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Sample records for post-transcriptional bmp2 switch

  1. Role of a redox-based methylation switch in mRNA life cycle ( pre- & post- transcriptional maturation and protein turnover : Implications in neurological disorders

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    MALAV SUCHIN TRIVEDI

    2012-06-01

    Full Text Available Homeostatic synaptic scaling in response to neuronal stimulus or activation, as well as due to changes in cellular niche, is an important phenomenon for memory consolidation, retrieval, and other similar cognitive functions. Neurological disorders and cognitive disabilities in autism, Rett syndrome, schizophrenia, dementia etc., are strongly correlated to alterations in protein expression (both synaptic and cytoplasmic. This correlation suggests that efficient temporal regulation of synaptic protein expression is important for synaptic plasticity. In addition, equilibrium between mRNA processing, protein translation and protein turnover is a critical sensor/trigger for recording synaptic information, normal cognition and behavior. Thus a regulatory switch, controlling the lifespan, maturation and processing of mRNA, might influence cognition and adaptive behavior. Here, we propose a two part novel hypothesis that methylation might act as this suggested coordinating switch to critically regulate mRNA maturation at 1.The pre-transcription level, by regulating precursor-RNA (pre-RNA processing into mRNA, via other non-coding RNAs and their influence on splicing phenomenon, and 2. the post-transcription level by modulating the regulatory functions of ribonucleoproteins (RNP and RNA binding proteins (RNABP in mRNA translation, dendritic translocation as well as protein synthesis and synaptic turnover. DNA methylation changes are well recognized and highly correlated to gene expression levels as well as, learning and memory; however, RNA methylation changes are recently characterized and yet their functional implications are not established. This review article provides some insight on the intriguing consequences of changes in methylation levels on mRNA life-cycle. We also suggest that, since methylation is under the control of glutathione antioxidant levels, the redox status of neurons might be the central regulatory switch for methylation

  2. The post-transcriptional operon

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    Tenenbaum, Scott A.; Christiansen, Jan; Nielsen, Henrik

    2011-01-01

    model (PTO) is used to describe data from an assortment of methods (e.g. RIP-Chip, CLIP-Chip, miRNA profiling, ribosome profiling) that globally address the functionality of mRNA. Several examples of post-transcriptional operons have been documented in the literature and demonstrate the usefulness...... of the model in identifying new participants in cellular pathways as well as in deepening our understanding of cellular responses....

  3. Histone deacetylases control neurogenesis in embryonic brain by inhibition of BMP2/4 signaling.

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    Maya Shakèd

    Full Text Available BACKGROUND: Histone-modifying enzymes are essential for a wide variety of cellular processes dependent upon changes in gene expression. Histone deacetylases (HDACs lead to the compaction of chromatin and subsequent silencing of gene transcription, and they have recently been implicated in a diversity of functions and dysfunctions in the postnatal and adult brain including ocular dominance plasticity, memory consolidation, drug addiction, and depression. Here we investigate the role of HDACs in the generation of neurons and astrocytes in the embryonic brain. PRINCIPAL FINDINGS: As a variety of HDACs are expressed in differentiating neural progenitor cells, we have taken a pharmacological approach to inhibit multiple family members. Inhibition of class I and II HDACs in developing mouse embryos with trichostatin A resulted in a dramatic reduction in neurogenesis in the ganglionic eminences and a modest increase in neurogenesis in the cortex. An identical effect was observed upon pharmacological inhibition of HDACs in in vitro-differentiating neural precursors derived from the same brain regions. A reduction in neurogenesis in ganglionic eminence-derived neural precursors was accompanied by an increase in the production of immature astrocytes. We show that HDACs control neurogenesis by inhibition of the bone morphogenetic protein BMP2/4 signaling pathway in radial glial cells. HDACs function at the transcriptional level by inhibiting and promoting, respectively, the expression of Bmp2 and Smad7, an intracellular inhibitor of BMP signaling. Inhibition of the BMP2/4 signaling pathway restored normal levels of neurogenesis and astrogliogenesis to both ganglionic eminence- and cortex-derived cultures in which HDACs were inhibited. CONCLUSIONS: Our results demonstrate a transcriptionally-based regulation of BMP2/4 signaling by HDACs both in vivo and in vitro that is critical for neurogenesis in the ganglionic eminences and that modulates cortical

  4. Calcium phosphate implants coatings as carriers for BMP-2

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    Liu, Y.; He, J.F.; Hunziker, E.B.

    2009-01-01

    The osteoconductivity of dental implants can be improved by coating them with a layer of calcium phosphate (CaP), which can be rendered osteoinductive by functionalizing it with an osteogenic agent, such as bone morphogenetic protein 2 (BMP-2). In the present study, we wished to compare the

  5. Post-transcriptional bursting in genes regulated by small RNA molecules

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    Rodrigo, Guillermo

    2018-03-01

    Gene expression programs in living cells are highly dynamic due to spatiotemporal molecular signaling and inherent biochemical stochasticity. Here we study a mechanism based on molecule-to-molecule variability at the RNA level for the generation of bursts of protein production, which can lead to heterogeneity in a cell population. We develop a mathematical framework to show numerically and analytically that genes regulated post transcriptionally by small RNA molecules can exhibit such bursts due to different states of translation activity (on or off), mostly revealed in a regime of few molecules. We exploit this framework to compare transcriptional and post-transcriptional bursting and also to illustrate how to tune the resulting protein distribution with additional post-transcriptional regulations. Moreover, because RNA-RNA interactions are predictable with an energy model, we define the kinetic constants of on-off switching as functions of the two characteristic free-energy differences of the system, activation and formation, with a nonequilibrium scheme. Overall, post-transcriptional bursting represents a distinctive principle linking gene regulation to gene expression noise, which highlights the importance of the RNA layer beyond the simple information transfer paradigm and significantly contributes to the understanding of the intracellular processes from a first-principles perspective.

  6. Post-transcriptional regulation of ribosome biogenesis in yeast

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    Isabelle C. Kos-Braun

    2017-05-01

    Full Text Available Most microorganisms are exposed to the constantly and often rapidly changing environment. As such they evolved mechanisms to balance their metabolism and energy expenditure with the resources available to them. When resources become scarce or conditions turn out to be unfavourable for growth, cells reduce their metabolism and energy usage to survive. One of the major energy consuming processes in the cell is ribosome biogenesis. Unsurprisingly, cells encountering adverse conditions immediately shut down production of new ribosomes. It is well established that nutrient depletion leads to a rapid repression of transcription of the genes encoding ribosomal proteins, ribosome biogenesis factors as well as ribosomal RNA (rRNA. However, if pre-rRNA processing and ribosome assembly are regulated post-transcriptionally remains largely unclear. We have recently uncovered that the yeast Saccharomyces cerevisiae rapidly switches between two alternative pre-rRNA processing pathways depending on the environmental conditions. Our findings reveal a new level of complexity in the regulation of ribosome biogenesis.

  7. Bone regeneration by implantation of adipose-derived stromal cells expressing BMP-2

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    Li Huiwu; Dai Kerong; Tang Tingting; Zhang Xiaoling; Yan Mengning; Lou Jueren

    2007-01-01

    In this study, we reported that the adipose-derived stromal cells (ADSCs) genetically modified by bone morphogenetic protein 2 (BMP-2) healed critical-sized canine ulnar bone defects. First, the osteogenic and adipogenic differentiation potential of the ADSCs derived from canine adipose tissue were demonstrated. And then the cells were modified by the BMP-2 gene and the expression and bone-induction ability of BMP-2 were identified. Finally, the cells modified by BMP-2 gene were applied to a β-tricalcium phosphate (TCP) carrier and implanted into ulnar bone defects in the canine model. After 16 weeks, radiographic, histological, and histomorphometry analysis showed that ADSCs modified by BMP-2 gene produced a significant increase of newly formed bone area and healed or partly healed all of the bone defects. We conclude that ADSCs modified by the BMP-2 gene can enhance the repair of critical-sized bone defects in large animals

  8. Dexamethasone, BMP-2, and 1,25-dihydroxyvitamin D enhance a more differentiated osteoblast phenotype

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    Jørgensen, Niklas Rye; Henriksen, Z; Sørensen, O H

    2004-01-01

    . Osteoblast phenotypes were induced by either dexamethasone (Dex) or bone morphogenetic protein-2 (BMP-2). Bone marrow was obtained from biopsies at the posterior iliac spine. Cells were isolated by gradient centrifugation and grown to confluence. Cells were treated with 1 nM 1,25-dihydroxyvitamin D (vitamin...... activity was increased by Dex, but not by BMP-2 treatment. P1NP production was decreased after Dex treatment, while BMP-2 had no effect on P1NP levels. Osteocalcin production was low in cultures not stimulated with vitamin D. Dex or BMP-2 treatment alone did not affect the basic osteocalcin levels......, but in combination with vitamin D, BMP-2 increased the osteocalcin production, while Dex treatment completely suppressed osteocalcin production. Further, PTH-induced cAMP production was greatly enhanced by Dex treatment, whereas BMP-2 did not affect cAMP production. Finally, in vitro mineralization was greatly...

  9. Cell saver filtering of extravasated rhBMP-2 after degenerative scoliosis reconstruction

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    Gabriel Liu, MBBCh, MSc, FRCS, FAMS (Orth

    2015-06-01

    Full Text Available RhBMP-2 is a bone fusion enhancer commonly used in scoliosis reconstruction surgery. It is delivered via an absorbable collagen sponge but has been known to migrate away from its delivery site. RhBMP-2 extravasation in surgical drainage has been noted during first two days post-surgery. Cell savers are widely used in scoliosis reconstruction to limit transfusion requirements and are commonly deployed in cases where rhBMP-2 is used for fusion augmentation. It is not known whether rhBMP-2 is present in salvaged blood or filtered away during cell saver recycling. Through this case series of four patients who underwent scoliosis reconstruction, we assess cell saver efficacy in filtering rhBMP-2 molecules by quantifying the amount of rhBMP-2 present in salvaged blood obtained after postoperative drainage recycling by OrthoPAT® cell saver and comparing it to rhBMP-2 leakage in postoperative drainage without cell saver recycling. We report an almost 10-fold reduction of rhBMP-2 concentration in salvaged blood obtained after cell saver recycling of postoperative drainage, suggesting cell saver effectiveness in filtering rhBMP-2 molecules.

  10. Bmp2 deletion causes an amelogenesis imperfecta phenotype via regulating enamel gene expression.

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    Guo, Feng; Feng, Junsheng; Wang, Feng; Li, Wentong; Gao, Qingping; Chen, Zhuo; Shoff, Lisa; Donly, Kevin J; Gluhak-Heinrich, Jelica; Chun, Yong Hee Patricia; Harris, Stephen E; MacDougall, Mary; Chen, Shuo

    2015-08-01

    Although Bmp2 is essential for tooth formation, the role of Bmp2 during enamel formation remains unknown in vivo. In this study, the role of Bmp2 in regulation of enamel formation was investigated by the Bmp2 conditional knock out (Bmp2 cKO) mice. Teeth of Bmp2 cKO mice displayed severe and profound phenotypes with asymmetric and misshaped incisors as well as abrasion of incisors and molars. Scanning electron microscopy analysis showed that the enamel layer was hypoplastic and enamel lacked a typical prismatic pattern. Teeth from null mice were much more brittle as tested by shear and compressive moduli. Expression of enamel matrix protein genes, amelogenin, enamelin, and enamel-processing proteases, Mmp-20 and Klk4 was reduced in the Bmp2 cKO teeth as reflected in a reduced enamel formation. Exogenous Bmp2 up-regulated those gene expressions in mouse enamel organ epithelial cells. This result for the first time indicates Bmp2 signaling is essential for proper enamel development and mineralization in vivo. © 2015 Wiley Periodicals, Inc.

  11. Alveolar ridge and maxillary sinus augmentation using rhBMP-2: a systematic review.

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    Freitas, Rubens Moreno de; Spin-Neto, Rubens; Marcantonio Junior, Elcio; Pereira, Luís Antônio Violin Dias; Wikesjö, Ulf M E; Susin, Cristiano

    2015-01-01

    The aim of this systematic review was to evaluate clinical and safety data for recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier when used for alveolar ridge/maxillary sinus augmentation in humans. Clinical studies/case series published 1980 through June 2012 using rhBMP-2/ACS were searched. Studies meeting the following criteria were considered eligible for inclusion: >10 subjects at baseline and maxillary sinus or alveolar ridge augmentation not concomitant with implant placement. Seven of 69 publications were eligible for review. rhBMP-2/ACS yielded clinically meaningful bone formation for maxillary sinus augmentation that would allow placement of regular dental implants without consistent differences between rhBMP-2 concentrations. Nevertheless, the statistical analysis showed that sinus augmentation following autogenous bone graft was significantly greater (mean bone height: 1.6 mm, 95% CI: 0.5-2.7 mm) than for rhBMP-2/ACS (rhBMP-2 at 1.5 mg/mL). In extraction sockets, rhBMP-2/ACS maintained alveolar ridge height while enhancing alveolar ridge width. Safety reports did not represent concerns for the proposed indications. rhBMP-2/ACS appears a promising alternative to autogenous bone grafts for alveolar ridge/maxillary sinus augmentation; dose and carrier optimization may expand its efficacy, use, and clinical application. © 2013 Wiley Periodicals, Inc.

  12. Immortalization and characterization of mouse floxed Bmp2/4 osteoblasts

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    Wu, Li-An; Yuan, Guohua; Yang, Guobin; Ortiz-Gonzalez, Iris; Yang, Wuchen; Cui, Yong; MacDougall, Mary; Donly, Kevin J.; Harris, Stephen; Chen, Shuo

    2009-01-01

    Generation of a floxed Bmp2/4 osteoblast cell line is a valuable tool for studying the modulatory effects of Bmp2 and Bmp4 on osteoblast differentiation as well as relevant molecular events. In this study, primary floxed Bmp2/4 mouse osteoblasts were cultured and transfected with simian virus 40 large T-antigen. Transfection was verified by polymerase chain reaction (PCR) and immunohistochemistry. To examine the characteristics of the transfected cells, morphology, proliferation and mineralization were analyzed, expression of cell-specific genes including Runx2, ATF4, Dlx3, Osx, dentin matrix protein 1, bone sialoprotein, osteopontin, osteocalcin, osteonectin and collagen type I was detected. These results show that transfected floxed Bmp2/4 osteoblasts bypassed senescence with a higher proliferation rate, but retain the genotypic and phenotypic characteristics similar to the primary cells. Thus, we for the first time demonstrate the establishment of an immortalized mouse floxed Bmp2/4 osteoblast cell line.

  13. Immortalization and characterization of mouse floxed Bmp2/4 osteoblasts

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    Wu, Li-An [Department of Pediatric Dentistry, The University of Texas Health Science Center at San Antonio, TX (United States); Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University, Xi-an (China); Yuan, Guohua; Yang, Guobin [Department of Pediatric Dentistry, The University of Texas Health Science Center at San Antonio, TX (United States); Key Laboratory of Oral Biomedical Engineering Ministry of Education, Wuhan (China); Ortiz-Gonzalez, Iris [Department of Pediatric Dentistry, The University of Texas Health Science Center at San Antonio, TX (United States); Yang, Wuchen; Cui, Yong [Department of Periodontics, Dental School, The University of Texas Health Science Center at San Antonio, TX (United States); MacDougall, Mary [Department of Oral/Maxillofacial Surgery, University of Alabama, Birmingham, AL (United States); Donly, Kevin J. [Department of Pediatric Dentistry, The University of Texas Health Science Center at San Antonio, TX (United States); Harris, Stephen [Department of Periodontics, Dental School, The University of Texas Health Science Center at San Antonio, TX (United States); Chen, Shuo, E-mail: chens0@uthscsa.edu [Department of Pediatric Dentistry, The University of Texas Health Science Center at San Antonio, TX (United States)

    2009-08-14

    Generation of a floxed Bmp2/4 osteoblast cell line is a valuable tool for studying the modulatory effects of Bmp2 and Bmp4 on osteoblast differentiation as well as relevant molecular events. In this study, primary floxed Bmp2/4 mouse osteoblasts were cultured and transfected with simian virus 40 large T-antigen. Transfection was verified by polymerase chain reaction (PCR) and immunohistochemistry. To examine the characteristics of the transfected cells, morphology, proliferation and mineralization were analyzed, expression of cell-specific genes including Runx2, ATF4, Dlx3, Osx, dentin matrix protein 1, bone sialoprotein, osteopontin, osteocalcin, osteonectin and collagen type I was detected. These results show that transfected floxed Bmp2/4 osteoblasts bypassed senescence with a higher proliferation rate, but retain the genotypic and phenotypic characteristics similar to the primary cells. Thus, we for the first time demonstrate the establishment of an immortalized mouse floxed Bmp2/4 osteoblast cell line.

  14. Construction of doxycycline-mediated BMP-2 transgene combining with APA microcapsules for bone repair.

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    Qian, Dongyang; Bai, Bo; Yan, Guangbin; Zhang, Shujiang; Liu, Qi; Chen, Yi; Tan, Xiaobo; Zeng, Yanjun

    2016-01-01

    The repairing of large segmental bone defects is difficult for clinical orthopedists at present. Gene therapy is regarded as a promising method for bone defects repair. The present study aimed to construct an effective and controllable Tet-On expression system for transferring hBMP-2 gene into bone marrow mesenchymal progenitor cells (BMSCs). Meanwhile, with combination of alginate-poly-L-lysine-alginate (APA) microencapsulation technology, we attempted to reduce the influence of immunologic rejection and examine the effect of the Tet-On expression system on osteogenesis of BMSCs. The adenovirus encoding hBMP-2 (ADV-hBMP2) was constructed using the means of molecular cloning. The ADV-hBMP2 and Adeno-X Tet-On virus was respectively transfected to the HEK293 for amplification and afterward BMSCs were co-infected with the virus of ADV-hBMP2 and the Adeno-X Tet-On. The expression of hBMP-2 was measured with induction by doxycycline (DOX) at different concentration by means of RT-PCR and ELISA. Combining Tet-On expression system and APA microcapsules with the use of the pulsed high-voltage electrostatic microcapsule instrument, we examined the expression level of hBMP-2 in APA microcapsules by ELISA as well as the osteogenesis by alizarin red S staining. An effective Tet-On expression system for transferring hBMP-2 gene into BMSCs was constructed successfully. Also, the expression of hBMP-2 could be regulated by concentration of DOX. The data exhibited that BMSCs in APA microcapsules maintained the capability of proliferation and differentiation. The combination of Tet-On expression system and APA microcapsules could promote the osteogenesis of BMSCs. According to the results, microencapsulated Tet-On expression system showed the effective characteristics of secreting hBMP-2 and enhancing osteogenesis, which would provide a promising way for bone repair.

  15. Comparison of the osteogenesis and fusion rates between activin A/BMP-2 chimera (AB204) and rhBMP-2 in a beagle's posterolateral lumbar spine model.

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    Zheng, Guang Bin; Yoon, Byung-Hak; Lee, Jae Hyup

    2017-10-01

    Activin A/BMP-2 chimera (AB204) could promote bone healing more effectively than recombinant bone morphogenetic protein 2 (rhBMP-2) with much lower dose in a rodent model, but there is no report about the effectiveness of AB204 in a large animal model. The purpose of this study was to compare the osteogenesis and fusion rate between AB204 and rhBMP-2 using biphasic calcium phosphate (BCP) as a carrier in a beagle's posterolateral lumbar fusion model. This is a randomized control animal study. Seventeen male beagle dogs were included. Bilateral posterolateral fusion was performed at the L1-L2 and L4-L5 levels. Biphasic calcium phosphate (2 cc), rhBMP-2 (50 µg)+BCP (2 cc), or AB204 (50 µg)+BCP (2 cc) were implanted into the intertransverse space randomly. X-ray was performed at 4 and 8 weeks. After 8 weeks, the animals were sacrificed, and new bone formation and fusion rate were evaluated by manual palpation, computed tomography (CT), and undecalcified histology. The AB204 group showed significantly higher fusion rate (90%) than the rhBMP-2 group (15%) or the Osteon group (6.3%) by manual palpation. On x-ray and CT assessment, fusion rate and the volume of newly formed bone were also significantly higher in AB204 group than other groups. In contrast, more osteolysis was found in rhBMP-2 group (40%) than in AB204 group (10%) on CT study. In histologic results, new bone formation was sufficient between transverse processes in AB204 group, and obvious trabeculation and bone remodeling were observed. But in rhBMP-2 group, new bone formation was less than AB204 group and osteolysis was observed between the intertransverse spaces. A low dose of AB204 with BCP as a carrier significantly promotes the fusion rate in a large animal model when compared with the rhBMP-2. These findings demonstrate that AB204 could be an alternative to rhBMP-2 to improve fusion rate. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Low-intensity pulsed ultrasound accelerates tooth movement via activation of the BMP-2 signaling pathway.

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    Hui Xue

    Full Text Available The present study was designed to determine the underlying mechanism of low-intensity pulsed ultrasound (LIPUS induced alveolar bone remodeling and the role of BMP-2 expression in a rat orthodontic tooth movement model. Orthodontic appliances were placed between the homonymy upper first molars and the upper central incisors in rats under general anesthesia, followed by daily 20-min LIPUS or sham LIPUS treatment beginning at day 0. Tooth movement distances and molecular changes were evaluated at each observation point. In vitro and in vivo studies were conducted to detect HGF (Hepatocyte growth factor/Runx2/BMP-2 signaling pathways and receptor activator of NFκB ligand (RANKL expression by quantitative real time PCR (qRT-PCR, Western blot and immunohistochemistry. At day 3, LIPUS had no effect on the rat orthodontic tooth movement distance and BMP-2-induced alveolar bone remodeling. However, beginning at day 5 and for the following time points, LIPUS significantly increased orthodontic tooth movement distance and BMP-2 signaling pathway and RANKL expression compared with the control group. The qRT-PCR and Western blot data in vitro and in vivo to study BMP-2 expression were consistent with the immunohistochemistry observations. The present study demonstrates that LIPUS promotes alveolar bone remodeling by stimulating the HGF/Runx2/BMP-2 signaling pathway and RANKL expression in a rat orthodontic tooth movement model, and LIPUS increased BMP-2 expression via Runx2 regulation.

  17. BMP2-loaded hollow hydroxyapatite microspheres exhibit enhanced osteoinduction and osteogenicity in large bone defects.

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    Xiong, Long; Zeng, Jianhua; Yao, Aihua; Tu, Qiquan; Li, Jingtang; Yan, Liang; Tang, Zhiming

    2015-01-01

    The regeneration of large bone defects is an osteoinductive, osteoconductive, and osteogenic process that often requires a bone graft for support. Limitations associated with naturally autogenic or allogenic bone grafts have demonstrated the need for synthetic substitutes. The present study investigates the feasibility of using novel hollow hydroxyapatite microspheres as an osteoconductive matrix and a carrier for controlled local delivery of bone morphogenetic protein 2 (BMP2), a potent osteogenic inducer of bone regeneration. Hollow hydroxyapatite microspheres (100±25 μm) with a core (60±18 μm) and a mesoporous shell (180±42 m(2)/g surface area) were prepared by a glass conversion technique and loaded with recombinant human BMP2 (1 μg/mg). There was a gentle burst release of BMP2 from microspheres into the surrounding phosphate-buffered saline in vitro within the initial 48 hours, and continued at a low rate for over 40 days. In comparison with hollow hydroxyapatite microspheres without BMP2 or soluble BMP2 without a carrier, BMP2-loaded hollow hydroxyapatite microspheres had a significantly enhanced capacity to reconstitute radial bone defects in rabbit, as shown by increased serum alkaline phosphatase; quick and complete new bone formation within 12 weeks; and great biomechanical flexural strength. These results indicate that BMP2-loaded hollow hydroxyapatite microspheres could be a potential new option for bone graft substitutes in bone regeneration.

  18. Immobilization of Murine Anti-BMP-2 Monoclonal Antibody on Various Biomaterials for Bone Tissue Engineering

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    Sahar Ansari

    2014-01-01

    Full Text Available Biomaterials are widely used as scaffolds for tissue engineering. We have developed a strategy for bone tissue engineering that entails application of immobilized anti-BMP-2 monoclonal antibodies (mAbs to capture endogenous BMPs in vivo and promote antibody-mediated osseous regeneration (AMOR. The purpose of the current study was to compare the efficacy of immobilization of a specific murine anti-BMP-2 mAb on three different types of biomaterials and to evaluate their suitability as scaffolds for AMOR. Anti-BMP-2 mAb or isotype control mAb was immobilized on titanium (Ti microbeads, alginate hydrogel, and ACS. The treated biomaterials were surgically implanted in rat critical-sized calvarial defects. After 8 weeks, de novo bone formation was assessed using micro-CT and histomorphometric analyses. Results showed de novo bone regeneration with all three scaffolds with immobilized anti-BMP-2 mAb, but not isotype control mAb. Ti microbeads showed the highest volume of bone regeneration, followed by ACS. Alginate showed the lowest volume of bone. Localization of BMP-2, -4, and -7 antigens was detected on all 3 scaffolds with immobilized anti-BMP-2 mAb implanted in calvarial defects. Altogether, these data suggested a potential mechanism for bone regeneration through entrapment of endogenous BMP-2, -4, and -7 proteins leading to bone formation using different types of scaffolds via AMOR.

  19. BMP-2 Induced Expression of Alx3 That Is a Positive Regulator of Osteoblast Differentiation.

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    Takashi Matsumoto

    Full Text Available Bone morphogenetic proteins (BMPs regulate many aspects of skeletal development, including osteoblast and chondrocyte differentiation, cartilage and bone formation, and cranial and limb development. Among them, BMP-2, one of the most potent osteogenic signaling molecules, stimulates osteoblast differentiation, while it inhibits myogenic differentiation in C2C12 cells. To evaluate genes involved in BMP-2-induced osteoblast differentiation, we performed cDNA microarray analyses to compare BMP-2-treated and -untreated C2C12 cells. We focused on Alx3 (aristaless-like homeobox 3 which was clearly induced during osteoblast differentiation. Alx3, a homeobox gene related to the Drosophilaaristaless gene, has been linked to developmental functions in craniofacial structures and limb development. However, little is known about its direct relationship with bone formation. In the present study, we focused on the mechanisms of Alx3 gene expression and function during osteoblast differentiation induced by BMP-2. In C2C12 cells, BMP-2 induced increase of Alx3 gene expression in both time- and dose-dependent manners through the BMP receptors-mediated SMAD signaling pathway. In addition, silencing of Alx3 by siRNA inhibited osteoblast differentiation induced by BMP-2, as showed by the expressions of alkaline phosphatase (Alp, Osteocalcin, and Osterix, while over-expression of Alx3 enhanced osteoblast differentiation induced by BMP-2. These results indicate that Alx3 expression is enhanced by BMP-2 via the BMP receptors mediated-Smad signaling and that Alx3 is a positive regulator of osteoblast differentiation induced by BMP-2.

  20. BMP-2 Overexpression Augments Vascular Smooth Muscle Cell Motility by Upregulating Myosin Va via Erk Signaling

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    Ming Zhang

    2014-01-01

    Full Text Available Background. The disruption of physiologic vascular smooth muscle cell (VSMC migration initiates atherosclerosis development. The biochemical mechanisms leading to dysfunctional VSMC motility remain unknown. Recently, cytokine BMP-2 has been implicated in various vascular physiologic and pathologic processes. However, whether BMP-2 has any effect upon VSMC motility, or by what manner, has never been investigated. Methods. VSMCs were adenovirally transfected to genetically overexpress BMP-2. VSMC motility was detected by modified Boyden chamber assay, confocal time-lapse video assay, and a colony wounding assay. Gene chip array and RT-PCR were employed to identify genes potentially regulated by BMP-2. Western blot and real-time PCR detected the expression of myosin Va and the phosphorylation of extracellular signal-regulated kinases 1/2 (Erk1/2. Immunofluorescence analysis revealed myosin Va expression locale. Intracellular Ca2+ oscillations were recorded. Results. VSMC migration was augmented in VSMCs overexpressing BMP-2 in a dose-dependent manner. siRNA-mediated knockdown of myosin Va inhibited VSMC motility. Both myosin Va mRNA and protein expression significantly increased after BMP-2 administration and were inhibited by Erk1/2 inhibitor U0126. BMP-2 induced Ca2+ oscillations, generated largely by a “cytosolic oscillator”. Conclusion. BMP-2 significantly increased VSMCs migration and myosin Va expression, via the Erk signaling pathway and intracellular Ca2+ oscillations. We provide additional insight into the pathophysiology of atherosclerosis, and inhibition of BMP-2-induced myosin Va expression may represent a potential therapeutic strategy.

  1. Site-Directed Immobilization of BMP-2: Two Approaches for the Production of Innovative Osteoinductive Scaffolds.

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    Tabisz, Barbara; Schmitz, Werner; Schmitz, Michael; Luehmann, Tessa; Heusler, Eva; Rybak, Jens-Christoph; Meinel, Lorenz; Fiebig, Juliane E; Mueller, Thomas D; Nickel, Joachim

    2017-03-13

    The regenerative potential of bone is strongly impaired in pathological conditions, such as nonunion fractures. To support bone regeneration various scaffolds have been developed in the past, which have been functionalized with osteogenic growth factors such as bone morphogenetic proteins (BMPs). However, most of them required supra-physiological levels of these proteins leading to burst releases, thereby causing severe side effects. Site-specific, covalent coupling of BMP2 to implant materials might be an optimal strategy in order to overcome these problems. Therefore, we created a BMP-2 variant (BMP2-K3Plk) containing a noncanonical amino acid (propargyl-l-lysine) substitution introduced by genetic code expansion that allows for site-specific and covalent immobilization onto polymeric scaffold materials. To directly compare different coupling strategies, we also produced a BMP2 variant containing an additional cysteine residue (BMP2-A2C) allowing covalent coupling by thioether formation. The BMP2-K3Plk mutant was coupled to functionalized beads by a copper-catalyzed azide-alkyne cycloaddition (CuAAC) either directly or via a short biotin-PEG linker both with high specificity. After exposing the BMP-coated beads to C2C12 cells, ALP expression appeared locally restricted in close proximity to these beads, showing that both coupled BMP2 variants trigger cell differentiation. The advantage of our approach over non-site-directed immobilization techniques is the ability to produce fully defined osteogenic surfaces, allowing for lower BMP2 loads and concomitant higher bioactivities, for example, due to controlled orientation toward BMP2 receptors. Such products might provide superior bone healing capabilities with potential safety advantages as of homogeneous product outcome.

  2. Quick change: post-transcriptional regulation in Pseudomonas.

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    Grenga, Lucia; Little, Richard H; Malone, Jacob G

    2017-08-01

    Pseudomonas species have evolved dynamic and intricate regulatory networks to fine-tune gene expression, with complex regulation occurring at every stage in the processing of genetic information. This approach enables Pseudomonas to generate precise individual responses to the environment in order to improve their fitness and resource economy. The weak correlations we observe between RNA and protein abundance highlight the significant regulatory contribution of a series of intersecting post-transcriptional pathways, influencing mRNA stability, translational activity and ribosome function, to Pseudomonas environmental responses. This review examines our current understanding of three major post-transcriptional regulatory systems in Pseudomonas spp.; Gac/Rsm, Hfq and RimK, and presents an overview of new research frontiers, emerging genome-wide methodologies, and their potential for the study of global regulatory responses in Pseudomonas. © FEMS 2017.

  3. Post-transcriptional regulation of gene expression in Yersinia species

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    Chelsea A Schiano

    2012-11-01

    Full Text Available Proper regulation of gene expression is required by bacterial pathogens to respond to continually changing environmental conditions and the host response during the infectious process. While transcriptional regulation is perhaps the most well understood form of controlling gene expression, recent studies have demonstrated the importance of post-transcriptional mechanisms of gene regulation that allow for more refined management of the bacterial response to host conditions. Yersinia species of bacteria are known to use various forms of post-transcriptional regulation for control of many virulence-associated genes. These include regulation by cis- and trans-acting small non-coding RNAs, RNA-binding proteins, RNases, and thermoswitches. The effects of these and other regulatory mechanisms on Yersinia physiology can be profound and have been shown to influence type III secretion, motility, biofilm formation, host cell invasion, intracellular survival and replication, and more. In this review, we will discuss these and other post-transcriptional mechanisms and their influence on virulence gene regulation, with a particular emphasis on how these processes influence the virulence of Yersinia in the host.

  4. BMP-2 induces EMT and breast cancer stemness through Rb and CD44

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    Huang, Peide; Chen, Anan; He, Weiyi

    2017-01-01

    Bone morphogenetic protein 2 (BMP-2) has been reported to facilitate epithelial-to-mesenchymal transition (EMT) and bone metastasis in breast cancer xenograft models. To investigate the role of BMP-2 in the development of breast cancer stem cells (BCSCs), and to further elucidate the mechanisms u...... then contribute to breast cancer metastasis. These findings may be helpful for developing new strategies for the treatment and prognosis of advanced breast cancer....

  5. Bmp 2 and bmp 7 induce odonto- and osteogenesis of human tooth germ stem cells.

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    Taşlı, P Neslihan; Aydın, Safa; Yalvaç, Mehmet Emir; Sahin, Fikrettin

    2014-03-01

    Bone morphogenetic proteins (BMPs) initiate, promote, and maintain odontogenesis and osteogenesis. In this study, we studied the effect of bone morphogenic protein 2 (BMP 2) and bone morphogenic protein 7 (BMP 7) as differentiation inducers in tooth and bone regeneration. We compared the effect of BMP 2 and BMP 7 on odontogenic and osteogenic differentiation of human tooth germ stem cells (hTGSCs). Third molar-derived hTGSCs were characterized with mesenchymal stem cell surface markers by flow cytometry. BMP 2 and BMP 7 were transfected into hTGSCs and the cells were seeded onto six-well plates. One day after the transfection, hTGSCs were treated with odontogenic and osteogenic mediums for 14 days. For confirmation of odontogenic and osteogenic differentiation, mRNA levels of BMP2, BMP 7, collagen type 1 (COL1A), osteocalsin (OCN), and dentin sialophosphoprotein (DSPP) genes were measured by quantitative real-time PCR. In addition to this, immunocytochemistry was performed by odontogenic and osteogenic antibodies and mineralization obtained by von Kossa staining. Our results showed that the BMP 2 and BMP 7 both promoted odontogenic and osteogenic differentiation of hTGSCs. Data indicated that BMP 2 treatment and BMP 7 treatment induce odontogenic differentiation without affecting each other, whereas they induce osteogenic differentiation by triggering expression of each other. These findings provide a feasible tool for tooth and bone tissue engineering.

  6. Sustained release of BMP-2 in bioprinted alginate for osteogenicity in mice and rats.

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    Michelle T Poldervaart

    Full Text Available The design of bioactive three-dimensional (3D scaffolds is a major focus in bone tissue engineering. Incorporation of growth factors into bioprinted scaffolds offers many new possibilities regarding both biological and architectural properties of the scaffolds. This study investigates whether the sustained release of bone morphogenetic protein 2 (BMP-2 influences osteogenicity of tissue engineered bioprinted constructs. BMP-2 loaded on gelatin microparticles (GMPs was used as a sustained release system, which was dispersed in hydrogel-based constructs and compared to direct inclusion of BMP-2 in alginate or control GMPs. The constructs were supplemented with goat multipotent stromal cells (gMSCs and biphasic calcium phosphate to study osteogenic differentiation and bone formation respectively. BMP-2 release kinetics and bioactivity showed continuous release for three weeks coinciding with osteogenicity. Osteogenic differentiation and bone formation of bioprinted GMP containing constructs were investigated after subcutaneous implantation in mice or rats. BMP-2 significantly increased bone formation, which was not influenced by the release timing. We showed that 3D printing of controlled release particles is feasible and that the released BMP-2 directs osteogenic differentiation in vitro and in vivo.

  7. Effect of a Novel Nonviral Gene Delivery of BMP-2 on Bone Healing

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    P. Schwabe

    2012-01-01

    Full Text Available Background. Gene therapeutic drug delivery approaches have been introduced to improve the efficiency of growth factors at the site of interest. This study investigated the efficacy and safety of a new nonviral copolymer-protected gene vector (COPROG for the stimulation of bone healing. Methods. In vitro, rat osteoblasts were transfected with COPROG + luciferase plasmid or COPROG + hBMP-2 plasmid. In vivo, rat tibial fractures were intramedullary stabilized with uncoated versus COPROG+hBMP-2-plasmid-coated titanium K-wires. The tibiae were prepared for biomechanical and histological analyses at days 28 and 42 and for transfection/safety study at days 2, 4, 7, 28, and 42. Results. In vitro results showed luciferase expression until day 21, and hBMP-2-protein was measured from day 2 – day 10. In vivo, the local application of hBMP-2-plasmid showed a significantly higher maximum load after 42 days compared to that in the control. The histomorphometric analysis revealed a significantly less mineralized periosteal callus area in the BMP-2 group compared to the control at day 28. The rt-PCR showed no systemic biodistribution of luciferase RNA. Conclusion. A positive effect on fracture healing by nonviral BMP-2 plasmid application from COPROG-coated implants could be shown in this study; however, the effect of the vector may be improved with higher plasmid concentrations. Transfection showed no biodistribution to distant organs and was considered to be safe.

  8. Functionalization of PCL-3D Electrospun Nanofibrous Scaffolds for Improved BMP2-Induced Bone Formation.

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    Miszuk, Jacob M; Xu, Tao; Yao, Qingqing; Fang, Fang; Childs, Josh D; Hong, Zhongkui; Tao, Jianning; Fong, Hao; Sun, Hongli

    2018-03-01

    Bone morphogenic protein 2 (BMP2) is a key growth factor for bone regeneration, possessing FDA approval for orthopedic applications. BMP2 is often required in supratherapeutic doses clinically, yielding adverse side effects and substantial treatment costs. Considering the crucial role of materials for BMPs delivery and cell osteogenic differentiation, we devote to engineering an innovative bone-matrix mimicking niche to improve low dose of BMP2-induced bone formation. Our previous work describes a novel technique, named thermally induced nanofiber self-agglomeration (TISA), for generating 3D electrospun nanofibrous (NF) polycaprolactone (PCL) scaffolds. TISA process could readily blend PCL with PLA, leading to increased osteogenic capabilities in vitro , however, these bio-inert synthetic polymers produced limited BMP2-induced bone formation in vivo. We therefore hypothesize that functionalization of NF 3D PCL scaffolds with bone-like hydroxyapatite (HA) and BMP2 signaling activator phenamil will provide a favorable osteogenic niche for bone formation at low doses of BMP2. Compared to PCL-3D scaffolds, PCL/HA-3D scaffolds demonstrated synergistically enhanced osteogenic differentiation capabilities of C2C12 cells with phenamil. Importantly, in vivo studies showed this synergism was able to generate significantly increased new bone in an ectopic mouse model, suggesting PCL/HA-3D scaffolds act as a favorable synthetic extracellular matrix for bone regeneration.

  9. Post-transcriptional trafficking and regulation of neuronal gene expression.

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    Goldie, Belinda J; Cairns, Murray J

    2012-02-01

    Intracellular messenger RNA (mRNA) traffic and translation must be highly regulated, both temporally and spatially, within eukaryotic cells to support the complex functional partitioning. This capacity is essential in neurons because it provides a mechanism for rapid input-restricted activity-dependent protein synthesis in individual dendritic spines. While this feature is thought to be important for synaptic plasticity, the structures and mechanisms that support this capability are largely unknown. Certainly specialized RNA binding proteins and binding elements in the 3' untranslated region (UTR) of translationally regulated mRNA are important, but the subtlety and complexity of this system suggests that an intermediate "specificity" component is also involved. Small non-coding microRNA (miRNA) are essential for CNS development and may fulfill this role by acting as the guide strand for mediating complex patterns of post-transcriptional regulation. In this review we examine post-synaptic gene regulation, mRNA trafficking and the emerging role of post-transcriptional gene silencing in synaptic plasticity.

  10. Binding Interactions of Keratin-Based Hair Fiber Extract to Gold, Keratin, and BMP-2.

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    Roche C de Guzman

    Full Text Available Hair-derived keratin biomaterials composed mostly of reduced keratin proteins (kerateines have demonstrated their utility as carriers of biologics and drugs for tissue engineering. Electrostatic forces between negatively-charged keratins and biologic macromolecules allow for effective drug retention; attraction to positively-charged growth factors like bone morphogenetic protein 2 (BMP-2 has been used as a strategy for osteoinduction. In this study, the intermolecular surface and bulk interaction properties of kerateines were investigated. Thiol-rich kerateines were chemisorbed onto gold substrates to form an irreversible 2-nm rigid layer for surface plasmon resonance analysis. Kerateine-to-kerateine cohesion was observed in pH-neutral water with an equilibrium dissociation constant (KD of 1.8 × 10(-4 M, indicating that non-coulombic attractive forces (i.e. hydrophobic and van der Waals were at work. The association of BMP-2 to kerateine was found to be greater (KD = 1.1 × 10(-7 M, within the range of specific binding. Addition of salts (phosphate-buffered saline; PBS shortened the Debye length or the electrostatic field influence which weakened the kerateine-BMP-2 binding (KD = 3.2 × 10(-5 M. BMP-2 in bulk kerateine gels provided a limited release in PBS (~ 10% dissociation in 4 weeks, suggesting that electrostatic intermolecular attraction was significant to retain BMP-2 within the keratin matrix. Complete dissociation between kerateine and BMP-2 occurred when the PBS pH was lowered (to 4.5, below the keratin isoelectric point of 5.3. This phenomenon can be attributed to the protonation of keratin at a lower pH, leading to positive-positive repulsion. Therefore, the dynamics of kerateine-BMP-2 binding is highly dependent on pH and salt concentration, as well as on BMP-2 solubility at different pH and molarity. The study findings may contribute to our understanding of the release kinetics of drugs from keratin biomaterials and allow for the

  11. Synthetic scaffold coating with adeno-associated virus encoding BMP2 to promote endogenous bone repair.

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    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.

  12. BMP2 induces PANC-1 cell invasion by MMP-2 overexpression through ROS and ERK.

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    Liu, Jun; Ben, Qi-Wen; Yao, Wei-Yan; Zhang, Jian-Jun; Chen, Da-Fan; He, Xiang-Yi; Li, Lei; Yuan, Yao-Zong

    2012-06-01

    The emerging roles of bone morphogenetic proteins (BMPs) in the initiation and progression of multiple cancers have drawn great attention in cancer research. We hypothesized that BMP2 promotes cancer metastasis by modulating MMP-2 secretion and activity through intracellular ROS regulation and ERK activation in human pancreatic cancer. Our data show that stimulation of PANC-1 cells with BMP2 induced MMP-2 secretion and activation, associated with decreased E-cadherin expression, resulting in epithelial-to-mesenchymal transformation (EMT) and cell invasion. Blockade of ROS by the ROS scavenger, 2-MPG, abolished cell invasion, inhibited the EMT process and decreased MMP-2 expression, suggesting ROS accumulation caused an increase in MMP-2 expression in BMP2-stimulated PANC-1 cell invasion. Furthermore, treatment of PANC-1 cells with 2-MPG or ERK inhibitor PD98059 reduced the phosphorylation of ERK, resulting in attenuation of BMP2-induced cell invasion and MMP-2 activation. Taken together, these results suggest that BMP2 induces the cell invasion of PANC-1 cells by enhancing MMP-2 secretion and acting through ROS accumulation and ERK activation.

  13. Bone Morphogenic Protein-2 (rhBMP2)-Loaded Silk Fibroin Scaffolds to Enhance the Osteoinductivity in Bone Tissue Engineering

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    Du, Guang-Yu; He, Sheng-Wei; Sun, Chuan-Xiu; Mi, Li-Dong

    2017-10-01

    There is an increasing demand for formulations of silk fibroin (SF) scaffolds in biomedical applications. SF was crosslinked via glutaraldehyde with osteoinductive recombinant human bone morphogenic protein-2 (rhBMP2) of different ratios viz. (i) 3% SF with no rhBMP2 (SF), (ii) 3% SF with equal amount of rhBMP2 (SF+BMP2), and (iii) 12% SF with 3% of rhBMP2 (4SF+BMP2), and these solutions were used in electrospinning-based fabrication of nanoscaffolds for evaluating increased osteoinductive potential of SF scaffolds with rhBMP2. Stress-strain relationship suggested there is no loss in mechanical strength of fibers with addition of rhBMP2, and mechanical strength of scaffold was improved with increase in concentration of SF. rhBMP2 association increased the water retention capacity of scaffold as evident from swelling studies. Viability of hMSCs was found to be higher in conjugated scaffolds, and scaffolds do not exhibit any cytotoxicity towards guest cells. Cells were found to have higher alkaline phosphatase activity in conjugated scaffolds under in vitro and in vivo conditions which establishes the increased osteoinductivity of the novel construct. The scaffolds were found to be effective for in vivo bone formation as well.

  14. Bmp2 in osteoblasts of periosteum and trabecular bone links bone formation to vascularization and mesenchymal stem cells

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    Yang, Wuchen; Guo, Dayong; Harris, Marie A.; Cui, Yong; Gluhak-Heinrich, Jelica; Wu, Junjie; Chen, Xiao-Dong; Skinner, Charles; Nyman, Jeffry S.; Edwards, James R.; Mundy, Gregory R.; Lichtler, Alex; Kream, Barbara E.; Rowe, David W.; Kalajzic, Ivo; David, Val; Quarles, Darryl L.; Villareal, Demetri; Scott, Greg; Ray, Manas; Liu, S.; Martin, James F.; Mishina, Yuji; Harris, Stephen E.

    2013-01-01

    Summary We generated a new Bmp2 conditional-knockout allele without a neo cassette that removes the Bmp2 gene from osteoblasts (Bmp2-cKOob) using the 3.6Col1a1-Cre transgenic model. Bones of Bmp2-cKOob mice are thinner, with increased brittleness. Osteoblast activity is reduced as reflected in a reduced bone formation rate and failure to differentiate to a mature mineralizing stage. Bmp2 in osteoblasts also indirectly controls angiogenesis in the periosteum and bone marrow. VegfA production is reduced in Bmp2-cKOob osteoblasts. Deletion of Bmp2 in osteoblasts also leads to defective mesenchymal stem cells (MSCs), which correlates with the reduced microvascular bed in the periosteum and trabecular bones. Expression of several MSC marker genes (α-SMA, CD146 and Angiopoietin-1) in vivo, in vitro CFU assays and deletion of Bmp2 in vitro in α-SMA+ MSCs support our conclusions. Critical roles of Bmp2 in osteoblasts and MSCs are a vital link between bone formation, vascularization and mesenchymal stem cells. PMID:23843612

  15. Expression of BMP-2 in Vascular Endothelial Cells of Recipient May Predict Delayed Graft Function After Renal Transplantation.

    Science.gov (United States)

    Basic-Jukic, Nikolina; Gulin, Marijana; Hudolin, Tvrtko; Kastelan, Zeljko; Katalinic, Lea; Coric, Marijana; Veda, Marija Varnai; Ivkovic, Vanja; Kes, Petar; Jelakovic, Bojan

    2016-01-01

    Delayed graft function (DGF) is associated with adverse outcomes after renal transplantation. Bone morphogenetic protein-2 (BMP-2) is involved in both endothelial function and immunological events. We compared expression of BMP-2 in epigastric artery of renal transplant recipients with immediate graft function (IGF) and DGF. 79 patients were included in this prospective study. Patients were divided in IGF group (64 patients) and DGF group (15 patients). BMP-2 expression in intima media (BMP2m) and endothelium (BMP2e) of epigastric artery was assessed by immunohistochemistry. Lower intensity of BMP2e staining was recorded in DGF compared to IGF. In DGF patients, 93% had no expression of BMP2e and 7% had 1st grade expression, compared to 45% and 41% in IGF group, respectively (P=0.001) (P<0.001 for no expression and P = 0.015 for 1st grade expression). Patients who had BMP2e staining positive had lower odds for DGF (OR 0.059 [0.007, 0.477]) and this remained significant even after adjustment for donor and recipient variables, cold ischemia time, and immunological matching (OR 0.038 [0.003, 0.492]). Our results demonstrate that BMP-2 expression in endothelial cells of epigastric arteries may predict development of DGF. © 2016 The Author(s) Published by S. Karger AG, Basel.

  16. Expression of BMP-2 in Vascular Endothelial Cells of Recipient May Predict Delayed Graft Function After Renal Transplantation

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    Nikolina Basic-Jukic

    2016-11-01

    Full Text Available Background/Aims: Delayed graft function (DGF is associated with adverse outcomes after renal transplantation. Bone morphogenetic protein-2 (BMP-2 is involved in both endothelial function and immunological events. We compared expression of BMP-2 in epigastric artery of renal transplant recipients with immediate graft function (IGF and DGF. Methods: 79 patients were included in this prospective study. Patients were divided in IGF group (64 patients and DGF group (15 patients. BMP-2 expression in intima media (BMP2m and endothelium (BMP2e of epigastric artery was assessed by immunohistochemistry. Results: Lower intensity of BMP2e staining was recorded in DGF compared to IGF. In DGF patients, 93% had no expression of BMP2e and 7% had 1st grade expression, compared to 45% and 41% in IGF group, respectively (P=0.001 (Pst grade expression. Patients who had BMP2e staining positive had lower odds for DGF (OR 0.059 [0.007, 0.477] and this remained significant even after adjustment for donor and recipient variables, cold ischemia time, and immunological matching (OR 0.038 [0.003, 0.492]. Conclusions: Our results demonstrate that BMP-2 expression in endothelial cells of epigastric arteries may predict development of DGF.

  17. rhBMP-2 for posterolateral instrumented lumbar fusion: a multicenter prospective randomized controlled trial.

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    Hurlbert, R John; Alexander, David; Bailey, Stewart; Mahood, James; Abraham, Ed; McBroom, Robert; Jodoin, Alain; Fisher, Charles

    2013-12-01

    Multicenter randomized controlled trial. To evaluate the effect of recombinant human bone morphogenetic protein (rhBMP-2) on radiographical fusion rate and clinical outcome for surgical lumbar arthrodesis compared with iliac crest autograft. In many types of spinal surgery, radiographical fusion is a primary outcome equally important to clinical improvement, ensuring long-term stability and axial support. Biologic induction of bone growth has become a commonly used adjunct in obtaining this objective. We undertook this study to objectify the efficacy of rhBMP-2 compared with traditional iliac crest autograft in instrumented posterolateral lumbar fusion. Patients undergoing 1- or 2-level instrumented posterolateral lumbar fusion were randomized to receive either autograft or rhBMP-2 for their fusion construct. Clinical and radiographical outcome measures were followed for 2 to 4 years postoperatively. One hundred ninety seven patients were successfully randomized among the 8 participating institutions. Adverse events attributable to the study drug were not significantly different compared with controls. However, the control group experienced significantly more graft-site complications as might be expected. 36-Item Short Form Health Survey, Oswestry Disability Index, and leg/back pain scores were comparable between the 2 groups. After 4 years of follow-up, radiographical fusion rates remained significantly higher in patients treated with rhBMP-2 (94%) than those who received autograft (69%) (P = 0.007). The use of rhBMP-2 for instrumented posterolateral lumbar surgery significantly improves the chances of radiographical fusion compared with the use of autograft. However, there is no associated improvement in clinical outcome within a 4-year follow-up period. These results suggest that use of rhBMP-2 should be considered in cases where lumbar arthrodesis is of primary concern.

  18. Perlecan domain 1 recombinant proteoglycan augments BMP-2 activity and osteogenesis

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    DeCarlo Arthur A

    2012-09-01

    Full Text Available Abstract Background Many growth factors, such as bone morphogenetic protein (BMP-2, have been shown to interact with polymers of sulfated disacharrides known as heparan sulfate (HS glycosaminoglycans (GAGs, which are found on matrix and cell-surface proteoglycans throughout the body. HS GAGs, and some more highly sulfated forms of chondroitin sulfate (CS, regulate cell function by serving as co-factors, or co-receptors, in GF interactions with their receptors, and HS or CS GAGs have been shown to be necessary for inducing signaling and GF activity, even in the osteogenic lineage. Unlike recombinant proteins, however, HS and CS GAGs are quite heterogenous due, in large part, to post-translational addition, then removal, of sulfate groups to various positions along the GAG polymer. We have, therefore, investigated whether it would be feasible to deliver a DNA pro-drug to generate a soluble HS/CS proteoglycan in situ that would augment the activity of growth-factors, including BMP-2, in vivo. Results Utilizing a purified recombinant human perlecan domain 1 (rhPln.D1 expressed from HEK 293 cells with HS and CS GAGs, tight binding and dose-enhancement of rhBMP-2 activity was demonstrated in vitro. In vitro, the expressed rhPln.D1 was characterized by modification with sulfated HS and CS GAGs. Dose-enhancement of rhBMP-2 by a pln.D1 expression plasmid delivered together as a lyophilized single-phase on a particulate tricalcium phosphate scaffold for 6 or more weeks generated up to 9 fold more bone volume de novo on the maxillary ridge in a rat model than in control sites without the pln.D1 plasmid. Using a significantly lower BMP-2 dose, this combination provided more than 5 times as much maxillary ridge augmentation and greater density than rhBMP-2 delivered on a collagen sponge (InFuse™. Conclusions A recombinant HS/CS PG interacted strongly and functionally with BMP-2 in binding and cell-based assays, and, in vivo, the pln.247 expression plasmid

  19. Dkk1 haploinsufficiency requires expression of Bmp2 for bone anabolic activity

    Science.gov (United States)

    Intini, Giuseppe; Nyman, Jeffry S.

    2015-01-01

    Bone fractures remain a serious health burden and prevention and enhanced healing of fractures has been obtained by augmenting either BMP or Wnt signaling. However, whether BMP and Wnt signaling are both required or are self-sufficient for anabolic and fracture healing activities has never been fully elucidated. Mice haploinsufficient for Dkk1 (Dkk1+/−) exhibit a high bone mass phenotype due to an up-regulation of canonical Wnt signaling while mice lacking Bmp2 expression in the limbs (Bmp2c/c;Prx1::cre) succumb to spontaneous fracture and are unable to initiate fracture healing; combined, these mice offer an opportunity to examine the requirement for activated BMP signaling on the anabolic and fracture healing activity of Wnts. When Dkk1+/− mice were crossed with Bmp2c/c;Prx1::cre mice, the offspring bearing both genetic alterations were unable to increase bone mass and heal fractures, indicating that increased canonical Wnt signaling is unable to exploit its activity in absence of Bmp2. Thus, our data suggest that BMP signaling is required for Wnt-mediated anabolic activity and that therapies aimed at preventing fractures and fostering fracture repair may need to target both pathways for maximal efficacy. PMID:25603465

  20. BMP2 and BMP7 play antagonistic roles in feather induction

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    Michon, Frédéric; Forest, Loïc; Collomb, Elodie; Demongeot, Jacques; Dhouailly, Danielle

    2008-01-01

    Summary During embryonic development, feathers first appear as primordia consisting of an epidermal placode associated with a dermal condensation. In most previous studies, the BMPs have been proposed to function as inhibitors of the formation of cutaneous appendages. We showed that the function of BMPs is quite nuanced: BMP-2 and BMP-7, which are expressed in both skin components, act antagonistically and yet are both involved in the dermal condensations formation. BMP-7, the first to be expressed, is implicated in chemotaxis which leads to cell recruitment to the condensation, whereas BMP-2, which is expressed later, leads to an arrest of cell migration, likely via its modulation of EIIIA Fibronectin domain and α4-Integrin expression. We also propose a mathematical model, a reaction-diffusion system, based on cell proliferation, chemotaxis and the timing of BMP-2 and BMP-7 expression, which simulates the endogenous situation and reproduces the negative effects of excess BMP-2 or BMP-7 on feather patterning. PMID:18635609

  1. Enhanced osteogenesis of adipose derived stem cells with Noggin suppression and delivery of BMP-2.

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    Jiabing Fan

    Full Text Available Bone morphogenetic proteins (BMPs are believed to be the most potent osteoinductive factors. However, BMPs are highly pleiotropic molecules and their supra-physiological high dose requirement leads to adverse side effects and inefficient bone formation. Thus, there is a need to develop alternative osteoinductive growth factor strategies that can effectively complement BMP activity. In this study, we intrinsically stimulated BMP signaling in adipose derived stem cells (ASCs by downregulating noggin, a potent BMP antagonist, using an RNAi strategy. ASCs transduced with noggin shRNA significantly enhanced osteogenic differentiation of cells. The potency of endogenous BMPs was subsequently enhanced by stimulating ASCs with exogenous BMPs at a significantly reduced dose. The level of mineralization in noggin shRNA treated ASCs when treated with BMP-2 was comparable to that of control shRNA treated cell treated with 10-fold more BMP-2. The complementary strategy of noggin suppression + BMP-2 to enhance osteogenesis was further confirmed in 3D in vitro environments using scaffolds consisting of chitosan (CH, chondroitin sulfate (CS, and apatite layer on their surfaces designed to slowly release BMP-2. This finding supports the novel therapeutic potential of this complementary strategy in bone regeneration.

  2. Bone marrow concentrate promotes bone regeneration with a suboptimal-dose of rhBMP-2.

    Science.gov (United States)

    Egashira, Kazuhiro; Sumita, Yoshinori; Zhong, Weijian; I, Takashi; Ohba, Seigo; Nagai, Kazuhiro; Asahina, Izumi

    2018-01-01

    Bone marrow concentrate (BMC), which is enriched in mononuclear cells (MNCs) and platelets, has recently attracted the attention of clinicians as a new optional means for bone engineering. We previously reported that the osteoinductive effect of bone morphogenetic protein-2 (BMP-2) could be enhanced synergistically by co-transplantation of peripheral blood (PB)-derived platelet-rich plasma (PRP). This study aims to investigate whether BMC can effectively promote bone formation induced by low-dose BMP-2, thereby reducing the undesirable side-effects of BMP-2, compared to PRP. Human BMC was obtained from bone marrow aspirates using an automated blood separator. The BMC was then seeded onto β-TCP granules pre-adsorbed with a suboptimal-dose (minimum concentration to induce bone formation at 2 weeks in mice) of recombinant human (rh) BMP-2. These specimens were transplanted subcutaneously to the dorsal skin of immunodeficient-mice and the induction of ectopic bone formation was assessed 2 and 4 weeks post-transplantation. Transplantations of five other groups [PB, PRP, platelet-poor plasma (PPP), bone marrow aspirate (BM), and BM-PPP] were employed as experimental controls. Then, to clarify the effects on vertical bone augmentation, specimens from the six groups were transplanted for on-lay placement on the craniums of mice. The results indicated that BMC, which contained an approximately 2.5-fold increase in the number of MNCs compared to PRP, could accelerate ectopic bone formation until 2 weeks post-transplantation. On the cranium, the BMC group promoted bone augmentation with a suboptimal-dose of rhBMP-2 compared to other groups. Particularly in the BMC specimens harvested at 4 weeks, we observed newly formed bone surrounding the TCP granules at sites far from the calvarial bone. In conclusion, the addition of BMC could reduce the amount of rhBMP-2 by one-half via its synergistic effect on early-phase osteoinduction. We propose here that BMC transplantation

  3. Mesenchymal stem cells with rhBMP-2 inhibits the growth of canine osteosarcoma cells

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    Grassi Rici Rose

    2012-02-01

    Full Text Available Abstract Background The bone morphogenetic proteins (BMPs belong to a unique group of proteins that includes the growth factor TGF-β. BMPs play important roles in cell differentiation, cell proliferation, and inhibition of cell growth. They also participate in the maturation of several cell types, depending on the microenvironment and interactions with other regulatory factors. Depending on their concentration gradient, the BMPs can attract various types of cells and act as chemotactic, mitogenic, or differentiation agents. BMPs can interfere with cell proliferation and the formation of cartilage and bone. In addition, BMPs can induce the differentiation of mesenchymal progenitor cells into various cell types, including chondroblasts and osteoblasts. The aim of this study was to analyze the effects of treatment with rhBMP-2 on the proliferation of canine mesenchymal stem cells (cMSCs and the tumor suppression properties of rhBMP-2 in canine osteocarcoma (OST cells. Osteosarcoma cell lines were isolated from biopsies and excisions of animals with osteosarcoma and were characterized by the Laboratory of Biochemistry and Biophysics, Butantan Institute. The mesenchymal stem cells were derived from the bone marrow of canine fetuses (cMSCs and belong to the University of São Paulo, College of Veterinary Medicine (FMVZ-USP stem cell bank. After expansion, the cells were cultured in a 12-well Transwell system; cells were treated with bone marrow mesenchymal stem cells associated with rhBMP2. Expression of the intracytoplasmic and nuclear markers such as Caspase-3, Bax, Bad, Bcl-2, Ki-67, p53, Oct3/4, Nanog, Stro-1 were performed by flow citometry. Results We evaluated the regenerative potential of in vitro treatment with rhBMP-2 and found that both osteogenic induction and tumor regression occur in stem cells from canine bone marrow. rhBMP-2 inhibits the proliferation capacity of OST cells by mechanisms of apoptosis and tumor suppression mediated by p

  4. Mesenchymal stem cells with rhBMP-2 inhibits the growth of canine osteosarcoma cells.

    Science.gov (United States)

    Rici, Rose Eli Grassi; Alcântara, Dayane; Fratini, Paula; Wenceslau, Cristiane Valverde; Ambrósio, Carlos Eduardo; Miglino, Maria Angelica; Maria, Durvanei Augusto

    2012-02-22

    The bone morphogenetic proteins (BMPs) belong to a unique group of proteins that includes the growth factor TGF-β. BMPs play important roles in cell differentiation, cell proliferation, and inhibition of cell growth. They also participate in the maturation of several cell types, depending on the microenvironment and interactions with other regulatory factors. Depending on their concentration gradient, the BMPs can attract various types of cells and act as chemotactic, mitogenic, or differentiation agents. BMPs can interfere with cell proliferation and the formation of cartilage and bone. In addition, BMPs can induce the differentiation of mesenchymal progenitor cells into various cell types, including chondroblasts and osteoblasts. The aim of this study was to analyze the effects of treatment with rhBMP-2 on the proliferation of canine mesenchymal stem cells (cMSCs) and the tumor suppression properties of rhBMP-2 in canine osteocarcoma (OST) cells. Osteosarcoma cell lines were isolated from biopsies and excisions of animals with osteosarcoma and were characterized by the Laboratory of Biochemistry and Biophysics, Butantan Institute. The mesenchymal stem cells were derived from the bone marrow of canine fetuses (cMSCs) and belong to the University of São Paulo, College of Veterinary Medicine (FMVZ-USP) stem cell bank. After expansion, the cells were cultured in a 12-well Transwell system; cells were treated with bone marrow mesenchymal stem cells associated with rhBMP2. Expression of the intracytoplasmic and nuclear markers such as Caspase-3, Bax, Bad, Bcl-2, Ki-67, p53, Oct3/4, Nanog, Stro-1 were performed by flow citometry. We evaluated the regenerative potential of in vitro treatment with rhBMP-2 and found that both osteogenic induction and tumor regression occur in stem cells from canine bone marrow. rhBMP-2 inhibits the proliferation capacity of OST cells by mechanisms of apoptosis and tumor suppression mediated by p53. We propose that rhBMP-2 has great

  5. Cyst-Like Osteolytic Formations in Recombinant Human Bone Morphogenetic Protein-2 (rhBMP-2) Augmented Sheep Spinal Fusion.

    Science.gov (United States)

    Pan, Hsin Chuan; Lee, Soonchul; Ting, Kang; Shen, Jia; Wang, Chenchao; Nguyen, Alan; Berthiaume, Emily A; Zara, Janette N; Turner, A Simon; Seim, Howard B; Kwak, Jin Hee; Zhang, Xinli; Soo, Chia

    2017-07-01

    Multiple case reports using recombinant human bone morphogenetic protein-2 (rhBMP-2) have reported complications. However, the local adverse effects of rhBMP-2 application are not well documented. In this report we show that, in addition to promoting lumbar spinal fusion through potent osteogenic effects, rhBMP-2 augmentation promotes local cyst-like osteolytic formations in sheep trabecular bones that have undergone anterior lumbar interbody fusion. Three months after operation, conventional computed tomography showed that the trabecular bones of the rhBMP-2 application groups could fuse, whereas no fusion was observed in the control group. Micro-computed tomography analysis revealed that the core implant area's bone volume fraction and bone mineral density increased proportionately with rhBMP-2 dose. Multiple cyst-like bone voids were observed in peri-implant areas when using rhBMP-2 applications, and these sites showed significant bone mineral density decreases in relation to the unaffected regions. Biomechanically, these areas decreased in strength by 32% in comparison with noncystic areas. Histologically, rhBMP-2-affected void sites had an increased amount of fatty marrow, thinner trabecular bones, and significantly more adiponectin- and cathepsin K-positive cells. Despite promoting successful fusion, rhBMP-2 use in clinical applications may result in local adverse structural alterations and compromised biomechanical changes to the bone. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  6. Bone morphogenetic protein 2 (BMP2) induces growth suppression and enhances chemosensitivity of human colon cancer cells

    DEFF Research Database (Denmark)

    Vishnubalaji, Radhakrishnan; Yue, Shijun; Alfayez, Musaad

    2016-01-01

    expression were assessed using qRT-PCR. AlamarBlue assay was used to assess cell viability in vitro. In vivo experiments were conducted using SCID mice. RESULTS: Our data revealed frequent downregulation of BMP2 in primary CRC tissues. Additionally, interrogation of publically available gene expression......, suggesting that restoration of BMP2 expression could be a potential therapeutic strategy for CRC....

  7. Deficiency of retinaldehyde dehydrogenase 1 induces BMP2 and increases bone mass in vivo.

    Directory of Open Access Journals (Sweden)

    Shriram Nallamshetty

    Full Text Available The effects of retinoids, the structural derivatives of vitamin A (retinol, on post-natal peak bone density acquisition and skeletal remodeling are complex and compartment specific. Emerging data indicates that retinoids, such as all trans retinoic acid (ATRA and its precursor all trans retinaldehyde (Rald, exhibit distinct and divergent transcriptional effects in metabolism. Despite these observations, the role of enzymes that control retinoid metabolism in bone remains undefined. In this study, we examined the skeletal phenotype of mice deficient in retinaldehyde dehydrogenase 1 (Aldh1a1, the enzyme responsible for converting Rald to ATRA in adult animals. Bone densitometry and micro-computed tomography (µCT demonstrated that Aldh1a1-deficient (Aldh1a1(-/- female mice had higher trabecular and cortical bone mass compared to age and sex-matched control C57Bl/6 wild type (WT mice at multiple time points. Histomorphometry confirmed increased cortical bone thickness and demonstrated significantly higher bone marrow adiposity in Aldh1a1(-/- mice. In serum assays, Aldh1a1(-/- mice also had higher serum IGF-1 levels. In vitro, primary Aldh1a1(-/- mesenchymal stem cells (MSCs expressed significantly higher levels of bone morphogenetic protein 2 (BMP2 and demonstrated enhanced osteoblastogenesis and adipogenesis versus WT MSCs. BMP2 was also expressed at higher levels in the femurs and tibias of Aldh1a1(-/- mice with accompanying induction of BMP2-regulated responses, including expression of Runx2 and alkaline phosphatase, and Smad phosphorylation. In vitro, Rald, which accumulates in Aldh1a1(-/- mice, potently induced BMP2 in WT MSCs in a retinoic acid receptor (RAR-dependent manner, suggesting that Rald is involved in the BMP2 increases seen in Aldh1a1 deficiency in vivo. Collectively, these data implicate Aldh1a1 as a novel determinant of cortical bone density and marrow adiposity in the skeleton in vivo through modulation of BMP signaling.

  8. Deficiency of retinaldehyde dehydrogenase 1 induces BMP2 and increases bone mass in vivo.

    Science.gov (United States)

    Nallamshetty, Shriram; Wang, Hong; Rhee, Eun-Jung; Kiefer, Florian W; Brown, Jonathan D; Lotinun, Sutada; Le, Phuong; Baron, Roland; Rosen, Clifford J; Plutzky, Jorge

    2013-01-01

    The effects of retinoids, the structural derivatives of vitamin A (retinol), on post-natal peak bone density acquisition and skeletal remodeling are complex and compartment specific. Emerging data indicates that retinoids, such as all trans retinoic acid (ATRA) and its precursor all trans retinaldehyde (Rald), exhibit distinct and divergent transcriptional effects in metabolism. Despite these observations, the role of enzymes that control retinoid metabolism in bone remains undefined. In this study, we examined the skeletal phenotype of mice deficient in retinaldehyde dehydrogenase 1 (Aldh1a1), the enzyme responsible for converting Rald to ATRA in adult animals. Bone densitometry and micro-computed tomography (µCT) demonstrated that Aldh1a1-deficient (Aldh1a1(-/-) ) female mice had higher trabecular and cortical bone mass compared to age and sex-matched control C57Bl/6 wild type (WT) mice at multiple time points. Histomorphometry confirmed increased cortical bone thickness and demonstrated significantly higher bone marrow adiposity in Aldh1a1(-/-) mice. In serum assays, Aldh1a1(-/-) mice also had higher serum IGF-1 levels. In vitro, primary Aldh1a1(-/-) mesenchymal stem cells (MSCs) expressed significantly higher levels of bone morphogenetic protein 2 (BMP2) and demonstrated enhanced osteoblastogenesis and adipogenesis versus WT MSCs. BMP2 was also expressed at higher levels in the femurs and tibias of Aldh1a1(-/-) mice with accompanying induction of BMP2-regulated responses, including expression of Runx2 and alkaline phosphatase, and Smad phosphorylation. In vitro, Rald, which accumulates in Aldh1a1(-/-) mice, potently induced BMP2 in WT MSCs in a retinoic acid receptor (RAR)-dependent manner, suggesting that Rald is involved in the BMP2 increases seen in Aldh1a1 deficiency in vivo. Collectively, these data implicate Aldh1a1 as a novel determinant of cortical bone density and marrow adiposity in the skeleton in vivo through modulation of BMP signaling.

  9. Building the Future: Post-transcriptional Regulation of Cell Fate Decisions Prior to the Xenopus Midblastula Transition.

    Science.gov (United States)

    Sheets, Michael D

    2015-01-01

    In all animals, a critical period in early development is when embryonic cells switch from relying solely upon maternally deposited RNAs and proteins to relying upon molecules encoded by the zygotic genome. Xenopus embryos have served as a model for examining this switch, as well as the maternally controlled stages that prepare for it. In Xenopus, the robust activation of zygotic transcription occurs at the 12th cleavage division and is referred to as the midblastula transition (MBT). Prior to MBT, gene expression is regulated by post-transcriptional events including mRNA and protein localization, protein post-translational modification, and mRNA translation. After the MBT, appropriate transcriptional regulation of the zygotic genome becomes critical and predominates. However, it is important to realize that the first key cell fate decisions that have profound impacts on development occur prior to the MBT and these are governed by regulating the expression of maternally deposited regulatory mRNAs and proteins. In this chapter, I will discuss post-transcriptional mechanisms that function during the maternal stages of Xenopus development with an emphasis on mechanisms known to directly modulate cell fate decisions. Emerging approaches and technologies that will help better understand this phase of development will also be discussed. © 2015 Elsevier Inc. All rights reserved.

  10. Multiple post-transcriptional regulatory mechanisms in ferritin gene expression

    International Nuclear Information System (INIS)

    Mattia, E.; Den Blaauwen, J.; Van Renswoude, J.; Ashwell, G.

