL) lining was fabricated by the method of polymer impregnating to produce HA scaffold coated with PCL lining. Subsequently, the composite scaffolds were deposited with biomimetic coating for improving the bioactivity. The HA/PCL composite scaffolds with improved mechanical property and bioactivity is expected to be a promising bone substitute in tissue engineering applications.

  11. Preparation of bioactive porous HA/PCL composite scaffolds

    Science.gov (United States)

    Zhao, J.; Guo, L. Y.; Yang, X. B.; Weng, J.

    2008-12-01

    Porous hydroxyapatite (HA) bioceramic scaffold has been widely attracted the attention to act as a three-dimensional (3D) template for cell adhesion, proliferation, differentiation and thus promoting bone and cartilage regeneration because of its osteoinduction. However, the porous bioceramic scaffold is fragile so that it is not suitable to be applied in clinic for bone repair or replacement. Therefore, it is significant to improve the mechanical property of porous HA bioceramics while the interconnected structure is maintained for tissue ingrowth in vivo. In the present research, a porous composite scaffold composed of HA scaffold and polycaprolactone (PCL) lining was fabricated by the method of polymer impregnating to produce HA scaffold coated with PCL lining. Subsequently, the composite scaffolds were deposited with biomimetic coating for improving the bioactivity. The HA/PCL composite scaffolds with improved mechanical property and bioactivity is expected to be a promising bone substitute in tissue engineering applications.

  12. 3-D loaded scaffolds obtained by supercritical CO2 assisted process

    Science.gov (United States)

    Cardea, S.; Reverchon, E.

    2014-08-01

    In this work, a supercritical CO2 (SC-CO2) drying process for the formation of 3-D PVDF-HFP loaded scaffolds was tested. Experiments at pressures ranging between 150 and 250 bar and at temperatures ranging between 35 and 55°C were performed. The PVDF-HFP- acetone-ethanol solution at 15% w/w polymer was selected as the base case. The drug (amoxicillin) concentration was varied from 20 to 30% w/w with respect to PVDF-HFP. SC- CO2 drying process was confirmed to be a valid alternative to generate loaded structures; indeed, scaffolds characterized by nanometric networks (with mean pore diameter of about 300 nm) with a homogeneous drug distribution were obtained. Drug controlled release experiments were also performed and a quasi-zero order release kinetic was observed.

  13. Urethral tissue regeneration using collagen scaffold modified with collagen binding VEGF in a beagle model.

    Science.gov (United States)

    Jia, Weisheng; Tang, He; Wu, Jianjian; Hou, Xianglin; Chen, Bing; Chen, Wei; Zhao, Yannan; Shi, Chunying; Zhou, Feng; Yu, Wei; Huang, Shengquan; Ye, Gang; Dai, Jianwu

    2015-11-01

    Extensive urethral defects have a serious impact on quality of life, and treatment is challenging. A shortage of material for reconstruction is a key limitation. Improving the properties of biomaterials and making them suitable for urethral reconstruction will be helpful. Previously, we constructed a fusion protein, collagen-binding VEGF (CBD-VEGF), which can bind to collagen scaffold, stimulate cell proliferation, and promote angiogenesis and tissue regeneration. We proposed that CBD-VEGF could improve the performance of collagen in reconstruction of extensive urethral defects. Our results showed that collagen scaffolds modified with CBD-VEGF could promote urethral tissue regeneration and improve the function of the neo-urethra in a beagle extensive urethral defect model. Thus, modifying biomaterials with bioactive factors provides an alternative strategy for the production of suitable biomaterials for urethral reconstruction.

  14. Lead optimization of an acylhydrazone scaffold possessing antiviral activity against Lassa virus.

    Science.gov (United States)

    Burgeson, James R; Gharaibeh, Dima N; Moore, Amy L; Larson, Ryan A; Amberg, Sean M; Bolken, Tove' C; Hruby, Dennis E; Dai, Dongcheng

    2013-11-01

    Previously we reported the optimization of antiviral scaffolds containing benzimidazole and related heterocycles possessing activity against a variety of arenaviruses. These series of compounds were discovered through an HTS campaign of a 400,000 small molecule library using lentivirus-based pseudotypes incorporated with the Lassa virus envelope glycoprotein (LASV GP). This screening also uncovered an alternate series of very potent arenavirus inhibitors based upon an acylhydrazone scaffold. Subsequent SAR analysis of this chemical series involved various substitutions throughout the chemical framework along with assessment of the preferred stereochemistry. These studies led to an optimized analog (ST-161) possessing subnanomolar activity against LASV and submicromolar activity against a number of other viruses in the Arenaviridae family.

