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Sample records for apical junctional complexes

  1. Virus interaction with the apical junctional complex.

    Science.gov (United States)

    Gonzalez-Mariscal, Lorenza; Garay, Erika; Lechuga, Susana

    2009-01-01

    In order to infect pathogens must breach the epithelial barriers that separate the organism from the external environment or that cover the internal cavities and ducts of the body. Epithelia seal the passage through the paracellular pathway with the apical junctional complex integrated by tight and adherens junctions. In this review we describe how viruses like coxsackie, swine vesicular disease virus, adenovirus, reovirus, feline calcivirus, herpes viruses 1 and 2, pseudorabies, bovine herpes virus 1, poliovirus and hepatitis C use as cellular receptors integral proteins present at the AJC of epithelial cells. Interaction with these proteins contributes in a significant manner in defining the particular tropism of each virus. Besides these proteins, viruses exhibit a wide range of cellular co-receptors among which proteins present in the basolateral cell surface like integrins are often found. Therefore targeting proteins of the AJC constitutes a strategy that might allow viruses to bypass the physical barrier that blocks their access to receptors expressed on the basolateral surface of epithelial cells.

  2. Protein tyrosine phosphatase σ targets apical junction complex proteins in the intestine and regulates epithelial permeability.

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    Murchie, Ryan; Guo, Cong-Hui; Persaud, Avinash; Muise, Aleixo; Rotin, Daniela

    2014-01-14

    Protein tyrosine phosphatase (PTP)σ (PTPRS) was shown previously to be associated with susceptibility to inflammatory bowel disease (IBD). PTPσ(-/-) mice exhibit an IBD-like phenotype in the intestine and show increased susceptibility to acute models of murine colitis. However, the function of PTPσ in the intestine is uncharacterized. Here, we show an intestinal epithelial barrier defect in the PTPσ(-/-) mouse, demonstrated by a decrease in transepithelial resistance and a leaky intestinal epithelium that was determined by in vivo tracer analysis. Increased tyrosine phosphorylation was observed at the plasma membrane of epithelial cells lining the crypts of the small bowel and colon of the PTPσ(-/-) mouse, suggesting the presence of PTPσ substrates in these regions. Using mass spectrometry, we identified several putative PTPσ intestinal substrates that were hyper-tyrosine-phosphorylated in the PTPσ(-/-) mice relative to wild type. Among these were proteins that form or regulate the apical junction complex, including ezrin. We show that ezrin binds to and is dephosphorylated by PTPσ in vitro, suggesting it is a direct PTPσ substrate, and identified ezrin-Y353/Y145 as important sites targeted by PTPσ. Moreover, subcellular localization of the ezrin phosphomimetic Y353E or Y145 mutants were disrupted in colonic Caco-2 cells, similar to ezrin mislocalization in the colon of PTPσ(-/-) mice following induction of colitis. Our results suggest that PTPσ is a positive regulator of intestinal epithelial barrier, which mediates its effects by modulating epithelial cell adhesion through targeting of apical junction complex-associated proteins (including ezrin), a process impaired in IBD.

  3. Adherent-invasive Escherichia coli, strain LF82 disrupts apical junctional complexes in polarized epithelia

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    Ossa Juan C

    2009-08-01

    Full Text Available Abstract Background Although bacteria are implicated in the pathogenesis of chronic inflammatory bowel diseases (IBD, mechanisms of intestinal injury and immune activation remain unclear. Identification of adherent-invasive Escherichia coli (AIEC strains in IBD patients offers an opportunity to characterize the pathogenesis of microbial-induced intestinal inflammation in IBD. Previous studies have focused on the invasive phenotype of AIEC and the ability to replicate and survive in phagocytes. However, the precise mechanisms by which these newly identified microbes penetrate the epithelial lining remain to be clarified. Therefore, the aim of this study was to delineate the effects of AIEC, strain LF82 (serotype O83:H1 on model polarized epithelial monolayers as a contributor to intestinal injury in IBD. Results Infection of T84 and Madin-Darby Canine Kidney-I polarized epithelial cell monolayers with AIEC, strain LF82 led to a reduction in transepithelial electrical resistance and increased macromolecular (10 kilodalton dextran flux. Basolateral AIEC infection resulted in more severe disruption of the epithelial barrier. Increased permeability was accompanied by a redistribution of the tight junction adaptor protein, zonula occludens-1, demonstrated by confocal microscopy and formation of gaps between cells, as shown by transmission electron microscopy. After 4 h of infection of intestine 407 cells, bacteria replicated in the cell cytoplasm and were enclosed in membrane-bound vesicles positive for the late endosomal marker, LAMP1. Conclusion These findings indicate that AIEC, strain LF82 disrupts the integrity of the polarized epithelial cell barrier. This disruption enables bacteria to penetrate into the epithelium and replicate in the host cell cytoplasm. These findings provide important links between microbes related to IBD, the intestinal epithelial cell barrier and disease pathogenesis.

  4. Glutamine supplementation attenuates ethanol-induced disruption of apical junctional complexes in colonic epithelium and ameliorates gut barrier dysfunction and fatty liver in mice.

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    Chaudhry, Kamaljit K; Shukla, Pradeep K; Mir, Hina; Manda, Bhargavi; Gangwar, Ruchika; Yadav, Nikki; McMullen, Megan; Nagy, Laura E; Rao, RadhaKrishna

    2016-01-01

    Previous in vitro studies showed that glutamine (Gln) prevents acetaldehyde-induced disruption of tight junctions and adherens junctions in Caco-2 cell monolayers and human colonic mucosa. In the present study, we evaluated the effect of Gln supplementation on ethanol-induced gut barrier dysfunction and liver injury in mice in vivo. Ethanol feeding caused a significant increase in inulin permeability in distal colon. Elevated permeability was associated with a redistribution of tight junction and adherens junction proteins and depletion of detergent-insoluble fractions of these proteins, suggesting that ethanol disrupts apical junctional complexes in colonic epithelium and increases paracellular permeability. Ethanol-induced increase in colonic mucosal permeability and disruption of junctional complexes were most severe in mice fed Gln-free diet. Gln supplementation attenuated ethanol-induced mucosal permeability and disruption of tight junctions and adherens junctions in a dose-dependent manner, indicating the potential role of Gln in nutritional intervention to alcoholic tissue injury. Gln supplementation dose-dependently elevated reduced-protein thiols in colon without affecting the level of oxidized-protein thiols. Ethanol feeding depleted reduced protein thiols and elevated oxidized protein thiols. Ethanol-induced protein thiol oxidation was most severe in mice fed with Gln-free diet and absent in mice fed with Gln-supplemented diet, suggesting that antioxidant effect is one of the likely mechanisms involved in Gln-mediated amelioration of ethanol-induced gut barrier dysfunction. Ethanol feeding elevated plasma transaminase and liver triglyceride, which was accompanied by histopathologic lesions in the liver; ethanol-induced liver damage was attenuated by Gln supplementation. These results indicate that Gln supplementation ameliorates alcohol-induced gut and liver injury.

  5. Neisseria gonorrhoeae breaches the apical junction of polarized epithelial cells for transmigration by activating EGFR.

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    Edwards, Vonetta L; Wang, Liang-Chun; Dawson, Valerie; Stein, Daniel C; Song, Wenxia

    2013-06-01

    Neisseria gonorrhoeae initiates infection at the apical surface of columnar endocervical epithelial cells in the female reproductive tract. These cells provide a physical barrier against pathogens by forming continuous apical junctional complexes between neighbouring cells. This study examines the interaction of gonococci (GC) with polarized epithelial cells. We show that viable GC preferentially localize at the apical side of the cell-cell junction in polarized endometrial and colonic epithelial cells, HEC-1-B and T84. In GC-infected cells, continuous apical junctional complexes are disrupted, and the junction-associated protein β-catenin is redistributed from the apical junction to the cytoplasm and to GC adherent sites; however, overall cellular levels remain unchanged. This redistribution of junctional proteins is associated with a decrease in the 'fence' function of the apical junction but not its 'gate' function. Disruption of the apical junction by removing calcium increases GC transmigration across the epithelial monolayer. GC inoculation induces the phosphorylation of both epidermal growth factor receptor (EGFR) and β-catenin, while inhibition of EGFR kinase activity significantly reduces both GC-induced β-catenin redistribution and GC transmigration. Therefore, the gonococcus is capable of weakening the apical junction and polarity of epithelial cells by activating EGFR, which facilitates GC transmigration across the epithelium.

  6. Rho/Rho-associated Kinase-II Signaling Mediates Disassembly of Epithelial Apical Junctions

    OpenAIRE

    2007-01-01

    Apical junctional complex (AJC) plays a vital role in regulation of epithelial barrier function. Disassembly of the AJC is observed in diverse physiological and pathological states; however, mechanisms governing this process are not well understood. We previously reported that the AJC disassembly is driven by the formation of apical contractile acto-myosin rings. In the present study, we analyzed the signaling pathways regulating acto-myosin–dependent disruption of AJC by using a model of ext...

  7. A membrane fusion protein αSNAP is a novel regulator of epithelial apical junctions.

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    Nayden G Naydenov

    Full Text Available Tight junctions (TJs and adherens junctions (AJs are key determinants of the structure and permeability of epithelial barriers. Although exocytic delivery to the cell surface is crucial for junctional assembly, little is known about the mechanisms controlling TJ and AJ exocytosis. This study was aimed at investigating whether a key mediator of exocytosis, soluble N-ethylmaleimide sensitive factor (NSF attachment protein alpha (αSNAP, regulates epithelial junctions. αSNAP was enriched at apical junctions in SK-CO15 and T84 colonic epithelial cells and in normal human intestinal mucosa. siRNA-mediated knockdown of αSNAP inhibited AJ/TJ assembly and establishment of the paracellular barrier in SK-CO15 cells, which was accompanied by a significant down-regulation of p120-catenin and E-cadherin expression. A selective depletion of p120 catenin effectively disrupted AJ and TJ structure and compromised the epithelial barrier. However, overexpression of p120 catenin did not rescue the defects of junctional structure and permeability caused by αSNAP knockdown thereby suggesting the involvement of additional mechanisms. Such mechanisms did not depend on NSF functions or induction of cell death, but were associated with disruption of the Golgi complex and down-regulation of a Golgi-associated guanidine nucleotide exchange factor, GBF1. These findings suggest novel roles for αSNAP in promoting the formation of epithelial AJs and TJs by controlling Golgi-dependent expression and trafficking of junctional proteins.

  8. The Rho target PRK2 regulates apical junction formation in human bronchial epithelial cells.

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    Wallace, Sean W; Magalhaes, Ana; Hall, Alan

    2011-01-01

    Rho GTPases regulate multiple signaling pathways to control a number of cellular processes during epithelial morphogenesis. To investigate the downstream pathways through which Rho regulates epithelial apical junction formation, we screened a small interfering RNA (siRNA) library targeting 28 known Rho target proteins in 16HBE human bronchial epithelial cells. This led to the identification of the serine-threonine kinase PRK2 (protein kinase C-related kinase 2, also called PKN2). Depletion of PRK2 does not block the initial formation of primordial junctions at nascent cell-cell contacts but does prevent their maturation into apical junctions. PRK2 is recruited to primordial junctions, and this localization depends on its C2-like domain. Rho binding is essential for PRK2 function and also facilitates PRK2 recruitment to junctions. Kinase-dead PRK2 acts as a dominant-negative mutant and prevents apical junction formation. We conclude that PRK2 is recruited to nascent cell-cell contacts through its C2-like and Rho-binding domains and promotes junctional maturation through a kinase-dependent pathway.

  9. NMII forms a contractile transcellular sarcomeric network to regulate apical cell junctions and tissue geometry.

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    Ebrahim, Seham; Fujita, Tomoki; Millis, Bryan A; Kozin, Elliott; Ma, Xuefei; Kawamoto, Sachiyo; Baird, Michelle A; Davidson, Michael; Yonemura, Shigenobu; Hisa, Yasuo; Conti, Mary Anne; Adelstein, Robert S; Sakaguchi, Hirofumi; Kachar, Bechara

    2013-04-22

    Nonmuscle myosin II (NMII) is thought to be the master integrator of force within epithelial apical junctions, mediating epithelial tissue morphogenesis and tensional homeostasis. Mutations in NMII are associated with a number of diseases due to failures in cell-cell adhesion. However, the organization and the precise mechanism by which NMII generates and responds to tension along the intercellular junctional line are still not known. We discovered that periodic assemblies of bipolar NMII filaments interlace with perijunctional actin and α-actinin to form a continuous belt of muscle-like sarcomeric units (∼400-600 nm) around each epithelial cell. Remarkably, the sarcomeres of adjacent cells are precisely paired across the junctional line, forming an integrated, transcellular contractile network. The contraction/relaxation of paired sarcomeres concomitantly impacts changes in apical cell shape and tissue geometry. We show differential distribution of NMII isoforms across heterotypic junctions and evidence for compensation between isoforms. Our results provide a model for how NMII force generation is effected along the junctional perimeter of each cell and communicated across neighboring cells in the epithelial organization. The sarcomeric network also provides a well-defined target to investigate the multiple roles of NMII in junctional homeostasis as well as in development and disease. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Rab11 helps maintain apical crumbs and adherens junctions in the Drosophila embryonic ectoderm.

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    Jeremiah F Roeth

    Full Text Available BACKGROUND: Tissue morphogenesis and organogenesis require that cells retain stable cell-cell adhesion while changing shape and moving. One mechanism to accommodate this plasticity in cell adhesion involves regulated trafficking of junctional proteins. METHODOLOGY/PRINCIPAL FINDINGS: Here we explored trafficking of junctional proteins in two well-characterized model epithelia, the Drosophila embryonic ectoderm and amnioserosa. We find that DE-cadherin, the transmembrane protein of adherens junctions, is actively trafficked through putative vesicles, and appears to travel through both Rab5-positive and Rab11-positive structures. We manipulated the functions of Rab11 and Rab5 to examine the effects on junctional stability and morphogenesis. Reducing Rab11 function, either using a dominant negative construct or loss of function alleles, disrupts integrity of the ectoderm and leads to loss of adherens junctions. Strikingly, the apical junctional regulator Crumbs is lost before AJs are destabilized, while the basolateral protein Dlg remains cortical. Altering Rab5 function had less dramatic effects, not disrupting adherens junction integrity but affecting dorsal closure. CONCLUSIONS/SIGNIFICANCE: We contrast our results with what others saw when disrupting other trafficking regulators, and when disrupting Rab function in other tissues; together these data suggest distinct mechanisms regulate junctional stability and plasticity in different tissues.

  11. The Rho Target PRK2 Regulates Apical Junction Formation in Human Bronchial Epithelial Cells ▿

    OpenAIRE

    Wallace, Sean W.; Magalhaes, Ana; Hall, Alan

    2010-01-01

    Rho GTPases regulate multiple signaling pathways to control a number of cellular processes during epithelial morphogenesis. To investigate the downstream pathways through which Rho regulates epithelial apical junction formation, we screened a small interfering RNA (siRNA) library targeting 28 known Rho target proteins in 16HBE human bronchial epithelial cells. This led to the identification of the serine-threonine kinase PRK2 (protein kinase C-related kinase 2, also called PKN2). Depletion of...

  12. Actin-interacting protein 1 controls assembly and permeability of intestinal epithelial apical junctions.

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    Lechuga, Susana; Baranwal, Somesh; Ivanov, Andrei I

    2015-05-01

    Adherens junctions (AJs) and tight junctions (TJs) are crucial regulators of the integrity and restitution of the intestinal epithelial barrier. The structure and function of epithelial junctions depend on their association with the cortical actin cytoskeleton that, in polarized epithelial cells, is represented by a prominent perijunctional actomyosin belt. The assembly and stability of the perijunctional cytoskeleton is controlled by constant turnover (disassembly and reassembly) of actin filaments. Actin-interacting protein (Aip) 1 is an emerging regulator of the actin cytoskeleton, playing a critical role in filament disassembly. In this study, we examined the roles of Aip1 in regulating the structure and remodeling of AJs and TJs in human intestinal epithelium. Aip1 was enriched at apical junctions in polarized human intestinal epithelial cells and normal mouse colonic mucosa. Knockdown of Aip1 by RNA interference increased the paracellular permeability of epithelial cell monolayers, decreased recruitment of AJ/TJ proteins to steady-state intercellular contacts, and attenuated junctional reassembly in a calcium-switch model. The observed defects of AJ/TJ structure and functions were accompanied by abnormal organization and dynamics of the perijunctional F-actin cytoskeleton. Moreover, loss of Aip1 impaired the apico-basal polarity of intestinal epithelial cell monolayers and inhibited formation of polarized epithelial cysts in 3-D Matrigel. Our findings demonstrate a previously unanticipated role of Aip1 in regulating the structure and remodeling of intestinal epithelial junctions and early steps of epithelial morphogenesis.

  13. Differential regulation of the Hippo pathway by adherens junctions and apical-basal cell polarity modules.

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    Yang, Chih-Chao; Graves, Hillary K; Moya, Ivan M; Tao, Chunyao; Hamaratoglu, Fisun; Gladden, Andrew B; Halder, Georg

    2015-02-10

    Adherens junctions (AJs) and cell polarity complexes are key players in the establishment and maintenance of apical-basal cell polarity. Loss of AJs or basolateral polarity components promotes tumor formation and metastasis. Recent studies in vertebrate models show that loss of AJs or loss of the basolateral component Scribble (Scrib) cause deregulation of the Hippo tumor suppressor pathway and hyperactivation of its downstream effectors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). However, whether AJs and Scrib act through the same or independent mechanisms to regulate Hippo pathway activity is not known. Here, we dissect how disruption of AJs or loss of basolateral components affect the activity of the Drosophila YAP homolog Yorkie (Yki) during imaginal disc development. Surprisingly, disruption of AJs and loss of basolateral proteins produced very different effects on Yki activity. Yki activity was cell-autonomously decreased but non-cell-autonomously elevated in tissues where the AJ components E-cadherin (E-cad) or α-catenin (α-cat) were knocked down. In contrast, scrib knockdown caused a predominantly cell-autonomous activation of Yki. Moreover, disruption of AJs or basolateral proteins had different effects on cell polarity and tissue size. Simultaneous knockdown of α-cat and scrib induced both cell-autonomous and non-cell-autonomous Yki activity. In mammalian cells, knockdown of E-cad or α-cat caused nuclear accumulation and activation of YAP without overt effects on Scrib localization and vice versa. Therefore, our results indicate the existence of multiple, genetically separable inputs from AJs and cell polarity complexes into Yki/YAP regulation.

  14. Magi Is Associated with the Par Complex and Functions Antagonistically with Bazooka to Regulate the Apical Polarity Complex

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    Padash Barmchi, Mojgan; Samarasekera, Gayathri; Gilbert, Mary; Auld, Vanessa J.; Zhang, Bing

    2016-01-01

    The mammalian MAGI proteins play important roles in the maintenance of adherens and tight junctions. The MAGI family of proteins contains modular domains such as WW and PDZ domains necessary for scaffolding of membrane receptors and intracellular signaling components. Loss of MAGI leads to reduced junction stability while overexpression of MAGI can lead to increased adhesion and stabilization of epithelial morphology. However, how Magi regulates junction assembly in epithelia is largely unknown. We investigated the single Drosophila homologue of Magi to study the in vivo role of Magi in epithelial development. Magi is localized at the adherens junction and forms a complex with the polarity proteins, Par3/Bazooka and aPKC. We generated a Magi null mutant and found that Magi null mutants were viable with no detectable morphological defects even though the Magi protein is highly conserved with vertebrate Magi homologues. However, overexpression of Magi resulted in the displacement of Baz/Par3 and aPKC and lead to an increase in the level of PIP3. Interestingly, we found that Magi and Baz functioned in an antagonistic manner to regulate the localization of the apical polarity complex. Maintaining the balance between the level of Magi and Baz is an important determinant of the levels and localization of apical polarity complex. PMID:27074039

  15. Changes of the Unique Odontogenic Properties of Rat Apical Bud Cells under the Developing Apical Complex Microenvironment

    Institute of Scientific and Technical Information of China (English)

    Jun Fang; Liang Tang; Xiao-hui Liu; Ling-ying Wen; Yan Jin

    2009-01-01

    Aim To characterize the odontogenic capability of apical bud and phenotypical change of apical bud cells (ABCs) in different microenvironment. Methodology Incisor apical bud tissues from neonatal SD rat were dissected and transplanted into the renal capsules to determine their odontogenic capability. Meanwhile ABCs were cultured and purified by repeated differential trypsinization. Then ABCs were cultured with conditioned medium from developing apical complex cells (DAC-CM). Immunocytochemistry, reverse transcriptase polymerase chain reaction (RT-PCR) and scanning electron microscope (SEM) were performed to compare the biological change of ABC treated with or without DAC-CM. Results First we confirmed the ability of apical bud to form crown-like structure ectopically. Equally important, by using the developing apical complex (DAC) conditioned medium, we found the microenvironment created by root could abrogate the "crown" features of ABCs and promote their proliferation and differentiation. Conclusion ABCs possess odontogenic capability to form crown-like tissues and this property can be affected by root-produced microenvironment.

  16. The function of tight junctions in maintaining differences in lipid composition between the apical and the basolateral cell surface domains of MDCK cells

    NARCIS (Netherlands)

    van Meer, G.|info:eu-repo/dai/nl/068570368; Simons, K.

    1986-01-01

    Tight junctions in epithelial cells have been postulated to act as barriers inhibiting lateral diffusion of lipids and proteins between the apical and basolateral plasma membrane domains. To study the fence function of the tight junction in more detail, we have fused liposomes containing the

  17. Micro‐CT analyses of apical enlargement and molar root canal complexity

    DEFF Research Database (Denmark)

    Markvart, M.; Darvann, Tron Andre; Larsen, P.

    2012-01-01

    Markvart M, Darvann TA, Larsen P, Dalstra M, Kreiborg S, Bjørndal L. Micro‐CT analyses of apical enlargement and molar root canal complexity. International Endodontic Journal, 45, 273–281, 2012. Aim To compare the effectiveness of two rotary hybrid instrumentation techniques with focus on apical...

  18. Complex Polarity: Building Multicellular Tissues Through Apical Membrane Traffic.

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    Román-Fernández, Alvaro; Bryant, David M

    2016-12-01

    The formation of distinct subdomains of the cell surface is crucial for multicellular organism development. The most striking example of this is apical-basal polarization. What is much less appreciated is that underpinning an asymmetric cell surface is an equally dramatic intracellular endosome rearrangement. Here, we review the interplay between classical cell polarity proteins and membrane trafficking pathways, and discuss how this marriage gives rise to cell polarization. We focus on those mechanisms that regulate apical polarization, as this is providing a number of insights into how membrane traffic and polarity are regulated at the tissue level. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. The apical complex provides a regulated gateway for secretion of invasion factors in Toxoplasma.

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    Nicholas J Katris

    2014-04-01

    Full Text Available The apical complex is the definitive cell structure of phylum Apicomplexa, and is the focus of the events of host cell penetration and the establishment of intracellular parasitism. Despite the importance of this structure, its molecular composition is relatively poorly known and few studies have experimentally tested its functions. We have characterized a novel Toxoplasma gondii protein, RNG2, that is located at the apical polar ring--the common structural element of apical complexes. During cell division, RNG2 is first recruited to centrosomes immediately after their duplication, confirming that assembly of the new apical complex commences as one of the earliest events of cell replication. RNG2 subsequently forms a ring, with the carboxy- and amino-termini anchored to the apical polar ring and mobile conoid, respectively, linking these two structures. Super-resolution microscopy resolves these two termini, and reveals that RNG2 orientation flips during invasion when the conoid is extruded. Inducible knockdown of RNG2 strongly inhibits host cell invasion. Consistent with this, secretion of micronemes is prevented in the absence of RNG2. This block, however, can be fully or partially overcome by exogenous stimulation of calcium or cGMP signaling pathways, respectively, implicating the apical complex directly in these signaling events. RNG2 demonstrates for the first time a role for the apical complex in controlling secretion of invasion factors in this important group of parasites.

  20. Micro-CT analyses of apical enlargement and molar root canal complexity

    DEFF Research Database (Denmark)

    Markvart, Merete; Darvann, Tron Andre; Larsen, Per

    2012-01-01

    AIM: To compare the effectiveness of two rotary hybrid instrumentation techniques with focus on apical enlargement in molar teeth and to quantify and visualize spatial details of instrumentation efficacy in root canals of different complexity. METHODOLOGY: Maxillary and mandibular molar teeth wer...

  1. Trichomonas vaginalis perturbs the junctional complex in epithelial cells

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Trichomonas vaginalis, a protist parasite of the urogenital tract in humans, is the causative agent of trichomonosis,which in recent years have been associated with the cervical cancer development. In the present study we analyzed the modifications at the junctional complex level of Caco-2 cells after interaction with two isolates of T. vaginalis and the influence of the iron concentration present in the parasite's culture medium on the interaction effects. Our results show that T. vaginalis adheres to the epithelial cell causing alterations in the junctional complex, such as: (a) a decrease in transepithelial electrical resistance; (b) alteration in the pattern of junctional complex proteins distribution as obseryed for E-cadherin, occludin and ZO-1; and (c) enlargement of the spaces between epithelial cells. These effects were dependent on (a) the degree of the parasite virulence isolate, (b) the iron concentration in the culture medium, and (c) the expression of adhesin proteins on the parasite surface.

  2. Evolution and cell physiology. 4. Why invent yet another protein complex to build junctions in epithelial cells?

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    Le Bivic, André

    2013-12-15

    The formation of the first epithelium was an essential step for animal evolution, since it has allowed coordination of the behavior of a cell layer and creation of a selective barrier between the internal medium and the outside world. The possibility of coupling the cells in a single layer has allowed morphogenetic events, such as tube formation, or gastrulation, to form more complex animal morphologies. The invention of sealed junctions between cells has allowed, on the other hand, creation of an asymmetry of nutrients or salts between the apical and the basal side of the epithelial layer. Creation of an internal medium has led to homeostasis, allowing the evolution of more complex physiological functions and the emergence of sophisticated animal shapes. During evolution, the origins of the first animals coincided with the invention of several protein complexes, including true cadherins and the polarity protein complexes. How these complexes regulate formation of the apicolateral border and the adherens junctions is still not fully understood. This review focuses on the role of these apical polarity complexes and, in particular, the Crumbs complex, which is essential for proper organization of epithelial layers from Drosophila to humans.

  3. Implantation of a left ventricular assist device in patients with a complex apical anatomy.

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    Palmen, Meindert; Verwey, Harriette F; Haeck, Marlieke L A; Holman, Eduard R; Schalij, Martin J; Klautz, Robert J M

    2012-12-01

    Implantation of a left ventricular assist device can be challenging in patients with an altered apical anatomy after cardiac surgery or as the result of the presence of a calcified apical aneurysm. In this paper we present 2 cases with a challenging apical anatomy and introduce a new surgical technique facilitating left ventricular assist device implantation in these patients.

  4. Structural and functional insights into the malaria parasite moving junction complex.

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    Brigitte Vulliez-Le Normand

    Full Text Available Members of the phylum Apicomplexa, which include the malaria parasite Plasmodium, share many features in their invasion mechanism in spite of their diverse host cell specificities and life cycle characteristics. The formation of a moving junction (MJ between the membranes of the invading apicomplexan parasite and the host cell is common to these intracellular pathogens. The MJ contains two key parasite components: the surface protein Apical Membrane Antigen 1 (AMA1 and its receptor, the Rhoptry Neck Protein (RON complex, which is targeted to the host cell membrane during invasion. In particular, RON2, a transmembrane component of the RON complex, interacts directly with AMA1. Here, we report the crystal structure of AMA1 from Plasmodium falciparum in complex with a peptide derived from the extracellular region of PfRON2, highlighting clear specificities of the P. falciparum RON2-AMA1 interaction. The receptor-binding site of PfAMA1 comprises the hydrophobic groove and a region that becomes exposed by displacement of the flexible Domain II loop. Mutations of key contact residues of PfRON2 and PfAMA1 abrogate binding between the recombinant proteins. Although PfRON2 contacts some polymorphic residues, binding studies with PfAMA1 from different strains show that these have little effect on affinity. Moreover, we demonstrate that the PfRON2 peptide inhibits erythrocyte invasion by P. falciparum merozoites and that this strong inhibitory potency is not affected by AMA1 polymorphisms. In parallel, we have determined the crystal structure of PfAMA1 in complex with the invasion-inhibitory peptide R1 derived by phage display, revealing an unexpected structural mimicry of the PfRON2 peptide. These results identify the key residues governing the interactions between AMA1 and RON2 in P. falciparum and suggest novel approaches to antimalarial therapeutics.

  5. The effect of flowable materials on the microleakage of Class II composite restorations that extend apical to the cemento-enamel junction.