    1989-01-01

    The authors have investigated the mechanisms involved in the regulation of ferritin biosynthesis in K562 human erythroleukemia cells during prolonged exposure to iron. They show that, upon addition of hemin (an efficient iron donor) to the cell culture, the rate of ferritin biosynthesis reaches a maximum after a few hours and then decreases. During a 24-hr incubation with the iron donor the concentrations of total ferritin heavy (H) and light (L) subunit mRNAs rise 2- to 5-fold and 2- to 3-fold, respectively, over the control values, while the amount of the protein increases 10- to 30-fold. The hemin-induced increment in ferritin subunit mRNA is not prevented by deferoxamine, suggesting that it is not directly mediated by chelatable iron. In vitro nuclear transcription analyses performed on nuclei isolated from control cells and cells grown in the presence of hemin indicate that the rates of synthesis of H- and L-subunit mRNAs remain constant. They conclude that iron-induced ferritin biosynthesis is governed by multiple post-transcriptional regulatory mechanisms. They propose that exposure of cells to iron leads to stabilization of ferritin mRNAs, in addition to activation and translation of stored H-and L-subunit mRNAs

  11. DMPD: Post-transcriptional regulation of proinflammatory proteins. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 15075353 Post-transcriptional regulation of proinflammatory proteins. Anderson P, P...l) (.csml) Show Post-transcriptional regulation of proinflammatory proteins. PubmedID 15075353 Title Post-tr...anscriptional regulation of proinflammatory proteins. Authors Anderson P, Phillip

  12. Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Chieri [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan); Iwasaki, Tsuyoshi, E-mail: tsuyo-i@huhs.ac.jp [Division of Pharmacotherapy, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe 650-8530 (Japan); Kitano, Sachie; Tsunemi, Sachi; Sano, Hajime [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan)

    2012-06-22

    Highlights: Black-Right-Pointing-Pointer We investigated the role of S1P signaling for osteoblast differentiation. Black-Right-Pointing-Pointer Both S1P and FTY enhanced BMP-2-stimulated osteoblast differentiation by C2C12 cells. Black-Right-Pointing-Pointer S1P signaling enhanced BMP-2-stimulated Smad and ERK phosphorylation by C2C12 cells. Black-Right-Pointing-Pointer MEK/ERK signaling is a pathway underlying S1P signaling for osteoblast differentiation. -- Abstract: We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P

  13. Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation

    International Nuclear Information System (INIS)

    Sato, Chieri; Iwasaki, Tsuyoshi; Kitano, Sachie; Tsunemi, Sachi; Sano, Hajime

    2012-01-01

    Highlights: ► We investigated the role of S1P signaling for osteoblast differentiation. ► Both S1P and FTY enhanced BMP-2-stimulated osteoblast differentiation by C2C12 cells. ► S1P signaling enhanced BMP-2-stimulated Smad and ERK phosphorylation by C2C12 cells. ► MEK/ERK signaling is a pathway underlying S1P signaling for osteoblast differentiation. -- Abstract: We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P receptor-mediated signaling plays a crucial role for osteoblast differentiation.

  14. rhBMP-2 (ACS and CRM formulations) overcomes pseudarthrosis in a New Zealand white rabbit posterolateral fusion model.

    Science.gov (United States)

    Lawrence, James P; Waked, Walid; Gillon, Thomas J; White, Andrew P; Spock, Christopher R; Biswas, Debdut; Rosenberger, Patricia; Troiano, Nancy; Albert, Todd J; Grauer, Jonathan N

    2007-05-15

    The study design consisted of a New Zealand white rabbit model of pseudarthrosis repair. Study groups consisting of no graft, autograft, or recombinant human bone morphogenetic protein-2 (rhBMP-2) with absorbable collagen sponge (ACS) or compression resistant matrix (CRM) were evaluated. To evaluate the relative efficacy of bone graft materials (autograft, ACS, and CRM). rhBMP-2 has been shown to have a 100% fusion rate in a primary rabbit fusion model, even in the presence of nicotine, which is known to inhibit fusion. Seventy-two New Zealand white rabbits underwent posterolateral lumbar fusion with iliac crest autograft. To establish pseudarthroses, nicotine was administered to all animals. At 5 weeks, the spines were explored and all pseudarthroses were redecorticated and implanted with no graft, autograft, rhBMP-2/ACS, or rhBMP-2/CRM. At 10 weeks, fusions were assessed by manual palpation and histology. Eight rabbits (11%) were lost to complications. At 5 weeks, 66 (97%) had pseudarthroses. At 10 weeks, attempted pseudarthrosis repairs were fused in 1 of 16 of no graft rabbits (6%), 5 of 17 autograft rabbits (29%), and 31 of 31 rhBMP-2 rabbits (with ACS or CRM) (100%). Histologic analysis demonstrated more mature bone formation in the rhBMP-2 groups. The 2 rhBMP-2 formulations led to significantly higher fusion rates and histologic bone formation than no graft and autograft controls in this pseudarthrosis repair model.

  15. Electrospun PLLA nanofiber scaffolds and their use in combination with BMP-2 for reconstruction of bone defects.

    Directory of Open Access Journals (Sweden)

    Markus D Schofer

    Full Text Available Adequate migration and differentiation of mesenchymal stem cells is essential for regeneration of large bone defects. To achieve this, modern graft materials are becoming increasingly important. Among them, electrospun nanofiber scaffolds are a promising approach, because of their high physical porosity and potential to mimic the extracellular matrix (ECM.The objective of the present study was to examine the impact of electrospun PLLA nanofiber scaffolds on bone formation in vivo, using a critical size rat calvarial defect model. In addition we analyzed whether direct incorporation of bone morphogenetic protein 2 (BMP-2 into nanofibers could enhance the osteoinductivity of the scaffolds. Two critical size calvarial defects (5 mm were created in the parietal bones of adult male Sprague-Dawley rats. Defects were either (1 left unfilled, or treated with (2 bovine spongiosa, (3 PLLA scaffolds alone or (4 PLLA/BMP-2 scaffolds. Cranial CT-scans were taken at fixed intervals in vivo. Specimens obtained after euthanasia were processed for histology, histomorphometry and immunostaining (Osteocalcin, BMP-2 and Smad5.PLLA scaffolds were well colonized with cells after implantation, but only showed marginal ossification. PLLA/BMP-2 scaffolds showed much better bone regeneration and several ossification foci were observed throughout the defect. PLLA/BMP-2 scaffolds also stimulated significantly faster bone regeneration during the first eight weeks compared to bovine spongiosa. However, no significant differences between these two scaffolds could be observed after twelve weeks. Expression of osteogenic marker proteins in PLLA/BMP-2 scaffolds continuously increased throughout the observation period. After twelve weeks osteocalcin, BMP-2 and Smad5 were all significantly higher in the PLLA/BMP-2 group than in all other groups.Electrospun PLLA nanofibers facilitate colonization of bone defects, while their use in combination with BMP-2 also increases bone

  16. Stimulation of porcine bone marrow stromal cells by hyaluronan, dexamethasone and rhBMP-2

    DEFF Research Database (Denmark)

    Zou, Xuenong; Li, Haisheng; Chen, Li

    2004-01-01

    and 7. When BMSc were cultivated with HY of 4.0 mg/ml alone, its combinations with Dex (+) and 10 ng/ml rhBMP-2, and with DMEM/FBS alone, expression of bone-related marker genes was evaluated by real-time reverse transcription-polymerase chain reaction (Real-time RT-PCR) analysis. Osteocalcin was up...... collagen and type X collagen were down-regulated in the presence of 4 mg/ml HY by Day 7. These results suggest that HY stimulates BMSc proliferation, osteocalcin gene expression, and a secretion of enzymes such as that of ALP activity in vitro. More importantly, HY can interact with Dex and rhBMP-2...

  17. Enhanced Bone Formation in Segmental Defects with BMP2 in a Biologically Relevant Molecular Context

    Science.gov (United States)

    2016-10-16

    interfere with the biological activity of the BMP2, and because radioisotope detection methods are highly sensitive and remain quantitative across a large...PRINCIPAL INVESTIGATOR: Dominik R. Haudenschild CONTRACTING ORGANIZATION: University of California, Davis Davis, CA 95618 REPORT DATE : October 2016...control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE October 2016 2. REPORT TYPE Annual 3. DATES COVERED 30 Sep 2015

  18. Bone regeneration in osteoporosis by delivery BMP-2 and PRGF from tetronic-alginate composite thermogel.

    Science.gov (United States)

    Segredo-Morales, Elisabet; García-García, Patricia; Reyes, Ricardo; Pérez-Herrero, Edgar; Delgado, Araceli; Évora, Carmen

    2018-05-30

    As the life expectancy of the world population increases, osteoporotic (OP) fracture risk increase. Therefore in the present study a novel injectable thermo-responsive hydrogel loaded with microspheres of 17β-estradiol, microspheres of bone morphogenetic protein-2 (BMP-2) and plasma rich in growth factors (PRGF) was applied locally to regenerate a calvaria critical bone defect in OP female rats. Three systems were characterized: Tetronic® 1307 (T-1307) reinforced with alginate (T-A), T-A with PRGF and T-A-PRGF with microspheres. The addition of the microspheres increased the viscosity but the temperature for the maximum viscosity did not change (22-24 °C). The drugs were released during 6 weeks in one fast phase (three days) followed by a long slow phase. In vivo evaluation was made in non-OP and OP rats treated with T-A, T-A with microspheres of 17β-estradiol (T-A-βE), T-A-βE prepared with PRGF (T-A-PRGF-βE), T-A-βE with microspheres of BMP-2 (T-A-βE-BMP-2) and the combination of the three (T-A-PRGF-βE-BMP). After 12 weeks, histological and histomorphometric analyzes showed a synergic effect due to the addition of BMP-2 to the T-A-βE formulation. The PRGF did not increased the bone repair. The new bone filling the OP defect was less mineralized than in the non-OP groups. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. [Preparation of vanilline cross-linked rhBMP-2/chitosan microspheres and its effect on mesenchymal stem cells].

    Science.gov (United States)

    Wu, Gui; Wang, Hai; Qiu, Guixing; Yu, Xin; Su, Xinlin; Ma, Pei; Yin, Bo; Wu, Zhihong

    2015-06-02

    To prepare rhBMP-2/chitosan microspheres (rhBMP-2 CMs) with vanilline as a cross-linking reagent and study the biocompatibility and drug release characteristic of microspheres in vitro. Emulsion cross-linking method was utilized to prepare rhBMP-2 CMs, Scanning electron microscope (SEM) was used to observe the microstructure of microspheres.Leaching solution of microspheres and blank culture medium were designated as experimental and control groups respectively. Both groups were cultured with human mesenchymal stem cells (hMSCs) to determine its cytotoxicity and its effect on the proliferation of hMSCs. Dynamic immersion method was used to examine the in vitro release characteristic of rhBMP-2. And the alkaline phosphatase (ALP) activity of hMSCs was determined to reveal the bioactivity of released rhBMP-2. The rhBMP-2 CMs were spherical under SEM.After treating with leaching solution for 24 and 48 h, there was no inter-group statistical difference in optical density (OD) values at both timepoints (24 h:0.72 ± 0.07 vs 0.73 ± 0.05, P > 0.05; 48 h:1.19 ± 0.11 vs 1.27 ± 0.06, P > 0.05). After culturing with leaching solution for 1, 3 and 7 days, the number of cells increased with time for both groups. And the OD values were not statistically different at each timepoint. Five milligram rhBMP-2 CMs soaked for 19 days with a gradual release of rhBMP-2. The concentration of rhBMP-2 was 216.1 ± 20.0 ng/ml at Day 19. At Days 3 and 7, the ALP activities of hMSCs were (0.50 ± 0.07) and (0.68 ± 0.06) µmol pNPP·min⁻¹·mg⁻¹ protein respectively and both were higher than that of blank culture medium group (0.14 ± 0.01) (P < 0.05). With an excellent biocompatibility, rhBMP-2 CMs may be an ideal carrier for control-released rhBMP-2 and encapsulated rhBMP-2 remains bioactive.

  20. Kaempferol induces chondrogenesis in ATDC5 cells through activation of ERK/BMP-2 signaling pathway.

    Science.gov (United States)

    Nepal, Manoj; Li, Liang; Cho, Hyoung Kwon; Park, Jong Kun; Soh, Yunjo

    2013-12-01

    Endochondral bone formation occurs when mesenchymal cells condense to differentiate into chondrocytes, the primary cell types of cartilage. The aim of the present study was to identify novel factors regulating chondrogenesis. We investigated whether kaempferol induces chondrogenic differentiation in clonal mouse chondrogenic ATDC5 cells. Kaempferol treatment stimulated the accumulation of cartilage nodules in a dose-dependent manner. Kaempferol-treated ATDC5 cells stained more intensely with alcian blue staining than control cells, suggesting greater synthesis of matrix proteoglycans in the kaempferol-treated cells. Similarly, kaempferol induced greater activation of alkaline phosphatase activity than control cells, and it enhanced the expression of chondrogenic marker genes, such as collagen type I, collagen type X, OCN, Runx2, and Sox9. Kaempferol induced an acute activation of extracellular signal-regulated kinase (ERK) but not c-jun N-terminal kinase or p38 MAP kinase. PD98059, an inhibitor of MAPK/ERK, decreased in stained cells treated with kaempferol. Furthermore, kaempferol greatly expressed the protein and mRNA levels of BMP-2, suggesting chondrogenesis was stimulated via a BMP-2 pathway. Taken together, our results suggest that kaempferol has chondromodulating effects via an ERK/BMP-2 signaling pathway and could potentially be used as a therapeutic agent for bone growth disorders. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. RNA-binding proteins involved in post-transcriptional regulation in bacteria

    Directory of Open Access Journals (Sweden)

    Elke eVan Assche

    2015-03-01

    Full Text Available Post-transcriptional regulation is a very important mechanism to control gene expression in changing environments. In the past decade, a lot of interest has been directed towards the role of small RNAs in bacterial post-transcriptional regulation. However, small RNAs are not the only molecules controlling gene expression at this level, RNA-binding proteins play an important role as well. CsrA and Hfq are the two best studied bacterial proteins of this type, but recently, additional proteins involved in post-transcriptional control have been identified. This review focuses on the general working mechanisms of post-transcriptionally active RNA-binding proteins, which include (i adaptation of the susceptibility of mRNAs and sRNAs to RNases, (ii modulating the accessibility of the ribosome binding site of mRNAs, (iii recruiting and assisting in the interaction of mRNAs with other molecules and (iv regulating transcription terminator / antiterminator formation, and gives an overview of both the well-studied and the newly identified proteins that are involved in post-transcriptional regulatory processes. Additionally, the post-transcriptional mechanisms by which the expression or the activity of these proteins is regulated, are described. For many of the newly identified proteins, however, mechanistic questions remain. Most likely, more post-transcriptionally active proteins will be identified in the future.

  2. Trends Analysis of rhBMP2 Utilization in Single-Level Anterior Lumbar Interbody Fusion in the United States.

    Science.gov (United States)

    Lao, Lifeng; Cohen, Jeremiah R; Buser, Zorica; Brodke, Darrel S; Yoon, S Tim; Youssef, Jim A; Park, Jong-Beom; Meisel, Hans-Joerg; Wang, Jeffrey C

    2018-04-01

    Retrospective case study. To evaluate the trends and demographics of recombinant human bone morphogenetic protein 2 (rhBMP2) utilization in single-level anterior lumbar interbody fusion (ALIF) in the United States. Patients who underwent single-level ALIF from 2005 to 2011 were identified by searching ICD-9 diagnosis and procedure codes in the PearlDiver Patient Records Database (PearlDiver Technologies, Fort Wayne, IN), a national database of orthopedic insurance records. The year of procedure, age, gender, and region of the United States were analyzed for each patient. A total of 921 patients were identified who underwent a single-level ALIF in this study. The average rate of single-level ALIF with rhBMP2 utilization increased (35%-48%) from 2005 to 2009, but sharply decreased to 16.7% in 2010 and 15.0% in 2011. The overall incidence of single-level ALIF without rhBMP2 (0.20 cases per 100 000 patients) was more than twice of the incidence of single-level ALIF with rhBMP2 (0.09 cases per 100 000 patients). The average rate of single-level ALIF with rhBMP2 utilization is highest in West (41.4%), followed by Midwest (33.3%), South (26.5%) and Northeast (22.2%). The highest incidence of single-level ALIF with rhBMP2 was observed in the group aged less than 65 years (compared with any other age groups, P level ALIF increased from 2006 to 2009, but decreased in 2010 and 2011. The Northeast region had the lowest incidence of rhBMP2 utilization. The group aged less than 65 years trended to have the higher incidence of single-level ALIF with rhBMP2 utilization.

  3. Expression characteristics of BMP2, BMPR-IA and Noggin in different stages of hair follicle in yak skin.

    Science.gov (United States)

    Song, Liang-Li; Cui, Yan; Yu, Si-Jiu; Liu, Peng-Gang; Liu, Jun; Yang, Xue; He, Jun-Feng; Zhang, Qian

    2018-05-01

    Bone morphogenetic protein 2 (BMP2), BMP receptor-IA (BMPR-IA), and the BMP2 antagonist Noggin are important proteins involved in regulating the hair follicle (HF) cycle in skin. In order to explore the expression profiles of BMP2, BMPR-IA, and Noggin in the HF cycle of yak skin, we collected adult yak skin in the telogen, proanagen, and midanagen phases of HFs and evaluated gene and protein expression by real-time quantitative polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry. qRT-PCR and western blotting results showed that BMP2 and BMPR-IA expression levels were highest in the telogen of HFs and higher than that of Noggin in the same phase. The expression of Noggin was significantly higher in proanagen and midanagen phases of HFs than in the telogen phase, with the highest expression observed in the proanagen phase. Moreover, the expression of Noggin in the proanagen phase was significantly higher than those of BMP2 and BMPR-IA during the same phase. Immunohistochemistry results showed that BMP2, BMPR-IA, and Noggin were expressed in the skin epidermis, sweat glands, sebaceous glands, HF outer root sheath, and hair matrix. In summary, the characteristic expression profiles of BMP2, BMPR-IA, and Noggin suggested that BMP2 and BMPR-IA had inhibitory effects on the growth of HFs in yaks, whereas Noggin promoted the growth of yak HFs, mainly by affecting skin epithelial cell activity. These results provide a basis for further studies of HF development and cycle transition in yak skin. Copyright © 2017. Published by Elsevier Inc.

  4. Myoblast sensitivity and fibroblast insensitivity to osteogenic conversion by BMP-2 correlates with the expression of Bmpr-1a

    Directory of Open Access Journals (Sweden)

    North Kathryn N

    2009-05-01

    Full Text Available Abstract Background Osteoblasts are considered to primarily arise from osseous progenitors within the periosteum or bone marrow. We have speculated that cells from local soft tissues may also take on an osteogenic phenotype. Myoblasts are known to adopt a bone gene program upon treatment with the osteogenic bone morphogenetic proteins (BMP-2,-4,-6,-7,-9, but their osteogenic capacity relative to other progenitor types is unclear. We further hypothesized that the sensitivity of cells to BMP-2 would correlate with BMP receptor expression. Methods We directly compared the BMP-2 sensitivity of myoblastic murine cell lines and primary cells with osteoprogenitors from osseous tissues and fibroblasts. Fibroblasts forced to undergo myogenic conversion by transduction with a MyoD-expressing lentiviral vector (LV-MyoD were also examined. Outcome measures included alkaline phosphatase expression, matrix mineralization, and expression of osteogenic genes (alkaline phosphatase, osteocalcin and bone morphogenetic protein receptor-1A as measured by quantitative PCR. Results BMP-2 induced a rapid and robust osteogenic response in myoblasts and osteoprogenitors, but not in fibroblasts. Myoblasts and osteoprogenitors grown in osteogenic media rapidly upregulated Bmpr-1a expression. Chronic BMP-2 treatment resulted in peak Bmpr-1a expression at day 6 before declining, suggestive of a negative feedback mechanism. In contrast, fibroblasts expressed low levels of Bmpr-1a that was only weakly up-regulated by BMP-2 treatment. Bioinformatics analysis confirmed the presence of myogenic responsive elements in the proximal promoter region of human and murine BMPR-1A/Bmpr-1a. Forced myogenic gene expression in fibroblasts was associated with a significant increase in Bmpr-1a expression and a synergistic increase in the osteogenic response to BMP-2. Conclusion These data demonstrate the osteogenic sensitivity of muscle progenitors and provide a mechanistic insight into the

  5. Ectopic application of recombinant BMP-2 and BMP-4 can change patterning of developing chick facial primordia.

    Science.gov (United States)

    Barlow, A J; Francis-West, P H

    1997-01-01

    The facial primordia initially consist of buds of undifferentiated mesenchyme, which give rise to a variety of tissues including cartilage, muscle and nerve. These must be arranged in a precise spatial order for correct function. The signals that control facial outgrowth and patterning are largely unknown. The bone morphogenetic proteins Bmp-2 and Bmp-4 are expressed in discrete regions at the distal tips of the early facial primordia suggesting possible roles for BMP-2 and BMP-4 during chick facial development. We show that expression of Bmp-4 and Bmp-2 is correlated with the expression of Msx-1 and Msx-2 and that ectopic application of BMP-2 and BMP-4 can activate Msx-1 and Msx-2 gene expression in the developing facial primordia. We correlate this activation of gene expression with changes in skeletal development. For example, activation of Msx-1 gene expression across the distal tip of the mandibular primordium is associated with an extension of Fgf-4 expression in the epithelium and bifurcation of Meckel's cartilage. In the maxillary primordium, extension of the normal domain of Msx-1 gene expression is correlated with extended epithelial expression of shh and bifurcation of the palatine bone. We also show that application of BMP-2 can increase cell proliferation of the mandibular primordia. Our data suggest that BMP-2 and BMP-4 are part of a signalling cascade that controls outgrowth and patterning of the facial primordia.

  6. Plasma Treated High-Density Polyethylene (HDPE Medpor Implant Immobilized with rhBMP-2 for Improving the Bone Regeneration

    Directory of Open Access Journals (Sweden)

    Jin-Su Lim

    2014-01-01

    Full Text Available We investigate the bone generation capacity of recombinant human bone morphogenetic protein-2 (rhBMP-2 immobilized Medpor surface through acrylic acid plasma-polymerization. Plasma-polymerization was carried out at a 20 W at an acrylic acid flow rate of 7 sccm for 5 min. The plasma-polymerized Medpor surface showed hydrophilic properties and possessed a high density of carboxyl groups. The rhBMP-2 was immobilized with covalently attached carboxyl groups using 1-ethyl-3-(3-dimethylaminopropyl carbodiimide and N-hydroxysuccinimide. Carboxyl groups and rhBMP-2 immobilization on the Medpor surface were identified by Fourier transform infrared spectroscopy. The activity of Medpor with rhBMP-2 immobilized was examined using an alkaline phosphatase assay on MC3T3-E1 cultured Medpor. These results showed that the rhBMP-2 immobilized Medpor increased the level of MC3T3-E1 cell differentiation. These results demonstrated that plasma surface modification has the potential to immobilize rhBMP-2 on polymer implant such as Medpor and can be used for the binding of bioactive nanomolecules in bone tissue engineering.

  7. Bone marrow stromal cells with a combined expression of BMP-2 and VEGF-165 enhanced bone regeneration

    International Nuclear Information System (INIS)

    Xiao Caiwen; Zhou Huifang; Fu Yao; Gu Ping; Fan Xianqun; Liu Guangpeng; Zhang Peng; Hou Hongliang; Tang Tingting

    2011-01-01

    Bone graft substitutes with osteogenic factors alone often exhibit poor bone regeneration due to inadequate vascularization. Combined delivery of osteogenic and angiogenic factors from biodegradable scaffolds may enhance bone regeneration. We evaluated the effects of bone morphogenetic protein 2 (BMP2) and vascular endothelial growth factor (VEGF), combined with natural coral scaffolds, on the repair of critical-sized bone defects in rabbit orbits. In vitro expanded rabbit bone marrow stromal cells (BMSCs) were transfected with human BMP2 and VEGF165 genes. Target protein expression and osteogenic differentiation were confirmed after gene transduction. Rabbit orbital defects were treated with a coral scaffold loaded with BMP2-transduced and VEGF-transduced BMSCs, BMP2-expressing BMSCs, VEGF-expressing BMSCs, or BMSCs without gene transduction. Volume and density of regenerated bone were determined by micro-computed tomography at 4, 8, and 16 weeks after implantation. Neovascularity, new bone deposition rate, and new bone formation were measured by immunostaining, tetracycline and calcein labelling, and histomorphometric analysis at different time points. The results showed that VEGF increased blood vessel formation relative to groups without VEGF. Combined delivery of BMP2 and VEGF increased new bone deposition and formation, compared with any single factor. These findings indicate that mimicking the natural bone development process by combined BMP2 and VEGF delivery improves healing of critical-sized orbital defects in rabbits.

  8. Autologous implantation of BMP2-expressing dermal fibroblasts to improve bone mineral density and architecture in rabbit long bones.

    Science.gov (United States)

    Ishihara, Akikazu; Weisbrode, Steve E; Bertone, Alicia L

    2015-10-01

    Cell-mediated gene therapy may treat bone fragility disorders. Dermal fibroblasts (DFb) may be an alternative cell source to stem cells for orthopedic gene therapy because of their rapid cell yield and excellent plasticity with bone morphogenetic protein-2 (BMP2) gene transduction. Autologous DFb or BMP2-expressing autologous DFb were administered in twelve rabbits by two delivery routes; a transcortical intra-medullar infusion into tibiae and delayed intra-osseous injection into femoral drill defects. Both delivery methods of DFb-BMP2 resulted in a successful cell engraftment, increased bone volume, bone mineral density, improved trabecular bone microarchitecture, greater bone defect filling, external callus formation, and trabecular surface area, compared to non-transduced DFb or no cells. Cell engraftment within trabecular bone and bone marrow tissue was most efficiently achieved by intra-osseous injection of DFb-BMP2. Our results suggested that BMP2-expressing autologous DFb have enhanced efficiency of engraftment in target bones resulting in a measurable biologic response by the bone of improved bone mineral density and bone microarchitecture. These results support that autologous implantation of DFb-BMP2 warrants further study on animal models of bone fragility disorders, such as osteogenesis imperfecta and osteoporosis to potentially enhance bone quality, particularly along with other gene modification of these diseases. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  9. Enhanced Healing of Rat Calvarial Defects with MSCs Loaded on BMP-2 Releasing Chitosan/Alginate/Hydroxyapatite Scaffolds

    Science.gov (United States)

    He, Xiaoning; Liu, Yang; Yuan, Xue; Lu, Li

    2014-01-01

    In this study, we designed a chitosan/alginate/hydroxyapatite scaffold as a carrier for recombinant BMP-2 (CAH/B2), and evaluated the release kinetics of BMP-2. We evaluated the effect of the CAH/B2 scaffold on the viability and differentiation of bone marrow mesenchymal stem cells (MSCs) by scanning electron microscopy, MTS, ALP assay, alizarin-red staining and qRT-PCR. Moreover, MSCs were seeded on scaffolds and used in a 8 mm rat calvarial defect model. New bone formation was assessed by radiology, hematoxylin and eosin staining 12 weeks postoperatively. We found the release kinetics of BMP-2 from the CAH/B2 scaffold were delayed compared with those from collagen gel, which is widely used for BMP-2 delivery. The BMP-2 released from the scaffold increased MSC differentiation and did not show any cytotoxicity. MSCs exhibited greater ALP activity as well as stronger calcium mineral deposition, and the bone-related markers Col1α, osteopontin, and osteocalcin were upregulated. Analysis of in vivo bone formation showed that the CAH/B2 scaffold induced more bone formation than other groups. This study demonstrates that CAH/B2 scaffolds might be useful for delivering osteogenic BMP-2 protein and present a promising bone regeneration strategy. PMID:25084008

  10. BMP-2 functions independently of SHH signaling and triggers cell condensation and apoptosis in regenerating axolotl limbs

    Directory of Open Access Journals (Sweden)

    Finnson Kenneth

    2010-02-01

    Full Text Available Abstract Background Axolotls have the unique ability, among vertebrates, to perfectly regenerate complex body parts, such as limbs, after amputation. In addition, axolotls pattern developing and regenerating autopods from the anterior to posterior axis instead of posterior to anterior like all tetrapods studied to date. Sonic hedgehog is important in establishing this anterior-posterior axis of limbs in all tetrapods including axolotls. Interestingly, its expression is conserved (to the posterior side of limb buds and blastemas in axolotl limbs as in other tetrapods. It has been suggested that BMP-2 may be the secondary mediator of sonic hedgehog, although there is mounting evidence to the contrary in mice. Since BMP-2 expression is on the anterior portion of developing and regenerating limbs prior to digit patterning, opposite to the expression of sonic hedgehog, we examined whether BMP-2 expression was dependent on sonic hedgehog signaling and whether it affects patterning of the autopod during regeneration. Results The expression of BMP-2 and SOX-9 in developing and regenerating axolotl limbs corresponded to the first digits forming in the anterior portion of the autopods. The inhibition of sonic hedgehog signaling with cyclopamine caused hypomorphic limbs (during development and regeneration but did not affect the expression of BMP-2 and SOX-9. Overexpression of BMP-2 in regenerating limbs caused a loss of digits. Overexpression of Noggin (BMP inhibitor in regenerating limbs also resulted in a loss of digits. Histological analysis indicated that the loss due to BMP-2 overexpression was the result of increased cell condensation and apoptosis while the loss caused by Noggin was due to a decrease in cell division. Conclusion The expression of BMP-2 and its target SOX-9 was independent of sonic hedgehog signaling in developing and regenerating limbs. Their expression correlated with chondrogenesis and the appearance of skeletal elements has

  11. HIF-1α as a Regulator of BMP2-Induced Chondrogenic Differentiation, Osteogenic Differentiation, and Endochondral Ossification in Stem Cells

    Directory of Open Access Journals (Sweden)

    Nian Zhou

    2015-04-01

    Full Text Available Background/Aims: Joint cartilage defects are difficult to treat due to the limited self-repair capacities of cartilage. Cartilage tissue engineering based on stem cells and gene enhancement is a potential alternative for cartilage repair. Bone morphogenetic protein 2 (BMP2 has been shown to induce chondrogenic differentiation in mesenchymal stem cells (MSCs; however, maintaining the phenotypes of MSCs during cartilage repair since differentiation occurs along the endochondral ossification pathway. In this study, hypoxia inducible factor, or (HIF-1α, was determined to be a regulator of BMP2-induced chondrogenic differentiation, osteogenic differentiation, and endochondral bone formation. Methods: BMP2 was used to induce chondrogenic and osteogenic differentiation in stem cells and fetal limb development. After HIF-1α was added to the inducing system, any changes in the differentiation markers were assessed. Results: HIF-1α was found to potentiate BMP2-induced Sox9 and the expression of chondrogenesis by downstream markers, and inhibit Runx2 and the expression of osteogenesis by downstream markers in vitro. In subcutaneous stem cell implantation studies, HIF-1α was shown to potentiate BMP2-induced cartilage formation and inhibit endochondral ossification during ectopic bone/cartilage formation. In the fetal limb culture, HIF-1α and BMP2 synergistically promoted the expansion of the proliferating chondrocyte zone and inhibited chondrocyte hypertrophy and endochondral ossification. Conclusion: The results of this study indicated that, when combined with BMP2, HIF-1α induced MSC differentiation could become a new method of maintaining cartilage phenotypes during cartilage tissue engineering.

  12. 2-N, 6-O-sulfated chitosan-assisted BMP-2 immobilization of PCL scaffolds for enhanced osteoinduction

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Lingyan [Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); CSIRO Manufacturing, Bayview Avenue, Clayton, Victoria 3168 (Australia); Department of Prosthodontics, College of Stomatology, Ninth People' s Hospital, School of Medicine, Shanghai Jiao Tong University, 639 Zhizaoju Road, Shanghai 200011 (China); Yu, Yuanman [Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Wang, Jing, E-mail: biomatwj@163.com [Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Werkmeister, Jerome A [CSIRO Manufacturing, Bayview Avenue, Clayton, Victoria 3168 (Australia); McLean, Keith M, E-mail: Keith.McLean@csiro.au [CSIRO Manufacturing, Bayview Avenue, Clayton, Victoria 3168 (Australia); Liu, Changsheng, E-mail: liucs@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China)

    2017-05-01

    The aim of this study was to develop a 2-N, 6-O-sulfated chitosan (26SCS) modified electrospun fibrous PCL scaffold for bone morphogenetic protein-2 (BMP-2) delivery to improve osteoinduction. The PCL scaffold was modified by an aminolysis reaction using ethylenediamine (ED) and 26SCS was immobilized via electrostatic interactions (PCL-N-S). Scaffolds were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. In vitro BMP-2 adsorption and release kinetics indicated that modified PCL-N-S scaffolds showed higher levels of binding of BMP-2 (about 30–100 times), moderative burst release (about one third), and prolonged releasing time compared to the unmodified PCL scaffold. The bioactivity of released BMP-2 determined by alkaline phosphatase (ALP) activity assay was maintained and improved 8– 12 times with increasing concentration of immobilized 26SCS on the scaffolds. In vitro studies demonstrated that bone marrow mesenchymal stem cells (BMSCs) attached more readily to the PCL-N-S scaffolds with increased spreading. In conclusion, 26SCS modified PCL scaffolds can be a potent system for the sustained and bioactive delivery of BMP-2. - Graphical abstract: Limited self-regenerating capacity of human body makes the reconstruction of critical size bone defect a significant challenge. Although bone morphogenetic protein-2 (BMP-2) is an important differentiation factor inducing bone regeneration, it's short half-life in vivo and potent side effect at high dosage still show lots of concerns in the clinical use. Herein, modification of electrospun PCL scaffolds was presented through immobilizing of sulfated chitosan (26SCS). The modified scaffolds effectively improve the binding capacity of BMP-2 and exhibited an enhanced bioactivity and sustained release in vitro. Thus, the use of 26SCS modified PCL scaffolds combined with BMP-2 could be a useful scaffold for tissue

  13. Secreted phosphoprotein 24 kD (Spp24) inhibits growth of human pancreatic cancer cells caused by BMP-2

    International Nuclear Information System (INIS)

    Li, Chen-Shuang; Tian, Haijun; Zou, Min; Zhao, Ke-Wei; Li, Yawei; Lao, Lifeng; Brochmann, Elsa J.; Duarte, M. Eugenia L.; Daubs, Michael D.; Zhou, Yan-Heng; Murray, Samuel S.; Wang, Jeffrey C.

    2015-01-01

    The emerging role of bone morphogenetic proteins (BMPs) in the initiation and progression of multiple cancers has drawn great attention in cancer research. In this study, we report that BMP-2 can promote the proliferation of the pancreatic tumor cell line, PANC-1. Secreted phosphoprotein 24 kD (Spp24), a BMP binding protein, did not affect the proliferation of the cells but promoted the apoptosis of the cells in vitro. In a xeneograft tumor model using PANC-1 cells, BMP-2 dramatically promoted tumor growth, while Spp24 not only abolished the effect of BMP-2, but also dramatically induced tumor shrinking when used alone. Activation of Smad1/5/8 participated in this process as demonstrated by immunohistochemical staining of phosphorylated Smad 1/5/8. We conclude that Spp24 can be developed into a therapeutic agent that could be employed in clinical situations where the inhibition of BMPs and related proteins is advantageous. - Highlights: • Spp24 effectively inhibited the in vivo tumor growth of PANC-1. • BMP-2 dramatically promoted tumor growth by promoting PANC-1 proliferation. • Spp24 abolished the tumor growth effect of BMP-2 by promoting PANC-1 apoptosis. • Spp24 may be a candidate as a therapeutic agent of pancreatic cancer.

  14. Secreted phosphoprotein 24 kD (Spp24) inhibits growth of human pancreatic cancer cells caused by BMP-2

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chen-Shuang [Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing (China); Tian, Haijun, E-mail: haijuntianmd@gmail.com [Department of Orthopaedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai (China); Department of Orthopaedic Surgery, University of California, Los Angeles, Los Angeles, CA (United States); Department of Surgery, Bethune School of Medics, Shijiazhuang (China); Zou, Min [Department of Orthodontics, School and Hospital of Stomatology, Xi' an Jiaotong University, Xi' an (China); Zhao, Ke-Wei [Research Service, VA Greater Los Angeles Healthcare System, North Hills, CA (United States); Li, Yawei; Lao, Lifeng [Department of Orthopaedic Surgery, University of California, Los Angeles, Los Angeles, CA (United States); Brochmann, Elsa J. [Research Service, VA Greater Los Angeles Healthcare System, North Hills, CA (United States); Geriatric Research, Education and Clinical Center, VA Greater Los Angeles Healthcare System, North Hills, CA (United States); Department of Medicine, University of California, Los Angeles, Los Angeles, CA (United States); Duarte, M. Eugenia L. [National Institute of Traumatology and Orthopaedics, Rio de Janeiro (Brazil); Daubs, Michael D. [Division of Orthopaedic Surgery, Department of Surgery, University of Nevada School of Medicine, Las Vegas, NV (United States); Zhou, Yan-Heng, E-mail: yanhengzhou@vip.163.com [Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing (China); Murray, Samuel S. [Research Service, VA Greater Los Angeles Healthcare System, North Hills, CA (United States); Geriatric Research, Education and Clinical Center, VA Greater Los Angeles Healthcare System, North Hills, CA (United States); Department of Medicine, University of California, Los Angeles, Los Angeles, CA (United States); Wang, Jeffrey C. [Department of Orthopaedic Surgery, University of Southern California, Los Angeles, CA (United States)

    2015-10-16

    The emerging role of bone morphogenetic proteins (BMPs) in the initiation and progression of multiple cancers has drawn great attention in cancer research. In this study, we report that BMP-2 can promote the proliferation of the pancreatic tumor cell line, PANC-1. Secreted phosphoprotein 24 kD (Spp24), a BMP binding protein, did not affect the proliferation of the cells but promoted the apoptosis of the cells in vitro. In a xeneograft tumor model using PANC-1 cells, BMP-2 dramatically promoted tumor growth, while Spp24 not only abolished the effect of BMP-2, but also dramatically induced tumor shrinking when used alone. Activation of Smad1/5/8 participated in this process as demonstrated by immunohistochemical staining of phosphorylated Smad 1/5/8. We conclude that Spp24 can be developed into a therapeutic agent that could be employed in clinical situations where the inhibition of BMPs and related proteins is advantageous. - Highlights: • Spp24 effectively inhibited the in vivo tumor growth of PANC-1. • BMP-2 dramatically promoted tumor growth by promoting PANC-1 proliferation. • Spp24 abolished the tumor growth effect of BMP-2 by promoting PANC-1 apoptosis. • Spp24 may be a candidate as a therapeutic agent of pancreatic cancer.

  15. [miRNA profile of the human dental pulp cells during odontoblast differentiation induced by BMP-2].

    Science.gov (United States)

    Bao, Li-Rong; Zhao, Wen-Qing; Lin, Tian; Lu, Yan-Ling; Wu, Yu

    2017-10-01

    To screen and verify the differentially expressed microRNAs (miRNAs) during the differentiation of human dental pulp cells (hDPCs) to odontoblasts induced by BMP-2. The isolated hDPCs were cultured in vitro and induced by BMP-2. The levels of ALP, DMP-1 and DSPP were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). The potential characteristics of hDPCs were investigated by miRNA microarray and highly expressed miRNAs were selected with bio-information software for predicting target genes and their biological functions. Then the results were validated using qRT-PCR analysis for the selected miRNAs. Statistical analysis was performed using SPSS 18.0 software package. The expression of ALP, DSPP, and DMP-1 showed significantly higher levels in BMP-2 induced groups compared to the control group(Pfunction(33%), while the function of other 0.2% genes remained unknown. This study identified differential expression of miRNAs in BMP-2-induced odontoblastic differentiation of hDPCs, thus contributing to further investigations of regulatory mechanisms and biological effect of target genes in BMP-2-induced odontoblastic differentiation of hDPCs.

  16. Dual delivery of rhPDGF-BB and bone marrow mesenchymal stromal cells expressing the BMP2 gene enhance bone formation in a critical-sized defect model.

    Science.gov (United States)

    Park, Shin-Young; Kim, Kyoung-Hwa; Shin, Seung-Yun; Koo, Ki-Tae; Lee, Yong-Moo; Seol, Yang-Jo

    2013-11-01

    Bone tissue healing is a dynamic, orchestrated process that relies on multiple growth factors and cell types. Platelet-derived growth factor-BB (PDGF-BB) is released from platelets at wound sites and induces cellular migration and proliferation necessary for bone regeneration in the early healing process. Bone morphogenetic protein-2 (BMP-2), the most potent osteogenic differentiation inducer, directs new bone formation at the sites of bone defects. This study evaluated a combinatorial treatment protocol of PDGF-BB and BMP-2 on bone healing in a critical-sized defect model. To mimic the bone tissue healing process, a dual delivery approach was designed to deliver the rhPDGF-BB protein transiently during the early healing phase, whereas BMP-2 was supplied by rat bone marrow stromal cells (BMSCs) transfected with an adenoviral vector containing the BMP2 gene (AdBMP2) for prolonged release throughout the healing process. In in vitro experiments, the dual delivery of rhPDGF-BB and BMP2 significantly enhanced cell proliferation. However, the osteogenic differentiation of BMSCs was significantly suppressed even though the amount of BMP-2 secreted by the AdBMP2-transfected BMSCs was not significantly affected by the rhPDGF-BB treatment. In addition, dual delivery inhibited the mRNA expression of BMP receptor type II and Noggin in BMSCs. In in vivo experiments, critical-sized calvarial defects in rats showed enhanced bone regeneration by dual delivery of autologous AdBMP2-transfected BMSCs and rhPDGF-BB in both the amount of new bone formed and the bone mineral density. These enhancements in bone regeneration were greater than those observed in the group treated with AdBMP2-transfected BMSCs alone. In conclusion, the dual delivery of rhPDGF-BB and AdBMP2-transfected BMSCs improved the quality of the regenerated bone, possibly due to the modulation of PDGF-BB on BMP-2-induced osteogenesis.

  17. NF-kappaB specifically activates BMP-2 gene expression in growth plate chondrocytes in vivo and in a chondrocyte cell line in vitro.

    Science.gov (United States)

    Feng, Jian Q; Xing, Lianping; Zhang, Jiang-Hong; Zhao, Ming; Horn, Diane; Chan, Jeannie; Boyce, Brendan F; Harris, Stephen E; Mundy, Gregory R; Chen, Di

    2003-08-01

    Bone morphogenetic protein-2 (BMP-2) regulates growth plate chondrogenesis during development and postnatal bone growth, but the control mechanisms of BMP-2 expression in growth plate chondrocytes are unknown. Here we have used both in vitro and in vivo approaches to demonstrate that transcription factor, NF-kappaB, regulates BMP-2 gene expression in chondrocytes. Two putative NF-kappaB response elements were found in the -2712/+165 region of the BMP-2 gene. Cotransfection of mutant I-kappaBalpha expression plasmids with BMP-2 promoter-luciferase reporters into TMC-23 chondrocyte cell line suppressed BMP-2 transcription. Mutations in NF-kappaB response elements in the BMP-2 gene lead to decreases in BMP-2 promoter activity. Electrophoretic mobility shift assay using nuclear extracts from TMC-23 chondrocytic cells revealed that the NF-kappaB subunits p50 and p65 bound to the NF-kappaB response elements of the BMP-2 gene. Thus, NF-kappaB may positively regulate BMP-2 gene transcription. Consistent with these findings, expression of BMP-2 mRNA was significantly reduced in growth plate chondrocytes in NF-kappaB p50/p52 dKO mice, which associated with decreased numbers of 5-bromo-2'-deoxyuridine (BrdUrd)-positive cells in the proliferating zone of growth plate in these mice. Therefore, in postnatal growth plate chondrocytes, expression of BMP-2 is regulated by NF-kappaB, which may play an important role in chondrogenesis.

  18. Duplications involving a conserved regulatory element downstream of BMP2 are associated with brachydactyly type A2

    DEFF Research Database (Denmark)

    Dathe, Katarina; Kjaer, Klaus W; Brehm, Anja

    2009-01-01

    Autosomal-dominant brachydactyly type A2 (BDA2), a limb malformation characterized by hypoplastic middle phalanges of the second and fifth fingers, has been shown to be due to mutations in the Bone morphogenetic protein receptor 1B (BMPR1B) or in its ligand Growth and differentiation factor 5 (GDF5......). A linkage analysis performed in a mutation-negative family identified a novel locus for BDA2 on chromosome 20p12.3 that incorporates the gene for Bone morphogenetic protein 2 (BMP2). No point mutation was identified in BMP2, so a high-density array CGH analysis covering the critical interval...... within the identified duplication. Our results reveal an additional functional mechanism for the pathogenesis of BDA2, which is duplication of a regulatory element that affects the expression of BMP2 in the developing limb....

  19. Strontium doping promotes bioactivity of rhBMP-2 upon calcium phosphate cement via elevated recognition and expression of BMPR-IA.

    Science.gov (United States)

    Huang, Baolin; Tian, Yu; Zhang, Wenjing; Ma, Yifan; Yuan, Yuan; Liu, Changsheng

    2017-11-01

    Preserving and improving osteogenic activity of bone morphogenetic protein-2 (BMP-2) upon implants remains one of the key limitations in bone regeneration. With calcium phosphate cement (CPC) as model, we have developed a series of strontium (Sr)-doped CPC (SCPC) to address this issue. The effects of fixed Sr on the bioactivity of recombinant human BMP-2 (rhBMP-2) as well as the underlying mechanism were investigated. The results suggested that the rhBMP-2-induced osteogenic activity was significantly promoted upon SCPCs, especially with a low amount of fixed Sr (SrCO 3 content IA (BMPR-IA) to rhBMP-2 and an increased expression of BMPR-IA in C2C12 model cells. As a result, the activations of BMP-induced signaling pathways were different in C2C12 cells incubated upon CPC/rhBMP-2 and SCPCs/rhBMP-2. These findings explicitly decipher the mechanism of SCPCs promoting osteogenic bioactivity of rhBMP-2 and signify the promising application of the SCPCs/rhBMP-2 matrix in bone regeneration implants. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Adenoviral Mediated Expression of BMP2 by Bone Marrow Stromal Cells Cultured in 3D Copolymer Scaffolds Enhances Bone Formation.

    Science.gov (United States)

    Sharma, Sunita; Sapkota, Dipak; Xue, Ying; Sun, Yang; Finne-Wistrand, Anna; Bruland, Ove; Mustafa, Kamal

    2016-01-01

    Selection of appropriate osteoinductive growth factors, suitable delivery method and proper supportive scaffold are critical for a successful outcome in bone tissue engineering using bone marrow stromal cells (BMSC). This study examined the molecular and functional effect of a combination of adenoviral mediated expression of bone morphogenetic protein-2 (BMP2) in BMSC and recently developed and characterized, biodegradable Poly(L-lactide-co-є-caprolactone){poly(LLA-co-CL)}scaffolds in osteogenic molecular changes and ectopic bone formation by using in vitro and in vivo approaches. Pathway-focused custom PCR array, validation using TaqMan based quantitative RT-PCR (qRT-PCR) and ALP staining showed significant up-regulation of several osteogenic and angiogenic molecules, including ALPL and RUNX2 in ad-BMP2 BMSC group grown in poly(LLA-co-CL) scaffolds both at 3 and 14 days. Micro CT and histological analyses of the subcutaneously implanted scaffolds in NOD/SCID mice revealed significantly increased radiopaque areas, percentage bone volume and formation of vital bone in ad-BMP2 scaffolds as compared to the control groups both at 2 and 8 weeks. The increased bone formation in the ad-BMP2 group in vivo was paralleled at the molecular level with concomitant over-expression of a number of osteogenic and angiogenic genes including ALPL, RUNX2, SPP1, ANGPT1. The increased bone formation in ad-BMP2 explants was not found to be associated with enhanced endochondral activity as evidenced by qRT-PCR (SOX9 and FGF2) and Safranin O staining. Taken together, combination of adenoviral mediated BMP-2 expression in BMSC grown in the newly developed poly(LLA-co-CL) scaffolds induced expression of osteogenic markers and enhanced bone formation in vivo.

  1. Differential effects of BMP-2 and TGF-beta1 on chondrogenic differentiation of adipose derived stem cells

    DEFF Research Database (Denmark)

    Mehlhorn, A T; Niemeyer, P; Kaschte, K

    2007-01-01

    transcriptional regulation of Dlx-5, Msx-2 and Runx-2. MATERIALS AND METHODS: Encapsulated ASC were cultured for 14 days in medium containing TGF-beta1 and/or BMP-2. mRNA expression of the extracellular matrix molecules col2a1, cartilage oligomeric matrix protein, col10a1, alkaline phosphatase (AP......) and transcription factors Msx-2, Dlx-5 and Runx-2 was analysed. Release of glycosaminoglycans, collagen types II and X into the extracellular matrix was demonstrated. RESULTS: BMP-2 and TGF-beta1 induced a chondrogenic phenotype in ASC. Combined growth factor treatment had a synergistic effect on col10a1...

  2. Select polyphenolic fractions from dried plum enhance osteoblast activity through BMP-2 signaling.

    Science.gov (United States)

    Graef, Jennifer L; Rendina-Ruedy, Elizabeth; Crockett, Erica K; Ouyang, Ping; King, Jarrod B; Cichewicz, Robert H; Lucas, Edralin A; Smith, Brenda J

    2018-05-01

    Dried plum supplementation has been shown to enhance bone formation while suppressing bone resorption. Evidence from previous studies has demonstrated that these responses can be attributed in part to the fruit's polyphenolic compounds. The purpose of this study was to identify the most bioactive polyphenolic fractions of dried plum with a focus on their osteogenic activity and to investigate their mechanisms of action under normal and inflammatory conditions. Utilizing chromatographic techniques, six fractions of polyphenolic compounds were prepared from a crude extract of dried plum. Initial screening assays revealed that two fractions (DP-FrA and DP-FrB) had the greatest osteogenic potential. Subsequent experiments using primary bone-marrow-derived osteoblast cultures demonstrated these two fractions enhanced extracellular alkaline phosphatase (ALP), an indicator of osteoblast activity, and mineralized nodule formation under normal conditions. Both fractions enhanced bone morphogenetic protein (BMP) signaling, as indicated by increased Bmp2 and Runx2 gene expression and protein levels of phosphorylated Smad1/5. DP-FrB was most effective at up-regulating Tak1 and Smad1, as well as protein levels of phospho-p38. Under inflammatory conditions, TNF-α suppressed ALP and tended to decrease nodule formation (P=.0674). This response coincided with suppressed gene expression of Bmp2 and the up-regulation of Smad6, an inhibitor of BMP signaling. DP-FrA and DP-FrB partially normalized these responses. Our results show that certain fractions of polyphenolic compounds in dried plum up-regulate osteoblast activity by enhancing BMP signaling, and when this pathway is inhibited by TNF-α, the osteogenic response is attenuated. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Stiffness-dependent cellular internalization of matrix-bound BMP-2 and its relation to Smad and non-Smad signaling.

    Science.gov (United States)

    Gilde, Flora; Fourel, Laure; Guillot, Raphael; Pignot-Paintrand, Isabelle; Okada, Takaharu; Fitzpatrick, Vincent; Boudou, Thomas; Albiges-Rizo, Corinne; Picart, Catherine

    2016-12-01

    Surface coatings delivering BMP are a promising approach to render biomaterials osteoinductive. In contrast to soluble BMPs which can interact with their receptors at the dorsal side of the cell, BMPs presented as an insoluble cue physically bound to a biomimetic matrix, called here matrix-bound (bBMP-2), are presented to cells by their ventral side. To date, BMP-2 internalization and signaling studies in cell biology have always been performed by adding soluble (sBMP-2) to cells adhered on cell culture plates or glass slides, which will be considered here as a "reference" condition. However, whether and how matrix-bound BMP-2 can be internalized by cells and its relation to canonical (SMAD) and non-canonical signaling (ALP) remain open questions. In this study, we investigated the uptake and processing of BMP-2 by C2C12 myoblasts. This BMP-2 was presented either embedded in polyelectrolyte multilayer films (matrix-bound presentation) or as soluble form. Using fluorescently labeled BMP-2, we showed that the amount of matrix-bound BMP-2 internalized is dependent on the level of crosslinking of the polyelectrolyte films. Cav-1-mediated internalization is related to both SMAD and ALP signaling, while clathrin-mediated is only related to ALP signaling. BMP-2 internalization was independent of the presentation mode (sBMP-2 versus bBMP-2) for low crosslinked films (soft, EDC10) in striking contrast with high crosslinked (stiff, EDC70) films where internalization was much lower and slower for bBMP-2. As anticipated, internalization of sBMP-2 barely depended on the underlying matrix. Taken together, these results indicate that BMP-2 internalization can be tuned by the underlying matrix and activates downstream BMP-2 signaling, which is key for the effective formation of bone tissue. The presentation of growth factors from material surfaces currently presents significant challenges in academic research, clinics and industry. Being able to deliver efficiently these growth

  4. The 5th Symposium on Post-Transcriptional Regulation of Plant Gene Expression (PTRoPGE)

    Energy Technology Data Exchange (ETDEWEB)

    Karen S. Browning; Marie Petrocek; Bonnie Bartel

    2006-06-01

    The 5th Symposium on Post-Transcriptional Regulation of Plant Gene Expression (PTRoPGE) will be held June 8-12, 2005 at the University of Texas at Austin. Exciting new and ongoing discoveries show significant regulation of gene expression occurs after transcription. These post-transcriptional control events in plants range from subtle regulation of transcribed genes and phosphorylation, to the processes of gene regulation through small RNAs. This meeting will focus on the regulatory role of RNA, from transcription, through translation and finally degradation. The cross-disciplinary design of this meeting is necessary to encourage interactions between researchers that have a common interest in post-transcriptional gene expression in plants. By bringing together a diverse group of plant molecular biologist and biochemists at all careers stages from across the world, this meeting will bring about more rapid progress in understanding how plant genomes work and how genes are finely regulated by post-transcriptional processes to ultimately regulate cells.

  5. 3D bioprinting of BMSC-laden methacrylamide gelatin scaffolds with CBD-BMP2-collagen microfibers.

    Science.gov (United States)

    Du, Mingchun; Chen, Bing; Meng, Qingyuan; Liu, Sumei; Zheng, Xiongfei; Zhang, Cheng; Wang, Heran; Li, Hongyi; Wang, Nuo; Dai, Jianwu

    2015-12-18

    Three-dimensional (3D) bioprinting combines biomaterials, cells and functional components into complex living tissues. Herein, we assembled function-control modules into cell-laden scaffolds using 3D bioprinting. A customized 3D printer was able to tune the microstructure of printed bone mesenchymal stem cell (BMSC)-laden methacrylamide gelatin scaffolds at the micrometer scale. For example, the pore size was adjusted to 282 ± 32 μm and 363 ± 60 μm. To match the requirements of the printing nozzle, collagen microfibers with a length of 22 ± 13 μm were prepared with a high-speed crusher. Collagen microfibers bound bone morphogenetic protein 2 (BMP2) with a collagen binding domain (CBD) as differentiation-control module, from which BMP2 was able to be controllably released. The differentiation behaviors of BMSCs in the printed scaffolds were compared in three microenvironments: samples without CBD-BMP2-collagen microfibers in the growth medium, samples without microfibers in the osteogenic medium and samples with microfibers in the growth medium. The results indicated that BMSCs showed high cell viability (>90%) during printing; CBD-BMP2-collagen microfibers induced BMSC differentiation into osteocytes within 14 days more efficiently than the osteogenic medium. Our studies suggest that these function-control modules are attractive biomaterials and have potential applications in 3D bioprinting.

  6. Bone regeneration by gelatin hydro-gel seat containing BMP-2 and its application to canine orbital floor fracture Model

    International Nuclear Information System (INIS)

    Mochizuki, Yuichi

    2007-01-01

    Reported are preparation of the gel seat in the title (GHG) for sustained release of BMP-2 (bone morphogenetic protein-2) and its application to the fracture model of orbital floor of the dog. The chemically linked GHG was prepared from gelatin and glutaraldehyde and lyophilized. BMP-2 solution was dropped on the GHG seat to be contained there. To see the biobehavior of BMP-2 and GHG, they were labeled with 125 I and were given subcutaneously in the back of nude mice, of which remaining radioactivity was periodically measured by Aloka ARC-310B gamma counter. This experiment revealed the sustained release of BMP-2 along with degradation of the GHG. Then a complex of the GHG and bio-degradable polymer (L-lactide-ε-caprolactone) was prepared and implanted to the artificially fractured region (10 x 10 mm) of dog orbit floor, of which recovering process was evaluated by analysis of bone structure with soft X-ray (SOFRON, TRS-1005) roentgenography, histology, and micro-CT imaging (Comscantecno's Scan Xmate-A090S) for trabecular bone volume, thickness, number and separation. This experiment revealed that new bone was effectively induced to regenerate on the complex, of which structure was found similar to the normal trabecula. Thus in future, the complex can be useful for ideal treatment of the orbit floor fracture without necessity of donor. (R.T.)

  7. In vitro and in vivo evaluation of bone morphogenetic protein-2 (BMP-2) immobilized collagen-coated polyetheretherketone (PEEK)

    Science.gov (United States)

    Du, Ya-Wei; Zhang, Li-Nan; Ye, Xin; Nie, He-Min; Hou, Zeng-Tao; Zeng, Teng-Hui; Yan, Guo-Ping; Shang, Peng

    2015-03-01

    Polyetheretherketone (PEEK) is regarded as one of the most potential candidates of biomaterials in spinal implant applications. However, as a bioinert material, PEEK plays a limited role in osteoconduction and osseointegration. In this study, recombinant human bone morphogenetic protein-2 (rhBMP-2) was immobilized onto the surface of collagen-coated PEEK in order to prepare a multi-functional material. After adsorbed onto the PEEK surface by hydrophobic interaction, collagen was cross-linked with N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). EDC/NHS system also contributed to the immobilization of rhBMP-2. Water contact angle tests, XPS and SEM clearly demonstrated the surface changes. ELISA tests quantified the amount of rhBMP-2 immobilized and the release over a period of 30 d. In vitro evaluation proved that the osteogenesis differentiation rate was higher when cells were cultured on modified PEEK discs than on regular ones. In vivo tests were conducted and positive changes of major parameters were presented. This report demonstrates that the rhBMP-2 immobilized method for PEEK modification increase bioactivity in vitro and in vivo, suggesting its practicability in orthopedic and spinal clinical applications.

  8. Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Zhiwei; Huangfu, Changxin; Wang, Yanying; Ge, Hongwei; Yao, Yao; Zou, Ping; Wang, Guangtu [College of Science, Sichuan Agricultural University, Ya' an 625014 (China); He, Hua [Institute of Animal Genetics and Breeding, Sichuan Agricultural University, Wenjiang, Sichuan 611130 (China); Rao, Hanbing, E-mail: rhbscu@gmail.com [College of Science, Sichuan Agricultural University, Ya' an 625014 (China)

    2015-07-01

    The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g{sup −1}, respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG < 0) and entropy increasing (ΔS > 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR. - Highlights: • A novel protein adsorption studies based on sheet, rod and whisker of HA were designed. • Kinetic and thermodynamics parameters of BMP-2 and HA bonded materials were evaluated. • Surface topographies of the HA effect BMP-2 adsorption • The HA-whisker material had excellent adsorption performance for protein enrichment. • The electrostatic interaction is responsible for the

  9. Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features

    International Nuclear Information System (INIS)

    Lu, Zhiwei; Huangfu, Changxin; Wang, Yanying; Ge, Hongwei; Yao, Yao; Zou, Ping; Wang, Guangtu; He, Hua; Rao, Hanbing

    2015-01-01

    The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g −1 , respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG < 0) and entropy increasing (ΔS > 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR. - Highlights: • A novel protein adsorption studies based on sheet, rod and whisker of HA were designed. • Kinetic and thermodynamics parameters of BMP-2 and HA bonded materials were evaluated. • Surface topographies of the HA effect BMP-2 adsorption • The HA-whisker material had excellent adsorption performance for protein enrichment. • The electrostatic interaction is responsible for the BMP-2

  10. Low-dose rhBMP2/7 heterodimer to reconstruct peri-implant bone defects: a micro-CT evaluation

    NARCIS (Netherlands)

    Wang, J.; Zheng, Y.; Zhao, J.; Liu, T.; Gao, L.; Gu, Z.; Wu, G.

    2012-01-01

    Objectives To delineate the dynamic micro-architectures of bone induced by low-dose bone morphogenetic protein (BMP)-2/7 heterodimer in peri-implant bone defects compared to BMP2 and BMP7 homodimer. Material and Methods Peri-implant bone defects (8 mm in diameter, 4 mm in depth) were created

  11. Time kinetics of bone defect healing in response to BMP-2 and GDF-5 characterised by in vivo biomechanics

    Directory of Open Access Journals (Sweden)

    D Wulsten

    2011-02-01

    Full Text Available This study reports that treatment of osseous defects with different growth factors initiates distinct rates of repair. We developed a new method for monitoring the progression of repair, based upon measuring the in vivo mechanical properties of healing bone. Two different members of the bone morphogenetic protein (BMP family were chosen to initiate defect healing: BMP-2 to induce osteogenesis, and growth-and-differentiation factor (GDF-5 to induce chondrogenesis. To evaluate bone healing, BMPs were implanted into stabilised 5 mm bone defects in rat femurs and compared to controls. During the first two weeks, in vivo biomechanical measurements showed similar values regardless of the treatment used. However, 2 weeks after surgery, the rhBMP-2 group had a substantial increase in stiffness, which was supported by the imaging modalities. Although the rhGDF-5 group showed comparable mechanical properties at 6 weeks as the rhBMP-2 group, the temporal development of regenerating tissues appeared different with rhGDF-5, resulting in a smaller callus and delayed tissue mineralisation. Moreover, histology showed the presence of cartilage in the rhGDF-5 group whereas the rhBMP-2 group had no cartilaginous tissue.Therefore, this study shows that rhBMP-2 and rhGDF-5 treated defects, under the same conditions, use distinct rates of bone healing as shown by the tissue mechanical properties. Furthermore, results showed that in vivo biomechanical method is capable of detecting differences in healing rate by means of change in callus stiffness due to tissue mineralisation.

  12. Myocardial Tbx20 regulates early atrioventricular canal formation and endocardial epithelial-mesenchymal transition via Bmp2.

    Science.gov (United States)

    Cai, Xiaoqiang; Nomura-Kitabayashi, Aya; Cai, Weibin; Yan, Jianyun; Christoffels, Vincent M; Cai, Chen-Leng

    2011-12-15

    During early embryogenesis, the formation of the cardiac atrioventricular canal (AVC) facilitates the transition of the heart from a linear tube into a chambered organ. However, the genetic pathways underlying this developmental process are poorly understood. The T-box transcription factor Tbx20 is expressed predominantly in the AVC of early heart tube. It was shown that Tbx20 activates Nmyc1 and suppresses Tbx2 expression to promote proliferation and specification of the atrial and ventricular chambers, yet it is not known if Tbx20 is involved in early AVC development. Here, we report that mice lacking Tbx20 in the AVC myocardium fail to form the AVC constriction, and the endocardial epithelial-mesenchymal transition (EMT) is severely perturbed. Tbx20 maintains expression of a variety of genes, including Bmp2, Tbx3 and Hand1 in the AVC myocardium. Intriguingly, we found Bmp2 downstream genes involved in the EMT initiation are also downregulated. In addition, re-expression of Bmp2 in the AVC myocardium substantially rescues the EMT defects resulting from the lack of Tbx20, suggesting Bmp2 is one of the key downstream targets of Tbx20 in AVC development. Our data support a complex signaling network with Tbx20 suppressing Tbx2 in the AVC myocardium but also indirectly promoting Tbx2 expression through Bmp2. The spatiotemporal expression of Tbx2 in the AVC appears to be balanced between these two opposing signals. Overall, our study provides genetic evidence that Tbx20 has essential roles in regulating AVC development that coordinate early cardiac chamber formation. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. In silico Mechano-Chemical Model of Bone Healing for the Regeneration of Critical Defects: The Effect of BMP-2.

    Directory of Open Access Journals (Sweden)

    Frederico O Ribeiro

    Full Text Available The healing of bone defects is a challenge for both tissue engineering and modern orthopaedics. This problem has been addressed through the study of scaffold constructs combined with mechanoregulatory theories, disregarding the influence of chemical factors and their respective delivery devices. Of the chemical factors involved in the bone healing process, bone morphogenetic protein-2 (BMP-2 has been identified as one of the most powerful osteoinductive proteins. The aim of this work is to develop and validate a mechano-chemical regulatory model to study the effect of BMP-2 on the healing of large bone defects in silico. We first collected a range of quantitative experimental data from the literature concerning the effects of BMP-2 on cellular activity, specifically proliferation, migration, differentiation, maturation and extracellular matrix production. These data were then used to define a model governed by mechano-chemical stimuli to simulate the healing of large bone defects under the following conditions: natural healing, an empty hydrogel implanted in the defect and a hydrogel soaked with BMP-2 implanted in the defect. For the latter condition, successful defect healing was predicted, in agreement with previous in vivo experiments. Further in vivo comparisons showed the potential of the model, which accurately predicted bone tissue formation during healing, bone tissue distribution across the defect and the quantity of bone inside the defect. The proposed mechano-chemical model also estimated the effect of BMP-2 on cells and the evolution of healing in large bone defects. This novel in silico tool provides valuable insight for bone tissue regeneration strategies.

  14. Repair of Cranial Bone Defects Using rhBMP2 and Submicron Particle of Biphasic Calcium Phosphate Ceramics with Through-Hole

    Directory of Open Access Journals (Sweden)

    Byung-Chul Jeong

    2015-01-01

    Full Text Available Recently a submicron particle of biphasic calcium phosphate ceramic (BCP with through-hole (donut-shaped BCP (d-BCP was developed for improving the osteoconductivity. This study was performed to examine the usefulness of d-BCP for the delivery of osteoinductive rhBMP2 and the effectiveness on cranial bone regeneration. The d-BCP was soaked in rhBMP2 solution and then freeze-dried. Scanning electron microscope (SEM, energy dispersive spectroscopy (EDS, and Raman spectroscopy analyses confirmed that rhBMP2 was well delivered onto the d-BCP surface and the through-hole. The bioactivity of the rhBMP2/d-BCP composite was validated in MC3T3-E1 cells as an in vitro model and in critical-sized cranial defects in C57BL/6 mice. When freeze-dried d-BCPs with rhBMP2 were placed in transwell inserts and suspended above MC3T3-E1, alkaline phosphatase activity and osteoblast-specific gene expression were increased compared to non-rhBMP2-containing d-BCPs. For evaluating in vivo effectiveness, freeze-dried d-BCPs with or without rhBMP2 were implanted into critical-sized cranial defects. Microcomputed tomography and histologic analysis showed that rhBMP2-containing d-BCPs significantly enhanced cranial bone regeneration compared to non-rhBMP2-containing control. These results suggest that a combination of d-BCP and rhBMP2 can accelerate bone regeneration, and this could be used to develop therapeutic strategies in hard tissue healing.

  15. Repair of Cranial Bone Defects Using rhBMP2 and Submicron Particle of Biphasic Calcium Phosphate Ceramics with Through-Hole.

    Science.gov (United States)

    Jeong, Byung-Chul; Choi, Hyuck; Hur, Sung-Woong; Kim, Jung-Woo; Oh, Sin-Hye; Kim, Hyun-Seung; Song, Soo-Chang; Lee, Keun-Bae; Park, Kwang-Bum; Koh, Jeong-Tae

    2015-01-01

    Recently a submicron particle of biphasic calcium phosphate ceramic (BCP) with through-hole (donut-shaped BCP (d-BCP)) was developed for improving the osteoconductivity. This study was performed to examine the usefulness of d-BCP for the delivery of osteoinductive rhBMP2 and the effectiveness on cranial bone regeneration. The d-BCP was soaked in rhBMP2 solution and then freeze-dried. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and Raman spectroscopy analyses confirmed that rhBMP2 was well delivered onto the d-BCP surface and the through-hole. The bioactivity of the rhBMP2/d-BCP composite was validated in MC3T3-E1 cells as an in vitro model and in critical-sized cranial defects in C57BL/6 mice. When freeze-dried d-BCPs with rhBMP2 were placed in transwell inserts and suspended above MC3T3-E1, alkaline phosphatase activity and osteoblast-specific gene expression were increased compared to non-rhBMP2-containing d-BCPs. For evaluating in vivo effectiveness, freeze-dried d-BCPs with or without rhBMP2 were implanted into critical-sized cranial defects. Microcomputed tomography and histologic analysis showed that rhBMP2-containing d-BCPs significantly enhanced cranial bone regeneration compared to non-rhBMP2-containing control. These results suggest that a combination of d-BCP and rhBMP2 can accelerate bone regeneration, and this could be used to develop therapeutic strategies in hard tissue healing.

  16. Lack of Obvious Influence of PLLA Nanofibers on the Gene Expression of BMP-2 and VEGF during Growth and Differentiation of Human Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Markus D. Schofer

    2009-01-01

    Full Text Available Growth factors like bone morphogenetic protein 2 (BMP-2 and vascular endothelial growth factor (VEGF play an important role in bone remodeling and fracture repair. Therefore, with respect to tissue engineering, an artificial graft should have no negative impact on the expression of these factors. In this context, the aim of this study was to analyze the impact of poly(L-lactic acid (PLLA nanofibers on VEGF and BMP-2 gene expression during the time course of human mesenchymal stem cell (hMSC differentiation towards osteoblasts. PLLA matrices were seeded with hMSCs and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of VEGF and BMP-2. Furthermore, BMP-2–enwoven PLLA nanofibers were used in order to elucidate whether initial down-regulation of growth factor expression could be compensated. Although there was a great interpatient variability with respect to the expression of VEGF and BMP-2, PLLA nanofibers tend to result in a down-regulation in BMP-2 expression during the early phase of cultivation. This effect was diminished in the case of VEGF gene expression. The initial down-regulation was overcome when BMP-2 was directly incorporated into the PLLA nanofibers by electrospinning. Furthermore, the incorporation of BMP-2 into the PLLA nanofibers resulted in an increase in VEGF gene expression. Summarized, the results indicate that the PLLA nanofibers have little effect on growth factor production. An enhancement in gene expression of BMP-2 and VEGF can be achieved by an incorporation of BMP-2 into the PLLA nanofibers.

  17. Lack of Obvious Influence of PLLA Nanofibers on the Gene Expression of BMP-2 and VEGF during Growth and Differentiation of Human Mesenchymal Stem Cells

    Science.gov (United States)

    Schofer, Markus D.; Fuchs-Winkelmann, S.; Wack, C.; Rudisile, M.; Dersch, R.; Leifeld, I.; Wendorff, J.; Greiner, A.; Paletta, J. R. J.; Boudriot, U.

    2009-01-01

    Growth factors like bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF) play an important role in bone remodeling and fracture repair. Therefore, with respect to tissue engineering, an artificial graft should have no negative impact on the expression of these factors. In this context, the aim of this study was to analyze the impact of poly(L-lactic acid) (PLLA) nanofibers on VEGF and BMP-2 gene expression during the time course of human mesenchymal stem cell (hMSC) differentiation towards osteoblasts. PLLA matrices were seeded with hMSCs and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of VEGF and BMP-2. Furthermore, BMP-2–enwoven PLLA nanofibers were used in order to elucidate whether initial down-regulation of growth factor expression could be compensated. Although there was a great interpatient variability with respect to the expression of VEGF and BMP-2, PLLA nanofibers tend to result in a down-regulation in BMP-2 expression during the early phase of cultivation. This effect was diminished in the case of VEGF gene expression. The initial down-regulation was overcome when BMP-2 was directly incorporated into the PLLA nanofibers by electrospinning. Furthermore, the incorporation of BMP-2 into the PLLA nanofibers resulted in an increase in VEGF gene expression. Summarized, the results indicate that the PLLA nanofibers have little effect on growth factor production. An enhancement in gene expression of BMP-2 and VEGF can be achieved by an incorporation of BMP-2 into the PLLA nanofibers. PMID:19412560

  18. High SINE RNA Expression Correlates with Post-Transcriptional Downregulation of BRCA1

    Directory of Open Access Journals (Sweden)

    Giovanni Bosco

    2013-04-01

    Full Text Available Short Interspersed Nuclear Elements (SINEs are non-autonomous retrotransposons that comprise a large fraction of the human genome. SINEs are demethylated in human disease, but whether SINEs become transcriptionally induced and how the resulting transcripts may affect the expression of protein coding genes is unknown. Here, we show that downregulation of the mRNA of the tumor suppressor gene BRCA1 is associated with increased transcription of SINEs and production of sense and antisense SINE small RNAs. We find that BRCA1 mRNA is post-transcriptionally down-regulated in a Dicer and Drosha dependent manner and that expression of a SINE inverted repeat with sequence identity to a BRCA1 intron is sufficient for downregulation of BRCA1 mRNA. These observations suggest that transcriptional activation of SINEs could contribute to a novel mechanism of RNA mediated post-transcriptional silencing of human genes.