  15. Synthetic scaffold coating with adeno-associated virus encoding BMP2 to promote endogenous bone repair.

    Science.gov (United States)

    Dupont, Kenneth M; Boerckel, Joel D; Stevens, Hazel Y; Diab, Tamim; Kolambkar, Yash M; Takahata, Masahiko; Schwarz, Edward M; Guldberg, Robert E

    2012-03-01

    Biomaterial scaffolds functionalized to stimulate endogenous repair mechanisms via the incorporation of osteogenic cues offer a potential alternative to bone grafting for the treatment of large bone defects. We first quantified the ability of a self-complementary adeno-associated viral vector encoding bone morphogenetic protein 2 (scAAV2.5-BMP2) to enhance human stem cell osteogenic differentiation in vitro. In two-dimensional culture, scAAV2.5-BMP2-transduced human mesenchymal stem cells (hMSCs) displayed significant increases in BMP2 production and alkaline phosphatase activity compared with controls. hMSCs and human amniotic-fluid-derived stem cells (hAFS cells) seeded on scAAV2.5-BMP2-coated three-dimensional porous polymer Poly(ε-caprolactone) (PCL) scaffolds also displayed significant increases in BMP2 production compared with controls during 12 weeks of culture, although only hMSC-seeded scaffolds displayed significantly increased mineral formation. PCL scaffolds coated with scAAV2.5-BMP2 were implanted into critically sized immunocompromised rat femoral defects, both with or without pre-seeding of hMSCs, representing ex vivo and in vivo gene therapy treatments, respectively. After 12 weeks, defects treated with acellular scAAV2.5-BMP2-coated scaffolds displayed increased bony bridging and had significantly higher bone ingrowth and mechanical properties compared with controls, whereas defects treated with scAAV2.5-BMP2 scaffolds pre-seeded with hMSCs failed to display significant differences relative to controls. When pooled, defect treatment with scAAV2.5-BMP2-coated scaffolds, both with or without inclusion of pre-seeded hMSCs, led to significant increases in defect mineral formation at all time points and increased mechanical properties compared with controls. This study thus presents a novel acellular bone-graft-free endogenous repair therapy for orthotopic tissue-engineered bone regeneration.

  16. Flow perfusion culture of human mesenchymal stem cells on coralline hydroxyapatite scaffolds with various pore sizes.

    Science.gov (United States)

    Bjerre, Lea; Bünger, Cody; Baatrup, Anette; Kassem, Moustapha; Mygind, Tina

    2011-06-01

    Bone grafts are widely used in orthopaedic reconstructive surgery, but harvesting of autologous grafts is limited due to donor site complications. Bone tissue engineering is a possible alternative source for substitutes, and to date, mainly small scaffold sizes have been evaluated. The aim of this study was to obtain a clinically relevant substitute size using a direct perfusion culture system. Human bone marrowderived mesenchymal stem cells were seeded on coralline hydroxyapatite scaffolds with 200 μm or 500 μm pores, and resulting constructs were cultured in a perfusion bioreactor or in static culture for up to 21 days and analysed for cell distribution and osteogenic differentiation using histological stainings, alkaline phosphatase activity assay, and real-time RT-PCR on bone markers. We found that the number of cells was higher during static culture at most time points and that the final number of cells was higher in 500 μm constructs as compared with 200 μm constructs. Alkaline phosphatase enzyme activity assays and real time RT-PCR on seven osteogenic markers showed that differentiation occurred primarily and earlier in statically cultured constructs with 200 μm pores compared with 500 μm ones. Adhesion and proliferation of the cells was seen on both scaffold sizes, but the vitality and morphology of cells changed unfavorably during perfusion culture. In contrast to previous studies using spinner flask that show increased cellularity and osteogenic properties of cells when cultured dynamically, the perfusion culture in our study did not enhance the osteogenic properties of cell/scaffold constructs. The statically cultured constructs showed increasing cell numbers and abundant osteogenic differentiation probably because of weak initial cell adhesion due to the surface morphology of scaffolds. Our conclusion is that the specific scaffold surface microstructure and culturing system flow dynamics has a great impact on cell distribution and proliferation

  17. Micro-fabricated scaffolds lead to efficient remission of diabetes in mice.

    Science.gov (United States)

    Buitinga, Mijke; Assen, Frank; Hanegraaf, Maaike; Wieringa, Paul; Hilderink, Janneke; Moroni, Lorenzo; Truckenmüller, Roman; van Blitterswijk, Clemens; Römer, Gert-Willem; Carlotti, Françoise; de Koning, Eelco; Karperien, Marcel; van Apeldoorn, Aart

    2017-08-01

    Despite the clinical success of intrahepatic islet transplantation in treating type 1 diabetes, factors specific to this transplantation site hinder long-term insulin independence. The adoption of alternative, extravascular sites likely improve islet survival and function, but few locations are able to sufficiently confine islets in order to facilitate engraftment. This work describes a porous microwell scaffold with a well-defined pore size and spacing designed to guarantee islet retention at an extrahepatic transplantation site and facilitate islet revascularization. Three techniques to introduce pores were characterized: particulate leaching; solvent casting on pillared wafers; and laser drilling. Our criteria of a maximum pore diameter of 40 μm were best achieved via laser drilling. Transplantation studies in the epididymal fat of diabetic mice elucidated the potential of this porous scaffold platform to restore blood glucose levels and facilitate islet engraftment. Six out of eight mice reverted to stable normoglycemia with a mean time to remission of 6.2 ± 3.2 days, which was comparable to that of the gold standard of renal subcapsular islet grafts. In contrast, when islets were transplanted in the epididymal fat pad without a microwell scaffold, only two out of seven mice reverted to stable normoglycemia. Detailed histological evaluation four weeks after transplantation found a comparable vascular density in scaffold-seeded islets, renal subcapsular islets and native pancreatic islets. However, the vascularization pattern in scaffold-seeded islets was more inhomogeneous compared to native pancreatic islets with a higher vascular density in the outer shell of the islets compared to the inner core. We also observed a corresponding decrease in the beta-cell density in the islet core. Despite this, our data indicated that islets transplanted in the microwell scaffold platform were able to maintain a viable beta-cell population and restore glycemic control