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    Sadeghi, Mostafa; Lynch, Christopher D

    2009-01-01

    This in vitro study investigated the effects of a thin layer of flowable composite or compomer on microleakage occurring in Class II packable and nanofilled composite restorations that extend apical to the cemento-enamel junction (CEJ). The current study also investigated any differences in microleakage that occur between restorations light-cured using a light-emitting diode (LED) and a quartz tungsten halogen (QTH) light-curing unit. Standardized Class II "slot" cavity preparations were prepared on the mesial and distal surfaces of 72 extracted, unrestored, non-carious premolars (n = 144). The gingival margins were placed 1 mm apical to the CEJ. The teeth were divided into two groups (n = 72) and restored with a "packable composite" (Filtek P60) or a "nano-filled composite" (Universal Filtek Supreme XT) with or without flowable composite (Flowable Filtek Supreme XT) or flowable composite (Dyract Flow) as gingival liners placed with thicknesses of 1.0 mm. Each increment was cured for 20 seconds before adding the next. One-half of the samples in each group was cured with QTH (Coltolux 75) and the other half with LED (Coltolux LED) LCUs. After a two-week incubation period at 37 degrees C, the specimens were thermocycled (5 degrees C-55 degrees C x 1500), immersed in 0.5% basic fuchsin dye for 24 hours, sectioned and the microleakage was then evaluated at the gingival margin by two examiners using a 0-3 score scale. Within the current study, when flowable liners were used, both the packable (Filtek P60) and nanofilled (Filtek Supreme XT Universal Restorative) composite materials had significantly less microleakage than when flowable liners were not used (p flowable liners (Flowable Filtek Supreme XT and Dyract Flow) resulted in a significant reduction of the microleakage occurring under both types of composite materials at the gingival floors ( p < 0.05), but there was no significant difference between them. The choice of light curing technology (LED vs QTH) had no

  6. Cholesterol depletion of enterocytes. Effect on the Golgi complex and apical membrane trafficking

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Niels-Christiansen, L L; Thorsen, Evy

    2000-01-01

    Intestinal brush border enzymes, including aminopeptidase N and sucrase-isomaltase, are associated with "rafts" (membrane microdomains rich in cholesterol and sphingoglycolipids). To assess the functional role of rafts in the present work, we studied the effect of cholesterol depletion on apical...... membrane trafficking in enterocytes. Cultured mucosal explants of pig small intestine were treated for 2 h with the cholesterol sequestering agent methyl-beta-cyclodextrin and lovastatin, an inhibitor of hydroxymethylglutaryl-coenzyme A reductase. The treatment reduced the cholesterol content >50...

  7. Indirect Magnetic Exchange between o-Iminosemiquinonate Ligands Controlled by Apical Substituent in Pentacoordinated Gallium(III) Complexes.

    Science.gov (United States)

    Piskunov, Alexander V; Ershova, Irina V; Bogomyakov, Artem S; Starikov, Andrey G; Fukin, Georgy K; Cherkasov, Vladimir K

    2015-07-06

    A number of pentacoordinated gallium complexes iSQ2GaR (1-7) (R = Et (1), Me (2), N3 (3), Cl (4), Br (5), I (6), NCS (7)) where iSQ is a radical anion of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-iminobenzoquinone were synthesized, and crystalline samples of 1-7 were characterized using magnetic susceptibility measurements. The character of magnetic exchange interaction between spins of o-iminosemiquinonate radicals was found to be strongly influenced by the nature of the apical substituent. The antiferromagnetic coupling is predominant when the apical position is occupied by halogens or other tested inorganic anions, and the value of exchange interaction parameter varies from -99 to -176 K for R = I and NCS, respectively. In the case of alkyl groups the ferromagnetic exchange prevails and, as the result, the triplet ground state for pentacoordianted biradical compounds was observed. Compounds 1-7 demonstrate a biradical X-band EPR spectrum in frozen toluene matrix. The molecular structures of 4, 6, and 7 have been established by single-crystal X-ray analysis. A computational DFT UB3LYP/6-31G(d,p) study was performed on complexes 1-7 in order to understand the reason for changes in the magnetic behavior of the related diradical gallium compounds. The calculations showed that the magnetic behavior of the complexes with inorganic anions is conditioned by the presence of antiferromagnetic exchange channel formed as a consequence of overlapping between donor atomic orbitals of iminoquinone with π-orbitals of halogen atoms (4-6) or nitrogen atom (3, 7).

  8. Apical cap

    Energy Technology Data Exchange (ETDEWEB)

    McLoud, T.C.; Isler, R.J.; Novelline, R.A.; Putman, C.E.; Simeone, J.; Stark, P.

    1981-08-01

    Apical caps, either unilateral or bilateral, are a common feature of advancing age and are usually the result of subpleural scarring unassociated with other diseases. Pancoast (superior sulcus) tumors are a well recognized cause of unilateral asymmetric apical density. Other lesions arising in the lung, pleura, or extrapleural space may produce unilateral or bilateral apical caps. These include: (1) inflammatory: tuberculosis and extrapleural abscesses extending from the neck; (2) post radiation fibrosis after mantle therapy for Hodgkin disease or supraclavicular radiation in the treatment of breast carcinoma; (3) neoplasm: lymphoma extending from the neck or mediastinum, superior sulcus bronchogenic carcinoma, and metastases; (4) traumatic: extrapleural dissection of blood from a ruptured aorta, fractures of the ribs or spine, or hemorrhage due to subclavian line placement; (5) vascular: coarctation of the aorta with dilated collaterals over the apex, fistula between the subclavian artery and vein; and (6) miscellaneous: mediastinal lipomatosis with subcostal fat extending over the apices.

  9. The apical complex protein Pals1 is required to maintain cerebellar progenitor cells in a proliferative state.

    Science.gov (United States)

    Park, Jun Young; Hughes, Lucinda J; Moon, Uk Yeol; Park, Raehee; Kim, Sang-Bae; Tran, Khoi; Lee, Ju-Seog; Cho, Seo-Hee; Kim, Seonhee

    2016-01-01

    Through their biased localization and function within the cell, polarity complex proteins are necessary to establish the cellular asymmetry required for tissue organization. Well-characterized germinal zones, mitogenic signals and cell types make the cerebellum an excellent model for addressing the crucial function of polarity complex proteins in the generation and organization of neural tissues. Deletion of the apical polarity complex protein Pals1 in the developing cerebellum results in a remarkably undersized cerebellum with disrupted layers in poorly formed folia and strikingly reduced granule cell production. We demonstrate that Pals1 is not only essential for cerebellum organogenesis, but also for preventing premature differentiation and thus maintaining progenitor pools in cerebellar germinal zones, including cerebellar granule neuron precursors in the external granule layer. In the Pals1 mouse mutants, the expression of genes that regulate the cell cycle was diminished, correlating with the loss of the proliferating cell population of germinal zones. Furthermore, enhanced Shh signaling through activated Smo cannot overcome impaired cerebellar cell generation, arguing for an epistatic role of Pals1 in proliferation capacity. Our study identifies Pals1 as a novel intrinsic factor that regulates the generation of cerebellar cells and Pals1 deficiency as a potential inhibitor of overactive mitogenic signaling.

  10. Unique cell type-specific junctional complexes in vascular endothelium of human and rat liver sinusoids.

    Directory of Open Access Journals (Sweden)

    Cyrill Géraud

    Full Text Available Liver sinusoidal endothelium is strategically positioned to control access of fluids, macromolecules and cells to the liver parenchyma and to serve clearance functions upstream of the hepatocytes. While clearance of macromolecular debris from the peripheral blood is performed by liver sinusoidal endothelial cells (LSECs using a delicate endocytic receptor system featuring stabilin-1 and -2, the mannose receptor and CD32b, vascular permeability and cell trafficking are controlled by transcellular pores, i.e. the fenestrae, and by intercellular junctional complexes. In contrast to blood vascular and lymphatic endothelial cells in other organs, the junctional complexes of LSECs have not yet been consistently characterized in molecular terms. In a comprehensive analysis, we here show that LSECs express the typical proteins found in endothelial adherens junctions (AJ, i.e. VE-cadherin as well as α-, β-, p120-catenin and plakoglobin. Tight junction (TJ transmembrane proteins typical of endothelial cells, i.e. claudin-5 and occludin, were not expressed by rat LSECs while heterogenous immunreactivity for claudin-5 was detected in human LSECs. In contrast, junctional molecules preferentially associating with TJ such as JAM-A, B and C and zonula occludens proteins ZO-1 and ZO-2 were readily detected in LSECs. Remarkably, among the JAMs JAM-C was considerably over-expressed in LSECs as compared to lung microvascular endothelial cells. In conclusion, we show here that LSECs form a special kind of mixed-type intercellular junctions characterized by co-occurrence of endothelial AJ proteins, and of ZO-1 and -2, and JAMs. The distinct molecular architecture of the intercellular junctional complexes of LSECs corroborates previous ultrastructural findings and provides the molecular basis for further analyses of the endothelial barrier function of liver sinusoids under pathologic conditions ranging from hepatic inflammation to formation of liver metastasis.

  11. Photocleavable junctions in complex polymer architectures and photoetchable thermoplastics

    Science.gov (United States)

    Sterner, Elizabeth Surles

    Polymer materials have become important tools in nanomanufacturing due to their facile processing and ready attainment of the necessary feature sizes. The development of cleavable junctions has led to advances in the production of polymer nanotemplates. Photocleavage strategies have come to the forefront of the field because photons, as a cleavage stimulus, do not have the mass-transport limitations of chemical methods, and provide for targeted two- and three-dimensional feature control. This dissertation presents a method for producing photocleavable materials by one-pot copper-catalyzed azide-alkyne "click" chemistry (CuAAC), activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and activated ester substitution methods that have each block labeled with a fluorescent dye, enabling exploration of the polymer physics of these systems by correlation fluorescence spectroscopy. It also introduces a novel photocleavable linker, the o-nitrobenzyl-1,2,3-triazole, its behavior on photocleavage, and a facile method for the production of the o-nitrobenzyl azides necessary for their synthesis. The synthesis and properties of a bulk photodegradable polytriazole are reported, as are proof of concept experiments demonstrating its potential as a directly photoetchable material. Lastly, this dissertation contains a perspective on possible avenues of new research on the topics presented.

  12. Impaired astrocytic gap junction coupling and potassium buffering in a mouse model of tuberous sclerosis complex.

    Science.gov (United States)

    Xu, Lin; Zeng, Ling-Hui; Wong, Michael

    2009-05-01

    Abnormalities in astrocytes occur in the brains of patients with Tuberous Sclerosis Complex (TSC) and may contribute to the pathogenesis of neurological dysfunction in this disease. Here, we report that knock-out mice with Tsc1 gene inactivation in glia (Tsc1(GFAP)CKO mice) exhibit decreased expression of the astrocytic connexin protein, Cx43, and an associated impairment in gap junction coupling between astrocytes. Correspondingly, hippocampal slices from Tsc1(GFAP)CKO mice have increased extracellular potassium concentration in response to stimulation. This impaired potassium buffering can be attributed to abnormal gap junction coupling, as a gap junction inhibitor elicits an additional increase in potassium concentration in control, but not Tsc1(GFAP)CKO slices. Furthermore, treatment with a mammalian target of rapamycin inhibitor reverses the deficient Cx43 expression and impaired potassium buffering. These findings suggest that Tsc1 inactivation in astrocytes causes defects in astrocytic gap junction coupling and potassium clearance, which may contribute to epilepsy in Tsc1(GFAP)CKO mice.

  13. Apical domain polarization localizes actin-myosin activity to drive ratchet-like apical constriction.

    Science.gov (United States)

    Mason, Frank M; Tworoger, Michael; Martin, Adam C

    2013-08-01

    Apical constriction promotes epithelia folding, which changes tissue architecture. During Drosophila gastrulation, mesoderm cells exhibit repeated contractile pulses that are stabilized such that cells apically constrict like a ratchet. The transcription factor Twist is required to stabilize cell shape. However, it is unknown how Twist spatially coordinates downstream signals to prevent cell relaxation. We find that during constriction, Rho-associated kinase (Rok) is polarized to the middle of the apical domain (medioapical cortex), separate from adherens junctions. Rok recruits or stabilizes medioapical myosin II (Myo-II), which contracts dynamic medioapical actin cables. The formin Diaphanous mediates apical actin assembly to suppress medioapical E-cadherin localization and form stable connections between the medioapical contractile network and adherens junctions. Twist is not required for apical Rok recruitment, but instead polarizes Rok medioapically. Therefore, Twist establishes radial cell polarity of Rok/Myo-II and E-cadherin and promotes medioapical actin assembly in mesoderm cells to stabilize cell shape fluctuations.

  14. The exon junction complex as a node of post-transcriptional networks.

    Science.gov (United States)

    Le Hir, Hervé; Saulière, Jérôme; Wang, Zhen

    2016-01-01

    The exon junction complex (EJC) is deposited onto mRNAs following splicing and adopts a unique structure, which can both stably bind to mRNAs and function as an anchor for diverse processing factors. Recent findings revealed that in addition to its established roles in nonsense-mediated mRNA decay, the EJC is involved in mRNA splicing, transport and translation. While structural studies have shed light on EJC assembly, transcriptome-wide analyses revealed differential EJC loading at spliced junctions. Thus, the EJC functions as a node of post-transcriptional gene expression networks, the importance of which is being revealed by the discovery of increasing numbers of EJC-related disorders.

  15. Carcinoembryonic antigen promotes colorectal cancer progression by targeting adherens junction complexes

    Energy Technology Data Exchange (ETDEWEB)

    Bajenova, Olga, E-mail: o.bazhenova@spbu.ru [Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); Chaika, Nina [Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); Tolkunova, Elena; Davydov-Sinitsyn, Alexander [Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064 (Russian Federation); Gapon, Svetlana [Boston Children' s Hospital, Boston, MA 02115 (United States); Thomas, Peter [Department of Surgery and Biomedical Sciences, Creighton University, Omaha, NE 68178 (United States); O’Brien, Stephen [Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg 199034 (Russian Federation)

    2014-06-10

    Oncomarkers play important roles in the detection and management of human malignancies. Carcinoembryonic antigen (CEA, CEACAM5) and epithelial cadherin (E-cadherin) are considered as independent tumor markers in monitoring metastatic colorectal cancer. They are both expressed by cancer cells and can be detected in the blood serum. We investigated the effect of CEA production by MIP101 colorectal carcinoma cell lines on E-cadherin adherens junction (AJ) protein complexes. No direct interaction between E-cadherin and CEA was detected; however, the functional relationships between E-cadherin and its AJ partners: α-, β- and p120 catenins were impaired. We discovered a novel interaction between CEA and beta-catenin protein in the CEA producing cells. It is shown in the current study that CEA overexpression alters the splicing of p120 catenin and triggers the release of soluble E-cadherin. The influence of CEA production by colorectal cancer cells on the function of E-cadherin junction complexes may explain the link between the elevated levels of CEA and the increase in soluble E-cadherin during the progression of colorectal cancer. - Highlights: • Elevated level of CEA increases the release of soluble E-cadherin during the progression of colorectal cancer. • CEA over-expression alters the binding preferences between E-cadherin and its partners: α-, β- and p120 catenins in adherens junction complexes. • CEA produced by colorectal cancer cells interacts with beta-catenin protein. • CEA over-expression triggers the increase in nuclear beta-catenin. • CEA over-expression alters the splicing of p120 catenin protein.

  16. Crystal structure of RuvC resolvase in complex with Holliday junction substrate.

    Science.gov (United States)

    Górecka, Karolina M; Komorowska, Weronika; Nowotny, Marcin

    2013-11-01

    The key intermediate in genetic recombination is the Holliday junction (HJ), a four-way DNA structure. At the end of recombination, HJs are cleaved by specific nucleases called resolvases. In Gram-negative bacteria, this cleavage is performed by RuvC, a dimeric endonuclease that belongs to the retroviral integrase superfamily. Here, we report the first crystal structure of RuvC in complex with a synthetic HJ solved at 3.75 Å resolution. The junction in the complex is in an unfolded 2-fold symmetrical conformation, in which the four arms point toward the vertices of a tetrahedron. The two scissile phosphates are located one nucleotide from the strand exchange point, and RuvC approaches them from the minor groove side. The key protein-DNA contacts observed in the structure were verified using a thiol-based site-specific cross-linking approach. Compared with known complex structures of the phage resolvases endonuclease I and endonuclease VII, the RuvC structure exhibits striking differences in the mode of substrate binding and location of the cleavage site.

  17. COMBINATION OF APICALLY POSITIONED AND CORONALLY ADVANCED FLAP IN THE TREATMENT OF A COMPLEX MUCOGINGIVAL AND RESTORATIVE PROBLEM. A 3-YEAR FOLLOW-UP. (Case Report

    Directory of Open Access Journals (Sweden)

    Kamen Kotsilkov

    2015-07-01

    Full Text Available INTRODUCTION: The modern Periodontology has various approaches to achieve a complete functional and aesthetic rehabilitation of the mucogingival complex. These techniques include application of flaps with apical or coronal advancement in order to achieve different treatment objectives. Complex cases with different pathology on adjacent teeth require several surgeries thereby increasing treatment time and patient discomfort. New combined approaches are needed to meet the challenges of such cases. OBJECTIVE: This report presents a case with a simultaneous application of a resective and a mucogingival technique in one dental sextant. METHODS: I.C. (36 with a localized chronic periodontitis, Miller Class I gingival recessions (13,14 and subgingival caries lesions (15,16. A combined approach with simultaneous crown lengthening with apically positioned flap for 16,15 and root coverage with enamel matrix derivate and a coronally advanced flap for 14,13 was applied in order to avoid multiple surgical procedures. RESULTS: On the third month after the surgical procedure a complete root coverage (13,14 was achieved. The crown lengthening procedure enabled the restoration of the caries lesions and the placement of new crowns (15,16. The result at the third year demonstrates a stable gingival margin with no recurrence of the gingival recessions. CONCLUSION: The applied combined procedure led to a complete resolution of the existing problems with a single surgery. The simultaneous application of different procedures seems a promising approach aimed to reduce the treatment time and to diminish patient discomfort.

  18. Creating complex molecular topologies by configuring DNA four-way junctions

    Science.gov (United States)

    Liu, Di; Chen, Gang; Akhter, Usman; Cronin, Timothy M.; Weizmann, Yossi

    2016-10-01

    The realization of complex topologies at the molecular level represents a grand challenge in chemistry. This necessitates the manipulation of molecular interactions with high precision. Here we show that single-stranded DNA (ssDNA) knots and links can be created by utilizing the inherent topological properties that pertain to the DNA four-way junction, at which the two helical strands form a node and can be configured conveniently and connected for complex topological construction. Using this strategy, we produced series of ssDNA topoisomers with the same sequences. By finely designing the curvature and torsion, double-stranded DNA knots were accessed by hybridizing and ligating the complementary strands with the knotted ssDNA templates. Furthermore, we demonstrate the use of a constructed ssDNA knot both to probe the topological conversion catalysed by DNA topoisomerase and to study the DNA replication under topological constraint.

  19. Structure of the exon junction core complex with a trapped DEAD-box ATPase bound to RNA

    DEFF Research Database (Denmark)

    Andersen, Christian Brix Folsted; Ballut, Lionel; Johansen, Jesper Sanderhoff;

    2006-01-01

    In higher eukaryotes, a multiprotein exon junction complex is deposited on spliced messenger RNAs. The complex is organized around a stable core, which serves as a binding platform for numerous factors that influence messenger RNA function. Here, we present the crystal structure of a tetrameric e...

  20. Soft versus hard junction formation for α-terthiophene molecular wires and their charge transfer complexes

    Science.gov (United States)

    Vezzoli, Andrea; Grace, Iain M.; Brooke, Carly; Nichols, Richard J.; Lambert, Colin J.; Higgins, Simon J.

    2017-03-01

    We used a range of scanning tunnelling microscopy (STM)-based methods to conduct a detailed study of single molecule junction conductance enhancement upon charge transfer complex formation, using bis(thiaalkyl)arene molecular wires as electron donors and tetracyanoethylene (TCNE) as an electron acceptor. Using the "hard" STM break junction (STM-BJ) method, in which a Au STM tip is pushed into a Au substrate and then withdrawn in the presence of molecules, we see a single, very broad, peak in the resulting conductance histogram when all data are used; the conductance enhancement is 25-fold for a terthiophene donor and 15-fold for a phenyl group. After rational data selection, in which only current-distance curves that contain a current plateau >0.2 nm long are used in the conductance histogram, three sharper peaks are resolved in the histograms for the charge transfer complexes; two substantially lower-conductance peaks are resolved for the uncomplexed molecules. Using the "soft" STM I(s) technique, in which initial contact between tip and substrate is avoided and the current limit is about an order of magnitude lower, we were able to resolve two peaks for the uncomplexed molecules depending upon the initial set point current (i.e., tip height), one at the same value as the lower of the two data-selected STM-BJ histogram peaks and an additional peak beyond the low-current limit for the STM-BJ experiment. For the terthiophene, the low, medium, and high conductance peaks for the TCNE complex are, respectively, ca. 70, 70, and 46 times higher in conductance than the corresponding peaks for the free molecule.

  1. Cochlear outer hair cells undergo an apical circumference remodeling constrained by the hair bundle shape.

    Science.gov (United States)

    Etournay, Raphaël; Lepelletier, Léa; Boutet de Monvel, Jacques; Michel, Vincent; Cayet, Nadège; Leibovici, Michel; Weil, Dominique; Foucher, Isabelle; Hardelin, Jean-Pierre; Petit, Christine

    2010-04-01

    Epithelial cells acquire diverse shapes relating to their different functions. This is particularly relevant for the cochlear outer hair cells (OHCs), whose apical and basolateral shapes accommodate the functioning of these cells as mechano-electrical and electromechanical transducers, respectively. We uncovered a circumferential shape transition of the apical junctional complex (AJC) of OHCs, which occurs during the early postnatal period in the mouse, prior to hearing onset. Geometric analysis of the OHC apical circumference using immunostaining of the AJC protein ZO1 and Fourier-interpolated contour detection characterizes this transition as a switch from a rounded-hexagon to a non-convex circumference delineating two lateral lobes at the neural side of the cell, with a negative curvature in between. This shape tightly correlates with the 'V'-configuration of the OHC hair bundle, the apical mechanosensitive organelle that converts sound-evoked vibrations into variations in cell membrane potential. The OHC apical circumference remodeling failed or was incomplete in all the mouse mutants affected in hair bundle morphogenesis that we tested. During the normal shape transition, myosin VIIa and myosin II (A and B isoforms) displayed polarized redistributions into and out of the developing lobes, respectively, while Shroom2 and F-actin transiently accumulated in the lobes. Defects in these redistributions were observed in the mutants, paralleling their apical circumference abnormalities. Our results point to a pivotal role for actomyosin cytoskeleton tensions in the reshaping of the OHC apical circumference. We propose that this remodeling contributes to optimize the mechanical coupling between the basal and apical poles of mature OHCs.

  2. Two Distinct MUS81-EME1 Complexes from Arabidopsis Process Holliday Junctions1[W

    Science.gov (United States)

    Geuting, Verena; Kobbe, Daniela; Hartung, Frank; Dürr, Jasmin; Focke, Manfred; Puchta, Holger

    2009-01-01

    The MUS81 endonuclease complex has been shown to play an important role in the repair of stalled or blocked replication forks and in the processing of meiotic recombination intermediates from yeast to humans. This endonuclease is composed of two subunits, MUS81 and EME1. Surprisingly, unlike other organisms, Arabidopsis (Arabidopsis thaliana) has two EME1 homologs encoded in its genome. AtEME1A and AtEME1B show 63% identity on the protein level. We were able to demonstrate that, after expression in Escherichia coli, each EME1 protein can assemble with the unique AtMUS81 to form a functional endonuclease. Both complexes, AtMUS81-AtEME1A and AtMUS81-AtEME1B, are not only able to cleave 3′-flap structures and nicked Holliday junctions (HJs) but also, with reduced efficiency, intact HJs. While the complexes have the same cleavage patterns with both nicked DNA substrates, slight differences in the processing of intact HJs can be detected. Our results are in line with an involvement of both MUS81-EME1 endonuclease complexes in DNA recombination and repair processes in Arabidopsis. PMID:19339504

  3. Two distinct MUS81-EME1 complexes from Arabidopsis process Holliday junctions.

    Science.gov (United States)

    Geuting, Verena; Kobbe, Daniela; Hartung, Frank; Dürr, Jasmin; Focke, Manfred; Puchta, Holger

    2009-06-01

    The MUS81 endonuclease complex has been shown to play an important role in the repair of stalled or blocked replication forks and in the processing of meiotic recombination intermediates from yeast to humans. This endonuclease is composed of two subunits, MUS81 and EME1. Surprisingly, unlike other organisms, Arabidopsis (Arabidopsis thaliana) has two EME1 homologs encoded in its genome. AtEME1A and AtEME1B show 63% identity on the protein level. We were able to demonstrate that, after expression in Escherichia coli, each EME1 protein can assemble with the unique AtMUS81 to form a functional endonuclease. Both complexes, AtMUS81-AtEME1A and AtMUS81-AtEME1B, are not only able to cleave 3'-flap structures and nicked Holliday junctions (HJs) but also, with reduced efficiency, intact HJs. While the complexes have the same cleavage patterns with both nicked DNA substrates, slight differences in the processing of intact HJs can be detected. Our results are in line with an involvement of both MUS81-EME1 endonuclease complexes in DNA recombination and repair processes in Arabidopsis.

  4. Complex wireframe DNA origami nanostructures with multi-arm junction vertices.

    Science.gov (United States)

    Zhang, Fei; Jiang, Shuoxing; Wu, Siyu; Li, Yulin; Mao, Chengde; Liu, Yan; Yan, Hao

    2015-09-01

    Structural DNA nanotechnology and the DNA origami technique, in particular, have provided a range of spatially addressable two- and three-dimensional nanostructures. These structures are, however, typically formed of tightly packed parallel helices. The development of wireframe structures should allow the creation of novel designs with unique functionalities, but engineering complex wireframe architectures with arbitrarily designed connections between selected vertices in three-dimensional space remains a challenge. Here, we report a design strategy for fabricating finite-size wireframe DNA nanostructures with high complexity and programmability. In our approach, the vertices are represented by n × 4 multi-arm junctions (n = 2-10) with controlled angles, and the lines are represented by antiparallel DNA crossover tiles of variable lengths. Scaffold strands are used to integrate the vertices and lines into fully assembled structures displaying intricate architectures. To demonstrate the versatility of the technique, a series of two-dimensional designs including quasi-crystalline patterns and curvilinear arrays or variable curvatures, and three-dimensional designs including a complex snub cube and a reconfigurable Archimedean solid were constructed.

  5. The endogenous Mus81-Eme1 complex resolves Holliday junctions by a nick and counternick mechanism.

    Science.gov (United States)

    Gaillard, Pierre-Henri L; Noguchi, Eishi; Shanahan, Paul; Russell, Paul

    2003-09-01

    Functional studies strongly suggest that the Mus81-Eme1 complex resolves Holliday junctions (HJs) in fission yeast, but in vitro it preferentially cleaves flexible three-way branched structures that model replication forks or 3' flaps. Here we report that a nicked HJ is the preferred substrate of endogenous and recombinant Mus81-Eme1. Cleavage occurs specifically on the strand that opposes the nick, resulting in resolution of the structure into linear duplex products. Resolving cuts made by the endogenous Mus81-Eme1 complex on an intact HJ are quasi-simultaneous, indicating that Mus81-Eme1 resolves HJs by a nick and counternick mechanism, with a large rate enhancement of the second cut arising from the flexible nature of the nicked HJ intermediate. Recombinant Mus81-Eme1 is ineffective at making the first cut. We also report that HJs accumulate in a DNA polymerase alpha mutant that lacks Mus81, providing further evidence that the Mus81-Eme1 complex targets HJs in vivo.

  6. Gap Junctions

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  7. Gap junctions.

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2012-07-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1853-1872, 2012.

  8. Disrupted Junctional Membrane Complexes and Hyperactive Ryanodine Receptors Following Acute Junctophilin Knockdown in Mice

    Science.gov (United States)

    van Oort, Ralph J.; Garbino, Alejandro; Wang, Wei; Dixit, Sayali S.; Landstrom, Andrew P.; Gaur, Namit; De Almeida, Angela C.; Skapura, Darlene G.; Rudy, Yoram; Burns, Alan R.; Ackerman, Michael J.; Wehrens, Xander H.T.

    2011-01-01

    Background Excitation-contraction coupling in striated muscle requires proper communication of plasmalemmal voltage-activated Ca2+ channels and Ca2+ release channels on sarcoplasmic reticulum (SR) within junctional membrane complexes (JMCs). Whereas previous studies revealed a loss of JMCs and embryonic lethality in germ-line junctophilin-2 (JPH2) knockout mice, it has remained unclear whether JPH2 plays an essential role in JMC formation and the Ca2+-induced Ca2+ release process in the heart. Our recent work demonstrated loss-of-function mutations in JPH2 in patients with hypertrophic cardiomyopathy. Methods and Results To elucidate the role of JPH2 in the heart, we developed a novel approach to conditionally reduce JPH2 protein levels using RNA interference. Cardiac-specific JPH2 knockdown resulted in impaired cardiac contractility, which caused heart failure and increased mortality. JPH2 deficiency resulted in loss of excitation-contraction coupling gain, precipitated by a reduction in the number of JMCs and increased variability in the plasmalemma-SR distance. Conclusions Loss of JPH2 had profound effects on Ca2+ release channel inactivation, suggesting a novel functional role for JPH2 in regulating intracellular Ca2+ release channels in cardiac myocytes. Thus, our novel approach of cardiac-specific shRNA-mediated knockdown of junctophilin-2 has uncovered a critical role for junctophilin in intracellular Ca2+ release in the heart. PMID:21339484

  9. A complex craniovertebral junction malformation in a patient with late onset glycogenosis 2

    Directory of Open Access Journals (Sweden)

    Mariasofia Cotelli

    2014-01-01

    Full Text Available Glycogenosis II (GSDII is an autosomal recessive lysosomal storage disorder resulting from deficiency of acid alpha-glucosidase and subsequent lysosomal accumulation of glycogen in skeletal, cardiac and smooth muscles. The late-onset form is characterized by wide variability of the phenotypical spectrum. Clinical findings may include muscle weakness, respiratory insufficiency, vascular abnormalities, low bone mineral density and higher risk of developing osteoporosis. Craniovertebral junction (CVJ malformations have never been described so far. We here report on a GSDII 43-year-old woman who harbored the mutations IVS1-13T>G and c.2237G>A in the acid alpha-glucosidase gene. She recurrently suffered from headache, neck pain and dizziness. Brain MRI and CT scan showed the presence of a very rare complex CVJ malformation composed of basilar invagination, basiocciput hypoplasia, partial C1 assimilation, C1 posterior arch aplasia and C1 lateral mass hypoplasia and offset. Although we cannot rule out their coincidental occurrence, the rarity of multiple CVJ malformations in the general population as well as the well-known GSDII multisystem involvement should suggest to study the CVJ in the diagnostic process of GSDII patients in order to assess the CVJ malformation frequency in GSDII population and verify a possible relationship between these two conditions.