  19. Insights into the post-transcriptional regulation of the mitochondrial electron transport chain.

    Science.gov (United States)

    Sirey, Tamara M; Ponting, Chris P

    2016-10-15

    The regulation of the mitochondrial electron transport chain is central to the control of cellular homeostasis. There are significant gaps in our understanding of how the expression of the mitochondrial and nuclear genome-encoded components of the electron transport chain are co-ordinated, and how the assembly of the protein complexes that constitute the electron transport chain are regulated. Furthermore, the role post-transcriptional gene regulation may play in modulating these processes needs to be clarified. This review summarizes the current knowledge regarding the post-transcriptional gene regulation of the electron transport chain and highlights how noncoding RNAs may contribute significantly both to complex electron transport chain regulatory networks and to mitochondrial dysfunction. © 2016 The Author(s).

  20. Modeling post-transcriptional regulation activity of small non-coding RNAs in Escherichia coli.

    Science.gov (United States)

    Wang, Rui-Sheng; Jin, Guangxu; Zhang, Xiang-Sun; Chen, Luonan

    2009-04-29

    Transcriptional regulation is a fundamental process in biological systems, where transcription factors (TFs) have been revealed to play crucial roles. In recent years, in addition to TFs, an increasing number of non-coding RNAs (ncRNAs) have been shown to mediate post-transcriptional processes and regulate many critical pathways in both prokaryotes and eukaryotes. On the other hand, with more and more high-throughput biological data becoming available, it is possible and imperative to quantitatively study gene regulation in a systematic and detailed manner. Most existing studies for inferring transcriptional regulatory interactions and the activity of TFs ignore the possible post-transcriptional effects of ncRNAs. In this work, we propose a novel framework to infer the activity of regulators including both TFs and ncRNAs by exploring the expression profiles of target genes and (post)transcriptional regulatory relationships. We model the integrated regulatory system by a set of biochemical reactions which lead to a log-bilinear problem. The inference process is achieved by an iterative algorithm, in which two linear programming models are efficiently solved. In contrast to available related studies, the effects of ncRNAs on transcription process are considered in this work, and thus more reasonable and accurate reconstruction can be expected. In addition, the approach is suitable for large-scale problems from the viewpoint of computation. Experiments on two synthesized data sets and a model system of Escherichia coli (E. coli) carbon source transition from glucose to acetate illustrate the effectiveness of our model and algorithm. Our results show that incorporating the post-transcriptional regulation of ncRNAs into system model can mine the hidden effects from the regulation activity of TFs in transcription processes and thus can uncover the biological mechanisms in gene regulation in a more accurate manner. The software for the algorithm in this paper is available

  1. Regulation of Adult CNS Axonal Regeneration by the Post-transcriptional Regulator Cpeb1

    Directory of Open Access Journals (Sweden)

    Wilson Pak-Kin Lou

    2018-01-01

    Full Text Available Adult mammalian central nervous system (CNS neurons are unable to regenerate following axonal injury, leading to permanent functional impairments. Yet, the reasons underlying this regeneration failure are not fully understood. Here, we studied the transcriptome and translatome shortly after spinal cord injury. Profiling of the total and ribosome-bound RNA in injured and naïve spinal cords identified a substantial post-transcriptional regulation of gene expression. In particular, transcripts associated with nervous system development were down-regulated in the total RNA fraction while remaining stably loaded onto ribosomes. Interestingly, motif association analysis of post-transcriptionally regulated transcripts identified the cytoplasmic polyadenylation element (CPE as enriched in a subset of these transcripts that was more resistant to injury-induced reduction at the transcriptome level. Modulation of these transcripts by overexpression of the CPE binding protein, Cpeb1, in mouse and Drosophila CNS neurons promoted axonal regeneration following injury. Our study uncovered a global evolutionarily conserved post-transcriptional mechanism enhancing regeneration of injured CNS axons.

  2. Expression of human bone morphogenetic protein (BMP-2 and BMP-4 genes in transgenic bovine fibroblasts Expressão dos genes bone morphogenetic protein (BMP-2 e BMP-4 em fibroblastos bovinos transgênicos

    Directory of Open Access Journals (Sweden)

    C. Oleskovicz

    2004-08-01

    Full Text Available cDNAs dos genes bone morphogenetic protein-2 (BMP-2 e bone morphogenetic protein-4 (BMP-4 foram sintetizados a partir de RNA total extraído de tecidos ósseos de pacientes que apresentavam trauma facial (fraturas do maxilar entre o 7º e o 10º dia pós-trauma e clonados num vetor para expressão em células mamíferas, sob controle do promotor de citomegalovírus (CMV. Os vetores contendo os genes BMP-2 e o BMP-4 foram utilizados para a transfecção de fibroblastos bovinos. mRNAs foram indiretamente detectados por RT-PCR nas células transfectadas. As proteínas BMP-2 e BMP-4 foram detectadas mediante análises de Western blot. Os resultados demonstram a possibilidade de produção desses fatores de crescimento celular em fibroblastos bovinos. Essas células poderão ser utilizadas como fontes doadoras de material genético para a técnica de transferência nuclear na geração de animais transgênicos.

  3. Assessment of a polyelectrolyte multilayer film coating loaded with BMP-2 on titanium and PEEK implants in the rabbit femoral condyle

    Science.gov (United States)

    Guillot, R.; Pignot-Paintrand, I.; Lavaud, J.; Decambron, A.; Bourgeois, E.; Josserand, V.; Logeart-Avramoglou, D.; Viguier, E.; Picart, C.

    2016-01-01

    The aim of this study was to evaluate the osseointegration of titanium implants (Ti-6Al-4V, noted here TA6V) and poly(etheretherketone) PEEK implants induced by a BMP-2-delivering surface coating made of polyelectrolyte multilayer films. The in vitro bioactivity of the polyelectrolyte film-coated implants was assessed using the alkaline phosphatase assay. BMP-2-coated TA6V and PEEK implants with a total dose of 9.3 µg of BMP-2 were inserted into the femoral condyles of New Zealand white rabbits and compared to uncoated implants. Rabbits were sacrificed 4 and 8 weeks after implantation. Histomorphometric analyses on TA6V and PEEK implants and microcomputed tomography on PEEK implants revealed that the bone-to-implant contact and bone area around the implants were significantly lower for the BMP-2-coated implants than for the bare implants. This was confirmed by scanning electron microscopy imaging. This difference was more pronounced at 4 weeks in comparison to the 8-week time point. However, bone growth inside the hexagonal upper hollow cavity of the screws was higher in the case of the BMP-2 coated implants. Overall, this study shows that a high dose of BMP-2 leads to localized and temporary bone impairment, and that the dose of BMP-2 delivered at the surface of an implant needs to be carefully optimized. PMID:26965394

  4. A Long-Acting BMP-2 Release System Based on Poly(3-hydroxybutyrate) Nanoparticles Modified by Amphiphilic Phospholipid for Osteogenic Differentiation

    Science.gov (United States)

    Peng, Xiaochun; Chen, Yunsu; Li, Yamin; Wang, Yiming

    2016-01-01

    We explored a novel poly(3-hydroxybutyrate) (PHB) nanoparticle loaded with hydrophilic recombinant human BMP-2 with amphiphilic phospholipid (BPC-PHB NP) for a rapid-acting and long-acting delivery system of BMP-2 for osteogenic differentiation. The BPC-PHB NPs were prepared by a solvent evaporation method and showed a spherical particle with a mean particle size of 253.4 nm, mean zeta potential of −22.42 mV, and high entrapment efficiency of 77.18%, respectively. For BPC-PHB NPs, a short initial burst release of BMP-2 from NPs in 24 h was found and it has steadily risen to reach about 80% in 20 days for in vitro test. BPC-PHB NPs significantly reduced the burst release of BMP-2, as compared to that of PHB NPs loading BMP-2 without PL (B-PHB NPs). BPC-PHB NPs maintained the content of BMP-2 for a long-term osteogenic differentiation. The OCT-1 cells with BPC-PHB NPs have high ALP activity in comparison with others. The gene markers for osteogenic differentiation were significantly upregulated for sample with BPC-PHB NPs, implying that BPC-PHB NPs can be used as a rapid-acting and long-acting BMP-2 delivery system for osteogenic differentiation. PMID:27379249

  5. Injectable perlecan domain 1-hyaluronan microgels potentiate the cartilage repair effect of BMP2 in a murine model of early osteoarthritis

    International Nuclear Information System (INIS)

    Srinivasan, Padma P; McCoy, Sarah Y; Yang Weidong; Farach-Carson, Mary C; Kirn-Safran, Catherine B; Jha, Amit K; Jia Xinqiao

    2012-01-01

    The goal of this study was to use bioengineered injectable microgels to enhance the action of bone morphogenetic protein 2 (BMP2) and stimulate cartilage matrix repair in a reversible animal model of osteoarthritis (OA). A module of perlecan (PlnD1) bearing heparan sulfate (HS) chains was covalently immobilized to hyaluronic acid (HA) microgels for the controlled release of BMP2 in vivo. Articular cartilage damage was induced in mice using a reversible model of experimental OA and was treated by intra-articular injection of PlnD1-HA particles with BMP2 bound to HS. Control injections consisted of BMP2-free PlnD1-HA particles, HA particles, free BMP2 or saline. Knees dissected following these injections were analyzed using histological, immunostaining and gene expression approaches. Our results show that knees treated with PlnD1-HA/BMP2 had lesser OA-like damage compared to control knees. In addition, the PlnD1-HA/BMP2-treated knees had higher mRNA levels encoding for type II collagen, proteoglycans and xylosyltransferase 1, a rate-limiting anabolic enzyme involved in the biosynthesis of glycosaminoglycan chains, relative to control knees (PlnD1-HA). This finding was paralleled by enhanced levels of aggrecan in the articular cartilage of PlnD1-HA/BMP2-treated knees. Additionally, decreases in the mRNA levels encoding for cartilage-degrading enzymes and type X collagen were seen relative to controls. In conclusion, PlnD1-HA microgels constitute a formulation improvement compared to HA for efficient in vivo delivery and stimulation of proteoglycan and cartilage matrix synthesis in mouse articular cartilage. Ultimately, PlnD1-HA/BMP2 may serve as an injectable therapeutic agent for slowing or inhibiting the onset of OA after knee injury.

  6. Gallic acid inhibits vascular calcification through the blockade of BMP2-Smad1/5/8 signaling pathway.

    Science.gov (United States)

    Kee, Hae Jin; Cho, Soo-Na; Kim, Gwi Ran; Choi, Sin Young; Ryu, Yuhee; Kim, In Kyeom; Hong, Young Joon; Park, Hyung Wook; Ahn, Youngkeun; Cho, Jeong Gwan; Park, Jong Chun; Jeong, Myung Ho

    2014-11-01

    Vascular calcification is associated with increased risk of morbidity and mortality in patients with cardiovascular diseases, chronic kidney diseases, and diabetes. Gallic acid, a natural compound found in gallnut and green tea, is known to be antifungal, antioxidant, and anticancer. Here we investigated the effect of gallic acid on vascular smooth muscle cell (VSMC) calcification and the underlying mechanism. Gallic acid inhibited inorganic phosphate-induced osteoblast differentiation markers as well as calcification phenotypes (as determined by calcium deposition, Alizarin Red, and Von Kossa staining). Knockdown of BMP2 or Noggin blocked phosphate-induced calcification. Gallic acid suppressed phosphorylation of Smad1/5/8 protein induced by inorganic phosphate. Taken together, we suggest that gallic acid acts as a novel therapeutic agent of vascular calcification by mediating BMP2-Smad1/5/8 signaling pathway. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Regulation of Msx-1, Msx-2, Bmp-2 and Bmp-4 during foetal and postnatal mammary gland development.

    Science.gov (United States)

    Phippard, D J; Weber-Hall, S J; Sharpe, P T; Naylor, M S; Jayatalake, H; Maas, R; Woo, I; Roberts-Clark, D; Francis-West, P H; Liu, Y H; Maxson, R; Hill, R E; Dale, T C

    1996-09-01

    Expression of the Msx-1 and Msx-2 homeobox genes have been shown to be coordinately regulated with the Bmp-2 and Bmp-4 ligands in a variety of developing tissues. Here we report that transcripts from all four genes are developmentally regulated during both foetal and postnatal mammary gland development. The location and time-course of the Bmp and Msx expression point to a role for Msx and Bmp gene products in the control of epithelial-mesenchymal interactions. Expression of Msx-2, but not Msx-1, Bmp-2 or Bmp-4 was decreased following ovariectomy, while expression of the human Msx-2 homologue was regulated by 17beta-oestradiol in the MCF-7 breast cancer cell line. The regulation of Msx-2 expression by oestrogen raises the possibility that hormonal regulation of mammary development is mediated through the control of epithelial-mesenchymal interactions.

  8. E. coli-Produced BMP-2 as a Chemopreventive Strategy for Colon Cancer: A Proof-of-Concept Study

    Directory of Open Access Journals (Sweden)

    Saravanan Yuvaraj

    2012-01-01

    Full Text Available Colon cancer is a serious health problem, and novel preventive and therapeutical avenues are urgently called for. Delivery of proteins with anticancer activity through genetically modified bacteria provides an interesting, potentially specific, economic and effective approach here. Interestingly, bone morphogenetic protein 2 (BMP-2 is an important and powerful tumour suppressor in the colon and is thus an attractive candidate protein for delivery through genetically modified bacteria. It has not been shown, however, that BMP production in the bacterial context is effective on colon cancer cells. Here we demonstrate that transforming E. coli with a cDNA encoding an ileal-derived mature human BMP-2 induces effective apoptosis in an in vitro model system for colorectal cancer, whereas the maternal organism was not effective in this respect. Furthermore, these effects were sensitive to cotreatment with the BMP inhibitor Noggin. We propose that prevention and treatment of colorectal cancer using transgenic bacteria is feasible.

  9. Effect of implantation of biodegradable magnesium alloy on BMP-2 expression in bone of ovariectomized osteoporosis rats

    International Nuclear Information System (INIS)

    Guo, Yue; Ren, Ling; Liu, Chang; Yuan, Yajiang; Lin, Xiao; Tan, Lili; Chen, Shurui; Yang, Ke; Mei, Xifan

    2013-01-01

    The study was focused on the implantation of a biodegradable AZ31 magnesium alloy into the femoral periosteal of the osteoporosis modeled rats. The experimental results showed that after 4 weeks implantation of AZ31 alloy in the osteoporosis modeled rats, the expression of BMP-2 in bone tissues of the rats was much enhanced, even higher than the control group, which should promote the bone formation and be beneficial for reducing the harmful effect of osteoporosis. Results of HE stains showed that the implantation of AZ31 alloy did not have obvious pathological changes on both the liver and kidney of the animal. - Highlights: • Mg alloy greatly increased expression of BMP-2 in osteoporosis modeled rat bone. • Mg alloy showed good biological safety. • Mg alloy is beneficial for reducing the symptom of osteoporosis

  10. The Effects of rhBMP-2 Used for Spinal Fusion on Spinal Cord Pathology After Traumatic Injury

    Science.gov (United States)

    2009-07-29

    1219-1224; discussion 1225. Basso DM , Beattie MS, Bresnahan JC (1995) A sensitive and reliable locomotor rating scale for open field testing in rats...usage of rhBMP-2 in the anterior cervical spine. Spine 31:2813-2819. Stuesse SL, Crisp T, McBurney DL, Schechter JB, Lovell JA, Cruce WL (2001...250-256. Stuesse SL, Crisp T, McBurney DL, Schechter JB, Lovell JA, Cruce WL (2001) Neuropathic pain in aged rats: behavioral responses and

  11. Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features.

    Science.gov (United States)

    Lu, Zhiwei; Huangfu, Changxin; Wang, Yanying; Ge, Hongwei; Yao, Yao; Zou, Ping; Wang, Guangtu; He, Hua; Rao, Hanbing

    2015-01-01

    The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer-Emmett-Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g(-1), respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Repair of rabbit radial bone defects using true bone ceramics combined with BMP-2-related peptide and type I collagen

    International Nuclear Information System (INIS)

    Li Jingfeng; Lin Zhenyu; Zheng Qixin; Guo Xiaodong; Lan Shenghui; Liu Sunan; Yang Shuhua

    2010-01-01

    An ideal bone graft material is the one characterized with good biocompatibility, biodegradation, osteoconductivity and osteoinductivity. In this study, a novel synthetic BMP-2-related peptide (designated P24) corresponding to residues of the knuckle epitope of BMP-2 was introduced into a biomimetic scaffold based on sintered bovine bone or true bone ceramics (TBC) and type I collagen (TBC/collagen I) using a simulated body fluid (SBF). Hydroxylapatite crystal mineralization with a Ca/P molar ratio of 1.63 was observed on the surface of P24/TBC/collagen I composite by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. Cell adhesion rate evaluation of bone marrow stromal cells (BMSCs) seeded on materials in vitro showed that the percentage of cells attached to P24/TBC/collagen I composite was significantly higher than that of the TBC/collagen I composite. A 10 mm unilateral segmental bone defect was created in the radius of New Zealand white rabbits and randomly implanted with three groups of biomaterials (Group A: P24/TBC/collagen I composite; Group B: TBC/collagen I composite and Group C: TBC alone). Based on radiographic evaluation and histological examination, the implants of P24/TBC/collagen I composite significantly stimulated bone growth, thereby confirming the enhanced rate of bone healing compared with that of TBC/collagen I composite and TBC alone. It was concluded that BMP-2-related peptide P24 could induce nucleation of calcium phosphate crystals on the surface of TBC/collagen I composite. The TBC/collagen I composite loaded with the synthetic BMP-2-related peptide is a promising scaffold biomaterial for bone tissue engineering.

  13. BMP2 induced osteogenic differentiation of human umbilical cord stem cells in a peptide-based hydrogel scaffold

    Science.gov (United States)

    Lakshmana, Shruthi M.

    Craniofacial tissue loss due to traumatic injuries and congenital defects is a major clinical problem around the world. Cleft palate is the second most common congenital malformation in the United States occurring with an incidence of 1 in 700. Some of the problems associated with this defect are feeding difficulties, speech abnormalities and dentofacial anomalies. Current treatment protocol offers repeated surgeries with extended healing time. Our long-term goal is to regenerate bone in the palatal region using tissue-engineering approaches. Bone tissue engineering utilizes osteogenic cells, osteoconductive scaffolds and osteoinductive signals. Mesenchymal stem cells derived from human umbilical cord (HUMSCs) are highly proliferative with the ability to differentiate into osteogenic precursor cells. The primary objective of the study was to characterize HUMSCs and culture them in a 3D hydrogel scaffold and investigate their osteogenic potential. PuraMatrix(TM) is an injectable 3D nanofiber scaffold capable of self-assembly when exposed to physiologic conditions. Our second objective was to investigate the effect of Bone Morphogenic Protein 2 (BMP2) in enhancing the osteogenic differentiation of HUMSCs encapsulated in PuraMatrix(TM). We isolated cells isolated from Wharton's Jelly region of the umbilical cord obtained from NDRI (New York, NY). Isolated cells satisfied the minimal criteria for mesenchymal stem cells (MSCs) as defined by International Society of Cell Therapy in terms of plastic adherence, fibroblastic phenotype, surface marker expression and osteogenic differentiation. Flow Cytometry analysis showed that cells were positive for CD73, CD90 and CD105 while negative for hematopoietic marker CD34. Alkaline phosphatase activity (ALP) of HUMSCs showed peak activity at 2 weeks (p<0.05). Cells were encapsulated in 0.2% PuraMatrix(TM) at cell densities of 10x104, 20x104, 40x10 4 and 80x104. Cell viability with WST and proliferation with Live-Dead cell assays

  14. MRI of transforaminal lumbar interbody fusion: imaging appearance with and without the use of human recombinant bone morphogenetic protein-2 (rhBMP-2)

    Energy Technology Data Exchange (ETDEWEB)

    Fox, Michael G.; Goldberg, Judd M.; Gaskin, Cree M.; Barr, Michelle S.; Alford, Bennett [University of Virginia, Department of Radiology and Medical Imaging, Charlottesville, VA (United States); Patrie, James T. [University of Virginia, Department of Public Health Sciences, Charlottesville, VA (United States); Shen, Francis H. [University of Virginia, Department of Orthopedic Surgery, Charlottesville, VA (United States)

    2014-09-15

    To describe the vertebral endplate and intervertebral disc space MRI appearance following TLIF, with and without the use of rhBMP-2, and to determine if the appearance is concerning for discitis/osteomyelitis. After institutional review board approval, 116 TLIF assessments performed on 75 patients with rhBMP-2 were retrospectively and independently reviewed by five radiologists and compared to 73 TLIF assessments performed on 45 patients without rhBMP-2. MRIs were evaluated for endplate signal, disc space enhancement, disc space fluid, and abnormal paraspinal soft tissue. Endplate edema-like signal was reported when T1-weighted hypointensity, T2-weighted hyperintensity, and endplate enhancement were present. Subjective concern for discitis/osteomyelitis on MRI was graded on a five-point scale. Generalized estimating equation binomial regression model analysis was performed with findings correlated with rhBMP-2 use, TLIF level, graft type, and days between TLIF and MRI. The rhBMP-2 group demonstrated endplate edema-like signal (OR 5.66; 95 % CI [1.58, 20.24], p = 0.008) and disc space enhancement (OR 2.40; 95 % CI [1.20, 4.80], p = 0.013) more often after adjusting for the TLIF level, graft type, and the number of days following TLIF. Both groups had a similar temporal distribution for endplate edema-like signal but disc space enhancement peaked earlier in the rhBMP-2 group. Disc space fluid was only present in the rhBMP-2 group. Neither group demonstrated abnormal paraspinal soft tissue and discitis/osteomyelitis was not considered likely in any patient. Endplate edema-like signal and disc space enhancement were significantly more frequent and disc space enhancement developed more rapidly following TLIF when rhBMP-2 was utilized. The concern for discitis/osteomyelitis was similar and minimal in both groups. (orig.)

  15. Metastatic function of BMP-2 in gastric cancer cells: The role of PI3K/AKT, MAPK, the NF-{kappa}B pathway, and MMP-9 expression

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Myoung Hee [Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of); Oh, Sang Cheul [Division of Oncology/Hematology, Department of Internal Medicine, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of); Lee, Hyun Joo [Department of Pathology, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of); Kang, Han Na; Kim, Jung Lim [Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of); Kim, Jun Suk [Division of Oncology/Hematology, Department of Internal Medicine, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of); Yoo, Young A., E-mail: ydanbi@korea.ac.kr [Brain Korea 21 Program for Biomedical Science, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of)

    2011-07-15

    Bone morphogenetic proteins (BMPs) have been implicated in tumorigenesis and metastatic progression in various types of cancer cells, but the role and cellular mechanism in the invasive phenotype of gastric cancer cells is not known. Herein, we determined the roles of phosphoinositide 3-kinase (PI3K)/AKT, extracellular signal-regulated protein kinase (ERK), nuclear factor (NF)-{kappa}B, and matrix metalloproteinase (MMP) expression in BMP-2-mediated metastatic function in gastric cancer. We found that stimulation of BMP-2 in gastric cancer cells enhanced the phosphorylation of AKT and ERK. Accompanying activation of AKT and ERK kinase, BMP-2 also enhanced phosphorylation/degradation of I{kappa}B{alpha} and the nuclear translocation/activation of NF-{kappa}B. Interestingly, blockade of PI3K/AKT and ERK signaling using LY294002 and PD98059, respectively, significantly inhibited BMP-2-induced motility and invasiveness in association with the activation of NF-{kappa}B. Furthermore, BMP-2-induced MMP-9 expression and enzymatic activity was also significantly blocked by treatment with PI3K/AKT, ERK, or NF-{kappa}B inhibitors. Immunohistochemistry staining of 178 gastric tumor biopsies indicated that expression of BMP-2 and MMP-9 had a significant positive correlation with lymph node metastasis and a poor prognosis. These results indicate that the BMP-2 signaling pathway enhances tumor metastasis in gastric cancer by sequential activation of the PI3K/AKT or MAPK pathway followed by the induction of NF-{kappa}B and MMP-9 activity, indicating that BMP-2 has the potential to be a therapeutic molecular target to decrease metastasis.

  16. Colloid, adhesive and release properties of nanoparticular ternary complexes between cationic and anionic polysaccharides and basic proteins like bone morphogenetic protein BMP-2.

    Science.gov (United States)

    Petzold, R; Vehlow, D; Urban, B; Grab, A L; Cavalcanti-Adam, E A; Alt, V; Müller, M

    2017-03-01

    Herein we describe an interfacial local drug delivery system for bone morphogenetic protein 2 (BMP-2) based on coatings of polyelectrolyte complex (PEC) nanoparticles (NP). The application horizon is the functionalization of bone substituting materials (BSM) used for the therapy of systemic bone diseases. Nanoparticular ternary complexes of cationic and anionic polysaccharides and BMP-2 or two further model proteins, respectively, were prepared in dependence of the molar mixing ratio, pH value and of the cationic polysaccharide. As further proteins chymotrypsin (CHY) and papain (PAP) were selected, which served as model proteins for BMP-2 due to similar isoelectric points and molecular weights. As charged polysaccharides ethylenediamine modified cellulose (EDAC) and trimethylammonium modified cellulose (PQ10) were combined with cellulose sulphatesulfate (CS). Mixing diluted cationic and anionic polysaccharide and protein solutions according to a slight either anionic or cationic excess charge colloidal ternary dispersions formed, which were cast onto germanium model substrates by water evaporation. Dynamic light scattering (DLS) demonstrated, that these dispersions were colloidally stable for at least one week. Fourier Transform Infrared (FTIR) showed, that the cast protein loaded PEC NP coatings were irreversibly adhesive at the model substrate in contact to HEPES buffer and solely CHY, PAP and BMP-2 were released within long-term time scale. Advantageously, out of the three proteins BMP-2 showed the smallest initial burst and the slowest release kinetics and around 25% of the initial BMP-2 content were released within 14days. Released BMP-2 showed significant activity in the myoblast cells indicating the ability to regulate the formation of new bone. Therefore, BMP-2 loaded PEC NP are suggested as novel promising tool for the functionalization of BSM used for the therapy of systemic bone diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Post-transcriptional Mechanisms Contribute Little to Phenotypic Variation in Snake Venoms.

    Science.gov (United States)

    Rokyta, Darin R; Margres, Mark J; Calvin, Kate

    2015-09-09

    Protein expression is a major link in the genotype-phenotype relationship, and processes affecting protein abundances, such as rates of transcription and translation, could contribute to phenotypic evolution if they generate heritable variation. Recent work has suggested that mRNA abundances do not accurately predict final protein abundances, which would imply that post-transcriptional regulatory processes contribute significantly to phenotypes. Post-transcriptional processes also appear to buffer changes in transcriptional patterns as species diverge, suggesting that the transcriptional changes have little or no effect on the phenotypes undergoing study. We tested for concordance between mRNA and protein expression levels in snake venoms by means of mRNA-seq and quantitative mass spectrometry for 11 snakes representing 10 species, six genera, and three families. In contrast to most previous work, we found high correlations between venom gland transcriptomes and venom proteomes for 10 of our 11 comparisons. We tested for protein-level buffering of transcriptional changes during species divergence by comparing the difference between transcript abundance and protein abundance for three pairs of species and one intraspecific pair. We found no evidence for buffering during divergence of our three species pairs but did find evidence for protein-level buffering for our single intraspecific comparison, suggesting that buffering, if present, was a transient phenomenon in venom divergence. Our results demonstrated that post-transcriptional mechanisms did not contribute significantly to phenotypic evolution in venoms and suggest a more prominent and direct role for cis-regulatory evolution in phenotypic variation, particularly for snake venoms. Copyright © 2015 Rokyta et al.

  18. Medium-Term Function of a 3D Printed TCP/HA Structure as a New Osteoconductive Scaffold for Vertical Bone Augmentation: A Simulation by BMP-2 Activation

    Directory of Open Access Journals (Sweden)

    Mira Moussa

    2015-04-01

    Full Text Available Introduction: A 3D-printed construct made of orthogonally layered strands of tricalcium phosphate (TCP and hydroxyapatite has recently become available. The material provides excellent osteoconductivity. We simulated a medium-term experiment in a sheep calvarial model by priming the blocks with BMP-2. Vertical bone growth/maturation and material resorption were evaluated. Materials and methods: Titanium hemispherical caps were filled with either bare- or BMP-2 primed constructs and placed onto the calvaria of adult sheep (n = 8. Histomorphometry was performed after 8 and 16 weeks. Results: After 8 weeks, relative to bare constructs, BMP-2 stimulation led to a two-fold increase in bone volume (Bare: 22% ± 2.1%; BMP-2 primed: 50% ± 3% and a 3-fold decrease in substitute volume (Bare: 47% ± 5%; BMP-2 primed: 18% ± 2%. These rates were still observed at 16 weeks. The new bone grew and matured to a haversian-like structure while the substitute material resorbed via cell- and chemical-mediation. Conclusion: By priming the 3D construct with BMP-2, bone metabolism was physiologically accelerated, that is, enhancing vertical bone growth and maturation as well as material bioresorption. The scaffolding function of the block was maintained, leaving time for the bone to grow and mature to a haversian-like structure. In parallel, the material resorbed via cell-mediated and chemical processes. These promising results must be confirmed in clinical tests.

  19. Functionalization of deproteinized bovine bone with a coating-incorporated depot of BMP-2 renders the material efficiently osteoinductive and suppresses foreign-body reactivity.

    Science.gov (United States)

    Wu, Gang; Hunziker, Ernst B; Zheng, Yuanna; Wismeijer, Daniel; Liu, Yuelian

    2011-12-01

    The repair of critical-sized bony defects remains a challenge in the fields of implantology, maxillofacial surgery and orthopaedics. As an alternative bone-defect filler to autologous bone grafts, deproteinized bovine bone (DBB) is highly osteoconductive and clinically now widely used. However, this product suffers from the disadvantage of not being intrinsically osteoinductive. In the present study, this property was conferred by coating DBB with a layer of calcium phosphate into which bone morphogenetic protein 2 (BMP-2) was incorporated. Granules of DBB bearing a coating-incorporated depot of BMP-2--together with the appropriate controls (DBB bearing a coating but no BMP-2; uncoated DBB bearing adsorbed BMP-2; uncoated DBB bearing no BMP-2)--were implanted subcutaneously in rats. Five weeks later, the implants were withdrawn for a histomorphometric analysis of the volume densities of (i) bone, (ii) bone marrow, (iii) foreign-body giant cells and (iv) fibrous capsular tissue. Parameters (i) and (ii) were highest, whilst parameters (iii) and (iv) were lowest in association with DBB bearing a coating-incorporated depot of BMP-2. Hence, this mode of functionalization not only confers DBB with the property of osteoinductivity but also improves its biocompatibility--thus dually enhancing its clinical potential in the repair of bony defects. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Adipose-derived stem cells and BMP-2 delivery in chitosan-based 3D constructs to enhance bone regeneration in a rat mandibular defect model.

    Science.gov (United States)

    Fan, Jiabing; Park, Hyejin; Lee, Matthew K; Bezouglaia, Olga; Fartash, Armita; Kim, Jinku; Aghaloo, Tara; Lee, Min

    2014-08-01

    Reconstructing segmental mandiblular defects remains a challenge in the clinic. Tissue engineering strategies provide an alternative option to resolve this problem. The objective of the present study was to determine the effects of adipose-derived stem cells (ASCs) and bone morphogenetic proteins-2 (BMP-2) in three-dimensional (3D) scaffolds on mandibular repair in a small animal model. Noggin expression levels in ASCs were downregulated by a lentiviral short hairpin RNA strategy to enhance ASC osteogenesis (ASCs(Nog-)). Chitosan (CH) and chondroitin sulfate (CS), natural polysaccharides, were fabricated into 3D porous scaffolds, which were further modified with apatite coatings for enhanced cellular responses and efficient delivery of BMP-2. The efficacy of 3D apatite-coated CH/CS scaffolds supplemented with ASCs(Nog-) and BMP-2 were evaluated in a rat critical-sized mandibular defect model. After 8 weeks postimplantation, the scaffolds treated with ASCs(Nog-) and BMP-2 significantly promoted rat mandibular regeneration as demonstrated by micro-computerized tomography, histology, and immunohistochemistry, compared with the groups treated with ASCs(Nog-) or BMP-2 alone. These results suggest that our combinatorial strategy of ASCs(Nog-)+BMP-2 in 3D apatite microenvironments can significantly promote mandibular regeneration, and these may provide a potential tissue engineering approach to repair large bony defects.

  1. RNAi mediates post-transcriptional repression of gene expression in fission yeast Schizosaccharomyces pombe

    International Nuclear Information System (INIS)

    Smialowska, Agata; Djupedal, Ingela; Wang, Jingwen; Kylsten, Per; Swoboda, Peter; Ekwall, Karl

    2014-01-01

    Highlights: • Protein coding genes accumulate anti-sense sRNAs in fission yeast S. pombe. • RNAi represses protein-coding genes in S. pombe. • RNAi-mediated gene repression is post-transcriptional. - Abstract: RNA interference (RNAi) is a gene silencing mechanism conserved from fungi to mammals. Small interfering RNAs are products and mediators of the RNAi pathway and act as specificity factors in recruiting effector complexes. The Schizosaccharomyces pombe genome encodes one of each of the core RNAi proteins, Dicer, Argonaute and RNA-dependent RNA polymerase (dcr1, ago1, rdp1). Even though the function of RNAi in heterochromatin assembly in S. pombe is established, its role in controlling gene expression is elusive. Here, we report the identification of small RNAs mapped anti-sense to protein coding genes in fission yeast. We demonstrate that these genes are up-regulated at the protein level in RNAi mutants, while their mRNA levels are not significantly changed. We show that the repression by RNAi is not a result of heterochromatin formation. Thus, we conclude that RNAi is involved in post-transcriptional gene silencing in S. pombe

  2. Transcriptional and Post-Transcriptional Mechanisms of the Development of Neocortical Lamination

    Directory of Open Access Journals (Sweden)

    Tatiana Popovitchenko

    2017-11-01

    Full Text Available The neocortex is a laminated brain structure that is the seat of higher cognitive capacity and responses, long-term memory, sensory and emotional functions, and voluntary motor behavior. Proper lamination requires that progenitor cells give rise to a neuron, that the immature neuron can migrate away from its mother cell and past other cells, and finally that the immature neuron can take its place and adopt a mature identity characterized by connectivity and gene expression; thus lamination proceeds through three steps: genesis, migration, and maturation. Each neocortical layer contains pyramidal neurons that share specific morphological and molecular characteristics that stem from their prenatal birth date. Transcription factors are dynamic proteins because of the cohort of downstream factors that they regulate. RNA-binding proteins are no less dynamic, and play important roles in every step of mRNA processing. Indeed, recent screens have uncovered post-transcriptional mechanisms as being integral regulatory mechanisms to neocortical development. Here, we summarize major aspects of neocortical laminar development, emphasizing transcriptional and post-transcriptional mechanisms, with the aim of spurring increased understanding and study of its intricacies.

  3. Matrix-immobilized BMP-2 on microcontact printed fibronectin as in vitro tool to study BMP-mediated signaling and cell migration

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    Kristin eHauff

    2015-05-01

    Full Text Available During development, bone morphogenetic proteins (BMPs exert important functions in several tissues by regulating signaling for cell differentiation and migration. In vivo the extracellular matrix (ECM not only provides a support for adherent cells, but also presents a reservoir of growth factors (GFs. Several constituents of the ECM provide adhesive cues, which serve as binding sites for cell transmembrane receptors, such as integrins, which convey adhesion-mediated signaling to the intracellular compartment. Integrins do not function alone but rather crosstalk and cooperate with other receptors, such as GF receptors, in regulating cell responses to extracellular signals. To this, we present here the immobilization of BMP-2 onto cellular fibronectin (cFN, a key protein of the ECM, to investigate their impact on GF-mediated signaling and migration.Following biotinylation, BMP-2 was linked to biotinylated cFN using NeutrAvidin (NA as cross-linker. Characterization with QCM-D and ELISA confirmed the efficient immobilization of BMP-2 on cFN over a period of 24 h.To validate the bioactivity of matrix-immobilized BMP-2 (iBMP-2 we investigated short- and long-term responses of C2C12 myoblasts in comparison to soluble BMP-2 (sBMP-2 or in absence of GFs. Similarly to sBMP-2, iBMP-2 triggered Smad 1/5 phosphorylation and translocation into the nucleus corresponding to the activation of BMP-mediated Smad-dependent pathway. Additionally, successful suppression of myotube formation was observed after six days.We next implemented this approach to fabricate cFN micro patterned stripes by soft lithography. These stripes only allowed cell-surface interaction on the pattern due to passivation of the surface in between, thus serving as platform for studies on directed cell migration. During a 10 h-period, cells showed an increased migratory activity upon BMP-2 exposure.Thus, this versatile tool retains the GF's bioactivity and allows the presentation of ECM

  4. Trehalose maintains bioactivity and promotes sustained release of BMP-2 from lyophilized CDHA scaffolds for enhanced osteogenesis in vitro and in vivo.

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    Jun Zhao

    Full Text Available Calcium phosphate (Ca-P scaffolds have been widely employed as a supportive matrix and delivery system for bone tissue engineering. Previous studies using osteoinductive growth factors loaded Ca-P scaffolds via passive adsorption often experience issues associated with easy inactivation and uncontrolled release. In present study, a new delivery system was fabricated using bone morphogenetic protein-2 (BMP-2 loaded calcium-deficient hydroxyapatite (CDHA scaffold by lyophilization with addition of trehalose. The in vitro osteogenesis effects of this formulation were compared with lyophilized BMP-2/CDHA construct without trehalose and absorbed BMP-2/CDHA constructs with or without trehalose. The release characteristics and alkaline phosphatase (ALP activity analyses showed that addition of trehalose could sufficiently protect BMP-2 bioactivity during lyophilization and achieve sustained BMP-2 release from lyophilized CDHA construct in vitro and in vivo. However, absorbed BMP-2/CDHA constructs with or without trehalose showed similar BMP-2 bioactivity and presented a burst release. Quantitative real-time PCR (RT-qPCR and enzyme-linked immunosorbent assay (ELISA demonstrated that lyophilized BMP-2/CDHA construct with trehalose (lyo-tre-BMP-2 promoted osteogenic differentiation of bone marrow stromal cells (bMSCs significantly and this formulation could preserve over 70% protein bioactivity after 5 weeks storage at 25°C. Micro-computed tomography, histological and fluorescent labeling analyses further demonstrated that lyo-tre-BMP-2 formulation combined with bMSCs led to the most percentage of new bone volume (38.79% ± 5.32% and area (40.71% ± 7.14% as well as the most percentage of fluorochrome stained bone area (alizarin red S: 2.64% ± 0.44%, calcein: 6.08% ± 1.37% and mineral apposition rate (4.13 ± 0.62 µm/day in critical-sized rat cranial defects healing. Biomechanical tests also indicated the maximum stiffness (118.17 ± 15.02 Mpa and

  5. Deproteinized bovine bone functionalized with the slow delivery of BMP-2 for the repair of critical-sized bone defects in sheep.

    Science.gov (United States)

    Liu, Tie; Wu, Gang; Wismeijer, Daniel; Gu, Zhiyuan; Liu, Yuelian

    2013-09-01

    As an alternative to an autologous bone graft, deproteinized bovine bone (DBB) is widely used in the clinical dentistry. Although DBB provides an osteoconductive scaffold, it is not capable of enhancing bone regeneration because it is not osteoinductive. In order to render DBB osteoinductive, bone morphogenetic protein 2 (BMP-2) has previously been incorporated into a three dimensional reservoir (a biomimetic calcium phosphate coating) on DBB, which effectively promoted the osteogenic response by the slow delivery of BMP-2. The aim of this study was to investigate the therapeutic effectiveness of such coating on the DBB granules in repairing a large cylindrical bone defect (8 mm diameter, 13 mm depth) in sheep. Eight groups were randomly assigned to the bone defects: (i) no graft material; (ii) autologous bone; (iii) DBB only; (iv) DBB mixed with autologous bone; (v) DBB bearing adsorbed BMP-2; (vi) DBB bearing a coating but no BMP-2; (vii) DBB bearing a coating with adsorbed BMP-2; and (viii) DBB bearing a coating-incorporated depot of BMP-2. 4 and 8 weeks after implantation, samples were withdrawn for a histological and a histomorphometric analysis. Histological results confirmed the excellent biocompatibility and osteoconductivity of all the grafts tested. At 4 weeks, DBB mixed with autologous bone or functionalized with coating-incorporated BMP-2 showed more newly-formed bone than the other groups with DBB. At 8 weeks, the volume of newly-formed bone around DBB that bore a coating-incorporated depot of BMP-2 was greatest among the groups with DBB, and was comparable to the autologous bone group. The use of autologous bone and BMP-2 resulted in more bone marrow formation. Multinucleated giant cells were observed in the resorption process around DBB, whereas histomorphometric analysis revealed no significant degradation of DBB. In conclusion, it was shown that incorporating BMP-2 into the calcium phosphate coating of DBB induced strong bone formation around DBB

  6. Evaluation of bioactive glass incorporated poly(caprolactone)-poly(vinyl alcohol) matrix and the effect of BMP-2 modification

    Energy Technology Data Exchange (ETDEWEB)

    Keothongkham, Khamsone [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Charoenphandhu, Narattaphol [Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10900 (Thailand); Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10900 (Thailand); Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170 (Thailand); Thongbunchoo, Jirawan; Suntornsaratoon, Panan; Krishnamra, Nateetip [Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok 10900 (Thailand); Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10900 (Thailand); Tang, I-Ming [Department of Materials Science Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Pon-On, Weeraphat, E-mail: fsciwpp@ku.ac.th [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand)

    2017-05-01

    Composite materials having mechanical and biological properties similar to those of human bones are needed for bone regeneration and repair. In the present study, composites were made by incorporating bioactive glass (BG) into polycaprolactone (PCL)-polyvinyl alcohol (PVA) (PCLPVA) matrix. Composites with different BG contents of 10, 25 and 50 wt% were fabricated by an in-situ blending method. Physicochemical properties measurements found that the composite with 50 wt% BG in the PCLPVA organic matrix exhibited the best mechanical properties (compressive strength and compressive young's modulus up to 32.26 MPa and 530.91 MPa, respectively). We investigated the effects of the BG content on cell adhesion, proliferation and osteogenic activity of UMR-106 cells grown on the scaffolds using in vitro cell culture assay. The composite scaffolds having 25 wt% BG showed a significant increase in their cell adhesion capability and a faster cell proliferation. They also exhibited cell adhesion and spreading morphology after only 5 days of culturing. For these reasons, we chose to attach the bone morphogenetic protein (BMP)-2 to this composite. The resulting composite (labeled BMP-2-loaded PCLPVABG25) showed significant improvement in the UMR-106 cells adhesion, in the enhancement in osteogenic differentiation and osteoinductivity of this composite. - Highlights: • Preparation of PCLPVABGx composite scaffolds and their physical properties. • Mechanical properties could be adjusted by controlling BG contents in PCLPVA matrix. • In vitro cell availability tests confirmed the osteoblast grow on the PCLPVABGx composite scaffolds surface. • Upon the BMP-2-loaded PCLPVABG25 scaffolds can enhance cell attachment and significantly improved osteogenicity.

  7. Controlled Retention of BMP-2-Derived Peptide on Nanofibers Based on Mussel-Inspired Adhesion for Bone Formation.

    Science.gov (United States)

    Lee, Jinkyu; Perikamana, Sajeesh Kumar Madhurakkat; Ahmad, Taufiq; Lee, Min Suk; Yang, Hee Seok; Kim, Do-Gyoon; Kim, Kyobum; Kwon, Bosun; Shin, Heungsoo

    2017-04-01

    Although bone morphogenetic protein-2 (BMP-2) has been frequently used to stimulate bone formation, it has several side effects to be addressed, including the difficulty in optimization of clinically relevant doses and unwanted induction of cancerous signaling processes. In this study, an osteogenic peptide (OP) derived from BMP-2 was investigated as a substitute for BMP-2. In vitro studies showed that OP was able to enhance the osteogenic differentiation and mineralization of human mesenchymal stem cells (hMSCs). The peptides were then conjugated onto biocompatible poly-ι-lactide electrospun nanofibers through polydopamine chemistry. Surface chemical analysis proved that more than 80% of the peptides were stably retained on the nanofiber surface after 8 h of polydopamine coating during at least 28 days, and the amount of peptides that was retained increased depending on the polydopamine coating time. For instance, about 65% of the peptides were retained on nanofibers after 4 h of polydopamine coating. Also, a relatively small dose of peptides could effectively induce bone formation in in vivo critical-sized defects on the calvarial bones of mice. More than 50.4% ± 16.9% of newly formed bone was filled within the defect after treatment with only 10.5 ± 0.6 μg of peptides. Moreover, these groups had similar elastic moduli and contact hardnesses with host bone. Taken together, our results suggest that polydopamine-mediated OP immobilized on nanofibers can modulate the retention of relatively short lengths of peptides, which might make this an effective therapeutic remedy to guide bone regeneration using a relatively small amount of peptides.

  8. Surface Modification of Titanium with BMP-2/GDF-5 by a Heparin Linker and Its Efficacy as a Dental Implant

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    Dae Hyeok Yang

    2017-01-01

    Full Text Available In this study, we prepared human bone morphogenetic protein-2 (hBMP-2/human growth and differentiation factor-5 (hGDF-5-coated titanium (Ti disc and screw types for controlled release of the growth factors (GFs. The two growth factors were coated onto Ti with a smooth surface using their specific interaction with heparin, because they have heparin binding sites in their molecular structures. Efficacy of the two growth factor-coated Ti for enhancement of bone formation and osseointegration was compared to pristine Ti, and hBMP-2- and hGDF-5-coated Ti in vivo. The surface chemical composition, surface morphology, and wettability characteristics of the metal samples were determined by X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM, and contact angle measurement, respectively. The initial burst of hBMP-2, hGDF-5, and their combination, occurred within one day of the release study, resulting in 12.5%, 4.5%, and 13.5%/3.2%, and then there was a sustained, even release of these two growth factors from the coated metal for 30 days. In vitro tests revealed that MC3T3-E1 cells cultured on the two growth factor-coated Ti had a higher proliferation rate and a higher activity for alkaline phosphatase (ALP, which led to a larger amount of calcium deposition and larger expressions of type I collagen (COL 1, ALP, and osteocalcin (OCN mRNAs. In vivo animal tests using ten white New Zealand rabbits showed that the two growth factor-coated Ti enhanced bone formation and osseointegration at the interface between the implants and host bone. In addition, histological evaluation showed that bone remodeling, including bone formation by osteoblasts and bone resorption by osteoclasts, actively occurred between the two growth factor-coated Ti and host bone. Consequently, it is suggested that Ti surface modification with the combination of hBMP-2 and hGDF-5 for the two growth factor-coated Ti implants can improve the clinical properties of

  9. Off-label use of rhBMP-2 as bone regeneration strategies in mandibular ameloblastoma unicystic.

    Science.gov (United States)

    Silva, Henrique Celestino Lima E; Cheim, Adonai Peixoto; Moreno, Roberto; Miranda, Sérgio Luis de

    2017-01-01

    Jawbone reconstruction after tumor resection is one of the most challenging clinical tasks for maxillofacial surgeons. Osteogenic, osteoinductive, osteoconductive and non-antigenic properties of autogenous bone place this bone as the gold standard for solving problems of bone availability. However, the need for a second surgical site to harvest the bone graft increases significantly both the cost and the morbidity associated with the reconstructive procedures. Bone grafting gained an important tool with the discovery of bone morphogenetic proteins in 1960. Benefit of obtaining functional and real bone matrix without need of second surgical site seems to be the great advantage of use bone morphogenetic proteins. This study analyzed the use of rhBMP-2 in unicystic ameloblastoma of the mandible, detailing its structure, mechanisms of cell signaling and biological efficacy, in addition to present possible advantages and disadvantages of clinical use of rhBMP-2 as bone regeneration strategy. RESUMO A reconstrução óssea dos maxilares após ressecções tumorais é uma das tarefas mais difíceis para o cirurgião maxilofacial. As propriedades osteogênicas, osteoindutoras, osteocondutoras e não antigênicas do osso autógeno o colocam como o padrão-ouro para a solução de problemas de disponibilidade óssea. Entretanto a coleta do enxerto ósseo necessita de um segundo sítio cirúrgico, aumentando significativamente o custo e a morbidade associados ao procedimento reconstrutivo. A enxertia óssea ganhou uma excelente ferramenta com a descoberta das proteínas ósseas morfogenéticas na década de 1960. O benefício da obtenção de matriz óssea verdadeira e funcional, sem a necessidade de um segundo sítio cirúrgico, parece ser a grande vantagem do uso das proteínas ósseas morfogenéticas. Neste contexto, o objetivo deste estudo foi analisar a utilização da rhBMP-2 na regeneração óssea de ameloblastoma mandibular unicístico, detalhando sua estrutura, seus

  10. Enhancement of Tendon–Bone Healing for Anterior Cruciate Ligament (ACL Reconstruction Using Bone Marrow-Derived Mesenchymal Stem Cells Infected with BMP-2

    Directory of Open Access Journals (Sweden)

    Shiyi Chen

    2012-10-01

    Full Text Available At present, due to the growing attention focused on the issue of tendon–bone healing, we carried out an animal study of the use of genetic intervention combined with cell transplantation for the promotion of this process. Here, the efficacy of bone marrow stromal cells infected with bone morphogenetic protein-2 (BMP-2 on tendon–bone healing was determined. A eukaryotic expression vector containing the BMP-2 gene was constructed and bone marrow-derived mesenchymal stem cells (bMSCs were infected with a lentivirus. Next, we examined the viability of the infected cells and the mRNA and protein levels of BMP-2-infected bMSCs. Gastrocnemius tendons, gastrocnemius tendons wrapped by bMSCs infected with the control virus (bMSCs+Lv-Control, and gastrocnemius tendons wrapped by bMSCs infected with the recombinant BMP-2 virus (bMSCs+Lv-BMP-2 were used to reconstruct the anterior cruciate ligament (ACL in New Zealand white rabbits. Specimens from each group were harvested four and eight weeks postoperatively and evaluated using biomechanical and histological methods. The bMSCs were infected with the lentivirus at an efficiency close to 100%. The BMP-2 mRNA and protein levels in bMSCs were significantly increased after lentiviral infection. The bMSCs and BMP-2-infected bMSCs on the gastrocnemius tendon improved the biomechanical properties of the graft in the bone tunnel; specifically, bMSCs infected with BMP-2 had a positive effect on tendon–bone healing. In the four-week and eight-week groups, bMSCs+Lv-BMP-2 group exhibited significantly higher maximum loads of 29.3 ± 7.4 N and 45.5 ± 11.9 N, respectively, compared with the control group (19.9 ± 6.4 N and 21.9 ± 4.9 N (P = 0.041 and P = 0.001, respectively. In the eight-week groups, the stiffness of the bMSCs+Lv-BMP-2 group (32.5 ± 7.3 was significantly higher than that of the bMSCs+Lv-Control group (22.8 ± 7.4 or control groups (12.4 ± 6.0 (p = 0.036 and 0.001, respectively. Based on the

  11. TNF-α Upregulates Expression of BMP-2 and BMP-3 Genes in the Rat Dental Follicle – Implications for Tooth Eruption

    Science.gov (United States)

    Yao, Shaomian; Prpic, Veronica; Pan, Fenghui; Wise, Gary E.

    2011-01-01

    The dental follicle appears to regulate both the alveolar bone resorption and bone formation needed for tooth eruption. Tumor necrosis factor-alpha ( TNF-α) gene expression is maximally upregulated at postnatal day 9 in the rat dental follicle of the 1st mandibular molar, a time that correlates with rapid bone growth at the base of the tooth crypt, as well as a minor burst of osteoclastogenesis. TNF-α expression is correlated with the expression of bone morphogenetic protein-2 (BMP-2), a molecule expressed in the dental follicle that can promote bone formation. Because BMP-2 signaling may be augmented by bone morphogenetic protein-3 (BMP-3), it was the objective of this study to determine 1) if the dental follicle expresses BMP-3 and 2) if TNF-α stimulates the dental follicle cells to express BMP-2 and BMP-3. Dental follicles were collected from different postnatal ages of rat pups. Dental follicle cells were incubated with TNF-α to study its dosage and time-course effects on gene expression of BMP-2 and BMP-3, as determined by real-time RT-PCR. Next, immunostaining was conducted to confirm if the protein was synthesized and ELISA of the conditioned medium was conducted to determine if BMP-2 was secreted. We found that BMP-3 expression is correlated with the expression of TNF-α in the dental follicle and TNF-α significantly increased BMP-2 and BMP-3 expression in vitro. Immunostaining and ELISA showed that BMP-2 and BMP-3 were synthesized and secreted. This study suggests that TNF-α can upregulate the expression of bone formation genes that may be needed for tooth eruption. PMID:20067418

  12. Influence of Mussel-Derived Bioactive BMP-2-Decorated PLA on MSC Behavior in Vitro and Verification with Osteogenicity at Ectopic Sites in Vivo.

    Science.gov (United States)

    Chen, Zhuoyue; Zhang, Zhen; Feng, Juantao; Guo, Yayuan; Yu, Yuan; Cui, Jihong; Li, Hongmin; Shang, Lijun

    2018-04-11

    Osteoinductive activity of the implant in bone healing and regeneration is still a challenging research topic. Therapeutic application of recombinant human bone morphogenetic protein-2 (BMP-2) is a promising approach to enhance osteogenesis. However, high dose and uncontrolled burst release of BMP-2 may introduce edema, bone overgrowth, cystlike bone formation, and inflammation. In this study, low-dose BMP-2 of 1 μg was used to design PLA-PD-BMP for functionalization of polylactic acid (PLA) implants via mussel-inspired polydopamine (PD) assist. For the first time, the binding property and efficiency of the PD coating with BMP-2 were directly demonstrated and analyzed using an antigen-antibody reaction. The obtained PLA-PD-BMP surface immobilized with this low BMP-2 dose can endow the implants with abilities of introducing strong stem cell adhesion and enhanced osteogenicity. Furthermore, in vivo osteoinduction of the PLA-PD-BMP-2 scaffolds was confirmed by a rat ectopic bone model, which is marked as the "gold standard" for the evidence of osteoinductive activity. The microcomputed tomography, Young's modulus, and histology analyses were also employed to demonstrate that PLA-PD-BMP grafted with 1 μg of BMP-2 can induce bone formation. Therefore, the method in this study can be used as a model system to immobilize other growth factors onto various different types of polymer substrates. The highly biomimetic mussel-derived strategy can therefore improve the clinical outcome of polymer-based medical implants in a facile, safe, and effective way.

  13. Bone induction through controlled release of novel BMP-2-related peptide from PTMC11-F127-PTMC11 hydrogels

    International Nuclear Information System (INIS)

    Tang Shuo; Li Jingfeng; Teng Yu; Guo Xiaodong; Zhao Jingjing; Xu Shuyun; Quan Daping

    2012-01-01

    Bone morphogenetic protein 2 (BMP-2) is the most powerful osteogenic factor; its effectiveness in enhancing osteoblastic activation has been confirmed both in vitro and in vivo. We developed a novel peptide (designated P24) derived from the ‘knuckle’ epitope of BMP-2 and found it also had osteogenic bioactivity to some extent. The main objective of this study was to develop a controlled release system based on poly(trimethylene carbonate)–F127–poly(trimethylene carbonate) (PTMC 11 -F127-PTMC 11 ) hydrogels for the P24 peptide, to promote bone formation. By varying the copolymer concentrations, we demonstrated that P24/PTMC 11 -F127-PTMC 11 hydrogels were an efficient system for the sustained release of P24 over 21–35 days. The P24-loaded hydrogels elevated alkaline phosphatase activity and promoted the expression of osteocalcin mRNA in bone marrow stromal cells (BMSCs) in vitro. Radiographic and histological examination showed that P24-loaded hydrogels could induce more effective ectopic bone formation in vivo than P24-free hydrogels. These results indicate that the PTMC 11 -F127-PTMC 11 hydrogel is a suitable carrier for the controlled release of P24, and is a promising injectable biomaterial for the induction of bone regeneration. (paper)

  14. Gelatin Tight-Coated Poly(lactide-co-glycolide Scaffold Incorporating rhBMP-2 for Bone Tissue Engineering

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    Juan Wang

    2015-03-01

    Full Text Available Surface coating is the simplest surface modification. However, bioactive molecules can not spread well on the commonly used polylactone-type skeletons; thus, the surface coatings of biomolecules are typically unstable due to the weak interaction between the polymer and the bioactive molecules. In this study, a special type of poly(lactide-co-glycolide (PLGA-based scaffold with a loosened skeleton was fabricated by phase separation, which allowed gelatin molecules to more readily diffuse throughout the structure. In this application, gelatin modified both the internal substrate and external surface. After cross-linking with glutaraldehyde, the surface layer gelatin was tightly bound to the diffused gelatin, thereby preventing the surface layer gelatin coating from falling off within 14 days. After gelatin modification, PLGA scaffold demonstrated enhanced hydrophilicity and improved mechanical properties (i.e., increased compression strength and elastic modulus in dry and wet states. Furthermore, a sustained release profile of recombinant human bone morphogenetic protein-2 (rhBMP-2 was achieved in the coated scaffold. The coated scaffold also supported the in vitro attachment, proliferation, and osteogenesis of rabbit bone mesenchymal stem cells (BMSCs, indicating the bioactivity of rhBMP-2. These results collectively demonstrate that the cross-linked-gelatin-coated porous PLGA scaffold incorporating bioactive molecules is a promising candidate for bone tissue regeneration.

  15. Cardiogenic induction of pluripotent stem cells streamlined through a conserved SDF-1/VEGF/BMP2 integrated network.

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    Anca Chiriac

    Full Text Available BACKGROUND: Pluripotent stem cells produce tissue-specific lineages through programmed acquisition of sequential gene expression patterns that function as a blueprint for organ formation. As embryonic stem cells respond concomitantly to diverse signaling pathways during differentiation, extraction of a pro-cardiogenic network would offer a roadmap to streamline cardiac progenitor output. METHODS AND RESULTS: To resolve gene ontology priorities within precursor transcriptomes, cardiogenic subpopulations were here generated according to either growth factor guidance or stage-specific biomarker sorting. Innate expression profiles were independently delineated through unbiased systems biology mapping, and cross-referenced to filter transcriptional noise unmasking a conserved progenitor motif (55 up- and 233 down-regulated genes. The streamlined pool of 288 genes organized into a core biological network that prioritized the "Cardiovascular Development" function. Recursive in silico deconvolution of the cardiogenic neighborhood and associated canonical signaling pathways identified a combination of integrated axes, CXCR4/SDF-1, Flk-1/VEGF and BMP2r/BMP2, predicted to synchronize cardiac specification. In vitro targeting of the resolved triad in embryoid bodies accelerated expression of Nkx2.5, Mef2C and cardiac-MHC, enhanced beating activity, and augmented cardiogenic yield. CONCLUSIONS: Transcriptome-wide dissection of a conserved progenitor profile thus revealed functional highways that coordinate cardiogenic maturation from a pluripotent ground state. Validating the bioinformatics algorithm established a strategy to rationally modulate cell fate, and optimize stem cell-derived cardiogenesis.

  16. Abrogation of epithelial BMP2 and BMP4 causes Amelogenesis Imperfecta by reducing MMP20 and KLK4 expression.

    Science.gov (United States)

    Xie, Xiaohua; Liu, Chao; Zhang, Hua; Jani, Priyam H; Lu, Yongbo; Wang, Xiaofang; Zhang, Bin; Qin, Chunlin

    2016-05-05

    Amelogenesis Imperfecta (AI) can be caused by the deficiencies of enamel matrix proteins, molecules responsible for the transportation and secretion of enamel matrix components, and proteases processing enamel matrix proteins. In the present study, we discovered the double deletion of bone morphogenetic protein 2 (Bmp2) and bone morphogenetic protein 4 (Bmp4) in the dental epithelium by K14-cre resulted in hypoplastic enamel and reduced density in X-ray radiography as well as shortened enamel rods under scanning electron microscopy. Such enamel phenotype was consistent with the diagnosis of hypoplastic amelogenesis imperfecta. Histological and molecular analyses revealed that the removal of matrix proteins in the mutant enamel was drastically delayed, which was coincided with the greatly reduced expression of matrix metalloproteinase 20 (MMP20) and kallikrein 4 (KLK4). Although the expression of multiple enamel matrix proteins was down-regulated in the mutant ameloblasts, the cleavage of ameloblastin was drastically impaired. Therefore, we attributed the AI primarily to the reduction of MMP20 and KLK4. Further investigation found that BMP/Smad4 signaling pathway was down-regulated in the K14-cre;Bmp2(f/f);Bmp4(f/f)ameloblasts, suggesting that the reduced MMP20 and KLK4 expression may be due to the attenuated epithelial BMP/Smad4 signaling.

  17. * Calvarial Bone Regeneration Is Enhanced by Sequential Delivery of FGF-2 and BMP-2 from Layer-by-Layer Coatings with a Biomimetic Calcium Phosphate Barrier Layer.

    Science.gov (United States)

    Gronowicz, Gloria; Jacobs, Emily; Peng, Tao; Zhu, Li; Hurley, Marja; Kuhn, Liisa T

    2017-12-01

    A drug delivery coating for synthetic bone grafts has been developed to provide sequential delivery of multiple osteoinductive factors to better mimic aspects of the natural regenerative process. The coating is composed of a biomimetic calcium phosphate (bCaP) layer that is applied to a synthetic bone graft and then covered with a poly-l-Lysine/poly-l-Glutamic acid polyelectrolyte multilayer (PEM) film. Bone morphogenetic protein-2 (BMP-2) was applied before the coating process directly on the synthetic bone graft and then, bCaP-PEM was deposited followed by adsorption of fibroblast growth factor-2 (FGF-2) into the PEM layer. Cells access the FGF-2 immediately, while the bCaP-PEM temporally delays the cell access to BMP-2. In vitro studies with cells derived from mouse calvarial bones demonstrated that Sca-1 and CD-166 positive osteoblast progenitor cells proliferated in response to media dosing with FGF-2. Coated scaffolds with BMP-2 and FGF-2 were implanted in mouse calvarial bone defects and harvested at 1 and 3 weeks. After 1 week in vivo, proliferation of cells, including Sca-1+ progenitors, was observed with low dose FGF-2 and BMP-2 compared to BMP-2 alone, indicating that in vivo delivery of FGF-2 activated a similar population of cells as shown by in vitro testing. At 3 weeks, FGF-2 and BMP-2 delivery increased bone formation more than BMP-2 alone, particularly in the center of the defect, confirming that the proliferation of the Sca-1 positive osteoprogenitors by FGF-2 was associated with increased bone healing. Areas of bone mineralization were positive for double fluorochrome labeling of calcium and alkaline phosphatase staining of osteoblasts, along with increased TRAP+ osteoclasts, demonstrating active bone formation distinct from the bone-like collagen/hydroxyapatite scaffold. In conclusion, the addition of a bCaP layer to PEM delayed access to BMP-2 and allowed the FGF-2 stimulated progenitors to populate the scaffold before differentiating in

  18. Low-dose rhBMP2/7 heterodimer to reconstruct peri-implant bone defects: a micro-CT evaluation.

    Science.gov (United States)

    Wang, Jingxiao; Zheng, Yuanna; Zhao, Juan; Liu, Tie; Gao, Lixia; Gu, Zhiyuan; Wu, Gang

    2012-01-01

    To delineate the dynamic micro-architectures of bone induced by low-dose bone morphogenetic protein (BMP)-2/7 heterodimer in peri-implant bone defects compared to BMP2 and BMP7 homodimer. Peri-implant bone defects (8 mm in diameter, 4 mm in depth) were created surrounding SLA-treated titanium implants (3.1 mm in diameter, 10 mm in length) in minipig's calvaria. We administrated collagen sponges with adsorbed low-dose (30 ng/mm(3) ) BMP2/7 to treat the defects using BMP2, BMP7 or no BMP as controls.2, 3 and 6 weeks after implantation, we adopted micro-computer tomography to evaluate the micro-architectures of new bone using the following parameters: relative bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), connectivity density, and structure mode index (SMI). Bone implant contact (BIC) was also revealed histologically. Consistent with 2 and 3 weeks, after 6 weeks post-operation, BMP2/7 resulted in significantly higher BV/TV (63.033 ± 2.055%) and significantly lower SMI (-4.405 ± 0.500) than BMP2 (BV/TV: 43.133 ± 2.001%; SMI: -0.086 ± 0.041) and BMP7 (BV/TV: 41.467 ± 1.850%; SMI: -0.044 ± 0.016) respectively. Significant differences were also found in Tb.N, Tb.Th and Tb.Sp at all time points. At 2 weeks, BMP2/7 resulted in significantly higher BIC than the controls. Low-dose BMP2/7 heterodimer facilitated more rapid bone regeneration in better quality in peri-implant bone defects than BMP2 and BMP7 homodimers. © 2011 John Wiley & Sons A/S.

  19. Post-transcriptional regulation of vascular endothelial growth factor: Implications for tumor angiogenesis

    Institute of Scientific and Technical Information of China (English)

    Peter S Yoo; Abby L Mulkeen; Charles H Cha

    2006-01-01

    Vascular endothelial growth factor (VEGF) is a potent secreted mitogen critical for physiologic and tumor angiogenesis. Regulation of VEGF occurs at several levels, including transcription, mRNA stabilization,translation, and differential cellular localization of various isoforms. Recent advances in our understanding of posttranscriptional regulation of VEGF include identification of the stabilizing mRNA binding protein, HuR, and the discovery of internal ribosomal entry sites in the 5'UTR of the VEGF mRNA. Monoclonal anti-VEGF antibody was recently approved for use in humans, but suffers from the need for high systemic doses. RNA interference (RNAi)technology is being used in vitro and in animal models with promising results. Here, we review the literature on post-transcriptional regulation of VEGF and describe recent progress in targeting these mechanisms for therapeutic benefit.

  20. Post-transcription cleavage generates the 3' end of F17R transcripts in vaccinia virus

    International Nuclear Information System (INIS)

    D'Costa, Susan M.; Antczak, James B.; Pickup, David J.; Condit, Richard C.

    2004-01-01

    Most vaccinia virus intermediate and late mRNAs possess 3' ends that are extremely heterogeneous in sequence. However, late mRNAs encoding the cowpox A-type inclusion protein (ATI), the second largest subunit of the RNA polymerase, and the late telomeric transcripts possess homogeneous 3' ends. In the case of the ATI mRNA, it has been shown that the homogeneous 3' end is generated by a post-transcriptional endoribonucleolytic cleavage event. We have determined that the F17R gene also produces homogeneous transcripts generated by a post-transcriptional cleavage event. Mapping of in vivo mRNA shows that the major 3' end of the F17R transcript maps 1262 nt downstream of the F17R translational start site. In vitro transcripts spanning the in vivo 3' end are cleaved in an in vitro reaction using extracts from virus infected cells, and the site of cleavage is the same both in vivo and in vitro. Cleavage is not observed using extract from cells infected in the presence of hydroxyurea; therefore, the cleavage factor is either virus-coded or virus-induced during the post-replicative phase of virus replication. The cis-acting sequence responsible for cleavage is orientation specific and the factor responsible for cleavage activity has biochemical properties similar to the factor required for cleavage of ATI transcripts. Partially purified cleavage factor generates cleavage products of expected size when either the ATI or F17R substrates are used in vitro, strongly suggesting that cleavage of both transcripts is mediated by the same factor

  1. Coordinated Evolution of Transcriptional and Post-Transcriptional Regulation for Mitochondrial Functions in Yeast Strains.

    Directory of Open Access Journals (Sweden)

    Xuepeng Sun

    Full Text Available Evolution of gene regulation has been proposed to play an important role in environmental adaptation. Exploring mechanisms underlying coordinated evolutionary changes at various levels of gene regulation could shed new light on how organism adapt in nature. In this study, we focused on regulatory differences between a laboratory Saccharomyces cerevisiae strain BY4742 and a pathogenic S. cerevisiae strain, YJM789. The two strains diverge in many features, including growth rate, morphology, high temperature tolerance, and pathogenicity. Our RNA-Seq and ribosomal footprint profiling data showed that gene expression differences are pervasive, and genes functioning in mitochondria are mostly divergent between the two strains at both transcriptional and translational levels. Combining functional genomics data from other yeast strains, we further demonstrated that significant divergence of expression for genes functioning in the electron transport chain (ETC was likely caused by differential expression of a transcriptional factor, HAP4, and that post-transcriptional regulation mediated by an RNA-binding protein, PUF3, likely led to expression divergence for genes involved in mitochondrial translation. We also explored mito-nuclear interactions via mitochondrial DNA replacement between strains. Although the two mitochondrial genomes harbor substantial sequence divergence, neither growth nor gene expression were affected by mitochondrial DNA replacement in both fermentative and respiratory growth media, indicating compatible mitochondrial and nuclear genomes between these two strains in the tested conditions. Collectively, we used mitochondrial functions as an example to demonstrate for the first time that evolution at both transcriptional and post-transcriptional levels could lead to coordinated regulatory changes underlying strain specific functional variations.

  2. Regulation of host-pathogen interactions via the post-transcriptional Csr/Rsm system.

    Science.gov (United States)

    Kusmierek, Maria; Dersch, Petra

    2018-02-01

    A successful colonization of specific hosts requires a rapid and efficient adaptation of the virulence-relevant gene expression program by bacterial pathogens. An important element in this endeavor is the Csr/Rsm system. This multi-component, post-transcriptional control system forms a central hub within complex regulatory networks and coordinately adjusts virulence properties with metabolic and physiological attributes of the pathogen. A key function is elicited by the RNA-binding protein CsrA/RsmA. CsrA/RsmA interacts with numerous target mRNAs, many of which encode crucial virulence factors, and alters their translation, stability or elongation of transcription. Recent studies highlighted that important colonization factors, toxins, and bacterial secretion systems are under CsrA/RsmA control. CsrA/RsmA deficiency impairs host colonization and attenuates virulence, making this post-transcriptional regulator a suitable drug target. The CsrA/RsmA protein can be inactivated through sequestration by non-coding RNAs, or via binding to specific highly abundant mRNAs and interacting proteins. The wide range of interaction partners and RNA targets, as well as the overarching, interlinked genetic control circuits illustrate the complexity of this regulatory system in the different pathogens. Future work addressing spatio-temporal changes of Csr/Rsm-mediated control during the course of an infection will help us to understand how bacteria reprogram their expression profile to cope with continuous changes experienced in colonized niches. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Phosphorus starvation induces post-transcriptional CHS gene silencing in Petunia corolla.

    Science.gov (United States)

    Hosokawa, Munetaka; Yamauchi, Takayoshi; Takahama, Masayoshi; Goto, Mariko; Mikano, Sachiko; Yamaguchi, Yuki; Tanaka, Yoshiyuki; Ohno, Sho; Koeda, Sota; Doi, Motoaki; Yazawa, Susumu

    2013-05-01

    The corolla of Petunia 'Magic Samba' exhibits unstable anthocyanin expression depending on its phosphorus content. Phosphorus deficiency enhanced post-transcriptional gene silencing of chalcone synthase - A in the corolla. Petunia (Petunia hybrida) 'Magic Samba' has unstable red-white bicolored corollas that respond to nutrient deficiency. We grew this cultivar hydroponically using solutions that lacked one or several nutrients to identify the specific nutrient related to anthocyanin expression in corolla. The white area of the corolla widened under phosphorus (P)-deficient conditions. When the P content of the corolla grown under P-deficient conditions dropped to 40 corollas until the plants died. Other elemental deficiencies had no clear effects on anthocyanin suppression in the corolla. After phosphate was resupplied to the P-deficient plants, anthocyanin was restored in the corollas. The expression of chalcone synthase-A (CHS-A) was suppressed in the white area that widened under P-suppressed conditions, whereas the expression of several other genes related to anthocyanin biosynthesis was enhanced more in the white area than in the red area. Reddish leaves and sepals developed under the P-deficient condition, which is a typical P-deficiency symptom. Two genes related to anthocyanin biosynthesis were enhanced in the reddish organs. Small interfering RNA analysis of CHS-A showed that the suppression resulted from post-transcriptional gene silencing (PTGS). Thus, it was hypothesized that the enhancement of anthocyanin biosynthetic gene expression due to P-deficiency triggered PTGS of CHS-A, which resulted in white corolla development.