  18. Aligned-Braided Nanofibrillar Scaffold with Endothelial Cells Enhances Arteriogenesis.

    Science.gov (United States)

    Nakayama, Karina H; Hong, Guosong; Lee, Jerry C; Patel, Jay; Edwards, Bryan; Zaitseva, Tatiana S; Paukshto, Michael V; Dai, Hongjie; Cooke, John P; Woo, Y Joseph; Huang, Ngan F

    2015-07-28

    The objective of this study was to enhance the angiogenic capacity of endothelial cells (ECs) using nanoscale signaling cues from aligned nanofibrillar scaffolds in the setting of tissue ischemia. Thread-like nanofibrillar scaffolds with porous structure were fabricated from aligned-braided membranes generated under shear from liquid crystal collagen solution. Human ECs showed greater outgrowth from aligned scaffolds than from nonpatterned scaffolds. Integrin α1 was in part responsible for the enhanced cellular outgrowth on aligned nanofibrillar scaffolds, as the effect was abrogated by integrin α1 inhibition. To test the efficacy of EC-seeded aligned nanofibrillar scaffolds in improving neovascularization in vivo, the ischemic limbs of mice were treated with EC-seeded aligned nanofibrillar scaffold; EC-seeded nonpatterned scaffold; ECs in saline; aligned nanofibrillar scaffold alone; or no treatment. After 14 days, laser Doppler blood spectroscopy demonstrated significant improvement in blood perfusion recovery when treated with EC-seeded aligned nanofibrillar scaffolds, in comparison to ECs in saline or no treatment. In ischemic hindlimbs treated with scaffolds seeded with human ECs derived from induced pluripotent stem cells (iPSC-ECs), single-walled carbon nanotube (SWNT) fluorophores were systemically delivered to quantify microvascular density after 28 days. Near infrared-II (NIR-II, 1000-1700 nm) imaging of SWNT fluorophores demonstrated that iPSC-EC-seeded aligned scaffolds group showed significantly higher microvascular density than the saline or cells groups. These data suggest that treatment with EC-seeded aligned nanofibrillar scaffolds improved blood perfusion and arteriogenesis, when compared to treatment with cells alone or scaffold alone, and have important implications in the design of therapeutic cell delivery strategies.

  19. SCAFFOLDING DALAM MICROTEACHING KIMIA BERBASIS PEMBELAJARAN LANGSUNG DAN SIKLUS BELAJAR

    Directory of Open Access Journals (Sweden)

    Abdullatif Nusu

    2014-09-01

    Full Text Available Abstract: Scaffolding in Chemistry Microteaching Utilizing  Direct Instruction and Learning Cycle. This study concerns developing students’ competence in conducting microteaching in chemistry, especially in preparing lesson plans using direct instruction and learning cycle and in implementing the lesson plans in peer teaching. The microteaching skills of 26 students are enhanced using scaffolding, implemented gradually and integratedly. The scaffolding comprises three stages: orientation of the task, revising the lesson plan, and carrying out peer teaching. Scaffolding is found to enable the students to develop lesson plans and to realize the lesson plans in peer teaching, as can be seen from their scores on the two aspects. In addi­tion, the students respond positively to the use of scaffolding in microteaching. Keywords: scaffolding, lesson plan writing, peer teaching, chemistry microteaching Abstrak: Scaffolding dalam Microteaching Kimia Berbasis Pembelajaran Langsung dan Siklus Be­lajar. Penelitian tentang kemampuan mahasiswa dalam melaksanakan microteaching kimia, khususnya dalam menulis rencana pelaksanaan pembelajaran berbasis pembelajaran langsung dan siklus belajar serta menerapkannya dalam peer teaching, telah dilakukan terhadap 26 mahasiswa Program Studi Pendidikan Kimia Universitas Haluoleo di Kendari, Sulawesi Tenggara. Kemampuan melaksanakan microteaching mahasiswa ditingkatkan dengan menggunakan scaffolding yang dilakukan secara bertahap dan terpadu. Scaffolding tersebut terdiri dari tiga tahap yaitu orientasi tugas dan memodelkan cara menggunakan sum­ber scaffolding, revisi Rencana Pelaksanaan Pembelajaran (RPP melalui artikulasi dan refleksi untuk menghasilkan RPP kelompok, dan melaksanakan peer teaching. Keberhasilan scaffolding dalam micro­teaching kimia ditunjukkan dengan tercapainya skor penulisan RPP dan skor pelaksanaan peer teaching yang memenuhi kriteria ketuntasan minimal. Hasil penelitian menunjukkan bahwa

  20. Rapid prototyped porous nickel–titanium scaffolds as bone substitutes

    Directory of Open Access Journals (Sweden)

    Waldemar Hoffmann

    2014-06-01

    Full Text Available While calcium phosphate–based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel–titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel–titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel–titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel–titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel–titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel–titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold’s pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel–titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used

  1. Histological assessment of regenerative endodontic treatment in animal studies with different scaffolds: A systematic review.