  10. Complex sarcolemmal invaginations mimicking myotendinous junctions in a case of Laing early-onset distal myopathy.

    Science.gov (United States)

    Reis, Gerald F; de la Motte, Grant; Gooding, Rebecca; Laing, Nigel G; Margeta, Marta

    2015-12-01

    Distal myopathies are a group of clinically and pathologically overlapping muscle diseases that are genetically complex and can represent a diagnostic challenge. Laing early-onset distal myopathy (MPD1) is a form of distal myopathy caused by mutations in the MYH7 gene, which encodes the beta myosin heavy chain protein expressed in type 1 skeletal muscle fibers and cardiac myocytes. Here, we present a case of genetically confirmed MPD1 with a typical clinical presentation but distinctive light microscopic and ultrastructural findings on muscle biopsy. A 39-year-old professional male cellist presented with a bilateral foot drop that developed by age 8; analysis of the family pedigree showed an autosomal dominant pattern of inheritance. The physical exam demonstrated bilateral weakness of ankle dorsiflexors, toe extensors and finger extensors; creatine kinase level was normal. Biopsy of the quadriceps femoris muscle showed predominance and hypotrophy of type 1 fibers, hybrid fibers with co-expression of slow and fast myosin proteins (both in highly atrophic and normal size range), moth-eaten fibers and mini-cores, lack of rimmed vacuoles and rare desmin-positive eosinophilic sarcoplasmic inclusions. In addition to these abnormalities often observed in MPD1, the biopsy demonstrated frequent clefted fibers with complex sarcolemmal invaginations; on ultrastructural examination, these structures closely mimicked myotendinous junctions but were present away from the tendon and were almost exclusively found in type 1 fibers. Sequencing analysis of the MYH7 gene in the index patient and other affected family members demonstrated a previously described heterozygous c.4522_4524delGAG (p.Glu1508del) mutation. This case widens the pathologic spectrum of MPD1 and highlights the pathologic and clinical variability that can accompany the same genetic mutation, suggesting a significant role for modifier genes in MPD1 pathogenesis. © 2015 Japanese Society of Neuropathology.

  11. XAANTAL2 (AGL14) Is an Important Component of the Complex Gene Regulatory Network that Underlies Arabidopsis Shoot Apical Meristem Transitions.

    Science.gov (United States)

    Pérez-Ruiz, Rigoberto V; García-Ponce, Berenice; Marsch-Martínez, Nayelli; Ugartechea-Chirino, Yamel; Villajuana-Bonequi, Mitzi; de Folter, Stefan; Azpeitia, Eugenio; Dávila-Velderrain, José; Cruz-Sánchez, David; Garay-Arroyo, Adriana; Sánchez, María de la Paz; Estévez-Palmas, Juan M; Álvarez-Buylla, Elena R

    2015-05-01

    In Arabidopsis thaliana, multiple genes involved in shoot apical meristem (SAM) transitions have been characterized, but the mechanisms required for the dynamic attainment of vegetative, inflorescence, and floral meristem (VM, IM, FM) cell fates during SAM transitions are not well understood. Here we show that a MADS-box gene, XAANTAL2 (XAL2/AGL14), is necessary and sufficient to induce flowering, and its regulation is important in FM maintenance and determinacy. xal2 mutants are late flowering, particularly under short-day (SD) condition, while XAL2 overexpressing plants are early flowering, but their flowers have vegetative traits. Interestingly, inflorescences of the latter plants have higher expression levels of LFY, AP1, and TFL1 than wild-type plants. In addition we found that XAL2 is able to bind the TFL1 regulatory regions. On the other hand, the basipetal carpels of the 35S::XAL2 lines lose determinacy and maintain high levels of WUS expression under SD condition. To provide a mechanistic explanation for the complex roles of XAL2 in SAM transitions and the apparently paradoxical phenotypes of XAL2 and other MADS-box (SOC1, AGL24) overexpressors, we conducted dynamic gene regulatory network (GRN) and epigenetic landscape modeling. We uncovered a GRN module that underlies VM, IM, and FM gene configurations and transition patterns in wild-type plants as well as loss and gain of function lines characterized here and previously. Our approach thus provides a novel mechanistic framework for understanding the complex basis of SAM development. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.

  12. An Important Member of Tight Junctions: Claudins

    Directory of Open Access Journals (Sweden)

    Ozlem Demirpence

    2016-01-01

    Full Text Available The tight junction (TJs, the most apically located of the intercellular junctional complexes, inhibits solute and water flow through the paracellular space, termed the %u201Cbarrier%u201D function. TJs participate in signal transduction mechanisms that regulate epithelial cell proliferation, gene expression, differentiation and morphogenesis. The claudin family of transmembrane proteins localized to the TJ. Loss of expression of Claudin causes of suppression TJs function. Recent studies have shown that altered levels of the different claudins may be related to invasion and progression of carcinoma cells in several primary neoplasms. A better knowledge of the mechanisms underlying carcinogenesis will likely result in the development of novel approaches for the diagnosis and therapy.

  13. Connexin26 regulates assembly and maintenance of cochlear gap junction macromolecular complex for normal hearing

    Science.gov (United States)

    Kamiya, Kazusaku; Fukunaga, Ichiro; Hatakeyama, Kaori; Ikeda, Katsuhisa

    2015-12-01

    Hereditary deafness affects about 1 in 2000 children and GJB2 gene mutation is most frequent cause for this disease in the world. GJB2 encodes connexin26 (Cx26), a component in cochlear gap junction. Recently, we found macromolecular change of gap junction plaques with two different types of Cx26 mutation as major classification of clinical case, one is a model of dominant negative type, Cx26R75W+ and the other is conditional gene deficient mouse, Cx26f/fP0Cre as a model for insufficiency of gap junction protein [6]. Gap junction composed mainly of Cx26 and Cx30 in wild type mice formed large planar gap junction plaques (GJP). In contrast, Cx26R75W+ and Cx26f/fP0Cre showed fragmented small round GJPs around the cell border. In Cx26f/fP0Cre, some of the cells with Cx26 expression due to their cellular mosaicism showed normal large GJP with Cx26 and Cx30 only at the cell junction site between two Cx26 positive cells. These indicate that bilateral Cx26 expressions from both adjacent cells are essential for the formation of the cochlear linear GJP, and it is not compensated by other cochlear Connexins such as Connexin30. In the present study, we demonstrated a new molecular pathology in most common hereditary deafness with different types of Connexin26 mutations, and this machinery can be a new target for drag design of hereditary deafness.

  14. A Negative Feedback Loop Controlling bHLH Complexes Is Involved in Vascular Cell Division and Differentiation in the Root Apical Meristem.

    Science.gov (United States)

    Katayama, Hirofumi; Iwamoto, Kuninori; Kariya, Yuka; Asakawa, Tomohiro; Kan, Toshiyuki; Fukuda, Hiroo; Ohashi-Ito, Kyoko

    2015-12-07

    Controlling cell division and differentiation in meristems is essential for proper plant growth. Two bHLH heterodimers consisting of LONESOME HIGHWAY (LHW) and TARGET OF MONOPTEROS 5 (TMO5)/TMO5-LIKE1 (T5L1) regulate periclinal cell division in vascular cells in the root apical meristem (RAM). In this study, we further investigated the functions of LHW-T5L1, finding that in addition to controlling cell division, this complex regulates xylem differentiation in the RAM via a novel negative regulatory system. LHW-T5L1 upregulated the thermospermine synthase gene ACAULIS5 (ACL5), as well as SUPPRESSOR OF ACAULIS5 LIKE3 (SACL3), which encodes a bHLH protein, in the RAM. The SACL3 promoter sequence contains a conserved upstream open reading frame (uORF), which blocked translation of the main SACL3 ORF in the absence of thermospermine. Thermospermine eliminated the negative effect of uORF and enhanced SACL3 production. Further genetic and molecular biological analyses indicated that ACL5 and SACL3 suppress the function of LHW-T5L1 through a protein-protein interaction between LHW and SACL3. Finally, we showed that a negative feedback loop consisting of LHW-T5L1, ACL5, SACL3, and LHW-SACL3 contributes to maintain RAM size and proper root growth. These findings suggest that a negative feedback loop regulates the LHW-T5L1 output level to coordinate cell division and differentiation in a cell-autonomous manner. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Studies of aberrant phyllotaxy1 mutants of maize indicate complex interactions between auxin and cytokinin signaling in the shoot apical meristem.

    Science.gov (United States)

    Lee, Byeong-ha; Johnston, Robyn; Yang, Yan; Gallavotti, Andrea; Kojima, Mikiko; Travençolo, Bruno A N; Costa, Luciano da F; Sakakibara, Hitoshi; Jackson, David

    2009-05-01

    One of the most fascinating aspects of plant morphology is the regular geometric arrangement of leaves and flowers, called phyllotaxy. The shoot apical meristem (SAM) determines these patterns, which vary depending on species and developmental stage. Auxin acts as an instructive signal in leaf initiation, and its transport has been implicated in phyllotaxy regulation in Arabidopsis (Arabidopsis thaliana). Altered phyllotactic patterns are observed in a maize (Zea mays) mutant, aberrant phyllotaxy1 (abph1, also known as abphyl1), and ABPH1 encodes a cytokinin-inducible type A response regulator, suggesting that cytokinin signals are also involved in the mechanism by which phyllotactic patterns are established. Therefore, we investigated the interaction between auxin and cytokinin signaling in phyllotaxy. Treatment of maize shoots with a polar auxin transport inhibitor, 1-naphthylphthalamic acid, strongly reduced ABPH1 expression, suggesting that auxin or its polar transport is required for ABPH1 expression. Immunolocalization of the PINFORMED1 (PIN1) polar auxin transporter revealed that PIN1 expression marks leaf primordia in maize, similarly to Arabidopsis. Interestingly, maize PIN1 expression at the incipient leaf primordium was greatly reduced in abph1 mutants. Consistently, auxin levels were reduced in abph1, and the maize PIN1 homolog was induced not only by auxin but also by cytokinin treatments. Our results indicate distinct roles for ABPH1 as a negative regulator of SAM size and a positive regulator of PIN1 expression. These studies highlight a complex interaction between auxin and cytokinin signaling in the specification of phyllotactic patterns and suggest an alternative model for the generation of altered phyllotactic patterns in abph1 mutants. We propose that reduced auxin levels and PIN1 expression in abph1 mutant SAMs delay leaf initiation, contributing to the enlarged SAM and altered phyllotaxy of these mutants.

  16. Studies of aberrant phyllotaxy1 Mutants of Maize Indicate Complex Interactions between Auxin and Cytokinin Signaling in the Shoot Apical Meristem1[W][OA

    Science.gov (United States)

    Lee, Byeong-ha; Johnston, Robyn; Yang, Yan; Gallavotti, Andrea; Kojima, Mikiko; Travençolo, Bruno A.N.; Costa, Luciano da F.; Sakakibara, Hitoshi; Jackson, David

    2009-01-01

    One of the most fascinating aspects of plant morphology is the regular geometric arrangement of leaves and flowers, called phyllotaxy. The shoot apical meristem (SAM) determines these patterns, which vary depending on species and developmental stage. Auxin acts as an instructive signal in leaf initiation, and its transport has been implicated in phyllotaxy regulation in Arabidopsis (Arabidopsis thaliana). Altered phyllotactic patterns are observed in a maize (Zea mays) mutant, aberrant phyllotaxy1 (abph1, also known as abphyl1), and ABPH1 encodes a cytokinin-inducible type A response regulator, suggesting that cytokinin signals are also involved in the mechanism by which phyllotactic patterns are established. Therefore, we investigated the interaction between auxin and cytokinin signaling in phyllotaxy. Treatment of maize shoots with a polar auxin transport inhibitor, 1-naphthylphthalamic acid, strongly reduced ABPH1 expression, suggesting that auxin or its polar transport is required for ABPH1 expression. Immunolocalization of the PINFORMED1 (PIN1) polar auxin transporter revealed that PIN1 expression marks leaf primordia in maize, similarly to Arabidopsis. Interestingly, maize PIN1 expression at the incipient leaf primordium was greatly reduced in abph1 mutants. Consistently, auxin levels were reduced in abph1, and the maize PIN1 homolog was induced not only by auxin but also by cytokinin treatments. Our results indicate distinct roles for ABPH1 as a negative regulator of SAM size and a positive regulator of PIN1 expression. These studies highlight a complex interaction between auxin and cytokinin signaling in the specification of phyllotactic patterns and suggest an alternative model for the generation of altered phyllotactic patterns in abph1 mutants. We propose that reduced auxin levels and PIN1 expression in abph1 mutant SAMs delay leaf initiation, contributing to the enlarged SAM and altered phyllotaxy of these mutants. PMID:19321707

  17. Endocytosis and Recycling of Tight Junction Proteins in Inflammation

    Directory of Open Access Journals (Sweden)

    Markus Utech

    2010-01-01

    Full Text Available A critical function of the epithelial lining is to form a barrier that separates luminal contents from the underlying interstitium. This barrier function is primarily regulated by the apical junctional complex (AJC consisting of tight junctions (TJs and adherens junctions (AJs and is compromised under inflammatory conditions. In intestinal epithelial cells, proinflammatory cytokines, for example, interferon-gamma (IFN-γ, induce internalization of TJ proteins by endocytosis. Endocytosed TJ proteins are passed into early and recycling endosomes, suggesting the involvement of recycling of internalized TJ proteins. This review summarizes mechanisms by which TJ proteins under inflammatory conditions are internalized in intestinal epithelial cells and point out comparable mechanism in nonintestinal epithelial cells.

  18. Hepatocyte growth factor activator inhibitor-1 has a complex subcellular itinerary

    DEFF Research Database (Denmark)

    Godiksen, Sine; Selzer-Plon, Joanna; Pedersen, Esben D K;

    2008-01-01

    it is a key regulator of carcinogenesis. HAI-1 is expressed in polarized epithelial cells, which have the plasma membrane divided by tight junctions into an apical and a basolateral domain. In the present study we show that HAI-1 at steady-state is mainly located on the basolateral membrane of both Madin...... in transporting matriptase as a matriptase-HAI-1 complex from the basolateral plama membrane to the apical plasma membrane, as matriptase is known to interact with prostasin, located at the apical plasma membrane....... and then recycles between the basolateral plasma membrane and endosomes for hours until it is transcytosed to the apical plasma membrane. Minor amounts of HAI-1 present at the apical plasma membrane are proteolytically cleaved and released into the apical medium. Full-length membrane-bound HAI-1 has a half...

  19. Dual Interaction of JAM-C with JAM-B and αMβ2 Integrin: Function in Junctional Complexes and Leukocyte AdhesionD⃞

    OpenAIRE

    Lamagna, Chrystelle; Meda, Paolo; Mandicourt, Guillaume; Brown, James; Gilbert, Robert J C; Jones, E Yvonne; Kiefer, Friedemann; Ruga, Pilar; Imhof, Beat A.; Aurrand-Lions, Michel

    2005-01-01

    The junctional adhesion molecules (JAMs) have been recently described as interendothelial junctional molecules and as integrin ligands. Here we show that JAM-B and JAM-C undergo heterophilic interaction in cell-cell contacts and that JAM-C is recruited and stabilized in junctional complexes by JAM-B. In addition, soluble JAM-B dissociates soluble JAM-C homodimers to form JAM-B/JAM-C heterodimers. This suggests that the affinity of JAM-C monomers to form dimers is higher for JAM-B than for JAM...

  20. Left ventricular apical diseases.

    Science.gov (United States)

    Cisneros, Silvia; Duarte, Ricardo; Fernandez-Perez, Gabriel C; Castellon, Daniel; Calatayud, Julia; Lecumberri, Iñigo; Larrazabal, Eneritz; Ruiz, Berta Irene

    2011-08-01

    There are many disorders that may involve the left ventricular (LV) apex; however, they are sometimes difficult to differentiate. In this setting cardiac imaging methods can provide the clue to obtaining the diagnosis. The purpose of this review is to illustrate the spectrum of diseases that most frequently affect the apex of the LV including Tako-Tsubo cardiomyopathy, LV aneurysms and pseudoaneurysms, apical diverticula, apical ventricular remodelling, apical hypertrophic cardiomyopathy, LV non-compaction, arrhythmogenic right ventricular dysplasia with LV involvement and LV false tendons, with an emphasis on the diagnostic criteria and imaging features. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13244-011-0091-6) contains supplementary material, which is available to authorized users.

  1. Deoxynivanelol and Fumonisin, Alone or in Combination, Induce Changes on Intestinal Junction Complexes and in E-Cadherin Expression

    Directory of Open Access Journals (Sweden)

    Karina Basso

    2013-11-01

    Full Text Available Fusariotoxins such as fumonisin B1 (FB1 and deoxynivalenol (DON cause deleterious effects on the intestine of pigs. The aim of this study was to evaluate the effect of these mycotoxins, alone and in combination, on jejunal explants from piglets, using histological, immunohistochemical and ultrastructural assays. Five 24-day old pigs were used for sampling the explants. Forty-eight explants were sampled from each animal. Explants were incubated for 4 hours in culture medium and medium containing FB1 (100 µM, DON (10 µM and both mycotoxins (100 µM FB1 plus 10 µM DON. Exposure to all treatments induced a significant decrease in the normal intestinal morphology and in the number of goblet cells, which were more severe in explants exposed to DON and both mycotoxins. A significant reduction in villus height occurred in groups treated with DON and with co-contamination. Expression of E-cadherin was significantly reduced in explants exposed to FB1 (40%, DON (93% and FB1 plus DON (100%. The ultrastructural assay showed increased intercellular spaces and no junction complexes on enterocytes exposed to mycotoxins. The present data indicate that FB1 and DON induce changes in cell junction complexes that could contribute to increase paracellular permeability. The ex vivo model was adequate for assessing intestinal toxicity induced by exposure of isolated or associated concentrations of 100 µM of FB1 and 10 µM of DON.

  2. Managing the complexity of communication: regulation of gap junctions by post-translational modification

    DEFF Research Database (Denmark)

    Axelsen, Lene Nygaard; Callø, Kirstine; von Holstein-Rathlou, Niels-Henrik

    2013-01-01

    expression by transcription and translation is of great importance, the trafficking, channel activity and degradation are also under tight control. The function of connexins can be regulated by several post translational modifications, which affect numerous parameters; including number of channels, open......Gap junctions are comprised of connexins that form cell-to-cell channels which couple neighboring cells to accommodate the exchange of information. The need for communication does, however, change over time and therefore must be tightly controlled. Although the regulation of connexin protein...... probability, single channel conductance or selectivity. The most extensively investigated post translational modifications are phosphorylations, which have been documented in all mammalian connexins. Besides phosphorylations, some connexins are known to be ubiquitinated, SUMOylated, nitrosylated, hydroxylated...

  3. Density functional theory study on Herzberg-Teller contribution in Raman scattering from 4-aminothiophenol-metal complex and metal-4-aminothiophenol-metal junction

    Science.gov (United States)

    Liu, Shasha; Zhao, Xiuming; Li, Yuanzuo; Zhao, Xiaohong; Chen, Maodu

    2009-06-01

    Density functional theory (DFT) and time-dependent DFT calculations have been performed to investigate the Raman scattering spectra of metal-molecule complex and metal-molecule-metal junction architectures interconnected with 4-aminothiophenol (PATP) molecule. The simulated profiles of normal Raman scattering (NRS) spectra for the two complexes (Ag2-PATP and PATP-Au2) and the two junctions (Ag2-PATP-Au2 and Au2-PATP-Ag2) are similar to each other, but exhibit obviously different Raman intensities. Due to the lager static polarizabilities of the two junctions, which directly influence the ground state chemical enhancement in NRS spectra, the calculated normal Raman intensities of them are stronger than those of two complexes by the factor of 102. We calculate preresonance Raman scattering (RRS) spectra with incident light at 1064 nm, which is much lower than the S1 electronic transition energy of complexes and junctions. Ag2-PATP-Au2 and Au2-PATP-Ag2 junctions yield higher Raman intensities than those of Ag2-PATP and PATP-Au2 complexes, especially for b2 modes. This effect is mainly attributed to charge transfer (CT) between the metal gap and the PAPT molecule which results in the occurrence of CT resonance enhancement. The calculated pre-RRS spectra strongly depend on the electronic transition state produced by new structures. With excitation at 514.5 nm, the calculated pre-RRS spectra of two complexes and two junctions are stronger than those of with excitation at 1064 nm. A charge difference densities methodology has been used to visually describe chemical enhancement mechanism of RRS spectrum. This methodology aims at visualizing intermolecular CT which provides direct evidence of the Herzberg-Teller mechanism.

  4. Development of a Symmetric Ring Junction as a Four-Port Reflectometer for Complex Reflection Coefficient Measurements

    Directory of Open Access Journals (Sweden)

    K.Y. Lee

    2015-12-01

    Full Text Available Six-port reflectometer is well-known for its ability to measure magnitude and phase-shift of microwave signal using four power detectors that perform magnitude-only measurements. This paper presents the development of an innovative symmetric ring junction as four-port reflectometer for complex reflection coefficient measurements. It reduces the number of required detectors to two. Design optimization, new calibration modeling and algorithm are discussed in details for this four-port reflectometer. The developed four-port reflectometer is compared to five-port reflectometer and vector network analyzer. It is found that the measured magnitude and phase-shift shows good performance in comparison with the commercial vector network analyzer and the five-port reflectometer.

  5. Study of guided wave transmission through complex junction in sodium cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Elie, Q.; Le Bourdais, F.; Jezzine, K.; Baronian, V. [Non Destructive Testing Department at the French Atomic Energy Commission (CEA), Saclay, 91191 Gif sur Yvette CEDEX, (France)

    2015-07-01

    Ultrasonic guided wave techniques are seen as suitable candidates for the inspection of welded structures within sodium cooled fast reactors (SFR), as the long range propagation of guided waves without amplitude attenuation can overcome the accessibility problem due to the liquid sodium. In the context of the development of the Advanced Sodium Test Reactor for Industrial Demonstration (ASTRID), the French Atomic Commission (CEA) investigates non-destructive testing techniques based on guided wave propagation. In this work, guided wave NDT methods are applied to control the integrity of welds located in a junction-type structure welded to the main vessel. The method presented in this paper is based on the analysis of scattering matrices peculiar to each expected defect, and takes advantage of the multi-modal and dispersive characteristics of guided wave generation. In a simulation study, an algorithm developed using the CIVA software is presented. It permits selecting appropriate incident modes to optimize detection and identification of expected flawed configurations. In the second part of this paper, experimental results corresponding to a first validation step of the simulation results are presented. The goal of the experiments is to estimate the effectiveness of the incident mode selection in plates. The results show good agreement between experience and simulation. (authors)

  6. [Apical endodontic surgery].

    Science.gov (United States)

    Lindeboom, J A

    2004-04-01

    If (a revision of) a conventional endodontic treatment is not possible or not successful, apical endodontic surgery can be indicated. The contemporary indications, the better retrograde preparation techniques with ultrasonic retro-tips, and the better visualisation of the operation area with an operation microscope can lead to higher success percentages. Moreover, the current developments in the field of compatible filling materials are promising. Also the application of lasers is promising, but has still to prove its clinical usefulness.

  7. Compound inheritance of a low-frequency regulatory SNP and a rare null mutation in exon-junction complex subunit RBM8A causes TAR syndrome

    NARCIS (Netherlands)

    Albers, C.A.; Paul, D.S.; Schulze, H.; Freson, K.; Stephens, J.C.; Smethurst, P.A.; Jolley, J.D.; Cvejic, A.; Kostadima, M.; Bertone, P.; Breuning, M.H.; Debili, N.; Deloukas, P.; Favier, R.; Fiedler, J.; Hobbs, C.M.; Huang, N.; Hurles, M.E.; Kiddle, G.; Krapels, I.; Nurden, P.; Ruivenkamp, C.A.; Sambrook, J.G.; Smith, K.; Stemple, D.L.; Strauss, G.; Thys, C.; Geet, C. van; Newbury-Ecob, R.; Ouwehand, W.H.; Ghevaert, C.

    2012-01-01

    The exon-junction complex (EJC) performs essential RNA processing tasks. Here, we describe the first human disorder, thrombocytopenia with absent radii (TAR), caused by deficiency in one of the four EJC subunits. Compound inheritance of a rare null allele and one of two low-frequency SNPs in the reg

  8. Mystery in genetics: PUB4 gives a clue to the complex mechanism of CLV signaling pathway in the shoot apical meristem.

    Science.gov (United States)

    Kinoshita, Atsuko; Seo, Mitsunori; Kamiya, Yuji; Sawa, Shinichiro

    2015-01-01

    Postembryonic growth and development in higher plants are ultimately reliant on the activity of meristems, where the cells divide frequently to provide source cells for new organs and tissues while in part maintain their pluripotent nature as stem cells. The shoot apical meristem (SAM) is maintained throughout the life of plants and responsible for the development of all areal tissues. In Arabidopsis thaliana, the size of SAM is controlled by a peptide ligand, CLAVATA3 (CLV3). Previously, genetic studies have identified several genes that function downstream of CLV3, many of which, intriguingly, encode receptors. Recently we identified an E3 ubiquitin ligase, PLANT U-BOX 4 (PUB4), as a key regulatory component of root meristem maintenance that functions downstream of an exogenous synthetic CLV3 peptide. Here, we report an additional function of PUB4 in the SAM.

  9. Microbiome in the Apical Root Canal System of Teeth with Post-Treatment Apical Periodontitis

    Science.gov (United States)

    Siqueira, José F.; Antunes, Henrique S.; Rôças, Isabela N.; Rachid, Caio T. C. C.

    2016-01-01

    Introduction Bacteria present in the apical root canal system are directly involved with the pathogenesis of post-treatment apical periodontitis. This study used a next-generation sequencing approach to identify the bacterial taxa occurring in cryopulverized apical root samples from root canal-treated teeth with post-treatment disease. Methods Apical root specimens obtained during periradicular surgery of ten adequately treated teeth with persistent apical periodontitis were cryogenically ground. DNA was extracted from the powder and the microbiome was characterized on the basis of the V4 hypervariable region of the 16S rRNA gene by using paired-end sequencing on Illumina MiSeq device. Results All samples were positive for the presence of bacterial DNA. Bacterial taxa were mapped to 11 phyla and 103 genera composed by 538 distinct operational taxonomic units (OTUs) at 3% of dissimilarity. Over 85% of the sequences belonged to 4 phyla: Proteobacteria, Firmicutes, Fusobacteria and Actinobacteria. In general, these 4 phyla accounted for approximately 80% of the distinct OTUs found in the apical root samples. Proteobacteria was the most abundant phylum in 6/10 samples. Fourteen genera had representatives identified in all cases. Overall, the genera Fusobacterium and Pseudomonas were the most dominant. Enterococcus was found in 4 cases, always in relatively low abundance. Conclusions This study showed a highly complex bacterial community in the apical root canal system of adequately treated teeth with persistent apical periodontitis. This suggests that this disease is characterized by multispecies bacterial communities and has a heterogeneous etiology, because the community composition largely varied from case to case. PMID:27689802

  10. The Smc5-Smc6 complex is required to remove chromosome junctions in meiosis.

    Directory of Open Access Journals (Sweden)

    Sarah Farmer

    Full Text Available Meiosis, a specialized cell division with a single cycle of DNA replication round and two consecutive rounds of nuclear segregation, allows for the exchange of genetic material between parental chromosomes and the formation of haploid gametes. The structural maintenance of chromosome (SMC proteins aid manipulation of chromosome structures inside cells. Eukaryotic SMC complexes include cohesin, condensin and the Smc5-Smc6 complex. Meiotic roles have been discovered for cohesin and condensin. However, although Smc5-Smc6 is known to be required for successful meiotic divisions, the meiotic functions of the complex are not well understood. Here we show that the Smc5-Smc6 complex localizes to specific chromosome regions during meiotic prophase I. We report that meiotic cells lacking Smc5-Smc6 undergo catastrophic meiotic divisions as a consequence of unresolved linkages between chromosomes. Surprisingly, meiotic segregation defects are not rescued by abrogation of Spo11-induced meiotic recombination, indicating that at least some chromosome linkages in smc5-smc6 mutants originate from other cellular processes. These results demonstrate that, as in mitosis, Smc5-Smc6 is required to ensure proper chromosome segregation during meiosis by preventing aberrant recombination intermediates between homologous chromosomes.

  11. Abceso apical agudo

    OpenAIRE

    Jara Ortiz, M.; López, M.; Gómez Viglino, L.; Maydana, N.; Hervit, M.; Bertola, N.

    2015-01-01

    En casos de urgencia, muchas veces debemos poner a prueba distintos elementos de diagnóstico para encontrar la mejor respuesta posible. En este caso se reporta un absceso apical agudo en la zona palatina del sector 1, que, de acuerdo al test de vitalidad pulpar y correcta interpretación radiográfica se localiza la pieza causal N° 1.8.Asistió a la consulta un paciente masculino 30 años de edad, dolor a la masticación, edema y tumefacción, en zona palatina comprendida en piezas 1.5; 1.6; 1.7 y ...