  4. Post-transcriptional regulation of MRE11 expression in muscle-invasive bladder tumours.

    Science.gov (United States)

    Martin, Rebecca M; Kerr, Martin; Teo, Mark T W; Jevons, Sarah J; Koritzinsky, Marianne; Wouters, Bradly G; Bhattarai, Selina; Kiltie, Anne E

    2014-02-28

    Predictive assays are needed to help optimise treatment in muscle-invasive bladder cancer, where patients can be treated by either cystectomy or radical radiotherapy. Our finding that low tumour MRE11 expression is predictive of poor response to radiotherapy but not cystectomy was recently independently validated. Here we investigated further the mechanism underlying low MRE11 expression seen in poorly-responding patients. MRE11 RNA and protein levels were measured in 88 bladder tumour patient samples, by real-time PCR and immunohistochemistry respectively, and a panel of eight bladder cancer cell lines was screened for MRE11, RAD50 and NBS1 mRNA and protein expression. There was no correlation between bladder tumour MRE11 protein and RNA scores (Spearman's rho 0.064, p=0.65), suggesting MRE11 is controlled post-transcriptionally, a pattern confirmed in eight bladder cancer cell lines. In contrast, NBS1 and RAD50 mRNA and protein levels were correlated (p=0.01 and p=0.03, respectively), suggesting primary regulation at the level of transcription. MRE11 protein levels were correlated with NBS1 and RAD50 mRNA and protein levels, implicating MRN complex formation as an important determinant of MRE11 expression, driven by RAD50 and NBS1 expression. Our findings of the post-transcriptional nature of the control of MRE11 imply that any predictive assays used in patients need to be performed at the protein level rather than the mRNA level.

  5. Combination of BMP-2-releasing gelatin/β-TCP sponges with autologous bone marrow for bone regeneration of X-ray-irradiated rabbit ulnar defects.

    Science.gov (United States)

    Yamamoto, Masaya; Hokugo, Akishige; Takahashi, Yoshitake; Nakano, Takayoshi; Hiraoka, Masahiro; Tabata, Yasuhiko

    2015-07-01

    The objective of this study is to evaluate the feasibility of gelatin sponges incorporating β-tricalcium phosphate (β-TCP) granules (gelatin/β-TCP sponges) to enhance bone regeneration at a segmental ulnar defect of rabbits with X-ray irradiation. After X-ray irradiation of the ulnar bone, segmental critical-sized defects of 20-mm length were created, and bone morphogenetic protein-2 (BMP-2)-releasing gelatin/β-TCP sponges with or without autologous bone marrow were applied to the defects to evaluate bone regeneration. Both gelatin/β-TCP sponges containing autologous bone marrow and BMP-2-releasing sponges enhanced bone regeneration at the ulna defect to a significantly greater extent than the empty sponges (control). However, in the X-ray-irradiated bone, the bone regeneration either by autologous bone marrow or BMP-2 was inhibited. When combined with autologous bone marrow, the BMP-2 exhibited significantly high osteoinductivity, irrespective of the X-ray irradiation. The bone mineral content at the ulna defect was similar to that of the intact bone. It is concluded that the combination of bone marrow with the BMP-2-releasing gelatin/β-TCP sponge is a promising technique to induce bone regeneration at segmental bone defects after X-ray irradiation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Sequential VEGF and BMP-2 releasing PLA-PEG-PLA scaffolds for bone tissue engineering: I. Design and in vitro tests.

    Science.gov (United States)

    Eğri, Sinan; Eczacıoğlu, Numan

    2017-03-01

    Biodegradable PLA-PEG-PLA block copolymers were synthesized with desired backbone structures and molecular weights using PEG20000. Rectangular scaffolds were prepared by freeze drying with or without using NaCl particles. Bone morphogenetic protein (BMP)-2 was loaded to the matrix after the scaffold formation for sustained release while vascular endothelial growth factor (VEGF) was loaded within the pores with gelatin solution. VEGF release was quite fast and almost 60% of it was released in 2 d. However, sequential - sustained released was observed for BMP-2 in the following few months. Corporation of VEGF/BMP-2 couple into the scaffolds increased the cell adhesion and proliferation. Neither significant cytotoxicity nor apoptosis/necrosis were observed.

  7. Curcumin induces osteoblast differentiation through mild-endoplasmic reticulum stress-mediated such as BMP2 on osteoblast cells.

    Science.gov (United States)

    Son, Hyo-Eun; Kim, Eun-Jung; Jang, Won-Gu

    2018-01-15

    Curcumin (diferuloylmethane or [1E,6E]-1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6heptadiene-3,5-dione) is a phenolic natural product derived from the rhizomes of the turmeric plant, Curcuma longa. It is reported to have various biological actions such as anti-oxidative, anti-inflammatory, and anti-cancer effects. However, the molecular mechanism of osteoblast differentiation by curcumin has not yet been reported. The cytotoxicity of curcumin was identified using the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Expression of osteogenic markers and endoplasmic reticulum (ER) stress markers in C3H1-T1/2 cells were measured using reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blotting. Alkaline phosphatase (ALP) staining was performed to assess ALP activity in C3H10T1/2 cells. Transcriptional activity was detected using a luciferase reporter assay. Curcumin increased the expression of genes such as distal-less homeobox 5 (Dlx5), runt-related transcription factor 2 (Runx2), ALP, and osteocalcin (OC), which subsequently induced osteoblast differentiation in C3H10T1/2 cells. In addition, ALP activity and mineralization was found to be increased by curcumin treatment. Curcumin also induced mild ER stress similar to bone morphogenetic protein 2 (BMP2) function in osteoblast cells. Next, we confirmed that curcumin increased mild ER stress and osteoblast differentiation similar to BMP2 in C3H10T1/2 mesenchymal stem cells. Transient transfection studies also showed that curcumin increased ATF6-Luc activity, while decreasing the activities of CREBH-Luc and SMILE-Luc. In addition, similar to BMP2, curcumin induced the phosphorylation of Smad 1/5/9. Overall, these results demonstrate that curcumin-induced mild ER stress increases osteoblast differentiation via ATF6 expression in C3H10T1/2 cells. Copyright © 2017. Published by Elsevier Inc.

  8. Three-Dimensional Cone Beam Computed Tomography Volumetric Outcomes of rhBMP-2/Demineralized Bone Matrix versus Iliac Crest Bone Graft for Alveolar Cleft Reconstruction.

    Science.gov (United States)

    Liang, Fan; Yen, Stephen L-K; Imahiyerobo, Thomas; Sanborn, Luke; Yen, Leia; Yen, Daniel; Nazarian, Sheila; Jedrzejewski, Breanna; Urata, Mark; Hammoudeh, Jeffrey

    2017-10-01

    Recent studies indicate that recombinant human bone morphogenetic protein-2 (rhBMP-2) in a demineralized bone matrix scaffold is a comparable alternative to iliac bone autograft in the setting of secondary alveolar cleft repair. Postreconstruction occlusal radiographs demonstrate improved bone stock when rhBMP-2/demineralized bone matrix (DBM) scaffold is used but lack the capacity to evaluate bone growth in three dimensions. This study uses cone beam computed tomography to provide the first clinical evaluation of volumetric and density comparisons between these two treatment modalities. A prospective study was conducted with 31 patients and 36 repairs of the alveolar cleft over a 2-year period. Twenty-one repairs used rhBMP-2/DBM scaffold and 14 repairs used iliac bone grafting. Postoperatively, occlusal radiographs were obtained at 3 months to evaluate bone fill; cone beam computed tomographic images were obtained at 6 to 9 months to compare volumetric and density data. At 3 months, postoperative occlusal radiographs demonstrated that 67 percent of patients receiving rhBMP-2/DBM scaffold had complete bone fill of the alveolus, versus 56 percent of patients in the autologous group. In contrast, cone beam computed tomographic data showed 31.6 percent (95 percent CI, 24.2 to 38.5 percent) fill in the rhBMP-2 group compared with 32.5 percent (95 percent CI, 22.1 to 42.9 percent) in the autologous population. Density analysis demonstrated identical average values between the groups (1.38 g/cc). These data demonstrate comparable bone regrowth and density values following secondary alveolar cleft repair using rhBMP-2/DBM scaffold versus autologous iliac bone graft. Cone beam computed tomography provides a more nuanced understanding of true bone regeneration within the alveolar cleft that may contribute to the information provided by occlusal radiographs alone. Therapeutic, II.

  9. Overlapping and differential localization of Bmp-2, Bmp-4, Msx-2 and apoptosis in the endocardial cushion and adjacent tissues of the developing mouse heart.

    Science.gov (United States)

    Abdelwahid, E; Rice, D; Pelliniemi, L J; Jokinen, E

    2001-07-01

    The bone morphogenetic proteins BMP-2 and BMP-4 and the homeobox gene MSX-2 are required for normal development of many embryonic tissues. To elucidate their possible roles during the remodeling of the tubular heart into a fully septated four-chambered heart, we have localized the mRNA of Bmp-2, Bmp-4, Msx-2 and apoptotic cells in the developing mouse heart from embryonic day (E)11 to E17. mRNA was localized by in situ hybridization, and apoptotic cells by TUNEL (TDT-mediated dUTP-biotin nick end-labeling) as well as by transmission electron microscopy. By analyzing adjacent serial sections, we demonstrated that the expression of Msx-2 and Bmp-2 strikingly overlapped in the atrioventricular canal myocardium, in the atrioventricular junctional myocardium, and in the maturing myocardium of the atrioventricular valves. Bmp-4 was expressed in the outflow tract myocardium and in the endocardial cushion of the outflow tract ridges from E12 to E14. Msx-2 appeared in the mesenchyme of the atrioventricular endocardial cushion from E11 to E14, while Bmp-2 and Bmp-4 were detected between E11 and E14. Apoptotic cells were also detected in the mesenchyme of the endocardial cushion between E12 and E14. Our results suggest that BMP-2 and MSX-2 are tightly linked to the formation of the atrioventricular junction and valves and that BMP-4 is involved in the development of the outflow tract myocardium and of the endocardial cushion. In addition, BMP-2, BMP-4 and MSX-2 and apoptosis seem to be associated with differentiation of the endocardial cushion.

  10. Early changes in retinal structure and BMP2 expression in the retina and crystalline lens of streptozotocin-induced diabetic pigs.

    Science.gov (United States)

    Jeong, Jae Seung; Lee, Woon-Kyu; Moon, Yeon Sung; Kim, Na Rae

    2017-09-01

    This study aims to evaluate early changes in retinal structure and BMP2 expression in the retina and crystalline lens by comparing streptozotocin-induced diabetic pigs and normal control group pigs. Five eye samples from five diabetic Micro-pigs (Medikinetics, Pyeongtaek, Korea) and five eye samples from five control pigs bred in a specific pathogen-free area were used. Diabetes was developed through intravenous injection of nicotinamide and streptozotocin, and the average fasting glucose level was maintained at 250 mg/dL or higher for 16 weeks. To evaluate BMP2 expression in the retina and crystalline lens, Western blotting was performed. In Hematoxylin and Eosin staining, most diabetic pigs showed structural abnormalities in the inner plexiform layer. The number of nuclei in the ganglion cell layer within the range of 10 4 µm 2 was 3.78±0.60 for diabetic pigs and 5.57±1.07 for control group pigs, showing a statistically significant difference. In immunohistochemical staining, diabetic retinas showed an overall increase in BMP2 expression. In Western blotting, the average BMP2/actin level of diabetic retinas was 1.19±0.05, showing a significant increase compared to the 1.06±0.03 of the control group retinas ( P =0.016). The BMP2/actin level of diabetic crystalline lenses was similar to the control group crystalline lenses ( P =0.730). Compared to control group pigs, the number of nuclei in the inner nuclear layer of retinas from streptozotocin-induced diabetic pigs decreased, while an increase in BMP2 expression was observed in the retina of diabetic pigs.

  11. Effects of BMP-2 and dexamethasone on osteogenic differentiation of rat dental follicle progenitor cells seeded on three-dimensional beta-TCP

    Energy Technology Data Exchange (ETDEWEB)

    Xu Lulu; Jin Zuolin; Duan Yinzhong [Department of Orthodontics, Stomatological College, Fourth Military Medical University, Xi' an 710032 (China); Liu Hongchen; Wang Dongsheng; E Lingling [Department of Stomatology, China PLA General Hospital, Beijing 100853 (China); Xu Lin, E-mail: jinzuolin88@yahoo.com.c, E-mail: duanyinzhong@yahoo.com.c [Department of Stomatology, the First Hospital of PLA, Lanzhou 730000 (China)

    2009-12-15

    The aim of this study was to investigate the effects of BMP-2 and dexamethasone (Dex) on osteogenic differentiation of rat dental follicle progenitor cells (RDFCs) seeded on three-dimensional beta-TCP. The alkaline phosphatase (ALP), the calcium and phosphonium, the osteocalcin in media of the third passage RDFCs on biomaterial beta-TCP after 1-3, 3-7, 7-14 days of culture were examined respectively. The growth of cells on the scaffolds was observed by scanning electron microscope (SEM) after 3, 7 days of culture and by implanting in the backs of severe combined immunodeficient (SCID) mice for bone regeneration. The third passage RDFCs could be seen adhered, extended and proliferated on the beta-TCP by scanning electron microscopy. The ALP activity, the calcium and phosphoniums and the osteocalcin content of dexamethasone (10{sup -8} M) or/and BMP-2 (100 ng ml{sup -1}) were significantly higher than their existence in the control group. They were the significantly highest among four groups after joint application of BMP-2 and dexamethasone. After 8 weeks of implantation, the percentage of the new bones formed area in the RDFCs+beta-TCP+BMP-2+Dex group was significantly higher than that in the RDFCs+beta-TCP+BMP-2 group. In contrast, beta-TCP, RDFCs+beta-TCP+Dex and control constructs lacked new bone formation by histological staining and histomorphometric analysis. The BMP-2+Dex could significantly promote osteogenic differentiation of RDFCs on beta-TCP. beta-TCP supported fast cellular adhesion, proliferation and differentiation of RDFCs. The feasibility of its application in periodontal tissue engineering was also proved.

  12. Effects of BMP-2 and dexamethasone on osteogenic differentiation of rat dental follicle progenitor cells seeded on three-dimensional β-TCP

    International Nuclear Information System (INIS)

    Xu Lulu; Jin Zuolin; Duan Yinzhong; Liu Hongchen; Wang Dongsheng; E Lingling; Xu Lin

    2009-01-01

    The aim of this study was to investigate the effects of BMP-2 and dexamethasone (Dex) on osteogenic differentiation of rat dental follicle progenitor cells (RDFCs) seeded on three-dimensional β-TCP. The alkaline phosphatase (ALP), the calcium and phosphonium, the osteocalcin in media of the third passage RDFCs on biomaterial β-TCP after 1-3, 3-7, 7-14 days of culture were examined respectively. The growth of cells on the scaffolds was observed by scanning electron microscope (SEM) after 3, 7 days of culture and by implanting in the backs of severe combined immunodeficient (SCID) mice for bone regeneration. The third passage RDFCs could be seen adhered, extended and proliferated on the β-TCP by scanning electron microscopy. The ALP activity, the calcium and phosphoniums and the osteocalcin content of dexamethasone (10 -8 M) or/and BMP-2 (100 ng ml -1 ) were significantly higher than their existence in the control group. They were the significantly highest among four groups after joint application of BMP-2 and dexamethasone. After 8 weeks of implantation, the percentage of the new bones formed area in the RDFCs+β-TCP+BMP-2+Dex group was significantly higher than that in the RDFCs+β-TCP+BMP-2 group. In contrast, β-TCP, RDFCs+β-TCP+Dex and control constructs lacked new bone formation by histological staining and histomorphometric analysis. The BMP-2+Dex could significantly promote osteogenic differentiation of RDFCs on β-TCP. β-TCP supported fast cellular adhesion, proliferation and differentiation of RDFCs. The feasibility of its application in periodontal tissue engineering was also proved.

  13. Elucidating MicroRNA Regulatory Networks Using Transcriptional, Post-transcriptional, and Histone Modification Measurements

    Directory of Open Access Journals (Sweden)

    Sara J.C. Gosline

    2016-01-01

    Full Text Available MicroRNAs (miRNAs regulate diverse biological processes by repressing mRNAs, but their modest effects on direct targets, together with their participation in larger regulatory networks, make it challenging to delineate miRNA-mediated effects. Here, we describe an approach to characterizing miRNA-regulatory networks by systematically profiling transcriptional, post-transcriptional and epigenetic activity in a pair of isogenic murine fibroblast cell lines with and without Dicer expression. By RNA sequencing (RNA-seq and CLIP (crosslinking followed by immunoprecipitation sequencing (CLIP-seq, we found that most of the changes induced by global miRNA loss occur at the level of transcription. We then introduced a network modeling approach that integrated these data with epigenetic data to identify specific miRNA-regulated transcription factors that explain the impact of miRNA perturbation on gene expression. In total, we demonstrate that combining multiple genome-wide datasets spanning diverse regulatory modes enables accurate delineation of the downstream miRNA-regulated transcriptional network and establishes a model for studying similar networks in other systems.

  14. Harnessing CRISPR/Cas systems for programmable transcriptional and post-transcriptional regulation

    KAUST Repository

    Mahas, Ahmed

    2017-11-29

    Genome editing has enabled broad advances and novel approaches in studies of gene function and structure; now, emerging methods aim to precisely engineer post-transcriptional processes. Developing precise, efficient molecular tools to alter the transcriptome holds great promise for biotechnology and synthetic biology applications. Different approaches have been employed for targeted degradation of RNA species in eukaryotes, but they lack programmability and versatility, thereby limiting their utility for diverse applications. The CRISPR/Cas9 system has been harnessed for genome editing in many eukaryotic species and, using a catalytically inactive Cas9 variant, the CRISPR/dCas9 system has been repurposed for transcriptional regulation. Recent studies have used other CRISPR/Cas systems for targeted RNA degradation and RNA-based manipulations. For example, Cas13a, a Type VI-A endonuclease, has been identified as an RNA-guided RNA ribonuclease and used for manipulation of RNA. Here, we discuss different modalities for targeted RNA interference with an emphasis on the potential applications of CRISPR/Cas systems as programmable transcriptional regulators for broad uses, including functional biology, biotechnology, and synthetic biology applications.

  15. Post-transcriptional control of the mammalian circadian clock: implications for health and disease.

    Science.gov (United States)

    Preußner, Marco; Heyd, Florian

    2016-06-01

    Many aspects of human physiology and behavior display rhythmicity with a period of approximately 24 h. Rhythmic changes are controlled by an endogenous time keeper, the circadian clock, and include sleep-wake cycles, physical and mental performance capability, blood pressure, and body temperature. Consequently, many diseases, such as metabolic, sleep, autoimmune and mental disorders and cancer, are connected to the circadian rhythm. The development of therapies that take circadian biology into account is thus a promising strategy to improve treatments of diverse disorders, ranging from allergic syndromes to cancer. Circadian alteration of body functions and behavior are, at the molecular level, controlled and mediated by widespread changes in gene expression that happen in anticipation of predictably changing requirements during the day. At the core of the molecular clockwork is a well-studied transcription-translation negative feedback loop. However, evidence is emerging that additional post-transcriptional, RNA-based mechanisms are required to maintain proper clock function. Here, we will discuss recent work implicating regulated mRNA stability, translation and alternative splicing in the control of the mammalian circadian clock, and its role in health and disease.

  16. Post-transcriptional regulation of macrophage ABCA1, an early response gene to IFN-γ

    International Nuclear Information System (INIS)

    Alfaro Leon, Martha Leticia; Evans, Glenn F.; Farmen, Mark W.; Zuckerman, Steven H.

    2005-01-01

    Interferon-γ (IFN-γ) down-regulates receptors associated with reverse cholesterol transport including ABCA1. In the present study, the kinetics and mechanism of ABCA1 down-regulation were determined in mouse peritoneal macrophages. IFN-γ decreased ABCA1 mRNA 1 h following IFN-γ addition and was maximally reduced by 3 h. Down-regulation was protein synthesis dependent and involved post-transcriptional processes. ABCA1 message had a T 1/2 of 115 min in actinomycin treated cells that was reduced to a T 1/2 of 37 min by IFN-γ. The decrease in message stability was also associated with a rapid loss of ABCA1 protein, significant 3 h following IFN-γ addition. The kinetics of ABCA1 message and protein decrease was consistent with the early IFN-γ-induced changes in Stat1 phosphorylation and nuclear translocation observed in these cells. Therefore, ABCA1 can be considered as an early response gene to macrophage activation by IFN-γ with down-regulation occurring by message destabilization

  17. Harnessing CRISPR/Cas systems for programmable transcriptional and post-transcriptional regulation

    KAUST Repository

    Mahas, Ahmed; Neal Stewart, C.; Mahfouz, Magdy M.

    2017-01-01

    Genome editing has enabled broad advances and novel approaches in studies of gene function and structure; now, emerging methods aim to precisely engineer post-transcriptional processes. Developing precise, efficient molecular tools to alter the transcriptome holds great promise for biotechnology and synthetic biology applications. Different approaches have been employed for targeted degradation of RNA species in eukaryotes, but they lack programmability and versatility, thereby limiting their utility for diverse applications. The CRISPR/Cas9 system has been harnessed for genome editing in many eukaryotic species and, using a catalytically inactive Cas9 variant, the CRISPR/dCas9 system has been repurposed for transcriptional regulation. Recent studies have used other CRISPR/Cas systems for targeted RNA degradation and RNA-based manipulations. For example, Cas13a, a Type VI-A endonuclease, has been identified as an RNA-guided RNA ribonuclease and used for manipulation of RNA. Here, we discuss different modalities for targeted RNA interference with an emphasis on the potential applications of CRISPR/Cas systems as programmable transcriptional regulators for broad uses, including functional biology, biotechnology, and synthetic biology applications.

  18. Transcriptional and post-transcriptional regulation of nucleotide excision repair genes in human cells

    Energy Technology Data Exchange (ETDEWEB)

    Lefkofsky, Hailey B. [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Veloso, Artur [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Bioinformatics Program, Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI (United States); Ljungman, Mats, E-mail: ljungman@umich.edu [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI (United States)

    2015-06-15

    Nucleotide excision repair (NER) removes DNA helix-distorting lesions induced by UV light and various chemotherapeutic agents such as cisplatin. These lesions efficiently block the elongation of transcription and need to be rapidly removed by transcription-coupled NER (TC-NER) to avoid the induction of apoptosis. Twenty-nine genes have been classified to code for proteins participating in nucleotide excision repair (NER) in human cells. Here we explored the transcriptional and post-transcriptional regulation of these NER genes across 13 human cell lines using Bru-seq and BruChase-seq, respectively. Many NER genes are relatively large in size and therefore will be easily inactivated by UV-induced transcription-blocking lesions. Furthermore, many of these genes produce transcripts that are rather unstable. Thus, these genes are expected to rapidly lose expression leading to a diminished function of NER. One such gene is ERCC6 that codes for the CSB protein critical for TC-NER. Due to its large gene size and high RNA turnover rate, the ERCC6 gene may act as dosimeter of DNA damage so that at high levels of damage, ERCC6 RNA levels would be diminished leading to the loss of CSB expression, inhibition of TC-NER and the promotion of cell death.

  19. Bone regeneration of critical calvarial defect in goat model by PLGA/TCP/rhBMP-2 scaffolds prepared by low-temperature rapid-prototyping technology.

    Science.gov (United States)

    Yu, D; Li, Q; Mu, X; Chang, T; Xiong, Z

    2008-10-01

    Active artificial bone composed of poly lactide-co-glycolide (PLGA)/ tricalcium phosphate (TCP) was prefabricated using low-temperature rapid-prototyping technology so that the process of osteogenesis could be observed in it. PLGA and TCP were the primary materials, they were molded at low temperature, then recombinant human bone morphogenetic protein-2 (rhBMP-2) was added to form an active artificial bone. Goats with standard cranial defects were randomly divided into experimental (implants with rhBMP-2 added) and control (implants without rhBMP-2) groups, and osteogenesis was observed and evaluated by imaging and biomechanical and histological examinations. The PLGA-TCP artificial bone scaffold (90% porosity) had large and small pores of approximately 360microm and 3-5microm diameter. Preliminary and complete repair of the cranial defect in the goats occurred 12 and 24 weeks after surgery, respectively. The three-point bending strength of the repaired defects attained that of the normal cranium. In conclusion, low-temperature rapid-prototyping technology can preserve the biological activity of this scaffold material. The scaffold has a good three-dimensional structure and it becomes an active artificial bone after loading with rhBMP-2 with a modest degradation rate and excellent osteogenesis in the goat.

  20. Vitamin C-linker-conjugated tripeptide AHK stimulates BMP-2-induced osteogenic differentiation of mouse myoblast C2C12 cells.

    Science.gov (United States)

    Jung, Jung-Il; Park, Kyeong-Yong; Lee, Yura; Park, Mira; Kim, Jiyeon

    2018-03-15

    Vitamin C-linker-conjugated Ala-His-Lys tripeptide (Vit C-AHK) is a derivative of Vitamin C-conjugated tripeptides, which were originally developed as a component of a product for collagen synthesis enhancement or human dermal fibroblast growth. Here, we investigated the effect of Vit C-AHK on bone morphogenetic protein (BMP)-2-induced osteoblast differentiation in a cell culture model. Vit C-AHK enhanced proliferation of C2C12 cells and induction of BMP-2-induced alkaline phosphatase, a typical marker of osteoblast differentiation. Vit C-AHK also stimulated the phosphorylation and translocation of Smad1/5/8 to the nucleus and phosphorylation of mitogen-activated protein kinases (MAPKs) including ERK1/2 and p38. In addition, Vit C-AHK enhanced the BMP-2-induced mRNA expression of osteoblast differentiation-related genes such as ALP, BMP-2, Osteocalcin, and Runx2. Our results suggest that Vit C-AHK exerts an enhancing effect on osteoblast proliferation and differentiation through activation of Smad1/5/8 and MAPK ERK1/2 and p38 signaling and without significant cytotoxicity. These results provide important data for the development of peptide-based bone-regenerative agents and treatment of bone-related disorders. Copyright © 2018 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

  1. Dual Delivery of BMP-2 and bFGF from a New Nano-Composite Scaffold, Loaded with Vascular Stents for Large-Size Mandibular Defect Regeneration

    Directory of Open Access Journals (Sweden)

    Hang Zhao

    2013-06-01

    Full Text Available The aim of this study was to investigate the feasibility and advantages of the dual delivery of bone morphogenetic protein-2 (BMP-2 and basic fibroblast growth factor (bFGF from nano-composite scaffolds (PLGA/PCL/nHA loaded with vascular stents (PLCL/Col/nHA for large bone defect regeneration in rabbit mandibles. Thirty-six large bone defects were repaired in rabbits using engineering bone composed of allogeneic bone marrow mesenchymal stem cells (BMSCs, bFGF, BMP-2 and scaffolds composed of PLGA/PCL/nHA loaded with PLCL/Col/nHA. The experiments were divided into six groups: BMSCs/bFGF/BMP-2/scaffold, BMSCs/BMP-2/scaffold, BMSCs/bFGF/scaffold, BMSCs/scaffold, scaffold alone and no treatment. Sodium alginate hydrogel was used as the carrier for BMP-2 and bFGF and its features, including gelling, degradation and controlled release properties, was detected by the determination of gelation and degradation time coupled with a controlled release study of bovine serum albumin (BSA. AlamarBlue assay and alkaline phosphatase (ALP activity were used to evaluate the proliferation and osteogenic differentiation of BMSCs in different groups. X-ray and histological examinations of the samples were performed after 4 and 12 weeks post-implantation to clarify new bone formation in the mandible defects. The results verified that the use of sodium alginate hydrogel as a controlled release carrier has good sustained release ability, and the combined application of bFGF and BMP-2 could significantly promote the proliferation and osteogenic differentiation of BMSCs (p < 0.05 or p < 0.01. In addition, X-ray and histological examinations of the samples exhibited that the dual release group had significantly higher bone formation than the other groups. The above results indicate that the delivery of both growth factors could enhance new bone formation and vascularization compared with delivery of BMP-2 or bFGF alone, and may supply a promising way of repairing large

  2. Efficacy of rhBMP-2 Loaded PCL/β-TCP/bdECM Scaffold Fabricated by 3D Printing Technology on Bone Regeneration

    Directory of Open Access Journals (Sweden)

    Eun-Bin Bae

    2018-01-01

    Full Text Available This study was undertaken to evaluate the effect of 3D printed polycaprolactone (PCL/β-tricalcium phosphate (β-TCP scaffold containing bone demineralized and decellularized extracellular matrix (bdECM and human recombinant bone morphogenetic protein-2 (rhBMP-2 on bone regeneration. Scaffolds were divided into PCL/β-TCP, PCL/β-TCP/bdECM, and PCL/β-TCP/bdECM/BMP groups. In vitro release kinetics of rhBMP-2 were determined with respect to cell proliferation and osteogenic differentiation. These three reconstructive materials were implanted into 8 mm diameter calvarial bone defect in male Sprague-Dawley rats. Animals were sacrificed four weeks after implantation for micro-CT, histologic, and histomorphometric analyses. The findings obtained were used to calculate new bone volumes (mm3 and new bone areas (%. Excellent cell bioactivity was observed in the PCL/β-TCP/bdECM and PCL/β-TCP/bdECM/BMP groups, and new bone volume and area were significantly higher in the PCL/β-TCP/bdECM/BMP group than in the other groups (p<.05. Within the limitations of this study, bdECM printed PCL/β-TCP scaffolds can reproduce microenvironment for cells and promote adhering and proliferating the cells onto scaffolds. Furthermore, in the rat calvarial defect model, the scaffold which printed rhBMP-2 loaded bdECM stably carries rhBMP-2 and enhances bone regeneration confirming the possibility of bdECM as rhBMP-2 carrier.

  3. Cryogenic 3D printing for producing hierarchical porous and rhBMP-2-loaded Ca-P/PLLA nanocomposite scaffolds for bone tissue engineering.

    Science.gov (United States)

    Wang, Chong; Zhao, Qilong; Wang, Min

    2017-06-07

    The performance of bone tissue engineering scaffolds can be assessed through cell responses to scaffolds, including cell attachment, infiltration, morphogenesis, proliferation, differentiation, etc, which are determined or heavily influenced by the composition, structure, mechanical properties, and biological properties (e.g. osteoconductivity and osteoinductivity) of scaffolds. Although some promising 3D printing techniques such as fused deposition modeling and selective laser sintering could be employed to produce biodegradable bone tissue engineering scaffolds with customized shapes and tailored interconnected pores, effective methods for fabricating scaffolds with well-designed hierarchical porous structure (both interconnected macropores and surface micropores) and tunable osteoconductivity/osteoinductivity still need to be developed. In this investigation, a novel cryogenic 3D printing technique was investigated and developed for producing hierarchical porous and recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded calcium phosphate (Ca-P) nanoparticle/poly(L-lactic acid) nanocomposite scaffolds, in which the Ca-P nanoparticle-incorporated scaffold layer and rhBMP-2-encapsulated scaffold layer were deposited alternatingly using different types of emulsions as printing inks. The mechanical properties of the as-printed scaffolds were comparable to those of human cancellous bone. Sustained releases of Ca 2+ ions and rhBMP-2 were achieved and the biological activity of rhBMP-2 was well-preserved. Scaffolds with a desirable hierarchical porous structure and dual delivery of Ca 2+ ions and rhBMP-2 exhibited superior performance in directing the behaviors of human bone marrow-derived mesenchymal stem cells and caused improved cell viability, attachment, proliferation, and osteogenic differentiation, which has suggested their great potential for bone tissue engineering.

  4. Effect of Emdogain enamel matrix derivative and BMP-2 on the gene expression and mineralized nodule formation of alveolar bone proper-derived stem/progenitor cells.

    Science.gov (United States)

    Fawzy El-Sayed, Karim M; Dörfer, Christof; Ungefroren, Hendrick; Kassem, Neemat; Wiltfang, Jörg; Paris, Sebastian

    2014-07-01

    The objective of this study was to evaluate the effect of Emdogain (Enamel Matrix Derivative, EMD) and Bone Morphogenetic Protein-2 (BMP-2), either solely or in combination, on the gene expression and mineralized nodule formation of alveolar bone proper-derived stem/progenitor cells. Stem/progenitor cells were isolated from human alveolar bone proper, magnetically sorted using STRO-1 antibodies, characterized flowcytometrically for their surface markers' expression, and examined for colony formation and multilineage differentiation potential. Subsequently, cells were treated over three weeks with 100 μg/ml Emdogain (EMD-Group), or 100 ng/ml BMP-2 (BMP-Group), or a combination of 100 ng/ml BMP-2 and 100 μg/ml Emdogain (BMP/EMD-Group). Unstimulated stem/progenitor cells (MACS(+)-Group) and osteoblasts (OB-Group) served as controls. Osteogenic gene expression was analyzed using RTq-PCR after 1, 2 and 3 weeks (N = 3/group). Mineralized nodule formation was evaluated by Alizarin-Red staining. BMP and EMD up-regulated the osteogenic gene expression. The BMP Group showed significantly higher expression of Collagen-I, III, and V, Alkaline phosphatase and Osteonectin compared to MACS(+)- and OB-Group (p < 0.05; Two-way ANOVA/Bonferroni) with no mineralized nodule formation. Under in-vitro conditions, Emdogain and BMP-2 up-regulate the osteogenic gene expression of stem/progenitor cells. The combination of BMP-2 and Emdogain showed no additive effect and would not be recommended for a combined clinical stimulation. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  5. Smad4 mediated BMP2 signal is essential for the regulation of GATA4 and Nkx2.5 by affecting the histone H3 acetylation in H9c2 cells

    International Nuclear Information System (INIS)

    Si, Lina; Shi, Jin; Gao, Wenqun; Zheng, Min; Liu, Lingjuan; Zhu, Jing; Tian, Jie

    2014-01-01

    Highlights: • BMP2 can upregulated cardiac related gene GATA4, Nkx2.5, MEF2c and Tbx5. • Inhibition of Smad4 decreased BMP2-induced hyperacetylation of histone H3. • Inhibition of Smad4 diminished BMP2-induced overexpression of GATA4 and Nkx2.5. • Inhibition of Smad4 decreased hyperacetylated H3 in the promoter of GATA4 and Nkx2.5. • Smad4 is essential for BMP2 induced hyperacetylated histone H3. - Abstract: BMP2 signaling pathway plays critical roles during heart development, Smad4 encodes the only common Smad protein in mammals, which is a pivotal nuclear mediator. Our previous studies showed that BMP2 enhanced the expression of cardiac transcription factors in part by increasing histone H3 acetylation. In the present study, we tested the hypothesis that Smad4 mediated BMP2 signaling pathway is essential for the expression of cardiac core transcription factors by affecting the histone H3 acetylation. We successfully constructed a lentivirus-mediated short hairpin RNA interference vector targeting Smad4 (Lv-Smad4) in rat H9c2 embryonic cardiac myocytes (H9c2 cells) and demonstrated that it suppressed the expression of the Smad4 gene. Cultured H9c2 cells were transfected with recombinant adenoviruses expressing human BMP2 (AdBMP2) with or without Lv-Smad4. Quantitative real-time RT-PCR analysis showed that knocking down of Smad4 substantially inhibited both AdBMP2-induced and basal expression levels of cardiac transcription factors GATA4 and Nkx2.5, but not MEF2c and Tbx5. Similarly, chromatin immunoprecipitation (ChIP) analysis showed that knocking down of Smad4 inhibited both AdBMP2-induced and basal histone H3 acetylation levels in the promoter regions of GATA4 and Nkx2.5, but not of Tbx5 and MEF2c. In addition, Lv-Smad4 selectively suppressed AdBMP2-induced expression of HAT p300, but not of HAT GCN5 in H9c2 cells. The data indicated that inhibition of Smad4 diminished both AdBMP2 induced and basal histone acetylation levels in the promoter regions of

  6. Smad4 mediated BMP2 signal is essential for the regulation of GATA4 and Nkx2.5 by affecting the histone H3 acetylation in H9c2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Si, Lina; Shi, Jin; Gao, Wenqun [Heart Centre, Children’s Hospital of Chongqing Medical University, 136 Zhongshan 2nd Road, Yu Zhong District, Chongqing 400014 (China); Ministry of Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in Chongqing, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, 136 Zhongshan 2nd Road, Yu Zhong District, Chongqing 400014 (China); Zheng, Min [Heart Centre, Children’s Hospital of Chongqing Medical University, 136 Zhongshan 2nd Road, Yu Zhong District, Chongqing 400014 (China); Liu, Lingjuan; Zhu, Jing [Ministry of Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in Chongqing, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, 136 Zhongshan 2nd Road, Yu Zhong District, Chongqing 400014 (China); Tian, Jie, E-mail: jietian@cqmu.edu.cn [Heart Centre, Children’s Hospital of Chongqing Medical University, 136 Zhongshan 2nd Road, Yu Zhong District, Chongqing 400014 (China)

    2014-07-18

    Highlights: • BMP2 can upregulated cardiac related gene GATA4, Nkx2.5, MEF2c and Tbx5. • Inhibition of Smad4 decreased BMP2-induced hyperacetylation of histone H3. • Inhibition of Smad4 diminished BMP2-induced overexpression of GATA4 and Nkx2.5. • Inhibition of Smad4 decreased hyperacetylated H3 in the promoter of GATA4 and Nkx2.5. • Smad4 is essential for BMP2 induced hyperacetylated histone H3. - Abstract: BMP2 signaling pathway plays critical roles during heart development, Smad4 encodes the only common Smad protein in mammals, which is a pivotal nuclear mediator. Our previous studies showed that BMP2 enhanced the expression of cardiac transcription factors in part by increasing histone H3 acetylation. In the present study, we tested the hypothesis that Smad4 mediated BMP2 signaling pathway is essential for the expression of cardiac core transcription factors by affecting the histone H3 acetylation. We successfully constructed a lentivirus-mediated short hairpin RNA interference vector targeting Smad4 (Lv-Smad4) in rat H9c2 embryonic cardiac myocytes (H9c2 cells) and demonstrated that it suppressed the expression of the Smad4 gene. Cultured H9c2 cells were transfected with recombinant adenoviruses expressing human BMP2 (AdBMP2) with or without Lv-Smad4. Quantitative real-time RT-PCR analysis showed that knocking down of Smad4 substantially inhibited both AdBMP2-induced and basal expression levels of cardiac transcription factors GATA4 and Nkx2.5, but not MEF2c and Tbx5. Similarly, chromatin immunoprecipitation (ChIP) analysis showed that knocking down of Smad4 inhibited both AdBMP2-induced and basal histone H3 acetylation levels in the promoter regions of GATA4 and Nkx2.5, but not of Tbx5 and MEF2c. In addition, Lv-Smad4 selectively suppressed AdBMP2-induced expression of HAT p300, but not of HAT GCN5 in H9c2 cells. The data indicated that inhibition of Smad4 diminished both AdBMP2 induced and basal histone acetylation levels in the promoter regions of

  7. The STAR protein QKI-7 recruits PAPD4 to regulate post-transcriptional polyadenylation of target mRNAs

    OpenAIRE

    Yamagishi, Ryota; Tsusaka, Takeshi; Mitsunaga, Hiroko; Maehata, Takaharu; Hoshino, Shin-ichi

    2016-01-01

    Emerging evidence has demonstrated that regulating the length of the poly(A) tail on an mRNA is an efficient means of controlling gene expression at the post-transcriptional level. In early development, transcription is silenced and gene expression is primarily regulated by cytoplasmic polyadenylation. In somatic cells, considerable progress has been made toward understanding the mechanisms of negative regulation by deadenylation. However, positive regulation through elongation of the poly(A)...

  8. LIN28 phosphorylation by MAPK/ERK couples signaling to the post-transcriptional control of pluripotency

    Science.gov (United States)

    Tsanov, Kaloyan M.; Pearson, Daniel S.; Wu, Zhaoting; Han, Areum; Triboulet, Robinson; Seligson, Marc T.; Powers, John T.; Osborne, Jihan K.; Kane, Susan; Gygi, Steven P.; Gregory, Richard I.; Daley, George Q.

    2016-01-01

    Signaling and post-transcriptional gene control are both critical for the regulation of pluripotency1,2, yet how they are integrated to influence cell identity remains poorly understood. LIN28 (also known as LIN28A), a highly conserved RNA-binding protein (RBP), has emerged as a central post-transcriptional regulator of cell fate through blockade of let-7 microRNA (miRNA) biogenesis and direct modulation of mRNA translation3. Here we show that LIN28 is phosphorylated by MAPK/ERK in pluripotent stem cells (PSCs), which increases its levels via post-translational stabilization. LIN28 phosphorylation had little impact on let-7 but enhanced LIN28’s effect on its direct mRNA targets, revealing a mechanism that uncouples LIN28’s let-7-dependent and independent activities. We have linked this mechanism to the induction of pluripotency by somatic cell reprogramming and the transition from naïve to primed pluripotency. Collectively, our findings indicate that MAPK/ERK directly impacts LIN28, defining an axis that connects signaling, post-transcriptional gene control, and cell fate regulation. PMID:27992407

  9. The post-transcriptional regulatory system CSR controls the balance of metabolic pools in upper glycolysis of Escherichia coli.

    Science.gov (United States)

    Morin, Manon; Ropers, Delphine; Letisse, Fabien; Laguerre, Sandrine; Portais, Jean-Charles; Cocaign-Bousquet, Muriel; Enjalbert, Brice

    2016-05-01

    Metabolic control in Escherichia coli is a complex process involving multilevel regulatory systems but the involvement of post-transcriptional regulation is uncertain. The post-transcriptional factor CsrA is stated as being the only regulator essential for the use of glycolytic substrates. A dozen enzymes in the central carbon metabolism (CCM) have been reported as potentially controlled by CsrA, but its impact on the CCM functioning has not been demonstrated. Here, a multiscale analysis was performed in a wild-type strain and its isogenic mutant attenuated for CsrA (including growth parameters, gene expression levels, metabolite pools, abundance of enzymes and fluxes). Data integration and regulation analysis showed a coordinated control of the expression of glycolytic enzymes. This also revealed the imbalance of metabolite pools in the csrA mutant upper glycolysis, before the phosphofructokinase PfkA step. This imbalance is associated with a glucose-phosphate stress. Restoring PfkA activity in the csrA mutant strain suppressed this stress and increased the mutant growth rate on glucose. Thus, the carbon storage regulator system is essential for the effective functioning of the upper glycolysis mainly through its control of PfkA. This work demonstrates the pivotal role of post-transcriptional regulation to shape the carbon metabolism. © 2016 John Wiley & Sons Ltd.

  10. Retinal and choroidal expression of BMP-2 in lens-induced myopia and recovery from myopia in guinea pigs.

    Science.gov (United States)

    Li, Honghui; Wu, Juan; Cui, Dongmei; Zeng, Junwen

    2016-03-01

    The present study investigated the retinal and choroidal expression of bone morphogenetic protein-2 (BMP-2) in myopia and in myopia recovery in a guinea pig model. For this investigation, two groups of guinea pigs, lens‑induced myopia and recovery from myopia, were used, and defocused myopia was induced the guinea pigs wearing ‑4.00 D lenses on the right eyes for 3 weeks, with the left eyes serving as the contralateral. In the following week, the lenses of the guinea pigs in the recovery group were removed, and the refractive power and axial length were measured. The expression of BMP‑2 in the eyeballs was observed using immunohistochemistry and analyzed using Western blot analysis. After 3 weeks, the eyes acquired relative myopia and longer axial lengths in the two groups of guinea pigs. After 1 week without lenses in the recovery group, the myopia and axial lengths regressed. Immunofluorescence staining showed that BMP‑2 was expressed in the posterior retina, RPE, choroid and sclera. The expression of BMP‑2 decreased in the myopic retina of the guinea pigs. Following the regression of myopia in the recovery group, no difference in the expression of BMP‑2 was observed between the recovered treated eyes and the contralateral eyes. The choroidal expression level of BMP‑2 in the treated eyes showed no significant changes in either group. Therefore, BMP‑2 may be involved in the development of myopia, however, it does not have a primary role in the retinal and choroidal signals regulating scleral remodeling.

  11. Osteogenesis differentiation of human periodontal ligament cells by CO2 laser-treatment stimulating macrophages via BMP2 signalling pathway

    International Nuclear Information System (INIS)

    Hsieh, Wen-Hui; Chen, Yi-Jyun; Hung, Chi-Jr; Huang, Tsui-Hsien; Kao, Chia-Tze; Shie, Ming-You

    2014-01-01

    Immune reactions play an important role in determining the biostimulation of bone formation, either in new bone formation or inflammatory fibrous tissue encapsulation. Macrophage cell, the important effector cells in the immune reaction, which are indispensable for osteogenesis and their heterogeneity and plasticity, render macrophages a primer target for immune system modulation. However, there are very few studies about the effects of macrophage cells on laser treatment-regulated osteogenesis. In this study, we used CO 2 laser as a model biostimulation to investigate the role of macrophage cells on the CO 2 laser stimulated osteogenesis. Bone morphogenetic protein 2 (BMP2) was also significantly up regulated by the CO 2 laser stimulation, indicating that macrophage may participate in the CO 2 laser stimulated osteogenesis. Interestingly, when laser treatment macrophage-conditioned medium were applied to human periodontal ligament cells (hPDLs), the osteogenesis differentiation of hPDLs was significantly enhanced, indicating the important role of macrophages in CO 2 laser-induced osteogenesis. These findings provided valuable insights into the mechanism of CO 2 laser-stimulated osteogenic differentiation, and a strategy to optimize the evaluation system for the in vitro osteogenesis capacity of laser treatment. (paper)

  12. TGF-ß1 enhances the BMP-2-induced chondrogenesis of bovine synovial explants and arrests downstream differentiation at an early stage of hypertrophy.

    Science.gov (United States)

    Shintani, Nahoko; Siebenrock, Klaus A; Hunziker, Ernst B

    2013-01-01

    Synovial explants furnish an in-situ population of mesenchymal stem cells for the repair of articular cartilage. Although bone morphogenetic protein 2 (BMP-2) induces the chondrogenesis of bovine synovial explants, the cartilage formed is neither homogeneously distributed nor of an exclusively hyaline type. Furthermore, the downstream differentiation of chondrocytes proceeds to the stage of terminal hypertrophy, which is inextricably coupled with undesired matrix mineralization. With a view to optimizing BMP-2-induced chondrogenesis, the modulating influences of fibroblast growth factor 2 (FGF-2) and transforming growth factor beta 1 (TGF-ß1) were investigated. Explants of bovine calf metacarpal synovium were exposed to BMP-2 (200 ng/ml) for 4 (or 6) weeks. FGF-2 (10 ng/ml) or TGF-ß1 (10 ng/ml) was introduced at the onset of incubation and was present either during the first week of culturing alone or throughout its entire course. FGF-2 enhanced the BMP-2-induced increase in metachromatic staining for glycosaminoglycans (GAGs) only when it was present during the first week of culturing alone. TGF-ß1 enhanced not only the BMP-2-induced increase in metachromasia (to a greater degree than FGF-2), but also the biochemically-assayed accumulation of GAGs, when it was present throughout the entire culturing period; in addition, it arrested the downstream differentiation of cells at an early stage of hypertrophy. These findings were corroborated by an analysis of the gene- and protein-expression levels of key cartilaginous markers and by an estimation of individual cell volume. TGF-ß1 enhances the BMP-2-induced chondrogenesis of bovine synovial explants, improves the hyaline-like properties of the neocartilage, and arrests the downstream differentiation of cells at an early stage of hypertrophy. With the prospect of engineering a mature, truly articular type of cartilage in the context of clinical repair, our findings will be of importance in fine-tuning the

  13. Evaluation of a Novel HA/ZrO2-Based Porous Bioceramic Artificial Vertebral Body Combined with a rhBMP-2/Chitosan Slow-Release Hydrogel.

    Directory of Open Access Journals (Sweden)

    Yihui Shi

    Full Text Available A new HA/ZrO2-based porous bioceramic artificial vertebral body (AVB, carried a recombinant human bone morphogenetic protein-2 (rhBMP-2/chitosan slow-release hydrogel was prepared to repair vertebral bone defect in beagles. An ionic cross-linking was used to prepare the chitosan hydrogel (CS gel as the rhBMP-2 slow-release carrier. The vertebral body defects were implanted with the rhBMP-2-loaded AVB in group A, or a non-drug-loaded AVB in group B, or autologous iliac in group C. The encapsulation rate of rhBMP-2 in rhBMP-2-loaded CS gel was 91.88±1.53%, with a drug load of 39.84±2.34 ng/mg. At 6, 12, 24 weeks postoperatively, radiography showed that the bone calluses gradually increased with time in group A, where the artificial vertebral body had completely fused with host-bone at 24 weeks after surgery. In group C, an apparent bone remodeling was occurred in the early stages, and the graft-bone and host-bone had also fused completely at 24 weeks postoperatively. In group B, fusion occurred less than in groups A and C. At 24 weeks after surgery, micro-computed tomography (Micro-CT revealed that the volume of newly-formed bone in group A was significantly more than in group B (p<0.05. At 24 weeks after surgery, ultra-compressive strengths of the operated segments were 14.03±1.66 MPa in group A, 8.62±1.24 MPa in group B, and 13.78±1.43 MPa in group C. Groups A and C were both significantly higher than group B (p < 0.05. At 24 weeks postoperatively, the hard tissue sections showed that the AVB of group A had tightly fused with host bone, and that pores of the AVB had been filled with abundant nearly mature bone, and that the new bone structured similarly to a trabecular framework, which was similar to that in group C. In contrast, implant fusion of the AVB in group B was not as apparent as group A. In conclusion, the novel HA/ZrO2-based porous bioceramic AVB carried the rhBMP-2-loaded CS gel can promote the repair of bony defect, and induce

  14. TGF-ß1 enhances the BMP-2-induced chondrogenesis of bovine synovial explants and arrests downstream differentiation at an early stage of hypertrophy.

    Directory of Open Access Journals (Sweden)

    Nahoko Shintani

    Full Text Available Synovial explants furnish an in-situ population of mesenchymal stem cells for the repair of articular cartilage. Although bone morphogenetic protein 2 (BMP-2 induces the chondrogenesis of bovine synovial explants, the cartilage formed is neither homogeneously distributed nor of an exclusively hyaline type. Furthermore, the downstream differentiation of chondrocytes proceeds to the stage of terminal hypertrophy, which is inextricably coupled with undesired matrix mineralization. With a view to optimizing BMP-2-induced chondrogenesis, the modulating influences of fibroblast growth factor 2 (FGF-2 and transforming growth factor beta 1 (TGF-ß1 were investigated.Explants of bovine calf metacarpal synovium were exposed to BMP-2 (200 ng/ml for 4 (or 6 weeks. FGF-2 (10 ng/ml or TGF-ß1 (10 ng/ml was introduced at the onset of incubation and was present either during the first week of culturing alone or throughout its entire course. FGF-2 enhanced the BMP-2-induced increase in metachromatic staining for glycosaminoglycans (GAGs only when it was present during the first week of culturing alone. TGF-ß1 enhanced not only the BMP-2-induced increase in metachromasia (to a greater degree than FGF-2, but also the biochemically-assayed accumulation of GAGs, when it was present throughout the entire culturing period; in addition, it arrested the downstream differentiation of cells at an early stage of hypertrophy. These findings were corroborated by an analysis of the gene- and protein-expression levels of key cartilaginous markers and by an estimation of individual cell volume.TGF-ß1 enhances the BMP-2-induced chondrogenesis of bovine synovial explants, improves the hyaline-like properties of the neocartilage, and arrests the downstream differentiation of cells at an early stage of hypertrophy. With the prospect of engineering a mature, truly articular type of cartilage in the context of clinical repair, our findings will be of importance in fine-tuning the

  15. Organization and post-transcriptional processing of focal adhesion kinase gene

    Directory of Open Access Journals (Sweden)

    Enslen Hervé

    2006-08-01

    Full Text Available Abstract Background Focal adhesion kinase (FAK is a non-receptor tyrosine kinase critical for processes ranging from embryo development to cancer progression. Although isoforms with specific molecular and functional properties have been characterized in rodents and chicken, the organization of FAK gene throughout phylogeny and its potential to generate multiple isoforms are not well understood. Here, we study the phylogeny of FAK, the organization of its gene, and its post-transcriptional processing in rodents and human. Results A single orthologue of FAK and the related PYK2 was found in non-vertebrate species. Gene duplication probably occurred in deuterostomes after the echinoderma embranchment, leading to the evolution of PYK2 with distinct properties. The amino acid sequence of FAK and PYK2 is conserved in their functional domains but not in their linker regions, with the absence of autophosphorylation site in C. elegans. Comparison of mouse and human FAK genes revealed the existence of multiple combinations of conserved and non-conserved 5'-untranslated exons in FAK transcripts suggesting a complex regulation of their expression. Four alternatively spliced coding exons (13, 14, 16, and 31, previously described in rodents, are highly conserved in vertebrates. Cis-regulatory elements known to regulate alternative splicing were found in conserved alternative exons of FAK or in the flanking introns. In contrast, other reported human variant exons were restricted to Homo sapiens, and, in some cases, other primates. Several of these non-conserved exons may correspond to transposable elements. The inclusion of conserved alternative exons was examined by RT-PCR in mouse and human brain during development. Inclusion of exons 14 and 16 peaked at the end of embryonic life, whereas inclusion of exon 13 increased steadily until adulthood. Study of various tissues showed that inclusion of these exons also occurred, independently from each other, in a

  16. Efficacy of rhBMP-2 loaded PCL/PLGA/β-TCP guided bone regeneration membrane fabricated by 3D printing technology for reconstruction of calvaria defects in rabbit

    International Nuclear Information System (INIS)

    Shim, Jin-Hyung; Jeong, Chang-Mo; Huh, Jung-Bo; Jang, Jinah; Jeong, Sung-In; Cho, Dong-Woo; Yoon, Min-Chul

    2014-01-01

    We successfully fabricated a three-dimensional (3D) printing-based PCL/PLGA/β-TCP guided bone regeneration (GBR) membrane that slowly released rhBMP-2. To impregnate the GBR membrane with intact rhBMP-2, collagen solution encapsulating rhBMP-2 (5 µg ml −1 ) was infused into pores of a PCL/PLGA/β-TCP membrane constructed using a 3D printing system with four dispensing heads. In a release profile test, sustained release of rhBMP-2 was observed for up to 28 d. To investigate the efficacy of the GBR membrane on bone regeneration, PCL/PLGA/β-TCP membranes with or without rhBMP-2 were implanted in an 8 mm calvaria defect of rabbits. Bone formation was evaluated at weeks 4 and 8 histologically and histomorphometrically. A space making ability of the GBR membrane was successfully maintained in both groups, and significantly more new bone was formed at post-implantation weeks 4 and 8 by rhBMP-2 loaded GBR membranes. Interestingly, implantation with rhBMP-2 loaded GBR membranes led to almost entire healing of calvaria defects within 8 weeks. (paper)

  17. TGF-β1, GDF-5, and BMP-2 stimulation induces chondrogenesis in expanded human articular chondrocytes and marrow-derived stromal cells.

    Science.gov (United States)

    Murphy, Meghan K; Huey, Daniel J; Hu, Jerry C; Athanasiou, Kyriacos A

    2015-03-01

    Replacement of degenerated cartilage with cell-based cartilage products may offer a long-term solution to halt arthritis' degenerative progression. Chondrocytes are frequently used in cell-based FDA-approved cartilage products; yet human marrow-derived stromal cells (hMSCs) show significant translational potential, reducing donor site morbidity and maintaining their undifferentiated phenotype with expansion. This study sought to investigate the effects of transforming growth factor β1 (TGF-β1), growth/differentiation factor 5 (GDF-5), and bone morphogenetic protein 2 (BMP-2) during postexpansion chondrogenesis in human articular chondrocytes (hACs) and to compare chondrogenesis in passaged hACs with that of passaged hMSCs. Through serial expansion, chondrocytes dedifferentiated, decreasing expression of chondrogenic genes while increasing expression of fibroblastic genes. However, following expansion, 10 ng/mL TGF-β1, 100 ng/mL GDF-5, or 100 ng/mL BMP-2 supplementation during three-dimensional aggregate culture each upregulated one or more markers of chondrogenic gene expression in both hACs and hMSCs. Additionally, in both cell types, the combination of TGF-β1, GDF-5, and BMP-2 induced the greatest upregulation of chondrogenic genes, that is, Col2A1, Col2A1/Col1A1 ratio, SOX9, and ACAN, and synthesis of cartilage-specific matrix, that is, glycosaminoglycans (GAGs) and ratio of collagen II/I. Finally, TGF-β1, GDF-5, and BMP-2 stimulation yielded mechanically robust cartilage rich in collagen II and GAGs in both cell types, following 4 weeks maturation. This study illustrates notable success in using the self-assembling method to generate robust, scaffold-free neocartilage constructs using expanded hACs and hMSCs. © 2014 AlphaMed Press.

  18. Expression of the bone morphogenetic protein-2 (BMP2 in the human cumulus cells as a biomarker of oocytes and embryo quality

    Directory of Open Access Journals (Sweden)

    Sirin B Demiray

    2017-01-01

    Full Text Available Background: The members of the transforming growth factor-B superfamily, as the bone morphogenetic proteins (BMPs subfamily and anti-Müllerian hormone (AMH, play a role during follicular development, and the bone morphogenetic protein-2 (BMP2, AMH, and THY1 are expressed in ovaries. Aim: This study was designed to define whether or not the expressions of these proteins in human cumulus cells (CCs can be used as predictors of the oocyte and embryo competence. Settings and Design: The study included nine female patients who were diagnosed as idiopathic infertility, aged 25–33 years (median 30 years and underwent Assisted Reproductive Technologies. Materials and Methods: The CCs from 60 oocyte–cumulus complexes obtained from the nine patients were evaluated with immunofluorescence staining in respect of BMPs, AMH and THY1 markers. The CCs surrounding the same oocytes were evaluated separately according to the oocyte and embryo quality. Statistical Analysis: Quantitative data were statistically analyzed for differences using the two-sided Mann–Whitney U test (P < 0.05. Results and Conclusions: Significant differences in immunofluorescence staining were observed in oocyte quality and embryo quality for the BMP2 only (P < 0.05. No significant differences were observed for AMH or CD90/THY1. Conclusion: These results demonstrated that there is a significant difference in the expression of BMP2 in the CCs of good quality oocytes and subsequently a good embryo.

  19. Delta-like 1/fetal antigen 1(DLK1/FA1) inhibits BMP2 induced osteoblast differentiation through modulation of NFκB signaling pathway

    DEFF Research Database (Denmark)

    Qiu, Weimin; Abdallah, Basem; Kassem, Moustapha

    DLK1/FA1 (delta-like 1/fetal antigen-1) is a negative regulator of bone mass that acts to inhibit osteoblast differentiation and stimulate osteoclast differentiation. However, the molecular mechanisms underlying these effects are not known. Thus, we studied the effect of DLK1/FA1 on different...... osteogenic factors-induced osteoblast differentiation. We identified DLK1/FA1 as an inhibitor of BMP2-induced osteogenesis in mouse myoblast C2C12 cells. Stable overexpression of DLK1/FA1 in C2C12 cells or the addition of its soluble form protein FA1 significantly inhibited BMP2-induced osteogenesis...... as assessed by reduced Alp activity and osteogenic gene expression including Alp, Col1a1, Runx2 and Bglap. In addition, DLK1/FA1 inhibited BMP signaling as demonstrated by reduced gene expression of BMP-responsive genes: Junb and Id1, reduced BMP2 induced luciferase activity in C2C12 BMP luciferase reporter...

  20. Effects of piezosurgery in accelerating the movement of orthodontic alveolar bone tooth of rats and the expression mechanism of BMP-2.

    Science.gov (United States)

    Han, Jinyou; He, Hong

    2016-11-01

    The aim of the study was to investigate the effects of piezosurgery in accelerating the movement of orthodontic alveolar bone tooth of rats and the expression mechanism of bone morphogenetic protein-2 (BMP-2). Adult male Wistar rats (n=30), with an age range of 14-15 weeks, and an average weight of 250±16 g were used. The animals were randomly divided into the control and observation groups. The rats in the control group were injected with 25-dihydroxyvitamin (1,25-dihydroxycholecalciferol) into their dental ligament. The rats in the observation group were placed with an orthodontic device between the first molar and central incisor in the maxillary. On the first day after animal treatment, piezosurgery stimulation was performed on the first molar in maxillary. The changes of the movement distance of the first molar and gum surface temperature on days 1, 3, 5, 7 and 14 were then compared. Immunohistochemical staining was performed to detect the expression of BMP-2 of periodontal tissue in the tension side of the first molar. Tooth movement distance in the observation group on days 5, 7 and 14 was significantly longer than that in the control group (ppiezosurgery may significantly accelerate the movement of orthodontic alveolar bone tooth of rats and be associated with an increasing BMP-2 expression.

  1. The effect of a slow mode of BMP-2 delivery on the inflammatory response provoked by bone-defect-filling polymeric scaffolds.

    Science.gov (United States)

    Wu, Gang; Liu, Yuelian; Iizuka, Tateyuki; Hunziker, Ernst Bruno

    2010-10-01

    We investigated the inflammatory response to, and the osteoinductive efficacies of, four polymers (collagen, Ethisorb, PLGA and Polyactive) that bore either an adsorbed (fast-release kinetics) or a calcium-phosphate-coating-incorporated (slow-release kinetics) depot of BMP-2. Titanium-plate-supported discs of each polymer (n = 6 per group) were implanted at an ectopic (subcutaneous) ossification site in rats (n = 48). Five weeks later, they were retrieved for a histomorphometric analysis of the volumes of ectopic bone and foreign-body giant cells (a gauge of inflammatory reactivity), and the degree of polymer degradation. For each polymer, the osteoinductive efficacy of BMP-2 was higher when it was incorporated into a coating than when it was directly adsorbed onto the material. This mode of BMP-2 carriage was consistently associated with an attenuation of the inflammatory response. For coated materials, the volume density of foreign-body giant cells was inversely correlated with the volume density of bone (r(2) = 0.96), and the volume density of bone was directly proportional to the surface-area density of the polymer (r(2) = 0.97). Following coating degradation, other competitive factors, such as the biocompatibility and the biodegradability of the polymer itself, came into play. 2010 Elsevier Ltd. All rights reserved.

  2. Conditions Inducing Excessive O-GlcNAcylation Inhibit BMP2-Induced Osteogenic Differentiation of C2C12 Cells.

    Science.gov (United States)

    Gu, Hanna; Song, Mina; Boonanantanasarn, Kanitsak; Baek, Kyunghwa; Woo, Kyung Mi; Ryoo, Hyun-Mo; Baek, Jeong-Hwa

    2018-01-09

    Hyperglycemic conditions in diabetic patients can affect various cellular functions, including the modulation of osteogenic differentiation. However, the molecular mechanisms by which hyperglycemia affects osteogenic differentiation are yet to be clarified. This study aimed to investigate whether the aberrant increase in protein O -linked-β- N -acetylglucosamine glycosylation ( O -GlcNAcylation) contributes to the suppression of osteogenic differentiation due to hyperglycemia. To induce osteogenic differentiation, C2C12 cells were cultured in the presence of recombinant human bone morphogenetic protein 2 (BMP2). Excessive protein O -GlcNAcylation was induced by treating C2C12 cells with high glucose, glucosamine, or N -acetylglucosamine concentrations or by O -GlcNAc transferase (OGT) overexpression. The effect of O -GlcNAcylation on osteoblast differentiation was then confirmed by examining the expression levels of osteogenic marker gene mRNAs, activity of alkaline phosphatase, and transcriptional activity of Runx2, a critical transcription factor for osteoblast differentiation and bone formation. Cell treatment with high glucose, glucosamine or N -acetylglucosamine increased O -GlcNAcylation of Runx2 and the total levels of O -GlcNAcylated proteins, which led to a decrease in the transcriptional activity of Runx2, expression levels of osteogenic marker genes (Runx2, osterix, alkaline phosphatase, and type I collagen), and activity of alkaline phosphatase. These inhibitory effects were rescued by lowering protein O -GlcNAcylation levels by adding STO45849, an OGT inhibitor, or by overexpressing β- N -acetylglucosaminidase. Our findings suggest that excessive protein O -GlcNAcylation contributes to high glucose-suppressed osteogenic differentiation.

  3. The effect of core decompression on local expression of BMP-2, PPAR-γ and bone regeneration in the steroid-induced femoral head osteonecrosis

    Directory of Open Access Journals (Sweden)

    Wang Wei

    2012-08-01

    Full Text Available Abstract Background To investigate the efficacy of the sole core decompression surgery for the treatment of steroid-induced femoral head osteonecrosis. Methods The model was established by administration of steroids in combination with horse serum. The rabbits with bilateral femoral head osteonecrosis were randomly selected to do the one side of core decompression. The other side was used as the sham. Quantitative RT-PCR and western blot techniques were used to measure the local expression of BMP-2 and PPAR-γ. Bone tissues from control and operation groups were histologically analyzed by H&E staining. The comparisons of the local expression of BMP-2 and PPAR-γ and the bone regeneration were further analyzed between different groups at each time point. Results The expression of BMP-2 in the osteonecrosis femoral head with or without decompression was significantly lower than that in normal animals. BMP-2 expression both showed the decreasing trend with the increased post-operation time. No significant difference of BMP-2 expression occurred between femoral head osteonecrosis with and without decompression. The PPAR-γ expression in the femoral head osteonecrosis with and without core decompression both was significantly higher than that in control. Its expression pattern showed a significantly increased trend with increased the post-operation time. However, there was no significant difference of PPAR-γ expression between the femoral head osteonecrosis with and without decompression at each time point. Histopathological analysis revealed that new trabecular bone and a large number of osteoblasts were observed in the steroid-induced femoral head osteonecrosis with lateral decompression at 8 weeks after surgery, but there still existed trabecular bone fractures and bone necrosis. Conclusions Although decompression takes partial effect in promoting bone regeneration in the early treatment of femoral head osteonecrosis, such an effect does not

  4. Post-transcriptional generation of miRNA variants by multiple nucleotidyl transferases contributes to miRNA transcriptome complexity

    OpenAIRE

    Wyman, Stacia K.; Knouf, Emily C.; Parkin, Rachael K.; Fritz, Brian R.; Lin, Daniel W.; Dennis, Lucas M.; Krouse, Michael A.; Webster, Philippa J.; Tewari, Muneesh

    2011-01-01

    Modification of microRNA sequences by the 3′ addition of nucleotides to generate so-called “isomiRs” adds to the complexity of miRNA function, with recent reports showing that 3′ modifications can influence miRNA stability and efficiency of target repression. Here, we show that the 3′ modification of miRNAs is a physiological and common post-transcriptional event that shows selectivity for specific miRNAs and is observed across species ranging from C. elegans to human. The modifications resul...

  5. Quinoline compound KM11073 enhances BMP-2-dependent osteogenic differentiation of C2C12 cells via activation of p38 signaling and exhibits in vivo bone forming activity.

    Directory of Open Access Journals (Sweden)

    Seung-hwa Baek

    Full Text Available Recombinant human bone morphogenetic protein (rhBMP-2 has been approved by the FDA for clinical application, but its use is limited due to high cost and a supra-physiological dose for therapeutic efficacy. Therefore, recent studies have focused on the generation of new therapeutic small molecules to induce bone formation or potentiate the osteogenic activity of BMP-2. Here, we show that [4-(7-chloroquinolin-4-yl piperazino][1-phenyl-5-(trifluoromethyl-1H-pyrazol-4-yl]methanone (KM11073 strongly enhances the BMP-2-stimulated induction of alkaline phosphatase (ALP, an early phase biomarker of osteoblast differentiation, in bi-potential mesenchymal progenitor C2C12 cells. The KM11073-mediated ALP induction was inhibited by the BMP antagonist noggin, suggesting that its osteogenic activity occurs via BMP signaling. In addition, a pharmacological inhibition study suggested the involvement of p38 activation in the osteogenic action of KM11073 accompanied by enhanced expression of BMP-2, -6, and -7 mRNA. Furthermore, the in vivo osteogenic activity of KM11073 was confirmed in zebrafish and mouse calvarial bone formation models, suggesting the possibility of its single use for bone formation. In conclusion, the combination of rhBMP-2 with osteogenic small molecules could reduce the use of expensive rhBMP-2, mitigating the undesirable side effects of its supra-physiological dose for therapeutic efficacy. Moreover, due to their inherent physical properties, small molecules could represent the next generation of regenerative medicine.

  6. Post-Transcriptional Control of Gene Expression in Mouse Early Embryo Development: A View from the Tip of the Iceberg

    Directory of Open Access Journals (Sweden)

    Claudio Sette

    2011-04-01

    Full Text Available Fertilization is a very complex biological process that requires the perfect cooperation between two highly specialized cells: the male and female gametes. The oocyte provides the physical space where this process takes place, most of the energetic need, and half of the genetic contribution. The spermatozoon mostly contributes the other half of the chromosomes and it is specialized to reach and to penetrate the oocyte. Notably, the mouse oocyte and early embryo are transcriptionally inactive. Hence, they fully depend on the maternal mRNAs and proteins stored during oocyte maturation to drive the onset of development. The new embryo develops autonomously around the four-cell stage, when maternal supplies are exhausted and the zygotic genome is activated in mice. This oocyte-to-embryo transition needs an efficient and tightly regulated translation of the maternally-inherited mRNAs, which likely contributes to embryonic genome activation. Full understanding of post-transcriptional regulation of gene expression in early embryos is crucial to understand the reprogramming of the embryonic genome, it might help driving reprogramming of stem cells in vitro and will likely improve in vitro culturing of mammalian embryos for assisted reproduction. Nevertheless, the knowledge of the mechanism(s underlying this fundamental step in embryogenesis is still scarce, especially if compared to other model organisms. We will review here the current knowledge on the post-transcriptional control of gene expression in mouse early embryos and discuss some of the unanswered questions concerning this fascinating field of biology.

  7. Acellular dermal matrix loading with bFGF achieves similar acceleration of bone regeneration to BMP-2 via differential effects on recruitment, proliferation and sustained osteodifferentiation of mesenchymal stem cells

    International Nuclear Information System (INIS)

    Du, Mi; Zhu, Ting; Duan, Xiaoqi; Ge, Shaohua; Li, Ning; Sun, Qinfeng; Yang, Pishan

    2017-01-01

    New generation of barrier membranes has been developed, which not only act as barriers but also as delivery devices to release specific growth factors. This study observed biological behaviors of bone morrow mesenchymal stem cells (BMMSCs) pretreated by bFGF or BMP-2 in vitro and evaluated differential bone regeneration process induced by bFGF and BMP-2 loaded acellular dermal matrix (ADM) membrane using critical-size rat calvarial defect model in vivo. The results showed that the proliferation capability of BMMSCs pretreated by bFGF was stronger than that by BMP-2, while there was temporally differential effect of bFGF and BMP-2 pretreatment on MSC osteogenic differentiation potentials. During healing process of rat calvarial defects, 2-fold more CD34 −/CD90 + MSCs in group of bFGF-ADM was observed than in any other treatment group at 2 weeks. However, there were similar amount of new bone formation and expression of osteopotin in newly-formed bone tissue in groups of bFGF- and BMP-2-ADM at 8 weeks, which were more than those in ADM alone and blank control. Taken together, bFGF-ADM guided similar bone regeneration to BMP-2 through more efficient recruitment of MSCs, and moreover, BMMSCs pretreated by bFGF showed stronger proliferation at 1–5 days and osteogenic differentiation potentials at 14 days compared with BMP-2 pretreatment. - Highlights: • An improved barrier membrane used in the field of bone tissue engineering was proposed, which is acellular dermal matrix (ADM) loaded with growth factors. • It is generally agreed that BMP-2 and -7 provide the greatest bone regeneration potentials, however, we found that ADM loading with bFGF could guide similar bone regeneration to BMP-2. • Compared with BMP-2, bFGF could more effectively recruit MSCs and moreover, BMMSCs pretreated by bFGF showed out stronger proliferation at 1-5 days and osteogenic differentiation potentials at 14 days.