    Science.gov (United States)

    Altaii, Milad; Richards, Lindsay; Rossi-Fedele, Giampiero

    2017-08-01

    The concept of regenerative endodontic procedures remains controversial. The aim of this study was to evaluate the histology of the tissues formed in immature animal teeth with necrotic and infected pulps after attempted endodontic regeneration procedures using different scaffolds. A systematic electronic literature search was performed in PubMed, Web of Science, Scopus, EMBASE, DOSS, and Cochrane Library databases. The terms used were a combination of the following: "immature permanent necrotic tooth or teeth" or "open apex or apices" and "regeneration or revitalization or revascularization" and "histology." The inclusion criteria comprised animal studies with histological examination following regenerative endodontics in immature necrotic-infected permanent teeth. From 123 screened studies, 13 met the inclusion criteria. Formation of dentin-like tissue on the dentinal walls was reported in only 4% of teeth treated with blood clot scaffold and 2% treated with blood clot with additional materials. Cementum-like hard tissue was found in 64% of teeth with blood clot, 80% treated with blood clot with additional materials, 50% treated with alternative scaffolds, and 5% that were left empty. Bone-like tissue was reported in 10% of teeth treated with blood clot, 2% treated with blood clot with additional materials, and 4% treated with alternative scaffolds. The tissues in the canal space were found to be connective tissue with infiltration of fibroblast-like cells and blood vessels. Forty-six percent of the studies reported formation of periodontal ligament-like tissues. None of the regeneration protocols resulted in the predictable formation of a true pulp-dentin complex. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Use of Interim Scaffolding and Neotissue Development to Produce a Scaffold-Free Living Hyaline Cartilage Graft.

    Science.gov (United States)

    Lau, Ting Ting; Leong, Wenyan; Peck, Yvonne; Su, Kai; Wang, Dong-An

    2015-01-01

    The fabrication of three-dimensional (3D) constructs relies heavily on the use of biomaterial-based scaffolds. These are required as mechanical supports as well as to translate two-dimensional cultures to 3D cultures for clinical applications. Regardless of the choice of scaffold, timely degradation of scaffolds is difficult to achieve and undegraded scaffold material can lead to interference in further tissue development or morphogenesis. In cartilage tissue engineering, hydrogel is the highly preferred scaffold material as it shares many similar characteristics with native cartilaginous matrix. Hence, we employed gelatin microspheres as porogens to create a microcavitary alginate hydrogel as an interim scaffold to facilitate initial chondrocyte 3D culture and to establish a final scaffold-free living hyaline cartilaginous graft (LhCG) for cartilage tissue engineering.

  3. Percutaneous left atrial appendage occlusion – treatment outcomes and 6 months of follow-up – a single-center experience

    Science.gov (United States)

    Karczewski, Michał; Skowronek, Radomir; Burysz, Marian; Fischer, Marcin; Anisimowicz, Lech; Demkow, Marcin; Konka, Marek; Ogorzeja, Wojciech

    2016-01-01

    Aim To present the results of treatment and evaluate 6 months of follow-up in a group of patients with non-valvular atrial fibrillation, who underwent the procedure of percutaneous left atrial appendage occlusion (PLAAO). Material and methods Percutaneous left atrial appendage occlusion was performed in 34 patients with non-valvular atrial fibrillation and contraindications for oral anticoagulation therapy. The risk of thromboembolic and bleeding complications was determined based on the CHA2DS2VASc and HAS-BLED scales. The Amplatzer Amulet system from St. Jude Medical was used. On the first postoperative day, all patients were started on double antiplatelet therapy with 75 mg/day of acetylsalicylic acid (ASA) and 75 mg/day of clopidogrel (CLO). On the 30th postoperative day, the efficacy of the antiplatelet therapy was assessed with impedance aggregometry using a Multiplate analyzer (Roche). Echocardiographic examinations were performed intraoperatively and on the first postoperative day; subsequently, follow-up examinations were conducted 1 and 6 months after the implantation. Results In all patients, proper occluder position was observed throughout the follow-up. No leakage or thrombi around the implants were found. No strokes or bleeding complications associated with the antiplatelet therapy were observed. Multiplate assessment of platelet activity was conducted in 20 out of 34 patients. The efficacy of ASA treatment was demonstrated in all patients; no response to clopidogrel treatment was observed in 5 out of 20 patients. One patient suffered from cardiac tamponade, which required the performance of full sternotomy. Local complications (hematomas of the inguinal region) were observed in 3 patients. One of the patients died for reasons unrelated to the procedure. Conclusions Percutaneous left atrial appendage occlusion is an effective procedure in patients with non-valvular atrial fibrillation and contraindications for chronic anticoagulation therapy. Further

  4. The Value of 3D Printing Models of Left Atrial Appendage Using Real-Time 3D Transesophageal Echocardiographic Data in Left Atrial Appendage Occlusion: Applications toward an Era of Truly Personalized Medicine.