  12. Two cases of apical ballooning syndrome masking apical hypertrophic cardiomyopathy.

    Science.gov (United States)

    Roy, Ranjini Raina; Hakim, Fayaz A; Hurst, R Todd; Simper, David; Appleton, Christopher P

    2014-04-01

    Apical akinesis and dilation in the absence of obstructive coronary artery disease is a typical feature of stress-induced (takotsubo) cardiomyopathy, whereas apical hypertrophy is seen in apical-variant hypertrophic cardiomyopathy. We report the cases of 2 patients who presented with takotsubo cardiomyopathy and were subsequently found to have apical-variant hypertrophic cardiomyopathy, after the apical ballooning from the takotsubo cardiomyopathy had resolved. The first patient, a 43-year-old woman with a history of alcohol abuse, presented with shortness of breath, electrocardiographic and echocardiographic features consistent with takotsubo cardiomyopathy, and no significant coronary artery disease. An echocardiogram 2 weeks later revealed a normal left ventricular ejection fraction and newly apparent apical hypertrophy. The 2nd patient, a 70-year-old woman with pancreatitis, presented with chest pain, apical akinesis, and a left ventricular ejection fraction of 0.39, consistent with takotsubo cardiomyopathy. One month later, her left ventricular ejection fraction was normal; however, hypertrophy of the left ventricular apex was newly noted. To our knowledge, these are the first reported cases in which apical-variant hypertrophic cardiomyopathy was masked by apical ballooning from stress-induced cardiomyopathy.

  13. Experimental and numerical study of a complex cross-junction microchannel

    Science.gov (United States)

    Nowak, Emilia; Simmons, Mark; Kahouadji, Lyes; Craster, Richard; Matar, Omar; Juric, Damir; Chergui, Jalel; Shin, Seungwon

    2016-11-01

    Microfluidic devices occur in various fields such as inkjet printing, DNA chips, lab-on-a-chip technology, micro-propulsion and droplet-based microfluidics. Here, we examine drop and plug formation of immiscible liquids in a cross-shaped microchannel via high-speed imaging, shadowgraphy and PIV that allows interface topology and flow field tracking. We also present comparisons with direct numerical simulations using the new solver, BLUE, for massively parallel simulations of fully three-dimensional multiphase flows in complex solid geometries. EPSRC UK Programme Grant MEMPHIS (EP/K003976/1).

  14. Bacterial interference with host epithelial junctional complexes: Probiotic bacteria vs. A/E lesion-forming Escherichia coli

    Directory of Open Access Journals (Sweden)

    TANIA TOPOUZOVA-HRISTOVA

    2012-01-01

    Full Text Available During colonization, enteropathogenic (EPEC and enterohaemorrhagic (EHEC Escherichia coli are capable to manipulate host cytoskeleton and colonize gut epithelia by a specific mode of attachment known as the attaching and effacing lesion (A/E lesion. While actin rearrangements during A/E lesion formation have been extensively investigated, the possible alterations of other cytoskeletal elements like those comprising the intercellular junctional complexes (JC of polarized cells during infection have only lately attracted attention. The present mini-review addresses the opposite effects of two groups of bacteria, A/E lesion-forming pathogenic E. coli and probiotic bacterial strains, on JC. JC are important in maintaining gut barrier functions. EPEC and EHEC can disrupt JC which as a consequence leads to reduction in the transepitelial electrical resistance (TER and an increase of the permeability to macromolecules. Probiotic bacteria on the other hand stabilize JC thus increasing TER and reducing permeability to macromolecular markers. Probiotic strains can protect JC integrity of polarized cells from the damage caused by EPEC or EHEC. Together with the promise of these results, of concern is the fact that the outcome of the studies can differ dependent on experimental protocols. Studies with living bacteria and different strain combinations have also put forward strain specific effects. Therefore, an important practical item for future studies is the identification of the molecules synthesized by probiotic bacteria that may be active on JC stability.

  15. Effects of radiographic contrast media on the micromorphology of the junctional complex of erythrocytes visualized by immunocytology.

    Science.gov (United States)

    Franke, Ralf-Peter; Krüger, Anne; Scharnweber, Tim; Wenzel, Folker; Jung, Friedrich

    2014-09-12

    Effects of radiographic contrast media (RCM) application were demonstrated in vitro and in vivo where the injection of RCM into the A. axillaris of patients with coronary artery disease was followed by a significant and RCM-dependent decrease of erythrocyte velocity in downstream skin capillaries. Another study in pigs revealed that the deceleration of erythrocytes coincided with a significant reduction of the oxygen partial pressure in the myocardium--supplied by the left coronary artery--after the administration of RCM into this artery. Further reports showed RCM dependent alterations of erythrocytes like echinocyte formation and exocytosis, sequestration of actin or band 3 and the buckling of endothelial cells coinciding with a formation of interendothelial fenestrations leading to areas devoid of endothelial cells. Key to morphological alterations of erythrocytes is the membrane cytoskeleton, which is linked to the band 3 in the erythrocyte membrane via the junctional complex. Fundamental observations regarding the cell biological and biochemical aspects of the structure and function of the cell membrane and the membrane cytoskeleton of erythrocytes have been reported. This review focuses on recent results gained, e.g., by advanced confocal laser scanning microscopy of different double-stained structural elements of the erythrocyte membrane cytoskeleton.

  16. Knock and Drill Technique: A Simple Tips for the Instrumentation in Complex Craniovertebral Junction Anomalies without using Fluoroscopy

    Science.gov (United States)

    Srivastava, Arun; Sardhara, Jayesh; Behari, Sanjay; Pavaman, Sindgikar; Joseph, Jeena; Das, Kuntal; Mehrotra, Anant; Jaiswal, Awadhesh K.; Bhaishora, Kamlesh

    2017-01-01

    Context: Existence of complex variable bony and vertebral artery (VA) anomalies at craniovertebral junction (CVJ) in subset of complex CVJ anomalies demands individualized instrumentation policy and placing screws in each bone requires strategic preoperative planning and intraoperative skills. Aim: To evaluate the clinical accuracy of knock and drill (K and D) technique for the screw placement in complex CVJ anomalies. Settings and Design: Prospective study and operative technical note. Materials and Methods: Totally 36 consecutive patients (16 - pediatrics, 20 - adult patients) of complex CVJ: Complete/partial occipitalized C1 vertebra; at least one hypoplastic (C1/C2) articular mass, rotational component, and variations in the third part of VA were included in this study. Preoperative detail computed tomography (CT) CT CVJ with three-dimensional reconstruction was done for the assessment of CVJ anatomy and facet joint orientation. The accuracy of novel technique was assessed with postoperative CT to evaluate cortical breach in between 5th and 7th postoperative day in all the patients. All patients were underwent clinico-radiological evaluation at 6-month follow-up. Results: Totally 144 screws were placed using K and D technique (pediatric group - 64 screws, adult patients - 80 screws). Total of 12 screws were placed in C1 lateral mass in both age group without any bony cortical breach and complication. Sixteen C2 pedicle screws and 12 C2 pars screw in pediatrics and 18 C2 pedicle screws in adult patients were placed without any bony breach or VA injury. Out of thirty subaxial lateral mass screws in pediatric group, the bony breach was encountered with one screw (3.3%). Total of 38 C2 pars screws was placed in adult group in which bony breach along with VA injury was encounter with 1screw (2.6%). Conclusion: A simple technique of K and D for placing a screw increases the accuracy and spectrum of bony purchase and has the potential to reduce the complication in

  17. Colgajo de reposición apical Apically positioned flap

    Directory of Open Access Journals (Sweden)

    L. Pérez-Salcedo

    2011-08-01

    Full Text Available Se describe la técnica del colgajo de reposición apical desde el primer autor, Nabers en 1954, así como las modificaciones realizadas por Ariaudo y Tyrrel en 1957 y Friedman en 1962. También se presenta un caso clínico donde se describen los diferentes pasos de la cirugía de reposición apical. Por último, se hace una revisión evaluando la eficacia del colgajo de reposición apical en el tratamiento de la periodontitis.This paper describes the technique apically positioned flap since the first author Nabers in 1954 and also the modifications performed by Ariaudo and Tyrrell in 1957 and Friedman in 1962. Also a clinical case is presented where it can be observed the different steps of the apically positioned flap in clinical pictures. Afterwards some papers in which the efficacy of the apically positioned flap in the treatment of periodontitis are evaluated and described.

  18. Extra-anatomic right ventricle to pulmonary artery conduit: the apical-aortic equivalent for complex right ventricular outflow tract reconstruction.

    Science.gov (United States)

    Mori, Makoto; Siddharthan, Ragavan; Kogon, Brian

    2015-03-01

    We describe the case of a 22-year-old with tetralogy of Fallot, who underwent complete repair with ventricular septal defect closure and right ventricle to pulmonary artery conduit placement. She has undergone numerous subsequent conduit changes, each complicated by early stenosis and failure. Unfortunately, serial conduit changes can become increasingly challenging. While extra-anatomic conduits have been described for complex left ventricular outflow tract obstruction, they have not been described for right-sided obstruction. Herein, we present a patient who underwent successful placement of an extra-anatomic valved right ventricle to pulmonary artery conduit in the setting of complex right ventricular outflow tract obstruction.

  19. Lateral junction dynamics lead the way out.

    Science.gov (United States)

    Behrndt, Martin; Heisenberg, Carl-Philipp

    2014-02-01

    Epithelial cell layers need to be tightly regulated to maintain their integrity and correct function. Cell integration into epithelial sheets is now shown to depend on the N-WASP-regulated stabilization of cortical F-actin, which generates distinct patterns of apical-lateral contractility at E-cadherin-based cell-cell junctions.

  20. The Drosophila larval neuromuscular junction as a model for scaffold complexes at glutamatergic synapses: benefits and limitations.

    Science.gov (United States)

    Thomas, Ulrich; Kobler, Oliver; Gundelfinger, Eckart D

    2010-09-01

    Based on unbeatable genetic accessibility and relative simplicity, the Drosophila larval neuromuscular junction has become a widely used model system for studying functional and structural aspects of excitatory glutamatergic synapses. Membrane-associated guanylate kinase-like proteins (MAGUKs) are first-order scaffolding molecules enriched at many cellular junctions, including synapses, where they coordinate multiple binding partners, including cell adhesion molecules and ion channels. The enrichment of the prototypic MAGUK Discs-Large at larval NMJs apparently parallels the high abundance of its homologs at excitatory synapses in the mammalian central nervous system. Here, the authors review selected aspects of the long-standing work on Dlg at fly neuromuscular junctions, thereby scrutinizing its subcellular localization, function, and regulation with regard to corresponding aspects of MAGUKs in vertebrate neurons.

  1. The stardust family protein MPP7 forms a tripartite complex with LIN7 and DLG1 that regulates the stability and localization of DLG1 to cell junctions.

    Science.gov (United States)

    Bohl, Joanna; Brimer, Nicole; Lyons, Charles; Vande Pol, Scott B

    2007-03-30

    MPP7, a previously uncharacterized member of the p55 Stardust family of membrane-associated guanylate kinase (MAGUK) proteins, was found in a tripartite complex with DLG1 and LIN7A or LIN7C. MPP7 dimerizes with all three LIN7 family members (LIN7A, -B, and -C) through interaction of the single L27 domain of LIN7 with the carboxyl-terminal L27 domain of MPP7, thereby stabilizing both proteins. The dimer of MPP7 with LIN7A or LIN7C associates with DLG1 through an interaction requiring the amino-terminal L27 domain of MPP7. The amino-terminal L27 domain of MPP7 is not sufficient for interaction with DLG1 but interacts efficiently only if MPP7 is in a complex with LIN7A or -C. Thus the specificity of interaction of DLG1 with the LIN7-MPP7 complex is determined by L27 interactions with both MPP7 and LIN7. The tripartite complex forms in a ratio of 1:1:1 and localizes to epithelial adherens junctions in a manner dependent upon MPP7. Expression of MPP7 stabilizes DLG1 in an insoluble compartment. Expression of MPP7 deleted of the PDZ or Src homology 3 domain redistributes MPP7, DLG1, and LIN7 out of adherens junctions and into the soluble cytoplasmic fraction without changing the localization of E-cadherin. Thus, the stability and localization of DLG1 to cell-cell junctions are complex functions determined by the expression and association of particular Stardust family members together with particular LIN7 family members.

  2. Porcine lactoferrin-derived peptide LFP-20 protects intestinal barrier by maintaining tight junction complex and modulating inflammatory response.

    Science.gov (United States)

    Zong, Xin; Hu, Wangyang; Song, Deguang; Li, Zhi; Du, Huahua; Lu, Zeqing; Wang, Yizhen

    2016-03-15

    LFP-20, a 20-amino acid antimicrobial peptide in the N terminus of porcine lactoferrin, has antimicrobial and immunomodulatory activities. This study assessed the protective effects of LFP-20 on LPS-induced intestinal damage in a LPS-induced mouse model and in vitro, using intestinal porcine epithelial cell line 1 (IPEC-1) cells. LFP-20 prevented LPS-induced impairment in colon epithelium tissues, infiltration of macrophages or leukocytes, histological evidence of inflammation and increased levels of TNF-a, IL-6 and IFN-γ. LFP-20 increased the expression of zonula occludens-1, occludin and claudin-1 and reduced permeability as well as apoptosis of the colon in LPS-treated mice. In IPEC-1 cells, LFP-20 increased transepithelial electrical resistance and tight junction expression. Moreover, we found LFP-20 decreased the MyD88 and AKT levels to affect the NF-κB signaling pathway, to modulate inflammation response and tight junction networks in the processing of LPS stimulation. In summary, LFP-20 prevents the inflammatory response and disruption of tight junction structure induced by LPS, suggesting the potential use of LFP-20 as a prophylactic agent to protect intestinal barrier function.

  3. Apical constriction: themes and variations on a cellular mechanism driving morphogenesis.

    Science.gov (United States)

    Martin, Adam C; Goldstein, Bob

    2014-05-01

    Apical constriction is a cell shape change that promotes tissue remodeling in a variety of homeostatic and developmental contexts, including gastrulation in many organisms and neural tube formation in vertebrates. In recent years, progress has been made towards understanding how the distinct cell biological processes that together drive apical constriction are coordinated. These processes include the contraction of actin-myosin networks, which generates force, and the attachment of actin networks to cell-cell junctions, which allows forces to be transmitted between cells. Different cell types regulate contractility and adhesion in unique ways, resulting in apical constriction with varying dynamics and subcellular organizations, as well as a variety of resulting tissue shape changes. Understanding both the common themes and the variations in apical constriction mechanisms promises to provide insight into the mechanics that underlie tissue morphogenesis.

  4. Drosophila PATJ supports adherens junction stability by modulating Myosin light chain activity

    National Research Council Canada - National Science Library

    Sen, Arnab; Nagy-Zsvér-Vadas, Zsanett; Krahn, Michael P

    2012-01-01

    ... (Pals1-associated tight junction protein) was not per se crucial for the maintenance of apical-basal polarity in Drosophila melanogaster epithelial cells but rather regulated Myosin localization and phosphorylation...

  5. Paracellin-1, a renal tight junction protein required for paracellular Mg2+ resorption

    NARCIS (Netherlands)

    Simon, DB; Lu, Y; Choate, KA; Velazquez, H; Al-Sabban, E; Praga, M; Casari, C; Bettinelli, A; Colussi, C; Rodriguez-Soriano, J; McCredie, D; Milford, D; Sanjad, S; Lifton, RP

    1999-01-01

    Epithelia permit selective and regulated flux from apical to basolateral surfaces by transcellular passage through cells or paracellular flux between cells. Tight junctions constitute the barrier to paracellular conductance; however, Little is known about the specific molecules that mediate paracell

  6. The Exon Junction Complex Controls the Efficient and Faithful Splicing of a Subset of Transcripts Involved in Mitotic Cell-Cycle Progression

    Directory of Open Access Journals (Sweden)

    Kazuhiro Fukumura

    2016-08-01

    Full Text Available The exon junction complex (EJC that is deposited onto spliced mRNAs upstream of exon–exon junctions plays important roles in multiple post-splicing gene expression events, such as mRNA export, surveillance, localization, and translation. However, a direct role for the human EJC in pre-mRNA splicing has not been fully understood. Using HeLa cells, we depleted one of the EJC core components, Y14, and the resulting transcriptome was analyzed by deep sequencing (RNA-Seq and confirmed by RT–PCR. We found that Y14 is required for efficient and faithful splicing of a group of transcripts that is enriched in short intron-containing genes involved in mitotic cell-cycle progression. Tethering of EJC core components (Y14, eIF4AIII or MAGOH to a model reporter pre-mRNA harboring a short intron showed that these core components are prerequisites for the splicing activation. Taken together, we conclude that the EJC core assembled on pre-mRNA is critical for efficient and faithful splicing of a specific subset of short introns in mitotic cell cycle-related genes.

  7. Exon Junction Complexes Show a Distributional Bias toward Alternatively Spliced mRNAs and against mRNAs Coding for Ribosomal Proteins

    Directory of Open Access Journals (Sweden)

    Christian Hauer

    2016-08-01

    Full Text Available The exon junction complex (EJC connects spliced mRNAs to posttranscriptional processes including RNA localization, transport, and regulated degradation. Here, we provide a comprehensive analysis of bona fide EJC binding sites across the transcriptome including all four RNA binding EJC components eIF4A3, BTZ, UPF3B, and RNPS1. Integration of these data sets permits definition of high-confidence EJC deposition sites as well as assessment of whether EJC heterogeneity drives alternative nonsense-mediated mRNA decay pathways. Notably, BTZ (MLN51 or CASC3 emerges as the EJC subunit that is almost exclusively bound to sites 20–24 nucleotides upstream of exon-exon junctions, hence defining EJC positions. By contrast, eIF4A3, UPF3B, and RNPS1 display additional RNA binding sites suggesting accompanying non-EJC functions. Finally, our data show that EJCs are largely distributed across spliced RNAs in an orthodox fashion, with two notable exceptions: an EJC deposition bias in favor of alternatively spliced transcripts and against the mRNAs that encode ribosomal proteins.

  8. Emerging relationship between CFTR, actin and tight junction organization in cystic fibrosis airway epithelium.

    Science.gov (United States)

    Castellani, Stefano; Favia, Maria; Guerra, Lorenzo; Carbone, Annalucia; Abbattiscianni, Anna Claudia; Di Gioia, Sante; Casavola, Valeria; Conese, Massimo

    2017-05-01

    Cystic fibrosis (CF), one of the most common genetic disorders affecting primarily Caucasians, is due to mutations in the CF Transmembrane Conductance Regulator (CFTR) gene, encoding for a chloride channel also acting as regulator of other transmembrane proteins. In healthy subjects, CFTR is maintained in its correct apical plasma membrane location via the formation of a multiprotein complex in which scaffold proteins (such as NHERF1) and signaling molecules (such as cAMP and protein kinases) guarantee its correct functioning. In CF, a disorganized and dysfunctional airway epithelium brings an altered flux of ions and water into the lumen of bronchioles, consequent bacterial infections and an enormous influx of inflammatory cells (mainly polymorphonuclear neutrophils) into the airway lumen. Recent evidence in healthy airway cells supports the notion that CFTR protein/function is strictly correlated with the actin cytoskeleton and tight junctions status. In CF cells, the most frequent CFTR gene mutation, F508del, has been shown to be associated with a disorganized actin cytoskeleton and altered tight junction permeability. Thus, the correct localization of CFTR on the apical plasma membrane domain through the formation of the scaffolding and signaling complex is likely fundamental to determine a physiological airway epithelium. The correction of CFTR mutations by either gene or drug therapies, as well as by stem cell-based interventions, can determine the resumption of a physiological organization of actin stress fibers and TJ structure and barrier function, further indicating the close interrelationship among these processes.

  9. Prolactin/Jak2 directs apical/basal polarization and luminal linage maturation of mammary epithelial cells through regulation of the Erk1/2 pathway

    Directory of Open Access Journals (Sweden)

    Fengming Liu

    2015-09-01

    Full Text Available Tissue development/remodeling requires modulations in both cellular architecture and phenotype. Aberration in these processes leads to tumorigenesis. During the pregnancy/lactation cycle the mammary epithelial cells undergo complex morphological and phenotypic programs resulting in the acquisition of apical/basal (A/B polarization and cellular maturation necessary for proper lactation. Still the hormonal regulations and cellular mechanisms controlling these events are not entirely elucidated. Here we show that prolactin (PRL/Jak2 pathway in mammary epithelial cells uniquely signals to establish A/B polarity as determined by the apical localization of the tight junction protein zona occludens 1 (ZO-1 and the basal/lateral localization of E-cadherin, and the apical trafficking of lipid droplets. As well, our results indicate that this pathway regulates mammary stem cell hierarchy by inducing the differentiation of luminal progenitor (EpCAMhi/CD49fhi cells to mature luminal (EpCAMhi/CD49flow cells. Moreover, our data indicate that PRL/Jak2 coordinates both of these cellular events through limiting the mitogen activated protein kinase (Erk1/2 pathway. Together our findings define a novel unifying mechanism coupling mammary epithelial cell A/B polarization and terminal differentiation.

  10. Function of root apical meristem

    OpenAIRE

    Benešová, Šárka

    2013-01-01

    A root apical meristem is the only source of cells for all tissues in the root. The root growth relies on its function. Regulation of a cell division frequency and cell differentiation affects organization and function of the differentiated tissues and the proper meristem function. If the cell differentiation overbalances the cell proliferation, the meristem exhaustion occurs and the root growth irreversibly terminates. This thesis describes existing knowledge about regulation of the primary ...

  11. GEN1/Yen1 and the SLX4 complex: solutions to the problem of Holliday junction resolution

    Science.gov (United States)

    Svendsen, Jennifer M.; Harper, J. Wade

    2010-01-01

    Chromosomal double-strand breaks (DSBs) are considered to be among the most deleterious DNA lesions found in eukaryotic cells due to their propensity to promote genome instability. DSBs occur as a result of exogenous or endogenous DNA damage, and also occur during meiotic recombination. DSBs are often repaired through a process called homologous recombination (HR), which employs the sister chromatid in mitotic cells or the homologous chromosome in meiotic cells, as a template for repair. HR frequently involves the formation and resolution of four-way DNA structures referred to as the Holliday junction (HJ). Despite extensive study, the machinery and mechanisms used to process these structures in eukaryotes have remained poorly understood. Recent work has identified XPG and UvrC/GIY domain-containing structure-specific endonucleases that can symmetrically cleave HJs in vitro in a manner that allows for religation without additional processing, properties that are reminiscent of the classical RuvC HJ resolvase in bacteria. Genetic studies reveal potential roles for these HJ resolvases in repair after DNA damage and during meiosis. The stage is now set for a more comprehensive understanding of the specific roles these enzymes play in the response of cells to DSBs, collapsed replication forks, telomere dysfunction, and meiotic recombination. PMID:20203129

  12. An asymmetric A-B-A' metallo-supramolecular triblock copolymer linked by Ni(2+)-bis-terpyridine complexes at one junction.

    Science.gov (United States)

    Li, Haixia; Wei, Wei; Xiong, Huiming

    2016-02-01

    A metallo-supramolecular triblock copolymer polystyrene-b-polyisoprene-[Ni(2+)]-polystyrene (SI-[Ni(2+)]-S') has been efficiently prepared using a one-pot, two-step procedure, where the blocks are held by bis-terpyridine complexes at the junction of SI-S'. This specific metallo-supramolecular chemistry is demonstrated to be a robust approach to potentially broaden the diversity of block copolymers. The location of the metal-ligand complexes has a profound influence on the phase separation of the triblock copolymer in the bulk, which results in a distinctive phase segregation between the end blocks and leads to an unexpected asymmetry of the triblock copolymer. The metal-ligand complexes are found to be preferentially located on the adjacent spherical domain and form a core-shell structure. The resulting multiphase material exhibits distinct elastomeric properties with significant toughness and creep recovery behavior. This type of triblock copolymer is anticipated to be a novel class of hybrid thermo-plastic elastomeric material with wide tunability and functionality.

  13. Disruption of the Cdc42/Par6/aPKC or Dlg/Scrib/Lgl Polarity Complex Promotes Epithelial Proliferation via Overlapping Mechanisms.

    Science.gov (United States)

    Schimizzi, Gregory V; Maher, Meghan T; Loza, Andrew J; Longmore, Gregory D

    2016-01-01

    The establishment and maintenance of apical-basal polarity is a defining characteristic and essential feature of functioning epithelia. Apical-basal polarity (ABP) proteins are also tumor suppressors that are targeted for disruption by oncogenic viruses and are commonly mutated in human carcinomas. Disruption of these ABP proteins is an early event in cancer development that results in increased proliferation and epithelial disorganization through means not fully characterized. Using the proliferating Drosophila melanogaster wing disc epithelium, we demonstrate that disruption of the junctional vs. basal polarity complexes results in increased epithelial proliferation via distinct downstream signaling pathways. Disruption of the basal polarity complex results in JNK-dependent proliferation, while disruption of the junctional complex primarily results in p38-dependent proliferation. Surprisingly, the Rho-Rok-Myosin contractility apparatus appears to play opposite roles in the regulation of the proliferative phenotype based on which polarity complex is disrupted. In contrast, non-autonomous Tumor Necrosis Factor (TNF) signaling appears to suppress the proliferation that results from apical-basal polarity disruption, regardless of which complex is disrupted. Finally we demonstrate that disruption of the junctional polarity complex activates JNK via the Rho-Rok-Myosin contractility apparatus independent of the cortical actin regulator, Moesin.

  14. 'Special K' and a Loss of Cell-To-Cell Adhesion in Proximal Tubule-Derived Epithelial Cells: Modulation of the Adherens Junction Complex by Ketamine

    Science.gov (United States)

    Hills, Claire E.; Jin, Tianrong; Siamantouras, Eleftherios; Liu, Issac K-K; Jefferson, Kieran P.; Squires, Paul E.

    2013-01-01

    Ketamine, a mild hallucinogenic class C drug, is the fastest growing ‘party drug’ used by 16–24 year olds in the UK. As the recreational use of Ketamine increases we are beginning to see the signs of major renal and bladder complications. To date however, we know nothing of a role for Ketamine in modulating both structure and function of the human renal proximal tubule. In the current study we have used an established model cell line for human epithelial cells of the proximal tubule (HK2) to demonstrate that Ketamine evokes early changes in expression of proteins central to the adherens junction complex. Furthermore we use AFM single-cell force spectroscopy to assess if these changes functionally uncouple cells of the proximal tubule ahead of any overt loss in epithelial cell function. Our data suggests that Ketamine (24–48 hrs) produces gross changes in cell morphology and cytoskeletal architecture towards a fibrotic phenotype. These physical changes matched the concentration-dependent (0.1–1 mg/mL) cytotoxic effect of Ketamine and reflect a loss in expression of the key adherens junction proteins epithelial (E)- and neural (N)-cadherin and β-catenin. Down-regulation of protein expression does not involve the pro-fibrotic cytokine TGFβ, nor is it regulated by the usual increase in expression of Slug or Snail, the transcriptional regulators for E-cadherin. However, the loss in E-cadherin can be partially rescued pharmacologically by blocking p38 MAPK using SB203580. These data provide compelling evidence that Ketamine alters epithelial cell-to-cell adhesion and cell-coupling in the proximal kidney via a non-classical pro-fibrotic mechanism and the data provides the first indication that this illicit substance can have major implications on renal function. Understanding Ketamine-induced renal pathology may identify targets for future therapeutic intervention. PMID:24009666

  15. Glucocorticoids upregulates transepithelial electrical resistance and expression of tight junction-related protein in human trabecular meshwork cells

    Institute of Scientific and Technical Information of China (English)

    ZHUO Ye-hong; HUANG Ya-lin; WEI Yan-tao; LING Yun-lan; LIN Ming-kai; GE Jian

    2005-01-01

    @@ The trabecular meshwork is located at the anterior chamber angle, and is the main route for the outflow of aqueous humor. It is composed of perforated sheets of collagen and elastic tissue covered by trabecular meshwork (TM) cells, forming a filter with decreasing pore size as the canal of Schlemm is approached. TM cells have some endothelial properties, such as the presence of intercellular junctional complexes, particularly tight junctions (TJs). TJs form paracellular seals between adjacent cells and act as fences that segregate protein (and partially lipid) components of the apical and basolateral plasma membrane domains. Under the electron microscope, TJs appear as a series of discrete contacts between the lateral membranes of adjacent cells.

  16. Nerve signaling regulates basal keratinocyte proliferation in the blastema apical epithelial cap in the axolotl (Ambystoma mexicanum).

    Science.gov (United States)

    Satoh, Akira; Bryant, Susan V; Gardiner, David M

    2012-06-15

    The ability of adult vertebrates to repair tissue damage is widespread and impressive; however, the ability to regenerate structurally complex organs such as the limb is limited largely to the salamanders. The fact that most of the tissues of the limb can regenerate has led investigators to question and identify the barriers to organ regeneration. From studies in the salamander, it is known that one of the earliest steps required for successful regeneration involves signaling between nerves and the wound epithelium/apical epithelial cap (AEC). In this study we confirm an earlier report that the keratinocytes of the AEC acquire their function coincident with exiting the cell cycle. We have discovered that this unique, coordinated behavior is regulated by nerve signaling and is associated with the presence of gap junctions between the basal keratinocytes of the AEC. Disruption of nerve signaling results in a loss of gap junction protein, the reentry of the cells into the cell cycle, and regenerative failure. Finally, coordinated exit from the cell cycle appears to be a conserved behavior of populations of cells that function as signaling centers during both development and regeneration.

  17. Agglutinating secretory IgA preserves intestinal epithelial cell integrity during apical infection by Shigella flexneri.