  8. Generation of an rhBMP-2-loaded beta-tricalcium phosphate/hydrogel composite and evaluation of its efficacy on peri-implant bone formation

    International Nuclear Information System (INIS)

    Lee, Jae Hyup; Baek, Hae-Ri; Lee, Ji-Ho; Ryu, Mi Young; Seo, Jun-Hyuk; Lee, Kyung-Mee

    2014-01-01

    Dental implant insertion on a site with low bone quality or bone defect should be preceded by a bone graft or artificial bone graft insertion to heal the defect. We generated a beta-tricalcium phosphate (β-TCP) and poloxamer 407-based hydrogel composite and penetration of the β-TCP/hydrogel composite into the peri-implant area of bone was evaluated by porous bone block experiments. The maximum penetration depth for porous bone blocks and dense bone blocks were 524 μm and 464 μm, respectively. We report the in-vivo performance of a composite of β-TCP/hydrogel composite as a carrier of recombinant human bone morphogenetic protein (rhBMP-2), implanted into a rabbit tibial defect model. Three holes drilled into each tibia of eight male rabbits were (1) grafted with dental implant fixtures; (2) filled with β-TCP/hydrogel composite (containing 5 μg of rhBMP-2), followed by grafting of the dental implant fixtures. Four weeks later, bone-implant contact ratio and peri-implant bone formation were analyzed by radiography, micro-CT and histology of undecalcified specimens. The micro-CT results showed a significantly higher level of trabecular thickness and new bone and peri-implant new bone formation in the experimental treatment compared to the control treatment. Histomorphometry revealed a significantly higher bone-implant contact ratio and peri-implant bone formation with the experimental treatment. The use of β-TCP/poloxamer 407 hydrogel composite as a carrier of rhBMP-2 significantly promoted new bone formation around the dental implant fixture and it also improved the quality of the new bone formed in the tibial marrow space. (paper)

  9. S100A4 and BMP-2 Co-Dependently Induce Vascular Smooth Muscle Cell Migration via pERK and Chloride Intracellular Channel 4 (CLIC4)

    Science.gov (United States)

    Spiekerkoetter, Edda; Guignabert, Christophe; de Jesus Perez, Vinicio; Alastalo, Tero-Pekka; Powers, Janine M; Wang, Lingli; Lawrie, Allan; Ambartsumian, Noona; Schmidt, Ann-Marie; Berryman, Mark; Ashley, Richard H; Rabinovitch, Marlene

    2009-01-01

    Rationale S100A4/Mts1 is implicated in motility of human pulmonary artery smooth muscle cells (hPASMC), through an interaction with the receptor for advanced glycation end products (RAGE). Objective We hypothesized that S100A4/Mts1-mediated hPASMC motility might be enhanced by loss of function of bone morphogenetic protein (BMP) receptor (R) II, observed in pulmonary arterial hypertension (PAH). Methods and Results Both S100A4/Mts1 (500ng/ml) and BMP-2 (10ng/ml) induce migration of hPASMCS in a novel co-dependent manner, in that the response to either ligand is lost with anti-RAGE or BMPRII siRNA. Phosphorylation of ERK is induced by both ligands and is required for motility by inducing MMP2 activity, but phosphoERK1/2 is blocked by anti-RAGE and not by BMPRII siRNA. In contrast, BMPRII siRNA, but not anti-RAGE, reduces expression of intracellular chloride channel 4 (CLIC4), a scaffolding molecule necessary for motility in response to S100A4/Mts1 or BMP-2. Reduced CLIC4 expression does not interfere with S100A4/Mts1 internalization or its interaction with myosin heavy chain IIA (MHCIIA), but does alter alignment of MHCIIA and actin filaments creating the appearance of vacuoles. This abnormality is associated with reduced peripheral distribution and/or delayed activation of RhoA and Rac1, small GTPases required for retraction and extension of lamellipodiae in motile cells. Conclusions Our studies demonstrate how a single ligand (BMP-2 or S100A4/Mts1) can recruit multiple cell surface receptors to relay signals that coordinate events culminating in a functional response, i.e., cell motility. We speculate that this carefully controlled process limits signals from multiple ligands, but could be subverted in disease. PMID:19713532

  10. The multifaceted effects of agmatine on functional recovery after spinal cord injury through Modulations of BMP-2/4/7 expressions in neurons and glial cells.

    Directory of Open Access Journals (Sweden)

    Yu Mi Park

    Full Text Available Presently, few treatments for spinal cord injury (SCI are available and none have facilitated neural regeneration and/or significant functional improvement. Agmatine (Agm, a guanidinium compound formed from decarboxylation of L-arginine by arginine decarboxylase, is a neurotransmitter/neuromodulator and been reported to exert neuroprotective effects in central nervous system injury models including SCI. The purpose of this study was to demonstrate the multifaceted effects of Agm on functional recovery and remyelinating events following SCI. Compression SCI in mice was produced by placing a 15 g/mm(2 weight for 1 min at thoracic vertebra (Th 9 segment. Mice that received an intraperitoneal (i.p. injection of Agm (100 mg/kg/day within 1 hour after SCI until 35 days showed improvement in locomotor recovery and bladder function. Emphasis was made on the analysis of remyelination events, neuronal cell preservation and ablation of glial scar area following SCI. Agm treatment significantly inhibited the demyelination events, neuronal loss and glial scar around the lesion site. In light of recent findings that expressions of bone morphogenetic proteins (BMPs are modulated in the neuronal and glial cell population after SCI, we hypothesized whether Agm could modulate BMP- 2/4/7 expressions in neurons, astrocytes, oligodendrocytes and play key role in promoting the neuronal and glial cell survival in the injured spinal cord. The results from computer assisted stereological toolbox analysis (CAST demonstrate that Agm treatment dramatically increased BMP- 2/7 expressions in neurons and oligodendrocytes. On the other hand, BMP- 4 expressions were significantly decreased in astrocytes and oligodendrocytes around the lesion site. Together, our results reveal that Agm treatment improved neurological and histological outcomes, induced oligodendrogenesis, protected neurons, and decreased glial scar formation through modulating the BMP- 2/4/7 expressions following

  11. The Multifaceted Effects of Agmatine on Functional Recovery after Spinal Cord Injury through Modulations of BMP-2/4/7 Expressions in Neurons and Glial Cells

    Science.gov (United States)

    Park, Yu Mi; Lee, Won Taek; Bokara, Kiran Kumar; Seo, Su Kyoung; Park, Seung Hwa; Kim, Jae Hwan; Yenari, Midori A.; Park, Kyung Ah; Lee, Jong Eun

    2013-01-01

    Presently, few treatments for spinal cord injury (SCI) are available and none have facilitated neural regeneration and/or significant functional improvement. Agmatine (Agm), a guanidinium compound formed from decarboxylation of L-arginine by arginine decarboxylase, is a neurotransmitter/neuromodulator and been reported to exert neuroprotective effects in central nervous system injury models including SCI. The purpose of this study was to demonstrate the multifaceted effects of Agm on functional recovery and remyelinating events following SCI. Compression SCI in mice was produced by placing a 15 g/mm2 weight for 1 min at thoracic vertebra (Th) 9 segment. Mice that received an intraperitoneal (i.p.) injection of Agm (100 mg/kg/day) within 1 hour after SCI until 35 days showed improvement in locomotor recovery and bladder function. Emphasis was made on the analysis of remyelination events, neuronal cell preservation and ablation of glial scar area following SCI. Agm treatment significantly inhibited the demyelination events, neuronal loss and glial scar around the lesion site. In light of recent findings that expressions of bone morphogenetic proteins (BMPs) are modulated in the neuronal and glial cell population after SCI, we hypothesized whether Agm could modulate BMP- 2/4/7 expressions in neurons, astrocytes, oligodendrocytes and play key role in promoting the neuronal and glial cell survival in the injured spinal cord. The results from computer assisted stereological toolbox analysis (CAST) demonstrate that Agm treatment dramatically increased BMP- 2/7 expressions in neurons and oligodendrocytes. On the other hand, BMP- 4 expressions were significantly decreased in astrocytes and oligodendrocytes around the lesion site. Together, our results reveal that Agm treatment improved neurological and histological outcomes, induced oligodendrogenesis, protected neurons, and decreased glial scar formation through modulating the BMP- 2/4/7 expressions following SCI. PMID

  12. Estudio del quitosano como biomaterial portador de rhBMP-2: desarrollo, caracterización y aplicabilidad en regeneración de tejido óseo

    OpenAIRE

    Abarrategi López, Ander

    2008-01-01

    La ingeniería de tejidos es un campo de investigación emergente y profundamente multidisciplinar. En esencia, esta disciplina busca nuevas terapias que permitan obtener tejido vivo y funcional, mediante un soporte activo, células y factores diferenciadores. En este contexto, el objetivo de este trabajo es aportar propiedades osteoinductivas a materiales implantables de uso clínico. Puesto que la rhBMP-2 es el factor osteodiferenciador más conocido, ésta proteína se sintetizó en el laboratorio...

  13. Preparation and physical characterization of calcium sulfate cement/silica-based mesoporous material composites for controlled release of BMP-2

    Directory of Open Access Journals (Sweden)

    Tan H

    2015-07-01

    Full Text Available Honglue Tan,1 Shengbing Yang,2 Pengyi Dai,1 Wuyin Li,1 Bing Yue2 1Luoyang Orthopedics and Traumatology Institution, Luoyang Orthopedic-Traumatological Hospital, Luoyang, 2Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China Abstract: As a commonly used implant material, calcium sulfate cement (CSC, has some shortcomings, including low compressive strength, weak osteoinduction capability, and rapid degradation. In this study, silica-based mesoporous materials such as SBA-15 were synthesized and combined with CSC to prepare CSC/SBA-15 composites. The properties of SBA-15 were characterized by X-ray diffraction, transmission electron microscopy, and nitrogen adsorption–desorption isotherms. SBA-15 was blended into CSC at 0, 5, 10, and 20 wt%, referred to as CSC, CSC-5S (5% mass ratio, CSC-10S (10% mass ratio, and CSC-20S (20% mass ratio, respectively. Fourier-transform infrared spectroscopy and compression tests were used to determine the structure and mechanical properties of the composites, respectively. The formation of hydroxyapatite on composite surfaces was analyzed using scanning electron microscopy and X-ray diffraction after soaking in simulated body fluid. BMP-2 was loaded into the composites by vacuum freeze-drying, and its release characteristics were detected by Bradford protein assay. The in vitro degradation of the CSC/SBA-15 composite was investigated by measuring weight loss. The results showed that the orderly, nanostructured, mesoporous SBA-15 possessed regular pore size and structure. The compressive strength of CSC/SBA-15 increased with the increase in SBA-15 mass ratio, and CSC-20S demonstrated the maximum strength. Compared to CSC, hydroxyapatite that formed on the surfaces of CSC/SBA-15 was uniform and compact. The degradation rate of CSC/SBA-15 decreased with increasing

  14. Spatial control of bone formation using a porous polymer scaffold co-delivering anabolic rhBMP-2 and anti-resorptive agents

    Directory of Open Access Journals (Sweden)

    NYC Yu

    2014-01-01

    Full Text Available Current clinical delivery of recombinant human bone morphogenetic proteins (rhBMPs utilises freeze-dried collagen. Despite effective new bone generation, rhBMP via collagen can be limited by significant complications due to inflammation and uncontrolled bone formation. This study aimed to produce an alternative rhBMP local delivery system to permit more controllable and superior rhBMP-induced bone formation. Cylindrical porous poly(lactic-co-glycolic acid (PLGA scaffolds were manufactured by thermally-induced phase separation. Scaffolds were encapsulated with anabolic rhBMP-2 (20 µg ± anti-resorptive agents: zoledronic acid (5 µg ZA, ZA pre-adsorbed onto hydroxyapatite microparticles, (5 µg ZA/2 % HA or IkappaB kinase (IKK inhibitor (10 µg PS-1145. Scaffolds were inserted in a 6-mm critical-sized femoral defect in Wistar rats, and compared against rhBMP-2 via collagen. The regenerate region was examined at 6 weeks by 3D microCT and descriptive histology. MicroCT and histology revealed rhBMP-induced bone was more restricted in the PLGA scaffolds than collagen scaffolds (-92.3 % TV, p < 0.01. The regenerate formed by PLGA + rhBMP-2/ZA/HA showed comparable bone volume to rhBMP-2 via collagen, and bone mineral density was +9.1 % higher (p < 0.01. Local adjunct ZA/HA or PS-1145 significantly enhanced PLGA + rhBMP-induced bone formation by +78.2 % and +52.0 %, respectively (p ≤ 0.01. Mechanistically, MG-63 human osteoblast-like cells showed cellular invasion and proliferation within PLGA scaffolds. In conclusion, PLGA scaffolds enabled superior spatial control of rhBMP-induced bone formation over clinically-used collagen. The PLGA scaffold has the potential to avoid uncontrollable bone formation-related safety issues and to customise bone shape by scaffold design. Moreover, local treatment with anti-resorptive agents incorporated within the scaffold further augmented rhBMP-induced bone formation.

  15. A hairpin within YAP mRNA 3′UTR functions in regulation at post-transcription level

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yuen; Wang, Yuan; Feng, Jinyan; Feng, Guoxing; Zheng, Minying; Yang, Zhe; Xiao, Zelin; Lu, Zhanping [State Key Laboratory of Medicinal Chemical Biology, Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071 (China); Ye, Lihong [State Key Laboratory of Medicinal Chemical Biology, Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin 300071 (China); Zhang, Xiaodong, E-mail: zhangxd@nankai.edu.cn [State Key Laboratory of Medicinal Chemical Biology, Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071 (China)

    2015-04-03

    The central dogma of gene expression is that DNA is transcribed into messenger RNAs, which in turn serve as the template for protein synthesis. Recently, it has been reported that mRNAs display regulatory roles that rely on their ability to compete for microRNA binding, independent of their protein-coding function. However, the regulatory mechanism of mRNAs remains poorly understood. Here, we report that a hairpin within YAP mRNA 3′untranslated region (3′UTR) functions in regulation at post-transcription level through generating endogenous siRNAs (esiRNAs). Bioinformatics analysis for secondary structure showed that YAP mRNA displayed a hairpin structure (termed standard hairpin, S-hairpin) within its 3′UTR. Surprisingly, we observed that the overexpression of S-hairpin derived from YAP 3′UTR (YAP-sh) increased the luciferase reporter activities of transcriptional factor NF-κB and AP-1 in 293T cells. Moreover, we identified that a fragment from YAP-sh, an esiRNA, was able to target mRNA 3′UTR of NF2 (a member of Hippo-signaling pathway) and YAP mRNA 3′UTR itself in hepatoma cells. Thus, we conclude that the YAP-sh within YAP mRNA 3′UTR may serve as a novel regulatory element, which functions in regulation at post-transcription level. Our finding provides new insights into the mechanism of mRNAs in regulatory function. - Highlights: • An S-hairpin within YAP mRNA 3′UTR possesses regulatory function. • YAP-sh acts as a regulatory element for YAP at post-transcription level. • YAP-sh-3p20, an esiRNA derived from YAP-sh, targets mRNAs of YAP and NF2. • YAP-sh-3p20 depresses the proliferation of HepG2 cells in vitro.

  16. A hairpin within YAP mRNA 3′UTR functions in regulation at post-transcription level

    International Nuclear Information System (INIS)

    Gao, Yuen; Wang, Yuan; Feng, Jinyan; Feng, Guoxing; Zheng, Minying; Yang, Zhe; Xiao, Zelin; Lu, Zhanping; Ye, Lihong; Zhang, Xiaodong

    2015-01-01

    The central dogma of gene expression is that DNA is transcribed into messenger RNAs, which in turn serve as the template for protein synthesis. Recently, it has been reported that mRNAs display regulatory roles that rely on their ability to compete for microRNA binding, independent of their protein-coding function. However, the regulatory mechanism of mRNAs remains poorly understood. Here, we report that a hairpin within YAP mRNA 3′untranslated region (3′UTR) functions in regulation at post-transcription level through generating endogenous siRNAs (esiRNAs). Bioinformatics analysis for secondary structure showed that YAP mRNA displayed a hairpin structure (termed standard hairpin, S-hairpin) within its 3′UTR. Surprisingly, we observed that the overexpression of S-hairpin derived from YAP 3′UTR (YAP-sh) increased the luciferase reporter activities of transcriptional factor NF-κB and AP-1 in 293T cells. Moreover, we identified that a fragment from YAP-sh, an esiRNA, was able to target mRNA 3′UTR of NF2 (a member of Hippo-signaling pathway) and YAP mRNA 3′UTR itself in hepatoma cells. Thus, we conclude that the YAP-sh within YAP mRNA 3′UTR may serve as a novel regulatory element, which functions in regulation at post-transcription level. Our finding provides new insights into the mechanism of mRNAs in regulatory function. - Highlights: • An S-hairpin within YAP mRNA 3′UTR possesses regulatory function. • YAP-sh acts as a regulatory element for YAP at post-transcription level. • YAP-sh-3p20, an esiRNA derived from YAP-sh, targets mRNAs of YAP and NF2. • YAP-sh-3p20 depresses the proliferation of HepG2 cells in vitro

  17. Insulin-like growth factor-1 (IGF-1) enhances the osteogenic activity of bone morphogenetic protein-6 (BMP-6) in vitro and in vivo, and together have a stronger osteogenic effect than when IGF-1 is combined with BMP-2.

    Science.gov (United States)

    Rico-Llanos, Gustavo A; Becerra, Jose; Visser, Rick

    2017-07-01

    Bone morphogenetic protein-2 (BMP-2) is widely used in orthopedic surgery and bone tissue engineering because of its strong osteogenic activity. However, BMP-2 treatments have several drawbacks and many groups are actively exploring alternatives. Since BMP-6 has been demonstrated to be more osteoinductive, its use, either alone or together with other growth factors, might be an interesting option. In this work, we have compared the effect of BMP-2, BMP-6, or insulin-like growth factor-1 (IGF-1), either alone or in combination. Murine preosteoblasts were treated with 15 nM IGF-1 and/or 6 nM BMP-2 or -6 and the expression of osteogenic marker genes, proliferation, and alkaline phosphatase (ALP) activity in vitro were analyzed. The results showed that IGF-1 greatly enhanced the BMP-induced osteogenic differentiation of these cells in general and that the ALP activity in the cultures was higher when the combination was made with BMP-6 than with BMP-2. Furthermore, we tested the osteogenic potential of these treatments in vivo by loading 25 pmoles of IGF-1 and/or 10 pmoles of BMP-2 or -6 onto absorbable collagen sponges and implanting them into an ectopic bone formation model in rats. This study revealed that only BMP-6 was able to induce bone formation at the used dose and that the addition of IGF-1 contributed to an increase of the mineralization in the implants. Hence, the combination of BMP-6 with IGF-1 might be a better alternative than BMP-2 for orthopedic surgery or bone tissue engineering approaches. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1867-1875, 2017. © 2017 Wiley Periodicals, Inc.

  18. Salinity inhibits post transcriptional processing of chloroplast 16S rRNA in shoot cultures of jojoba (Simmondsia chinesis).

    Science.gov (United States)

    Mizrahi-Aviv, Ela; Mills, David; Benzioni, Aliza; Bar-Zvi, Dudy

    2005-03-01

    Chloroplast metabolism is rapidly affected by salt stress. Photosynthesis is one of the first processes known to be affected by salinity. Here, we report that salinity inhibits chloroplast post-transcriptional RNA processing. A differentially expressed 680-bp cDNA, containing the 3' sequence of 16S rRNA, transcribed intergenic spacer, exon 1 and intron of tRNA(Ile), was isolated by differential display reverse transcriptase PCR from salt-grown jojoba (Simmondsia chinesis) shoot cultures. Northern blot analysis indicated that although most rRNA appears to be fully processed, partially processed chloroplast 16S rRNA accumulates in salt-grown cultures. Thus, salinity appears to decrease the processing of the rrn transcript. The possible effect of this decreased processing on physiological processes is, as yet, unknown.

  19. 1,25-Dihydroxyvitamin D3 inhibits cytokine production by human blood monocytes at the post-transcriptional level

    DEFF Research Database (Denmark)

    Müller, K; Haahr, P M; Diamant, M

    1992-01-01

    was not caused by impaired production of mRNA. Taken together, the study demonstrates a vitamin D-induced inhibitory effect of LPS-driven monokine production, which is most likely a vitamin D-receptor mediated phenomenon exerted at a post-transcriptional, presecretory level. Impaired monokine production may...... be of importance in 1,25-(OH)2D3-mediated inhibition of lymphocyte functions in vitro.......1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] inhibits lymphocyte proliferation and production of antibodies and lymphokines such as interleukin (IL)-2 and interferon gamma. These lymphocyte functions are dependent upon cytokines, including IL-1 alpha, IL-1 beta, IL-6 and tumour necrosis factor alpha...

  20. Continuity resection of the mandible after ameloblastoma - feasibility of oral rehabilitation with rhBMP-2 associated to bovine xenograft followed by implant installation.

    Science.gov (United States)

    Lustosa, Romulo Maciel; Macedo, Diogo de Vasconcelos; Iwaki, Lilian Cristina Vessoni; Tolentino, Elen de Souza; Hasse, Paulo Norberto; Marson, Giordano Bruno de Oliveira; Iwaki Filho, Liogi

    2015-10-01

    Recombinant human morphogenetic protein (rhBMP) is a graft alternative for extensive mandibular reconstruction after tumor resections. However, the feasibility of rhBMP-2 to receive osseointegrated implants and prosthetic rehabilitation has been rarely reported. This study reports on a case of an extensive solid ameloblastoma along the mandibular body. The treatment consisted of resection followed by off-label use of rhBMP type 2 associated with bovine bone xenograft. Eleven months postoperatively, the patient was prosthetically rehabilitated with dental implants, without evidence of resorption or complications. The literature on mandibular reconstructions using rhBMP and their feasibility for future osseointegrated implant placement was also reviewed. Based on the presented case, the association between rhBMP-2 and a bovine bone xenograft could be considered a feasible option for the reconstruction and rehabilitation of large mandibular defects after tumor resection. According to the literature, the use of rhBMP as a graft material is encouraging, with good clinical outcome. However, there are no long-term studies demonstrating success and survival rates of implants placed in these grafts. Future investigations will be required to ascertain the long-term survival of implants in areas grafted with rhBMP. Also, there is a lack of information regarding the prosthetic rehabilitation of these patients. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  1. Bone morphogenetic protein-2 (BMP-2 and transforming growth factor-β1 (TGF-β1 alter connexin 43 phosphorylation in MC3T3-E1 Cells

    Directory of Open Access Journals (Sweden)

    Rudkin George H

    2001-07-01

    Full Text Available Abstract Background Bone morphogenetic proteins (BMPs and transforming growth factor-βs (TGF-βs are important regulators of bone repair and regeneration. BMP-2 and TGF-β1 have been shown to inhibit gap junctional intercellular communication (GJIC in MC3T3-E1 cells. Connexin 43 (Cx43 has been shown to mediate GJIC in osteoblasts and it is the predominant gap junctional protein expressed in these murine osteoblast-like cells. We examined the expression, phosphorylation, and subcellular localization of Cx43 after treatment with BMP-2 or TGF-β1 to investigate a possible mechanism for the inhibition of GJIC. Results Northern blot analysis revealed no detectable change in the expression of Cx43 mRNA. Western blot analysis demonstrated no significant change in the expression of total Cx43 protein. However, significantly higher ratios of unphosphorylated vs. phosphorylated forms of Cx43 were detected after BMP-2 or TGF-β1 treatment. Immunofluorescence and cell protein fractionation revealed no detectable change in the localization of Cx43 between the cytosol and plasma membrane. Conclusions BMP-2 and TGF-β1 do not alter expression of Cx43 at the mRNA or protein level. BMP-2 and TGF-β1 may inhibit GJIC by decreasing the phosphorylated form of Cx43 in MC3T3-E1 cells.

  2. Neurotrophin-3 Induces BMP-2 and VEGF Activities and Promotes the Bony Repair of Injured Growth Plate Cartilage and Bone in Rats.

    Science.gov (United States)

    Su, Yu-Wen; Chung, Rosa; Ruan, Chun-Sheng; Chim, Shek Man; Kuek, Vincent; Dwivedi, Prem P; Hassanshahi, Mohammadhossein; Chen, Ke-Ming; Xie, Yangli; Chen, Lin; Foster, Bruce K; Rosen, Vicki; Zhou, Xin-Fu; Xu, Jiake; Xian, Cory J

    2016-06-01

    Injured growth plate is often repaired by bony tissue causing bone growth defects, for which the mechanisms remain unclear. Because neurotrophins have been implicated in bone fracture repair, here we investigated their potential roles in growth plate bony repair in rats. After a drill-hole injury was made in the tibial growth plate and bone, increased injury site mRNA expression was observed for neurotrophins NGF, BDNF, NT-3, and NT-4 and their Trk receptors. NT-3 and its receptor TrkC showed the highest induction. NT-3 was localized to repairing cells, whereas TrkC was observed in stromal cells, osteoblasts, and blood vessel cells at the injury site. Moreover, systemic NT-3 immunoneutralization reduced bone volume at injury sites and also reduced vascularization at the injured growth plate, whereas recombinant NT-3 treatment promoted bony repair with elevated levels of mRNA for osteogenic markers and bone morphogenetic protein (BMP-2) and increased vascularization and mRNA for vascular endothelial growth factor (VEGF) and endothelial cell marker CD31 at the injured growth plate. When examined in vitro, NT-3 promoted osteogenesis in rat bone marrow stromal cells, induced Erk1/2 and Akt phosphorylation, and enhanced expression of BMPs (particularly BMP-2) and VEGF in the mineralizing cells. It also induced CD31 and VEGF mRNA in rat primary endothelial cell culture. BMP activity appears critical for NT-3 osteogenic effect in vitro because it can be almost completely abrogated by co-addition of the BMP inhibitor noggin. Consistent with its angiogenic effect in vivo, NT-3 promoted angiogenesis in metatarsal bone explants, an effect abolished by co-treatment with anti-VEGF. This study suggests that NT-3 may be an osteogenic and angiogenic factor upstream of BMP-2 and VEGF in bony repair, and further studies are required to investigate whether NT-3 may be a potential target for preventing growth plate faulty bony repair or for promoting bone fracture healing. © 2016

  3. The STAR protein QKI-7 recruits PAPD4 to regulate post-transcriptional polyadenylation of target mRNAs.

    Science.gov (United States)

    Yamagishi, Ryota; Tsusaka, Takeshi; Mitsunaga, Hiroko; Maehata, Takaharu; Hoshino, Shin-ichi

    2016-04-07

    Emerging evidence has demonstrated that regulating the length of the poly(A) tail on an mRNA is an efficient means of controlling gene expression at the post-transcriptional level. In early development, transcription is silenced and gene expression is primarily regulated by cytoplasmic polyadenylation. In somatic cells, considerable progress has been made toward understanding the mechanisms of negative regulation by deadenylation. However, positive regulation through elongation of the poly(A) tail has not been widely studied due to the difficulty in distinguishing whether any observed increase in length is due to the synthesis of new mRNA, reduced deadenylation or cytoplasmic polyadenylation. Here, we overcame this barrier by developing a method for transcriptional pulse-chase analysis under conditions where deadenylases are suppressed. This strategy was used to show that a member of the Star family of RNA binding proteins, QKI, promotes polyadenylation when tethered to a reporter mRNA. Although multiple RNA binding proteins have been implicated in cytoplasmic polyadenylation during early development, previously only CPEB was known to function in this capacity in somatic cells. Importantly, we show that only the cytoplasmic isoform QKI-7 promotes poly(A) tail extension, and that it does so by recruiting the non-canonical poly(A) polymerase PAPD4 through its unique carboxyl-terminal region. We further show that QKI-7 specifically promotes polyadenylation and translation of three natural target mRNAs (hnRNPA1, p27(kip1)and β-catenin) in a manner that is dependent on the QKI response element. An anti-mitogenic signal that induces cell cycle arrest at G1 phase elicits polyadenylation and translation of p27(kip1)mRNA via QKI and PAPD4. Taken together, our findings provide significant new insight into a general mechanism for positive regulation of gene expression by post-transcriptional polyadenylation in somatic cells. © The Author(s) 2016. Published by Oxford

  4. The Anopheles gambiae cE5, a tight- and fast-binding thrombin inhibitor with post-transcriptionally regulated salivary-restricted expression

    Czech Academy of Sciences Publication Activity Database

    Ronca, R.; Kotsyfakis, Michalis; Lombardo, F.; Rizzo, C.; Currà, C.; Ponzi, M.; Fiorentino, G.; Ribeiro, J.M.C.; Arcà, B.

    2012-01-01

    Roč. 42, č. 9 (2012), s. 610-620 ISSN 0965-1748 R&D Projects: GA ČR GAP502/12/2409 Institutional research plan: CEZ:AV0Z60220518 Keywords : Anopheles * Salivary protein * Anti-thrombin * Anophelin * Hematophagy * Post-transcriptional regulation Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.234, year: 2012

  5. Development and Assessment of a 3D-Printed Scaffold with rhBMP-2 for an Implant Surgical Guide Stent and Bone Graft Material: A Pilot Animal Study

    OpenAIRE

    Bae, Ji Cheol; Lee, Jin-Ju; Shim, Jin-Hyung; Park, Keun-Ho; Lee, Jeong-Seok; Bae, Eun-Bin; Choi, Jae-Won; Huh, Jung-Bo

    2017-01-01

    In this study, a new concept of a 3D-printed scaffold was introduced for the accurate placement of an implant and the application of a recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded bone graft. This preliminary study was conducted using two adult beagles to evaluate the 3D-printed polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP)/bone decellularized extracellular matrix (bdECM) scaffold conjugated with rhBMP-2 for the simultaneous use as an implant surgical guide stent an...

  6. Post-Transcriptional Regulation Prevents Accumulation of Glutathione Reductase Protein and Activity in the Bundle Sheath Cells of Maize1

    Science.gov (United States)

    Pastori, Gabriela M.; Mullineaux, Philip M.; Foyer, Christine H.

    2000-01-01

    Glutathione reductase (GR; EC 1.6.4.2) activity was assayed in bundle sheath and mesophyll cells of maize (Zea mays L. var H99) from plants grown at 20°C, 18°C, and 15°C. The purity of each fraction was determined by measuring the associated activity of the compartment-specific marker enzymes, Rubisco and phosphoenolpyruvate carboxylase, respectively. GR activity and the abundance of GR protein and mRNA increased in plants grown at 15°C and 18°C compared with those grown at 20°C. In all cases GR activity was found only in mesophyll fractions of the leaves, with no GR activity being detectable in bundle sheath extracts. Immunogold labeling with GR-specific antibodies showed that the GR protein was exclusively localized in the mesophyll cells of leaves at all growth temperatures, whereas GR transcripts (as determined by in situ hybridization techniques) were observed in both cell types. These results indicate that post-transcriptional regulation prevents GR accumulation in the bundle sheath cells of maize leaves. The resulting limitation on the capacity for regeneration of reduced glutathione in this compartment may contribute to the extreme chilling sensitivity of maize leaves. PMID:10712529

  7. Dissecting the expression relationships between RNA-binding proteins and their cognate targets in eukaryotic post-transcriptional regulatory networks

    Science.gov (United States)

    Nishtala, Sneha; Neelamraju, Yaseswini; Janga, Sarath Chandra

    2016-05-01

    RNA-binding proteins (RBPs) are pivotal in orchestrating several steps in the metabolism of RNA in eukaryotes thereby controlling an extensive network of RBP-RNA interactions. Here, we employed CLIP (cross-linking immunoprecipitation)-seq datasets for 60 human RBPs and RIP-ChIP (RNP immunoprecipitation-microarray) data for 69 yeast RBPs to construct a network of genome-wide RBP- target RNA interactions for each RBP. We show in humans that majority (~78%) of the RBPs are strongly associated with their target transcripts at transcript level while ~95% of the studied RBPs were also found to be strongly associated with expression levels of target transcripts when protein expression levels of RBPs were employed. At transcript level, RBP - RNA interaction data for the yeast genome, exhibited a strong association for 63% of the RBPs, confirming the association to be conserved across large phylogenetic distances. Analysis to uncover the features contributing to these associations revealed the number of target transcripts and length of the selected protein-coding transcript of an RBP at the transcript level while intensity of the CLIP signal, number of RNA-Binding domains, location of the binding site on the transcript, to be significant at the protein level. Our analysis will contribute to improved modelling and prediction of post-transcriptional networks.

  8. Bypass of cell cycle arrest induced by transient DNMT1 post-transcriptional silencing triggers aneuploidy in human cells

    Directory of Open Access Journals (Sweden)

    Barra Viviana

    2012-02-01

    Full Text Available Abstract Background Aneuploidy has been acknowledged as a major source of genomic instability in cancer, and it is often considered the result of chromosome segregation errors including those caused by defects in genes controlling the mitotic spindle assembly, centrosome duplication and cell-cycle checkpoints. Aneuploidy and chromosomal instability has been also correlated with epigenetic alteration, however the molecular basis of this correlation is poorly understood. Results To address the functional connection existing between epigenetic changes and aneuploidy, we used RNA-interference to silence the DNMT1 gene, encoding for a highly conserved member of the DNA methyl-transferases. DNMT1 depletion slowed down proliferation of near-diploid human tumor cells (HCT116 and triggered G1 arrest in primary human fibroblasts (IMR90, by inducing p53 stabilization and, in turn, p21waf1 transactivation. Remarkably, p53 increase was not caused by DNA damage and was not observed after p14-ARF post-transcriptional silencing. Interestingly, DNMT1 silenced cells with p53 or p14-ARF depleted did not arrest in G1 but, instead, underwent DNA hypomethylation and became aneuploid. Conclusion Our results suggest that DNMT1 depletion triggers a p14ARF/p53 dependent cell cycle arrest to counteract the aneuploidy induced by changes in DNA methylation.

  9. Multiple common susceptibility variants near BMP pathway loci GREM1, BMP4, and BMP2 explain part of the missing heritability of colorectal cancer.

    Directory of Open Access Journals (Sweden)

    Ian P M Tomlinson

    2011-06-01

    Full Text Available Genome-wide association studies (GWAS have identified 14 tagging single nucleotide polymorphisms (tagSNPs that are associated with the risk of colorectal cancer (CRC, and several of these tagSNPs are near bone morphogenetic protein (BMP pathway loci. The penalty of multiple testing implicit in GWAS increases the attraction of complementary approaches for disease gene discovery, including candidate gene- or pathway-based analyses. The strongest candidate loci for additional predisposition SNPs are arguably those already known both to have functional relevance and to be involved in disease risk. To investigate this proposition, we searched for novel CRC susceptibility variants close to the BMP pathway genes GREM1 (15q13.3, BMP4 (14q22.2, and BMP2 (20p12.3 using sample sets totalling 24,910 CRC cases and 26,275 controls. We identified new, independent CRC predisposition SNPs close to BMP4 (rs1957636, P = 3.93×10(-10 and BMP2 (rs4813802, P = 4.65×10(-11. Near GREM1, we found using fine-mapping that the previously-identified association between tagSNP rs4779584 and CRC actually resulted from two independent signals represented by rs16969681 (P = 5.33×10(-8 and rs11632715 (P = 2.30×10(-10. As low-penetrance predisposition variants become harder to identify-owing to small effect sizes and/or low risk allele frequencies-approaches based on informed candidate gene selection may become increasingly attractive. Our data emphasise that genetic fine-mapping studies can deconvolute associations that have arisen owing to independent correlation of a tagSNP with more than one functional SNP, thus explaining some of the apparently missing heritability of common diseases.

  10. Characteristics and stimulation potential with BMP-2 and BMP-7 of tenocyte-like cells isolated from the rotator cuff of female donors.

    Directory of Open Access Journals (Sweden)

    Franka Klatte-Schulz

    Full Text Available Tendon bone healing of the rotator cuff is often associated with non-healing or recurrent defects, which seems to be influenced by the patient's age and sex. The present study aims to examine cellular biological characteristics of tenocyte-like cells that may contribute to this impaired rotator cuff healing. Moreover, a therapeutic approach using growth factors could possibly stimulate tendon bone healing. Therefore, our second aim was to identify patient groups who would particularly benefit from growth factor stimulation. Tenocyte-like cells isolated from supraspinatus tendons of female donors younger and older than 65 years of age were characterized with respect to different cellular biological parameters, such as cell density, cell count, marker expression, collagen-I protein synthesis, and stem cell potential. Furthermore, cells of the donor groups were stimulated with BMP-2 and BMP-7 (200 and 1000 ng/ml in 3D-culture and analyzed for cell count, marker expression and collagen-I protein synthesis. Female donors older than 65 years of age showed significantly decreased cell count and collagen-I protein synthesis compared to cells from donors younger than 65 years. Cellular biological parameters including cell count, collagen-I and -III expression, and collagen-I protein synthesis of cells from both donor groups were stimulated with BMP-2 and BMP-7. The cells from donors older than 65 years revealed a decreased stimulation potential for cell count compared to the younger group. Cells from female donors older than 65 years of age showed inferior cellular biological characteristics. This may be one reason for a weaker healing potential observed in older female patients and should be taken into consideration for tendon bone healing of the rotator cuff.

  11. Ancestral regulatory circuits governing ectoderm patterning downstream of Nodal and BMP2/4 revealed by gene regulatory network analysis in an echinoderm.

    Directory of Open Access Journals (Sweden)

    Alexandra Saudemont

    2010-12-01

    Full Text Available Echinoderms, which are phylogenetically related to vertebrates and produce large numbers of transparent embryos that can be experimentally manipulated, offer many advantages for the analysis of the gene regulatory networks (GRN regulating germ layer formation. During development of the sea urchin embryo, the ectoderm is the source of signals that pattern all three germ layers along the dorsal-ventral axis. How this signaling center controls patterning and morphogenesis of the embryo is not understood. Here, we report a large-scale analysis of the GRN deployed in response to the activity of this signaling center in the embryos of the Mediterranean sea urchin Paracentrotus lividus, in which studies with high spatial resolution are possible. By using a combination of in situ hybridization screening, overexpression of mRNA, recombinant ligand treatments, and morpholino-based loss-of-function studies, we identified a cohort of transcription factors and signaling molecules expressed in the ventral ectoderm, dorsal ectoderm, and interposed neurogenic ("ciliary band" region in response to the known key signaling molecules Nodal and BMP2/4 and defined the epistatic relationships between the most important genes. The resultant GRN showed a number of striking features. First, Nodal was found to be essential for the expression of all ventral and dorsal marker genes, and BMP2/4 for all dorsal genes. Second, goosecoid was identified as a central player in a regulatory sub-circuit controlling mouth formation, while tbx2/3 emerged as a critical factor for differentiation of the dorsal ectoderm. Finally, and unexpectedly, a neurogenic ectoderm regulatory circuit characterized by expression of "ciliary band" genes was triggered in the absence of TGF beta signaling. We propose a novel model for ectoderm regionalization, in which neural ectoderm is the default fate in the absence of TGF beta signaling, and suggest that the stomodeal and neural subcircuits that we

  12. Development and Assessment of a 3D-Printed Scaffold with rhBMP-2 for an Implant Surgical Guide Stent and Bone Graft Material: A Pilot Animal Study

    Directory of Open Access Journals (Sweden)

    Ji Cheol Bae

    2017-12-01

    Full Text Available In this study, a new concept of a 3D-printed scaffold was introduced for the accurate placement of an implant and the application of a recombinant human bone morphogenetic protein-2 (rhBMP-2-loaded bone graft. This preliminary study was conducted using two adult beagles to evaluate the 3D-printed polycaprolactone (PCL/β-tricalcium phosphate (β-TCP/bone decellularized extracellular matrix (bdECM scaffold conjugated with rhBMP-2 for the simultaneous use as an implant surgical guide stent and bone graft material that promotes new bone growth. Teeth were extracted from the mandible of the beagle model and scanned by computed tomography (CT to fabricate a customized scaffold that would fit the bone defect. After positioning the implant guide scaffold, the implant was placed and rhBMP-2 was injected into the scaffold of the experimental group. The two beagles were sacrificed after three months. The specimen block was obtained and scanned by micro-CT. Histological analysis showed that the control and experimental groups had similar new bone volume (NBV, % but the experimental group with BMP exhibited a significantly higher bone-to-implant contact ratio (BIC, %. Within the limitations of this preliminary study, a 3D-printed scaffold conjugated with rhBMP-2 can be used simultaneously as an implant surgical guide and a bone graft in a large bone defect site. Further large-scale studies will be needed to confirm these results.

  13. Development and Assessment of a 3D-Printed Scaffold with rhBMP-2 for an Implant Surgical Guide Stent and Bone Graft Material: A Pilot Animal Study

    Science.gov (United States)

    Bae, Ji Cheol; Lee, Jin-Ju; Shim, Jin-Hyung; Park, Keun-Ho; Lee, Jeong-Seok; Bae, Eun-Bin; Choi, Jae-Won; Huh, Jung-Bo

    2017-01-01

    In this study, a new concept of a 3D-printed scaffold was introduced for the accurate placement of an implant and the application of a recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded bone graft. This preliminary study was conducted using two adult beagles to evaluate the 3D-printed polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP)/bone decellularized extracellular matrix (bdECM) scaffold conjugated with rhBMP-2 for the simultaneous use as an implant surgical guide stent and bone graft material that promotes new bone growth. Teeth were extracted from the mandible of the beagle model and scanned by computed tomography (CT) to fabricate a customized scaffold that would fit the bone defect. After positioning the implant guide scaffold, the implant was placed and rhBMP-2 was injected into the scaffold of the experimental group. The two beagles were sacrificed after three months. The specimen block was obtained and scanned by micro-CT. Histological analysis showed that the control and experimental groups had similar new bone volume (NBV, %) but the experimental group with BMP exhibited a significantly higher bone-to-implant contact ratio (BIC, %). Within the limitations of this preliminary study, a 3D-printed scaffold conjugated with rhBMP-2 can be used simultaneously as an implant surgical guide and a bone graft in a large bone defect site. Further large-scale studies will be needed to confirm these results. PMID:29258172

  14. Optimisation of transgene action at the post-transcriptional level: high quality parthenocarpic fruits in industrial tomatoes

    Directory of Open Access Journals (Sweden)

    Defez Roberto

    2002-01-01

    Full Text Available Abstract Background Genetic engineering of parthenocarpy confers to horticultural plants the ability to produce fruits under environmental conditions that curtail fruit productivity and quality. The DefH9-iaaM transgene, whose predicted action is to confer auxin synthesis specifically in the placenta, ovules and derived tissues, has been shown to confer parthenocarpy to several plant species (tobacco, eggplant, tomato and varieties. Results UC82 tomato plants, a typical cultivar used by the processing industry, transgenic for the DefH9-iaaM gene produce parthenocarpic fruits that are malformed. UC82 plants transgenic for the DefH9-RI-iaaM, a DefH9-iaaM derivative gene modified in its 5'ULR by replacing 53 nucleotides immediately upstream of the AUG initiation codon with an 87 nucleotides-long sequence derived from the rolA intron sequence, produce parthenocarpic fruits of high quality. In an in vitro translation system, the iaaM mRNA, modified in its 5'ULR is translated 3–4 times less efficiently than the original transcript. An optimal expressivity of parthenocarpy correlates with a reduced transgene mRNA steady state level in DefH9-RI-iaaM flower buds in comparison to DefH9-iaaM flower buds. Consistent with the known function of the iaaM gene, flower buds transgenic for the DefH9-RI-iaaM gene contain ten times more IAA than control untransformed flower buds, but five times less than DefH9-iaaM flower buds. Conclusions By using an auxin biosynthesis transgene downregulated at the post-transcriptional level, an optimal expressivity of parthenocarpy has been achieved in a genetic background not suitable for the original transgene. Thus, the method allows the generation of a wider range of expressivity of the desired trait in transgenic plants.

  15. Resveratrol post-transcriptionally regulates pro-inflammatory gene expression via regulation of KSRP RNA binding activity

    Science.gov (United States)

    Bollmann, Franziska; Art, Julia; Henke, Jenny; Schrick, Katharina; Besche, Verena; Bros, Matthias; Li, Huige; Siuda, Daniel; Handler, Norbert; Bauer, Florian; Erker, Thomas; Behnke, Felix; Mönch, Bettina; Härdle, Lorena; Hoffmann, Markus; Chen, Ching-Yi; Förstermann, Ulrich; Dirsch, Verena M.; Werz, Oliver; Kleinert, Hartmut; Pautz, Andrea

    2014-01-01

    Resveratrol shows beneficial effects in inflammation-based diseases like cancer, cardiovascular and chronic inflammatory diseases. Therefore, the molecular mechanisms of the anti-inflammatory resveratrol effects deserve more attention. In human epithelial DLD-1 and monocytic Mono Mac 6 cells resveratrol decreased the expression of iNOS, IL-8 and TNF-α by reducing mRNA stability without inhibition of the promoter activity. Shown by pharmacological and siRNA-mediated inhibition, the observed effects are SIRT1-independent. Target-fishing and drug responsive target stability experiments showed selective binding of resveratrol to the RNA-binding protein KSRP, a central post-transcriptional regulator of pro-inflammatory gene expression. Knockdown of KSRP expression prevented resveratrol-induced mRNA destabilization in human and murine cells. Resveratrol did not change KSRP expression, but immunoprecipitation experiments indicated that resveratrol reduces the p38 MAPK-related inhibitory KSRP threonine phosphorylation, without blocking p38 MAPK activation or activity. Mutation of the p38 MAPK target site in KSRP blocked the resveratrol effect on pro-inflammatory gene expression. In addition, resveratrol incubation enhanced KSRP-exosome interaction, which is important for mRNA degradation. Finally, resveratrol incubation enhanced its intra-cellular binding to the IL-8, iNOS and TNF-α mRNA. Therefore, modulation of KSRP mRNA binding activity and, thereby, enhancement of mRNA degradation seems to be the common denominator of many anti-inflammatory effects of resveratrol. PMID:25352548

  16. Post-transcriptional generation of miRNA variants by multiple nucleotidyl transferases contributes to miRNA transcriptome complexity.

    Science.gov (United States)

    Wyman, Stacia K; Knouf, Emily C; Parkin, Rachael K; Fritz, Brian R; Lin, Daniel W; Dennis, Lucas M; Krouse, Michael A; Webster, Philippa J; Tewari, Muneesh

    2011-09-01

    Modification of microRNA sequences by the 3' addition of nucleotides to generate so-called "isomiRs" adds to the complexity of miRNA function, with recent reports showing that 3' modifications can influence miRNA stability and efficiency of target repression. Here, we show that the 3' modification of miRNAs is a physiological and common post-transcriptional event that shows selectivity for specific miRNAs and is observed across species ranging from C. elegans to human. The modifications result predominantly from adenylation and uridylation and are seen across tissue types, disease states, and developmental stages. To quantitatively profile 3' nucleotide additions, we developed and validated a novel assay based on NanoString Technologies' nCounter platform. For certain miRNAs, the frequency of modification was altered by processes such as cell differentiation, indicating that 3' modification is a biologically regulated process. To investigate the mechanism of 3' nucleotide additions, we used RNA interference to screen a panel of eight candidate miRNA nucleotidyl transferases for 3' miRNA modification activity in human cells. Multiple enzymes, including MTPAP, PAPD4, PAPD5, ZCCHC6, ZCCHC11, and TUT1, were found to govern 3' nucleotide addition to miRNAs in a miRNA-specific manner. Three of these enzymes-MTPAP, ZCCHC6, and TUT1-have not previously been known to modify miRNAs. Collectively, our results indicate that 3' modification observed in next-generation small RNA sequencing data is a biologically relevant process, and identify enzymatic mechanisms that may lead to new approaches for modulating miRNA activity in vivo.

  17. Genome-wide mRNA processing in methanogenic archaea reveals post-transcriptional regulation of ribosomal protein synthesis.

    Science.gov (United States)

    Qi, Lei; Yue, Lei; Feng, Deqin; Qi, Fengxia; Li, Jie; Dong, Xiuzhu

    2017-07-07

    Unlike stable RNAs that require processing for maturation, prokaryotic cellular mRNAs generally follow an 'all-or-none' pattern. Herein, we used a 5΄ monophosphate transcript sequencing (5΄P-seq) that specifically captured the 5΄-end of processed transcripts and mapped the genome-wide RNA processing sites (PSSs) in a methanogenic archaeon. Following statistical analysis and stringent filtration, we identified 1429 PSSs, among which 23.5% and 5.4% were located in 5΄ untranslated region (uPSS) and intergenic region (iPSS), respectively. A predominant uridine downstream PSSs served as a processing signature. Remarkably, 5΄P-seq detected overrepresented uPSS and iPSS in the polycistronic operons encoding ribosomal proteins, and the majority upstream and proximal ribosome binding sites, suggesting a regulatory role of processing on translation initiation. The processed transcripts showed increased stability and translation efficiency. Particularly, processing within the tricistronic transcript of rplA-rplJ-rplL enhanced the translation of rplL, which can provide a driving force for the 1:4 stoichiometry of L10 to L12 in the ribosome. Growth-associated mRNA processing intensities were also correlated with the cellular ribosomal protein levels, thereby suggesting that mRNA processing is involved in tuning growth-dependent ribosome synthesis. In conclusion, our findings suggest that mRNA processing-mediated post-transcriptional regulation is a potential mechanism of ribosomal protein synthesis and stoichiometry. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  18. Neural expression and post-transcriptional dosage compensation of the steroid metabolic enzyme 17β-HSD type 4

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    Wise Petra M

    2010-04-01

    Full Text Available Abstract Background Steroids affect many tissues, including the brain. In the zebra finch, the estrogenic steroid estradiol (E2 is especially effective at promoting growth of the neural circuit specialized for song. In this species, only the males sing and they have a much larger and more interconnected song circuit than females. Thus, it was surprising that the gene for 17β-hydroxysteroid dehydrogenase type 4 (HSD17B4, an enzyme that converts E2 to a less potent estrogen, had been mapped to the Z sex chromosome. As a consequence, it was likely that HSD17B4 was differentially expressed in males (ZZ and females (ZW because dosage compensation of Z chromosome genes is incomplete in birds. If a higher abundance of HSD17B4 mRNA in males than females was translated into functional enzyme in the brain, then contrary to expectation, males could produce less E2 in their brains than females. Results Here, we used molecular and biochemical techniques to confirm the HSD17B4 Z chromosome location in the zebra finch and to determine that HSD17B4 mRNA and activity were detectable in the early developing and adult brain. As expected, HSD17B4 mRNA expression levels were higher in males compared to females. This provides further evidence of the incomplete Z chromosome inactivation mechanisms in birds. We detected HSD17B4 mRNA in regions that suggested a role for this enzyme in the early organization and adult function of song nuclei. We did not, however, detect significant sex differences in HSD17B4 activity levels in the adult brain. Conclusions Our results demonstrate that the HSD17B4 gene is expressed and active in the zebra finch brain as an E2 metabolizing enzyme, but that dosage compensation of this Z-linked gene may occur via post-transcriptional mechanisms.

  19. Post-transcriptional silencing of flavonol synthase mRNA in tobacco leads to fruits with arrested seed set.

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    Monika Mahajan

    Full Text Available Flavonoids are synthesized by phenylpropanoid pathway. They are known to participate in large number of physiological and biochemical processes in plants. Parthenocarpy and male sterility has earlier been reported by silencing chalcone synthase (CHS encoding gene. Silencing of CHS has blocked the synthesis of most of useful flavonoids including flavan-3-ols and flavonols. Also, these studies could not identify whether parthenocarpy/male sterility were due to lack of flavan-3-ols or flavonols or both. Flavonol synthase (FLS is an important enzyme of flavonoid pathway that catalyzes the formation of flavonols. In this article, we propose a novel strategy towards the generation of seedless or less-seeded fruits by downregulation of flavonol biosynthesis in tobacco (Nicotiana tabacum cv Xanthi through post-transcriptional gene silencing (PTGS of FLS encoding mRNA. The FLS silenced lines were observed for 20-80% reduction in FLS encoding gene expression and 25-93% reduction in flavonol (quercetin content. Interestingly, these FLS silenced tobacco lines also showed reduction in their anthocyanidins content. While the content of flavan-3-ols (catechin, epi-catechin and epi-gallocatechin was found to be increased in FLS silenced lines. The delayed flowering in FLS silenced lines could be due to decrease in level of indole acetic acid (IAA at apical region of their shoots. Furthermore, the pollen germination was hampered and pollens were unable to produce functional pollen tube in FLS silenced tobacco lines. Pods of FLS silenced lines contained significantly less number of seeds. The in vitro and in vivo studies where 1 µM quercetin was supplied to germination media, documented the restoration of normal pollen germination and pollen tube growth. This finding identified the role of flavonols particularly quercetin in pollen germination as well as in the regulation of plant fertility. Results also suggest a novel approach towards generation of seedless

  20. Caveolin-1-mediated post-transcriptional regulation of inducible nitric oxide synthase in human colon carcinoma cells

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    EMANUELA FELLEY-BOSCO

    2002-01-01

    Full Text Available Reactive oxygen species are now widely recognized as important players contributing both to cell homeostasis and the development of disease. In this respect nitric oxide (NO is no exception. The discussion here will center on regulation of the inducible form of nitric oxide synthase (iNOS for two reasons. First, only iNOS produces micromolar NO concentrations, amounts that are high by comparison with the picomolar to nanomolar concentrations resulting from Ca2+-controlled NO production by endothelial eNOS or neuronal nNOS. Second, iNOS is not constitutively expressed in cells and regulation of this isoenzyme, in contrast to endothelial eNOS or neuronal nNOS, is widely considered to occur at the transcriptional level only. In particular, we were interested in the possibility that caveolin-1, a protein that functions as a tumor suppressor in colon carcinoma cells (Bender et al., 2002; this issue, might regulate iNOS activity. Our results provide evidence for the existence of a post-transcriptional mechanism controlling iNOS protein levels that involves caveolin-1-dependent sequestration of iNOS within a detergent-insoluble compartment. Interestingly, despite the high degree of conservation of the caveolin-1 scaffolding domain binding motif within all NOS enzymes, the interaction detected between caveolin-1 and iNOS in vitro is crucially dependent on presence of a caveolin-1 sequence element immediately adjacent to the scaffolding domain. A model is presented summarizing the salient aspects of these results. These observations are important in the context of tumor biology, since down-regulation of caveolin-1 is predicted to promote uncontrolled iNOS activity, genotoxic damage and thereby facilitate tumor development in humans

  1. Dynamic MR imaging: Follow-up study after femoral head core decompression and rhBMP-2 instillation in patients with avascular necrosis of the femoral head; Dynamische Magnetresonanztomographie (MRT): Verlaufsbeobachtung nach Femurkerndekompression und Auffuellung mit rekombinantem, humanem Bone morphogenetic Protein-2 (rhBMP-2) bei avaskulaerer Femurkopfnekrose

    Energy Technology Data Exchange (ETDEWEB)

    Schedel, H. [Klinik Prof. Schedel, Kellberg (Germany); Schneller, A. [Humboldt-Universitaet, Berlin (Germany). Klinik fuer Allgemein- und Transplantationschirurgie; Vogl, T.; Mueller, H.F.; Maeurer, J.; Felix, R. [Humboldt-Universitaet, Berlin (Germany). Strahlenklinik und Poliklinik; Suedkamp, N. [Humboldt-Universitaet, Berlin (Germany). Unfall- und Wiederherstellungschirurgie; Eisenschenk, A. [Freie Univ. Berlin (Germany). Orthopaedische Klinik und Poliklinik

    2000-07-01

    Material and Methods: Six patients with avascular necrosis of the femoral head ARCO-stage I- or II-lesions were treated surgically by femoral head core decompression. Three of these patients were additionally treated with rhBMP-2-instillation. The progression or regression could be confirmed by T1- and T2-weighted spinecho-sequences (zero, four, ten, sixteen weeks and 24 months follow up). Results: Corresponding ARCO-classification with partly more sensitive measurement of vitality signs in comparison to the optical X-ray classification. The objective, quantitative measurement of signalintensity post contrast medium reduces the influence of experience and level of education. The dynamic sequences results are reproducable. (orig.) [German] Material und Methoden: Sechs Patienten mit avaskulaerer Nekrose des Femurkopfes des Stadiums I oder II nach ARCO wurden einer Femurkerndekompression unterzogen. Drei dieser Patienten erhielten zusaetzlich eine rhBMP-2-Auffuellung. Zum Zeitpunkt null, vier, zehn, sechszehn Wochen und 24 Monaten post OP erfolgte die kernspintomographische Untersuchung mit T1- und T2-gewichteten Sequenzen unter besonderer Beruecksichtigung der dynamischen Untersuchungssequenz nach Gabe von Gd-DTPA (Gadopentetsaeure, Dimegluminsalz; Magnevist {sup trademark}) zur Dokumentation der Signalintensitaetssteigerung pro Zeiteinheit in der Nekroseregion. Ergebnisse: Uebereinstimmende Stadienklassifikation nach ARCO mit zum Teil empfindlicherer Messung von Vitalitaetszeichen im Vergleich zu rein visuellen roentgenologischen Einteilung. Die objektive, quantitative Messung des Signalintensitaetssteigerungsverhaltens nach Kontrastmittelgabe im Bereich der Femurkopfnekrose kann den Einfluss von subjektiven Eigenschaften des Untersuchers (Erfahrung, Ausbildungsstand) reduzieren, wobei die Ergebnisse der Dynamiksequenzen objektiv reproduzierbar sind. (orig.)

  2. Enhanced angiogenesis and osteogenesis in critical bone defects by the controlled release of BMP-2 and VEGF: implantation of electron beam melting-fabricated porous Ti6Al4V scaffolds incorporating growth factor-doped fibrin glue

    International Nuclear Information System (INIS)

    Lv, Jia; Xiu, Peng; Tan, Jie; Cai, Hong; Liu, Zhongjun; Jia, Zhaojun

    2015-01-01

    Electron beam melting (EBM)-fabricated porous titanium implants possessing low elastic moduli and tailored structures are promising biomaterials for orthopedic applications. However, the bio-inert nature of porous titanium makes reinforcement with growth factors (GFs) a promising method to enhance implant in vivo performance. Bone-morphogenic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) are key factors of angiogenesis and osteogenesis. Therefore, the present study is aimed at evaluating EBM-fabricated porous titanium implants incorporating GF-doped fibrin glue (FG) as composite scaffolds providing GFs for improvement of angiogenesis and osteogenesis in rabbit femoral condyle defects. BMP-2 and VEGF were added into the constituent compounds of FG, and then this GF-doped FG was subsequently injected into the porous scaffolds. In five groups of implants, angiogenesis and osteogenesis were evaluated at 4 weeks post-implantation using Microfil perfusion and histological analysis: eTi (empty scaffolds), cTi (containing undoped FG), BMP/cTi (containing 50 μg rhBMP-2), VEGF/cTi (containing 0.5 μg VEGF) and Dual/cTi (containing 50 μg rhBMP-2 and 0.5 μg VEGF). The results demonstrate that these composite implants are biocompatible and provide the desired gradual release of the bioactive growth factors. Incorporation of GF delivery, whether a single factor or dual factors, significantly enhanced both angiogenesis and osteogenesis inside the porous scaffolds. However, the synergistic effect of the dual factors combination was observable on angiogenesis but absent on osteogenesis. In conclusion, fibrin glue is a biocompatible material that could be employed as a delivery vehicle in EBM-fabricated porous titanium for controlled release of BMP-2 and VEGF. Application of this method for loading a porous titanium scaffold to incorporate growth factors is a convenient and promising strategy for improving osteogenesis of critical-sized bone defects

  3. Tumor protein D52 expression is post-transcriptionally regulated by T-cell intercellular antigen (TIA) 1 and TIA-related protein via mRNA stability.

    Science.gov (United States)

    Motohashi, Hiromi; Mukudai, Yoshiki; Ito, Chihiro; Kato, Kosuke; Shimane, Toshikazu; Kondo, Seiji; Shirota, Tatsuo

    2017-05-04

    Although tumor protein D52 (TPD52) family proteins were first identified nearly 20 years ago, their molecular regulatory mechanisms remain unclear. Therefore, we investigated the post-transcriptional regulation of TPD52 family genes. An RNA immunoprecipitation (RIP) assay showed the potential binding ability of TPD52 family mRNAs to several RNA-binding proteins, and an RNA degradation assay revealed that TPD52 is subject to more prominent post-transcriptional regulation than are TPD53 and TPD54. We subsequently focused on the 3'-untranslated region (3'-UTR) of TPD52 as a cis -acting element in post-transcriptional gene regulation. Several deletion mutants of the 3'-UTR of TPD52 mRNA were constructed and ligated to the 3'-end of a reporter green fluorescence protein gene. An RNA degradation assay revealed that a minimal cis -acting region, located in the 78-280 region of the 5'-proximal region of the 3'-UTR, stabilized the reporter mRNA. Biotin pull-down and RIP assays revealed specific binding of the region to T-cell intracellular antigen 1 (TIA-1) and TIA-1-related protein (TIAR). Knockdown of TIA-1/TIAR decreased not only the expression, but also the stability of TPD52 mRNA; it also decreased the expression and stability of the reporter gene ligated to the 3'-end of the 78-280 fragment. Stimulation of transforming growth factor-β and epidermal growth factor decreased the binding ability of these factors, resulting in decreased mRNA stability. These results indicate that the 78-280 fragment and TIA-1/TIAR concordantly contribute to mRNA stability as a cis -acting element and trans -acting factor(s), respectively. Thus, we here report the specific interactions between these elements in the post-transcriptional regulation of the TPD52 gene. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  4. Nitrite reductase expression is regulated at the post-transcriptional level by the nitrogen source in Nicotiana plumbaginifolia and Arabidopsis thaliana.

    Science.gov (United States)

    Crété, P; Caboche, M; Meyer, C

    1997-04-01

    Higher plant nitrite reductase (NiR) is a monomeric chloroplastic protein catalysing the reduction of nitrite, the product of nitrate reduction, to ammonium. The expression of this enzyme is controlled at the transcriptional level by light and by the nitrogen source. In order to study the post-transcriptional regulation of NiR, Nicotiana plumbaginifolia and Arabidopsis thaliana were transformed with a chimaeric NiR construct containing the tobacco leaf NiR1 coding sequence driven by the CaMV 35S RNA promoter. Transformed plants did not show any phenotypic difference when compared with the wild-type, although they overexpressed NiR activity in the leaves. When these plants were grown in vitro on media containing either nitrate or ammonium as sole nitrogen source, NiR mRNA derived from transgene expression was constitutively expressed, whereas NiR activity and protein level were strongly reduced on ammonium-containing medium. These results suggest that, together with transcriptional control, post-transcriptional regulation by the nitrogen source is operating on NiR expression. This post-transcriptional regulation of tobacco leaf NiR1 expression was observed not only in the closely related species N. plumbaginifolia but also in the more distant species A. thaliana.

  5. The gga-let-7 family post-transcriptionally regulates TGFBR1 and LIN28B during the differentiation process in early chick development.

    Science.gov (United States)

    Lee, Sang In; Jeon, Mi-Hyang; Kim, Jeom Sun; Jeon, Ik-Soo; Byun, Sung June

    2015-12-01

    Early chick embryogenesis is governed by a complex mechanism involving transcriptional and post-transcriptional regulation, although how post-transcriptional processes influence the balance between pluripotency and differentiation during early chick development have not been previously investigated. Here, we characterized the microRNA (miRNA) signature associated with differentiation in the chick embryo, and found that as expression of the gga-let-7 family increases through early development, expression of their direct targets, TGFBR1 and LIN28B, decreases; indeed, gga-let-7a-5p and gga-let-7b miRNAs directly bind to TGFBR1 and LIN28B transcripts. Our data further indicate that TGFBR1 and LIN28B maintain pluripotency by regulating POUV, NANOG, and CRIPTO. Therefore, gga-let-7 miRNAs act as post-transcriptional regulators of differentiation in blastodermal cells by repressing the expression of the TGFBR1 and LIN28B, which intrinsically controls blastodermal cell differentiation in early chick development. © 2015 Wiley Periodicals, Inc.

  6. Breast cancer cells obtain an osteomimetic feature via epithelial-mesenchymal transition that have undergone BMP2/RUNX2 signaling pathway induction.

    Science.gov (United States)

    Tan, Cong-Cong; Li, Gui-Xi; Tan, Li-Duan; Du, Xin; Li, Xiao-Qing; He, Rui; Wang, Qing-Shan; Feng, Yu-Mei

    2016-11-29

    Bone is one of the most common organs of breast cancer metastasis. Cancer cells that mimic osteoblasts by expressing bone matrix proteins and factors have a higher likelihood of metastasizing to bone. However, the molecular mechanisms of osteomimicry formation of cancer cells remain undefined. Herein, we identified a set of bone-related genes (BRGs) that are ectopically co-expressed in primary breast cancer tissues and determined that osteomimetic feature is obtained due to the osteoblast-like transformation of epithelial breast cancer cells that have undergone epithelial-mesenchymal transition (EMT) followed by bone morphogenetic protein-2 (BMP2) stimulation. Furthermore, we demonstrated that breast cancer cells that transformed into osteoblast-like cells with high expression of BRGs showed enhanced chemotaxis, adhesion, proliferation and multidrug resistance in an osteoblast-mimic bone microenvironment in vitro. During these processes, runt-related transcription factor 2 (RUNX2) functioned as a master mediator by suppressing or activating the transcription of BRGs that underlie the dynamic antagonism between the TGF-β/SMAD and BMP/SMAD signaling pathways in breast cancer cells. Our findings suggest a novel mechanism of osteomimicry formation that arises in primary breast tumors, which may explain the propensity of breast cancer to metastasize to the skeleton and contribute to potential strategies for predicting and targeting breast cancer bone metastasis and multidrug resistance.

  7. A Novel Human TGF-β1 Fusion Protein in Combination with rhBMP-2 Increases Chondro-Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Silvia Claros

    2014-06-01

    Full Text Available Transforming growth factor-beta (TGF-β is involved in processes related to the differentiation and maturation of osteoprogenitor cells into osteoblasts. Rat bone marrow (BM cells were cultured in a collagen-gel containing 0.5% fetal bovine serum (FBS for 10 days in the presence of rhTGF (recombinant human TGF-β1-F2, a fusion protein engineered to include a high-affinity collagen-binding decapeptide derived from von Willebrand factor. Subsequently, cells were moderately expanded in medium with 10% FBS for 4 days and treated with a short pulse of rhBMP (recombinant human bone morphogenetic protein-2 for 4 h. During the last 2 days, dexamethasone and β-glycerophosphate were added to potentiate osteoinduction. Concomitant with an up-regulation of cell proliferation, DNA synthesis levels were determined. Polymerase chain reaction was performed to reveal the possible stemness of these cells. Osteogenic differentiation was evaluated in terms of alkaline phosphatase activity and mineralized matrix formation as well as by mRNA expression of osteogenic marker genes. Moreover, cells were placed inside diffusion chambers and implanted subcutaneously into the backs of adult rats for 4 weeks. Histological study provided evidence of cartilage and bone-like tissue formation. This experimental procedure is capable of selecting cell populations from BM that, in the presence of rhTGF-β1-F2 and rhBMP-2, achieve skeletogenic potential in vitro and in vivo.

  8. BMP-2, hypoxia, and COL1A1/HtrA1 siRNAs favor neo-cartilage hyaline matrix formation in chondrocytes.

    Science.gov (United States)

    Ollitrault, David; Legendre, Florence; Drougard, Carole; Briand, Mélanie; Benateau, Hervé; Goux, Didier; Chajra, Hanane; Poulain, Laurent; Hartmann, Daniel; Vivien, Denis; Shridhar, Vijayalakshmi; Baldi, Alfonso; Mallein-Gerin, Frédéric; Boumediene, Karim; Demoor, Magali; Galera, Philippe

    2015-02-01

    Osteoarthritis (OA) is an irreversible pathology that causes a decrease in articular cartilage thickness, leading finally to the complete degradation of the affected joint. The low spontaneous repair capacity of cartilage prevents any restoration of the joint surface, making OA a major public health issue. Here, we developed an innovative combination of treatment conditions to improve the human chondrocyte phenotype before autologous chondrocyte implantation. First, we seeded human dedifferentiated chondrocytes into a collagen sponge as a scaffold, cultured them in hypoxia in the presence of a bone morphogenetic protein (BMP), BMP-2, and transfected them with small interfering RNAs targeting two markers overexpressed in OA dedifferentiated chondrocytes, that is, type I collagen and/or HtrA1 serine protease. This strategy significantly decreased mRNA and protein expression of type I collagen and HtrA1, and led to an improvement in the chondrocyte phenotype index of differentiation. The effectiveness of our in vitro culture process was also demonstrated in the nude mouse model in vivo after subcutaneous implantation. We, thus, provide here a new protocol able to favor human hyaline chondrocyte phenotype in primarily dedifferentiated cells, both in vitro and in vivo. Our study also offers an innovative strategy for chondrocyte redifferentiation and opens new opportunities for developing therapeutic targets.

  9. Surface modification of 3D-printed porous scaffolds via mussel-inspired polydopamine and effective immobilization of rhBMP-2 to promote osteogenic differentiation for bone tissue engineering.

    Science.gov (United States)

    Lee, Sang Jin; Lee, Donghyun; Yoon, Taek Rim; Kim, Hyung Keun; Jo, Ha Hyeon; Park, Ji Sun; Lee, Jun Hee; Kim, Wan Doo; Kwon, Il Keun; Park, Su A

    2016-08-01

    For tissue engineering, a bio-porous scaffold which is applied to bone-tissue regeneration should provide the hydrophilicity for cell attachment as well as provide for the capability to bind a bioactive molecule such as a growth factor in order to improve cell differentiation. In this work, we prepared a three-dimensional (3D) printed polycaprolactone scaffold (PCLS) grafted with recombinant human bone morphogenic protein-2 (rhBMP2) attached via polydopamine (DOPA) chemistry. The DOPA coated PCL scaffold was characterized by contact angle, water uptake, and X-ray photoelectron spectroscopy (XPS) in order to certify that the surface was successfully coated with DOPA. In order to test the loading and release of rhBMP2, we examined the release rate for 28days. For the In vitro cell study, pre-osteoblast MC3T3-E1 cells were seeded onto PCL scaffolds (PCLSs), DOPA coated PCL scaffold (PCLSD), and scaffolds with varying concentrations of rhBMP2 grafted onto the PCLSD 100 and PCLSD 500 (100 and 500ng/ml loaded), respectively. These scaffolds were evaluated by cell proliferation, alkaline phosphatase activity, and real time polymerase chain reaction with immunochemistry in order to verify their osteogenic activity. Through these studies, we demonstrated that our fabricated scaffolds were well coated with DOPA as well as grafted with rhBMP2 at a quantity of 22.7±5ng when treatment with 100ng/ml rhBMP2 and 153.3±2.4ng when treated with 500ng/ml rhBMP2. This grafting enables rhBMP2 to be released in a sustained pattern. In the in vitro results, the cell proliferation and an osteoconductivity of PCLSD 500 groups was greater than any other group. All of these results suggest that our manufactured 3D printed porous scaffold would be a useful construct for application to the bone tissue engineering field. Tissue-engineered scaffolds are not only extremely complex and cumbersome, but also use organic solvents which can negatively influence cellular function. Thus, a rapid

  10. The influence of Aloe vera and xenograft XCB toward of bone morpho protein 2 BMP2 expression and amount of osteoblast of alveolar bone induced into tooth extraction sockets Cavia cobaya

    Directory of Open Access Journals (Sweden)

    Utari Kresnoadi

    2014-12-01

    Full Text Available Tooth extraction can cause inflammation leading to alveolar ridge resorption. In addition, prominent ridge has crucial role for making denture su-ccessfully. Thus, socket preservation is needed to prevent greater alveolar ridge resorption. An innovative material, a combination of Aloe vera and xe-nograft (XCB, is then considered as a biogenic stimulator that can reduce inflammation, as a result, the growth of alveolar bone is expected to be impro-ved. This research is aimed to prove whether the mixture of Aloe vera and xenograft can stimulate BMP2 and increase osteoblasts. Forty-eight Cavia co-baya animals were divided into eight groups each of which consisted of six animals. The mandibular incisors of those Cavia cobaya animals were then extracted and filled with PEG as Group Control, XCB as Group XCB, Aloe vera as Group Aloe vera, and a combination of Aloe vera +XCB as Group Aloe vera +XCB. Next, the first four groups were sacrificed seven days after extraction, and the second four groups were sacrificed 30 days after extrac-tion. And then, immunohistochemical and histopathology examinations were conducted to examine BMP2 expression and osteoblasts. Based on the re-sult known that the mixture of Aloe vera and xenograft can increase BMP2 expression and amount of osteoblasts. It can be concluded that the mixture of Aloe vera and xenograft can increase BMP2 expression and amount of osteoblast cel . It can be used as an alternative material to increase the growth of alveolar bone after extraction.