    Science.gov (United States)

    Liu, Peng; Liu, Rijing; Zhang, Yan; Liu, Yingfeng; Tang, Xiaoming; Cheng, Yanzhen

    2016-01-01

    The objective of this study was to assess the clinical feasibility of generating 3D printing models of left atrial appendage (LAA) using real-time 3D transesophageal echocardiogram (TEE) data for preoperative reference of LAA occlusion. Percutaneous LAA occlusion can effectively prevent patients with atrial fibrillation from stroke. However, the anatomical structure of LAA is so complicated that adequate information of its structure is essential for successful LAA occlusion. Emerging 3D printing technology has the demonstrated potential to structure more accurately than conventional imaging modalities by creating tangible patient-specific models. Typically, 3D printing data sets are acquired from CT and MRI, which may involve intravenous contrast, sedation, and ionizing radiation. It has been reported that 3D models of LAA were successfully created by the data acquired from CT. However, 3D printing of the LAA using real-time 3D TEE data has not yet been explored. Acquisition of 3D transesophageal echocardiographic data from 8 patients with atrial fibrillation was performed using the Philips EPIQ7 ultrasound system. Raw echocardiographic image data were opened in Philips QLAB and converted to 'Cartesian DICOM' format and imported into Mimics® software to create 3D models of LAA, which were printed using a rubber-like material. The printed 3D models were then used for preoperative reference and procedural simulation in LAA occlusion. We successfully printed LAAs of 8 patients. Each LAA costs approximately CNY 800-1,000 and the total process takes 16-17 h. Seven of the 8 Watchman devices predicted by preprocedural 2D TEE images were of the same sizes as those placed in the real operation. Interestingly, 3D printing models were highly reflective of the shape and size of LAAs, and all device sizes predicted by the 3D printing model were fully consistent with those placed in the real operation. Also, the 3D printed model could predict operating difficulty and the

  5. Effect of copper-doped silicate 13-93 bioactive glass scaffolds on the response of MC3T3-E1 cells in vitro and on bone regeneration and angiogenesis in rat calvarial defects in vivo.

    Science.gov (United States)

    Lin, Yinan; Xiao, Wei; Bal, B Sonny; Rahaman, Mohamed N

    2016-10-01

    The release of inorganic ions from biomaterials could provide an alternative approach to the use of growth factors for improving tissue healing. In the present study, the release of copper (Cu) ions from bioactive silicate (13-93) glass scaffolds on the response of cells in vitro and on bone regeneration and angiogenesis in vivo was studied. Scaffolds doped with varying concentrations of Cu (0-2.0wt.% CuO) were created with a grid-like microstructure by robotic deposition. When immersed in simulated body fluid in vitro, the Cu-doped scaffolds released Cu ions into the medium in a dose-dependent manner and converted partially to hydroxyapatite. The proliferation and alkaline phosphatase activity of pre-osteoblastic MC3T3-E1 cells cultured on the scaffolds were not affected by 0.4 and 0.8wt.% CuO in the glass but they were significantly reduced by 2.0wt.% CuO. The percent new bone that infiltrated the scaffolds implanted for 6weeks in rat calvarial defects (46±8%) was not significantly affected by 0.4 or 0.8wt.% CuO in the glass whereas it was significantly inhibited (0.8±0.7%) in the scaffolds doped with 2.0wt.% CuO. The area of new blood vessels in the fibrous tissue that infiltrated the scaffolds increased with CuO content of the glass and was significantly higher for the scaffolds doped with 2.0wt.% CuO. Loading the scaffolds with bone morphogenetic protein-2 (1μg/defect) significantly enhanced bone infiltration and reduced fibrous tissue in the scaffolds. These results showed that doping the 13-93 glass scaffolds with up to 0.8wt.% CuO did not affect their biocompatibility whereas 2.0wt.% CuO was toxic to cells and detrimental to bone regeneration.

  6. Percutaneous closure of the left atrial appendage for prevention of thromboembolism in atrial fibrillation for patients with contraindication to or failure of oral anticoagulation: a single-center experience.

    Science.gov (United States)

    Faustino, Ana; Paiva, Luís; Providência, Rui; Trigo, Joana; Botelho, Ana; Costa, Marco; Leitão-Marques, António