    Science.gov (United States)

    Mathias, Amandine; Longet, Stéphanie; Corthésy, Blaise

    2013-08-01

    Shigella flexneri, by invading intestinal epithelial cells (IECs) and inducing inflammatory responses of the colonic mucosa, causes bacillary dysentery. Although M cells overlying Peyer's patches are commonly considered the primary site of entry of S. flexneri, indirect evidence suggests that bacteria can also use IECs as a portal of entry to the lamina propria. Passive delivery of secretory IgA (SIgA), the major immunoglobulin secreted at mucosal surfaces, has been shown to protect rabbits from experimental shigellosis, but no information exists as to its molecular role in maintaining luminal epithelial integrity. We have established that the interaction of virulent S. flexneri with the apical pole of a model intestinal epithelium consisting of polarized Caco-2 cell monolayers resulted in the progressive disruption of the tight junction network and actin depolymerization, eventually resulting in cell death. The lipopolysaccharide (LPS)-specific agglutinating SIgAC5 monoclonal antibody (MAb), but not monomeric IgAC5 or IgGC20 MAbs of the same specificity, achieved protective functions through combined mechanisms, including limitation of the interaction between S. flexneri and epithelial cells, maintenance of the tight junction seal, preservation of the cell morphology, reduction of NF-κB nuclear translocation, and inhibition of proinflammatory mediator secretion. Our results add to the understanding of the function of SIgA-mediated immune exclusion by identifying a mode of action whereby the formation of immune complexes translates into maintenance of the integrity of epithelial cells lining the mucosa. This novel mechanism of protection mediated by SIgA is important to extend the arsenal of effective strategies to fight against S. flexneri mucosal invasion.

  18. JAM-C is an apical surface marker for neural stem cells.

    Science.gov (United States)

    Stelzer, Sandra; Worlitzer, Maik M A; Bahnassawy, Lamia'a; Hemmer, Kathrin; Rugani, Kirité; Werthschulte, Inga; Schön, Anna-Lena; Brinkmann, Benjamin F; Bunk, Eva C; Palm, Thomas; Ebnet, Klaus; Schwamborn, Jens C

    2012-03-20

    Junctional adhesion molecule-C (JAM-C) is an adhesive cell surface protein expressed in various cell types. JAM-C localizes to the apically localized tight junctions (TJs) between contacting endothelial and epithelial cells, where it contributes to cell-cell adhesions. Just as those epithelial cells, also neural stem cells are highly polarized along their apical-basal axis. The defining feature of all stem cells, including neural stem cells (NSCs) is their ability to self renew. This self-renewal depends on the tight control of symmetric and asymmetric cell divisions. In NSCs, the decision whether a division is symmetric or asymmetric largely depends on the distribution of the apical membrane and cell fate determinants on the basal pole of the cell. In this study we demonstrate that JAM-C is expressed on neural progenitor cells and neural stem cells in the embryonic as well as the adult mouse brain. Furthermore, we demonstrate that in vivo JAM-C shows enrichment at the apical surface and therefore is asymmetrically distributed during cell divisions. These results define JAM-C as a novel surface marker for neural stem cells.

  19. Magnesium Lowers the Incidence of Postoperative Junctional Ectopic Tachycardia in Congenital Heart Surgical Patients: Is There a Relationship to Surgical Procedure Complexity?

    Science.gov (United States)

    He, Dingchao; Sznycer-Taub, Nathaniel; Cheng, Yao; McCarter, Robert; Jonas, Richard A; Hanumanthaiah, Sridhar; Moak, Jeffrey P

    2015-08-01

    Magnesium sulfate was given to pediatric cardiac surgical patients during cardiopulmonary bypass period in an attempt to reduce the occurrence of postoperative junctional ectopic tachycardia (PO JET). We reviewed our data to evaluate the effect of magnesium on the occurrence of JET and assess a possible relationship between PO JET and procedure complexity. A total of 1088 congenital heart surgeries (CHS), performed from 2005 to 2010, were reviewed. A total of 750 cases did not receive magnesium, and 338 cases received magnesium (25 mg/kg). All procedures were classified according to Aristotle score from 1 to 4. Overall, there was a statistically significant decrease in PO JET occurrence between the two groups regardless of the Aristotle score, 15.3 % (115/750) in non-magnesium group versus 7.1 % (24/338) in magnesium group, P < 0.001. In the absence of magnesium, the risk of JET increased with increasing Aristotle score, P = 0.01. Following magnesium administration and controlling for body weight, surgical and aortic cross-clamp times in the analyses, reduction in adjusted risk of JET was significantly greater with increasing Aristotle level of complexity (JET in non-magnesium vs. magnesium group, Aristotle level 1: 9.8 vs. 14.3 %, level 4: 11.5 vs. 3.2 %; odds ratio 0.54, 95 % CI 0.31-0.94, P = 0.028). Our data confirmed that intra-operative usage of magnesium reduced the occurrence of PO JET in a larger number and more diverse group of CHS patients than has previously been reported. Further, our data suggest that magnesium's effect on PO JET occurrence seemed more effective in CHS with higher levels of Aristotle complexity.

  20. The EhCPADH112 complex of Entamoeba histolytica interacts with tight junction proteins occludin and claudin-1 to produce epithelial damage.

    Directory of Open Access Journals (Sweden)

    Abigail Betanzos

    Full Text Available Entamoeba histolytica, the protozoan responsible for human amoebiasis, causes between 30,000 and 100,000 deaths per year worldwide. Amoebiasis is characterized by intestinal epithelial damage provoking severe diarrhea. However, the molecular mechanisms by which this protozoan causes epithelial damage are poorly understood. Here, we studied the initial molecular interactions between the E. histolytica EhCPADH112 virulence complex and epithelial MDCK and Caco-2 cells. By confocal microscopy, we discovered that after contact with trophozoites or trophozoite extracts (TE, EhCPADH112 and proteins forming this complex (EhCP112 and EhADH112 co-localize with occludin and claudin-1 at tight junctions (TJ. Immunoprecipitation assays revealed interaction between EhCPADH112 and occludin, claudin-1, ZO-1 and ZO-2. Overlay assays confirmed an interaction of EhCP112 and EhADH112 with occludin and claudin-1, whereas only EhADH112 interacted also with ZO-2. We observed degradation of all mentioned TJ proteins after incubation with TE. Importantly, inhibiting proteolytic activity or blocking the complex with a specific antibody not only prevented TJ protein degradation but also epithelial barrier disruption. Furthermore, we discovered that TE treatment induces autophagy and apoptosis in MDCK cells that could contribute to the observed barrier disruption. Our results suggest a model in which epithelial damage caused by E. histolytica is initiated by the interaction of EhCP112 and EhADH112 with TJ proteins followed by their degradation. Disruption of TJs then induces increased paracellular permeability, thus facilitating the entry of more proteases and other parasite molecules leading eventually to tissue destruction.

  1. Export of a Toxoplasma gondii rhoptry neck protein complex at the host cell membrane to form the moving junction during invasion.

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    Sébastien Besteiro

    2009-02-01

    Full Text Available One of the most conserved features of the invasion process in Apicomplexa parasites is the formation of a moving junction (MJ between the apex of the parasite and the host cell membrane that moves along the parasite and serves as support to propel it inside the host cell. The MJ was, up to a recent period, completely unknown at the molecular level. Recently, proteins originated from two distinct post-Golgi specialised secretory organelles, the micronemes (for AMA1 and the neck of the rhoptries (for RON2/RON4/RON5 proteins, have been shown to form a complex. AMA1 and RON4 in particular, have been localised to the MJ during invasion. Using biochemical approaches, we have identified RON8 as an additional member of the complex. We also demonstrated that all RON proteins are present at the MJ during invasion. Using metabolic labelling and immunoprecipitation, we showed that RON2 and AMA1 were able to interact in the absence of the other members. We also discovered that all MJ proteins are subjected to proteolytic maturation during trafficking to their respective organelles and that they could associate as non-mature forms in vitro. Finally, whereas AMA1 has previously been shown to be inserted into the parasite membrane upon secretion, we demonstrated, using differential permeabilization and loading of RON-specific antibodies into the host cell, that the RON complex is targeted to the host cell membrane, where RON4/5/8 remain associated with the cytoplasmic face. Globally, these results point toward a model of MJ organization where the parasite would be secreting and inserting interacting components on either side of the MJ, both at the host and at its own plasma membranes.

  2. Selective permeability of gap junction channels.

    Science.gov (United States)

    Goldberg, Gary S; Valiunas, Virginijus; Brink, Peter R

    2004-03-23

    Gap junctions mediate the transfer of small cytoplasmic molecules between adjacent cells. A family of gap junction proteins exist that form channels with unique properties, and differ in their ability to mediate the transfer of specific molecules. Mutations in a number of individual gap junction proteins, called connexins, cause specific human diseases. Therefore, it is important to understand how gap junctions selectively move molecules between cells. Rules that dictate the ability of a molecule to travel through gap junction channels are complex. In addition to molecular weight and size, the ability of a solute to transverse these channels depends on its net charge, shape, and interactions with specific connexins that constitute gap junctions in particular cells. This review presents some data and interpretations pertaining to mechanisms that govern the differential transfer of signals through gap junction channels.

  3. Phospho-regulated Drosophila adducin is a determinant of synaptic plasticity in a complex with Dlg and PIP2 at the larval neuromuscular junction

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    Simon Ji Hau Wang

    2014-11-01

    Full Text Available Adducin is a ubiquitously expressed actin- and spectrin-binding protein involved in cytoskeleton organization, and is regulated through phosphorylation of the myristoylated alanine-rich C-terminal kinase (MARCKS-homology domain by protein kinase C (PKC. We have previously shown that the Drosophila adducin, Hu-li tai shao (Hts, plays a role in larval neuromuscular junction (NMJ growth. Here, we find that the predominant isoforms of Hts at the NMJ contain the MARCKS-homology domain, which is important for interactions with Discs large (Dlg and phosphatidylinositol 4,5-bisphosphate (PIP2. Through the use of Proximity Ligation Assay (PLA, we show that the adducin-like Hts isoforms are in complexes with Dlg and PIP2 at the NMJ. We provide evidence that Hts promotes the phosphorylation and delocalization of Dlg at the NMJ through regulation of the transcript distribution of the PAR-1 and CaMKII kinases in the muscle. We also show that Hts interactions with Dlg and PIP2 are impeded through phosphorylation of the MARCKS-homology domain. These results are further evidence that Hts is a signaling-responsive regulator of synaptic plasticity in Drosophila.

  4. A Point Mutation in the Exon Junction Complex Factor Y14 Disrupts Its Function in mRNA Cap Binding and Translation Enhancement.

    Science.gov (United States)

    Chuang, Tzu-Wei; Lee, Kuo-Ming; Lou, Yuan-Chao; Lu, Chia-Chen; Tarn, Woan-Yuh

    2016-04-15

    Eukaryotic mRNA biogenesis involves a series of interconnected steps mediated by RNA-binding proteins. The exon junction complex core protein Y14 is required for nonsense-mediated mRNA decay (NMD) and promotes translation. Moreover, Y14 binds the cap structure of mRNAs and inhibits the activity of the decapping enzyme Dcp2. In this report, we show that an evolutionarily conserved tryptophan residue (Trp-73) of Y14 is critical for its binding to the mRNA cap structure. A Trp-73 mutant (W73V) bound weakly to mRNAs and failed to protect them from degradation. However, this mutant could still interact with the NMD and mRNA degradation factors and retained partial NMD activity. In addition, we found that the W73V mutant could not interact with translation initiation factors. Overexpression of W73V suppressed reporter mRNA translation in vitro and in vivo and reduced the level of a set of nascent proteins. These results reveal a residue of Y14 that confers cap-binding activity and is essential for Y14-mediated enhancement of translation. Finally, we demonstrated that Y14 may selectively and differentially modulate protein biosynthesis.

  5. Distribution of linear growth rates in different directions in root apical meristems

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    Jerzy Nakielski

    2014-01-01

    Full Text Available Growth of apical meristems in plants may be well described by the growth tensor method. Hejnowicz (Envir. Exp. Bot. 1989, 29 determined growth tensors for roots: one with a minimum and the other with a maximum of the relative elemental growth rate in volume and used them for the description of two types of apices: one with an apical cell and merophytes (I, and the other with files of cells converging towards a quiescent centre, CQ (II. In the present paper the same cases are considered from the point of view of a spatial and directional variation of the relative elemental rate of growth in length, RERG1. Maps of the RERG1 in two planes: axial and tangential, the latter determined by periclinal-longitudinal (PL and periclinal-tangential (PT principal growth directions, are shown. In an apical part of apex i where there is maximum volumetric growth, there also occurs a maximum of RERG1 for all directions. In regions other than this RERG1 decreases although RERG1 in the PL direction predominates everywhere. In apex II RERG1 for all directions has a minimum in CQ and becomes increasingly larger with increasing distance from it - the maximum is in the PL direction in the cylindrical part of the apex. In peripheral parts of both apices, in the place of the root/cap junction, RERG, in the anticlinal direction is significantly small.

  6. Transcriptional mechanisms coordinating tight junction assembly during epithelial differentiation.

    Science.gov (United States)

    Boivin, Felix J; Schmidt-Ott, Kai M

    2017-06-01

    Epithelial tissues form a selective barrier via direct cell-cell interactions to separate and establish concentration gradients between the different compartments of the body. Proper function and formation of this barrier rely on the establishment of distinct intercellular junction complexes. These complexes include tight junctions, adherens junctions, desmosomes, and gap junctions. The tight junction is by far the most diverse junctional complex in the epithelial barrier. Its composition varies greatly across different epithelial tissues to confer various barrier properties. Thus, epithelial cells rely on tightly regulated transcriptional mechanisms to ensure proper formation of the epithelial barrier and to achieve tight junction diversity. Here, we review different transcriptional mechanisms utilized during embryogenesis and disease development to promote tight junction assembly and maintenance of intercellular barrier integrity. We focus particularly on the Grainyhead-like transcription factors and ligand-activated nuclear hormone receptors, two central families of proteins in epithelialization. © 2017 New York Academy of Sciences.

  7. Auxin at the Shoot Apical Meristem

    Science.gov (United States)

    Vernoux, Teva; Besnard, Fabrice; Traas, Jan

    2010-01-01

    Plants continuously generate new tissues and organs through the activity of populations of undifferentiated stem cells, called meristems. Here, we discuss the so-called shoot apical meristem (SAM), which generates all the aerial parts of the plant. It has been known for many years that auxin plays a central role in the functioning of this meristem. Auxin is not homogeneously distributed at the SAM and it is thought that this distribution is interpreted in terms of differential gene expression and patterned growth. In this context, auxin transporters of the PIN and AUX families, creating auxin maxima and minima, are crucial regulators. However, auxin transport is not the only factor involved. Auxin biosynthesis genes also show specific, patterned activities, and local auxin synthesis appears to be essential for meristem function as well. In addition, auxin perception and signal transduction defining the competence of cells to react to auxin, add further complexity to the issue. To unravel this intricate signaling network at the SAM, systems biology approaches, involving not only molecular genetics but also live imaging and computational modeling, have become increasingly important. PMID:20452945

  8. Models for the Binary Complex of Bacteriophage T4 Gp59 Helicase Loading Protein. GP32 Single-Stranded DNA-Binding Protein and Ternary Complex with Pseudo-Y Junction DNA

    Energy Technology Data Exchange (ETDEWEB)

    Hinerman, Jennifer M. [Univ. of Toledo, OH (United States); Dignam, J. David [Univ. of Toledo, OH (United States); Mueser, Timothy C. [Univ. of Toledo, OH (United States)

    2012-04-05

    The bacteriophage T4 gp59 helicase assembly protein (gp59) is required for loading of gp41 replicative helicase onto DNA protected by gp32 single-stranded DNA-binding protein. The gp59 protein recognizes branched DNA structures found at replication and recombination sites. Binding of gp32 protein (full-length and deletion constructs) to gp59 protein measured by isothermal titration calorimetry demonstrates that the gp32 protein C-terminal A-domain is essential for protein-protein interaction in the absence of DNA. Sedimentation velocity experiments with gp59 protein and gp32ΔB protein (an N-terminal B-domain deletion) show that these proteins are monomers but form a 1:1 complex with a dissociation constant comparable with that determined by isothermal titration calorimetry. Small angle x-ray scattering (SAXS) studies indicate that the gp59 protein is a prolate monomer, consistent with the crystal structure and hydrodynamic properties determined from sedimentation velocity experiments. SAXS experiments also demonstrate that gp32ΔB protein is a prolate monomer with an elongated A-domain protruding from the core. Moreover, fitting structures of gp59 protein and the gp32 core into the SAXS-derived molecular envelope supports a model for the gp59 protein-gp32ΔB protein complex. Our earlier work demonstrated that gp59 protein attracts full-length gp32 protein to pseudo-Y junctions. A model of the gp59 protein-DNA complex, modified to accommodate new SAXS data for the binary complex together with mutational analysis of gp59 protein, is presented in the accompanying article (Dolezal, D., Jones, C. E., Lai, X., Brister, J. R., Mueser, T. C., Nossal, N. G., and Hinton, D. M. (2012) J. Biol. Chem. 287, 18596–18607).

  9. Helicobacter pylori dwelling on the apical surface of gastrointestinal epithelium damages the mucosal barrier through direct contact.

    Science.gov (United States)

    Zhang, Chen; Zhang, Hongyu; Yu, Lu; Cao, Yi

    2014-10-01

    Epithelial junctions and mucins compose a major portion of the mucosal barrier. Helicobacter pylori (H. pylori) infections induce alterations of the tight junctions and adherens junctions in epithelial cells, although the precise mechanisms underlying this process are not fully understood. The expression of adhesion molecules and MUC1 was systematically investigated in gastrointestinal epithelial cells infected with H. pylori in vitro and in vivo. Furthermore, we developed several new in vitro methods to study the relationships between the bacterium and the dysfunction of tight junctions using Boyden Chambers. The expression of a series of junctional molecules and MUC1 decreased in the cultured cells that were infected with H. pylori. According to the degree of damage at the tight junctions, direct contact of H. pylori with the apical membrane of the cells resulted in the greatest increase in permeability compared to basal membrane binding or non-binding of H. pylori to the cells. Similarly, we noted that H. pylori infection could reduce the expression and glycosylation of MUC1. Helicobacter pylori dwelling on the apical surface of the gastrointestinal epithelium could directly induce serious injury of the mucosal barrier, and the new methods outlined here, based on the Boyden Chamber system, could be very useful for studying the relationships between bacteria and their target cells. © 2014 John Wiley & Sons Ltd.

  10. Drosophila convoluted/dALS is an essential gene required for tracheal tube morphogenesis and apical matrix organization.

    Science.gov (United States)

    Swanson, Lianna E; Yu, Marcus; Nelson, Kevin S; Laprise, Patrick; Tepass, Ulrich; Beitel, Greg J

    2009-04-01

    Insulin-like growth factors (IGFs) control cell and organism growth through evolutionarily conserved signaling pathways. The mammalian acid-labile subunit (ALS) is a secreted protein that complexes with IGFs to modulate their activity. Recent work has shown that a Drosophila homolog of ALS, dALS, can also complex with and modulate the activity of a Drosophila IGF. Here we report the first mutations in the gene encoding dALS. Unexpectedly, we find that these mutations are allelic to a previously described mutation in convoluted (conv), a gene required for epithelial morphogenesis. In conv mutants, the tubes of the Drosophila tracheal system become abnormally elongated without altering tracheal cell number. conv null mutations cause larval lethality, but do not disrupt several processes required for tracheal tube size control, including septate junction formation, deposition of a lumenal/apical extracellular matrix, and lumenal secretion of Vermiform and Serpentine, two putative matrix-modifying proteins. Clearance of lumenal matrix and subcellular localization of clathrin also appear normal in conv mutants. However, we show that Conv/dALS is required for the dynamic organization of the transient lumenal matrix and normal structure of the cuticle that lines the tracheal lumen. These and other data suggest that the Conv/dALS-dependent tube size control mechanism is distinct from other known processes involved in tracheal tube size regulation. Moreover, we present evidence indicating that Conv/dALS has a novel, IGF-signaling independent function in tracheal morphogenesis.

  11. A Comparative Study of Apical Healing of Open Apices Using MTA and Ca(OH2 Apical Plugs in Cats

    Directory of Open Access Journals (Sweden)

    M. H. Zarrabi

    2005-06-01

    Full Text Available Statement of problem: Endodontic treatment of necrotic teeth with open apices is a challenge. After ruling out surgery as a treatment scheme and introduction of the multivisit apexification which in turn had its disadvantages, apical plug seems to be a suitable substitute treatment plan for such cases. Apical plug makes the treatment through formation of a barrier against the obturating material in a single visit.Purpose: The purpose of this study was to compare histologically the periapical healing using MTA and calcium hydroxide apical plugs after intervals of 4 and 12 weeks in cats.Materials and Methods: In this clinical trial study 64 canines of 16 healthy and mature cats were divided into 3 groups after a periapical lesion formation by over instrumentation in the apical area with files up to no.120. The first group included 24 teeth on which MTA apical plug was applied. The second group included 24 teeth on which Ca (OH 2 apical plug was applied. In both groups the canals were filled with gutta percha and sealer. The third group included 16 control teeth whose canals were left empty after instrumentation and debridement. The access cavities of all teeth were sealed with varnish and amalgam and the vital perfusion of cats was performed in 4 and 12 week intervals. Statistical analysis was established by χ2 and independence test.Results: After 4 weeks, periapical healing in the first group was 90%, in the second group 80% and in the third group, it was only 12.5 %. After 12 weeks, periapical healing occurred in 100% of the MTA group, while it was 57.1% in the second and 40%in the third group .Generally, in the study of histological parameters of healing, no statistical significant difference was observed between the 2 experimental groups,although the MTA group results were much better than the Ca (OH 2 group especially at 12 weeks.Conclusion: The use of MTA apical plug is more effective than Ca (OH 2 in treatment of necrotic teeth with open

  12. c-Yes regulates cell adhesion at the blood-testis barrier and the apical ectoplasmic specialization in the seminiferous epithelium of rat testes.

    Science.gov (United States)

    Xiao, Xiang; Mruk, Dolores D; Lee, Will M; Cheng, C Yan

    2011-04-01

    During spermatogenesis, extensive junction restructuring takes place at the blood-testis barrier (BTB) and the Sertoli cell-spermatid interface known as the apical ectoplasmic specialization (apical ES, a testis-specific adherens junction) in the seminiferous epithelium. However, the mechanism(s) that regulates these critical events in the testis remains unknown. Based on the current concept in the field, changes in the phosphorylation status of integral membrane proteins at these sites can induce alterations in protein endocytosis and recycling, causing junction restructuring. Herein, c-Yes, a non-receptor protein tyrosine kinase, was found to express abundantly at the BTB and apical ES stage-specifically, coinciding with junction restructuring events at these sites during the seminiferous epithelial cycle of spermatogenesis. c-Yes also structurally associated with adhesion proteins at the BTB (e.g., occludin and N-cadherin) and the apical ES (e.g., β1-integrin, laminins β3 and γ3), possibly to regulate phosphorylation status of proteins at these sites. SU6656, a selective c-Yes inhibitor, was shown to perturb the Sertoli cell tight junction-permeability barrier in vitro, which is mediated by changes in the distribution of occludin and N-cadherin at the cell-cell interface, moving from cell surface to cytosol, thereby destabilizing the tight junction-barrier. However, this disruptive effect of SU6656 on the barrier was blocked by testosterone. Furthermore, c-Yes is crucial to maintain the actin filament network in Sertoli cells since a blockade of c-Yes by SU6656 induced actin filament disorganization. In summary, c-Yes regulates BTB and apical ES integrity by maintaining proper distribution of integral membrane proteins and actin filament organization at these sites.

  13. The Dissolution of Double Holliday Junctions

    DEFF Research Database (Denmark)

    Bizard, Anna H; Hickson, Ian D

    2014-01-01

    as "double Holliday junction dissolution." This reaction requires the cooperative action of a so-called "dissolvasome" comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding......) fold containing accessory factor (Rmi1). This review details our current knowledge of the dissolution process and the players involved in catalyzing this mechanistically complex means of completing homologous recombination reactions....

  14. Apical root resorption in orthodontically treated adults.

    Science.gov (United States)

    Baumrind, S; Korn, E L; Boyd, R L

    1996-09-01

    This study analyzed the relationship in orthodontically treated adults between upper central incisor displacement measured on lateral cephalograms and apical root resorption measured on anterior periapical x-ray films. A multiple linear regression examined incisor displacements in four directions (retraction, advancement, intrusion, and extrusion) as independent variables, attempting to account for observed differences in the dependent variable, resorption. Mean apical resorption was 1.36 mm (sd +/- 1.46, n = 73). Mean horizontal displacement of the apex was -0.83 mm (sd +/- 1.74, n = 67); mean vertical displacement was 0.19 mm (sd +/- 1.48, n = 67). The regression coefficients for the intercept and for retraction were highly significant; those for extrusion, intrusion, and advancement were not. At the 95% confidence level, an average of 0.99 mm (se = +/- 0.34) of resorption was implied in the absence of root displacement and an average of 0.49 mm (se = +/- 0.14) of resorption was implied per millimeter of retraction. R2 for all four directional displacement variables (DDVs) taken together was only 0.20, which implied that only a relatively small portion of the observed apical resorption could be accounted for by tooth displacement alone. In a secondary set of univariate analyses, the associations between apical resorption and each of 14 additional treatment-related variables were examined. Only Gender, Elapsed Time, and Total Apical Displacement displayed statistically significant associations with apical resorption. Additional multiple regressions were then performed in which the data for each of these three statistically significant variables were considered separately, with the data for the four directional displacement variables. The addition of information on Elapsed Time or Total Apical Displacement did not explain a significant additional portion of the variability in apical resorption. On the other hand, the addition of information on Gender to the

  15. Microbiology and Treatment of Acute Apical Abscesses

    Science.gov (United States)

    Rôças, Isabela N.

    2013-01-01

    SUMMARY Acute apical abscess is the most common form of dental abscess and is caused by infection of the root canal of the tooth. It is usually localized intraorally, but in some cases the apical abscess may spread and result in severe complications or even mortality. The reasons why dental root canal infections can become symptomatic and evolve to severe spreading and sometimes life-threatening abscesses remain elusive. Studies using culture and advanced molecular microbiology methods for microbial identification in apical abscesses have demonstrated a multispecies community conspicuously dominated by anaerobic bacteria. Species/phylotypes commonly found in these infections belong to the genera Fusobacterium, Parvimonas, Prevotella, Porphyromonas, Dialister, Streptococcus, and Treponema. Advances in DNA sequencing technologies and computational biology have substantially enhanced the knowledge of the microbiota associated with acute apical abscesses and shed some light on the etiopathogeny of this disease. Species richness and abundance and the resulting network of interactions among community members may affect the collective pathogenicity and contribute to the development of acute infections. Disease modifiers, including transient or permanent host-related factors, may also influence the development and severity of acute abscesses. This review focuses on the current evidence about the etiology and treatment of acute apical abscesses and how the process is influenced by host-related factors and proposes future directions in research, diagnosis, and therapeutic approaches to deal with this disease. PMID:23554416

  16. Effect of Maintaining Apical Patency on Irrigant Penetration into the Apical Two Millimeters of Large Root Canals : An In Vivo Study

    NARCIS (Netherlands)

    Vera, Jorge; Hernandez, Erick M.; Romero, Monica; Arias, Ana; van der Sluis, Lucas W. M.

    2012-01-01

    Introduction: Factors such as complex root canal anatomy and the vapor lock phenomenon have been shown to limit the penetration of irrigating solutions into the apical third in both in vivo and in vitro studies involving small and wide canals. Hence, the aim of this study was to determine whether

  17. The Downside of Right Ventricular Apical Pacing

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    Andrew Brenyo, MD

    2012-05-01

    Full Text Available The right ventricular (RV apex has been the standard pacing site since the development of implantable pacemaker technology. Although RV pacing was initially only utilized for the treatment of severe bradyarrhythmias usually due to complete heart block, today the indications for and implantation of RV pacing devices is dramatically larger. Recently, the adverse effects of chronic RV apical pacing have been described including an increased risk of heart failure and death. This review details the detrimental effects of RV apical pacing and their shared hemodynamic pathophysiology. In particular, the role of RV apical pacing induced ventricular dyssynchrony is highlighted with a specific focus on differential outcome based upon QRS morphology at implant.

  18. Molecular electronic junction transport

    DEFF Research Database (Denmark)

    Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

    2012-01-01

    Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and f...

  19. Tight junction disruption induced by type 3 secretion system effectors injected by Enteropathogenic and Enterohemorrhagic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Paul Ugalde-Silva

    2016-08-01

    Full Text Available The intestinal epithelium consists of a single cell layer, which is a critical selectively permeable barrier to both absorb nutrients and avoid the entry of potentially harmful entities, including microorganisms. Epithelial cells are held together by the apical junctional complexes, consisting of adherens junctions and tight junctions (TJs, and by underlying desmosomes. TJs lay in the apical domain of epithelial cells and are mainly composed by transmembrane proteins such as occludin, claudins, JAMs, and tricellulin, that are associated with the cytoplasmic plaque formed by proteins from the MAGUK family, such as ZO-1/2/3, connecting TJ to the actin cytoskeleton, and cingulin and paracingulin connecting TJ to the microtubule network. Extracellular bacteria such as EPEC and EHEC living in the intestinal lumen inject effectors proteins directly from the bacterial cytoplasm to the host cell cytoplasm, where they play a relevant role in the manipulation of the eukaryotic cell functions by modifying or blocking cell signaling pathways. TJ integrity depends on various cell functions such as actin cytoskeleton, microtubule network for vesicular trafficking, membrane integrity, inflammation, and cell survival. EPEC and EHEC effectors target most of these functions. Effectors encoded inside or outside of locus of enterocyte effacement (LEE disrupt the TJ strands. EPEC and EHEC exploit the TJ dynamics to open this structure, for causing diarrhea. EPEC and EHEC secrete effectors that mimic host proteins to manipulate the signaling pathways, including those related to TJ dynamics. In this review, we focus on the known mechanisms exploited by EPEC and EHEC effectors for causing TJ disruption.