  11. Histological and radiographic evaluation of the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2 in a scaffold of inorganic bone and after stimulation with low-power laser light

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    Bengtson Antonio

    2010-01-01

    Full Text Available Objective: The present study histologically and radiologically evaluates the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2 in a natural inorganic bone mineral scaffold from a bull calf femur and irradiation with low-power light laser. Materials and Methods: The right and left hind limbs of 16 rats were shaved and an incision was made in the muscle on the face corresponding to the median portion of the tibia, into which rhBMP-2 in a scaffold of inorganic bone was implanted. Two groups of limbs were formed: control (G1 and laser irradiation (G2. G2 received diode laser light applied in the direction of the implant, at a dose of 8 J/cm2 for three minutes. On the 7th, 21st, 40th and 112th days after implantation, hind limbs of 4 animals were radiographed and their implants removed together with the surrounding tissue for study under the microscope. The histological results were graded as 0=absence, 1=slight presence, 2=representative and 3=very representative, with regard to the following events: formation of osteoid structure, acute inflammation, chronic inflammation, fibrin deposition, neovascularization, foreign-body granuloma and fibrosis. Results: There were no statistically significant differences in these events at each evaluation times, between the two groups (P > 0.05; Mann-Whitney test. Nevertheless, it could be concluded that the natural inorganic bone matrix with rhBMP-2, from the femur of a bull calf, is a biocompatible combination. Conclusions: Under these conditions, the inductive capacity of rhBMP-2 for cell differentiation was inhibited. There was a slight acceleration in tissue healing in the group that received irradiation with low-power laser light.

  12. Complex and extensive post-transcriptional regulation revealed by integrative proteomic and transcriptomic analysis of metabolite stress response in Clostridium acetobutylicum.

    Science.gov (United States)

    Venkataramanan, Keerthi P; Min, Lie; Hou, Shuyu; Jones, Shawn W; Ralston, Matthew T; Lee, Kelvin H; Papoutsakis, E Terry

    2015-01-01

    Clostridium acetobutylicum is a model organism for both clostridial biology and solvent production. The organism is exposed to its own toxic metabolites butyrate and butanol, which trigger an adaptive stress response. Integrative analysis of proteomic and RNAseq data may provide novel insights into post-transcriptional regulation. The identified iTRAQ-based quantitative stress proteome is made up of 616 proteins with a 15 % genome coverage. The differentially expressed proteome correlated poorly with the corresponding differential RNAseq transcriptome. Up to 31 % of the differentially expressed proteins under stress displayed patterns opposite to those of the transcriptome, thus suggesting significant post-transcriptional regulation. The differential proteome of the translation machinery suggests that cells employ a different subset of ribosomal proteins under stress. Several highly upregulated proteins but with low mRNA levels possessed mRNAs with long 5'UTRs and strong RBS scores, thus supporting the argument that regulatory elements on the long 5'UTRs control their translation. For example, the oxidative stress response rubrerythrin was upregulated only at the protein level up to 40-fold without significant mRNA changes. We also identified many leaderless transcripts, several displaying different transcriptional start sites, thus suggesting mRNA-trimming mechanisms under stress. Downregulation of Rho and partner proteins pointed to changes in transcriptional elongation and termination under stress. The integrative proteomic-transcriptomic analysis demonstrated complex expression patterns of a large fraction of the proteome. Such patterns could not have been detected with one or the other omic analyses. Our analysis proposes the involvement of specific molecular mechanisms of post-transcriptional regulation to explain the observed complex stress response.

  13. Isoforms of elongation factor eEF1A may be differently regulated at post-transcriptional level in breast cancer progression

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    Vislovukh A. A.

    2013-01-01

    Full Text Available Eukaryotic translation elongation factor 1A exists as two 98 % homologous isoforms: eEF1A1 (A1 and eEF1A2 (A2 which are tissue and development specific. Despite high homology in an open reading frame (ORF region, mRNAs coding for eEF1A1 and eEF1A2 are different in their untranslated regions (UTR, suggesting a possibility of their dissimilar post-transcriptional regulation. Aim. To analyze the existence of cis-acting motifs in the UTRs of EEF1A1/A2 mRNAs, to confirm the possibility of post-transcriptional control of eEF1A1 and eEF1A2 expression. Methods. An ensemble of bioinformatic methods was applied to predict regulatory motifs in the UTRs of EEF1A1/A2 mRNAs. Dual-luciferase reporter assay was employed to detect post-transcriptional regulation of eEF1A1/A2 expression. Results. Numerous regulatory motifs in the UTR of EEF1A1/A2 mRNAs were found bioinformatically. The experimental evidence was obtained for the existence of negative regulation of EEF1A1 and positive regulation of EEF1A2 mRNA in the model of breast cancer development. Conclusions. EEF1A1 and EEF1A2 mRNAs contain distinct motifs in the UTRs and are differently regulated in cancer suggesting the possibility of their control by different cellular signals.

  14. Influence of Poly(L-Lactic Acid Nanofibers and BMP-2–Containing Poly(L-Lactic Acid Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

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    Markus D. Schofer

    2008-01-01

    Full Text Available The aim of this study was to characterize synthetic poly-(L-lactic acid (PLLA nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP, osteocalcin (OC, and collagen I (COL-I. Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form.

  15. Influence of Poly(L-Lactic Acid) Nanofibers and BMP-2–Containing Poly(L-Lactic Acid) Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

    Science.gov (United States)

    Schofer, Markus D.; Fuchs-Winkelmann, Susanne; Gräbedünkel, Christian; Wack, Christina; Dersch, Roland; Rudisile, Markus; Wendorff, Joachim H.; Greiner, Andreas; Paletta, Jürgen R. J.; Boudriot, Ulrich

    2008-01-01

    The aim of this study was to characterize synthetic poly-(L-lactic acid) (PLLA) nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and collagen I (COL-I). Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form. PMID:19112539

  16. A heterozygous microdeletion of 20p12.2-3 encompassing PROKR2 and BMP2 in a patient with congenital hypopituitarism and growth hormone deficiency.

    Science.gov (United States)

    Parsons, Samuel J H; Wright, Neville B; Burkitt-Wright, Emma; Skae, Mars S; Murray, Phillip G

    2017-08-01

    Congenital growth hormone deficiency is a rare disorder with an incidence of approximately 1 in 4,000 live births. Pituitary development is under the control of a multitude of spatiotemporally regulated signaling molecules and transcription factors. Mutations in the genes encoding these molecules can result in hypopituitarism but for the majority of children with congenital hypopituitarism, the aetiology of their disease remains unknown. The proband is a 5-year-old girl who presented with neonatal hypoglycaemia and prolonged jaundice. No definitive endocrine cause of hypoglycaemia was identified in the neonatal period. She was born of normal size at 42 weeks but demonstrated growth failure with a progressive reduction in height to -3.2 SD by age 4.5 years and failed a growth hormone stimulation test with a peak growth hormone of 4.2 mcg/L. MRI of the pituitary gland demonstrated a hypoplastic anterior lobe and ectopic posterior lobe. Array CGH demonstrated an inherited 0.2 Mb gain at 1q21.1 and a de novo 4.8 Mb heterozygous deletion at 20p12.2-3. The deletion contained 17 protein coding genes including PROKR2 and BMP2, both of which are expressed during embryological development of the pituitary gland. PROKR2 mutations have been associated with hypopituitarism but a heterozygous deletion of this gene with hypopituitarism is a novel observation. In conclusion, congenital hypopituitarism can be present in individuals with a 20p12.3 deletion, observed with incomplete penetrance. Array CGH may be a useful investigation in select cases of early onset growth hormone deficiency, and patients with deletions within this region should be evaluated for pituitary hormone deficiencies. © 2017 Wiley Periodicals, Inc.

  17. An sRNA and Cold Shock Protein Homolog-Based Feedforward Loop Post-transcriptionally Controls Cell Cycle Master Regulator CtrA.

    Science.gov (United States)

    Robledo, Marta; Schlüter, Jan-Philip; Loehr, Lars O; Linne, Uwe; Albaum, Stefan P; Jiménez-Zurdo, José I; Becker, Anke

    2018-01-01

    Adjustment of cell cycle progression is crucial for bacterial survival and adaptation under adverse conditions. However, the understanding of modulation of cell cycle control in response to environmental changes is rather incomplete. In α-proteobacteria, the broadly conserved cell cycle master regulator CtrA underlies multiple levels of control, including coupling of cell cycle and cell differentiation. CtrA levels are known to be tightly controlled through diverse transcriptional and post-translational mechanisms. Here, small RNA (sRNA)-mediated post-transcriptional regulation is uncovered as an additional level of CtrA fine-tuning. Computational predictions as well as transcriptome and proteome studies consistently suggested targeting of ctrA and the putative cold shock chaperone cspA5 mRNAs by the trans- encoded sRNA ( trans- sRNA) GspR (formerly SmelC775) in several Sinorhizobium species. GspR strongly accumulated in the stationary growth phase, especially in minimal medium (MM) cultures. Lack of the gspR locus confers a fitness disadvantage in competition with the wild type, while its overproduction hampers cell growth, suggesting that this riboregulator interferes with cell cycle progression. An eGFP-based reporter in vivo assay, involving wild-type and mutant sRNA and mRNA pairs, experimentally confirmed GspR-dependent post-transcriptional down-regulation of ctrA and cspA5 expression, which most likely occurs through base-pairing to the respective mRNA. The energetically favored secondary structure of GspR is predicted to comprise three stem-loop domains, with stem-loop 1 and stem-loop 3 targeting ctrA and cspA5 mRNA, respectively. Moreover, this work reports evidence for post-transcriptional control of ctrA by CspA5. Thus, this regulation and GspR-mediated post-transcriptional repression of ctrA and cspA5 expression constitute a coherent feed-forward loop, which may enhance the negative effect of GspR on CtrA levels. This novel regulatory circuit involving

  18. Pou1f1, the key transcription factor related to somatic growth in tilapia (Orechromis niloticus), is regulated by two independent post-transcriptional regulation mechanisms.

    Science.gov (United States)

    Wang, Dongfang; Qin, Jingkai; Jia, Jirong; Yan, Peipei; Li, Wensheng

    2017-01-29

    This study aims to determine the post-transcriptional regulation mechanism of the transcription factor pou1f1 (pou class 1 homeobox 1), which is the key gene for pituitary development, somatic growth in vertebrates, and transcription of several hormone genes in teleost fish. MicroRNA miR-223-3p was identified as a bona fide target of pou1f; overexpression of miR-223-3p in primary pituitary cells led to the down-regulation of pou1f1 and downstream genes, and inhibition of miR-223-3p led to the up-regulation of pou1f1 in Nile tilapia dispersed primary pituitary cells. An adenylate-uridylate-rich element (AU-Rich element) was found in the 3'UTR of pou1f1 mRNA, and deletion of the AU-Rich element led to slower mRNA decay and therefore more protein output. A potential mutual relationship between miR-223-3p and the AU-rich element was also investigated, and the results demonstrated that with or without the AU-Rich element, miR-223-3p induced the up-regulation of a reporter system under serum starvation conditions, indicating that miR-223-3p and the AU-Rich element function independent of each other. This study is the first to investigate the post-transcriptional mechanism of pou1f1, which revealed that miR-223-3p down-regulated pou1f1 and downstream gene expressions, and the AU-Rich element led to rapid decay of pou1f1 mRNA. MicroRNA miR-223-3p and the AU-Rich element co-regulated the post-transcriptional expression of pou1f1 independently in Nile tilapia, demonstrating that pou1f1 is under the control of a dual post-transcription regulation mechanism. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Icaritin inhibits the expression of alpha-fetoprotein in hepatitis B virus-infected hepatoma cell lines through post-transcriptional regulation.

    Science.gov (United States)

    Zhang, Chao; Li, Hui; Jiang, Wei; Zhang, Xiaowei; Li, Gang

    2016-12-13

    Although it has showed that icaritin can apparently suppress growth of HCC by reducing the level of AFP, the intrinsic mechanism remains unclear. In this study, we explored the possible mechanism of miRNAs on post-transcriptional regulation of AFP gene, as well as the effects of HBV infection and icaritin in hepatoma cells. The results showed that miR-620, miR-1236 and miR-1270 could bind target sites in the range of 9-18 nt and 131-151 nt downstream of the stop codon in the AFP mRNA 3'-UTR to suppress the expression of AFP. Mutation of these target sites could reverse the effects of these miRNAs. Icaritin (10 μM) might reduce the stability and translational activity of AFP mRNA by increasing the expression levels of these mentioned miRNAs. HBV infection resulted in apparent decreases of these miRNAs and, consequently, increased AFP expression. The results indicated that miR-620, miR-1236 and miR-1270 are critical factors in the post-transcriptional regulation of AFP. Icaritin can counteract the effect of HBV. These findings will contribute to full understanding of the regulatory mechanism of AFP expression in hepatoma cells. And also it revealed a synergistic mechanism of HBV infection and elevation of AFP in the pathogenesis of HCC, as well as the potential clinical significance of icaritin on the therapy of HCC induced by HBV.

  20. Quantitative proteomics unravels that the post-transcriptional regulator Crc modulates the generation of vesicles and secreted virulence determinants of Pseudomonas aeruginosa.

    Science.gov (United States)

    Reales-Calderón, Jose Antonio; Corona, Fernando; Monteoliva, Lucía; Gil, Concha; Martínez, Jose Luis

    2015-09-08

    Recent research indicates that the post-transcriptional regulator Crc modulates susceptibility to antibiotics and virulence in Pseudomonas aeruginosa. Several P. aeruginosa virulence factors are secreted or engulfed in vesicles. To decipher the Crc modulation of P. aeruginosa virulence, we constructed a crc deficient mutant and measure the proteome associated extracellular vesicles and the vesicle-free secretome using iTRAQ. Fifty vesicle-associated proteins were more abundant and 14 less abundant in the crc-defective strain, whereas 37 were more abundant and 17 less abundant in the vesicle-free secretome. Among them, virulence determinants, such as ToxA, protease IV, azurin, chitin-binding protein, PlcB and Hcp1, were less abundant in the crc-defective mutant. Transcriptomic analysis revealed that some of the observed changes were post-transcriptional and, thus, could be attributed to a direct Crc regulatory role; whereas, for other differentially secreted proteins, the regulatory role was likely indirect. We also observed that the crc mutant presented an impaired vesicle-associated secretion of quorum sensing signal molecules and less cytotoxicity than its wild-type strain. Our results offer new insights into the mechanisms by which Crc regulates P. aeruginosa virulence, through the modulation of vesicle formation and secretion of both virulence determinants and quorum sensing signals. This article is part of a Special Issue entitled: HUPO 2014. Published by Elsevier B.V.

  1. Widespread anti-sense transcription in apple is correlated with siRNA production and indicates a large potential for transcriptional and/or post-transcriptional control.

    Science.gov (United States)

    Celton, Jean-Marc; Gaillard, Sylvain; Bruneau, Maryline; Pelletier, Sandra; Aubourg, Sébastien; Martin-Magniette, Marie-Laure; Navarro, Lionel; Laurens, François; Renou, Jean-Pierre

    2014-07-01

    Characterizing the transcriptome of eukaryotic organisms is essential for studying gene regulation and its impact on phenotype. The realization that anti-sense (AS) and noncoding RNA transcription is pervasive in many genomes has emphasized our limited understanding of gene transcription and post-transcriptional regulation. Numerous mechanisms including convergent transcription, anti-correlated expression of sense and AS transcripts, and RNAi remain ill-defined. Here, we have combined microarray analysis and high-throughput sequencing of small RNAs (sRNAs) to unravel the complexity of transcriptional and potential post-transcriptional regulation in eight organs of apple (Malus × domestica). The percentage of AS transcript expression is higher than that identified in annual plants such as rice and Arabidopsis thaliana. Furthermore, we show that a majority of AS transcripts are transcribed beyond 3'UTR regions, and may cover a significant portion of the predicted sense transcripts. Finally we demonstrate at a genome-wide scale that anti-sense transcript expression is correlated with the presence of both short (21-23 nt) and long (> 30 nt) siRNAs, and that the sRNA coverage depth varies with the level of AS transcript expression. Our study provides a new insight on the functional role of anti-sense transcripts at the genome-wide level, and a new basis for the understanding of sRNA biogenesis in plants. © 2014 INRA. New Phytologist © 2014 New Phytologist Trust.

  2. AGO1, QDE-2, and RDE-1 are related proteins required for post-transcriptional gene silencing in plants, quelling in fungi, and RNA interference in animals.

    Science.gov (United States)

    Fagard, M; Boutet, S; Morel, J B; Bellini, C; Vaucheret, H

    2000-10-10

    Introduction of transgene DNA may lead to specific degradation of RNAs that are homologous to the transgene transcribed sequence through phenomena named post-transcriptional gene silencing (PTGS) in plants, quelling in fungi, and RNA interference (RNAi) in animals. It was shown previously that PTGS, quelling, and RNAi require a set of related proteins (SGS2, QDE-1, and EGO-1, respectively). Here we report the isolation of Arabidopsis mutants impaired in PTGS which are affected at the Argonaute1 (AGO1) locus. AGO1 is similar to QDE-2 required for quelling and RDE-1 required for RNAi. Sequencing of ago1 mutants revealed one amino acid essential for PTGS that is also present in QDE-2 and RDE-1 in a highly conserved motif. Taken together, these results confirm the hypothesis that these processes derive from a common ancestral mechanism that controls expression of invading nucleic acid molecules at the post-transcriptional level. As opposed to rde-1 and qde-2 mutants, which are viable, ago1 mutants display several developmental abnormalities, including sterility. These results raise the possibility that PTGS, or at least some of its elements, could participate in the regulation of gene expression during development in plants.

  3. The RNA-binding protein Celf1 post-transcriptionally regulates p27Kip1 and Dnase2b to control fiber cell nuclear degradation in lens development.

    Directory of Open Access Journals (Sweden)

    Archana D Siddam

    2018-03-01

    Full Text Available Opacification of the ocular lens, termed cataract, is a common cause of blindness. To become transparent, lens fiber cells undergo degradation of their organelles, including their nuclei, presenting a fundamental question: does signaling/transcription sufficiently explain differentiation of cells progressing toward compromised transcriptional potential? We report that a conserved RNA-binding protein Celf1 post-transcriptionally controls key genes to regulate lens fiber cell differentiation. Celf1-targeted knockout mice and celf1-knockdown zebrafish and Xenopus morphants have severe eye defects/cataract. Celf1 spatiotemporally down-regulates the cyclin-dependent kinase (Cdk inhibitor p27Kip1 by interacting with its 5' UTR and mediating translation inhibition. Celf1 deficiency causes ectopic up-regulation of p21Cip1. Further, Celf1 directly binds to the mRNA of the nuclease Dnase2b to maintain its high levels. Together these events are necessary for Cdk1-mediated lamin A/C phosphorylation to initiate nuclear envelope breakdown and DNA degradation in fiber cells. Moreover, Celf1 controls alternative splicing of the membrane-organization factor beta-spectrin and regulates F-actin-crosslinking factor Actn2 mRNA levels, thereby controlling fiber cell morphology. Thus, we illustrate new Celf1-regulated molecular mechanisms in lens development, suggesting that post-transcriptional regulatory RNA-binding proteins have evolved conserved functions to control vertebrate oculogenesis.

  4. Exciter switch

    Science.gov (United States)

    Mcpeak, W. L.

    1975-01-01

    A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.

  5. Dual functions of Rift Valley fever virus NSs protein: inhibition of host mRNA transcription and post-transcriptional downregulation of protein kinase PKR.

    Science.gov (United States)

    Ikegami, Tetsuro; Narayanan, Krishna; Won, Sungyong; Kamitani, Wataru; Peters, C J; Makino, Shinji

    2009-09-01

    Rift Valley fever virus (RVFV), which belongs to the genus Phlebovirus, family Bunyaviridae, is a negative-stranded RNA virus carrying a single-stranded, tripartite RNA genome. RVFV is an important zoonotic pathogen transmitted by mosquitoes and causes large outbreaks among ruminants and humans in Africa and the Arabian Peninsula. Human patients develop an acute febrile illness, followed by a fatal hemorrhagic fever, encephalitis, or ocular diseases. A viral nonstructural protein, NSs, is a major viral virulence factor. Past studies showed that NSs suppresses the transcription of host mRNAs, including interferon-beta mRNAs. Here we demonstrated that the NSs protein induced post-transcriptional downregulation of dsRNA-dependent protein kinase (PKR), to prevent phosphorylation of eIF2alpha and promoted viral translation in infected cells. These two biological activities of the NSs most probably have a synergistic effect in suppressing host innate immune functions and facilitate efficient viral replication in infected mammalian hosts.

  6. The cystic-fibrosis-associated ΔF508 mutation confers post-transcriptional destabilization on the C. elegans ABC transporter PGP-3

    Directory of Open Access Journals (Sweden)

    Liping He

    2012-11-01

    Membrane proteins make up ∼30% of the proteome. During the early stages of maturation, this class of proteins can experience localized misfolding in distinct cellular compartments, such as the cytoplasm, endoplasmic reticulum (ER lumen and ER membrane. ER quality control (ERQC mechanisms monitor folding and determine whether a membrane protein is appropriately folded or is misfolded and warrants degradation. ERQC plays crucial roles in human diseases, such as cystic fibrosis, in which deletion of a single amino acid (F508 results in the misfolding and degradation of the cystic fibrosis transmembrane conductance regulator (CFTR Cl– channel. We introduced the ΔF508 mutation into Caenorhabditis elegans PGP-3, a 12-transmembrane ABC transporter with 15% identity to CFTR. When expressed in intestinal epithelial cells, PGP-3wt was stable and efficiently trafficked to the apical plasma membrane through a COPII-dependent mechanism. However, PGP-3ΔF508 was post-transcriptionally destabilized, resulting in reduced total and apical membrane protein levels. Genetic or physiological activation of the osmotic stress response pathway, which causes accumulation of the chemical chaperone glycerol, stabilized PGP-3ΔF508. Efficient degradation of PGP-3ΔF508 required the function of several C. elegans ER-associated degradation (ERAD homologs, suggesting that destabilization occurs through an ERAD-type mechanism. Our studies show that the ΔF508 mutation causes post-transcriptional destabilization and degradation of PGP-3 in C. elegans epithelial cells. This model, combined with the power of C. elegans genetics, provides a new opportunity to genetically dissect metazoan ERQC.

  7. Pseudospark switches

    International Nuclear Information System (INIS)

    Billault, P.; Riege, H.; Gulik, M. van; Boggasch, E.; Frank, K.

    1987-01-01

    The pseudospark discharge is bound to a geometrical structure which is particularly well suited for switching high currents and voltages at high power levels. This type of discharge offers the potential for improvement in essentially all areas of switching operation: peak current and current density, current rise, stand-off voltage, reverse current capability, cathode life, and forward drop. The first pseudospark switch was built at CERN at 1981. Since then, the basic switching characteristics of pseudospark chambers have been studied in detail. The main feature of a pseudospark switch is the confinement of the discharge plasma to the device axis. The current transition to the hollow electrodes is spread over a rather large surface area. Another essential feature is the easy and precise triggering of the pseudospark switch from the interior of the hollow electrodes, relatively far from the main discharge gap. Nanosecond delay and jitter values can be achieved with trigger energies of less than 0.1 mJ, although cathode heating is not required. Pseudospark gaps may cover a wide range of high-voltage, high-current, and high-pulse-power switching at repetition rates of many kilohertz. This report reviews the basic researh on pseudospark switches which has been going on at CERN. So far, applications have been developed in the range of thyratron-like medium-power switches at typically 20 to 40 kV and 0.5 to 10 kA. High-current pseudospark switches have been built for a high-power 20 kJ pulse generator which is being used for long-term tests of plasma lenses developed for the future CERN Antiproton Collector (ACOL). The high-current switches have operated for several hundred thousand shots, with 20 to 50 ns jitter at 16 kV charging voltage and more than 100 kA peak current amplitude. (orig.)

  8. Post-Transcriptional Regulation of KLF4 by High-Risk Human Papillomaviruses Is Necessary for the Differentiation-Dependent Viral Life Cycle.

    Directory of Open Access Journals (Sweden)

    Vignesh Kumar Gunasekharan

    2016-07-01

    Full Text Available Human papillomaviruses (HPVs are epithelial tropic viruses that link their productive life cycles to the differentiation of infected host keratinocytes. A subset of the over 200 HPV types, referred to as high-risk, are the causative agents of most anogenital malignancies. HPVs infect cells in the basal layer, but restrict viral genome amplification, late gene expression, and capsid assembly to highly differentiated cells that are active in the cell cycle. In this study, we demonstrate that HPV proteins regulate the expression and activities of a critical cellular transcription factor, KLF4, through post-transcriptional and post-translational mechanisms. Our studies show that KLF4 regulates differentiation as well as cell cycle progression, and binds to sequences in the upstream regulatory region (URR to regulate viral transcription in cooperation with Blimp1. KLF4 levels are increased in HPV-positive cells through a post-transcriptional mechanism involving E7-mediated suppression of cellular miR-145, as well as at the post-translational level by E6-directed inhibition of its sumoylation and phosphorylation. The alterations in KLF4 levels and functions results in activation and suppression of a subset of KLF4 target genes, including TCHHL1, VIM, ACTN1, and POT1, that is distinct from that seen in normal keratinocytes. Knockdown of KLF4 with shRNAs in cells that maintain HPV episomes blocked genome amplification and abolished late gene expression upon differentiation. While KLF4 is indispensable for the proliferation and differentiation of normal keratinocytes, it is necessary only for differentiation-associated functions of HPV-positive keratinocytes. Increases in KLF4 levels alone do not appear to be sufficient to explain the effects on proliferation and differentiation of HPV-positive cells indicating that additional modifications are important. KLF4 has also been shown to be a critical regulator of lytic Epstein Barr virus (EBV replication

  9. Identification of novel microRNAs in post-transcriptional control of Nrf2 expression and redox homeostasis in neuronal, SH-SY5Y cells.

    Directory of Open Access Journals (Sweden)

    Madhusudhanan Narasimhan

    Full Text Available Nuclear factor-erythroid 2-related factor 2 (Nrf2/NFE2L2, a redox-sensitive transcription factor plays a critical role in adaptation to cellular stress and affords cellular defense by initiating transcription of antioxidative and detoxification genes. While a protein can be regulated at multiple levels, control of Nrf2 has been largely studied at post-translational regulation points by Keap1. Importantly, post-transcriptional/translational based regulation of Nrf2 is less understood and to date there are no reports on such mechanisms in neuronal systems. In this context, studies involving the role of microRNAs (miRs which are normally considered as fine tuning regulators of protein production through translation repression and/or post-transcriptional alterations, are in place. In the current study, based on in-silico analysis followed by immunoblotting and real time analysis, we have identified and validated for the first time that human NFE2L2 could be targeted by miR153/miR27a/miR142-5p/miR144 in neuronal, SH-SY5Y cells. Co-transfection studies with individual miR mimics along with either WT 3' UTR of human Nrf2 or mutated miRNA targeting seed sequence within Nrf2 3' UTR, demonstrated that Nrf2 is a direct regulatory target of these miRs. In addition, ectopic expression of miR153/miR27a/miR142-5p/miR144 affected Nrf2 mRNA abundance and nucleo-cytoplasmic concentration of Nrf2 in a Keap1 independent manner resulting in inefficient transactivating ability of Nrf2. Furthermore, forced expression of miRs diminished GCLC and GSR expression resulting in alteration of Nrf2 dependent redox homeostasis. Finally, bioinformatics based miRNA-disease network analysis (MDN along with extended computational network analysis of Nrf2 associated pathologic processes suggests that if in a particular cellular scenario where any of these miR153/miR27a/miR142-5p/miR144 either individually or as a group is altered, it could affect Nrf2 thus triggering and

  10. Regulation of p53 by reversible post-transcriptional and post-translational mechanisms in liver and skeletal muscle of an anoxia tolerant turtle, Trachemys scripta elegans.

    Science.gov (United States)

    Zhang, Jing; Biggar, Kyle K; Storey, Kenneth B

    2013-01-15

    The red-eared slider turtle (Trachemys scripta elegans) exhibits well-developed natural anoxia tolerance that depends on multiple biochemical adaptations, including anoxia-induced hypometabolism. We hypothesized that signaling by the p53 protein could aid in establishing the hypometabolic state by arresting the cell cycle, protecting against DNA damage as well as altering pathways of energy metabolism. Immunoblotting was used to evaluate the regulation and post-transcriptional modifications of p53 in liver and skeletal muscle of red-eared slider turtles subjected to 5h or 20h of anoxic submergence. Tissue specific regulation of p53 was observed with the liver showing a more rapid activation of p53 in response to anoxia as well as differential expression of seven serine phosphorylation and two lysine acetylation sites when compared with skeletal muscle. Protein expression of MDM2, a major p53 inhibitor, was also examined but did not change during anoxia. Reverse-transcriptase PCR was used to assess transcript levels of selected p53 target genes (14-3-3σ, Gadd45α and Pgm) and one microRNA (miR-34a); results showed down-regulation of Pgm and up-regulation of the other three. These findings show an activation of p53 in response to anoxia exposure and suggest an important role for the p53 stress response pathway in regulating natural anoxia tolerance and hypometabolism in a vertebrate facultative anaerobe. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Constitutive expression of a putative high-affinity nitrate transporter in Nicotiana plumbaginifolia: evidence for post-transcriptional regulation by a reduced nitrogen source.

    Science.gov (United States)

    Fraisier, V; Gojon, A; Tillard, P; Daniel-Vedele, F

    2000-08-01

    The NpNRT2.1 gene encodes a putative inducible component of the high-affinity nitrate (NO3-) uptake system in Nicotiana plumbaginifolia. Here we report functional and physiological analyses of transgenic plants expressing the NpNRT2.1 coding sequence fused to the CaMV 35S or rolD promoters. Irrespective of the level of NO3- supplied, NO3- contents were found to be remarkably similar in wild-type and transgenic plants. Under specific conditions (growth on 10 mM NO3-), the steady-state NpNRT2. 1 mRNA level resulting from the deregulated transgene expression was accompanied by an increase in 15NO3- influx measured in the low concentration range. This demonstrates for the first time that the NRT2.1 sequence codes a limiting element of the inducible high-affinity transport system. Both 15NO3- influx and mRNA levels decreased in the wild type after exposure to ammonium, in agreement with previous results from many species. Surprisingly, however, influx was also markedly decreased in transgenic plants, despite stable levels of transgene expression in independent transformants after ammonium addition. We conclude that the conditions associated with the supply of a reduced nitrogen source such as ammonium, or with the generation of a further downstream metabolite, probably exert a repressive effect on NO3- influx at both transcriptional and post-transcriptional levels.

  12. A conserved RNA structural element within the hepatitis B virus post-transcriptional regulatory element enhance nuclear export of intronless transcripts and repress the splicing mechanism.

    Science.gov (United States)

    Visootsat, Akasit; Payungporn, Sunchai; T-Thienprasert, Nattanan P

    2015-12-01

    Hepatitis B virus (HBV) infection is a primary cause of hepatocellular carcinoma and liver cirrhosis worldwide. To develop novel antiviral drugs, a better understanding of HBV gene expression regulation is vital. One important aspect is to understand how HBV hijacks the cellular machinery to export unspliced RNA from the nucleus. The HBV post-transcriptional regulatory element (HBV PRE) has been proposed to be the HBV RNA nuclear export element. However, the function remains controversial, and the core element is unclear. This study, therefore, aimed to identify functional regulatory elements within the HBV PRE and investigate their functions. Using bioinformatics programs based on sequence conservation and conserved RNA secondary structures, three regulatory elements were predicted, namely PRE 1151-1410, PRE 1520-1620 and PRE 1650-1684. PRE 1151-1410 significantly increased intronless and unspliced luciferase activity in both HepG2 and COS-7 cells. Likewise, PRE 1151-1410 significantly elevated intronless and unspliced HBV surface transcripts in liver cancer cells. Moreover, motif analysis predicted that PRE 1151-1410 contains several regulatory motifs. This study reported the roles of PRE 1151-1410 in intronless transcript nuclear export and the splicing mechanism. Additionally, these results provide knowledge in the field of HBV RNA regulation. Moreover, PRE 1151-1410 may be used to enhance the expression of other mRNAs in intronless reporter plasmids.

  13. Post-transcriptional gene expression control by NANOS is up-regulated and functionally important in pRb-deficient cells.

    Science.gov (United States)

    Miles, Wayne O; Korenjak, Michael; Griffiths, Lyra M; Dyer, Michael A; Provero, Paolo; Dyson, Nicholas J

    2014-10-01

    Inactivation of the retinoblastoma tumor suppressor (pRb) is a common oncogenic event that alters the expression of genes important for cell cycle progression, senescence, and apoptosis. However, in many contexts, the properties of pRb-deficient cells are similar to wild-type cells suggesting there may be processes that counterbalance the transcriptional changes associated with pRb inactivation. Therefore, we have looked for sets of evolutionary conserved, functionally related genes that are direct targets of pRb/E2F proteins. We show that the expression of NANOS, a key facilitator of the Pumilio (PUM) post-transcriptional repressor complex, is directly repressed by pRb/E2F in flies and humans. In both species, NANOS expression increases following inactivation of pRb/RBF1 and becomes important for tissue homeostasis. By analyzing datasets from normal retinal tissue and pRb-null retinoblastomas, we find a strong enrichment for putative PUM substrates among genes de-regulated in tumors. These include pro-apoptotic genes that are transcriptionally down-regulated upon pRb loss, and we characterize two such candidates, MAP2K3 and MAP3K1, as direct PUM substrates. Our data suggest that NANOS increases in importance in pRb-deficient cells and helps to maintain homeostasis by repressing the translation of transcripts containing PUM Regulatory Elements (PRE). © 2014 The Authors.

  14. Opposing Post-transcriptional Control of InR by FMRP and LIN-28 Adjusts Stem Cell-Based Tissue Growth

    Directory of Open Access Journals (Sweden)

    Arthur Luhur

    2017-12-01

    Full Text Available Summary: Although the intrinsic mechanisms that control whether stem cells divide symmetrically or asymmetrically underlie tissue growth and homeostasis, they remain poorly defined. We report that the RNA-binding protein fragile X mental retardation protein (FMRP limits the symmetric division, and resulting expansion, of the stem cell population during adaptive intestinal growth in Drosophila. The elevated insulin sensitivity that FMRP-deficient progenitor cells display contributes to their accelerated expansion, which is suppressed by the depletion of insulin-signaling components. This FMRP activity is mediated solely via a second conserved RNA-binding protein, LIN-28, known to boost insulin signaling in stem cells. Via LIN-28, FMRP controls progenitor cell behavior by post-transcriptionally repressing the level of insulin receptor (InR. This study identifies the stem cell-based mechanism by which FMRP controls tissue adaptation, and it raises the possibility that defective adaptive growth underlies the accelerated growth, gastrointestinal, and other symptoms that affect fragile X syndrome patients. : Luhur et al. report that FMRP acts via LIN-28 in progenitor cells to dampen the adaptive expansion of intestinal tissue in the fruit fly, raising the possibility that defective LIN28-mediated adaptive growth underlies some of the symptoms that affect fragile X syndrome patients. Keywords: FMRP, fmr1, LIN-28, insulin receptor, IIS, adaptive growth, tissue resizing, intestinal stem cell, insulin sensitivity

  15. Bone regeneration in critical bone defects using three-dimensionally printed β-tricalcium phosphate/hydroxyapatite scaffolds is enhanced by coating scaffolds with either dipyridamole or BMP-2.

    Science.gov (United States)

    Ishack, Stephanie; Mediero, Aranzazu; Wilder, Tuere; Ricci, John L; Cronstein, Bruce N

    2017-02-01

    Bone defects resulting from trauma or infection need timely and effective treatments to restore damaged bone. Using specialized three-dimensional (3D) printing technology we have created custom 3D scaffolds of hydroxyapatite (HA)/beta-tri-calcium phosphate (β-TCP) to promote bone repair. To further enhance bone regeneration we have coated the scaffolds with dipyridamole, an agent that increases local adenosine levels by blocking cellular uptake of adenosine. Nearly 15% HA:85% β-TCP scaffolds were designed using Robocad software, fabricated using a 3D Robocasting system, and sintered at 1100°C for 4 h. Scaffolds were coated with BMP-2 (200 ng mL -1 ), dypiridamole 100 µM or saline and implanted in C57B6 and adenosine A2A receptor knockout (A2AKO) mice with 3 mm cranial critical bone defects for 2-8 weeks. Dipyridamole release from scaffold was assayed spectrophotometrically. MicroCT and histological analysis were performed. Micro-computed tomography (microCT) showed significant bone formation and remodeling in HA/β-TCP-dipyridamole and HA/β-TCP-BMP-2 scaffolds when compared to scaffolds immersed in vehicle at 2, 4, and 8 weeks (n = 5 per group; p ≤ 0.05, p ≤ 0.05, and p ≤ 0.01, respectively). Histological analysis showed increased bone formation and a trend toward increased remodeling in HA/β-TCP- dipyridamole and HA/β-TCP-BMP-2 scaffolds. Coating scaffolds with dipyridamole did not enhance bone regeneration in A2AKO mice. In conclusion, scaffolds printed with HA/β-TCP promote bone regeneration in critical bone defects and coating these scaffolds with agents that stimulate A2A receptors and growth factors can further enhance bone regeneration. These coated scaffolds may be very useful for treating critical bone defects due to trauma, infection or other causes. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 366-375, 2017. © 2015 Wiley Periodicals, Inc.

  16. Autologous serum improves bone formation in a primary stable silica-embedded nanohydroxyapatite bone substitute in combination with mesenchymal stem cells and rhBMP-2 in the sheep model

    Directory of Open Access Journals (Sweden)

    Boos AM

    2014-11-01

    Full Text Available Anja M Boos,1,* Annika Weigand,1,* Gloria Deschler,1 Thomas Gerber,2 Andreas Arkudas,1 Ulrich Kneser,1 Raymund E Horch,1 Justus P Beier11Department of Plastic and Hand Surgery, University Hospital of Erlangen, Friedrich-Alexander-University of Erlangen-Nürnberg FAU, Erlangen, 2Institute of Physics, University of Rostock, Rostock, Germany *These authors contributed equally to this work Abstract: New therapeutic strategies are required for critical size bone defects, because the gold standard of transplanting autologous bone from an unharmed area of the body often leads to several severe side effects and disadvantages for the patient. For years, tissue engineering approaches have been seeking a stable, axially vascularized transplantable bone replacement suitable for transplantation into the recipient bed with pre-existing insufficient conditions. For this reason, the arteriovenous loop model was developed and various bone substitutes have been vascularized. However, it has not been possible thus far to engineer a primary stable and axially vascularized transplantable bone substitute. For that purpose, a primary stable silica-embedded nanohydroxyapatite (HA bone substitute in combination with blood, bone marrow, expanded, or directly retransplanted mesenchymal stem cells, recombinant human bone morphogenetic protein 2 (rhBMP-2, and different carrier materials (fibrin, cell culture medium, autologous serum was tested subcutaneously for 4 or 12 weeks in the sheep model. Autologous serum lead to an early matrix change during degradation of the bone substitute and formation of new bone tissue. The best results were achieved in the group combining mesenchymal stem cells expanded with 60 µg/mL rhBMP-2 in autologous serum. Better ingrowth of fibrovascular tissue could be detected in the autologous serum group compared with the control (fibrin. Osteoclastic activity indicating an active bone remodeling process was observed after 4 weeks, particularly

  17. Characterization and use of Equine Bone Marrow Mesenchymal Stem Cells in Equine Cartilage Engineering. Study of their Hyaline Cartilage Forming Potential when Cultured under Hypoxia within a Biomaterial in the Presence of BMP-2 and TGF-ß1.

    Science.gov (United States)

    Branly, Thomas; Bertoni, Lélia; Contentin, Romain; Rakic, Rodolphe; Gomez-Leduc, Tangni; Desancé, Mélanie; Hervieu, Magalie; Legendre, Florence; Jacquet, Sandrine; Audigié, Fabrice; Denoix, Jean-Marie; Demoor, Magali; Galéra, Philippe

    2017-10-01

    Articular cartilage presents a poor capacity for self-repair. Its structure-function are frequently disrupted or damaged upon physical trauma or osteoarthritis in humans. Similar musculoskeletal disorders also affect horses and are the leading cause of poor performance or early retirement of sport- and racehorses. To develop a therapeutic solution for horses, we tested the autologous chondrocyte implantation technique developed on human bone marrow (BM) mesenchymal stem cells (MSCs) on horse BM-MSCs. This technique involves BM-MSC chondrogenesis using a combinatory approach based on the association of 3D-culture in collagen sponges, under hypoxia in the presence of chondrogenic factors (BMP-2 + TGF-β 1 ) and siRNA to knockdown collagen I and HtrA1. Horse BM-MSCs were characterized before being cultured in chondrogenic conditions to find the best combination to enhance, stabilize, the chondrocyte phenotype. Our results show a very high proliferation of MSCs and these cells satisfy the criteria defining stem cells (pluripotency-surface markers expression). The combination of BMP-2 + TGF-β 1 strongly induces the chondrogenic differentiation of MSCs and prevents HtrA1 expression. siRNAs targeting Col1a1 and Htra1 were functionally validated. Ultimately, the combined use of specific culture conditions defined here with specific growth factors and a Col1a1 siRNAs (50 nM) association leads to the in vitro synthesis of a hyaline-type neocartilage whose chondrocytes present an optimal phenotypic index similar to that of healthy, differentiated chondrocytes. Our results lead the way to setting up pre-clinical trials in horses to better understand the reaction of neocartilage substitute and to carry out a proof-of-concept of this therapeutic strategy on a large animal model.

  18. 17beta-estradiol induced vitellogenesis is inhibited by cortisol at the post-transcriptional level in Arctic char (Salvelinus alpinus

    Directory of Open Access Journals (Sweden)

    Modig Carina

    2004-09-01

    Full Text Available Abstract This study was performed to investigate stress effects on the synthesis of egg yolk precursor, vitellogenin (Vtg in Arctic char (Salvelinus alpinus. In particular the effect of cortisol (F was determined since this stress hormone has been suggested to interfere with vitellogenesis and is upregulated during sexual maturation in teleosts. Arctic char Vtg was purified and polyclonal antibodies were produced in order to develop tools to study regulation of vitellogenesis. The Vtg antibodies were used to develop an enzyme-linked immunosorbent assay. The corresponding Vtg cDNA was cloned from a hepatic cDNA library in order to obtain DNA probes to measure Vtg mRNA expression. Analysis of plasma from juvenile Arctic char, of both sexes, exposed to different steroids showed that production of Vtg was induced in a dose dependent fashion by 17β-estradiol (E2, estrone and estriol. Apart from estrogens a high dose of F also upregulated Vtg. In addition, F, progesterone (P and tamoxifen were tested to determine these compounds ability to modulate E2 induced Vtg synthesis at both the mRNA and protein level. Tamoxifen was found to inhibit E2 induced Vtg mRNA and protein upregulation. P did not alter the Vtg induction while F reduced the Vtg protein levels without affecting the Vtg mRNA levels. Furthermore the inhibition of Vtg protein was found to be dose dependent. Thus, the inhibitory effect of F on Vtg appears to be mediated at the post-transcriptional level.

  19. Rift Valley fever virus NSs protein promotes post-transcriptional downregulation of protein kinase PKR and inhibits eIF2alpha phosphorylation.

    Science.gov (United States)

    Ikegami, Tetsuro; Narayanan, Krishna; Won, Sungyong; Kamitani, Wataru; Peters, C J; Makino, Shinji

    2009-02-01

    Rift Valley fever virus (RVFV) (genus Phlebovirus, family Bunyaviridae) is a negative-stranded RNA virus with a tripartite genome. RVFV is transmitted by mosquitoes and causes fever and severe hemorrhagic illness among humans, and fever and high rates of abortions in livestock. A nonstructural RVFV NSs protein inhibits the transcription of host mRNAs, including interferon-beta mRNA, and is a major virulence factor. The present study explored a novel function of the RVFV NSs protein by testing the replication of RVFV lacking the NSs gene in the presence of actinomycin D (ActD) or alpha-amanitin, both of which served as a surrogate of the host mRNA synthesis suppression function of the NSs. In the presence of the host-transcriptional inhibitors, the replication of RVFV lacking the NSs protein, but not that carrying NSs, induced double-stranded RNA-dependent protein kinase (PKR)-mediated eukaryotic initiation factor (eIF)2alpha phosphorylation, leading to the suppression of host and viral protein translation. RVFV NSs promoted post-transcriptional downregulation of PKR early in the course of the infection and suppressed the phosphorylated eIF2alpha accumulation. These data suggested that a combination of RVFV replication and NSs-induced host transcriptional suppression induces PKR-mediated eIF2alpha phosphorylation, while the NSs facilitates efficient viral translation by downregulating PKR and inhibiting PKR-mediated eIF2alpha phosphorylation. Thus, the two distinct functions of the NSs, i.e., the suppression of host transcription, including that of type I interferon mRNAs, and the downregulation of PKR, work together to prevent host innate antiviral functions, allowing efficient replication and survival of RVFV in infected mammalian hosts.

  20. Rift Valley fever virus NSs protein promotes post-transcriptional downregulation of protein kinase PKR and inhibits eIF2alpha phosphorylation.

    Directory of Open Access Journals (Sweden)

    Tetsuro Ikegami

    2009-02-01

    Full Text Available Rift Valley fever virus (RVFV (genus Phlebovirus, family Bunyaviridae is a negative-stranded RNA virus with a tripartite genome. RVFV is transmitted by mosquitoes and causes fever and severe hemorrhagic illness among humans, and fever and high rates of abortions in livestock. A nonstructural RVFV NSs protein inhibits the transcription of host mRNAs, including interferon-beta mRNA, and is a major virulence factor. The present study explored a novel function of the RVFV NSs protein by testing the replication of RVFV lacking the NSs gene in the presence of actinomycin D (ActD or alpha-amanitin, both of which served as a surrogate of the host mRNA synthesis suppression function of the NSs. In the presence of the host-transcriptional inhibitors, the replication of RVFV lacking the NSs protein, but not that carrying NSs, induced double-stranded RNA-dependent protein kinase (PKR-mediated eukaryotic initiation factor (eIF2alpha phosphorylation, leading to the suppression of host and viral protein translation. RVFV NSs promoted post-transcriptional downregulation of PKR early in the course of the infection and suppressed the phosphorylated eIF2alpha accumulation. These data suggested that a combination of RVFV replication and NSs-induced host transcriptional suppression induces PKR-mediated eIF2alpha phosphorylation, while the NSs facilitates efficient viral translation by downregulating PKR and inhibiting PKR-mediated eIF2alpha phosphorylation. Thus, the two distinct functions of the NSs, i.e., the suppression of host transcription, including that of type I interferon mRNAs, and the downregulation of PKR, work together to prevent host innate antiviral functions, allowing efficient replication and survival of RVFV in infected mammalian hosts.

  1. MicroRNA-20a/b regulates cholesterol efflux through post-transcriptional repression of ATP-binding cassette transporter A1.

    Science.gov (United States)

    Liang, Bin; Wang, Xin; Song, Xiaosu; Bai, Rui; Yang, Huiyu; Yang, Zhiming; Xiao, Chuanshi; Bian, Yunfei

    2017-09-01

    ATP-binding cassette transporter A1 (ABCA1) plays a crucial role in reverse cholesterol transport and exhibits anti-atherosclerosis effects. Some microRNAs (miRs) regulate ABCA1 expression, and recent studies have shown that miR-20a/b might play a critical role in atherosclerotic diseases. Here, we attempted to clarify the potential contribution of miR-20a/b in post-transcriptional regulation of ABCA1, cholesterol efflux, and atherosclerosis. We performed bioinformatics analysis and found that miR-20a/b was highly conserved and directly bound to ABCA1 mRNA with low binding free energy. Luciferase-reporter assay also confirmed that miR-20a/b significantly reduced luciferase activity associated with the ABCA1 3' untranslated region reporter construct. Additionally, miR-20a/b decreased ABCA1 expression, which, in turn, decreased cholesterol efflux and increased cholesterol content in THP-1 and RAW 264.7 macrophage-derived foam cells. In contrast, miR-20a/b inhibitors increased ABCA1 expression and cholesterol efflux, decreased cholesterol content, and inhibited foam-cell formation. Consistent with our in vitro results, miR-20a/b-treated ApoE -/- mice showed decreased ABCA1expression in the liver and reductions of reverse cholesterol transport in vivo. Furthermore, miR-20a/b regulated the formation of nascent high-density lipoprotein and promoted atherosclerotic development, whereas miR-20a/b knockdown attenuated atherosclerotic formation. miR-20 is a new miRNA capable of targeting ABCA1 and regulating ABCA1 expression. Therefore, miR-20 inhibition constitutes a new strategy for ABCA1-based treatment of atherosclerosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Transient Co-Expression of Post-Transcriptional Gene Silencing Suppressors for Increased in Planta Expression of a Recombinant Anthrax Receptor Fusion Protein

    Directory of Open Access Journals (Sweden)

    Kittipong Rattanaporn

    2011-08-01

    Full Text Available Potential epidemics of infectious diseases and the constant threat of bioterrorism demand rapid, scalable, and cost-efficient manufacturing of therapeutic proteins. Molecular farming of tobacco plants provides an alternative for the recombinant production of therapeutics. We have developed a transient production platform that uses Agrobacterium infiltration of Nicotiana benthamiana plants to express a novel anthrax receptor decoy protein (immunoadhesin, CMG2-Fc. This chimeric fusion protein, designed to protect against the deadly anthrax toxins, is composed of the von Willebrand factor A (VWA domain of human capillary morphogenesis 2 (CMG2, an effective anthrax toxin receptor, and the Fc region of human immunoglobulin G (IgG. We evaluated, in N. benthamiana intact plants and detached leaves, the expression of CMG2-Fc under the control of the constitutive CaMV 35S promoter, and the co-expression of CMG2-Fc with nine different viral suppressors of post-transcriptional gene silencing (PTGS: p1, p10, p19, p21, p24, p25, p38, 2b, and HCPro. Overall, transient CMG2-Fc expression was higher on intact plants than detached leaves. Maximum expression was observed with p1 co-expression at 3.5 days post-infiltration (DPI, with a level of 0.56 g CMG2-Fc per kg of leaf fresh weight and 1.5% of the total soluble protein, a ten-fold increase in expression when compared to absence of suppression. Co-expression with the p25 PTGS suppressor also significantly increased the CMG2-Fc expression level after just 3.5 DPI.

  3. Transient co-expression of post-transcriptional gene silencing suppressors for increased in planta expression of a recombinant anthrax receptor fusion protein.

    Science.gov (United States)

    Arzola, Lucas; Chen, Junxing; Rattanaporn, Kittipong; Maclean, James M; McDonald, Karen A

    2011-01-01

    Potential epidemics of infectious diseases and the constant threat of bioterrorism demand rapid, scalable, and cost-efficient manufacturing of therapeutic proteins. Molecular farming of tobacco plants provides an alternative for the recombinant production of therapeutics. We have developed a transient production platform that uses Agrobacterium infiltration of Nicotiana benthamiana plants to express a novel anthrax receptor decoy protein (immunoadhesin), CMG2-Fc. This chimeric fusion protein, designed to protect against the deadly anthrax toxins, is composed of the von Willebrand factor A (VWA) domain of human capillary morphogenesis 2 (CMG2), an effective anthrax toxin receptor, and the Fc region of human immunoglobulin G (IgG). We evaluated, in N. benthamiana intact plants and detached leaves, the expression of CMG2-Fc under the control of the constitutive CaMV 35S promoter, and the co-expression of CMG2-Fc with nine different viral suppressors of post-transcriptional gene silencing (PTGS): p1, p10, p19, p21, p24, p25, p38, 2b, and HCPro. Overall, transient CMG2-Fc expression was higher on intact plants than detached leaves. Maximum expression was observed with p1 co-expression at 3.5 days post-infiltration (DPI), with a level of 0.56 g CMG2-Fc per kg of leaf fresh weight and 1.5% of the total soluble protein, a ten-fold increase in expression when compared to absence of suppression. Co-expression with the p25 PTGS suppressor also significantly increased the CMG2-Fc expression level after just 3.5 DPI.

  4. HuB (elavl2 mRNA is restricted to the germ cells by post-transcriptional mechanisms including stabilisation of the message by DAZL.

    Directory of Open Access Journals (Sweden)

    Sophie E Wiszniak

    Full Text Available The ability of germ cells to carry out a gene regulatory program distinct from the surrounding somatic tissue, and their capacity to specify an entire new organism has made them a focus of many studies that seek to understand how specific regulatory mechanisms, particularly post-transcriptional mechanisms, contribute to cell fate. In zebrafish, germ cells are specified through the inheritance of cytoplasmic determinants, termed the germ plasm, which contains a number of maternal mRNAs and proteins. Investigation of several of these messages has revealed that the restricted localisation of these mRNAs to the germ plasm and subsequent germ cells is due to cis-acting sequence elements present in their 3'UTRs. Here we show that a member of the Hu family of RNA-binding proteins, HuB, is maternally provided in the zebrafish embryo and exhibits germ cell specific expression during embryogenesis. Restriction of HuB mRNA to the germ cells is dependent on a number of sequence elements in its 3'UTR, which act to degrade the mRNA in the soma and stabilise it in the germ cells. In addition, we show that the germ cell specific RNA-binding protein DAZL is able to promote HuB mRNA stability and translation in germ cells, and further demonstrate that these activities require a 30 nucleotide element in the 3'UTR. Our study suggests that DAZL specifically binds the HuB 3'UTR and protects the message from degradation and/or enhances HuB translation, leading to the germ cell specific expression of HuB protein.

  5. Inhibition of Mef2a Enhances Neovascularization via Post-transcriptional Regulation of 14q32 MicroRNAs miR-329 and miR-494

    Directory of Open Access Journals (Sweden)

    Sabine M.J. Welten

    2017-06-01

    Full Text Available Improving the efficacy of neovascularization is a promising strategy to restore perfusion of ischemic tissues in patients with peripheral arterial disease. The 14q32 microRNA cluster is highly involved in neovascularization. The Mef2a transcription factor has been shown to induce transcription of the microRNAs within this cluster. We inhibited expression of Mef2a using gene-silencing oligonucleotides (GSOs in an in vivo hind limb ischemia model. Treatment with GSO-Mef2a clearly improved blood flow recovery within 3 days (44% recovery versus 25% recovery in control and persisted until 14 days after ischemia induction (80% recovery versus 60% recovery in control. Animals treated with GSO-Mef2a showed increased arteriogenesis and angiogenesis in the relevant muscle tissues. Inhibition of Mef2a decreased expression of 14q32 microRNAs miR-329 (p = 0.026 and miR-494 (trend, p = 0.06, but not of other 14q32 microRNAs, nor of 14q32 microRNA precursors. Because Mef2a did not influence 14q32 microRNA transcription, we hypothesized it functions as an RNA-binding protein that influences processing of 14q32 microRNA miR-329 and miR-494. Mef2A immunoprecipitation followed by RNA isolation and rt/qPCR confirmed direct binding of MEF2A to pri-miR-494, supporting this hypothesis. Our study demonstrates a novel function for Mef2a in post-ischemic neovascularization via post-transcriptional regulation of 14q32 microRNAs miR-329 and miR-494.

  6. The Polycistronic miR166k-166h Positively Regulates Rice Immunity via Post-transcriptional Control of EIN2

    Directory of Open Access Journals (Sweden)

    Raquel Salvador-Guirao

    2018-03-01

    Full Text Available MicroRNAs (miRNAs are small RNAs acting as regulators of gene expression at the post-transcriptional level. In plants, most miRNAs are generated from independent transcriptional units, and only a few polycistronic miRNAs have been described. miR166 is a conserved miRNA in plants targeting the HD-ZIP III transcription factor genes. Here, we show that a polycistronic miRNA comprising two miR166 family members, miR166k and miR166h, functions as a positive regulator of rice immunity. Rice plants with activated MIR166k-166h expression showed enhanced resistance to infection by the fungal pathogens Magnaporthe oryzae and Fusarium fujikuroi, the causal agents of the rice blast and bakanae disease, respectively. Disease resistance in rice plants with activated MIR166k-166h expression was associated with a stronger expression of defense responses during pathogen infection. Stronger induction of MIR166k-166h expression occurred in resistant but not susceptible rice cultivars. Notably, the ethylene-insensitive 2 (EIN2 gene was identified as a novel target gene for miR166k. The regulatory role of the miR166h-166k polycistron on the newly identified target gene results from the activity of the miR166k-5p specie generated from the miR166k-166h precursor. Collectively, our findings support a role for miR166k-5p in rice immunity by controlling EIN2 expression. Because rice blast is one of the most destructive diseases of cultivated rice worldwide, unraveling miR166k-166h-mediated mechanisms underlying blast resistance could ultimately help in designing appropriate strategies for rice protection.

  7. Hepatitis B virus nuclear export elements: RNA stem-loop α and β, key parts of the HBV post-transcriptional regulatory element.

    Science.gov (United States)

    Lim, Chun Shen; Brown, Chris M

    2016-09-01

    Many viruses contain RNA elements that modulate splicing and/or promote nuclear export of their RNAs. The RNAs of the major human pathogen, hepatitis B virus (HBV) contain a large (~600 bases) composite cis-acting 'post-transcriptional regulatory element' (PRE). This element promotes expression from these naturally intronless transcripts. Indeed, the related woodchuck hepadnavirus PRE (WPRE) is used to enhance expression in gene therapy and other expression vectors. These PRE are likely to act through a combination of mechanisms, including promotion of RNA nuclear export. Functional components of both the HBV PRE and WPRE are 2 conserved RNA cis-acting stem-loop (SL) structures, SLα and SLβ. They are within the coding regions of polymerase (P) gene, and both P and X genes, respectively. Based on previous studies using mutagenesis and/or nuclear magnetic resonance (NMR), here we propose 2 covariance models for SLα and SLβ. The model for the 30-nucleotide SLα contains a G-bulge and a CNGG(U) apical loop of which the first and the fourth loop residues form a CG pair and the fifth loop residue is bulged out, as observed in the NMR structure. The model for the 23-nucleotide SLβ contains a 7-base-pair stem and a 9-nucleotide loop. Comparison of the models with other RNA structural elements, as well as similarity searches of human transcriptome and viral genomes demonstrate that SLα and SLβ are specific to HBV transcripts. However, they are well conserved among the hepadnaviruses of non-human primates, the woodchuck and ground squirrel.

  8. Switching Phenomena

    Science.gov (United States)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Mazza, M. G.; Kumar, P.; Plerou, V.; Preis, T.; Stokely, K.; Xu, L.

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines can suddenly "switch" from one behavior to another, even though they possess no perfect metronome in time. As if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many temporal patterns in physics, economics, and medicine and even begin to characterize the switching phenomena that enable a system to pass from one state to another. We discuss some applications of correlated randomness to understanding switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water's anomalies are related to a switching point (which is not unlike the "tipping point" immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not "outliers" (another Gladwell immortalization).

  9. Time-sequential changes of differentially expressed miRNAs during the process of anterior lumbar interbody fusion using equine bone protein extract, rhBMP-2 and autograft

    Science.gov (United States)

    Chen, Da-Fu; Zhou, Zhi-Yu; Dai, Xue-Jun; Gao, Man-Man; Huang, Bao-Ding; Liang, Tang-Zhao; Shi, Rui; Zou, Li-Jin; Li, Hai-Sheng; Bünger, Cody; Tian, Wei; Zou, Xue-Nong

    2014-03-01

    The precise mechanism of bone regeneration in different bone graft substitutes has been well studied in recent researches. However, miRNAs regulation of the bone formation has been always mysterious. We developed the anterior lumbar interbody fusion (ALIF) model in pigs using equine bone protein extract (BPE), recombinant human bone morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS), and autograft as bone graft substitute, respectively. The miRNA and gene expression profiles of different bone graft materials were examined using microarray technology and data analysis, including self-organizing maps, KEGG pathway and Biological process GO analyses. We then jointly analyzed miRNA and mRNA profiles of the bone fusion tissue at different time points respectively. Results showed that miRNAs, including let-7, miR-129, miR-21, miR-133, miR-140, miR-146, miR-184, and miR-224, were involved in the regulation of the immune and inflammation response, which provided suitable inflammatory microenvironment for bone formation. At late stage, several miRNAs directly regulate SMAD4, Estrogen receptor 1 and 5-hydroxytryptamine (serotonin) receptor 2C for bone formation. It can be concluded that miRNAs play important roles in balancing the inflammation and bone formation.

  10. Macrolactin F inhibits RANKL-mediated osteoclastogenesis by suppressing Akt, MAPK and NFATc1 pathways and promotes osteoblastogenesis through a BMP-2/smad/Akt/Runx2 signaling pathway.

    Science.gov (United States)

    Li, Liang; Sapkota, Mahesh; Gao, Ming; Choi, Hyukjae; Soh, Yunjo

    2017-11-15

    The balance between bone formation and bone resorption is maintained by osteoblasts and osteoclasts. In the current study, macrolactin F (MF) was investigated for novel biological activity on the receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis in primary bone marrow-derived macrophages (BMMs). We found that RANKL-induced osteoclast formation and differentiation from BMMs was significantly inhibited by MF in a dose-dependent manner without cytotoxicity. RANKL-induced F-actin ring formation and bone resorption activity in BMMs which was attenuated by MF. In addition, MF suppressed the expression of osteoclast-related genes, including c-myc, RANK, tartrate-resistant acid phosphatase (TRAP), nuclear factor of activated T cells c1 (NFATc1), cathepsin K and matrix metalloproteinase 9 (MMP9). Furthermore, the protein expression NFATc1, c-Fos, MMP9, cathepsin K and phosphorylation of Jun N-terminal kinase (JNK), p38 and Akt were also down-regulated by MF treatment. Interestingly, MF promoted pre-osteoblast cell differentiation on Alizarin Red-mineralization activity, alkaline phosphatase (ALP) activity, and the expression of osteoblastogenic markers including Runx2, Osterix, Smad4, ALP, type I collagen alpha 1 (Col1α), osteopontin (OPN), and osteocalcin (OCN) via activation of the BMP-2/smad/Akt/Runx2 pathway on MC3T3-E1. Taken together, these results indicate that MF may be useful as a therapeutic agent to enhance bone health and treat osteoporosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Switched on!

    CERN Multimedia

    2008-01-01

    Like a star arriving on stage, impatiently followed by each member of CERN personnel and by millions of eyes around the world, the first beam of protons has circulated in the LHC. After years in the making and months of increasing anticipation, today the work of hundreds of people has borne fruit. WELL DONE to all! Successfully steered around the 27 kilometres of the world’s most powerful particle accelerator at 10:28 this morning, this first beam of protons circulating in the ring marks a key moment in the transition from over two decades of preparation to a new era of scientific discovery. "It’s a fantastic moment," said the LHC project leader Lyn Evans, "we can now look forward to a new era of understanding about the origins and evolution of the universe". Starting up a major new particle accelerator takes much more than flipping a switch. Thousands of individual elements have to work in harmony, timings have to be synchronize...

  12. Mycobacterial RNA isolation optimized for non-coding RNA: high fidelity isolation of 5S rRNA from Mycobacterium bovis BCG reveals novel post-transcriptional processing and a complete spectrum of modified ribonucleosides.

    Science.gov (United States)

    Hia, Fabian; Chionh, Yok Hian; Pang, Yan Ling Joy; DeMott, Michael S; McBee, Megan E; Dedon, Peter C

    2015-03-11

    A major challenge in the study of mycobacterial RNA biology is the lack of a comprehensive RNA isolation method that overcomes the unusual cell wall to faithfully yield the full spectrum of non-coding RNA (ncRNA) species. Here, we describe a simple and robust procedure optimized for the isolation of total ncRNA, including 5S, 16S and 23S ribosomal RNA (rRNA) and tRNA, from mycobacteria, using Mycobacterium bovis BCG to illustrate the method. Based on a combination of mechanical disruption and liquid and solid-phase technologies, the method produces all major species of ncRNA in high yield and with high integrity, enabling direct chemical and sequence analysis of the ncRNA species. The reproducibility of the method with BCG was evident in bioanalyzer electrophoretic analysis of isolated RNA, which revealed quantitatively significant differences in the ncRNA profiles of exponentially growing and non-replicating hypoxic bacilli. The method also overcame an historical inconsistency in 5S rRNA isolation, with direct sequencing revealing a novel post-transcriptional processing of 5S rRNA to its functional form and with chemical analysis revealing seven post-transcriptional ribonucleoside modifications in the 5S rRNA. This optimized RNA isolation procedure thus provides a means to more rigorously explore the biology of ncRNA species in mycobacteria. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  13. 3-(3-amino-3-carboxypropyl)-5,6-Dihydrouridine is one of two novel post-transcriptional modifications in tRNALys(UUU) from Trypanosoma brucei

    DEFF Research Database (Denmark)

    Krog, Jesper Schak; Español, Yaiza; Giessing, Anders M B

    2011-01-01

    tRNA is the most heavily modified of all RNA types, with typically 10-20% of the residues being post-transcriptionally altered. Unravelling the modification pattern of a tRNA is a challenging task; there are 92 currently known tRNA modifications [1], many of which are chemically similar. Furtherm......tRNA is the most heavily modified of all RNA types, with typically 10-20% of the residues being post-transcriptionally altered. Unravelling the modification pattern of a tRNA is a challenging task; there are 92 currently known tRNA modifications [1], many of which are chemically similar...... of the unmodified tRNA revealed the modified residues. The modifications were further characterized at the nucleoside level by chromatographic retention time and fragmentation pattern upon higher-order tandem MS. Phylogenetic comparison with modifications in tRNA(Lys) from other organisms was used through......: a minor fraction with the previously described 2-methylthio-N(6) -threonylcarbamoyl-modification, and a major fraction with A37 being modified by a 294.0-Da moiety. The latter product is the largest adenosine modification reported so far, and we discuss its nature and origin....

  14. Digital switched hydraulics

    Science.gov (United States)

    Pan, Min; Plummer, Andrew

    2018-06-01

    This paper reviews recent developments in digital switched hydraulics particularly the switched inertance hydraulic systems (SIHSs). The performance of SIHSs is presented in brief with a discussion of several possible configurations and control strategies. The soft switching technology and high-speed switching valve design techniques are discussed. Challenges and recommendations are given based on the current research achievements.

  15. Latching micro optical switch

    Science.gov (United States)

    Garcia, Ernest J; Polosky, Marc A

    2013-05-21

    An optical switch reliably maintains its on or off state even when subjected to environments where the switch is bumped or otherwise moved. In addition, the optical switch maintains its on or off state indefinitely without requiring external power. External power is used only to transition the switch from one state to the other. The optical switch is configured with a fixed optical fiber and a movable optical fiber. The movable optical fiber is guided by various actuators in conjunction with a latching mechanism that configure the switch in one position that corresponds to the on state and in another position that corresponds to the off state.

  16. The post-transcriptional regulator rsmA/csrA activates T3SS by stabilizing the 5' UTR of hrpG, the master regulator of hrp/hrc genes, in Xanthomonas.

    Directory of Open Access Journals (Sweden)

    Maxuel O Andrade

    2014-02-01

    Full Text Available The RsmA/CsrA family of the post-transcriptional regulators of bacteria is involved in the regulation of many cellular processes, including pathogenesis. In this study, we demonstrated that rsmA not only is required for the full virulence of the phytopathogenic bacterium Xanthomonas citri subsp. citri (XCC but also contributes to triggering the hypersensitive response (HR in non-host plants. Deletion of rsmA resulted in significantly reduced virulence in the host plant sweet orange and a delayed and weakened HR in the non-host plant Nicotiana benthamiana. Microarray, quantitative reverse-transcription PCR, western-blotting, and GUS assays indicated that RsmA regulates the expression of the type 3 secretion system (T3SS at both transcriptional and post-transcriptional levels. The regulation of T3SS by RsmA is a universal phenomenon in T3SS-containing bacteria, but the specific mechanism seems to depend on the interaction between a particular bacterium and its hosts. For Xanthomonads, the mechanism by which RsmA activates T3SS remains unknown. Here, we show that RsmA activates the expression of T3SS-encoding hrp/hrc genes by directly binding to the 5' untranslated region (UTR of hrpG, the master regulator of the hrp/hrc genes in XCC. RsmA stabilizes hrpG mRNA, leading to increased accumulation of HrpG proteins and subsequently, the activation of hrp/hrc genes. The activation of the hrp/hrc genes by RsmA via HrpG was further supported by the observation that ectopic overexpression of hrpG in an rsmA mutant restored its ability to cause disease in host plants and trigger HR in non-host plants. RsmA also stabilizes the transcripts of another T3SS-associated hrpD operon by directly binding to the 5' UTR region. Taken together, these data revealed that RsmA primarily activates T3SS by acting as a positive regulator of hrpG and that this regulation is critical to the pathogenicity of XCC.

  17. Integrated mRNA and microRNA analysis identifies genes and small miRNA molecules associated with transcriptional and post-transcriptional-level responses to both drought stress and re-watering treatment in tobacco.

    Science.gov (United States)

    Chen, Qiansi; Li, Meng; Zhang, Zhongchun; Tie, Weiwei; Chen, Xia; Jin, Lifeng; Zhai, Niu; Zheng, Qingxia; Zhang, Jianfeng; Wang, Ran; Xu, Guoyun; Zhang, Hui; Liu, Pingping; Zhou, Huina

    2017-01-10

    Drought stress is one of the most severe problem limited agricultural productivity worldwide. It has been reported that plants response to drought-stress by sophisticated mechanisms at both transcriptional and post-transcriptional levels. However, the precise molecular mechanisms governing the responses of tobacco leaves to drought stress and water status are not well understood. To identify genes and miRNAs involved in drought-stress responses in tobacco, we performed both mRNA and small RNA sequencing on tobacco leaf samples from the following three treatments: untreated-control (CL), drought stress (DL), and re-watering (WL). In total, we identified 798 differentially expressed genes (DEGs) between the DL and CL (DL vs. CL) treatments and identified 571 DEGs between the WL and DL (WL vs. DL) treatments. Further analysis revealed 443 overlapping DEGs between the DL vs. CL and WL vs. DL comparisons, and, strikingly, all of these genes exhibited opposing expression trends between these two comparisons, strongly suggesting that these overlapping DEGs are somehow involved in the responses of tobacco leaves to drought stress. Functional annotation analysis showed significant up-regulation of genes annotated to be involved in responses to stimulus and stress, (e.g., late embryogenesis abundant proteins and heat-shock proteins) antioxidant defense (e.g., peroxidases and glutathione S-transferases), down regulation of genes related to the cell cycle pathway, and photosynthesis processes. We also found 69 and 56 transcription factors (TFs) among the DEGs in, respectively, the DL vs. CL and the WL vs. DL comparisons. In addition, small RNA sequencing revealed 63 known microRNAs (miRNA) from 32 families and 368 novel miRNA candidates in tobacco. We also found that five known miRNA families (miR398, miR390, miR162, miR166, and miR168) showed differential regulation under drought conditions. Analysis to identify negative correlations between the differentially expressed mi

  18. Optical packet switched networks

    DEFF Research Database (Denmark)

    Hansen, Peter Bukhave

    1999-01-01

    Optical packet switched networks are investigated with emphasis on the performance of the packet switch blocks. Initially, the network context of the optical packet switched network is described showing that a packet network will provide transparency, flexibility and bridge the granularity gap...... in interferometric wavelength converters is investigated showing that a 10 Gbit/s 19 4x4 swich blocks can be cascaded at a BER of 10-14. An analytical traffic model enables the calculation of the traffice performance of a WDM packet network. Hereby the importance of WDM and wavelegth conversion in the switch blocks...... is established as a flexible means to reduce the optical buffer, e.g., the number of fibre delay lines for a 16x16 switch block is reduced from 23 to 6 by going from 2 to 8 wavelength channels pr. inlet. Additionally, a component count analysis is carried out to illustrate the trade-offs in the switch block...

  19. Saturated Switching Systems

    CERN Document Server

    Benzaouia, Abdellah

    2012-01-01

    Saturated Switching Systems treats the problem of actuator saturation, inherent in all dynamical systems by using two approaches: positive invariance in which the controller is designed to work within a region of non-saturating linear behaviour; and saturation technique which allows saturation but guarantees asymptotic stability. The results obtained are extended from the linear systems in which they were first developed to switching systems with uncertainties, 2D switching systems, switching systems with Markovian jumping and switching systems of the Takagi-Sugeno type. The text represents a thoroughly referenced distillation of results obtained in this field during the last decade. The selected tool for analysis and design of stabilizing controllers is based on multiple Lyapunov functions and linear matrix inequalities. All the results are illustrated with numerical examples and figures many of them being modelled using MATLAB®. Saturated Switching Systems will be of interest to academic researchers in con...