    2013-06-01

    In non-valvular atrial fibrillation 90% of thrombi originate in the left atrial appendage (LAA). Percutaneous LAA closure has been shown to be non-inferior to warfarin for prevention of thromboembolism. To evaluate the initial experience of a single center in percutaneous LAA closure in patients with high thromboembolic risk and in whom oral anticoagulation was impractical or contraindicated or had failed. Patients with non-valvular atrial fibrillation and CHADS2 score ≥2 in whom oral anticoagulation was impractical or contraindicated or had failed underwent percutaneous LAA closure according to the standard technique. After the procedure, dual antiplatelet therapy was maintained for one month, followed by single antiplatelet therapy indefinitely. Patients were followed by clinical assessment and transthoracic and transesophageal echocardiography. The procedure was performed in 22 of the 23 selected patients (95.7%), mean age 70±9 years, CHADS2 score 3.2±0.9 and CHA2DS2-VASC score 4.7±1.4. Intraprocedural device replacement was necessary only in the first patient, due to oversizing. The following periprocedural complications were observed: one femoral pseudoaneurysm, three femoral hematomas and two minor oropharyngeal bleeds, resolved by local hemostatic measures. During a 12±8 month follow-up a mild peri-device flow and a thrombus adhering to the device, resolved under with enoxaparin therapy, were identified. The rate of transient ischemic attack (TIA)/stroke was lower than expected according to the CHADS2 score (0 vs. 6.7±2.2%). In our initial experience, this procedure proved to be a feasible, safe and effective alternative for atrial fibrillation patients in whom oral anticoagulation is not an option. Only relatively minor complications were observed, with a lower than expected TIA/stroke rate. Copyright © 2012 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  7. Looking for an Alternative.

    Science.gov (United States)

    Kennedy, Jack

    1999-01-01

    Argues that high school newspapers might do well to create stronger ties with alternative weeklies. Discusses issues of niche marketing, alternative content, and alternative presentation. Notes that high school papers could learn a lot from alternative newspapers. (SR)

  8. Membrane-mediated interaction between strongly anisotropic protein scaffolds.

    Directory of Open Access Journals (Sweden)

    Yonatan Schweitzer

    2015-02-01

    Full Text Available Specialized proteins serve as scaffolds sculpting strongly curved membranes of intracellular organelles. Effective membrane shaping requires segregation of these proteins into domains and is, therefore, critically dependent on the protein-protein interaction. Interactions mediated by membrane elastic deformations have been extensively analyzed within approximations of large inter-protein distances, small extents of the protein-mediated membrane bending and small deviations of the protein shapes from isotropic spherical segments. At the same time, important classes of the realistic membrane-shaping proteins have strongly elongated shapes with large and highly anisotropic curvature. Here we investigated, computationally, the membrane mediated interaction between proteins or protein oligomers representing membrane scaffolds with strongly anisotropic curvature, and addressed, quantitatively, a specific case of the scaffold geometrical parameters characterizing BAR domains, which are crucial for membrane shaping in endocytosis. In addition to the previously analyzed contributions to the interaction, we considered a repulsive force stemming from the entropy of the scaffold orientation. We computed this interaction to be of the same order of magnitude as the well-known attractive force related to the entropy of membrane undulations. We demonstrated the scaffold shape anisotropy to cause a mutual aligning of the scaffolds and to generate a strong attractive interaction bringing the scaffolds close to each other to equilibrium distances much smaller than the scaffold size. We computed the energy of interaction between scaffolds of a realistic geometry to constitute tens of kBT, which guarantees a robust segregation of the scaffolds into domains.

  9. Fabrication and characterization of multiscale electrospun scaffolds for cartilage regeneration.

    Science.gov (United States)

    Levorson, Erica J; Raman Sreerekha, Perumcherry; Chennazhi, Krishna Prasad; Kasper, F Kurtis; Nair, Shantikumar V; Mikos, Antonios G

    2013-02-01

    Recently, scaffolds for tissue regeneration purposes have been observed to utilize nanoscale features in an effort to reap the cellular benefits of scaffold features resembling extracellular matrix (ECM) components. However, one complication surrounding electrospun nanofibers is limited cellular infiltration. One method to ameliorate this negative effect is by incorporating nanofibers into microfibrous scaffolds. This study shows that it is feasible to fabricate electrospun scaffolds containing two differently scaled fibers interspersed evenly throughout the entire construct as well as scaffolds containing fibers composed of two discrete materials, specifically fibrin and poly(ε-caprolactone). In order to accomplish this, multiscale fibrous scaffolds of different compositions were generated using a dual extrusion electrospinning setup with a rotating mandrel. These scaffolds were then characterized for fiber diameter, porosity and pore size and seeded with human mesenchymal stem cells to assess the influence of scaffold architecture and composition on cellular responses as determined by cellularity, histology and glycosaminoglycan (GAG) content. Analysis revealed that nanofibers within a microfiber mesh function to maintain scaffold cellularity under serum-free conditions as well as aid the deposition of GAGs. This supports the hypothesis that scaffolds with constituents more closely resembling native ECM components may be beneficial for cartilage regeneration.