  20. Molecular insights into the interaction between Plasmodium falciparum apical membrane antigen 1 and an invasion-inhibitory peptide.

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    Geqing Wang

    Full Text Available Apical membrane antigen 1 (AMA1 of the human malaria parasite Plasmodium falciparum has been implicated in invasion of the host erythrocyte. It interacts with malarial rhoptry neck (RON proteins in the moving junction that forms between the host cell and the invading parasite. Agents that block this interaction inhibit invasion and may serve as promising leads for anti-malarial drug development. The invasion-inhibitory peptide R1 binds to a hydrophobic cleft on AMA1, which is an attractive target site for small molecules that block parasite invasion. In this work, truncation and mutational analyses show that Phe5-Phe9, Phe12 and Arg15 in R1 are the most important residues for high affinity binding to AMA1. These residues interact with two well-defined binding hot spots on AMA1. Computational solvent mapping reveals that one of these hot spots is suitable for small molecule targeting. We also confirm that R1 in solution binds to AMA1 with 1:1 stoichiometry and adopts a secondary structure consistent with the major form of R1 observed in the crystal structure of the complex. Our results provide a basis for designing high affinity inhibitors of the AMA1-RON2 interaction.

  1. Multilevel Precision-Based Rational Design of Chemical Inhibitors Targeting the Hydrophobic Cleft of Toxoplasma gondii Apical Membrane Antigen 1 (AMA1)

    Science.gov (United States)

    Muralikumar, Shalini; Mahalakshmi, B; Lily Therese, K; Madhavan, HN; Alameen, Mohamed; Thirumudi, Indhuja

    2016-01-01

    Toxoplasma gondii is an intracellular Apicomplexan parasite and a causative agent of toxoplasmosis in human. It causes encephalitis, uveitis, chorioretinitis, and congenital infection. T. gondii invades the host cell by forming a moving junction (MJ) complex. This complex formation is initiated by intermolecular interactions between the two secretory parasitic proteins—namely, apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2) and is critically essential for the host invasion process. By this study, we propose two potential leads, NSC95522 and NSC179676 that can efficiently target the AMA1 hydrophobic cleft, which is a hotspot for targeting MJ complex formation. The proposed leads are the result of an exhaustive conformational search-based virtual screen with multilevel precision scoring of the docking affinities. These two compounds surpassed all the precision levels of docking and also the stringent post docking and cumulative molecular dynamics evaluations. Moreover, the backbone flexibility of hotspot residues in the hydrophobic cleft, which has been previously reported to be essential for accommodative binding of RON2 to AMA1, was also highly perturbed by these compounds. Furthermore, binding free energy calculations of these two compounds also revealed a significant affinity to AMA1. Machine learning approaches also predicted these two compounds to possess more relevant activities. Hence, these two leads, NSC95522 and NSC179676, may prove to be potential inhibitors targeting AMA1-RON2 complex formation towards combating toxoplasmosis. PMID:27445648

  2. Multilevel Precision-Based Rational Design of Chemical Inhibitors Targeting the Hydrophobic Cleft of Toxoplasma gondii Apical Membrane Antigen 1 (AMA1).

    Science.gov (United States)

    Vetrivel, Umashankar; Muralikumar, Shalini; Mahalakshmi, B; Lily Therese, K; Madhavan, H N; Alameen, Mohamed; Thirumudi, Indhuja

    2016-06-01

    Toxoplasma gondii is an intracellular Apicomplexan parasite and a causative agent of toxoplasmosis in human. It causes encephalitis, uveitis, chorioretinitis, and congenital infection. T. gondii invades the host cell by forming a moving junction (MJ) complex. This complex formation is initiated by intermolecular interactions between the two secretory parasitic proteins-namely, apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2) and is critically essential for the host invasion process. By this study, we propose two potential leads, NSC95522 and NSC179676 that can efficiently target the AMA1 hydrophobic cleft, which is a hotspot for targeting MJ complex formation. The proposed leads are the result of an exhaustive conformational search-based virtual screen with multilevel precision scoring of the docking affinities. These two compounds surpassed all the precision levels of docking and also the stringent post docking and cumulative molecular dynamics evaluations. Moreover, the backbone flexibility of hotspot residues in the hydrophobic cleft, which has been previously reported to be essential for accommodative binding of RON2 to AMA1, was also highly perturbed by these compounds. Furthermore, binding free energy calculations of these two compounds also revealed a significant affinity to AMA1. Machine learning approaches also predicted these two compounds to possess more relevant activities. Hence, these two leads, NSC95522 and NSC179676, may prove to be potential inhibitors targeting AMA1-RON2 complex formation towards combating toxoplasmosis.

  3. Cell division activity during apical hook development

    NARCIS (Netherlands)

    Raz, V.; Koornneef, M.

    2001-01-01

    Growth during plant development is predominantly governed by the combined activities of cell division and cell elongation. The relative contribution of both activities controls the growth of a tissue. A fast change in growth is exhibited at the apical hypocotyl of etiolated seedlings where cells

  4. Cell division activity during apical hook development

    NARCIS (Netherlands)

    Raz, V.; Koornneef, M.

    2001-01-01

    Growth during plant development is predominantly governed by the combined activities of cell division and cell elongation. The relative contribution of both activities controls the growth of a tissue. A fast change in growth is exhibited at the apical hypocotyl of etiolated seedlings where cells gro

  5. Normal apical pleural tenting: CT findings

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Dong Wook; Yoon, Yup; Jeong, Yu Mee; Park, Joo Chul; Cho, Kyu Seok; Ahn, Hee Kyung; Lee, Won Kyu [Kyunghee Univ. College of Medicine, Seoul (Korea, Republic of)

    1996-07-01

    To define the anatomy of apical pleural tenting commonly seen in computed tomography(CT) of the upper posterior thorax. Chest CTs of 393 patients with no pleural disease clinically and radiographically were analyzed. GE-9800 Quick and Toshiba-900S were used, employing the usual contrast enhanced CT technique. CT findings of focal pleural tenting on the inner side of the upper posterior thorax(apical pleural tenting) were evalvated and analysed in terms of location and shape. The CT findings were compared with the gross findings of the inner aspect of the posterior cadaveric thorax. Apical pleural tenting was formed by the upper border of the subcostal muscle. It's incidence was 44%(n=171), with bilaterality in 29%(n=49), and unilaterality in 71% of cases(n=122). This tenting was most frequently found between the third rib and the fourth intercostal space(81%), and seen in the outer third(42%) or central third(41%) part of the posterior costal pleura. In fifteen cases(7%), it was directed obliquely and had changed its location from the inner to the central or the central to the outer part. The shapes of the tenting were classified as follows:type 1(convex inner border with sharp apex, 62%); type 2(convex inner border with broad apex, 23%);type 3(undulated contour of apex, 13%);and type 4(two-spike apices, 1%). Apical pleura tenting is a normal CT finding probably demonstrated by the upper border of the subcostal muscle. Misdiagnosis of pleural disease can be avoided by recognition of the location and type of this tenting.

  6. Rac1 controls epithelial tube length through the apical secretion and polarity pathways

    Directory of Open Access Journals (Sweden)

    Kévin Sollier

    2016-01-01

    Full Text Available The morphometric parameters of epithelial tubes are critical to the physiology and homeostasis of most organs. In addition, many human diseases are associated with tube-size defects. Here, we show that Rac1 limits epithelial tube elongation in the developing fly trachea by promoting Rab5-dependent endocytosis of the apical determinant Crumbs. Rac1 is also involved in a positive feedback loop with the septate junction protein Coracle. Thereby, Rac1 precludes paracellular diffusion and contributes to the septate junction-dependent secretion of the chitin-modifying enzymes Vermiform and Serpentine, which restrict epithelial tube length independently of Crumbs. Thus, Rac1 is a critical component of two important pathways controlling epithelial tube morphogenesis.

  7. Rac1 controls epithelial tube length through the apical secretion and polarity pathways

    Science.gov (United States)

    Sollier, Kévin; Gaudé, Helori-Mael; Chartier, François J.-M.; Laprise, Patrick

    2016-01-01

    ABSTRACT The morphometric parameters of epithelial tubes are critical to the physiology and homeostasis of most organs. In addition, many human diseases are associated with tube-size defects. Here, we show that Rac1 limits epithelial tube elongation in the developing fly trachea by promoting Rab5-dependent endocytosis of the apical determinant Crumbs. Rac1 is also involved in a positive feedback loop with the septate junction protein Coracle. Thereby, Rac1 precludes paracellular diffusion and contributes to the septate junction-dependent secretion of the chitin-modifying enzymes Vermiform and Serpentine, which restrict epithelial tube length independently of Crumbs. Thus, Rac1 is a critical component of two important pathways controlling epithelial tube morphogenesis. PMID:26700724

  8. PLEKHA7 is an adherens junction protein with a tissue distribution and subcellular localization distinct from ZO-1 and E-cadherin.

    Directory of Open Access Journals (Sweden)

    Pamela Pulimeno

    Full Text Available The pleckstrin-homology-domain-containing protein PLEKHA7 was recently identified as a protein linking the E-cadherin-p120 ctn complex to the microtubule cytoskeleton. Here we characterize the expression, tissue distribution and subcellular localization of PLEKHA7 by immunoblotting, immunofluorescence microscopy, immunoelectron microscopy, and northern blotting in mammalian tissues. Anti-PLEKHA7 antibodies label the junctional regions of cultured kidney epithelial cells by immunofluorescence microscopy, and major polypeptides of M(r approximately 135 kDa and approximately 145 kDa by immunoblotting of lysates of cells and tissues. Two PLEKHA7 transcripts ( approximately 5.5 kb and approximately 6.5 kb are detected in epithelial tissues. PLEKHA7 is detected at epithelial junctions in sections of kidney, liver, pancreas, intestine, retina, and cornea, and its tissue distribution and subcellular localization are distinct from ZO-1. For example, PLEKHA7 is not detected within kidney glomeruli. Similarly to E-cadherin, p120 ctn, beta-catenin and alpha-catenin, PLEKHA7 is concentrated in the apical junctional belt, but unlike these adherens junction markers, and similarly to afadin, PLEKHA7 is not localized along the lateral region of polarized epithelial cells. Immunoelectron microscopy definitively establishes that PLEKHA7 is localized at the adherens junctions in colonic epithelial cells, at a mean distance of 28 nm from the plasma membrane. In summary, we show that PLEKHA7 is a cytoplasmic component of the epithelial adherens junction belt, with a subcellular localization and tissue distribution that is distinct from that of ZO-1 and most AJ proteins, and we provide the first description of its distribution and localization in several tissues.

  9. Apical domain polarization localizes actin-myosin activity to drive ratchet-like apical constriction

    OpenAIRE

    Mason, Frank M.; Tworoger, Michael; Martin, Adam C.

    2013-01-01

    Apical constriction promotes epithelia folding, which changes tissue architecture. During Drosophila gastrulation, mesoderm cells exhibit repeated contractile pulses that are stabilized such that cells apically constrict like a ratchet. The transcription factor Twist is required to stabilize cell shape, however it is unknown how Twist spatially coordinates downstream signals to prevent cell relaxation. We find that during constriction, Rho-associated kinase (Rok) is polarized to the middle of...

  10. Clinical study of refractory apical periodontitis treated by apicectomy. Part 1. Root canal morphology of resected apex.

    Science.gov (United States)

    Wada, M; Takase, T; Nakanuma, K; Arisue, K; Nagahama, F; Yamazaki, M

    1998-01-01

    The morphology of the root apex was analysed by observation of the anatomy of specimens obtained by apicoectomy in cases of refractory apical periodontitis that did not respond to nonsurgical root canal treatment. Apical ramifications were present in 19 (70%) of the roots, while one were found in the remaining eight (3%) roots. This frequency is far higher than that reported by other investigators, suggesting that there is a close relationship between the anatomical complexity of the root canal and the occurrence of refractory apical periodontitis.

  11. Tight junction protein Par6 interacts with an evolutionarily conserved region in the amino terminus of PALS1/stardust.

    Science.gov (United States)

    Wang, Qian; Hurd, Toby W; Margolis, Ben

    2004-07-16

    Tight junctions are the structures in mammalian epithelial cells that separate the apical and basolateral membranes and may also be important in the establishment of cell polarity. Two evolutionarily conserved multiprotein complexes, Crumbs-PALS1 (Stardust)-PATJ and Cdc42-Par6-Par3-atypical protein kinase C, have been implicated in the assembly of tight junctions and in polarization of Drosophila melanogaster epithelia. These two complexes have been linked physically and functionally by an interaction between PALS1 and Par6. Here we identify an evolutionarily conserved region in the amino terminus of PALS1 as the Par6 binding site and identify valine and aspartic acid residues in this region as essential for interacting with the PDZ domain of Par6. We have also characterized, in more detail, the amino terminus of Drosophila Stardust and demonstrate that the interaction mechanism between Stardust and Drosophila Par6 is evolutionarily conserved. Par6 interferes with PATJ in binding PALS1, and these two interactions do not appear to function synergistically. Taken together, these results define the molecular mechanisms linking two conserved polarity complexes.

  12. An Extended Surface Loop on Toxoplasma gondii Apical Membrane Antigen 1 (AMA1 Governs Ligand Binding Selectivity.

    Directory of Open Access Journals (Sweden)

    Michelle L Parker

    Full Text Available Apicomplexan parasites are the causative agents of globally prevalent diseases including malaria and toxoplasmosis. These obligate intracellular pathogens have evolved a sophisticated host cell invasion strategy that relies on a parasite-host cell junction anchored by interactions between apical membrane antigens (AMAs on the parasite surface and rhoptry neck 2 (RON2 proteins discharged from the parasite and embedded in the host cell membrane. Key to formation of the AMA1-RON2 complex is displacement of an extended surface loop on AMA1 called the DII loop. While conformational flexibility of the DII loop is required to expose the mature RON2 binding groove, a definitive role of this substructure has not been elucidated. To establish a role of the DII loop in Toxoplasma gondii AMA1, we engineered a form of the protein where the mobile portion of the loop was replaced with a short Gly-Ser linker (TgAMA1ΔDIIloop. Isothermal titration calorimetry measurements with a panel of RON2 peptides revealed an influential role for the DII loop in governing selectivity. Most notably, an Eimeria tenella RON2 (EtRON2 peptide that showed only weak binding to TgAMA1 bound with high affinity to TgAMA1ΔDIIloop. To define the molecular basis for the differential binding, we determined the crystal structure of TgAMA1ΔDIIloop in complex with the EtRON2 peptide. When analyzed in the context of existing AMA1-RON2 structures, spatially distinct anchor points in the AMA1 groove were identified that, when engaged, appear to provide the necessary traction to outcompete the DII loop. Collectively, these data support a model where the AMA1 DII loop serves as a structural gatekeeper to selectively filter out ligands otherwise capable of binding with high affinity in the AMA1 apical groove. These data also highlight the importance of considering the functional implications of the DII loop in the ongoing development of therapeutic intervention strategies targeting the AMA1-RON

  13. Shear zone junctions: Of zippers and freeways

    Science.gov (United States)

    Passchier, Cees W.; Platt, John P.

    2017-02-01

    Ductile shear zones are commonly treated as straight high-strain domains with uniform shear sense and characteristic curved foliation trails, bounded by non-deforming wall rock. Many shear zones, however, are branched, and if movement on such branches is contemporaneous, the resulting shape can be complicated and lead to unusual shear sense arrangement and foliation geometries in the wall rock. For Y-shaped shear zone triple junctions with three joining branches and transport direction at a high angle to the branchline, only eight basic types of junction are thought to be stable and to produce significant displacement. The simplest type, called freeway junctions, have similar shear sense in all three branches. The other types show joining or separating behaviour of shear zone branches similar to the action of a zipper. Such junctions may have shear zone branches that join to form a single branch (closing zipper junction), or a single shear zone that splits to form two branches, (opening zipper junction). All categories of shear zone junctions show characteristic foliation patterns and deflection of markers in the wall rock. Closing zipper junctions are unusual, since they form a non-active zone with opposite deflection of foliations in the wall rock known as an extraction fault or wake. Shear zipper junctions can form domains of overprinting shear sense along their flanks. A small and large field example are given from NE Spain and Eastern Anatolia. The geometry of more complex, 3D shear zone junctions with slip parallel and oblique to the branchline is briefly discussed.

  14. Gene knockout using transcription activator-like effector nucleases (TALENs) reveals that human NDUFA9 protein is essential for stabilizing the junction between membrane and matrix arms of complex I.

    Science.gov (United States)

    Stroud, David A; Formosa, Luke E; Wijeyeratne, Xiaonan W; Nguyen, Thanh N; Ryan, Michael T

    2013-01-18

    Transcription activator-like effector nucleases (TALENs) represent a promising approach for targeted knock-out of genes in cultured human cells. We used TALEN-technology to knock out the nuclear gene encoding NDUFA9, a subunit of mitochondrial respiratory chain complex I in HEK293T cells. Screening for the knock-out revealed a mixture of NDUFA9 cell clones that harbored partial deletions of the mitochondrial N-terminal targeting signal but were still capable of import. A cell line lacking functional copies of both NDUFA9 alleles resulted in a loss of NDUFA9 protein expression, impaired assembly of complex I, and cells incapable of growth in galactose medium. Cells lacking NDUFA9 contained a complex I subcomplex consisting of membrane arm subunits but not marker subunits of the matrix arm. Re-expression of NDUFA9 restored the defects in complex I assembly. We conclude that NDUFA9 is involved in stabilizing the junction between membrane and matrix arms of complex I, a late assembly step critical for complex I biogenesis and activity.

  15. Mechanical roles of apical constriction, cell elongation, and cell migration during neural tube formation in Xenopus.

    Science.gov (United States)

    Inoue, Yasuhiro; Suzuki, Makoto; Watanabe, Tadashi; Yasue, Naoko; Tateo, Itsuki; Adachi, Taiji; Ueno, Naoto

    2016-12-01

    Neural tube closure is an important and necessary process during the development of the central nervous system. The formation of the neural tube structure from a flat sheet of neural epithelium requires several cell morphogenetic events and tissue dynamics to account for the mechanics of tissue deformation. Cell elongation changes cuboidal cells into columnar cells, and apical constriction then causes them to adopt apically narrow, wedge-like shapes. In addition, the neural plate in Xenopus is stratified, and the non-neural cells in the deep layer (deep cells) pull the overlying superficial cells, eventually bringing the two layers of cells to the midline. Thus, neural tube closure appears to be a complex event in which these three physical events are considered to play key mechanical roles. To test whether these three physical events are mechanically sufficient to drive neural tube formation, we employed a three-dimensional vertex model and used it to simulate the process of neural tube closure. The results suggest that apical constriction cued the bending of the neural plate by pursing the circumference of the apical surface of the neural cells. Neural cell elongation in concert with apical constriction further narrowed the apical surface of the cells and drove the rapid folding of the neural plate, but was insufficient for complete neural tube closure. Migration of the deep cells provided the additional tissue deformation necessary for closure. To validate the model, apical constriction and cell elongation were inhibited in Xenopus laevis embryos. The resulting cell and tissue shapes resembled the corresponding simulation results.

  16. A Case of Persistent Apical Ballooning Complicated by Apical Thrombus in Takotsubo Cardiomyopathy of Systemic Lupus Erythematosus Patient

    National Research Council Canada - National Science Library

    Shim, In Kyoung; Kim, Bong-Joon; Kim, Hyunsu; Lee, Jae-Woo; Cha, Tae-Joon; Heo, Jung Ho

    2013-01-01

    .... The prognosis is favorable with the normalization of wall motion abnormalities within weeks. We report a case of persistent apical ballooning complicated by an apical thrombus in Takotsubo cardiomyopathy of systemic lupus erythematous patient...

  17. Tight Junctions in Salivary Epithelium

    Directory of Open Access Journals (Sweden)

    Olga J. Baker

    2010-01-01

    Full Text Available Epithelial cell tight junctions (TJs consist of a narrow belt-like structure in the apical region of the lateral plasma membrane that circumferentially binds each cell to its neighbor. TJs are found in tissues that are involved in polarized secretions, absorption functions, and maintaining barriers between blood and interstitial fluids. The morphology, permeability, and ion selectivity of TJ vary among different types of tissues and species. TJs are very dynamic structures that assemble, grow, reorganize, and disassemble during physiological or pathological events. Several studies have indicated the active role of TJ in intestinal, renal, and airway epithelial function; however, the functional significance of TJ in salivary gland epithelium is poorly understood. Interactions between different combinations of the TJ family (each with their own unique regulatory proteins define tissue specificity and functions during physiopathological processes; however, these interaction patterns have not been studied in salivary glands. The purpose of this review is to analyze some of the current data regarding the regulatory components of the TJ that could potentially affect cellular functions of the salivary epithelium.

  18. Type III apical transportation of root canal

    Directory of Open Access Journals (Sweden)

    Shiv P Mantri

    2012-01-01

    Full Text Available Procedural accidents leading to complications such as canal transportation have been ascribed to inapt cleaning and shaping concepts. Canal transportation is an undesirable deviation from the natural canal path. Herewith a case of apical transportation of root canal resulting in endodontic retreatment failure and its management is presented. A healthy 21-year-old young male presented discomfort and swelling associated with painful endodontically retreated maxillary incisor. Radiograph revealed periradicular radiolucency involving underfilled 11 and overfilled 12. Insufficiently obturated 11 exhibited apical transportation of canal. This type III transportation was treated by periradicular surgery and repair using white mineral trioxide aggregate (MTA. Comfortable asymptomatic patient presented uneventful healing at third and fourth month recall visits. A decrease in the size of radiolucency in radiograph supported the clinical finding. In the present case, MTA is useful in repairing the transportation defect. The result of these procedures is predictable and successful.

  19. Fat1 interacts with Fat4 to regulate neural tube closure, neural progenitor proliferation and apical constriction during mouse brain development.

    Science.gov (United States)

    Badouel, Caroline; Zander, Mark A; Liscio, Nicole; Bagherie-Lachidan, Mazdak; Sopko, Richelle; Coyaud, Etienne; Raught, Brian; Miller, Freda D; McNeill, Helen

    2015-08-15

    Mammalian brain development requires coordination between neural precursor proliferation, differentiation and cellular organization to create the intricate neuronal networks of the adult brain. Here, we examined the role of the atypical cadherins Fat1 and Fat4 in this process. We show that mutation of Fat1 in mouse embryos causes defects in cranial neural tube closure, accompanied by an increase in the proliferation of cortical precursors and altered apical junctions, with perturbations in apical constriction and actin accumulation. Similarly, knockdown of Fat1 in cortical precursors by in utero electroporation leads to overproliferation of radial glial precursors. Fat1 interacts genetically with the related cadherin Fat4 to regulate these processes. Proteomic analysis reveals that Fat1 and Fat4 bind different sets of actin-regulating and junctional proteins. In vitro data suggest that Fat1 and Fat4 form cis-heterodimers, providing a mechanism for bringing together their diverse interactors. We propose a model in which Fat1 and Fat4 binding coordinates distinct pathways at apical junctions to regulate neural progenitor proliferation, neural tube closure and apical constriction.

  20. Evaluation of three instrumentation techniques at the precision of apical stop and apical sealing of obturation

    Science.gov (United States)

    GENÇ, Özgür; ALAÇAM, Tayfun; KAYAOGLU, Guven

    2011-01-01

    Objective The aim of this study was to investigate the ability of two NiTi rotary apical preparation techniques used with an electronic apex locator-integrated endodontic motor and a manual technique to create an apical stop at a predetermined level (0.5 mm short of the apical foramen) in teeth with disrupted apical constriction, and to evaluate microleakage following obturation in such prepared teeth. Material and Methods: 85 intact human mandibular permanent incisors with single root canal were accessed and the apical constriction was disrupted using a #25 K-file. The teeth were embedded in alginate and instrumented to #40 using rotary Lightspeed or S-Apex techniques or stainless-steel K-files. Distance between the apical foramen and the created apical stop was measured to an accuracy of 0.01 mm. In another set of instrumented teeth, root canals were obturated using gutta-percha and sealer, and leakage was tested at 1 week and 3 months using a fluid filtration device. Results All techniques performed slightly short of the predetermined level. Closest preparation to the predetermined level was with the manual technique and the farthest was with S-Apex. A significant difference was found between the performances of these two techniques (p<0.05). Lightspeed ranked in between. Leakage was similar for all techniques at either period. However, all groups leaked significantly more at 3 months compared to 1 week (p<0.05). Conclusions Despite statistically significant differences found among the techniques, deviations from the predetermined level were small and clinically acceptable for all techniques. Leakage following obturation was comparable in all groups. PMID:21655774

  1. Evaluation of three instrumentation techniques at the precision of apical stop and apical sealing of obturation

    Directory of Open Access Journals (Sweden)

    Özgür Genç

    2011-08-01

    Full Text Available OBJECTIVE: The aim of this study was to investigate the ability of two NiTi rotary apical preparation techniques used with an electronic apex locator-integrated endodontic motor and a manual technique to create an apical stop at a predetermined level (0.5 mm short of the apical foramen in teeth with disrupted apical constriction, and to evaluate microleakage following obturation in such prepared teeth. MATERIAL AND METHODS: 85 intact human mandibular permanent incisors with single root canal were accessed and the apical constriction was disrupted using a #25 K-file. The teeth were embedded in alginate and instrumented to #40 using rotary Lightspeed or S-Apex techniques or stainless-steel K-files. Distance between the apical foramen and the created apical stop was measured to an accuracy of 0.01 mm. In another set of instrumented teeth, root canals were obturated using gutta-percha and sealer, and leakage was tested at 1 week and 3 months using a fluid filtration device. RESULTS: All techniques performed slightly short of the predetermined level. Closest preparation to the predetermined level was with the manual technique and the farthest was with S-Apex. A significant difference was found between the performances of these two techniques (p<0.05. Lightspeed ranked in between. Leakage was similar for all techniques at either period. However, all groups leaked significantly more at 3 months compared to 1 week (p<0.05. CONCLUSIONS: Despite statistically significant differences found among the techniques, deviations from the predetermined level were small and clinically acceptable for all techniques. Leakage following obturation was comparable in all groups.

  2. Auxin at the shoot apical meristem

    OpenAIRE

    Vernoux, Teva; Besnard, Fabrice; Traas, Jan

    2010-01-01

    Plants continuously generate new tissues and organs through the activity of populations of undifferentiated stem cells, called meristems. Here, we discuss the so-called shoot apical meristem (SAM), which generates all the aerial parts of the plant. It has been known for many years that auxin plays a central role in the functioning of this meristem. Auxin is not homogeneously distributed at the SAM and it is thought that this distribution is interpreted in terms of differential gene expression...

  3. Pathogenesis of Apical Periodontitis: a Literature Review

    OpenAIRE

    2012-01-01

    ABSTRACT Objectives This review article discusses the host response in apical periodontitis with the main focus on cytokines, produced under this pathological condition and contributing to the degradation of periradicular tissues. The pace of research in this field has greatly accelerated in the last decade. Here we provide an analysis of studies published in this area during this period. Material and methods Literature was selected through a search of PubMed electronic database. The keywords...

  4. Fractal dimension of apical dendritic arborization differs in the superficial and the deep pyramidal neurons of the rat cerebral neocortex.

    Science.gov (United States)

    Puškaš, Nela; Zaletel, Ivan; Stefanović, Bratislav D; Ristanović, Dušan

    2015-03-04

    Pyramidal neurons of the mammalian cerebral cortex have specific structure and pattern of organization that involves the presence of apical dendrite. Morphology of the apical dendrite is well-known, but quantification of its complexity still remains open. Fractal analysis has proved to be a valuable method for analyzing the complexity of dendrite morphology. The aim of this study was to establish the fractal dimension of apical dendrite arborization of pyramidal neurons in distinct neocortical laminae by using the modified box-counting method. A total of thirty, Golgi impregnated neurons from the rat brain were analyzed: 15 superficial (cell bodies located within lamina II-III), and 15 deep pyramidal neurons (cell bodies situated within lamina V-VI). Analysis of topological parameters of apical dendrite arborization showed no statistical differences except in total dendritic length (p=0.02), indicating considerable homogeneity between the two groups of neurons. On the other hand, average fractal dimension of apical dendrite was 1.33±0.06 for the superficial and 1.24±0.04 for the deep cortical neurons, showing statistically significant difference between these two groups (pfractal dimension values, apical dendrites of the superficial pyramidal neurons tend to show higher structural complexity compared to the deep ones.

  5. Shoot Apical Meristem Organization in Several Philippine Species of Selaginella

    Directory of Open Access Journals (Sweden)

    Prescillano Zamora

    1993-06-01

    Full Text Available This paper reports for the first time the occurrence of two types of shoot apical meristem organization on the main and lateral shoots of eight Philippine species of Selaginella: (1 shoot apical meristem with a single lenticular apical cell in S. cupressina and S. delicatula and (a shoot apical meristem with a row of several prominent prismatic apical cells in the lateral plane in S. jagorii, S. halconensis, S. involvens (S. polyura, S. peltata, S. flagellifera (S. biformis, S. nummularia, S. aristata, and S. philippina (endemic.