  20. Effective switching frequency multiplier inverter

    Science.gov (United States)

    Su, Gui-Jia [Oak Ridge, TN; Peng, Fang Z [Okemos, MI

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  1. FreeSWITCH Cookbook

    CERN Document Server

    Minessale, Anthony

    2012-01-01

    This is a problem-solution approach to take your FreeSWITCH skills to the next level, where everything is explained in a practical way. If you are a system administrator, hobbyist, or someone who uses FreeSWITCH on a regular basis, this book is for you. Whether you are a FreeSWITCH expert or just getting started, this book will take your skills to the next level.

  2. Elements of magnetic switching

    International Nuclear Information System (INIS)

    Aaland, K.

    1983-01-01

    This chapter describes magnetic switching as a method of connecting a capacitor bank (source) to a load; reviews several successful applications of magnetic switching, and discusses switching transformers, limitations and future possibilities. Some of the inflexibility and especially the high cost of magnetic materials may be overcome with the availability of the new splash cooled ribbons (Metglas). Experience has shown that magnetics works despite shock, radiation or noise interferences

  3. Pemodelan Markov Switching Autoregressive

    OpenAIRE

    Ariyani, Fiqria Devi; Warsito, Budi; Yasin, Hasbi

    2014-01-01

    Transition from depreciation to appreciation of exchange rate is one of regime switching that ignored by classic time series model, such as ARIMA, ARCH, or GARCH. Therefore, economic variables are modeled by Markov Switching Autoregressive (MSAR) which consider the regime switching. MLE is not applicable to parameters estimation because regime is an unobservable variable. So that filtering and smoothing process are applied to see the regime probabilities of observation. Using this model, tran...

  4. Transient-Switch-Signal Suppressor

    Science.gov (United States)

    Bozeman, Richard J., Jr.

    1995-01-01

    Circuit delays transmission of switch-opening or switch-closing signal until after preset suppression time. Used to prevent transmission of undesired momentary switch signal. Basic mode of operation simple. Beginning of switch signal initiates timing sequence. If switch signal persists after preset suppression time, circuit transmits switch signal to external circuitry. If switch signal no longer present after suppression time, switch signal deemed transient, and circuit does not pass signal on to external circuitry, as though no transient switch signal. Suppression time preset at value large enough to allow for damping of underlying pressure wave or other mechanical transient.

  5. Computational Investigations of Post-Transcriptional Regulation

    DEFF Research Database (Denmark)

    Rasmussen, Simon Horskjær

    and miRNA regulation was studied by cross-linking immunoprecipitation (CLIP) and RBP double knockdown experiments. A comprehensive analysis of 107 CLIP datasets of 49 RBPs demonstrated that RBPs modulate miRNA regulation. Results suggest it is mediated by RBP-binding hotspots that likely...... investigated using high-throughput data. Analysis of IMP RIP-seq, iCLIP and RNA-seq datasets identified transcripts associated with cytoplasmic IMP ribonucleoproteins. Many of these transcripts were functionally involved in actin cytoskeletal remodeling. Further analyses of this data permitted estimation...... of a bipartite motif, composed of an AU-rich and a CA-rich domain. In addition, a regulatory motif discovery method was developed and applied to identify motifs using differential expression data and CLIP-data in the above investigations. This thesis increased the understanding of the role of RBPs in mi...

  6. Optimal switching using coherent control

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Heuck, Mikkel; Mørk, Jesper

    2013-01-01

    that the switching time, in general, is not limited by the cavity lifetime. Therefore, the total energy required for switching is a more relevant figure of merit than the switching speed, and for a particular two-pulse switching scheme we use calculus of variations to optimize the switching in terms of input energy....

  7. Switched reluctance motor drives

    Indian Academy of Sciences (India)

    Davis RM, Ray WF, Blake RJ 1981 Inverter drive for switched reluctance: circuits and component ratings. Inst. Elec. Eng. Proc. B128: 126-136. Ehsani M. 1991 Position Sensor elimination technique for the switched reluctance motor drive. US Patent No. 5,072,166. Ehsani M, Ramani K R 1993 Direct control strategies based ...

  8. Manually operated coded switch

    International Nuclear Information System (INIS)

    Barnette, J.H.

    1978-01-01

    The disclosure related to a manually operated recodable coded switch in which a code may be inserted, tried and used to actuate a lever controlling an external device. After attempting a code, the switch's code wheels must be returned to their zero positions before another try is made

  9. Switch on, switch off: stiction in nanoelectromechanical switches

    KAUST Repository

    Wagner, Till J W

    2013-06-13

    We present a theoretical investigation of stiction in nanoscale electromechanical contact switches. We develop a mathematical model to describe the deflection of a cantilever beam in response to both electrostatic and van der Waals forces. Particular focus is given to the question of whether adhesive van der Waals forces cause the cantilever to remain in the \\'ON\\' state even when the electrostatic forces are removed. In contrast to previous studies, our theory accounts for deflections with large slopes (i.e. geometrically nonlinear). We solve the resulting equations numerically to study how a cantilever beam adheres to a rigid electrode: transitions between \\'free\\', \\'pinned\\' and \\'clamped\\' states are shown to be discontinuous and to exhibit significant hysteresis. Our findings are compared to previous results from linearized models and the implications for nanoelectromechanical cantilever switch design are discussed. © 2013 IOP Publishing Ltd.

  10. Cell-type-specific genome editing with a microRNA-responsive CRISPR-Cas9 switch.

    Science.gov (United States)

    Hirosawa, Moe; Fujita, Yoshihiko; Parr, Callum J C; Hayashi, Karin; Kashida, Shunnichi; Hotta, Akitsu; Woltjen, Knut; Saito, Hirohide

    2017-07-27

    The CRISPR-Cas9 system is a powerful genome-editing tool useful in a variety of biotechnology and biomedical applications. Here we developed a synthetic RNA-based, microRNA (miRNA)-responsive CRISPR-Cas9 system (miR-Cas9 switch) in which the genome editing activity of Cas9 can be modulated through endogenous miRNA signatures in mammalian cells. We created miR-Cas9 switches by using a miRNA-complementary sequence in the 5΄-UTR of mRNA encoding Streptococcus pyogenes Cas9. The miR-21-Cas9 or miR-302-Cas9 switches selectively and efficiently responded to miR-21-5p in HeLa cells or miR-302a-5p in human induced pluripotent stem cells, and post-transcriptionally attenuated the Cas9 activity only in the target cells. Moreover, the miR-Cas9 switches could differentially control the genome editing by sensing endogenous miRNA activities within a heterogeneous cell population. Our miR-Cas9 switch system provides a promising framework for cell-type selective genome editing and cell engineering based on intracellular miRNA information. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  11. Cell-type-specific genome editing with a microRNA-responsive CRISPR–Cas9 switch

    Science.gov (United States)

    Hirosawa, Moe; Fujita, Yoshihiko; Parr, Callum J. C.; Hayashi, Karin; Kashida, Shunnichi; Hotta, Akitsu; Woltjen, Knut

    2017-01-01

    Abstract The CRISPR–Cas9 system is a powerful genome-editing tool useful in a variety of biotechnology and biomedical applications. Here we developed a synthetic RNA-based, microRNA (miRNA)-responsive CRISPR–Cas9 system (miR-Cas9 switch) in which the genome editing activity of Cas9 can be modulated through endogenous miRNA signatures in mammalian cells. We created miR-Cas9 switches by using a miRNA-complementary sequence in the 5΄-UTR of mRNA encoding Streptococcus pyogenes Cas9. The miR-21-Cas9 or miR-302-Cas9 switches selectively and efficiently responded to miR-21-5p in HeLa cells or miR-302a-5p in human induced pluripotent stem cells, and post-transcriptionally attenuated the Cas9 activity only in the target cells. Moreover, the miR-Cas9 switches could differentially control the genome editing by sensing endogenous miRNA activities within a heterogeneous cell population. Our miR-Cas9 switch system provides a promising framework for cell-type selective genome editing and cell engineering based on intracellular miRNA information. PMID:28525578

  12. Avalanche photoconductive switching

    Science.gov (United States)

    Pocha, M. D.; Druce, R. L.; Wilson, M. J.; Hofer, W. W.

    This paper describes work being done at Lawrence Livermore National Laboratory on the avalanche mode of operation of laser triggered photoconductive switches. We have been able to generate pulses with amplitudes of 2 kV to 35 kV and rise times of 300 to 500 ps, and with a switching gain (energy of output electrical pulse vs energy of trigger optical pulse) of 10(exp 3) to over 10(exp 5). Switches with two very different physical configurations and with two different illumination wavelengths (1.06 micrometer, 890 nm) exhibit very similar behavior. The avalanche switching behavior, therefore, appears to be related to the material parameters rather than the optical wavelength or switch geometry. Considerable further work needs to be done to fully characterize and understand this mode of operation.

  13. Avalanche photoconductive switching

    Energy Technology Data Exchange (ETDEWEB)

    Pocha, M.D.; Druce, R.L.; Wilson, M.J.; Hofer, W.W.

    1989-01-01

    This paper describes work being done at Lawrence Livermore National Laboratory on the avalanche mode of operation of laser triggered photoconductive switches. We have been able to generate pulses with amplitudes of 2 kV--35 kV and rise times of 300--500 ps, and with a switching gain (energy of output electrical pulse vs energy of trigger optical pulse) of 10{sup 3} to over 10{sup 5}. Switches with two very different physical configurations and with two different illumination wavelengths (1.06 {mu}m, 890 nm) exhibit very similar behavior. The avalanche switching behavior, therefore, appears to be related to the material parameters rather than the optical wavelength or switch geometry. Considerable further work needs to be done to fully characterize and understand this mode of operation. 3 refs., 6 figs.

  14. Energy losses in switches

    International Nuclear Information System (INIS)

    Martin, T.H.; Seamen, J.F.; Jobe, D.O.

    1993-01-01

    The authors experiments show energy losses between 2 and 10 times that of the resistive time predictions. The experiments used hydrogen, helium, air, nitrogen, SF 6 polyethylene, and water for the switching dielectric. Previously underestimated switch losses have caused over predicting the accelerator outputs. Accurate estimation of these losses is now necessary for new high-efficiency pulsed power devices where the switching losses constitute the major portion of the total energy loss. They found that the switch energy losses scale as (V peak I peak ) 1.1846 . When using this scaling, the energy losses in any of the tested dielectrics are almost the same. This relationship is valid for several orders of magnitude and suggested a theoretical basis for these results. Currents up to .65 MA, with voltages to 3 MV were applied to various gaps during these experiments. The authors data and the developed theory indicates that the switch power loss continues for a much longer time than the resistive time, with peak power loss generally occurring at peak current in a ranging discharge instead of the early current time. All of the experiments were circuit code modeled after developing a new switch loss version based on the theory. The circuit code predicts switch energy loss and peak currents as a function of time. During analysis of the data they noticed slight constant offsets between the theory and data that depended on the dielectric. They modified the plasma conductivity for each tested dielectric to lessen this offset

  15. Electromechanical magnetization switching

    Energy Technology Data Exchange (ETDEWEB)

    Chudnovsky, Eugene M. [Department of Physics and Astronomy, Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Jaafar, Reem [Department of Mathematics, Engineering and Computer Science, LaGuardia Community College, The City University of New York, 31-10 Thomson Avenue, Long Island City, New York 11101 (United States)

    2015-03-14

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.

  16. Electromechanical magnetization switching

    International Nuclear Information System (INIS)

    Chudnovsky, Eugene M.; Jaafar, Reem

    2015-01-01

    We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained

  17. JUNOS Enterprise Switching

    CERN Document Server

    Reynolds, Harry

    2009-01-01

    JUNOS Enterprise Switching is the only detailed technical book on Juniper Networks' new Ethernet-switching EX product platform. With this book, you'll learn all about the hardware and ASIC design prowess of the EX platform, as well as the JUNOS Software that powers it. Not only is this extremely practical book a useful, hands-on manual to the EX platform, it also makes an excellent study guide for certification exams in the JNTCP enterprise tracks. The authors have based JUNOS Enterprise Switching on their own Juniper training practices and programs, as well as the configuration, maintenanc

  18. Switch mode power supply

    International Nuclear Information System (INIS)

    Kim, Hui Jun

    1993-06-01

    This book concentrates on switch mode power supply. It has four parts, which are introduction of switch mode power supply with DC-DC converter such as Buck converter boost converter, Buck-boost converter and PWM control circuit, explanation for SMPS with DC-DC converter modeling and power mode control, resonance converter like resonance switch, converter, multi resonance converter and series resonance and parallel resonance converters, basic test of SMPS with PWM control circuit, Buck converter, Boost converter, flyback converter, forward converter and IC for control circuit.

  19. Optical switching systems using nanostructures

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2004-01-01

    High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems.......High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems....

  20. IGF-1 deficiency in a critical period early in life influences the vascular aging phenotype in mice by altering miRNA-mediated post-transcriptional gene regulation: implications for the developmental origins of health and disease hypothesis.

    Science.gov (United States)

    Tarantini, Stefano; Giles, Cory B; Wren, Jonathan D; Ashpole, Nicole M; Valcarcel-Ares, M Noa; Wei, Jeanne Y; Sonntag, William E; Ungvari, Zoltan; Csiszar, Anna

    2016-08-01

    Epidemiological findings support the concept of Developmental Origins of Health and Disease, suggesting that early-life hormonal influences during a sensitive period of development have a fundamental impact on vascular health later in life. The endocrine changes that occur during development are highly conserved across mammalian species and include dramatic increases in circulating IGF-1 levels during adolescence. The present study was designed to characterize the effect of developmental IGF-1 deficiency on the vascular aging phenotype. To achieve that goal, early-onset endocrine IGF-1 deficiency was induced in mice by knockdown of IGF-1 in the liver using Cre-lox technology (Igf1 f/f mice crossed with mice expressing albumin-driven Cre recombinase). This model exhibits low-circulating IGF-1 levels during the peripubertal phase of development, which is critical for the biology of aging. Due to the emergence of miRNAs as important regulators of the vascular aging phenotype, the effect of early-life IGF-1 deficiency on miRNA expression profile in the aorta was examined in animals at 27 months of age. We found that developmental IGF-1 deficiency elicits persisting late-life changes in miRNA expression in the vasculature, which significantly differed from those in mice with adult-onset IGF-1 deficiency (TBG-Cre-AAV8-mediated knockdown of IGF-1 at 5 month of age in Igf1 f/f mice). Using a novel computational approach, we identified miRNA target genes that are co-expressed with IGF-1 and associate with aging and vascular pathophysiology. We found that among the predicted targets, the expression of multiple extracellular matrix-related genes, including collagen-encoding genes, were downregulated in mice with developmental IGF-1 deficiency. Collectively, IGF-1 deficiency during a critical period during early in life results in persistent changes in post-transcriptional miRNA-mediated control of genes critical targets for vascular health, which likely contribute to the

  1. Fasting decreases apolipoprotein B mRNA editing and the secretion of small molecular weight apoB by rat hepatocytes: Evidence that the total amount of apoB secreted is regulated post-transcriptionally

    International Nuclear Information System (INIS)

    Leighton, J.K.; Joyner, J.; Zamarripa, J.; Deines, M.; Davis, R.A.

    1990-01-01

    Two different molecular weight forms of apoB are produced from a common initial transcript via editing of a Gln codon (CAA) to a stop codon (UAA), leading to a truncated translation product (apo BS) that consists of the amino terminal half of the larger form (apoBL). Previous studies have shown that fasting coordinately decreases lipogenesis and the secretion of very low density lipoprotein (VLDL) lipids and apoBS. Secretion of the apoBL is unaffected by fasting. We studied whether editing of apoB RNA is repressed by fasting, thus accounting for the selective decreased secretion of apoBS. Column chromatography of [35S]methionine-labeled lipoproteins secreted by hepatocytes from fed rats showed that essentially all of apoBL is secreted in the VLDL fraction, whereas a significant amount (15%) of apoBS is secreted associated as lipoproteins eluting in the HDL fractions. Fasting decreased the relative amount of apoBS that eluted in the VLDL fractions and increased the amount secreted in the HDL fractions. Consistent with previous results, hepatocytes from fasted rats show a selective twofold decrease in apoBS secretion. Fasting did not affect the relative abundance of apoB RNA, determined by slot blot hybridization assays using two different 32P-labeled cDNA probes coding either for both molecular weight forms or for only the large molecular weight form. However, quantitative of the editing of apoB RNA showed that fasting caused a 60% decrease in the amount of apoB RNA possessing the stop codon. These data show that the editing of apoB RNA is sensitive to metabolic state (i.e., fasting) resulting in a selective decrease in the secretion of apoBS. However, since the total secretion of apoB was decreased by fasting, while apoB mRNA levels remained constant, additional (post-transcriptional) mechanisms play a role in regulating apoB secretion

  2. Energy reversible switching from amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.; Smith, Casey; Hussain, Muhammad Mustafa

    2013-01-01

    We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young's modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young's modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

  3. Energy reversible switching from amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-08-01

    We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

  4. Optical computer switching network

    Science.gov (United States)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  5. Stochastic Switching Dynamics

    DEFF Research Database (Denmark)

    Simonsen, Maria

    This thesis treats stochastic systems with switching dynamics. Models with these characteristics are studied from several perspectives. Initially in a simple framework given in the form of stochastic differential equations and, later, in an extended form which fits into the framework of sliding...... mode control. It is investigated how to understand and interpret solutions to models of switched systems, which are exposed to discontinuous dynamics and uncertainties (primarily) in the form of white noise. The goal is to gain knowledge about the performance of the system by interpreting the solution...

  6. Very high plasma switches. Basic plasma physics and switch technology

    International Nuclear Information System (INIS)

    Doucet, H.J.; Roche, M.; Buzzi, J.M.

    1988-01-01

    A review of some high power switches recently developed for very high power technology is made with a special attention to the aspects of plasma physics involved in the mechanisms, which determine the limits of the possible switching parameters

  7. Ultrafast gas switching experiments

    International Nuclear Information System (INIS)

    Frost, C.A.; Martin, T.H.; Patterson, P.E.; Rinehart, L.F.; Rohwein, G.J.; Roose, L.D.; Aurand, J.F.; Buttram, M.T.

    1993-01-01

    We describe recent experiments which studied the physics of ultrafast gas breakdown under the extreme overvoltages which occur when a high pressure gas switch is pulse charged to hundreds of kV in 1 ns or less. The highly overvolted peaking gaps produce powerful electromagnetic pulses with risetimes Khz at > 100 kV/m E field

  8. An integrated circuit switch

    Science.gov (United States)

    Bonin, E. L.

    1969-01-01

    Multi-chip integrated circuit switch consists of a GaAs photon-emitting diode in close proximity with S1 phototransistor. A high current gain is obtained when the transistor has a high forward common-emitter current gain.

  9. The Octopus switch

    NARCIS (Netherlands)

    Havinga, Paul J.M.

    2000-01-01

    This chapter1 discusses the interconnection architecture of the Mobile Digital Companion. The approach to build a low-power handheld multimedia computer presented here is to have autonomous, reconfigurable modules such as network, video and audio devices, interconnected by a switch rather than by a

  10. Untriggered water switching

    International Nuclear Information System (INIS)

    Van Devender, J.P.; Martin, T.H.

    Recent experiments indicate that synchronous untriggered multichannel switching in water will permit the development of relatively simple, ultra-low impedance, short pulse, relativistic electron beam (REB) accelerators. These experiments resulted in the delivery of a 1.5 MV, 0.75 MA, 15 ns pulse into a two-ohm line with a current risetime of 2 x 10 14 A/sec. The apparatus consisted of a 3 MV Marx generator and a series of three 112 cm wide strip water lines separated by two edge-plane water-gap switches. The Marx generator charged the first line in less than 400 ns. The first switch then formed five or more channels. The second line was charged in 60 ns and broke down with 10 to 25 channels at a mean field of 1.6 MV/cm. The closure time of each spark channel along both switches was measured with a streak camera and showed low jitter. The resulting fast pulse line construction is simpler and should provide considerable costs savings from previous designs. Multiples of these low impedance lines in parallel can be employed to obtain power levels in the 10 14 W range for REB fusion studies. (U.S.)

  11. Evolution of RLSB, a nuclear-encoded S1 domain RNA binding protein associated with post-transcriptional regulation of plastid-encoded rbcL mRNA in vascular plants.

    Science.gov (United States)

    Yerramsetty, Pradeep; Stata, Matt; Siford, Rebecca; Sage, Tammy L; Sage, Rowan F; Wong, Gane Ka-Shu; Albert, Victor A; Berry, James O

    2016-06-29

    RLSB, an S-1 domain RNA binding protein of Arabidopsis, selectively binds rbcL mRNA and co-localizes with Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) within chloroplasts of C3 and C4 plants. Previous studies using both Arabidopsis (C3) and maize (C4) suggest RLSB homologs are post-transcriptional regulators of plastid-encoded rbcL mRNA. While RLSB accumulates in all Arabidopsis leaf chlorenchyma cells, in C4 leaves RLSB-like proteins accumulate only within Rubisco-containing bundle sheath chloroplasts of Kranz-type species, and only within central compartment chloroplasts in the single cell C4 plant Bienertia. Our recent evidence implicates this mRNA binding protein as a primary determinant of rbcL expression, cellular localization/compartmentalization, and photosynthetic function in all multicellular green plants. This study addresses the hypothesis that RLSB is a highly conserved Rubisco regulatory factor that occurs in the chloroplasts all higher plants. Phylogenetic analysis has identified RLSB orthologs and paralogs in all major plant groups, from ancient liverworts to recent angiosperms. RLSB homologs were also identified in algae of the division Charophyta, a lineage closely related to land plants. RLSB-like sequences were not identified in any other algae, suggesting that it may be specific to the evolutionary line leading to land plants. The RLSB family occurs in single copy across most angiosperms, although a few species with two copies were identified, seemingly randomly distributed throughout the various taxa, although perhaps correlating in some cases with known ancient whole genome duplications. Monocots of the order Poales (Poaceae and Cyperaceae) were found to contain two copies, designated here as RLSB-a and RLSB-b, with only RLSB-a implicated in the regulation of rbcL across the maize developmental gradient. Analysis of microsynteny in angiosperms revealed high levels of conservation across eudicot species and for both paralogs in

  12. AIDing Chromatin and Transcription-Coupled Orchestration of Immunoglobulin Class-Switch Recombination

    Science.gov (United States)

    Vaidyanathan, Bharat; Yen, Wei-Feng; Pucella, Joseph N.; Chaudhuri, Jayanta

    2014-01-01

    Secondary diversification of the antibody repertoire upon antigenic challenge, in the form of immunoglobulin heavy chain (IgH) class-switch recombination (CSR) endows mature, naïve B cells in peripheral lymphoid organs with a limitless ability to mount an optimal humoral immune response, thus expediting pathogen elimination. CSR replaces the default constant (CH) region exons (Cμ) of IgH with any of the downstream CH exons (Cγ, Cε, or Cα), thereby altering effector functions of the antibody molecule. This process depends on, and is orchestrated by, activation-induced deaminase (AID), a DNA cytidine deaminase that acts on single-stranded DNA exposed during transcription of switch (S) region sequences at the IgH locus. DNA lesions thus generated are processed by components of several general DNA repair pathways to drive CSR. Given that AID can instigate DNA lesions and genomic instability, stringent checks are imposed that constrain and restrict its mutagenic potential. In this review, we will discuss how AID expression and substrate specificity and activity is rigorously enforced at the transcriptional, post-transcriptional, post-translational, and epigenetic levels, and how the DNA-damage response is choreographed with precision to permit targeted activity while limiting bystander catastrophe. PMID:24734031

  13. Control synthesis of switched systems

    CERN Document Server

    Zhao, Xudong; Niu, Ben; Wu, Tingting

    2017-01-01

    This book offers its readers a detailed overview of the synthesis of switched systems, with a focus on switching stabilization and intelligent control. The problems investigated are not only previously unsolved theoretically but also of practical importance in many applications: voltage conversion, naval piloting and navigation and robotics, for example. The book considers general switched-system models and provides more efficient design methods to bring together theory and application more closely than was possible using classical methods. It also discusses several different classes of switched systems. For general switched linear systems and switched nonlinear systems comprising unstable subsystems, it introduces novel ideas such as invariant subspace theory and the time-scheduled Lyapunov function method of designing switching signals to stabilize the underlying systems. For some typical switched nonlinear systems affected by various complex dynamics, the book proposes novel design approaches based on inte...

  14. Synchronization Between Two Different Switched Chaotic Systems By Switching Control

    Directory of Open Access Journals (Sweden)

    Du Li Ming

    2016-01-01

    Full Text Available This paper is concerned with the synchronization problem of two different switched chaotic systems, considering the general case that the master-slave switched chaotic systems have uncertainties. Two basic problems are considered: one is projective synchronization of switched chaotic systems under arbitrary switching; the other is projective synchronization of switched chaotic systems by design of switching when synchronization cannot achieved by using any subsystems alone. For the two problems, common Lyapunov function method and multiple Lyapunov function method are used respectively, an adaptive control scheme has been presented, some sufficient synchronization conditions are attainted, and the switching signal is designed. Finally, the numerical simulation is provide to show the effectiveness of our method.

  15. Emerging roles of microRNAs as molecular switches in the integrated circuit of the cancer cell

    Science.gov (United States)

    Sotiropoulou, Georgia; Pampalakis, Georgios; Lianidou, Evi; Mourelatos, Zissimos

    2009-01-01

    Transformation of normal cells into malignant tumors requires the acquisition of six hallmark traits, e.g., self-sufficiency in growth signals, insensitivity to antigrowth signals and self-renewal, evasion of apoptosis, limitless replication potential, angiogenesis, invasion, and metastasis, which are common to all cancers (Hanahan and Weinberg 2000). These new cellular traits evolve from defects in major regulatory microcircuits that are fundamental for normal homeostasis. The discovery of microRNAs (miRNAs) as a new class of small non-protein-coding RNAs that control gene expression post-transcriptionally by binding to various mRNA targets suggests that these tiny RNA molecules likely act as molecular switches in the extensive regulatory web that involves thousands of transcripts. Most importantly, accumulating evidence suggests that numerous microRNAs are aberrantly expressed in human cancers. In this review, we discuss the emergent roles of microRNAs as switches that function to turn on/off known cellular microcircuits. We outline recent compelling evidence that deregulated microRNA-mediated control of cellular microcircuits cooperates with other well-established regulatory mechanisms to confer the hallmark traits of the cancer cell. Furthermore, these exciting insights into aberrant microRNA control in cancer-associated circuits may be exploited for cancer therapies that will target deregulated miRNA switches. PMID:19561119

  16. Laser activated superconducting switch

    International Nuclear Information System (INIS)

    Wolf, A.A.

    1976-01-01

    A superconducting switch or bistable device is described consisting of a superconductor in a cryogen maintaining a temperature just below the transition temperature, having a window of the proper optical frequency band for passing a laser beam which may impinge on the superconductor when desired. The frequency of the laser is equal to or greater than the optical absorption frequency of the superconducting material and is consistent with the ratio of the gap energy of the switch material to Planck's constant, to cause depairing of electrons, and thereby normalize the superconductor. Some embodiments comprise first and second superconducting metals. Other embodiments feature the two superconducting metals separated by a thin film insulator through which the superconducting electrons tunnel during superconductivity

  17. Optical fiber switch

    Science.gov (United States)

    Early, James W.; Lester, Charles S.

    2002-01-01

    Optical fiber switches operated by electrical activation of at least one laser light modulator through which laser light is directed into at least one polarizer are used for the sequential transport of laser light from a single laser into a plurality of optical fibers. In one embodiment of the invention, laser light from a single excitation laser is sequentially transported to a plurality of optical fibers which in turn transport the laser light to separate individual remotely located laser fuel ignitors. The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.

  18. Coulomb Blockade Plasmonic Switch.

    Science.gov (United States)

    Xiang, Dao; Wu, Jian; Gordon, Reuven

    2017-04-12

    Tunnel resistance can be modulated with bias via the Coulomb blockade effect, which gives a highly nonlinear response current. Here we investigate the optical response of a metal-insulator-nanoparticle-insulator-metal structure and show switching of a plasmonic gap from insulator to conductor via Coulomb blockade. By introducing a sufficiently large charging energy in the tunnelling gap, the Coulomb blockade allows for a conductor (tunneling) to insulator (capacitor) transition. The tunnelling electrons can be delocalized over the nanocapacitor again when a high energy penalty is added with bias. We demonstrate that this has a huge impact on the plasmonic resonance of a 0.51 nm tunneling gap with ∼70% change in normalized optical loss. Because this structure has a tiny capacitance, there is potential to harness the effect for high-speed switching.

  19. Cryogenic switched MOSFET characterization

    Science.gov (United States)

    1981-01-01

    Both p channel and n channel enhancement mode MOSFETs can be readily switched on and off at temperatures as low as 2.8 K so that switch sampled readout of a VLWIR Ge:Ga focal plane is electronically possible. Noise levels as low as 100 rms electrons per sample (independent of sample rate) can be achieved using existing p channel MOSFETs, at overall rates up to 30,000 samples/second per multiplexed channel (e.g., 32 detectors at a rate of almost 1,000 frames/second). Run of the mill devices, including very low power dissipation n channel FETs would still permit noise levels of the order of 500 electrons/sample.

  20. Practical switching power supply design

    CERN Document Server

    Brown, Martin C

    1990-01-01

    Take the ""black magic"" out of switching power supplies with Practical Switching Power Supply Design! This is a comprehensive ""hands-on"" guide to the theory behind, and design of, PWM and resonant switching supplies. You'll find information on switching supply operation and selecting an appropriate topology for your application. There's extensive coverage of buck, boost, flyback, push-pull, half bridge, and full bridge regulator circuits. Special attention is given to semiconductors used in switching supplies. RFI/EMI reduction, grounding, testing, and safety standards are also deta

  1. Composite Material Switches

    Science.gov (United States)

    Javadi, Hamid (Inventor)

    2002-01-01

    A device to protect electronic circuitry from high voltage transients is constructed from a relatively thin piece of conductive composite sandwiched between two conductors so that conduction is through the thickness of the composite piece. The device is based on the discovery that conduction through conductive composite materials in this configuration switches to a high resistance mode when exposed to voltages above a threshold voltage.

  2. MCT/MOSFET Switch

    Science.gov (United States)

    Rippel, Wally E.

    1990-01-01

    Metal-oxide/semiconductor-controlled thyristor (MCT) and metal-oxide/semiconductor field-effect transistor (MOSFET) connected in switching circuit to obtain better performance. Offers high utilization of silicon, low forward voltage drop during "on" period of operating cycle, fast turnon and turnoff, and large turnoff safe operating area. Includes ability to operate at high temperatures, high static blocking voltage, and ease of drive.

  3. Python Switch Statement

    Directory of Open Access Journals (Sweden)

    2008-06-01

    Full Text Available The Python programming language does not have a built in switch/case control structure as found in many other high level programming languages. It is thought by some that this is a deficiency in the language, and the control structure should be added. This paper demonstrates that not only is the control structure not needed, but that the methods available in Python are more expressive than built in case statements in other high level languages.

  4. Ferroelectric switching of elastin

    Science.gov (United States)

    Liu, Yuanming; Cai, Hong-Ling; Zelisko, Matthew; Wang, Yunjie; Sun, Jinglan; Yan, Fei; Ma, Feiyue; Wang, Peiqi; Chen, Qian Nataly; Zheng, Hairong; Meng, Xiangjian; Sharma, Pradeep; Zhang, Yanhang; Li, Jiangyu

    2014-01-01

    Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present compelling evidence that elastin, the key ECM protein found in connective tissues, is ferroelectric, and we elucidate the molecular mechanism of its switching. Nanoscale piezoresponse force microscopy and macroscopic pyroelectric measurements both show that elastin retains ferroelectricity at 473 K, with polarization on the order of 1 μC/cm2, whereas coarse-grained molecular dynamics simulations predict similar polarization with a Curie temperature of 580 K, which is higher than most synthetic molecular ferroelectrics. The polarization of elastin is found to be intrinsic in tropoelastin at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics, and it switches via thermally activated cooperative rotation of dipoles. Our study sheds light onto a long-standing question on ferroelectric switching in biology and establishes ferroelectricity as an important biophysical property of proteins. This is a critical first step toward resolving its physiological significance and pathological implications. PMID:24958890

  5. MENGAPA PERUSAHAAN MELAKUKAN AUDITOR SWITCH?

    Directory of Open Access Journals (Sweden)

    Kadek Sumadi

    2011-01-01

    Full Text Available The existence of a large number of accounting firms allowsprovides companies choices whether to stay with current firm or switchto another accounting firm. Decision of Minister of FinanceNo.423/KMK.06/2002 states that a company must switch auditor afterfive years of consecutive assignment. This is mandatory. The questionrises when a company voluntarily switches its auditor. Why does thishappen?One of the reasons is that management does not satisfy withauditor opinion, except for unqualified opinion. New management teamwould directly or indirectly encourage auditor switch to align accountingand reporting policies. Moreover an expanding company expects positivereaction when it does auditor switch. Profitability is also one reason fora company to switch auditor, for example, when a company earns moreprofit it tends to hire more credible auditor. On the other hand, when thecompany faces a financial distress, it probably would switch auditor aswell.

  6. Low-Crosstalk Composite Optical Crosspoint Switches

    Science.gov (United States)

    Pan, Jing-Jong; Liang, Frank

    1993-01-01

    Composite optical switch includes two elementary optical switches in tandem, plus optical absorbers. Like elementary optical switches, composite optical switches assembled into switch matrix. Performance enhanced by increasing number of elementary switches. Advantage of concept: crosstalk reduced to acceptably low level at moderate cost of doubling number of elementary switches rather than at greater cost of tightening manufacturing tolerances and exerting more-precise control over operating conditions.

  7. Compound semiconductor optical waveguide switch

    Science.gov (United States)

    Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

    2003-06-10

    An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

  8. Neuromorphic atomic switch networks.

    Directory of Open Access Journals (Sweden)

    Audrius V Avizienis

    Full Text Available Efforts to emulate the formidable information processing capabilities of the brain through neuromorphic engineering have been bolstered by recent progress in the fabrication of nonlinear, nanoscale circuit elements that exhibit synapse-like operational characteristics. However, conventional fabrication techniques are unable to efficiently generate structures with the highly complex interconnectivity found in biological neuronal networks. Here we demonstrate the physical realization of a self-assembled neuromorphic device which implements basic concepts of systems neuroscience through a hardware-based platform comprised of over a billion interconnected atomic-switch inorganic synapses embedded in a complex network of silver nanowires. Observations of network activation and passive harmonic generation demonstrate a collective response to input stimulus in agreement with recent theoretical predictions. Further, emergent behaviors unique to the complex network of atomic switches and akin to brain function are observed, namely spatially distributed memory, recurrent dynamics and the activation of feedforward subnetworks. These devices display the functional characteristics required for implementing unconventional, biologically and neurally inspired computational methodologies in a synthetic experimental system.

  9. Recent developments in switching theory

    CERN Document Server

    Mukhopadhyay, Amar

    2013-01-01

    Electrical Science Series: Recent Developments in Switching Theory covers the progress in the study of the switching theory. The book discusses the simplified proof of Post's theorem on completeness of logic primitives; the role of feedback in combinational switching circuits; and the systematic procedure for the design of Lupanov decoding networks. The text also describes the classical results on counting theorems and their application to the classification of switching functions under different notions of equivalence, including linear and affine equivalences. The development of abstract har

  10. Software Switching for Data Acquisition

    CERN Multimedia

    CERN. Geneva; Malone, David

    2016-01-01

    In this talk we discuss the feasibility of replacing telecom-class routers with a topology of commodity servers acting as software switches in data acquisition. We extend the popular software switch, Open vSwitch, with a dedicated, throughput-oriented buffering mechanism. We compare the performance under heavy many-to-one congestion to typical Ethernet switches and evaluate the scalability when building larger topologies, exploiting the integration with software-defined networking technologies. Please note that David Malone will speak on behalf of Grzegorz Jereczek.

  11. Hybrid switch for resonant power converters

    Science.gov (United States)

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  12. LCT protective dump-switch tests

    International Nuclear Information System (INIS)

    Parsons, W.M.

    1981-01-01

    Each of the six coils in the Large Coil Task (LCT) has a separate power supply, dump resistor, and switching circuit. Each switching circuit contains five switches, two of which are redundant. The three remaining switches perform separate duties in an emergency dump situation. These three switches were tested to determine their ability to meet the LCT conditions

  13. EDITORIAL: Molecular switches at surfaces Molecular switches at surfaces

    Science.gov (United States)

    Weinelt, Martin; von Oppen, Felix

    2012-10-01

    In nature, molecules exploit interaction with their environment to realize complex functionalities on the nanometer length scale. Physical, chemical and/or biological specificity is frequently achieved by the switching of molecules between microscopically different states. Paradigmatic examples are the energy production in proton pumps of bacteria or the signal conversion in human vision, which rely on switching molecules between different configurations or conformations by external stimuli. The remarkable reproducibility and unparalleled fatigue resistance of these natural processes makes it highly desirable to emulate nature and develop artificial systems with molecular functionalities. A promising avenue towards this goal is to anchor the molecular switches at surfaces, offering new pathways to control their functional properties, to apply electrical contacts, or to integrate switches into larger systems. Anchoring at surfaces allows one to access the full range from individual molecular switches to self-assembled monolayers of well-defined geometry and to customize the coupling between molecules and substrate or between adsorbed molecules. Progress in this field requires both synthesis and preparation of appropriate molecular systems and control over suitable external stimuli, such as light, heat, or electrical currents. To optimize switching and generate function, it is essential to unravel the geometric structure, the electronic properties and the dynamic interactions of the molecular switches on surfaces. This special section, Molecular Switches at Surfaces, collects 17 contributions describing different aspects of this research field. They analyze elementary processes, both in single molecules and in ensembles of molecules, which involve molecular switching and concomitant changes of optical, electronic, or magnetic properties. Two topical reviews summarize the current status, including both challenges and achievements in the field of molecular switches on

  14. Circuit switched optical networks

    DEFF Research Database (Denmark)

    Kloch, Allan

    2003-01-01

    Some of the most important components required for enabling optical networking are investigated through both experiments and modelling. These all-optical components are the wavelength converter, the regenerator and the space switch. When these devices become "off-the-shelf" products, optical cross......, it is expected that the optical solution will offer an economical benefit for hight bit rate networks. This thesis begins with a discussion of the expected impact on communications systems from the rapidly growing IP traffic, which is expected to become the dominant source for traffic. IP traffic has some...... characteristics, which are best supported by an optical network. The interest for such an optical network is exemplified by the formation of the ACTS OPEN project which aim was to investigate the feasibility of an optical network covering Europe. Part of the work presented in this thesis is carried out within...

  15. Photo-switching element

    Energy Technology Data Exchange (ETDEWEB)

    Masaki, Yuichi

    1987-10-31

    Photo-input MOS transistor (Photo-switching element) cannot give enough ON/OFF ratio but requires an auxiliary condenser for a certain type of application. In addition, PN junction of amorphous silicon is not practical because it gives high leak current resulting in low electromotive force. In this invention, a solar cell was constructed with a lower electrode consisting of a transparent electro-conducting film, a photosensitive part consisting of an amorphous Si layer of p-i-n layer construction, and an upper metal electrode consisting of Cr or Nichrome, and a thin film transistor was placed on the solar cell, and further the upper metal electrode was co-used as a gate electrode of the thin film transistor; this set-up of this invention enabled to attain an efficient photo-electric conversion of the incident light, high electromotive force of the solar cell, and the transistor with high ON/OFF ratio. (3 figs)

  16. Battery switch for downhole tools

    Science.gov (United States)

    Boling, Brian E.

    2010-02-23

    An electrical circuit for a downhole tool may include a battery, a load electrically connected to the battery, and at least one switch electrically connected in series with the battery and to the load. The at least one switch may be configured to close when a tool temperature exceeds a selected temperature.

  17. Improved switch-resistor packaging

    Science.gov (United States)

    Redmerski, R. E.

    1980-01-01

    Packaging approach makes resistors more accessible and easily identified with specific switches. Failures are repaired more quickly because of improved accessibility. Typical board includes one resistor that acts as circuit breaker, and others are positioned so that their values can be easily measured when switch is operated. Approach saves weight by using less wire and saves valuable panel space.

  18. Superconductivity, energy storage and switching

    International Nuclear Information System (INIS)

    Laquer, H.L.

    1974-01-01

    The phenomenon of superconductivity can contribute to the technology of energy storage and switching in two distinct ways. On one hand the zero resistivity of the superconductor can produce essentially infinite time constants so that an inductive storage system can be charged from very low power sources. On the other hand, the recovery of finite resistivity in a normal-going superconducting switch can take place in extremely short times, so that a system can be made to deliver energy at a very high power level. Topics reviewed include: physics of superconductivity, limits to switching speed of superconductors, physical and engineering properties of superconducting materials and assemblies, switching methods, load impedance considerations, refrigeration economics, limitations imposed by present day and near term technology, performance of existing and planned energy storage systems, and a comparison with some alternative methods of storing and switching energy. (U.S.)

  19. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.; Smith, Casey; Hussain, Muhammad Mustafa

    2013-01-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  20. Amorphous metal based nanoelectromechanical switch

    KAUST Repository

    Mayet, Abdulilah M.

    2013-04-01

    Nanoelectromechanical (NEM) switch is an interesting ultra-low power option which can operate in the harsh environment and can be a complementary element in complex digital circuitry. Although significant advancement is happening in this field, report on ultra-low voltage (pull-in) switch which offers high switching speed and area efficiency is yet to be made. One key challenge to achieve such characteristics is to fabricate nano-scale switches with amorphous metal so the shape and dimensional integrity are maintained to achieve the desired performance. Therefore, we report a tungsten alloy based amorphous metal with fabrication process development of laterally actuated dual gated NEM switches with 100 nm width and 200 nm air-gap to result in <5 volts of actuation voltage (Vpull-in). © 2013 IEEE.

  1. Switching Phenomena in a System with No Switches

    Science.gov (United States)

    Preis, Tobias; Stanley, H. Eugene

    2010-02-01

    It is widely believed that switching phenomena require switches, but this is actually not true. For an intriguing variety of switching phenomena in nature, the underlying complex system abruptly changes from one state to another in a highly discontinuous fashion. For example, financial market fluctuations are characterized by many abrupt switchings creating increasing trends ("bubble formation") and decreasing trends ("financial collapse"). Such switching occurs on time scales ranging from macroscopic bubbles persisting for hundreds of days to microscopic bubbles persisting only for a few seconds. We analyze a database containing 13,991,275 German DAX Future transactions recorded with a time resolution of 10 msec. For comparison, a database providing 2,592,531 of all S&P500 daily closing prices is used. We ask whether these ubiquitous switching phenomena have quantifiable features independent of the time horizon studied. We find striking scale-free behavior of the volatility after each switching occurs. We interpret our findings as being consistent with time-dependent collective behavior of financial market participants. We test the possible universality of our result by performing a parallel analysis of fluctuations in transaction volume and time intervals between trades. We show that these financial market switching processes have properties similar to those of phase transitions. We suggest that the well-known catastrophic bubbles that occur on large time scales—such as the most recent financial crisis—are no outliers but single dramatic representatives caused by the switching between upward and downward trends on time scales varying over nine orders of magnitude from very large (≈102 days) down to very small (≈10 ms).

  2. Complex relationship between mismatch repair proteins and MBD4 during immunoglobulin class switch recombination.

    Science.gov (United States)

    Grigera, Fernando; Bellacosa, Alfonso; Kenter, Amy L

    2013-01-01

    Mismatch repair (MMR) safeguards against genomic instability and is required for efficient Ig class switch recombination (CSR). Methyl CpG binding domain protein 4 (MBD4) binds to MutL homologue 1 (MLH1) and controls the post-transcriptional level of several MMR proteins, including MutS homologue 2 (MSH2). We show that in WT B cells activated for CSR, MBD4 is induced and interacts with MMR proteins, thereby implying a role for MBD4 in CSR. However, CSR is in the normal range in Mbd4 deficient mice deleted for exons 2-5 despite concomitant reduction of MSH2. We show by comparison in Msh2(+/-) B cells that a two-fold reduction of MSH2 and MBD4 proteins is correlated with impaired CSR. It is therefore surprising that CSR occurs at normal frequencies in the Mbd4 deficient B cells where MSH2 is reduced. We find that a variant Mbd4 transcript spanning exons 1,6-8 is expressed in Mbd4 deficient B cells. This transcript can be ectopically expressed and produces a truncated MBD4 peptide. Thus, the 3' end of the Mbd4 locus is not silent in Mbd4 deficient B cells and may contribute to CSR. Our findings highlight a complex relationship between MBD4 and MMR proteins in B cells and a potential reconsideration of their role in CSR.

  3. DETERMINANT OF DOWNWARD AUDITOR SWITCHING

    Directory of Open Access Journals (Sweden)

    Totok Budisantoso

    2017-12-01

    Full Text Available Abstract: Determinant of Downward Auditor Switching. This study examines the factors that influence downward auditor switching in five ASEAN countries. Fixed effect logistic regression was used as analytical method. This study found that opinion shopping occurred in ASEAN, especially in distress companies. Companies with complex businesses will retain the Big Four auditors to reduce complexity and audit costs. Audit and public committees serve as guardians of auditor quality. On the other hand, shareholders failed to maintain audit quality. It indicates that there is entrenchment effect in auditor switching.

  4. Electrically switched ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lilga, M.A. [Pacific Northwest National Lab., Richland, WA (United States); Schwartz, D.T.; Genders, D.

    1997-10-01

    A variety of waste types containing radioactive {sup 137}Cs are found throughout the DOE complex. These waste types include water in reactor cooling basins, radioactive high-level waste (HLW) in underground storage tanks, and groundwater. Safety and regulatory requirements and economics require the removal of radiocesium before these wastes can be permanently disposed of. Electrically Switched Ion Exchange (ESIX) is an approach for radioactive cesium separation that combines IX and electrochemistry to provide a selective, reversible, and economic separation method that also produces little or no secondary waste. In the ESIX process, an electroactive IX film is deposited electrochemically onto a high-surface area electrode, and ion uptake and elution are controlled directly by modulating the potential of the film. For cesium, the electroactive films under investigation are ferrocyanides, which are well known to have high selectivities for cesium in concentrated sodium solutions. When a cathode potential is applied to the film, Fe{sup +3} is reduced to the Fe{sup +2} state, and a cation must be intercalated into the film to maintain charge neutrality (i.e., Cs{sup +} is loaded). Conversely, if an anodic potential is applied, a cation must be released from the film (i.e., Cs{sup +} is unloaded). Therefore, to load the film with cesium, the film is simply reduced; to unload cesium, the film is oxidized.

  5. High current vacuum closing switch

    International Nuclear Information System (INIS)

    Dolgachev, G.I.; Maslennikov, D.D.; Romanov, A.S.; Ushakov, A.G.

    2005-01-01

    The paper proposes a powerful pulsed closing vacuum switch for high current commutation consisting of series of the vacuum diodes with near 1 mm gaps having closing time determined by the gaps shortening with the near-electrode plasmas [ru

  6. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [State Univ. of New York (SUNY), Plattsburgh, NY (United States); Univ. of California, Davis, CA (United States)

    2012-01-20

    Photoconductive semiconductor switches (PCSS) have been investigated since the late 1970s. Some devices have been developed that withstand tens of kilovolts and others that switch hundreds of amperes. However, no single device has been developed that can reliably withstand both high voltage and switch high current. Yet, photoconductive switches still hold the promise of reliable high voltage and high current operation with subnanosecond risetimes. Particularly since good quality, bulk, single crystal, wide bandgap semiconductor materials have recently become available. In this chapter we will review the basic operation of PCSS devices, status of PCSS devices and properties of the wide bandgap semiconductors 4H-SiC, 6H-SiC and 2H-GaN.

  7. Switching of chirality by light

    NARCIS (Netherlands)

    Feringa, B.L.; Schoevaars, A.M; Jager, W.F.; de Lange, B.; Huck, N.P.M.

    1996-01-01

    Optically active photoresponsive molecules are described by which control of chirality is achieved by light. These chiroptical molecular switches are based on inherently dissymmetric overcrowded alkenes and the synthesis, resolution and dynamic stereochemical properties are discussed. Introduction

  8. Aurora oil switch upgrade program

    International Nuclear Information System (INIS)

    Warren, T.

    1989-03-01

    This report describes the short pulse synchronization requirements, the original Aurora trigger scheme, and the PI/SNLA approach to improving the synchronization. It also describes the oil switching design study undertaken as the first phase of the program. A discussion of oil-switch closure analysis and the conceptual design motivated by this analysis are presented. This paper also describes the oil-switch trigger pulser tests required to validate the concept. This includes the design of the testing facility, a description of the test goals, and a discussion of the results. This paper finally describes oil-switch trigger pulser testing on one of the four Aurora Blumlein modules, which includes the hardware design and operation, the testing goals, hardware installation, and test results. 9 refs., 26 figs

  9. Solid state bistable power switch

    Science.gov (United States)

    Bartko, J.; Shulman, H.

    1970-01-01

    Tin and copper provide high current and switching time capabilities for high-current resettable fuses. They show the best performance for trip current and degree of reliability, and have low coefficients of thermal expansion.

  10. Intrinsic nanofilamentation in resistive switching

    KAUST Repository

    Wu, Xing; Cha, Dong Kyu; Bosman, Michel; Raghavan, Nagarajan; Migas, Dmitri B.; Borisenko, Victor E.; Zhang, Xixiang; Li, Kun; Pey, Kin-Leong

    2013-01-01

    -chip circuitry and non-volatile memory storage. Here, we provide insight into the mechanisms that govern highly reproducible controlled resistive switching via a nanofilament by using an asymmetric metal-insulator-semiconductor structure. In-situ transmission

  11. Electron collisions in gas switches

    International Nuclear Information System (INIS)

    Christophorou, L.G.

    1989-01-01

    Many technologies rely on the conduction/insulation properties of gaseous matter for their successful operation. Many others (e.g., pulsed power technologies) rely on the rapid change (switching or modulation) of the properties of gaseous matter from an insulator to a conductor and vice versa. Studies of electron collision processes in gases aided the development of pulsed power gas switches, and in this paper we shall briefly illustrate the kind of knowledge on electron collision processes which is needed to optimize the performance of such switching devices. To this end, we shall refer to three types of gas switches: spark gap closing, self-sustained diffuse discharge closing, and externally-sustained diffuse discharge opening. 24 refs., 15 figs., 2 tabs

  12. A Piezoelectric Cryogenic Heat Switch

    Science.gov (United States)

    Jahromi, Amir E.; Sullivan, Dan F.

    2014-01-01

    We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios greater than 100 were achieved when the positioner applied its maximum force of 8 N. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an optimized PZHS.

  13. High PRF high current switch

    Science.gov (United States)

    Moran, Stuart L.; Hutcherson, R. Kenneth

    1990-03-27

    A triggerable, high voltage, high current, spark gap switch for use in pu power systems. The device comprises a pair of electrodes in a high pressure hydrogen environment that is triggered by introducing an arc between one electrode and a trigger pin. Unusually high repetition rates may be obtained by undervolting the switch, i.e., operating the trigger at voltages much below the self-breakdown voltage of the device.

  14. Chromatic interocular-switch rivalry.

    Science.gov (United States)

    Christiansen, Jens H; D'Antona, Anthony D; Shevell, Steven K

    2017-05-01

    Interocular-switch rivalry (also known as stimulus rivalry) is a kind of binocular rivalry in which two rivalrous images are swapped between the eyes several times a second. The result is stable periods of one image and then the other, with stable intervals that span many eye swaps (Logothetis, Leopold, & Sheinberg, 1996). Previous work used this close kin of binocular rivalry with rivalrous forms. Experiments here test whether chromatic interocular-switch rivalry, in which the swapped stimuli differ in only chromaticity, results in slow alternation between two colors. Swapping equiluminant rivalrous chromaticities at 3.75 Hz resulted in slow perceptual color alternation, with one or the other color often continuously visible for two seconds or longer (during which there were 15+ eye swaps). A well-known theory for sustained percepts from interocular-switch rivalry with form is inhibitory competition between binocular neurons driven by monocular neurons with matched orientation tuning in each eye; such binocular neurons would produce a stable response when a given orientation is swapped between the eyes. A similar model can account for the percepts here from chromatic interocular-switch rivalry and is underpinned by the neurophysiological finding that color-preferring binocular neurons are driven by monocular neurons from each eye with well-matched chromatic selectivity (Peirce, Solomon, Forte, & Lennie, 2008). In contrast to chromatic interocular-switch rivalry, luminance interocular-switch rivalry with swapped stimuli that differ in only luminance did not result in slowly alternating percepts of different brightnesses.

  15. CONTROL OF BOUNCING IN RF MEMS SWITCHES USING DOUBLE ELECTRODE

    KAUST Repository

    Abdul Rahim, Farhan

    2014-01-01

    MEMS based mechanical switches are seen to be the likely replacements for CMOS based switches due to the several advantages that these mechanical switches have over CMOS switches. Mechanical switches can be used in systems under extreme conditions

  16. MicroRNA-Mediated Positive Feedback Loop and Optimized Bistable Switch in a Cancer Network Involving miR-17-92

    Science.gov (United States)

    Li, Yichen; Li, Yumin; Zhang, Hui; Chen, Yong

    2011-01-01

    MicroRNAs (miRNAs) are small, noncoding RNAs that play an important role in many key biological processes, including development, cell differentiation, the cell cycle and apoptosis, as central post-transcriptional regulators of gene expression. Recent studies have shown that miRNAs can act as oncogenes and tumor suppressors depending on the context. The present work focuses on the physiological significance of miRNAs and their role in regulating the switching behavior. We illustrate an abstract model of the Myc/E2F/miR-17-92 network presented by Aguda et al. (2008), which is composed of coupling between the E2F/Myc positive feedback loops and the E2F/Myc/miR-17-92 negative feedback loop. By systematically analyzing the network in close association with plausible experimental parameters, we show that, in the presence of miRNAs, the system bistability emerges from the system, with a bistable switch and a one-way switch presented by Aguda et al. instead of a single one-way switch. Moreover, the miRNAs can optimize the switching process. The model produces a diverse array of response-signal behaviors in response to various potential regulating scenarios. The model predicts that this transition exists, one from cell death or the cancerous phenotype directly to cell quiescence, due to the existence of miRNAs. It was also found that the network involving miR-17-92 exhibits high noise sensitivity due to a positive feedback loop and also maintains resistance to noise from a negative feedback loop. PMID:22022595

  17. Switched capacitor DC-DC converter with switch conductance modulation and Pesudo-fixed frequency control

    DEFF Research Database (Denmark)

    Larsen, Dennis Øland; Vinter, Martin; Jørgensen, Ivan Harald Holger

    A switched capacitor dc-dc converter with frequency-planned control is presented. By splitting the output stage switches in eight segments the output voltage can be regulated with a combination of switching frequency and switch conductance. This allows for switching at predetermined frequencies, 31...

  18. A Switch Is Not a Switch: Syntactically-Driven Bilingual Language Control

    Science.gov (United States)

    Gollan, Tamar H.; Goldrick, Matthew

    2018-01-01

    The current study investigated the possibility that language switches could be relatively automatically triggered by context. "Single-word switches," in which bilinguals switched languages on a single word in midsentence and then immediately switched back, were contrasted with more complete "whole-language switches," in which…

  19. Principles of broadband switching and networking

    CERN Document Server

    Liew, Soung C

    2010-01-01

    An authoritative introduction to the roles of switching and transmission in broadband integrated services networks Principles of Broadband Switching and Networking explains the design and analysis of switch architectures suitable for broadband integrated services networks, emphasizing packet-switched interconnection networks with distributed routing algorithms. The text examines the mathematical properties of these networks, rather than specific implementation technologies. Although the pedagogical explanations in this book are in the context of switches, many of the fundamenta

  20. Switching dynamics of TaOx-based threshold switching devices

    Science.gov (United States)

    Goodwill, Jonathan M.; Gala, Darshil K.; Bain, James A.; Skowronski, Marek

    2018-03-01

    Bi-stable volatile switching devices are being used as access devices in solid-state memory arrays and as the active part of compact oscillators. Such structures exhibit two stable states of resistance and switch between them at a critical value of voltage or current. A typical resistance transient under a constant amplitude voltage pulse starts with a slow decrease followed by a rapid drop and leveling off at a low steady state value. This behavior prompted the interpretation of initial delay and fast transition as due to two different processes. Here, we show that the entire transient including incubation time, transition time, and the final resistance values in TaOx-based switching can be explained by one process, namely, Joule heating with the rapid transition due to the thermal runaway. The time, which is required for the device in the conducting state to relax back to the stable high resistance one, is also consistent with the proposed mechanism.

  1. IGBT: a solid state switch

    International Nuclear Information System (INIS)

    Chatroux, D.; Maury, J.; Hennevin, B.

    1993-01-01

    A Copper Vapour Laser Power Supply has been designed using a solid state switch consisting in eighteen Isolated Gate Bipolar Transistors (IGBT), -1200 volts, 400 Amps, each-in parallel. This paper presents the Isolated Gate Bipolar Transistor (IGBTs) replaced in the Power Electronic components evolution, and describes the IGBT conduction mechanism, presents the parallel association of IGBTs, and studies the application of these components to a Copper Vapour Laser Power Supply. The storage capacitor voltage is 820 volts, the peak current of the solid state switch is 17.000 Amps. The switch is connected on the primary of a step-up transformer, followed by a magnetic modulator. The reset of the magnetic modulator is provided by part of the laser reflected energy with a patented circuit. The charging circuit is a resonant circuit with a charge controlled by an IGBT switch. When the switch is open, the inductance energy is free-wheeled by an additional winding and does not extend the charging phase of the storage capacitor. The design allows the storage capacitor voltage to be very well regulated. This circuit is also patented. The electric pulse in the laser has 30.000 Volt peak voltage, 2000 Amp peak current, and is 200 nanoseconds long, for a 200 Watt optical power Copper Vapour Laser

  2. CMOS integrated switching power converters

    CERN Document Server

    Villar-Pique, Gerard

    2011-01-01

    This book describes the structured design and optimization of efficient, energy processing integrated circuits. The approach is multidisciplinary, covering the monolithic integration of IC design techniques, power electronics and control theory. In particular, this book enables readers to conceive, synthesize, design and implement integrated circuits with high-density high-efficiency on-chip switching power regulators. Topics covered encompass the structured design of the on-chip power supply, efficiency optimization, IC-compatible power inductors and capacitors, power MOSFET switches and effi

  3. All-fiber polarization switch

    Science.gov (United States)

    Knape, Harald; Margulis, Walter

    2007-03-01

    We report an all-fiber polarization switch made out of silica-based microstructured fiber suitable for Q-switching all-fiber lasers. Nanosecond high-voltage pulses are used to heat and expand an internal electrode to cause λ/2-polarization rotation in less than 10 ns for 1.5 μm light. The 10 cm long component has an experimentally measured optical insertion loss of 0.2 dB and a 0-10 kHz repetition frequency capacity and has been durability tested for more than 109 pulses.

  4. A level switch with a sound tube

    OpenAIRE

    赤池, 誠規

    2017-01-01

    Level switches are sensor with an electrical contact output at a specific liquid, powder or bulk level. Most of traditional level switches are not suitable for harsh environments. The level switch in this study connects a loudspeaker on top end of the sound tube. When liquid, powder or bulk closes bottom end of the sound tube, the level switch turns on. The level switch is suitable for harsh environments and easy to install. The aim of this study is to propose a level switch with a sound tube...

  5. Industry switching in developing countries

    DEFF Research Database (Denmark)

    Newman, Carol; Rand, John; Tarp, Finn

    2013-01-01

    Firm turnover (i.e., firm entry and exit) is a well-recognized source of sector-level productivity growth. In contrast, the role and importance of firms that switch activities from one sector to another is not well understood. Firm switchers are likely to be unique, differing from both newly esta...

  6. Nanoscale organic ferroelectric resistive switches

    NARCIS (Netherlands)

    Khikhlovskyi, V.; Wang, R.; Breemen, A.J.J.M. van; Gelinck, G.H.; Janssen, R.A.J.; Kemerink, M.

    2014-01-01

    Organic ferroelectric resistive switches function by grace of nanoscale phase separation in a blend of a semiconducting and a ferroelectric polymer that is sandwiched between metallic electrodes. In this work, various scanning probe techniques are combined with numerical modeling to unravel their

  7. Design of convergent switched systems

    NARCIS (Netherlands)

    Berg, van den R.A.; Pogromsky, A.Y.; Leonov, G.A.; Rooda, J.E.; Pettersen, K.Y.; Gravdahl, J.T.; Nijmeijer, H.

    2006-01-01

    In this paper we deal with the problem of rendering hybrid/nonlinear systems into convergent closed-loop systems by means of a feedback law or switching rules. We illustrate our approach to this problem by means of two examples: the anti-windup design for a marginally stable system with input

  8. Incorrect predictions reduce switch costs.

    Science.gov (United States)

    Kleinsorge, Thomas; Scheil, Juliane

    2015-07-01

    In three experiments, we combined two sources of conflict within a modified task-switching procedure. The first source of conflict was the one inherent in any task switching situation, namely the conflict between a task set activated by the recent performance of another task and the task set needed to perform the actually relevant task. The second source of conflict was induced by requiring participants to guess aspects of the upcoming task (Exps. 1 & 2: task identity; Exp. 3: position of task precue). In case of an incorrect guess, a conflict accrues between the representation of the guessed task and the actually relevant task. In Experiments 1 and 2, incorrect guesses led to an overall increase of reaction times and error rates, but they reduced task switch costs compared to conditions in which participants predicted the correct task. In Experiment 3, incorrect guesses resulted in faster performance overall and to a selective decrease of reaction times in task switch trials when the cue-target interval was long. We interpret these findings in terms of an enhanced level of controlled processing induced by a combination of two sources of conflict converging upon the same target of cognitive control. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Multiuser switched diversity scheduling schemes

    KAUST Repository

    Shaqfeh, Mohammad; Alnuweiri, Hussein M.; Alouini, Mohamed-Slim

    2012-01-01

    Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

  10. Stability of Randomly Switched Diffusions

    DEFF Research Database (Denmark)

    Schiøler, Henrik; Leth, John-Josef; Gholami, Mehdi

    2012-01-01

    This paper provides a sufficient criterion for ε-moment stability (boundedness) and ergodicity for a class of systems comprising a finite set of diffusions among which switching is governed by a continuous time Markov chain. Stability/instability properties for each separate subsystem are assumed...

  11. Industry Switching in Developing Countries

    DEFF Research Database (Denmark)

    Newman, Carol; Rand, John; Tarp, Finn

    Firm turnover (i.e. firm entry and exit) is a well-recognized source of sectorlevel productivity growth across developing and developed countries. In contrast, the role and importance of firms switching activities from one sector to another is little understood. Firm switchers are likely...

  12. Charge transport through molecular switches

    International Nuclear Information System (INIS)

    Jan van der Molen, Sense; Liljeroth, Peter

    2010-01-01

    We review the fascinating research on charge transport through switchable molecules. In the past decade, detailed investigations have been performed on a great variety of molecular switches, including mechanically interlocked switches (rotaxanes and catenanes), redox-active molecules and photochromic switches (e.g. azobenzenes and diarylethenes). To probe these molecules, both individually and in self-assembled monolayers (SAMs), a broad set of methods have been developed. These range from low temperature scanning tunneling microscopy (STM) via two-terminal break junctions to larger scale SAM-based devices. It is generally found that the electronic coupling between molecules and electrodes has a profound influence on the properties of such molecular junctions. For example, an intrinsically switchable molecule may lose its functionality after it is contacted. Vice versa, switchable two-terminal devices may be created using passive molecules ('extrinsic switching'). Developing a detailed understanding of the relation between coupling and switchability will be of key importance for both future research and technology. (topical review)

  13. Charge transport through molecular switches

    Energy Technology Data Exchange (ETDEWEB)

    Jan van der Molen, Sense [Kamerlingh Onnes Laboratorium, Leiden University, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Liljeroth, Peter, E-mail: molen@physics.leidenuniv.n [Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, University of Utrecht, PO Box 80000, 3508 TA Utrecht (Netherlands)

    2010-04-07

    We review the fascinating research on charge transport through switchable molecules. In the past decade, detailed investigations have been performed on a great variety of molecular switches, including mechanically interlocked switches (rotaxanes and catenanes), redox-active molecules and photochromic switches (e.g. azobenzenes and diarylethenes). To probe these molecules, both individually and in self-assembled monolayers (SAMs), a broad set of methods have been developed. These range from low temperature scanning tunneling microscopy (STM) via two-terminal break junctions to larger scale SAM-based devices. It is generally found that the electronic coupling between molecules and electrodes has a profound influence on the properties of such molecular junctions. For example, an intrinsically switchable molecule may lose its functionality after it is contacted. Vice versa, switchable two-terminal devices may be created using passive molecules ('extrinsic switching'). Developing a detailed understanding of the relation between coupling and switchability will be of key importance for both future research and technology. (topical review)

  14. Wide Bandgap Extrinsic Photoconductive Switches

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2013-07-03

    Semi-insulating Gallium Nitride, 4H and 6H Silicon Carbide are attractive materials for compact, high voltage, extrinsic, photoconductive switches due to their wide bandgap, high dark resistance, high critical electric field strength and high electron saturation velocity. These wide bandgap semiconductors are made semi-insulating by the addition of vanadium (4H and 6HSiC) and iron (2H-GaN) impurities that form deep acceptors. These deep acceptors trap electrons donated from shallow donor impurities. The electrons can be optically excited from these deep acceptor levels into the conduction band to transition the wide bandgap semiconductor materials from a semi-insulating to a conducting state. Extrinsic photoconductive switches with opposing electrodes have been constructed using vanadium compensated 6H-SiC and iron compensated 2H-GaN. These extrinsic photoconductive switches were tested at high voltage and high power to determine if they could be successfully used as the closing switch in compact medical accelerators.

  15. The Atlas load protection switch

    CERN Document Server

    Davis, H A; Dorr, G; Martínez, M; Gribble, R F; Nielsen, K E; Pierce, D; Parsons, W M

    1999-01-01

    Atlas is a high-energy pulsed-power facility under development to study materials properties and hydrodynamics experiments under extreme conditions. Atlas will implode heavy liner loads (m~45 gm) with a peak current of 27-32 MA delivered in 4 mu s, and is energized by 96, 240 kV Marx generators storing a total of 23 MJ. A key design requirement for Atlas is obtaining useful data for 95601130f all loads installed on the machine. Materials response calculations show current from a prefire can damage the load requiring expensive and time consuming replacement. Therefore, we have incorporated a set of fast-acting mechanical switches in the Atlas design to reduce the probability of a prefire damaging the load. These switches, referred to as the load protection switches, short the load through a very low inductance path during system charge. Once the capacitors have reached full charge, the switches open on a time scale short compared to the bank charge time, allowing current to flow to the load when the trigger pu...

  16. Intrinsic nanofilamentation in resistive switching

    KAUST Repository

    Wu, Xing

    2013-03-15

    Resistive switching materials are promising candidates for nonvolatile data storage and reconfiguration of electronic applications. Intensive studies have been carried out on sandwiched metal-insulator-metal structures to achieve high density on-chip circuitry and non-volatile memory storage. Here, we provide insight into the mechanisms that govern highly reproducible controlled resistive switching via a nanofilament by using an asymmetric metal-insulator-semiconductor structure. In-situ transmission electron microscopy is used to study in real-time the physical structure and analyze the chemical composition of the nanofilament dynamically during resistive switching. Electrical stressing using an external voltage was applied by a tungsten tip to the nanosized devices having hafnium oxide (HfO2) as the insulator layer. The formation and rupture of the nanofilaments result in up to three orders of magnitude change in the current flowing through the dielectric during the switching event. Oxygen vacancies and metal atoms from the anode constitute the chemistry of the nanofilament.

  17. Multiuser switched diversity scheduling schemes

    KAUST Repository

    Shaqfeh, Mohammad

    2012-09-01

    Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

  18. High voltage MOSFET switching circuit

    Science.gov (United States)

    McEwan, Thomas E.

    1994-01-01

    The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET.

  19. Switch-connected HyperX network

    Science.gov (United States)

    Chen, Dong; Heidelberger, Philip

    2018-02-13

    A network system includes a plurality of sub-network planes and global switches. The sub-network planes have a same network topology as each other. Each of the sub-network planes includes edge switches. Each of the edge switches has N ports. Each of the global switches is configured to connect a group of edge switches at a same location in the sub-network planes. In each of the sub-network planes, some of the N ports of each of the edge switches are connected to end nodes, and others of the N ports are connected to other edge switches in the same sub-network plane, other of the N ports are connected to at least one of the global switches.

  20. Isolated converter with synchronized switching leg

    NARCIS (Netherlands)

    2003-01-01

    An amplification device is disclosed providing a way of integrating a switch mode power supply and a class D amplifier (switch mode amplifier). This results in the usage of basically one magnetic component (1), one major energy storage element (4) and switches (20, 30) that are controlled in such a

  1. Mechanism of single atom switch on silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Thirstrup, C.

    1998-01-01

    We demonstrate single atom switch on silicon which operates by displacement of a hydrogen atom on the silicon (100) surface at room temperature. We find two principal effects by which the switch is controlled: a pronounced maximum of the switching probability as function of sample bias...

  2. A CW Gunn diode bistable switching element.

    Science.gov (United States)

    Hurtado, M.; Rosenbaum, F. J.

    1972-01-01

    Experiments with a current-controlled bistable switching element using a CW Gunn diode are reported. Switching rates of the order of 10 MHz have been obtained. Switching is initiated by current pulses of short duration (5-10 ns). Rise times of the order of several nanoseconds could be obtained.

  3. A gain-coefficient switched Alexandrite laser

    International Nuclear Information System (INIS)

    Lee, Chris J; Van der Slot, Peter J M; Boller, Klaus-J

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

  4. 47 CFR 69.106 - Local switching.

    Science.gov (United States)

    2010-10-01

    ... foreign services that use local exchange switching facilities. (c) If end users of an interstate or... local exchange carriers shall establish rate elements for local switching as follows: (1) Price cap... use local exchange switching facilities for the provision of interstate or foreign services. The...

  5. Caffeine improves anticipatory processes in task switching

    NARCIS (Netherlands)

    Tieges, Zoe; Snel, Jan; Kok, Albert; Wijnen, Jasper G.; Lorist, Monicque M.; Ridderinkhof, K. Richard

    We studied the effects of moderate amounts of caffeine on task switching and task maintenance using mixed-task (AABB) blocks, in which participants alternated predictably between two tasks, and single-task (AAAA, BBBB) blocks. Switch costs refer to longer reaction times (RT) on task switch trials

  6. Bootstrapped Low-Voltage Analog Switches

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1999-01-01

    Novel low-voltage constant-impedance analog switch circuits are proposed. The switch element is a single MOSFET, and constant-impedance operation is obtained using simple circuits to adjust the gate and bulk voltages relative to the switched signal. Low-voltage (1-volt) operation is made feasible...

  7. Control and synchronisation in switched arrival systems

    NARCIS (Netherlands)

    Rem, B.; Armbruster, H.D.

    2003-01-01

    A chaotic model of a production flow called the switched arrival system is extended to include switching times and maintenance. The probability distribution of the chaotic return times is calculated. Scheduling maintenance, loss of production due to switching, and control of the chaotic dynamics is

  8. Optimization of multi-branch switched diversity systems

    KAUST Repository

    Nam, Haewoon; Alouini, Mohamed-Slim

    2009-01-01

    A performance optimization based on the optimal switching threshold(s) for a multi-branch switched diversity system is discussed in this paper. For the conventional multi-branch switched diversity system with a single switching threshold

  9. Electronic logic to enhance switch reliability in detecting openings and closures of redundant switches

    Science.gov (United States)

    Cooper, James A.

    1986-01-01

    A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and failsafe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.

  10. Large aperture optical switching devices

    International Nuclear Information System (INIS)

    Goldhar, J.; Henesian, M.A.