  10. DNA Origami with Double Stranded DNA as a Unified Scaffold

    Science.gov (United States)

    Yang, Yang; Han, Dongran; Nangreave, Jeanette; Liu, Yan; Yan, Hao

    2013-01-01

    Scaffolded DNA origami is a widely used technology for self-assembling precisely structured nanoscale objects that contain a large number of addressable features. Typical scaffolds are long, single strands of DNA (ssDNA) that are folded into distinct shapes through the action of many, short ssDNA staples that are complementary to several different domains of the scaffold. However, sources of long single stranded DNA are scarce, limiting the size and complexity of structures that can be assembled. Here we demonstrated that dsDNA scaffolds can be directly used to fabricate integrated DNA origami structures that incorporate both of the constituent ssDNA molecules. Two basic principles were employed in the design of scaffold folding paths – folding path asymmetry and periodic convergence of the two ssDNA scaffold strands. Asymmetry in the folding path minimizes unwanted complementarity between staples, and incorporating an offset between the folding paths of each ssDNA scaffold strand reduces the number of times that complementary portions of the strands are brought into close proximity with one another, both of which decrease the likelihood of dsDNA scaffold recovery. Meanwhile, the folding paths of the two ssDNA scaffold strands were designed to periodically converge to promote the assembly of a single, unified structure rather than two individual ones. Our results reveal that this basic strategy can be used to reliably assemble integrated DNA nanostructures from dsDNA scaffolds. PMID:22830653

  11. Image-based characterization of foamed polymeric tissue scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Mather, Melissa L; Morgan, Stephen P; Crowe, John A [School of Electrical and Electronic Engineering, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); White, Lisa J; Shakesheff, Kevin M [School of Pharmacy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Tai, Hongyun; Howdle, Steven M [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Kockenberger, Walter [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)], E-mail: john.crowe@nottingham.ac.uk

    2008-03-01

    Tissue scaffolds are integral to many regenerative medicine therapies, providing suitable environments for tissue regeneration. In order to assess their suitability, methods to routinely and reproducibly characterize scaffolds are needed. Scaffold structures are typically complex, and thus their characterization is far from trivial. The work presented in this paper is centred on the application of the principles of scaffold characterization outlined in guidelines developed by ASTM International. Specifically, this work demonstrates the capabilities of different imaging modalities and analysis techniques used to characterize scaffolds fabricated from poly(lactic-co-glycolic acid) using supercritical carbon dioxide. Three structurally different scaffolds were used. The scaffolds were imaged using: scanning electron microscopy, micro x-ray computed tomography, magnetic resonance imaging and terahertz pulsed imaging. In each case two-dimensional images were obtained from which scaffold properties were determined using image processing. The findings of this work highlight how the chosen imaging modality and image-processing technique can influence the results of scaffold characterization. It is concluded that in order to obtain useful results from image-based scaffold characterization, an imaging methodology providing sufficient contrast and resolution must be used along with robust image segmentation methods to allow intercomparison of results.

  12. Hemocompatible surface of electrospun nanofibrous scaffolds by ATRP modification.

    Science.gov (United States)

    Yuan, Wenjie; Feng, Yakai; Wang, Heyun; Yang, Dazhi; An, Bo; Zhang, Wencheng; Khan, Musammir; Guo, Jintang

    2013-10-01

    The electrospun scaffolds are potential application in vascular tissue engineering since they can mimic the nano-sized dimension of natural extracellular matrix (ECM). We prepared a fibrous scaffold from polycarbonateurethane (PCU) by electrospinning technology. In order to improve the hydrophilicity and hemocompatibility of the fibrous scaffold, poly(ethylene glycol) methacrylate (PEGMA) was grafted onto the fiber surface by surface-initiated atom transfer radical polymerization (SI-ATRP) method. Although SI-ATRP has been developed and used for surface modification for many years, there are only few studies about the modification of electrospun fiber by this method. The modified fibrous scaffolds were characterized by SEM, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The scaffold morphology showed no significant difference when PEGMA was grafted onto the scaffold surface. Based on the water contact angle measurement, the surface hydrophilicity of the scaffold surface was improved significantly after grafting hydrophilic PEGMA (P=0.0012). The modified surface showed effective resistance for platelet adhesion compared with the unmodified surface. Activated partial thromboplastin time (APTT) of the PCU-g-PEGMA scaffold was much longer than that of the unmodified PCU scaffold. The cyto-compatibility of electrospun nanofibrous scaffolds was tested by human umbilical vein endothelial cells (HUVECs). The images of 7-day cultured cells on the scaffold surface were observed by SEM. The modified scaffolds showed high tendency to induce cell adhesion. Moreover, the cells reached out pseudopodia along the fibrous direction and formed a continuous monolayer. Hemolysis test showed that the grafted chains of PEGMA reduced blood coagulation. These results indicated that the modified electrospun nanofibrous scaffolds were potential application as artificial blood vessels.

  13. Hydroxyapatite reinforced collagen scaffolds with improved architecture and mechanical properties.

    Science.gov (United States)

    Kane, Robert J; Weiss-Bilka, Holly E; Meagher, Matthew J; Liu, Yongxing; Gargac, Joshua A; Niebur, Glen L; Wagner, Diane R; Roeder, Ryan K