  6. The Drosophila genes crumbs and stardust are involved in the biogenesis of adherens junctions.

    Science.gov (United States)

    Grawe, F; Wodarz, A; Lee, B; Knust, E; Skaer, H

    1996-03-01

    Morphogenetic movements of epithelia during development underlie the normal elaboration of the final body plan. The tissue integrity critical for these movements is conferred by anchorage of the cytoskeleton by adherens junctions, initially spot and later belt-like, zonular structures, which encircle the apical side of the cell. Loss-of-function mutations in the Drosophila genes crumbs and stardust lead to the loss of cell polarity in most ectodermally derived epithelia, followed in some, such as the epidermis, by extensive apoptosis. Here we show that both mutants fail to establish proper zonulae adherentes in the epidermis. Our results suggest that the two genes are involved in different aspects of this process. Further, they are compatible with the hypothesis that crumbs delimits the apical border, where the zonula adherens usually forms and where Crumbs protein is normally most abundant. In contrast, stardust seems to be required at an earlier stage for the assembly of the spot adherence junctions. In both mutants, the defect observed at the ultrastructural level are preceded by a misdistribution of Armadillo and DE-cadherin, the homologues of beta-catenin and E-cadherin, respectively, which are two constituents of the vertebrate adherens junctions. Strikingly, expansion of the apical membrane domain in epidermal cells by overexpression of crumbs also abolishes the formation of adherens junctions and results in the disruption of tissue integrity, but without loss of membrane polarity. This result supports the view that membrane polarity is independent of the formation of adherens junctions in epidermal cells.

  7. Architecture of apical dendrites in the murine neocortex: dual apical dendritic systems.

    Science.gov (United States)

    Escobar, M I; Pimienta, H; Caviness, V S; Jacobson, M; Crandall, J E; Kosik, K S

    1986-04-01

    A monoclonal antibody (5F9) against microtubule-associated protein 2 is a selective and sensitive marker for neocortical dendrites in the mouse. The marker stains all dendrites. It affords a particularly comprehensive picture of the patterns of arrangements of apical dendrites which are most intensely stained with this antibody. Dual systems of apical dendrites arise from the polymorphic neurons of layer VI, on the one hand, and the pyramidal neurons of layers II-V, on the other. Terminal arborization of the former is concentrated principally at the interface of layers V and IV, while that of the latter is in the molecular layer. Apical dendrites of both systems are grouped into fascicles. In supragranular layers and in upper layer VI-lower layer V, where apical dendrites are most abundant, the fascicles coalesce into septa. These generate a honeycomb-like pattern, subdividing these cortical levels into columnar spaces of approximately 20-40 micron diameter. At the level of layer IV, where the number of apical dendrites is greatly reduced, the fascicles are isolated bundles. These bundles have the form of circular, elliptical or rectangular columns in the primary somatosensory, temporal and frontal regions, respectively. Those in the barrel field are preferentially concentrated in the sides of barrels and the interbarrel septa. The configurations of the dendritic fascicles, particularly the midcortical bundles, may conform to the spatial configuration of investing axons of interneurons.

  8. Morphogenesis of rat myotendinous junction.

    Science.gov (United States)

    Curzi, Davide; Ambrogini, Patrizia; Falcieri, Elisabetta; Burattini, Sabrina

    2013-10-01

    Myotendinous junction (MTJ) is the highly specialized complex which connects the skeletal muscle to the tendon for transmitting the contractile force between the two tissues. The purpose of this study was to investigate the MTJ development and rat EDL was chosen as a model. 1, 15, 30 day animals were considered and the junctions were analyzed by light and electron microscopy. The MTJ interface architecture increased during the development, extending the interaction between muscle and tendon. 1-day-old rats showed disorganized myofibril bundles, spread cytosol and incomplete rough endoplasmic reticulum, features partially improved in 15-day-old rats, and completely developed in 30-day-old animals. These findings indicate that muscle-tendon interface displays, during rat lifetime, numerically increased and longer tendon interdigitations, correlated with an improved organization of both tissues and with a progressive acquirement of full functionality.

  9. Magnetic tunnel junctions (MTJs)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We review the giant tunnel magnetoresistance (TMR) in ferromagnetic-insulator-ferromagnetic junctions discovered in recent years, which is the magnetoresistance (MR) associated with the spin-dependent tunneling between two ferromagnetic metal films separated by an insulating thin tunnel barrier. The theoretical and experimental results including junction conductance, magnetoresistance and their temperature and bias dependences are described.

  10. Stacked Josephson Junctions

    DEFF Research Database (Denmark)

    Madsen, Søren Find; Pedersen, Niels Falsig; Christiansen, Peter Leth

    2010-01-01

    Long Josephson junctions have for some time been considered as a source of THz radiation. Solitons moving coherently in the junctions is a possible source for this radiation. Analytical computations of the bunched state and bunching-inducing methods are reviewed. Experiments showing THz radiation...

  11. Minimal Apical Enlargement for Penetration of Irrigants to the Apical Third of Root Canal System: A Scanning Electron Microscope Study

    Science.gov (United States)

    Srikanth, P; Krishna, Amaravadi Gopi; Srinivas, Siva; Reddy, E Sujayeendranatha; Battu, Someshwar; Aravelli, Swathi

    2015-01-01

    Background: The aim of this study was to determine minimal apical enlargement for irrigant penetration into apical third of root canal system using scanning electron microscope (SEM). Materials and Methods: Distobuccal canals of 40 freshly extracted human maxillary first molar teeth were instrumented using crown-down technique. The teeth were divided into four test groups according to size of their master apical file (MAF) (#20, #25, #30, #35 0.06% taper), and two control groups. After final irrigation, removal of debris and smear layer from the apical third of root canals was determined under a SEM. Data was analyzed using Kruskal–Wallis and Mann–Whitney tests. Results: Smear layer removal in apical third for MAF size #30 was comparable with that of the control group (size #40). Conclusion: Minimal apical enlargement for penetration of irrigants to the apical third of root canal system is #30 size. PMID:26124608

  12. Identification of neuronal and angiogenic growth factors in an in vitro blood-brain barrier model system: Relevance in barrier integrity and tight junction formation and complexity.

    Science.gov (United States)

    Freese, Christian; Hanada, Sanshiro; Fallier-Becker, Petra; Kirkpatrick, C James; Unger, Ronald E

    2017-05-01

    We previously demonstrated that the co-cultivation of endothelial cells with neural cells resulted in an improved integrity of the in vitro blood-brain barrier (BBB), and that this model could be useful to evaluate the transport properties of potential central nervous system disease drugs through the microvascular brain endothelial. In this study we have used real-time PCR, fluorescent microscopy, protein arrays and enzyme-linked immunosorbent assays to determine which neural- and endothelial cell-derived factors are produced in the co-culture and improve the integrity of the BBB. In addition, a further improvement of the BBB integrity was achieved by adjusting serum concentrations and growth factors or by the addition of brain pericytes. Under specific conditions expression of angiogenic, angiostatic and neurotrophic factors such as endostatin, pigment epithelium derived factor (PEDF/serpins-F1), tissue inhibitor of metalloproteinases (TIMP-1), and vascular endothelial cell growth factor (VEGF) closely mimicked the in vivo situation. Freeze-fracture analysis of these cultures demonstrated the quality and organization of the endothelial tight junction structures and their association to the two different lipidic leaflets of the membrane. Finally, a multi-cell culture model of the BBB with a transendothelial electrical resistance up to 371 (±15) Ω×cm(2) was developed, which may be useful for preliminary screening of drug transport across the BBB and to evaluate cellular crosstalk of cells involved in the neurovascular unit.

  13. Multimodality imaging in apical hypertrophic cardiomyopathy

    Institute of Scientific and Technical Information of China (English)

    Rosario; Parisi; Francesca; Mirabella; Gioel; Gabrio; Secco; Rossella; Fattori

    2014-01-01

    Apical hypertrophic cardiomyopathy(AHCM) is a relatively rare morphologic variant of HCM in which the hypertrophy of myocardium is localized to the left ventricular apex. Symptoms of AHCM might vary from none to others mimic coronary artery disease including acute coronary syndrome, thus resulting in inappropriate hospitalization. Transthoracic echocardiography is the firstline imaging technique for the diagnosis of hypertrophic cardiomyopathies. However, when the hypertrophy of the myocardium is localized in the ventricular apex might results in missed diagnosis. Aim of this paper is to review the different imaging techniques used for the diagnosis of AHCM and their role in the detection and comprehension of this uncommon disease.

  14. Two new septate junctions in the phylum Coelenterata.

    Science.gov (United States)

    Green, C R; Flower, N E

    1980-04-01

    Freeze-fracture of fixed and unfixed tissue, lanthanum tracer and conventional thin-section studies have revealed 2 new types of septate junction in the class Anthozoa, phylum Coelenterata. These new junctions have the 15-18-nm intercellular spacing of all other described septate junctions and are found around the apical circumference of cells lining a lumen or outside edge. However, in freeze-fracture replicas and tangential views of lanthanum-impregnated tissue, they are seen to be quite different from other known septate junction types. One of the new junctions is found in endothelial tissue such as that lining the gut or the inside of the tentacles. In tangential view it is seen to consist of relatively short, straight, double septa, again with lateral projections. In feeeze-fracture of unfixed tissue, the junction consists of double rows of particles on the P face, the particles of one row being rounded, those of the other being elongated at right angles to the line of the septum. This dichotomy in particle size is unexpected, as the 2 halves of the septa as seen in tangential view are symmetrical. In freeze-fracture of fixed material the particle arrays remain on the P face and appear similar to those of unfixed material, but never as clear. In fixed tissue, some distortion had occurred and in extreme cases septa appear as a single broad jumbled row of particles. In this double septa junction, the rows of particles seen in freeze-fracture are occasionally seen to anastomose with a septum dividing into 2 and a third row of particles aligning with the 2 new septa to form their double particle rows. In both fixed and unfixed tissues, the E face of the junction consists of wide, shallow grooves. The second of the new junctions occurs in epithelial tissue, such as around the outer edge of sea-anemone tentacles, and consists of long wavy septa with lateral projections. In views where these projections appear longest, they arise predominantly from one side of the

  15. Endoplasmic reticulum-plasma membrane junctions: structure, function and dynamics.

    Science.gov (United States)

    Okeke, Emmanuel; Dingsdale, Hayley; Parker, Tony; Voronina, Svetlana; Tepikin, Alexei V

    2016-06-01

    Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are contact sites between the ER and the PM; the distance between the two organelles in the junctions is below 40 nm and the membranes are connected by protein tethers. A number of molecular tools and technical approaches have been recently developed to visualise, modify and characterise properties of ER-PM junctions. The junctions serve as the platforms for lipid exchange between the organelles and for cell signalling, notably Ca(2+) and cAMP signalling. Vice versa, signalling events regulate the development and properties of the junctions. Two Ca(2+) -dependent mechanisms of de novo formation of ER-PM junctions have been recently described and characterised. The junction-forming proteins and lipids are currently the focus of vigorous investigation. Junctions can be relatively short-lived and simple structures, forming and dissolving on the time scale of a few minutes. However, complex, sophisticated and multifunctional ER-PM junctions, capable of attracting numerous protein residents and other cellular organelles, have been described in some cell types. The road from simplicity to complexity, i.e. the transformation from simple 'nascent' ER-PM junctions to advanced stable multiorganellar complexes, is likely to become an attractive research avenue for current and future junctologists. Another area of considerable research interest is the downstream cellular processes that can be activated by specific local signalling events in the ER-PM junctions. Studies of the cell physiology and indeed pathophysiology of ER-PM junctions have already produced some surprising discoveries, likely to expand with advances in our understanding of these remarkable organellar contact sites. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  16. F-Theory Description of 3-String Junction

    Institute of Scientific and Technical Information of China (English)

    YANGFu-Zhong

    2003-01-01

    The geometrical description of BPS 3-string junction in the F-theory background is given by lifting a string junction in lib into F-theory and constructing a holomorphic curve in K3 with respect to a special complex structure of K3. The holomorphic curve is fibration of 1-cycles of the elliptic fiber over the geodesic string junction. The F-theory picture in this paper provides a unifying description of both string and string junction, and is advantageous over their M-theory picture.

  17. F-Theory Description of 3-String Junction

    Institute of Scientific and Technical Information of China (English)

    YANG Fu-Zhong

    2003-01-01

    The geometrical description of BPS 3-string junction in the F-theory background is given by lifting a string junction in IIB into F-theory and constructing a holomorphic curve in K3 with respect to a special complex structure of K3. The holomorphic curve is fibration of 1-cycles of the elliptic fiber over the geodesic string junction. The F-theory picture in this paper provides a unifying description of both string and string junction, and is advantageous over their M-theory picture.

  18. Equivalent Josephson junctions

    Science.gov (United States)

    Boyadjiev, T. L.; Semerdjieva, E. G.; Shukrinov, Yu. M.

    2008-01-01

    The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt-or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is adequate to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flow. This fact may explain the improvement of the spectra of microwave radiation noted in the literature.

  19. Intercellular junctions of the hen parathyroid gland. A freeze-fracture study.

    Science.gov (United States)

    Setoguti, T; Inoue, Y; Suematsu, T

    1982-01-01

    The fine structure of the intercellular junctions of the hen parathyroid gland was studied using freeze-fracture replicas and thin sections. In the conventional thin sections, desmosomes, intermediate junctions (maculae adherentes) and gap junctions were observed, and in the lanthanum-fixed sections, tight junctions (maculae occludentes) were demonstrated as well. In the freeze-fracture replicas, desmosomes, gap junctions, tight junctions and combination forms of gap and tight junctions occurred, but intermediate junctions were not identified. Junctional complexes (zonulae occludentes) were not encountered in any preparations. The gap junctions varied in size and shape; they ranged from irregularly shaped, minute assemblages of particles to large aggregations of a round or elliptic outline. Both the tight junctions and the combination forms of gap and tight junctions also exhibited a variety of shape and dimension, and, depending on the form of the tight junctional strands, they were classified into three types: type I consisted of a simple line of strands; type II consisted of a closed network of strands; and type III consisted of an open network of strands. The combination forms were more numerous than the typical tight junctions. The possible significance of these junctions is discussed in relation to the function of the parathyroid parenchymal cell. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 PMID:7174510

  20. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  1. Cell junction proteins within the cochlea:A review of recent research

    Institute of Scientific and Technical Information of China (English)

    Bo Wang; Bohua Hu; Shiming Yang

    2015-01-01

    Cell—cell junctions in the cochlea are highly complex and well organized. The role of these junctions is to maintain structural and functional integrity of the cochlea. In this review, we describe classification of cell junction-associated proteins identified within the cochlea and provide a brief overview of the function of these proteins in adherent junctions, gap junctions and tight junctions. Copyright © 2016, PLA General Hospital Department of Otolaryngology Head and Neck Surgery. Production and hosting by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

  2. Understanding the shoot apical meristem regulation: a study of the phytohormones, auxin and cytokinin, in rice.

    Science.gov (United States)

    Azizi, P; Rafii, M Y; Maziah, M; Abdullah, S N A; Hanafi, M M; Latif, M A; Rashid, A A; Sahebi, M

    2015-02-01

    Auxin and cytokinin regulate different critical processes involved in plant growth and environmental feedbacks. These plant hormones act either synergistically or antagonistically to control the organisation, formation and maintenance of meristem. Meristem cells can be divided to generate new tissues and organs at the locations of plant postembryonic development. The aboveground plant organs are created by the shoot apical meristem (SAM). It has been proposed that the phytohormone, cytokinin, plays a positive role in the shoot meristem function, promotes cell expansion and promotes an increasing size of the meristem in Arabidopsis, whereas it has the reverse effects in the root apical meristem (RAM). Over the last few decades, it has been believed that the apically derived auxin suppresses the shoot branching by inactivating the axillary buds. However, it has recently become clear that the mechanism of action of auxinis indirect and multifaceted. In higher plants, the regulatory mechanisms of the SAM formation and organ separation are mostly unknown. This study reviews the effects and functions of cytokinin and auxin at the shoot apical meristem. This study also highlights the merger of the transcription factor activity with the actions of cytokinin/auxin and their complex interactions with the shoot meristem in rice. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  3. Apical-dominant particle swarm optimization

    Institute of Scientific and Technical Information of China (English)

    Zhihua Cui; Xingjuan Cai; Jianchao Zeng; Guoji Sun

    2008-01-01

    Particle swarm optimization (PSO) is a new stochastic population-based search methodology by simulating the animal social behaviors such as birds flocking and fish schooling.Many improvements have been proposed within the framework of this biological assumption.However,in this paper,the search pattern of PSO is used to model the branch growth process of natural plants.It provides a different poten-tial manner from artificial plant.To illustrate the effectiveness of this new model,apical dominance phenomenon is introduced to construct a novel variant by emphasizing the influence of the phototaxis.In this improvement,the population is divided into three different kinds of buds associated with their performances.Furthermore,a mutation strategy is applied to enhance the ability escaping from a local optimum.Sim-ulation results demonstrate good performance of the new method when solving high-dimensional multi-modal problems.

  4. The EhCPADH112 Complex of Entamoeba histolytica Interacts with Tight Junction Proteins Occludin and Claudin-1 to Produce Epithelial Damage

    OpenAIRE

    Abigail Betanzos; Rosario Javier-Reyna; Guillermina García-Rivera; Cecilia Bañuelos; Lorenza González-Mariscal; Michael Schnoor; Esther Orozco

    2013-01-01

    Entamoeba histolytica, the protozoan responsible for human amoebiasis, causes between 30,000 and 100,000 deaths per year worldwide. Amoebiasis is characterized by intestinal epithelial damage provoking severe diarrhea. However, the molecular mechanisms by which this protozoan causes epithelial damage are poorly understood. Here, we studied the initial molecular interactions between the E. histolytica EhCPADH112 virulence complex and epithelial MDCK and Caco-2 cells. By confocal microscopy, we...

  5. Apical Hypertrophic Cardiomyopathy in Association with PulmonaryArtery Hypertension

    Directory of Open Access Journals (Sweden)

    Mehdi Peighambari

    2012-09-01

    Full Text Available Apical Hypertrophic Cardiomyopathy is an uncommon condition constituting 1% -2% of the cases with Hypertrophic Cardiomyopathy (HCM diagnosis. We interestingly report two patients with apical hypertrophic cardiomyopathy in association with significant pulmonary artery hypertension without any other underlying reason for pulmonary hypertension. The patients were assessed by echocardiography, cardiac catheterization and pulmonary function parameters study.

  6. Reversible transient apical ballooning syndrome with coronary lesions

    Institute of Scientific and Technical Information of China (English)

    Yunshan Cao; Min Zhang; Xiang Li; Ping Xie; Lynn Cronin

    2009-01-01

    Transient apical ballooning syndrome(Tako-Tsubo syndrome or ampulla cardiomyopathy) occurs predominantly in women over 60 years of age with a history of recent physical or psychological stress. We present a case of a male patient with reversible transient apical ballooning syndrome with significant coronary lesions and other ECG changes that did not explain the clinical symptoms.

  7. Apical Ballooning Syndrome: A Complication of Dual Chamber Pacemaker Implantation

    Science.gov (United States)

    Abu Sham'a, Raed A. H; Asher, Elad; Luria, David; Berger, Michael; Glikson, Michael

    2009-01-01

    Apical ballooning is a cardiac syndrome (Takotsubo Cardiomyopathy) described as a typical form of acute transient left ventricular dysfunction. While its onset has often been associated with emotionally or physically stressful situations, it has an overall favorable prognosis. We describe here a case of transient apical ballooning following permanent pacemaker implantation. PMID:19652736

  8. Apical entry channels in calcium-transporting epithelia.

    Science.gov (United States)

    Peng, Ji-Bin; Brown, Edward M; Hediger, Matthias A

    2003-08-01

    The identification of the apical calcium channels CaT1 and ECaC revealed the key molecular mechanisms underlying apical calcium entry in calcium-transporting epithelia. These channels are regulated directly or indirectly by vitamin D and dietary calcium and undergo feedback control by intracellular calcium, suggesting their rate-limiting roles in transcellular calcium transport.

  9. In vitro study of the apical microleakage with resilon root canal filling using different final endodontic irrigants

    Science.gov (United States)

    Lahor-Soler, Eduard; Brunet-Llobet, Lluís; Farré, Magí; Pumarola, Josep

    2015-01-01

    Background Endodontic microleakage or microfiltration refers to the percolation of fluids and micro-organisms at the interface of the obturation material and the walls of the root canal system. The aim of this in vitro study was to compare apical microfiltration of Resilon root canal filling by employing three different final irrigant solutions. Material and Methods 128 single-rooted teeth were employed. The crowns were sectioned horizontally at the cemento-enamel junction and instrumented with 5.25% sodium hypochlorite (NaOCl) and 17% EDTA gel to obtain an instrumented 040 apical caliber. An intermediate irrigation was performed with distilled water. The roots were then randomly assigned to three experimental groups with three different final irrigants: (A) 20% citric acid (CA); (B) 2% chlorhexidine digluconate (CHX); and (C) 5.25% NaOCl, plus two control groups (positive and negative). They were then dried, obturated with RealSeal™, and cleared by Robertson’s technique. Apical microleakage was measured by the dye penetration method and assessed with a 4.5x stereomicroscope. Data were statistically analyzed by one way ANOVA and post hoc analysis for multiple comparisons. Results Mean and standard deviations for apical microleakage were: 2% CHX (0.24 mm ± 0.22), 20% CA (0.25 mm ± 0.20), and 5.25% NaOCl (0.87 mm ± 0.32). Significant differences were reported among the group irrigated with NaOCl, CHX and CA (Pirrigation was performed with NaOCl whilst lower rates were reported for CHX and CA. Key words:Apical filtration, endodontic irrigation, resin-based sealers, adhesion, root canal filling. PMID:26155335

  10. Efficacy of Biodentine as an Apical Plug in Nonvital Permanent Teeth with Open Apices: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Mehmet Bani

    2015-01-01

    Full Text Available The aim of this study was to evaluate the apical microleakage of Biodentine and MTA orthograde apical plugs and to compare the effect of thickness of these biomaterials on their sealing ability. A total of eighty maxillary anterior teeth were used. The apices were removed by cutting with a diamond disc (Jota, Germany 2 mm from the apical root end in an attempt to standardize the working length of all specimens to 15 ± 1 mm. Both materials were placed in 1–4 mm thickness as apical plugs root canal. Root canal leakage was evaluated by the fluid filtration technique. One-way ANOVA was used in order to determine normality of dispersal distribution of parameters; thereafter, results were analyzed by Kolmogorov-Smirnov test. Overall, between microleakage values of MTA and Biodentine regardless of apical plug thickness, no difference was observed. In terms of plug thickness, a statistically significant difference was observed between the subgroups of MTA and Biodentine (p<0.05. The apical sealing ability of Biodentine was comparable to MTA at any apical plug thickness.

  11. Morphology of bacterial flora in root canals associated with apical abscesses

    Institute of Scientific and Technical Information of China (English)

    Guo Huijie; Gao Chengzhi; Zhang Chengfei; Zheng Shuying; Yue Lin

    2014-01-01

    Background Apical abscess is an inflammatory process in the peri-radicular tissues caused by biofllms in the necrotic root canal systems.Therefore,a comprehensive analysis of the bacterial colonization is required for a better understanding of the pathogenesis.This study aimed to investigate the patterns of bacterial infection of root canals of teeth with apical abscesses and to determine whether histological and microbiological findings correlated with clinical conditions.Methods Eighteen samples from 18 teeth with apical pathological lesions were analyzed.Nine patients with acute apical abscesses experienced severe pain,and nine patients were asymptomatic with a sinus tract.After extraction,each affected root was divided into two halves.One half was processed for histobacteriologic analysis and examined using light microscopy,and the other half was analyzed using scanning electron microscopy (SEM) to determine the patterns of microbial colonization of the root canals.Results The appearance of each sample subjected to SEM was consistent with the histobacteriologic findings despite the presence or absence of clinical symptoms.Intraradicular biofilms comprising cocci,rods,and/or filaments of amorphous materials were observed in the apical third of the main root canals in all samples.The bacterial biofilms covering the main root canal walls also penetrated the dentinal tubules to varying depths.The morphologies of biofilms varied,and a unique pattern of intraradicular infection was not identified.Conclusion Intraradicular infections formed complex and variable multispecies biofilms and their presence did not correlate with clinical symptoms.

  12. Delay enhancement patterns in apical hypertrophic cardiomyopathy by phase-sensitive inversion recovery sequence

    Institute of Scientific and Technical Information of China (English)

    Zi-Yi Guo; Jing Chen; Qi-Zhou Liang; Hai-Yan Liao; Shui-Xi Fu; Qian-Yu Tang; Cai-Xiang Chen; Xiang-Jun Han; Feng Gao

    2012-01-01

    Objective:Late gadolinium enhancement (LGE) patterns of cardiovascular magnetic resonance (CMR) relying on PSIR (phase-sensitive inversion recovery sequence) techniques had been used to determine the characteristics of LGE in apical hypertrophic cardiomyopathy (ApHCM). Methods:Forty patients pure ApHCM [age, (60.2±10.4) years, 31 men] were enrolled. LGE images were acquired using PSIR, and analyzed using a 17-segment model. Summing the LGE areas in all short axis slices yielded the total volume of late enhancement, which was subsequently presented as a proportion of total LV myocardium (%LGE). Results:Mean maximal apical wall thickness was (17.9±2.3) mm, and mean left ventricular (LV) ejection fraction was (67.7±8.0)%. LGE was detected in 130 segments of 30 patients (75.0%), occupying (4.9±5.5)%of LV myocardium. LGE was mainly detected at the junction between left and right ventricles in 12 (30%) and at the apex in 28 (70%), although LGE-positive areas were widely distributed, and not limited to the apex. Focal LGE at the non-hypertrophic LV segments was found in some ApHCM patients, even without LGE of hypertrophied apical segments. Conclusions: LGE was frequently observed not only in the thickened apex of the heart but also in other LV segments, irrespective of the presence or absence of hypertrophy. The simple presence of LGE on CMR was not representative of adverse prognosis in this population.

  13. Maxillary first premolars: I. Morphology of the apical constriction

    Institute of Scientific and Technical Information of China (English)

    Daming Wu; Younong Wu; Ming Hu

    2009-01-01

    Objective: To investigated the apical constriction morphology of maxillary first premolars in the Chinese population. Methods: Eighty recently extracted human maxillary first premolars from a native Chinese population were used. The number and shape of apical constrictions were recorded under a dental operating microscope (DOM) at 12.5X2.5 magnification. After access preparation, a new K-file was inserted into the canal until the tip of the file was just seen at the apical constriction under the DOM. The teeth with files in the canals were X-rayed from a mesiodistal direction using a direct digital radiography (DDR) system, and the distance between the file tip and the center of radiographic apex was directly measured from the computer screen using DDR measurement software. Results: The percentage of teeth with an apical constriction was 78.5% (102/130). The most common apical constriction shapes were oval (55.9%) and round (35.3%). The mean distance between the apical constriction and the anatomical tip of the root was 0.61 mm, and 84.3% (86/102) were within 1 mm. Conclusion: The most common shape of an apical constriction was oval or round, and the distance to the apex was mostly within 1 mm, indicating that root canal therapy should stop 1 mm from the radiographic apex.

  14. Bony change of apical lesion healing process using fractal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ji Min; Park, Hyok; Jeong, Ho Gul; Kim, Kee Deog; Park, Chang Seo [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2005-06-15

    To investigate the change of bone healing process after endodontic treatment of the tooth with an apical lesion by fractal analysis. Radiographic images of 35 teeth from 33 patients taken on first diagnosis, 6 months, and 1 year after endodontic treatment were selected. Radiographic images were taken by JUPITER computerized Dental X-ray System. Fractal dimensions were calculated three times at each area by Scion Image PC program. Rectangular region of interest (30 x 30) were selected at apical lesion and normal apex of each image. The fractal dimension at apical lesion of first diagnosis (L{sub 0}) is 0.940 {+-} 0.361 and that of normal area (N{sub 0}) is 1.186 {+-} 0.727 (p<0.05). Fractal dimension at apical lesion of 6 months after endodontic treatment (L{sub 1}) is 1.076 {+-} 0.069 and that of normal area (N{sub 1}) is 1.192 {+-} 0.055 (p<0.05). Fractal dimension at apical lesion of 1 year after endodontic treatment (L{sub 2}) is 1.163 {+-} 0.074 and that of normal area (N{sub 2}) is 1.225 {+-} 0.079 (p<0.05). After endodontic treatment, the fractal dimensions at each apical lesions depending on time showed statistically significant difference. And there are statistically significant different between normal area and apical lesion on first diagnosis, 6 months after, 1 year after. But the differences were grow smaller as time flows. The evaluation of the prognosis after the endodontic treatment of the apical lesion was estimated by bone regeneration in apical region. Fractal analysis was attempted to overcome the limit of subjective reading, and as a result the change of the bone during the healing process was able to be detected objectively and quantitatively.

  15. Urothelial Defects from Targeted Inactivation of Exocyst Sec10 in Mice Cause Ureteropelvic Junction Obstructions.

    Directory of Open Access Journals (Sweden)

    Ben Fogelgren

    Full Text Available Most cases of congenital obstructive nephropathy are the result of ureteropelvic junction obstructions, and despite their high prevalence, we have a poor understanding of their etiology and scarcity of genetic models. The eight-protein exocyst complex regulates polarized exocytosis of intracellular vesicles in a large variety of cell types. Here we report generation of a conditional knockout mouse for Sec10, a central component of the exocyst, which is the first conditional allele for any exocyst gene. Inactivation of Sec10 in ureteric bud-derived cells using Ksp1.3-Cre mice resulted in severe bilateral hydronephrosis and complete anuria in newborns, with death occurring 6-14 hours after birth. Sec10 FL/FL;Ksp-Cre embryos developed ureteropelvic junction obstructions between E17.5 and E18.5 as a result of degeneration of the urothelium and subsequent overgrowth by surrounding mesenchymal cells. The urothelial cell layer that lines the urinary tract must maintain a hydrophobic luminal barrier again urine while remaining highly stretchable. This barrier is largely established by production of uroplakin proteins that are transported to the apical surface to establish large plaques. By E16.5, Sec10 FL/FL;Ksp-Cre ureter and pelvic urothelium showed decreased uroplakin-3 protein at the luminal surface, and complete absence of uroplakin-3 by E17.5. Affected urothelium at the UPJ showed irregular barriers that exposed the smooth muscle layer to urine, suggesting this may trigger the surrounding mesenchymal cells to overgrow the lumen. Findings from this novel mouse model show Sec10 is critical for the development of the urothelium in ureters, and provides experimental evidence that failure of this urothelial barrier may contribute to human congenital urinary tract obstructions.