    1983-01-01

    We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs

  11. Shape memory thermal conduction switch

    Science.gov (United States)

    Vaidyanathan, Rajan (Inventor); Krishnan, Vinu (Inventor); Notardonato, William U. (Inventor)

    2010-01-01

    A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

  12. Negation switching invariant signed graphs

    Directory of Open Access Journals (Sweden)

    Deepa Sinha

    2014-04-01

    Full Text Available A signed graph (or, $sigraph$ in short is a graph G in which each edge x carries a value $\\sigma(x \\in \\{-, +\\}$ called its sign. Given a sigraph S, the negation $\\eta(S$ of the sigraph S is a sigraph obtained from S by reversing the sign of every edge of S. Two sigraphs $S_{1}$ and $S_{2}$ on the same underlying graph are switching equivalent if it is possible to assign signs `+' (`plus' or `-' (`minus' to vertices of $S_{1}$ such that by reversing the sign of each of its edges that has received opposite signs at its ends, one obtains $S_{2}$. In this paper, we characterize sigraphs which are negation switching invariant and also see for what sigraphs, S and $\\eta (S$ are signed isomorphic.

  13. Switch for Good Community Program

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Tabitha [Balfour Beatty Military Housing Management LLC, Newtown Square, PA (United States); Amran, Martha [WattzOn, Inc., Mountain View, CA (United States)

    2013-11-19

    Switch4Good is an energy-savings program that helps residents reduce consumption from behavior changes; it was co-developed by Balfour Beatty Military Housing Management (BB) and WattzOn in Phase I of this grant. The program was offered at 11 Navy bases. Three customer engagement strategies were evaluated, and it was found that Digital Nudges (a combination of monthly consumption statements with frequent messaging via text or email) was most cost-effective. The program was delivered on-time and on-budget, and its success is based on the teamwork of local BB staff and the WattzOn team. The following graphic shows Switch4Good “by the numbers”, e.g. the scale of operations achieved during Phase I.

  14. Pulsed laser triggered high speed microfluidic switch

    Science.gov (United States)

    Wu, Ting-Hsiang; Gao, Lanyu; Chen, Yue; Wei, Kenneth; Chiou, Pei-Yu

    2008-10-01

    We report a high-speed microfluidic switch capable of achieving a switching time of 10 μs. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices.

  15. Secure videoconferencing equipment switching system and method

    Science.gov (United States)

    Hansen, Michael E [Livermore, CA

    2009-01-13

    A switching system and method are provided to facilitate use of videoconference facilities over a plurality of security levels. The system includes a switch coupled to a plurality of codecs and communication networks. Audio/Visual peripheral components are connected to the switch. The switch couples control and data signals between the Audio/Visual peripheral components and one but nor both of the plurality of codecs. The switch additionally couples communication networks of the appropriate security level to each of the codecs. In this manner, a videoconferencing facility is provided for use on both secure and non-secure networks.

  16. Switching strategies to optimize search

    International Nuclear Information System (INIS)

    Shlesinger, Michael F

    2016-01-01

    Search strategies are explored when the search time is fixed, success is probabilistic and the estimate for success can diminish with time if there is not a successful result. Under the time constraint the problem is to find the optimal time to switch a search strategy or search location. Several variables are taken into account, including cost, gain, rate of success if a target is present and the probability that a target is present. (paper: interdisciplinary statistical mechanics)

  17. Correlated randomness and switching phenomena

    Science.gov (United States)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

    2010-08-01

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

  18. Fast superconducting magnetic field switch

    Science.gov (United States)

    Goren, Yehuda; Mahale, Narayan K.

    1996-01-01

    The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles.

  19. Fast superconducting magnetic field switch

    International Nuclear Information System (INIS)

    Goren, Y.; Mahale, N.K.

    1996-01-01

    The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. 6 figs

  20. Coating possibilities for magnetic switches

    International Nuclear Information System (INIS)

    Sharp, D.J.; Harjes, H.C.; Mann, G.A.; Morgan, F.A.

    1990-01-01

    High average power magnetic pulse compression systems are now being considered for use in several applications such as the High Power Radiation Source (HiPoRS) project. Such systems will require high reliability magnetic switches (saturable inductors) that are very efficient and have long lifetimes. One of the weakest components in magnetic switches is their interlaminar insulation. Considerations related to dielectric breakdown, thermal management of compact designs, and economical approaches for achieving these needs must be addressed. Various dielectric insulation and coating materials have been applied to Metglas foil in an attempt to solve the complex technical and practical problems associated with large magnetic switch structures. This work reports various needs, studies, results, and proposals in selecting and evaluating continuous coating approaches for magnetic foil. Techniques such as electrophoretic polymer deposition and surface chemical oxidation are discussed. We also propose continuous photofabrication processes for applying dielectric ribs or spacers to the foil which permit circulation of dielectric liquids for cooling during repetitive operation. 10 refs., 8 figs., 11 tabs

  1. Analytical Performance Evaluation of Different Switch Solutions

    Directory of Open Access Journals (Sweden)

    Francisco Sans

    2013-01-01

    Full Text Available The virtualization of the network access layer has opened new doors in how we perceive networks. With this virtualization of the network, it is possible to transform a regular PC with several network interface cards into a switch. PC-based switches are becoming an alternative to off-the-shelf switches, since they are cheaper. For this reason, it is important to evaluate the performance of PC-based switches. In this paper, we present a performance evaluation of two PC-based switches, using Open vSwitch and LiSA, and compare their performance with an off-the-shelf Cisco switch. The RTT, throughput, and fairness for UDP are measured for both Ethernet and Fast Ethernet technologies. From this research, we can conclude that the Cisco switch presents the best performance, and both PC-based switches have similar performance. Between Open vSwitch and LiSA, Open vSwitch represents a better choice since it has more features and is currently actively developed.

  2. Streamer model for high voltage water switches

    International Nuclear Information System (INIS)

    Sazama, F.J.; Kenyon, V.L. III

    1979-01-01

    An electrical switch model for high voltage water switches has been developed which predicts streamer-switching effects that correlate well with water-switch data from Casino over the past four years and with switch data from recent Aurora/AMP experiments. Preclosure rounding and postclosure resistive damping of pulseforming line voltage waveforms are explained in terms of spatially-extensive, capacitive-coupling of the conducting streamers as they propagate across the gap and in terms of time-dependent streamer resistance and inductance. The arc resistance of the Casino water switch and of a gas switch under test on Casino was determined by computer fit to be 0.5 +- 0.1 ohms and 0.3 +- 0.06 ohms respectively, during the time of peak current in the power pulse. Energy lost in the water switch during the first pulse is 18% of that stored in the pulseforming line while similar energy lost in the gas switch is 11%. The model is described, computer transient analyses are compared with observed water and gas switch data and the results - switch resistance, inductance and energy loss during the primary power pulse - are presented

  3. Optical Multidimensional Switching for Data Center Networks

    DEFF Research Database (Denmark)

    Kamchevska, Valerija

    2017-01-01

    . Software controlled switching using an on-chip integrated fiber switch is demonstrated and enabling of additional network functionalities such as multicast and optical grooming is experimentally confirmed. Altogether this work demonstrates the potential of optical switching technologies...... for the purpose of deploying optical switching within the network. First, the Hi-Ring data center architecture is proposed. It is based on optical multidimensional switching nodes that provide switching in hierarchically layered space, wavelength and time domain. The performance of the Hi-Ring architecture...... is evaluated experimentally and successful switching of both high capacity wavelength connections and time-shared subwavelengthconnections is demonstrated. Error-free performance is also achieved when transmitting 7 Tbit/s using multicore fiber, confirming the ability to scale the network. Moreover...

  4. Pinning Synchronization of Switched Complex Dynamical Networks

    Directory of Open Access Journals (Sweden)

    Liming Du

    2015-01-01

    Full Text Available Network topology and node dynamics play a key role in forming synchronization of complex networks. Unfortunately there is no effective synchronization criterion for pinning synchronization of complex dynamical networks with switching topology. In this paper, pinning synchronization of complex dynamical networks with switching topology is studied. Two basic problems are considered: one is pinning synchronization of switched complex networks under arbitrary switching; the other is pinning synchronization of switched complex networks by design of switching when synchronization cannot achieved by using any individual connection topology alone. For the two problems, common Lyapunov function method and single Lyapunov function method are used respectively, some global synchronization criteria are proposed and the designed switching law is given. Finally, simulation results verify the validity of the results.

  5. Synchronization in complex networks with switching topology

    International Nuclear Information System (INIS)

    Wang, Lei; Wang, Qing-guo

    2011-01-01

    This Letter investigates synchronization issues of complex dynamical networks with switching topology. By constructing a common Lyapunov function, we show that local and global synchronization for a linearly coupled network with switching topology can be evaluated by the time average of second smallest eigenvalues corresponding to the Laplacians of switching topology. This result is quite powerful and can be further used to explore various switching cases for complex dynamical networks. Numerical simulations illustrate the effectiveness of the obtained results in the end. -- Highlights: → Synchronization of complex networks with switching topology is investigated. → A common Lyapunov function is established for synchronization of switching network. → The common Lyapunov function is not necessary to monotonically decrease with time. → Synchronization is determined by the second smallest eigenvalue of its Laplacian. → Synchronization criterion can be used to investigate various switching cases.

  6. Energy storage, compression, and switching. Vol. 2

    International Nuclear Information System (INIS)

    Nardi, V.; Bostick, W.H.; Sahlin, H.

    1983-01-01

    This book is a compilation of papers presented at the Second International Conference on Energy Storage, Compression, and Switching, which was held in order to assemble active researchers with a major interest in plasma physics, electron beams, electric and magnetic energy storage systems, high voltage and high current switches, free-electron lasers, and pellet implosion plasma focus. Topics covered include: Slow systems: 50-60 Hz machinery, homopolar generators, slow capacitors, inductors, and solid state switches; Intermediate systems: fast capacitor banks; superconducting storage and switching; gas, vacuum, and dielectric switching; nonlinear (magnetic) switching; imploding liners capacitors; explosive generators; and fuses; and Fast systems: Marx, Blumlein, oil, water, and pressurized water dielectrics; switches; magnetic insulation; electron beams; and plasmas

  7. A circadian clock-regulated toggle switch explains AtGRP7 and AtGRP8 oscillations in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Christoph Schmal

    Full Text Available The circadian clock controls many physiological processes in higher plants and causes a large fraction of the genome to be expressed with a 24h rhythm. The transcripts encoding the RNA-binding proteins AtGRP7 (Arabidopsis thaliana Glycine Rich Protein 7 and AtGRP8 oscillate with evening peaks. The circadian clock components CCA1 and LHY negatively affect AtGRP7 expression at the level of transcription. AtGRP7 and AtGRP8, in turn, negatively auto-regulate and reciprocally cross-regulate post-transcriptionally: high protein levels promote the generation of an alternative splice form that is rapidly degraded. This clock-regulated feedback loop has been proposed to act as a molecular slave oscillator in clock output. While mathematical models describing the circadian core oscillator in Arabidopsis thaliana were introduced recently, we propose here the first model of a circadian slave oscillator. We define the slave oscillator in terms of ordinary differential equations and identify the model's parameters by an optimization procedure based on experimental results. The model successfully reproduces the pertinent experimental findings such as waveforms, phases, and half-lives of the time-dependent concentrations. Furthermore, we obtain insights into possible mechanisms underlying the observed experimental dynamics: the negative auto-regulation and reciprocal cross-regulation via alternative splicing could be responsible for the sharply peaking waveforms of the AtGRP7 and AtGRP8 mRNA. Moreover, our results suggest that the AtGRP8 transcript oscillations are subordinated to those of AtGRP7 due to a higher impact of AtGRP7 protein on alternative splicing of its own and of the AtGRP8 pre-mRNA compared to the impact of AtGRP8 protein. Importantly, a bifurcation analysis provides theoretical evidence that the slave oscillator could be a toggle switch, arising from the reciprocal cross-regulation at the post-transcriptional level. In view of this

  8. Structurally characterized 1,1,3,3-tetramethylguanidine solvated magnesium aryloxide complexes: [Mg(mu-OEt)(DBP)(H-TMG)]2, [Mg(mu-OBc)(DBP)(H-TMG)]2, [Mg(mu-TMBA)(DBP)(H-TMG)]2, [Mg(mu-DPP)(DBP)(H-TMG)]2, [Mg(BMP)2(H-TMG)2], [Mg(O-2,6-Ph2C6H3)2 (H-TMG)2].

    Science.gov (United States)

    Monegan, Jessie D; Bunge, Scott D

    2009-04-06

    The synthesis and structural characterization of several 1,1,3,3-tetramethylguanidine (H-TMG) solvated magnesium aryloxide complexes are reported. Bu(2)Mg was successfully reacted with H-TMG, HOC(6)H(3)(CMe(3))(2)-2,6 (H-DBP), and either ethanol, a carboxylic acid, or diphenyl phosphate in a 1:1 ratio to yield the corresponding [Mg(mu-L)(DBP)(H-TMG)](2) where L = OCH(2)CH(3) (OEt, 1), O(2)CC(CH(3))(3) (OBc, 2), O(2)C(C(6)H(2)-2,4,6-(CH(3))(3)) (TMBA, 3), or O(2)P(OC(6)H(5))(2) (DPP, 4). Bu(2)Mg was also reacted with two equivalents of H-TMG and HOC(6)H(3)(CMe(3))-2-(CH(3))-6 (BMP) or HO-2,6-Ph(2)C(6)H(3) to yield [Mg(BMP)(2)(H-TMG)(2)] (5) and [Mg(O-2,6-Ph(2)C(6)H(3))(2)(H-TMG)(2)] (6). Compounds 1-6 were characterized by single-crystal X-ray diffraction. Polymerization of l- and rac-lactide with 1 was found to generate polylactide (PLA). A discussion concerning the relevance of compounds 2 - 4 to the structure of Mg-activated phosphatase enzymes is also provided. The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, FT-IR spectroscopy, and (1)H, (13)C and (31)P NMR studies.

  9. Enhancement of resistive switching properties in Al2O3 bilayer-based atomic switches: multilevel resistive switching

    Science.gov (United States)

    Vishwanath, Sujaya Kumar; Woo, Hyunsuk; Jeon, Sanghun

    2018-06-01

    Atomic switches are considered to be building blocks for future non-volatile data storage and internet of things. However, obtaining device structures capable of ultrahigh density data storage, high endurance, and long data retention, and more importantly, understanding the switching mechanisms are still a challenge for atomic switches. Here, we achieved improved resistive switching performance in a bilayer structure containing aluminum oxide, with an oxygen-deficient oxide as the top switching layer and stoichiometric oxide as the bottom switching layer, using atomic layer deposition. This bilayer device showed a high on/off ratio (105) with better endurance (∼2000 cycles) and longer data retention (104 s) than single-oxide layers. In addition, depending on the compliance current, the bilayer device could be operated in four different resistance states. Furthermore, the depth profiles of the hourglass-shaped conductive filament of the bilayer device was observed by conductive atomic force microscopy.

  10. Radiation-sensitive switching circuits

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.H.; Cockshott, C.P.

    1976-03-16

    A radiation-sensitive switching circuit has a light emitting diode which supplies light to a photo-transistor, the light being interrupted from time to time. When the photo-transistor is illuminated, current builds up and when this current reaches a predetermined value, a trigger circuit changes state. The peak output of the photo-transistor is measured and the trigger circuit is arranged to change state when the output of the device is a set proportion of the peak output, so as to allow for aging of the components. The circuit is designed to control the ignition system in an automobile engine.

  11. Radiation-sensitive switching circuits

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.H.; Cockshott, C.P.

    1976-03-16

    A radiation-sensitive switching circuit includes a light emitting diode which from time to time illuminates a photo-transistor, the photo-transistor serving when its output reaches a predetermined value to operate a trigger circuit. In order to allow for aging of the components, the current flow through the diode is increased when the output from the transistor falls below a known level. Conveniently, this is achieved by having a transistor in parallel with the diode, and turning the transistor off when the output from the phototransistor becomes too low. The circuit is designed to control the ignition system in an automobile engine.

  12. Know-How on design of switching regulator

    International Nuclear Information System (INIS)

    1985-08-01

    This book introduces switching regulator from base to application, which deals with fundamentals of switching regulator such as the reason of boom about switching regulator, understanding simple circuit without electric transformer and decision of circuit type with input voltage and output voltage, configuration and characteristic of switching regulator, a concrete design of switching regulator, pulse width control circuit and protection circuit, concrete circuit examples of switching power and the point of switching regulator.

  13. Stateless multicast switching in software defined networks

    OpenAIRE

    Reed, Martin J.; Al-Naday, Mays; Thomos, Nikolaos; Trossen, Dirk; Petropoulos, George; Spirou, Spiros

    2016-01-01

    Multicast data delivery can significantly reduce traffic in operators' networks, but has been limited in deployment due to concerns such as the scalability of state management. This paper shows how multicast can be implemented in contemporary software defined networking (SDN) switches, with less state than existing unicast switching strategies, by utilising a Bloom Filter (BF) based switching technique. Furthermore, the proposed mechanism uses only proactive rule insertion, and thus, is not l...

  14. AN ANALYTICAL STUDY OF SWITCHING TRACTION MOTORS

    Directory of Open Access Journals (Sweden)

    V. M. Bezruchenko

    2010-03-01

    Full Text Available The analytical study of switching of the tractive engines of electric locomotives is conducted. It is found that the obtained curves of change of current of the sections commuted correspond to the theory of average rectilinear switching. By means of the proposed method it is possible on the stage of design of tractive engines to forecast the quality of switching and to correct it timely.

  15. Monitoring Mellanox Infiniband SX6036 switches

    CERN Document Server

    Agapiou, Marinos

    2017-01-01

    The SX6036 switches addressed by my project, are part of a fully non-blocking fat-tree cluster consisting of 72 servers and 6 Mellanox SX6036 Infiniband switches. My project is about retrieving the appropriate metrics from the Infiniband switch cluster, ingesting the data to Collectd and after my data are being transfered to CERN Database, they are being visualized via Grafana Dashboards.

  16. Optical switches based on surface plasmons

    International Nuclear Information System (INIS)

    Chen Cong; Wang Pei; Yuan Guanghui; Wang Xiaolei; Min Changjun; Deng Yan; Lu Yonghua; Ming Hai

    2008-01-01

    Great attention is being paid to surface plasmons (SPs) because of their potential applications in sensors, data storage and bio-photonics. Recently, more and more optical switches based on surface plasmon effects have been demonstrated either by simulation or experimentally. This article describes the principles, advantages and disadvantages of various types of optical switches based on SPs, in particular the all-optical switches. (authors)

  17. A new switched power linac structure

    International Nuclear Information System (INIS)

    Villa, F.

    1989-03-01

    A new pulse power structure has been described that utilizes an easily accessible rectilinear switch. The new structure is more ''forgiving'' (as far as risetime is concerned) than the radial line transformer, and contains fewer switching structures/unit length. The combination of the new structure with the switch proposed seems to offer interesting possibilities for a future linear collider. 13 refs., 6 figs., 2 tabs

  18. Switching induced oscillations in the logistic map

    Energy Technology Data Exchange (ETDEWEB)

    Maier, Makisha P.S. [Department of Chemistry, Williams College, Williamstown, MA 01267 (United States); Peacock-Lopez, Enrique, E-mail: epeacock@williams.ed [Department of Chemistry, Williams College, Williamstown, MA 01267 (United States)

    2010-02-08

    In ecological modeling, seasonality can be represented as a switching between different environmental conditions. This switching strategy can be related to the so-called Parrondian games, where the alternation of two losing games yield a winning game. Hence we can consider two dynamics that, by themselves, yield undesirable behaviors, but when alternated yield a desirable oscillatory behavior. In this case, we also consider a noisy switching strategy and find that the desirable oscillatory behavior prevails.

  19. Ultrafast pulse generation in photoconductive switches

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Dykaar, D. R.

    1996-01-01

    Carrier and field dynamics in photoconductive switches are investigated by electrooptic sampling and voltage-dependent reflectivity measurements. We show that the nonuniform field distribution due to the two-dimensional nature of coplanar photoconductive switches, in combination with the large di...... difference in the mobilities of holes and electrons, determine the pronounced polarity dependence. Our measurements indicate that the pulse generation mechanism is a rapid voltage breakdown across the photoconductive switch and not a local field breakdown...

  20. A magnetically switched kicker for proton extraction

    International Nuclear Information System (INIS)

    Dinkel, J.; Biggs, J.

    1989-03-01

    The application of magnetic current amplification and switching techniques to the generation of precise high current pulses for switching magnets is described. The square loop characteristic of Metglas tape wound cores at high excitation levels provides excellent switching characteristics for microsecond pulses. The rugged and passive nature of this type pulser makes it possible to locate the final stages of amplification at the load for maximum efficiency. 12 refs., 8 figs

  1. Atomic battery with beam switching

    International Nuclear Information System (INIS)

    Edling, E.A.; McKenna, R.P.; Peterick, E.Th. Jr.; Trexler, F.D.

    1984-01-01

    An electric power generating apparatus that is powered primarily by the emission of electrically charged particles from radio-active materials enclosed in an evacuated vessel of glass or the like. An arrangement of reflecting electrodes causes a beam of particles to switch back and forth at a high frequency between two collecting electrodes that are connected to a resonating tuned primary circuit consisting of an inductor with resonating capacitor. The reflecting electrodes are energized in the proper phase relationship to the collecting electrodes to insure sustained oscillation by means of a secondary winding coupled inductively to the primary winding and connected to the reflecting electrodes. Power may be drawn from the circuit at a stepped down voltage from a power take-off winding that is coupled to the primary winding. The disclosure also describes a collecting electrode arrangement consisting of multiple spatially separated electrodes which together serve to capture a maximum of the available particle energy. A self-starting arrangement for start of oscillations is described. A specially adapted version of the invention utilizes two complementary beams of oppositely charged particles which are switched alternatingly between the collecting electrodes

  2. Atomic crystals resistive switching memory

    International Nuclear Information System (INIS)

    Liu Chunsen; Zhang David Wei; Zhou Peng

    2017-01-01

    Facing the growing data storage and computing demands, a high accessing speed memory with low power and non-volatile character is urgently needed. Resistive access random memory with 4F 2 cell size, switching in sub-nanosecond, cycling endurances of over 10 12 cycles, and information retention exceeding 10 years, is considered as promising next-generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory. (topical reviews)

  3. Heat switch technology for cryogenic thermal management

    Science.gov (United States)

    Shu, Q. S.; Demko, J. A.; E Fesmire, J.

    2017-12-01

    Systematic review is given of development of novel heat switches at cryogenic temperatures that alternatively provide high thermal connection or ideal thermal isolation to the cold mass. These cryogenic heat switches are widely applied in a variety of unique superconducting systems and critical space applications. The following types of heat switch devices are discussed: 1) magnetic levitation suspension, 2) shape memory alloys, 3) differential thermal expansion, 4) helium or hydrogen gap-gap, 5) superconducting, 6) piezoelectric, 7) cryogenic diode, 8) magneto-resistive, and 9) mechanical demountable connections. Advantages and limitations of different cryogenic heat switches are examined along with the outlook for future thermal management solutions in materials and cryogenic designs.

  4. Stochastic multistep polarization switching in ferroelectrics

    Science.gov (United States)

    Genenko, Y. A.; Khachaturyan, R.; Schultheiß, J.; Ossipov, A.; Daniels, J. E.; Koruza, J.

    2018-04-01

    Consecutive stochastic 90° polarization switching events, clearly resolved in recent experiments, are described by a nucleation and growth multistep model. It extends the classical Kolmogorov-Avrami-Ishibashi approach and includes possible consecutive 90°- and parallel 180° switching events. The model predicts the results of simultaneous time-resolved macroscopic measurements of polarization and strain, performed on a tetragonal Pb (Zr ,Ti ) O3 ceramic in a wide range of electric fields over a time domain of seven orders of magnitude. It allows the determination of the fractions of individual switching processes, their characteristic switching times, activation fields, and respective Avrami indices.

  5. The increased importance of sector switching

    DEFF Research Database (Denmark)

    Frederiksen, Anders; Hansen, Jesper Rosenberg

    2017-01-01

    Sector switching is an important phenomenon that casts light on public–private differences. Yet our knowledge about its prevalence and trends is limited. We study sector switching using unique Danish register-based employer–employee data covering more than 25 years. We find that sector switching...... constitutes 18.5% of all job-to-job mobility, and the trend is increasing both from public to private and from private to public. Sector switching is also generally increasing for middle managers, but for administrative professionals only the flows from private to public increase and for top managers only...... the flows from public to private increase....

  6. Wireless Nanoionic-Based Radio Frequency Switch

    Science.gov (United States)

    Nessel, James A. (Inventor); Miranda, Felix A (Inventor)

    2017-01-01

    A nanoionic switch connected to one or more rectenna modules is disclosed. The rectenna module is configured to receive a wireless signal and apply a first bias to change a state of the nanoionic switch from a first state to a second state. The rectenna module can receive a second wireless signal and apply a second bias to change the nanoionic switch from the second state back to the first state. The first bias is generally opposite of the first bias. The rectenna module accordingly permits operation of the nanoionic switch without onboard power.

  7. Low-Voltage Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Bidari, E.; Keskin, M.; Maloberti, F.

    1999-01-01

    Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications.......Switched-capacitor stages are described which can function with very low (typically 1 V) supply voltages, without using voltage boosting or switched op-amps. Simulations indicate that high performance may be achieved using these circuits in filter or data converter applications....

  8. Clocking Scheme for Switched-Capacitor Circuits

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1998-01-01

    A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed.......A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed....

  9. Simplified design of switching power supplies

    CERN Document Server

    Lenk, John

    1995-01-01

    * Describes the operation of each circuit in detail * Examines a wide selection of external components that modify the IC package characteristics * Provides hands-on, essential information for designing a switching power supply Simplified Design of Switching Power Supplies is an all-inclusive, one-stop guide to switching power-supply design. Step-by-step instructions and diagrams render this book essential for the student and the experimenter, as well as the design professional. Simplified Design of Switching Power Supplies concentrates on the use of IC regulators. All popular forms of swit

  10. Demonstration of Ultra-Fast Switching in Nano metallic Resistive Switching Memory Devices

    International Nuclear Information System (INIS)

    Yang, Y.

    2016-01-01

    Interdependency of switching voltage and time creates a dilemma/obstacle for most resistive switching memories, which indicates low switching voltage and ultra-fast switching time cannot be simultaneously achieved. In this paper, an ultra-fast (sub-100 ns) yet low switching voltage resistive switching memory device (“nano metallic ReRAM”) was demonstrated. Experimental switching voltage is found independent of pulse width (intrinsic device property) when the pulse is long but shows abrupt time dependence (“cliff”) as pulse width approaches characteristic RC time of memory device (extrinsic device property). Both experiment and simulation show that the onset of cliff behavior is dependent on physical device size and parasitic resistance, which is expected to diminish as technology nodes shrink down. We believe this study provides solid evidence that nano metallic resistive switching memory can be reliably operated at low voltage and ultra-fast regime, thus beneficial to future memory technology.

  11. The Application of High Temperature Superconducting Materials to Power Switches

    CERN Document Server

    March, S A; Ballarino, A

    2009-01-01

    Superconducting switches may find application in superconducting magnet systems that require energy extraction. Such superconducting switches could be bypass-switches that are operated in conjunction with a parallel resistor or dump-switches where all of the energy is dissipated in the switch itself. Bypass-switches are more suited to higher energy circuits as a portion of the energy can be dissipated in the external dump resistor. Dump- switches require less material and triggering energy as a lower switch resistance is needed to achieve the required total dump resistance. Both superconducting bypass-switches and superconducting dump-switches can be ther- mally activated. Switching times that are comparable to those obtained with mechanical bypass-switch systems can be achieved using a co-wound heater that is powered by a ca- pacitor discharge. Switches that have fast thermal diffusion times through the insulation can be modelled as a lumped system whereas those with slow thermal diffusion times were modelle...

  12. Optimal control of switching time in switched stochastic systems with multi-switching times and different costs

    Science.gov (United States)

    Liu, Xiaomei; Li, Shengtao; Zhang, Kanjian

    2017-08-01

    In this paper, we solve an optimal control problem for a class of time-invariant switched stochastic systems with multi-switching times, where the objective is to minimise a cost functional with different costs defined on the states. In particular, we focus on problems in which a pre-specified sequence of active subsystems is given and the switching times are the only control variables. Based on the calculus of variation, we derive the gradient of the cost functional with respect to the switching times on an especially simple form, which can be directly used in gradient descent algorithms to locate the optimal switching instants. Finally, a numerical example is given, highlighting the validity of the proposed methodology.

  13. Sequential Effects in Deduction: Cost of Inference Switch

    Science.gov (United States)

    Milan, Emilio G.; Moreno-Rios, Sergio; Espino, Orlando; Santamaria, Carlos; Gonzalez-Hernandez, Antonio

    2010-01-01

    The task-switch paradigm has helped psychologists gain insight into the processes involved in changing from one activity to another. The literature has yielded consistent results about switch cost reconfiguration (abrupt offset in regular task-switch vs. gradual reduction in random task-switch; endogenous and exogenous components of switch cost;…

  14. Rotation Impact of Reed Switch

    International Nuclear Information System (INIS)

    Park, Yun Bum; Lee, Jae Seon; Kim, Jong Wook; Han, Eun Sil; Park, Hee June

    2016-01-01

    A CRDM (Control Rod Drive Mechanism) is an electromagnetic device which drives a control rod assembly linearly to regulate the reactivity of a nuclear core. A RPIS (Rod Position Indication System) is used as a position indicator of a control rod assembly for a CRDM of a nuclear reactor, SMART. A highly accurate RPIS for SMART is required because the reactivity of a nuclear core for a small modular reactor is more sensitive than the commercial ones. In this study, the effect of positioning direction of the reeds in a reed switch for the CRDM RPIS has been studied using the electromagnetic FE analysis. It is found that the positioning direction of the reeds slightly but not significantly affects the formation of attraction. Analysis results will be used as the basis on estimated accuracy of full RPIS system.

  15. Rotation Impact of Reed Switch

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yun Bum; Lee, Jae Seon; Kim, Jong Wook [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Han, Eun Sil [Taesung S and E, Seoul (Korea, Republic of); Park, Hee June [Woojin Inc., Hwaseong (Korea, Republic of)

    2016-10-15

    A CRDM (Control Rod Drive Mechanism) is an electromagnetic device which drives a control rod assembly linearly to regulate the reactivity of a nuclear core. A RPIS (Rod Position Indication System) is used as a position indicator of a control rod assembly for a CRDM of a nuclear reactor, SMART. A highly accurate RPIS for SMART is required because the reactivity of a nuclear core for a small modular reactor is more sensitive than the commercial ones. In this study, the effect of positioning direction of the reeds in a reed switch for the CRDM RPIS has been studied using the electromagnetic FE analysis. It is found that the positioning direction of the reeds slightly but not significantly affects the formation of attraction. Analysis results will be used as the basis on estimated accuracy of full RPIS system.

  16. Chiroptical Molecular Switches 1; Principles and Syntheses.

    NARCIS (Netherlands)

    Lange, Ben de; Jager, Wolter F.; Feringa, Bernard

    1992-01-01

    The concept and the synthesis of the basic molecules for a chiroptical molecular switch are described. This molecular switch is based on photochemical interconversion of two bistable forms of chiral sterically overcrowded olefins. A large variety of these alkenes with different properties have been

  17. Novel RF-MEMS capacitive switching structures

    NARCIS (Netherlands)

    Rottenberg, X.; Jansen, Henricus V.; Fiorini, P.; De Raedt, W.; Tilmans, H.A.C.

    2002-01-01

    This paper reports on novel RF-MEMS capacitive switching devices implementing an electrically floating metal layer covering the dielectric to ensure intimate contact with the bridge in the down state. This results in an optimal switch down capacitance and allows optimisation of the down/up

  18. High-explosive driven crowbar switch

    International Nuclear Information System (INIS)

    Dike, R.S.; Kewish, R.W. Jr.

    1976-01-01

    The disclosure relates to a compact explosive driven switch for use as a low resistance, low inductance crowbar switch. A high-explosive charge extrudes a deformable conductive metallic plate through a polyethylene insulating layer to achieve a hard current contact with a supportive annular conductor

  19. Simulation of linear Switched Reluctance Motor drives

    OpenAIRE

    Garcia Amoros, Jordi; Blanqué Molina, Balduino; Andrada Gascón, Pedro

    2011-01-01

    This paper presents a simulation model of linear switched reluctance motor drives. A Matlab-Simulink environment coupled with finite element analysis is used to perform the simulations. Experimental and simulation results for a double sided linear switched motor drive prototype are reported and compared to verify the simulation model.

  20. Internal Backpressure for Terabit Switch Fabrics

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Ruepp, Sarah Renée; Rytlig, Andreas

    2012-01-01

    This paper proposes and analyzes the efficiency of novel backpressure schemes for Terabit switch fabrics. The proposed schemes aim at buffer optimization under uniform traffic distribution with Bernoulli packet arrival process. Results show that a reduction of the needed maximum buffer capacity w...... with up to 47% can be achieved with switch-internal backpressure mechanisms at the expense of a small control overhead....

  1. Microelectromechanical Switches for Phased Array Antennas

    Science.gov (United States)

    Ponchak, George E.; Simons, Rainee N.; Scardelletti, Maximillian; Varaljay, Nicholas C.

    2000-01-01

    Preliminary results are presented on the fabrication and testing of a MicroElectro-Mechanical (MEM) microstrip series switch. This switch is being developed for use in a K-band phased array antenna that NASA will use for communication links in its Earth orbiting satellites. Preliminary insertion loss and isolation measurements are presented.

  2. Photonic crystal Fano lasers and Fano switches

    DEFF Research Database (Denmark)

    Mørk, Jesper; Yu, Yi; Bekele, Dagmawi Alemayehu

    2017-01-01

    We show that Fano resonances can be realized in photonic crystal membrane structures by coupling line-defect waveguides and point-defect nanocavities. The Fano resonance can be exploited to realize optical switches with very small switching energy, as well as Fano lasers, that can generate short...

  3. Scalable optical switches for computing applications

    NARCIS (Netherlands)

    White, I.H.; Aw, E.T.; Williams, K.A.; Wang, Haibo; Wonfor, A.; Penty, R.V.

    2009-01-01

    A scalable photonic interconnection network architecture is proposed whereby a Clos network is populated with broadcast-and-select stages. This enables the efficient exploitation of an emerging class of photonic integrated switch fabric. A low distortion space switch technology based on recently

  4. Tutorial: Integrated-photonic switching structures

    Science.gov (United States)

    Soref, Richard

    2018-02-01

    Recent developments in waveguided 2 × 2 and N × M photonic switches are reviewed, including both broadband and narrowband resonant devices for the Si, InP, and AlN platforms. Practical actuation of switches by electro-optical and thermo-optical techniques is discussed. Present datacom-and-computing applications are reviewed, and potential applications are proposed for chip-scale photonic and optoelectronic integrated switching networks. Potential is found in the reconfigurable, programmable "mesh" switches that enable a promising group of applications in new areas beyond those in data centers and cloud servers. Many important matrix switches use gated semiconductor optical amplifiers. The family of broadband, directional-coupler 2 × 2 switches featuring two or three side-coupled waveguides deserves future experimentation, including devices that employ phase-change materials. The newer 2 × 2 resonant switches include standing-wave resonators, different from the micro-ring traveling-wave resonators. The resonant devices comprise nanobeam interferometers, complex-Bragg interferometers, and asymmetric contra-directional couplers. Although the fast, resonant devices offer ultralow switching energy, ˜1 fJ/bit, they have limitations. They require several trade-offs when deployed, but they do have practical application.

  5. Proceedings of the switched power workshop

    International Nuclear Information System (INIS)

    Fernow, R.C.

    1988-01-01

    These proceedings contain most of the presentations given at a workshop on the current state of research in techniques for switched power acceleration. The proceedings are divided, as was the workshop itself, into two parts. Part 1, contains the latest results from a number of groups active in switched power research. The major topic here is a method for switching externally supplied power onto a transmission line. Advocates for vacuum photodiode switching, solid state switching, gas switching, and synthetic pulse generation are all presented. Other important areas of research described in this section concern: external electrical and laser pulsing systems; the properties of the created electromagnetic pulse; structures used for transporting the electromagnetic pulse to the region where the electron beam is located; and possible applications. Part 2 of the proceedings considers the problem of designing a high brightness electron gun using switched power as the power source. This is an important first step in demonstrating the usefulness of switched power techniques for accelerator physics. In addition such a gun could have immediate practical importance for advanced acceleration studies since the brightness could exceed that of present sources by several orders of magnitude. I would like to take this opportunity to thank Kathleen Tuohy and Patricia Tuttle for their assistance in organizing and running the workshop. Their tireless efforts contribute greatly to a very productive meeting

  6. Unity power factor switching regulator

    Science.gov (United States)

    Rippel, Wally E. (Inventor)

    1983-01-01

    A single or multiphase boost chopper regulator operating with unity power factor, for use such as to charge a battery is comprised of a power section for converting single or multiphase line energy into recharge energy including a rectifier (10), one inductor (L.sub.1) and one chopper (Q.sub.1) for each chopper phase for presenting a load (battery) with a current output, and duty cycle control means (16) for each chopper to control the average inductor current over each period of the chopper, and a sensing and control section including means (20) for sensing at least one load parameter, means (22) for producing a current command signal as a function of said parameter, means (26) for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of the chopper, means (28) for sensing current through said inductor, means (18) for comparing said feedback signal with said sensed current to produce, in response to a difference, a control signal applied to the duty cycle control means, whereby the average inductor current is proportionate to the average rectifier voltage output over each period of the chopper, and instantaneous line current is thereby maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor. The boost chopper is comprised of a plurality of converters connected in parallel and operated in staggered phase. For optimal harmonic suppression, the duty cycles of the switching converters are evenly spaced, and by negative coupling between pairs 180.degree. out-of-phase, peak currents through the switches can be reduced while reducing the inductor size and mass.

  7. Switched-capacitor isolated LED driver

    Science.gov (United States)

    Sanders, Seth R.; Kline, Mitchell

    2016-03-22

    A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V.sub.DC. A regulator section, operating on V.sub.DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

  8. Seismic switch for strong motion measurement

    Science.gov (United States)

    Harben, P.E.; Rodgers, P.W.; Ewert, D.W.

    1995-05-30

    A seismic switching device is described that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period. 11 figs.

  9. Intentional preparation of auditory attention-switches: Explicit cueing and sequential switch-predictability.

    Science.gov (United States)

    Seibold, Julia C; Nolden, Sophie; Oberem, Josefa; Fels, Janina; Koch, Iring

    2018-06-01

    In an auditory attention-switching paradigm, participants heard two simultaneously spoken number-words, each presented to one ear, and decided whether the target number was smaller or larger than 5 by pressing a left or right key. An instructional cue in each trial indicated which feature had to be used to identify the target number (e.g., female voice). Auditory attention-switch costs were found when this feature changed compared to when it repeated in two consecutive trials. Earlier studies employing this paradigm showed mixed results when they examined whether such cued auditory attention-switches can be prepared actively during the cue-stimulus interval. This study systematically assessed which preconditions are necessary for the advance preparation of auditory attention-switches. Three experiments were conducted that controlled for cue-repetition benefits, modality switches between cue and stimuli, as well as for predictability of the switch-sequence. Only in the third experiment, in which predictability for an attention-switch was maximal due to a pre-instructed switch-sequence and predictable stimulus onsets, active switch-specific preparation was found. These results suggest that the cognitive system can prepare auditory attention-switches, and this preparation seems to be triggered primarily by the memorised switching-sequence and valid expectations about the time of target onset.

  10. Contraceptive method switching in the United States.

    Science.gov (United States)

    Grady, William R; Billy, John O G; Klepinger, Daniel H

    2002-01-01

    Switching among contraceptive method types is the primary determinant of the prevalence of use of specific contraceptive methods, and it has direct implications for women's ability to avoid unintended pregnancies. Yet, method switching among U.S. women has received little attention from researchers. Data from the 1995 National Survey of Family Growth were used to construct multiple-decrement life tables to explore the gross switching rates of married and unmarried women. Within each group, discrete-time hazard models were estimated to determine how women's characteristics affect their switching behavior. Overall rates of method switching are high among both married and unmarried women (40% and 61%, respectively). Married women's two-year switching rates vary from 30% among women who use the implant, injectable, IUD or other reversible methods to 43% among nonusers, while unmarried women's rates vary from 33% among women who use the implant, injectable or IUD to 70% among nonusers. Multivariate analyses of method switching according to women's characteristics indicate that among married women, women without children are less likely than other women to adopt sterilization or a long-term reversible contraceptive (the implant, injectable or IUD). Older married women have a higher rate than their younger counterparts of switching to sterilization, but are also more likely to continue using no method. Among unmarried women, younger and more highly educated women have high rates of switching to the condom and to dual methods. Women's method switching decisions may be driven primarily by concerns related to level and duration of contraceptive effectiveness, health risks associated with contraceptive use and, among single women, sexually transmitted disease prevention.

  11. Development of the switching components for ZT-40

    International Nuclear Information System (INIS)

    Melton, J.G.; Dike, R.S.; Hanks, K.W.; Nunnally, W.C.

    1977-01-01

    Switching of the main capacitor banks for ZT-40 will be accomplished by spark gap switches. Initially, there will be 576 start switches and 288 crowbar switches. A development program is under way to develop three switches; (1) a versatile start switch, which can be used for both the I/sub z/ and the I/sub theta/ capacitor banks, with a wide operating voltage range, (2) a crowbar switch which is capable of crowbarring the circuit without the power crowbar bank, and (3) a power crowbar switch, which can handle 50 to 100 coulombs, so that a large number of crowbar switches will not be required when the power crowbar circuit is added. The problems with the start switches and the first crowbar switch have been solved, or alleviated. The development of a power crowbar switch has just begun

  12. Call for Papers: Photonics in Switching

    Science.gov (United States)

    Wosinska, Lena; Glick, Madeleine

    2006-04-01

    Call for Papers: Photonics in Switching Guest Editors: Lena Wosinska, Royal Institute of Technology (KTH) / ICT Sweden Madeleine Glick, Intel Research, Cambridge, UK Technologies based on DWDM systems allow data transmission with bit rates of Tbit/s on a single fiber. To facilitate this enormous transmission volume, high-capacity and high-speed network nodes become inevitable in the optical network. Wideband switching, WDM switching, optical burst switching (OBS), and optical packet switching (OPS) are promising technologies for harnessing the bandwidth of WDM optical fiber networks in a highly flexible and efficient manner. As a number of key optical component technologies approach maturity, photonics in switching is becoming an increasingly attractive and practical solution for the next-generation of optical networks. The scope of this special issue is focused on the technology and architecture of optical switching nodes, including the architectural and algorithmic aspects of high-speed optical networks. Scope of Submission The scope of the papers includes, but is not limited to, the following topics: WDM node architectures Novel device technologies enabling photonics in switching, such as optical switch fabrics, optical memory, and wavelength conversion Routing protocols WDM switching and routing Quality of service Performance measurement and evaluation Next-generation optical networks: architecture, signaling, and control Traffic measurement and field trials Optical burst and packet switching OBS/OPS node architectures Burst/Packet scheduling and routing algorithms Contention resolution/avoidance strategies Services and applications for OBS/OPS (e.g., grid networks, storage-area networks, etc.) Burst assembly and ingress traffic shaping Hybrid OBS/TDM or OBS/wavelength routing Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON and select ``Photonics in Switching' in the features indicator of the online

  13. Resistance switching memory in perovskite oxides

    International Nuclear Information System (INIS)

    Yan, Z.B.; Liu, J.-M.

    2015-01-01

    The resistance switching behavior has recently attracted great attentions for its application as resistive random access memories (RRAMs) due to a variety of advantages such as simple structure, high-density, high-speed and low-power. As a leading storage media, the transition metal perovskite oxide owns the strong correlation of electrons and the stable crystal structure, which brings out multifunctionality such as ferroelectric, multiferroic, superconductor, and colossal magnetoresistance/electroresistance effect, etc. The existence of rich electronic phases, metal–insulator transition and the nonstoichiometric oxygen in perovskite oxide provides good platforms to insight into the resistive switching mechanisms. In this review, we first introduce the general characteristics of the resistance switching effects, the operation methods and the storage media. Then, the experimental evidences of conductive filaments, the transport and switching mechanisms, and the memory performances and enhancing methods of perovskite oxide based filamentary RRAM cells have been summarized and discussed. Subsequently, the switching mechanisms and the performances of the uniform RRAM cells associating with the carrier trapping/detrapping and the ferroelectric polarization switching have been discussed. Finally, the advices and outlook for further investigating the resistance switching and enhancing the memory performances are given

  14. Reluctance motor employing superconducting magnetic flux switches

    International Nuclear Information System (INIS)

    Spyker, R.L.; Ruckstadter, E.J.

    1992-01-01

    This paper reports that superconducting flux switches controlling the magnetic flux in the poles of a motor will enable the implementation of a reluctance motor using one central single phase winding. A superconducting flux switch consists of a ring of superconducting material surrounding a ferromagnetic pole of the motor. When in the superconducting state the switch will block all magnetic flux attempting to flow in the ferromagnetic core. When switched to the normal state the superconducting switch will allow the magnetic flux to flow freely in that pole. By using one high turns-count coil as a flux generator, and selectively channeling flux among the various poles using the superconducting flux switch, 3-phase operation can be emulated with a single-hase central AC source. The motor will also operate when the flux generating coil is driven by a DC current, provided the magnetic flux switches see a continuously varying magnetic flux. Rotor rotation provides this varying flux due to the change in stator pole inductance it produces

  15. Subnanosecond photoconductive switching in GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R.L.; Pocha, M.D.; Griffin, K.L.

    1991-04-01

    We are conducting research in photoconductive switching for the purpose of generating microwave pulses with amplitudes up to 50 kV. This technology has direct application to impulse radar and HPM sources. We are exploiting the very fast recombination rates of Gallium Arsenide (GaAs) to explore the potential of GaAs as an on-off switch when operating in the linear mode (the linear mode is defined such that one carrier pair is generated for each photon absorbed). In addition, we are exploring the potential GaAs to act as a closing switch in ``avalanche`` mode at high fields. We have observed switch closing times of less than 200 psec with a 100 psec duration laser pulse and opening times of less than 400 psec with neutron irradiated GaAs at fields of tens of kV/cm. If the field is increased and the laser energy decreased, the laser can be used to trigger photoconductive switches into ``avalanche`` mode of operation in which carrier multiplication occurs. This mode of operation is quite promising since the switches close in less than 1 nsec while realizing significant energy gain (ratio of electrical energy in the pulse to optical trigger energy). We are currently investigating both large area (1 sq cm) and small area (< 1 sq mm) switches illuminated by GaAlAs laser diodes at 900 nm and Nd:YAG lasers at 1.06 micrometers. Preliminary results indicate that the closing time of the avalanche switches depends primarily on the material properties of the devices with closing times of 300--1300 psec at voltages of 6--35 kV. We will present experimental results for linear, lock on and avalanche mode operation of GaAs photoconductive switches and how these pulses may be applied to microwave generation. 3 refs.

  16. Subnanosecond photoconductive switching in GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R.L.; Pocha, M.D.; Griffin, K.L.

    1991-04-01

    We are conducting research in photoconductive switching for the purpose of generating microwave pulses with amplitudes up to 50 kV. This technology has direct application to impulse radar and HPM sources. We are exploiting the very fast recombination rates of Gallium Arsenide (GaAs) to explore the potential of GaAs as an on-off switch when operating in the linear mode (the linear mode is defined such that one carrier pair is generated for each photon absorbed). In addition, we are exploring the potential GaAs to act as a closing switch in avalanche'' mode at high fields. We have observed switch closing times of less than 200 psec with a 100 psec duration laser pulse and opening times of less than 400 psec with neutron irradiated GaAs at fields of tens of kV/cm. If the field is increased and the laser energy decreased, the laser can be used to trigger photoconductive switches into avalanche'' mode of operation in which carrier multiplication occurs. This mode of operation is quite promising since the switches close in less than 1 nsec while realizing significant energy gain (ratio of electrical energy in the pulse to optical trigger energy). We are currently investigating both large area (1 sq cm) and small area (< 1 sq mm) switches illuminated by GaAlAs laser diodes at 900 nm and Nd:YAG lasers at 1.06 micrometers. Preliminary results indicate that the closing time of the avalanche switches depends primarily on the material properties of the devices with closing times of 300--1300 psec at voltages of 6--35 kV. We will present experimental results for linear, lock on and avalanche mode operation of GaAs photoconductive switches and how these pulses may be applied to microwave generation. 3 refs.

  17. Subnanosecond photoconductive switching in GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Druce, R.L.; Pocha, M.D.; Griffin, K.L.

    1990-01-01

    We are conducting research in photoconductive switching for the purpose of generating microwave pulses with amplitudes up to 50 kV. This technology has direct application to impulse radar and HPM sources. We are exploiting the very fast recombination rates of Gallium Arsenide (GaAs) to explore the potential of GaAs as an on-off switch when operating in the linear mode (the linear mode is defined such that one carrier pair is generated for each photon absorbed). In addition, we are exploring the potential of GaAs to act as a closing switch in avalanche'' mode at high fields. We have observed switch closing times of less than 200 psec with 100 psec duration laser pulse and opening times of less than 400 psec with neutron irradiated GaAs at fields of tens of kV/cm. If the field is increased and the laser energy decreased, the laser can be used to trigger photoconductive switches into an avalanche'' mode of operation in which carrier multiplication occurs. This mode of operation is quite promising since the switches close in less than 1 nsec while realizing significant energy gain (ratio of electrical energy in the pulse to optical trigger energy). We are currently investigating both large are (1 sq cm) and small area (<1 sq mm) switches illuminated by GaAlAs laser diodes at 900 nm and Nd:YAG lasers at 1.06 micrometers. Preliminary results indicate that the closing time of the avalanche switches depends primarily on the material properties of the devices with closing times of 300--1300 psec at voltages of 6-35 kV. We will present experimental results for linear, lock on and avalanche mode operation of GaAs photoconductive switches and how these pulses may be applied to microwave generation. 3 refs., 11 figs.

  18. Subnanosecond photoconductive switching in GaAs

    Science.gov (United States)

    Druce, R. L.; Pocha, M. D.; Griffin, K. L.

    1991-04-01

    We are conducting research in photoconductive switching for the purpose of generating microwave pulses with amplitudes up to 50 kV. This technology has direct application to impulse radar and HPM sources. We are exploiting the very fast recombination rates of Gallium Arsenide (GaAs) to explore the potential of GaAs as an on-off switch when operating in the linear mode (the linear mode is defined such that one carrier pair is generated for each photon absorbed). In addition, we are exploring the potential GaAs to act as a closing switch in 'avalanche' mode at high fields. We have observed switch closing times of less than 200 psec with a 100 psec duration laser pulse and opening times of less than 400 psec with neutron irradiated GaAs at fields of tens of kV/cm. If the field is increased and the laser energy decreased, the laser can be used to trigger photoconductive switches into 'avalanche' mode of operation in which carrier multiplication occurs. This mode of operation is quite promising since the switches close in less than 1 nsec while realizing significant energy gain (ratio of electrical energy in the pulse to optical trigger energy). We are currently investigating both large area (1 sq cm) and small area (less than 1 sq mm) switches illuminated by GaAlAs laser diodes at 900 nm and Nd:YAG lasers at 1.06 micrometers. Preliminary results indicate that the closing time of the avalanche switches depends primarily on the material properties of the devices with closing times of 300-1300 psec at voltages of 6-35 kV. We will present experimental results for linear, lock on, and avalanche mode operation of GaAs photoconductive switches and how these pulses may be applied to microwave generation.

  19. Organization of the channel-switching process in parallel computer systems based on a matrix optical switch

    Science.gov (United States)

    Golomidov, Y. V.; Li, S. K.; Popov, S. A.; Smolov, V. B.

    1986-01-01

    After a classification and analysis of electronic and optoelectronic switching devices, the design principles and structure of a matrix optical switch is described. The switching and pair-exclusion operations in this type of switch are examined, and a method for the optical switching of communication channels is elaborated. Finally, attention is given to the structural organization of a parallel computer system with a matrix optical switch.

  20. DESAIN DAN IMPLEMENTSI SOFT SWITCHING BOOST KONVERTER DENGAN SIMPLE AUXILLARY RESONANT SWITCH (SARC

    Directory of Open Access Journals (Sweden)

    Dimas Bagus Saputra

    2017-01-01

    Full Text Available Boost konverter merupakan penaik tegangan DC ke tegangan DC yang mempunyai tegangan output yang lebih tinggi dibanding inputnya. Penggunaan boost konverter diera modern semakin meningkat dan dibuat dengan dimensi yang lebih kecil, berat yang lebih ringan dan efisiensi yang lebih tinggi dibanding dengan boost konverter generasi terdahulu. Tetapi rugi-rugi periodik saat on/off meningkat. Untuk meraih kriteria tersebut, teknik hard switching boost konverter berevolusi menjadi teknik soft switching dengan menambah rangkaian simple auxiliary resonant circuit (SARC. Karena penambahan rangkaian SARC tersebut konverter bekerja pada kondisi zero-voltage switching switch (ZVS dan zero current switch (ZCS, sehingga saklar semikonduktor tidak bekerja secara hard switching lagi. Pada penelitian ini akan di desain dan diimplementaskan soft switching boost konverter dengan SARC. Kelebihan dari soft switching boost konverter dengan SARC adalah mempunyai efisiensi yang lebih tinggi dibanding dengan boost konverter konventional. Dari hasil implementasi menunjukkan konverter yang diajukan telah meraih zero voltage switch (ZVS. Sehingga boost konverter zero voltage switch (ZVS bisa diaplikasikan pada sistem power suplay yang membutuhkan efisiensi energi yang tinggi terutama pada daya yang tinggi.

  1. Comparison of switching control algorithms effective in restricting the switching in the neighborhood of the origin

    International Nuclear Information System (INIS)

    Joung, JinWook; Chung, Lan; Smyth, Andrew W

    2010-01-01

    The active interaction control (AIC) system consisting of a primary structure, an auxiliary structure and an interaction element was proposed to protect the primary structure against earthquakes and winds. The objective of the AIC system in reducing the responses of the primary structure is fulfilled by activating or deactivating the switching between the engagement and the disengagement of the primary and auxiliary structures through the interaction element. The status of the interaction element is controlled by switching control algorithms. The previously developed switching control algorithms require an excessive amount of switching, which is inefficient. In this paper, the excessive amount of switching is restricted by imposing an appropriately designed switching boundary region, where switching is prohibited, on pre-designed engagement–disengagement conditions. Two different approaches are used in designing the newly proposed AID-off and AID-off 2 algorithms. The AID-off 2 algorithm is designed to affect deactivated switching regions explicitly, unlike the AID-off algorithm, which follows the same procedure of designing the engagement–disengagement conditions of the previously developed algorithms, by using the current status of the AIC system. Both algorithms are shown to be effective in reducing the amount of switching times triggered from the previously developed AID algorithm under an appropriately selected control sampling period for different earthquakes, but the AID-off 2 algorithm outperforms the AID-off algorithm in reducing the number of switching times

  2. Exponential Stability of Switched Positive Homogeneous Systems

    Directory of Open Access Journals (Sweden)

    Dadong Tian

    2017-01-01

    Full Text Available This paper studies the exponential stability of switched positive nonlinear systems defined by cooperative and homogeneous vector fields. In order to capture the decay rate of such systems, we first consider the subsystems. A sufficient condition for exponential stability of subsystems with time-varying delays is derived. In particular, for the corresponding delay-free systems, we prove that this sufficient condition is also necessary. Then, we present a sufficient condition of exponential stability under minimum dwell time switching for the switched positive nonlinear systems. Some results in the previous literature are extended. Finally, a numerical example is given to demonstrate the effectiveness of the obtained results.

  3. High voltage superconducting switch for power application

    International Nuclear Information System (INIS)

    Mawardi, O.; Ferendeci, A.; Gattozzi, A.

    1983-01-01

    This paper reports the development of a novel interrupter which meets the requirements of a high voltage direct current (HVDC) power switch and at the same time doubles as a current limiter. The basic concept of the interrupter makes use of a fast superconducting, high capacity (SHIC) switch that carries the full load current while in the superconducting state and reverts to the normal resistive state when triggered. Typical design parameters are examined for the case of a HVDC transmission line handling 2.5KA at 150KVDC. The result is a power switch with superior performance and smaller size than the ones reported to date

  4. Consumer poaching, brand switching, and price transparency

    DEFF Research Database (Denmark)

    Schultz, Christian

    2014-01-01

    This paper addresses price transparency on the consumer side in markets with behavioral price discrimination which feature welfare reducing brand switching. When long-term contracts are not available, an increase in transparency intensifies competition, lowers prices and profits, reduces brand...... switching and benefits consumers and welfare. With long-term contracts, an increase in transparency reduces the use of long-term contracts, leading to more brand switching and a welfare loss. Otherwise, the results are the same as without long-term contracts....

  5. Electrically switched cesium ion exchange

    International Nuclear Information System (INIS)

    Lilga, M.A.; Orth, R.J.; Sukamto, J.P.H.; Schwartz, D.T.; Haight, S.M.; Genders, J.D.

    1997-04-01

    Electrically Switched Ion Exchange (ESIX) is a separation technology being developed as an alternative to conventional ion exchange for removing radionuclides from high-level waste. The ESIX technology, which combines ion exchange and electrochemistry, is geared toward producing electroactive films that are highly selective, regenerable, and long lasting. During the process, ion uptake and elution are controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto a high surface area electrode. This method adds little sodium to the waste stream and minimizes the secondary wastes associated with traditional ion exchange techniques. Development of the ESIX process is well underway for cesium removal using ferrocyanides as the electroactive films. Films having selectivity for perrhenate (a pertechnetate surrogate) over nitrate also have been deposited and tested. A case study for the KE Basin on the Hanford Site was conducted based on the results of the development testing. Engineering design baseline parameters for film deposition, film regeneration, cesium loading, and cesium elution were used for developing a conceptual system. Order of magnitude cost estimates were developed to compare with conventional ion exchange. This case study demonstrated that KE Basin wastewater could be processed continuously with minimal secondary waste and reduced associated disposal costs, as well as lower capital and labor expenditures

  6. Controllability of multi-agent systems with periodically switching topologies and switching leaders

    Science.gov (United States)

    Tian, Lingling; Zhao, Bin; Wang, Long

    2018-05-01

    This paper considers controllability of multi-agent systems with periodically switching topologies and switching leaders. The concept of m-periodic controllability is proposed, and a criterion for m-periodic controllability is established. The effect of the duration of subsystems on controllability is analysed by utilising a property of analytic functions. In addition, the influence of switching periods on controllability is investigated, and an algorithm is proposed to search for the fewest periods to ensure controllability. A necessary condition for m-periodic controllability is obtained from the perspective of eigenvectors of the subsystems' Laplacian matrices. For a system with switching leaders, it is proved that switching-leader controllability is equivalent to multiple-leader controllability. Furthermore, both the switching order and the tenure of agents being leaders have no effect on the controllability. Some examples are provided to illustrate the theoretical results.

  7. Instability in time-delayed switched systems induced by fast and random switching

    Science.gov (United States)

    Guo, Yao; Lin, Wei; Chen, Yuming; Wu, Jianhong

    2017-07-01

    In this paper, we consider a switched system comprising finitely or infinitely many subsystems described by linear time-delayed differential equations and a rule that orchestrates the system switching randomly among these subsystems, where the switching times are also randomly chosen. We first construct a counterintuitive example where even though all the time-delayed subsystems are exponentially stable, the behaviors of the randomly switched system change from stable dynamics to unstable dynamics with a decrease of the dwell time. Then by using the theories of stochastic processes and delay differential equations, we present a general result on when this fast and random switching induced instability should occur and we extend this to the case of nonlinear time-delayed switched systems as well.

  8. Analysis of Switched-Rigid Floating Oscillator

    Directory of Open Access Journals (Sweden)

    Prabhakar R. Marur

    2009-01-01

    Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.

  9. Multi-planed unified switching topologies

    Science.gov (United States)

    Chen, Dong; Heidelberger, Philip; Sugawara, Yutaka

    2017-07-04

    An apparatus and method for extending the scalability and improving the partitionability of networks that contain all-to-all links for transporting packet traffic from a source endpoint to a destination endpoint with low per-endpoint (per-server) cost and a small number of hops. An all-to-all wiring in the baseline topology is decomposed into smaller all-to-all components in which each smaller all-to-all connection is replaced with star topology by using global switches. Stacking multiple copies of the star topology baseline network creates a multi-planed switching topology for transporting packet traffic. Point-to-point unified stacking method using global switch wiring methods connects multiple planes of a baseline topology by using the global switches to create a large network size with a low number of hops, i.e., low network latency. Grouped unified stacking method increases the scalability (network size) of a stacked topology.

  10. Nano- and micro-electromechanical switch dynamics

    International Nuclear Information System (INIS)

    Pulskamp, Jeffrey S; Proie, Robert M; Polcawich, Ronald G

    2013-01-01

    This paper reports theoretical analysis and experimental results on the dynamics of piezoelectric MEMS mechanical logic relays. The multiple degree of freedom analytical model, based on modal decomposition, utilizes modal parameters obtained from finite element analysis and an analytical model of piezoelectric actuation. The model accounts for exact device geometry, damping, drive waveform variables, and high electric field piezoelectric nonlinearity. The piezoelectrically excited modal force is calculated directly and provides insight into design optimization for switching speed. The model accurately predicts the propagation delay dependence on actuation voltage of mechanically distinct relay designs. The model explains the observed discrepancies in switching speed of these devices relative to single degree of freedom switching speed models and suggests the strong potential for improved switching speed performance in relays designed for mechanical logic and RF circuits through the exploitation of higher order vibrational modes. (paper)

  11. Proton-Controlled Organic Microlaser Switch.

    Science.gov (United States)

    Gao, Zhenhua; Zhang, Wei; Yan, Yongli; Yi, Jun; Dong, Haiyun; Wang, Kang; Yao, Jiannian; Zhao, Yong Sheng

    2018-05-25

    Microscale laser switches have been playing irreplaceable roles in the development of photonic devices with high integration levels. However, it remains a challenge to switch the lasing wavelengths across a wide range due to relatively fixed energy bands in traditional semiconductors. Here, we report a strategy to switch the lasing wavelengths among multiple states based on a proton-controlled intramolecular charge-transfer (ICT) process in organic dye-doped flexible microsphere resonant cavities. The protonic acids can effectively bind onto the ICT molecules, which thus enhance the ICT strength of the dyes and lead to a red-shifted gain behavior. On this basis, the gain region was effectively modulated by using acids with different proton-donating ability, and as a result, laser switching among multiple wavelengths was achieved. The results will provide guidance for the rational design of miniaturized lasers with performances based on the characteristic of organic optoelectronic materials.

  12. Delayed switching applied to memristor neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Frank Z.; Yang Xiao; Lim Guan [Future Computing Group, School of Computing, University of Kent, Canterbury (United Kingdom); Helian Na [School of Computer Science, University of Hertfordshire, Hatfield (United Kingdom); Wu Sining [Xyratex, Havant (United Kingdom); Guo Yike [Department of Computing, Imperial College, London (United Kingdom); Rashid, Md Mamunur [CERN, Geneva (Switzerland)

    2012-04-01

    Magnetic flux and electric charge are linked in a memristor. We reported recently that a memristor has a peculiar effect in which the switching takes place with a time delay because a memristor possesses a certain inertia. This effect was named the ''delayed switching effect.'' In this work, we elaborate on the importance of delayed switching in a brain-like computer using memristor neural networks. The effect is used to control the switching of a memristor synapse between two neurons that fire together (the Hebbian rule). A theoretical formula is found, and the design is verified by a simulation. We have also built an experimental setup consisting of electronic memristive synapses and electronic neurons.

  13. Delayed switching applied to memristor neural networks

    International Nuclear Information System (INIS)

    Wang, Frank Z.; Yang Xiao; Lim Guan; Helian Na; Wu Sining; Guo Yike; Rashid, Md Mamunur

    2012-01-01

    Magnetic flux and electric charge are linked in a memristor. We reported recently that a memristor has a peculiar effect in which the switching takes place with a time delay because a memristor possesses a certain inertia. This effect was named the ''delayed switching effect.'' In this work, we elaborate on the importance of delayed switching in a brain-like computer using memristor neural networks. The effect is used to control the switching of a memristor synapse between two neurons that fire together (the Hebbian rule). A theoretical formula is found, and the design is verified by a simulation. We have also built an experimental setup consisting of electronic memristive synapses and electronic neurons.

  14. A nanoplasmonic switch based on molecular machines

    KAUST Repository

    Zheng, Yue Bing; Yang, Ying-Wei; Jensen, Lasse; Fang, Lei; Juluri, Bala Krishna; Weiss, Paul S.; Stoddart, J. Fraser; Huang, Tony Jun

    2009-01-01

    We aim to develop a molecular-machine-driven nanoplasmonic switch for its use in future nanophotonic integrated circuits (ICs) that have applications in optical communication, information processing, biological and chemical sensing. Experimental

  15. Topological photonic orbital-angular-momentum switch

    Science.gov (United States)

    Luo, Xi-Wang; Zhang, Chuanwei; Guo, Guang-Can; Zhou, Zheng-Wei

    2018-04-01

    The large number of available orbital-angular-momentum (OAM) states of photons provides a unique resource for many important applications in quantum information and optical communications. However, conventional OAM switching devices usually rely on precise parameter control and are limited by slow switching rate and low efficiency. Here we propose a robust, fast, and efficient photonic OAM switch device based on a topological process, where photons are adiabatically pumped to a target OAM state on demand. Such topological OAM pumping can be realized through manipulating photons in a few degenerate main cavities and involves only a limited number of optical elements. A large change of OAM at ˜10q can be realized with only q degenerate main cavities and at most 5 q pumping cycles. The topological photonic OAM switch may become a powerful device for broad applications in many different fields and motivate a topological design of conventional optical devices.

  16. Switching overvoltages in offshore wind power grids

    DEFF Research Database (Denmark)

    Arana Aristi, Ivan

    and cables are presented. In Chapter 4 results from time domain measurements and simulations of switching operations in offshore wind power grids are described. Specifically, switching operations on a single wind turbine, the collection grid, the export system and the external grid measured in several real...... offshore wind farms are shown together with simulation results. Switching operations in offshore wind power grids can be simulated with different electromagnetic transient programs. Different programs were used in the project and compared results are included in Chapter 4. Also in Chapter 4 different......Switching transients in wind turbines, the collection grid, the export system and the external grid in offshore wind farms, during normal or abnormal operation, are the most important phenomena when conducting insulation coordination studies. However, the recommended models and methods from...

  17. Bistable fluidic valve is electrically switched

    Science.gov (United States)

    Fiet, O.; Salvinski, R. J.

    1970-01-01

    Bistable control valve is selectively switched by direct application of an electrical field to divert fluid from one output channel to another. Valve is inexpensive, has no moving parts, and operates on fluids which are relatively poor electrical conductors.

  18. Modeling switching behaviour of direct selling customers

    Directory of Open Access Journals (Sweden)

    P Msweli-Mbanga

    2004-04-01

    Full Text Available The direct selling industry suffers a high turnover rate of salespeople, resulting in high costs of training new salespeople. Further costs are incurred when broken relationships with customers cause them to switch from one product supplier to another. This study identifies twelve factors that drive the switching behaviour of direct sales customers and examines the extent to which these factors influence switching. Exploratory factor analysis was used to assess the validity of these factors. The factors were represented in a model that posits that an interpersonal relationship between a direct sales person and a customer moderates the relationship between switching behaviour and loyalty. Structural equation modeling was used to test the proposed model. The author then discusses the empirical findings and their managerial implications, providing further avenues for research.

  19. Active plasmonics in WDM traffic switching applications

    DEFF Research Database (Denmark)

    Papaioannou, S.; Kalavrouziotis, D.; Vyrsokinos, K.

    2012-01-01

    -enabling characteristics of active plasmonic circuits with an ultra-low power 3 response time product represents a crucial milestone in the development of active plasmonics towards real telecom and datacom applications, where low-energy and fast TO operation with small-size circuitry is targeted........ The first active Dielectric-Loaded Surface Plasmon Polariton (DLSPP) thermo-optic (TO) switches with successful performance in single-channel 10 Gb/s data traffic environments have led the inroad towards bringing low-power active plasmonics in practical traffic applications. In this article, we introduce...... active plasmonics into Wavelength Division Multiplexed (WDM) switching applications, using the smallest TO DLSPP-based Mach-Zehnder interferometric switch reported so far and showing its successful performance in 4310 Gb/s low-power and fast switching operation. The demonstration of the WDM...

  20. Theoretical model for plasma opening switch

    International Nuclear Information System (INIS)

    Baker, L.

    1980-07-01

    The theory of an explosive plasma switch is developed and compared with the experimental results of Pavlovskii and work at Sandia. A simple analytic model is developed, which predicts that such switches may achieve opening times of approximately 100 ns. When the switching time is limited by channel mixing it scales as t = C(m d 0 )/sup 1/2/P 0 2 P/sub e//sup -5/2/ where m is the foil mass per unit area, d 0 the channel thickness and P 0 the channel pressure (at explosive breakout), P/sub e/ the explosive pressure, C a constant of order 10 for c.g.s. units. Thus faster switching times may be achieved by minimizing foil mass and channel pressure, or increasing explosive product pressure, with the scaling exponents as shown suggesting that changes in pressures would be more effective

  1. Blood and Books: Performing Code Switching

    Directory of Open Access Journals (Sweden)

    Jeff Friedman

    2008-05-01

    Full Text Available Code switching is a linguistic term that identifies ways individuals use communication modes and registers to negotiate difference in social relations. This essay suggests that arts-based inquiry, in the form of choreography and performance, provides a suitable and efficacious location within which both verbal and nonverbal channels of code switching can be investigated. Blood and Books, a case study of dance choreography within the context of post-colonial Maori performance in Aotearoa/New Zealand, is described and analyzed for its performance of code switching. The essay is framed by a discussion of how arts-based research within tertiary higher education requires careful negotiation in the form of code switching, as performed by the author's reflexive use of vernacular and formal registers in the essay. URN: urn:nbn:de:0114-fqs0802462

  2. Error rate degradation due to switch crosstalk in large modular switched optical networks

    DEFF Research Database (Denmark)

    Saxtoft, Christian; Chidgey, P.

    1993-01-01

    A theoretical model of an optical network incorporating wavelength selective elements, amplifiers, couplers and switches is presented. The model is used to evaluate a large modular switch optical network that provides the capability of adapting easily to changes in network traffic requirements. T....... The network dimensions are shown to be limited by the optical crosstalk in the switch matrices and by the polarization dependent loss in the optical components...

  3. Optical Multidimensional Switching for Data Center Networks

    OpenAIRE

    Kamchevska, Valerija; Galili, Michael; Oxenløwe, Leif Katsuo; Berger, Michael Stübert

    2017-01-01

    Optical switches are known for the ability to provide high bandwidth connectivity at a relatively low power consumption and low latency. Several recent demonstrations on optical data center architectures confirm the potential for introducing all-optical switching within the data center, thus avoiding power hungry optical-electrical-optical conversions at each node. This Ph.D. thesis focuses precisely on the application of optical technologies in data center networks where optics is not only u...

  4. High voltage disconnect switch position monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Crampton, S W

    1983-08-01

    Unreliable position indication on high-voltage (HV) disconnect switches can result in equipment damage worth many times the cost of a disconnect switch. The benefits and limitations of a number of possible methods of reliably monitoring HV disconnect switches are assessed. Several methods of powering active devices at HV are noted. It is concluded that the most reliable way of monitoring switch position at reasonable cost would use a passive hermetically-sealed blade-position sensor located at HV, with a fibre-optic link between HV and ground. Separate sensors would be used for open and closed position indication. For maximum reliability the fibre-optic link would continue into the relay building. A passive magnetically actuated fibre-optic sensor has been built which demonstrates the feasibility of the concept. The sensor monitors blade position relative to the jaws in three dimensions with high resolution. A design for an improved passive magneto-optic sensor has significantly lower optical losses, allowing a single fibre-optic loop and 3 sensors to monitor closure of all phases of a disconnect switch. A similar loop would monitor switch opening. The improved sensor has a solid copper housing to provide greater immunity to fault currents, and to protect it from the environment and from physical damage. Two methods of providing a protected path for fibre-optics passing from HV to ground are proposed, one using a hollow porcelain switch-support insulator and the other using an additional small-diameter polymer insulator with optical fibres imbedded in its fibreglass core. A number of improvements are recommended which can be made to existing switches to increase their reliability. 16 refs., 13 figs., 1 tab.