    2015-04-01

    Hydroxyapatite (HA) reinforced collagen scaffolds have shown promise for synthetic bone graft substitutes and tissue engineering scaffolds. Freeze-dried HA-collagen scaffolds are readily fabricated and have exhibited osteogenicity in vivo, but are limited by an inherent scaffold architecture that results in a relatively small pore size and weak mechanical properties. In order to overcome these limitations, HA-collagen scaffolds were prepared by compression molding HA reinforcements and paraffin microspheres within a suspension of concentrated collagen fibrils (∼ 180 mg/mL), cross-linking the collagen matrix, and leaching the paraffin porogen. HA-collagen scaffolds exhibited an architecture with high porosity (85-90%), interconnected pores ∼ 300-400 μm in size, and struts ∼ 3-100 μm in thickness containing 0-80 vol% HA whisker or powder reinforcements. HA reinforcement enabled a compressive modulus of up to ∼ 1 MPa, which was an order of magnitude greater than unreinforced collagen scaffolds. The compressive modulus was also at least one order of magnitude greater than comparable freeze-dried HA-collagen scaffolds and two orders of magnitude greater than absorbable collagen sponges used clinically. Moreover, scaffolds reinforced with up to 60 vol% HA exhibited fully recoverable elastic deformation upon loading to 50% compressive strain for at least 100,000 cycles. Thus, the scaffold mechanical properties were well-suited for surgical handling, fixation, and bearing osteogenic loads during bone regeneration. The scaffold architecture, permeability, and composition were shown to be conducive to the infiltration and differentiation of adipose-derive stromal cells in vitro. Acellular scaffolds were demonstrated to induce angiogenesis and osteogenesis after subcutaneous ectopic implantation by recruiting endogenous cell populations, suggesting that the scaffolds were osteoinductive.

  14. Construction of collagen II/hyaluronate/chondroitin-6-sulfate tri-copolymer scaffold for nucleus pulposus tissue engineering and preliminary analysis of its physico-chemical properties and biocompatibility.

    Science.gov (United States)

    Li, Chang-Qing; Huang, Bo; Luo, Gang; Zhang, Chuan-Zhi; Zhuang, Ying; Zhou, Yue

    2010-02-01

    To construct a novel scaffold for nucleus pulposus (NP) tissue engineering, The porous type II collagen (CII)/hyaluronate (HyA)-chondroitin-6-sulfate (6-CS) scaffold was prepared using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) cross-linking system. The physico-chemical properties and biocompatibility of CII/HyA-CS scaffolds were evaluated. The results suggested CII/HyA-CS scaffolds have a highly porous structure (porosity: 94.8 +/- 1.5%), high water-binding capacity (79.2 +/- 2.8%) and significantly improved mechanical stability by EDC/NHS crosslinking (denaturation temperature: 74.6 +/- 1.8 and 58.1 +/- 2.6 degrees C, respectively, for the crosslinked scaffolds and the non-crosslinked; collagenase degradation rate: 39.5 +/- 3.4 and 63.5 +/- 2.0%, respectively, for the crosslinked scaffolds and the non-crosslinked). The CII/HyA-CS scaffolds also showed satisfactory cytocompatibility and histocompatibility as well as low immunogenicity. These results indicate CII/HyA-CS scaffolds may be an alternative material for NP tissue engineering due to the similarity of its composition and physico-chemical properties to those of the extracellular matrices (ECM) of native NP.

  15. Fabrication and Characterization of Spongy Denuded Amniotic Membrane Based Scaffold for Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Ehsan Taghiabadi

    2015-01-01

    Full Text Available Objective: As a biological tissue material, amniotic membrane (AM has low immunogenicity and to date has been widely adopted in clinical practice. However, some features such as low biomechanical consistency and rapid biodegradation is limited the application of AM. Therefore, in this study, we fabricated a novel three-dimensional (3D spongy scaffold made of the extracellular matrix (ECM of denuded AM. Due to their unique characteristics which are similar to the skin, these scaffolds can be considered as an alternative option in skin tissue engineering. Materials and Methods: In this experimental study, cellular components of human amniotic membrane (HAM were removed with 0.03% (w/v sodium dodecyl sulphate (SDS. Quantitative analysis was performed to determine levels of Glycosaminoglycans (GAGs, collagen, and deoxyribonucleic acid (DNA. To increase the low efficiency and purity of the ECM component, especially collagen and GAG, we applied an acid solubilization procedure hydrochloridric acid (HCl 0.1 M with pepsin (1 mg/ml. In the present experiment 1-ethyl-3-(3-dimethyl aminopropyl carbodiimide hydrochloride (EDC/N-hydroxysuccinimide (NHS cross linker agent was used to improve the mechanical properties of 3D lyophilized AM scaffold. The spongy 3D AM scaffolds were specified, by scanning electron microscopy, hematoxylin and eosin (H&E staining, a swelling test, and mechanical strength and in vitro biodegradation tests. Human fetal fibroblast culture systems were used to establish that the scafolds were cytocompatible. Results: Histological analysis of treated human AM showed impressive removal of cellular components. DNA content was diminished after treatment (39 ± 4.06 μg/ml vs. 341 ± 29.60 μg/ml. Differences were observed between cellular and denude AM in matrix collagen (478 ± 18.06 μg/mg vs. 361 ± 27.47 μg/mg.With the optimum concentration of 1 mM NHS/EDC ratio1:4, chemical cross-linker agent could significantly increase the

  16. Quantitative Evaluation of the Substantially Variable Morphology and Function of the Left Atrial Appendage and Its Relation with Adjacent Structures.

    Directory of Open Access Journals (Sweden)

    Cai-Ying Li

    Full Text Available To investigate quantitatively the morphology, anatomy and function of the left atrial appendage (LAA and its relation with