  16. Urothelial Defects from Targeted Inactivation of Exocyst Sec10 in Mice Cause Ureteropelvic Junction Obstructions.

    Science.gov (United States)

    Fogelgren, Ben; Polgar, Noemi; Lui, Vanessa H; Lee, Amanda J; Tamashiro, Kadee-Kalia A; Napoli, Josephine Andrea; Walton, Chad B; Zuo, Xiaofeng; Lipschutz, Joshua H

    2015-01-01

    Most cases of congenital obstructive nephropathy are the result of ureteropelvic junction obstructions, and despite their high prevalence, we have a poor understanding of their etiology and scarcity of genetic models. The eight-protein exocyst complex regulates polarized exocytosis of intracellular vesicles in a large variety of cell types. Here we report generation of a conditional knockout mouse for Sec10, a central component of the exocyst, which is the first conditional allele for any exocyst gene. Inactivation of Sec10 in ureteric bud-derived cells using Ksp1.3-Cre mice resulted in severe bilateral hydronephrosis and complete anuria in newborns, with death occurring 6-14 hours after birth. Sec10 FL/FL;Ksp-Cre embryos developed ureteropelvic junction obstructions between E17.5 and E18.5 as a result of degeneration of the urothelium and subsequent overgrowth by surrounding mesenchymal cells. The urothelial cell layer that lines the urinary tract must maintain a hydrophobic luminal barrier again urine while remaining highly stretchable. This barrier is largely established by production of uroplakin proteins that are transported to the apical surface to establish large plaques. By E16.5, Sec10 FL/FL;Ksp-Cre ureter and pelvic urothelium showed decreased uroplakin-3 protein at the luminal surface, and complete absence of uroplakin-3 by E17.5. Affected urothelium at the UPJ showed irregular barriers that exposed the smooth muscle layer to urine, suggesting this may trigger the surrounding mesenchymal cells to overgrow the lumen. Findings from this novel mouse model show Sec10 is critical for the development of the urothelium in ureters, and provides experimental evidence that failure of this urothelial barrier may contribute to human congenital urinary tract obstructions.

  17. The human myotendinous junction

    DEFF Research Database (Denmark)

    Knudsen, A B; Larsen, M; Mackey, Abigail

    2015-01-01

    The myotendinous junction (MTJ) is a specialized structure in the musculotendinous system, where force is transmitted from muscle to tendon. Animal models have shown that the MTJ takes form of tendon finger-like processes merging with muscle tissue. The human MTJ is largely unknown and has never ...

  18. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: thierry.melin@isen.iemn.univ-lille1.fr [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-11-28

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  19. Junction trees of general graphs

    Institute of Scientific and Technical Information of China (English)

    Xiaofei WANG; Jianhua GUO

    2008-01-01

    In this paper,we study the maximal prime subgraphs and their corresponding structure for any undirected graph.We introduce the notion of junction trees and investigate their structural characteristics,including junction properties,induced-subtree properties,running-intersection properties and maximum-weight spanning tree properties.Furthermore,the characters of leaves and edges on junction trees are discussed.

  20. Dichotomous branching: the plant form and integrity upon the apical meristem bifurcation

    Directory of Open Access Journals (Sweden)

    Edyta M. Gola

    2014-06-01

    Full Text Available The division of the apical meristem into two independently functioning axes is defined as dichotomous branching. This type of branching typically occurs in non-vascular and non-seed vascular plants, whereas in seed plants it presents a primary growth form only in several taxa. Dichotomy is a complex process, which requires a re-organization of the meristem structure and causes changes in the apex geometry and activity. However, the mechanisms governing the repetitive apex divisions are hardly known. Here, an overview of dichotomous branching is presented, occurring in structurally different apices of phylogenetically distant plants, and in various organs (e.g. shoots, roots, rhizophores. Additionally, morphogenetic effects of dichotomy are reviewed, including its impact on organogenesis and mechanical constraints. At the end, the hormonal and genetic regulation of the dichotomous branching is discussed.

  1. Genome-wide analyses for dissecting gene regulatory networks in the shoot apical meristem.

    Science.gov (United States)

    Bustamante, Mariana; Matus, José Tomás; Riechmann, José Luis

    2016-03-01

    Shoot apical meristem activity is controlled by complex regulatory networks in which components such as transcription factors, miRNAs, small peptides, hormones, enzymes and epigenetic marks all participate. Many key genes that determine the inherent characteristics of the shoot apical meristem have been identified through genetic approaches. Recent advances in genome-wide studies generating extensive transcriptomic and DNA-binding datasets have increased our understanding of the interactions within the regulatory networks that control the activity of the meristem, identifying new regulators and uncovering connections between previously unlinked network components. In this review, we focus on recent studies that illustrate the contribution of whole genome analyses to understand meristem function. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  2. Efficacy of Biodentine as an Apical Plug in Nonvital Permanent Teeth with Open Apices: An In Vitro Study.

    Science.gov (United States)

    Bani, Mehmet; Sungurtekin-Ekçi, Elif; Odabaş, Mesut Enes

    2015-01-01

    The aim of this study was to evaluate the apical microleakage of Biodentine and MTA orthograde apical plugs and to compare the effect of thickness of these biomaterials on their sealing ability. A total of eighty maxillary anterior teeth were used. The apices were removed by cutting with a diamond disc (Jota, Germany) 2 mm from the apical root end in an attempt to standardize the working length of all specimens to 15 ± 1 mm. Both materials were placed in 1-4 mm thickness as apical plugs root canal. Root canal leakage was evaluated by the fluid filtration technique. One-way ANOVA was used in order to determine normality of dispersal distribution of parameters; thereafter, results were analyzed by Kolmogorov-Smirnov test. Overall, between microleakage values of MTA and Biodentine regardless of apical plug thickness, no difference was observed. In terms of plug thickness, a statistically significant difference was observed between the subgroups of MTA and Biodentine (p Biodentine was comparable to MTA at any apical plug thickness.

  3. Irrigation dynamics associated with positive pressure, apical negative pressure and passive ultrasonic irrigations: a computational fluid dynamics analysis.

    Science.gov (United States)

    Chen, José Enrique; Nurbakhsh, Babak; Layton, Gillian; Bussmann, Markus; Kishen, Anil

    2014-08-01

    Complexities in root canal anatomy and surface adherent biofilm structures remain as challenges in endodontic disinfection. The ability of an irrigant to penetrate into the apical region of a canal, along with its interaction with the root canal walls, will aid in endodontic disinfection. The aim of this study was to qualitatively examine the irrigation dynamics of syringe irrigation with different needle tip designs (open-ended and closed-ended), apical negative pressure irrigation with the EndoVac® system, and passive ultrasonic-assisted irrigation, using a computational fluid dynamics model. Syringe-based irrigation with a side-vented needle showed a higher wall shear stress than the open-ended but was localised to a small region of the canal wall. The apical negative pressure mode of irrigation generated the lowest wall shear stress, while the passive-ultrasonic irrigation group showed the highest wall shear stress along with the greatest magnitude of velocity.

  4. Cdc42-dependent Modulation of Tight Junctions and Membrane Protein Traffic in Polarized Madin-Darby Canine Kidney Cells

    Science.gov (United States)

    Rojas, Raul; Ruiz, Wily G.; Leung, Som-Ming; Jou, Tzuu-Shuh; Apodaca, Gerard

    2001-01-01

    Polarized epithelial cells maintain the asymmetric composition of their apical and basolateral membrane domains by at least two different processes. These include the regulated trafficking of macromolecules from the biosynthetic and endocytic pathway to the appropriate membrane domain and the ability of the tight junction to prevent free mixing of membrane domain-specific proteins and lipids. Cdc42, a Rho family GTPase, is known to govern cellular polarity and membrane traffic in several cell types. We examined whether this protein regulated tight junction function in Madin-Darby canine kidney cells and pathways that direct proteins to the apical and basolateral surface of these cells. We used Madin-Darby canine kidney cells that expressed dominant-active or dominant-negative mutants of Cdc42 under the control of a tetracycline-repressible system. Here we report that expression of dominant-active Cdc42V12 or dominant-negative Cdc42N17 altered tight junction function. Expression of Cdc42V12 slowed endocytic and biosynthetic traffic, and expression of Cdc42N17 slowed apical endocytosis and basolateral to apical transcytosis but stimulated biosynthetic traffic. These results indicate that Cdc42 may modulate multiple cellular pathways required for the maintenance of epithelial cell polarity. PMID:11514615

  5. Overdamped Josephson junctions for digital applications

    Energy Technology Data Exchange (ETDEWEB)

    Febvre, P., E-mail: Pascal.Febvre@univ-savoie.fr [University of Savoie, IMEP-LAHC – CNRS UMR5130, 73376 Le Bourget du Lac (France); De Leo, N.; Fretto, M.; Sosso, A. [I.N.Ri.M., Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino (Italy); Belogolovskii, M. [Donetsk Institute for Physics and Engineering, 72 R. Luxemburg str., 83114 Donetsk (Ukraine); Collot, R. [University of Savoie, IMEP-LAHC – CNRS UMR5130, 73376 Le Bourget du Lac (France); Lacquaniti, V. [I.N.Ri.M., Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Torino (Italy)

    2013-01-15

    Highlights: ► Properties of self-shunted sub-micron Nb/Al–AlO{sub x}/Nb SNIS junctions are studied. ► 1–100 kA/cm{sup 2} current densities and 0.1–0.7 mV critical voltages are obtained. ► The critical voltage-vs-temperature behavior of SNIS junctions is discussed. ► Numerical results showing an effect of the aluminum film thickness are presented. ► A Josephson balanced comparator is studied for different temperatures of operation. -- Abstract: An interesting feature of Superconductor–Normal metal–Superconductor Josephson junctions for digital applications is due to their non-hysteretic current–voltage characteristics in a broad temperature range below T{sub c}. This allows to design Single-Flux-Quantum (SFQ) cells without the need of external shunts. Two advantages can be drawn from this property: first the SFQ cells can be more compact which leads to a more integrated solution towards nano-devices and more complex circuits; second the absence of electrical parasitic elements associated with the wiring of resistors external to the Josephson junctions increases the performance of SFQ circuits, in particular regarding the ultimate speed of operation. For this purpose Superconductor–Normal metal–Insulator–Superconductor Nb/Al–AlO{sub x}/Nb Josephson junctions have been recently developed at INRiM with aluminum layer thicknesses between 30 and 100 nm. They exhibit non-hysteretic current–voltage characteristics with I{sub c}R{sub n} values higher than 0.5 mV in a broad temperature range and optimal Stewart McCumber parameters at 4.2 K for RSFQ applications. The main features of obtained SNIS junctions regarding digital applications are presented.

  6. Surgery for women with apical vaginal prolapse.

    Science.gov (United States)

    Maher, Christopher; Feiner, Benjamin; Baessler, Kaven; Christmann-Schmid, Corina; Haya, Nir; Brown, Julie

    2016-10-01

    Apical vaginal prolapse is a descent of the uterus or vaginal vault (post-hysterectomy). Various surgical treatments are available and there are no guidelines to recommend which is the best. To evaluate the safety and efficacy of any surgical intervention compared to another intervention for the management of apical vaginal prolapse. We searched the Cochrane Incontinence Group's Specialised Register of controlled trials, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, ClinicalTrials.gov, WHO ICTRP and handsearching of journals and conference proceedings (searched July 2015) and ClinicalTrials.gov (searched January 2016). We included randomised controlled trials (RCTs). We used Cochrane methods. Our primary outcomes were awareness of prolapse, repeat surgery and recurrent prolapse (any site). We included 30 RCTs (3414 women) comparing surgical procedures for apical vaginal prolapse. Evidence quality ranged from low to moderate. Limitations included imprecision, poor methodological reporting and inconsistency. Vaginal procedures versus sacral colpopexy (six RCTs, n = 583; one to four-year review). Awareness of prolapse was more common after vaginal procedures (risk ratio (RR) 2.11, 95% confidence interval (CI) 1.06 to 4.21, 3 RCTs, n = 277, I(2) = 0%, moderate-quality evidence). If 7% of women are aware of prolapse after sacral colpopexy, 14% (7% to 27%) are likely to be aware after vaginal procedures. Repeat surgery for prolapse was more common after vaginal procedures (RR 2.28, 95% CI 1.20 to 4.32; 4 RCTs, n = 383, I(2) = 0%, moderate-quality evidence). The confidence interval suggests that if 4% of women require repeat prolapse surgery after sacral colpopexy, between 5% and 18% would require it after vaginal procedures.We found no conclusive evidence that vaginal procedures increaserepeat surgery for stress urinary incontinence (SUI) (RR 1.87, 95% CI 0.72 to 4.86; 4 RCTs, n = 395; I(2) = 0%, moderate

  7. Vacuolar processing enzyme activates programmed cell death in the apical meristem inducing loss of apical dominance.

    Science.gov (United States)

    Teper-Bamnolker, Paula; Buskila, Yossi; Belausov, Eduard; Wolf, Dalia; Doron-Faigenboim, Adi; Ben-Dor, Shifra; Van der Hoorn, Renier A L; Lers, Amnon; Eshel, Dani

    2017-10-01

    The potato (Solanum tuberosum L.) tuber is a swollen underground stem that can sprout in an apical dominance (AD) pattern. Bromoethane (BE) induces loss of AD and the accumulation of vegetative vacuolar processing enzyme (S. tuberosum vacuolar processing enzyme [StVPE]) in the tuber apical meristem (TAM). Vacuolar processing enzyme activity, induced by BE, is followed by programmed cell death in the TAM. In this study, we found that the mature StVPE1 (mVPE) protein exhibits specific activity for caspase 1, but not caspase 3 substrates. Optimal activity of mVPE was achieved at acidic pH, consistent with localization of StVPE1 to the vacuole, at the edge of the TAM. Downregulation of StVPE1 by RNA interference resulted in reduced stem branching and retained AD in tubers treated with BE. Overexpression of StVPE1 fused to green fluorescent protein showed enhanced stem branching after BE treatment. Our data suggest that, following stress, induction of StVPE1 in the TAM induces AD loss and stem branching. © 2017 John Wiley & Sons Ltd.

  8. Effect of cytokinins on shoot apical meristem in Nicotiana tabacum

    Directory of Open Access Journals (Sweden)

    Uzelac Branka

    2012-01-01

    Full Text Available Cytokinins are involved in plant cell proliferation leading to plant growth and morphogenesis. The size, activity and maintenance of the shoot apical meristem (SAM are defined by a balanced rate of mitotic cell divisions and functional cell differentiation that are controlled by cytokinins. In order to investigate the effect of exogenous cytokinin on SAM, morpho-anatomical changes in the shoot apices of tobacco treated with benzyladenine (BA were compared to those of untreated control plants.

  9. Hypertrophic cardiomyopathy with mid-ventricular obstruction and apical aneurysm

    Directory of Open Access Journals (Sweden)

    N.D. Oryshchyn

    2016-11-01

    Full Text Available A case report of apical left ventricular aneurysm in patient with hypertrophic cardiomyopathy with mid-ventricular obstruction (diagnosis and surgical treatment is presented. We revealed apical aneurysm and mid-ventricular obstruction during echocardiography and specified anatomical characteristics of aneurysm during computer tomography. There was no evidence of obstructive coronary artery disease during coronary angiography. Taking into consideration multiple cerebral infarcts, aneurysm resection and left ventricular plastics was performed. Electronic microscopy of myocardium confirmed the diagnosis of hypertrophic cardiomyopathy.

  10. Development of apical blebbing in the boar epididymis.

    Directory of Open Access Journals (Sweden)

    Jennifer Hughes

    Full Text Available Microvesicles are of increasing interest in biology as part of normal function of numerous systems; from the immune system (T cell activation to implantation of the embryo (invasion of the trophoblasts and sperm maturation (protein transfer in the epididymis. Yet, the mechanisms involved in the appearance of apical blebbing from healthy cells as part of their normal function remain understudied. Microvesicles are produced via one of two pathways: exocytosis or apical blebbing also termed ectocytosis. This work quantifies the histological appearance of apical blebbing in the porcine epididymis during development and examines the role of endogenous estrogens in regulating this blebbing. Apical blebbing appears at puberty and increases in a linear manner into sexual maturity suggesting that this blebbing is a mature phenotype. Endogenous estrogen levels were reduced with an aromatase inhibitor but such a reduction did not affect apical blebbing in treated animals compared with their vehicle-treated littermates. Epididymal production of apical blebs is a secretion mechanism of functionally mature principal cells regulated by factors other than estradiol.

  11. Haemostatic agents in apical surgery. A systematic review

    Science.gov (United States)

    Clé-Ovejero, Adrià

    2016-01-01

    Background Blood presence in apical surgery can prevent the correct vision of the surgical field, change the physical properties of filling materials and reduce their sealing ability. Objetive To describe which are the most effective and safest haemostatic agents to control bleeding in patients undergoing apical surgery. Material and Methods TWe carried out a systematic review, using Medline and Cochrane Library databases, of human clinical studies published in the last 10 years. Results The agents that proved more effective in bleeding control were calcium sulphate (100%) and collagen plus epinephrine (92.9%) followed by ferric sulphate (60%), gauze packing (30%) and collagen (16.7%). When using aluminium chloride (Expasyl®), over 90% of the apical lesions improved, but this agent seemed to increase swelling. Epinephrine with collagen did not significantly raise either blood pressure or heart rate. Conclusions Despite the use of several haemostatic materials in apical surgery, there is little evidence on their effectiveness and safety. The most effective haemostatic agents were calcium sulphate and epinephrine plus collagen. Epinephrine plus collagen did not seem to significantly raise blood pressure or heart rate during surgery. Aluminium chloride did not increase postoperative pain but could slightly increase postoperative swelling. Randomized clinical trials are needed to assess the haemostatic effectiveness and adverse effects of haemostatic materials in apical surgery. Key words:Haemostasis, apical surgery. PMID:27475689

  12. Holliday junction resolvases.

    Science.gov (United States)

    Wyatt, Haley D M; West, Stephen C

    2014-09-02

    Four-way DNA intermediates, called Holliday junctions (HJs), can form during meiotic and mitotic recombination, and their removal is crucial for chromosome segregation. A group of ubiquitous and highly specialized structure-selective endonucleases catalyze the cleavage of HJs into two disconnected DNA duplexes in a reaction called HJ resolution. These enzymes, called HJ resolvases, have been identified in bacteria and their bacteriophages, archaea, and eukaryotes. In this review, we discuss fundamental aspects of the HJ structure and their interaction with junction-resolving enzymes. This is followed by a brief discussion of the eubacterial RuvABC enzymes, which provide the paradigm for HJ resolvases in other organisms. Finally, we review the biochemical and structural properties of some well-characterized resolvases from archaea, bacteriophage, and eukaryotes. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  13. Wireless Josephson Junction Arrays

    Science.gov (United States)

    Adams, Laura

    2015-03-01

    We report low temperature, microwave transmission measurements on a wireless two- dimensional network of Josephson junction arrays composed of superconductor-insulator -superconductor tunnel junctions. Unlike their biased counterparts, by removing all electrical contacts to the arrays and superfluous microwave components and interconnects in the transmission line, we observe new collective behavior in the transmission spectra. In particular we will show emergent behavior that systematically responds to changes in microwave power at fixed temperature. Likewise we will show the dynamic and collective response of the arrays while tuning the temperature at fixed microwave power. We discuss these spectra in terms of the Berezinskii-Kosterlitz-Thouless phase transition and Shapiro steps. We gratefully acknowledge the support Prof. Steven Anlage at the University of Maryland and Prof. Allen Goldman at the University of Minnesota. Physics and School of Engineering and Applied Sciences.

  14. The gap junction proteome and its relationship to disease.

    Science.gov (United States)

    Laird, Dale W

    2010-02-01

    In recent years our understanding of connexins has advanced from viewing them simply as proteins with a surprisingly short lifespan that form gap junction channels. Connexins are now known to be multifaceted proteins at the core of many multiprotein complexes that link to structural junctional complexes and cytoskeletal elements, and also to the cellular machinery that facilitates their transport, assembly, function and internalization. Collectively, these connexin-binding proteins can be termed the 'gap junction proteome'. The mechanistic understanding of the gap junction proteome with regards to the dynamic life cycle of connexins has grown further in importance in light of the large number of human diseases attributed to connexin gene mutations and regulatory changes in connexin spatial localization and expression levels.

  15. Effect of Calcium Hydroxide, Chlorhexidine Digluconate and Camphorated Monochlorophenol on the Sealing Ability of Biodentine Apical Plug

    Science.gov (United States)

    Srivastava, Harshit; Prasad, Ashwini B; Raisingani, Deepak; Soni, Dileep

    2016-01-01

    Introduction Teeth with immature apex are managed by establishing an apical plug using various materials and techniques. However, the use of previously placed intracanal medicament may affect the sealing ability of permanent filling material used as an apical plug. Aim To evaluate the effect of removal of previously placed Calcium Hydroxide, Chlorhexidine Digluconate and Camphorated Monochlorophenol as an intracanal medicament on the sealing ability of the Biodentine as an apical plug. Materials and Methods A total of 72 recently extracted human permanent teeth with single root were selected and stored in saline at room temperature. The crown portion of each tooth was removed at the level of cemento enamel junction; 14mm root length was taken as standard length. All the roots were submerged in 20% sulphuric acid up to 3 mm from the apex, for four days for root resorption. One sample was cut longitudinally to look for root resorption under stereo microscope. The canal preparation was done; the roots were kept in moist gauze after instrumentation. A total of 71 roots were randomly divided into three groups. GROUP 1:Calcium hydroxide paste, GROUP 2: Chlorhexidine digluconate, GROUP 3: Camphorated Monochlorophenol (CMCP). The medicaments were removed with stainless steel hand files and 0.5% sodium hypochlorite irrigation. After removal of medicament Biodentine was placed in apical third of resorbed roots and the remaining portion of the canals was filled with gutta-percha. All the 71 roots were analysed with fluid filtration method for evaluating microleakage. Results Comparing all the three groups statistically there was no significant difference. The mean values were found more for group 1 followed by group 2 & 3. Conclusion All the groups showed microleakage. Calcium hydroxide showed the maximum microleakage followed by Chlorhexidine digluconate and least with CMCP. PMID:27504409

  16. Effect of apical clearing technique on the treatment outcome of teeth with asymptomatic apical periodontitis: A randomized clinical trial

    Science.gov (United States)

    Mittal, Priya; Logani, Ajay; Shah, Naseem; Pandey, R. M.

    2016-01-01

    Aim: This study aims to compare the periapical healing of teeth with asymptomatic apical periodontitis treated either by conventional apical preparation (CAP) or apical clearing technique (ACT). Materials and Methods: Twenty subjects with bilateral nonvital similar teeth exhibiting comparable periapical index (PAI) score were enrolled and randomly allocated. Group I (CAP, n = 20): Apical preparation three sizes greater (master apical file [MAF]) than the first binding file at the established working length. Group II (ACT, n = 20): Apical preparation three sizes greater than the MAF that was followed by dry reaming. Root canal therapy was accomplished in single-visit for all the teeth. They were pursued radiographically at 3, 6, 9 and 12 months. Pre- and post-treatment PAI scores were compared. To ascertain the proportion of healed teeth between the two groups, McNemar Chi-square test was applied. Results: At 3, 6, and 9 months’ time interval the proportion of healed teeth for Group II (ACT) was greater in comparison to Group I (CAP) (P < 0.05). However, at 12 months follow-up period this difference was not significant (P = 0.08). Conclusion: ACT enhanced the healing kinetics. However, the long-term (12 months) radiographic outcome was similar for either technique. PMID:27656054

  17. Differentiation of Apical Bud Cells in a Newly Developed Apical Bud Transplantation Model Using GFP Transgenic Mice as Donor

    Science.gov (United States)

    Sakagami, Ryuji; Yoshinaga, Yasunori; Okamura, Kazuhiko

    2016-01-01

    Rodent mandibular incisors have a unique anatomical structure that allows teeth to grow throughout the lifetime of the rodent. This report presents a novel transplantation technique for studying the apical bud differentiation of rodent mandibular incisors. Incisal apical end tissue with green fluorescent protein from transgenic mouse was transplanted to wild type mice, and the development of the transplanted cells were immunohistologically observed for 12 weeks after the transplantation. Results indicate that the green fluorescent apical end tissue replaced the original tissue, and cells from the apical bud differentiated and extended toward the incisal edge direction. The immunostaining with podoplanin also showed that the characteristics of the green fluorescent tissue were identical to those of the original. The green fluorescent cells were only found in the labial side of the incisor up to 4 weeks. After 12 weeks, however, they were also found in the lingual side. Here the green fluorescent cementocyte-like cells were only present in the cementum close to the dentin surface. This study suggests that some of the cells that form the cellular cementum come from the apical tissue including the apical bud in rodent incisors. PMID:26978064

  18. Differentiation of Apical Bud Cells in a Newly Developed Apical Bud Transplantation Model Using GFP Transgenic Mice as Donor.

    Directory of Open Access Journals (Sweden)

    Naoki Maruo

    Full Text Available Rodent mandibular incisors have a unique anatomical structure that allows teeth to grow throughout the lifetime of the rodent. This report presents a novel transplantation technique for studying the apical bud differentiation of rodent mandibular incisors. Incisal apical end tissue with green fluorescent protein from transgenic mouse was transplanted to wild type mice, and the development of the transplanted cells were immunohistologically observed for 12 weeks after the transplantation. Results indicate that the green fluorescent apical end tissue replaced the original tissue, and cells from the apical bud differentiated and extended toward the incisal edge direction. The immunostaining with podoplanin also showed that the characteristics of the green fluorescent tissue were identical to those of the original. The green fluorescent cells were only found in the labial side of the incisor up to 4 weeks. After 12 weeks, however, they were also found in the lingual side. Here the green fluorescent cementocyte-like cells were only present in the cementum close to the dentin surface. This study suggests that some of the cells that form the cellular cementum come from the apical tissue including the apical bud in rodent incisors.

  19. Diagnosis and planning in apical surgery: use of cone-beam tomography

    Directory of Open Access Journals (Sweden)

    Regina Karla de Pontes Lima

    2010-10-01

    Full Text Available Introduction and objective: The ability to tridimensionally evaluate pathological and anatomical areas, in apical surgery planning, presents a number of advantages. Cone beam computed tomography (CBCT was developed for dental applications. This paper aims to present a literature review on CBCT, highlighting its advantages over both conventional computed tomography (CT and radiography. Moreover, its clinical applications in apical surgery are discussed. Literature review and conclusion: Unlikely CT, CBCT captures a volume of data in a single 360° rotation, providing benefits such as higher accuracy, better resolution, reduced scanning time and reduced radiation dose. In the maxillofacial region, CBCT has been mainly used in the assessment of dento-alveolar pathology and oral traumatology. CBCT provides a better diagnosis and quantitative information on periodontal bone levels than conventional radiography. It has also been used for patients requiring surgical facial reconstruction, orthognathic surgery, dental implants, and more complex tooth extractions. Besides that, it seems to be a significant tool in modern endodontic practice, presenting useful applications in apical surgery.

  20. Supraventricular tachycardia in a patient with Lown-Ganong-Levine syndrome associated with apical hypertrophic cardiomyopathy.

    Science.gov (United States)

    Hayano, M; Imamura, Y; Tsuruta, M; Inoue, J; Nakashima, H; Fukuyama, K; Eguchi, Y; Tsuji, S; Matsuo, S; Yano, K

    1988-03-01

    Electrophysiologic study of a 55-year-old patient with Lown-Ganong-Levine syndrome associated with apical hypertrophic cardiomyopathy is reported. The patient had a history of recurrent attacks of tachyarrhythmia and his electrocardiogram showed a short P-R interval (0.10 sec) with narrow QRS complex and left ventricular hypertrophy with giant negative T waves. His cineangiogram showed severe apical hypertrophy. An electrophysiologic study was performed. The results of programmed atrial pacing show the existence of the dual A-V nodal pathways. The A-H interval at rapid atrial pacing increased maximally by 103 msec. Atrial stimulation could depolarize parts of the atrium without altering the supraventricular tachycardia. These findings suggested that preferential rapidly conducting A-V nodal and intranodal reentry are the responsible mechanisms in this reciprocating tachycardia. We conclude that the short P-R interval was due to intranodal reentry through the dual A-V nodal pathways. To our knowledge, a case of Lown-Ganong-Levine syndrome with apical hypertrophic cardiomyopathy has not been previously described in the literature.

  1. Five-year longitudinal assessment of the prognosis of apical microsurgery

    DEFF Research Database (Denmark)

    von Arx, Thomas; Jensen, Simon S; Hänni, Stefan

    2012-01-01

    Apical surgery is an important treatment option for teeth with post-treatment apical periodontitis. Knowledge of the long-term prognosis is necessary when weighing apical surgery against alternative treatments. This study assessed the 5-year outcome of apical surgery and its predictors in a cohort...

  2. Scattering form factors for self-assembled network junctions

    Science.gov (United States)

    Foster, T.; Safran, S. A.; Sottmann, T.; Strey, R.

    2007-11-01

    The equilibrium microstructures in microemulsions and other self-assembled systems show complex, connected shapes such as symmetric bicontinuous spongelike structures and asymmetric bicontinuous networks formed by cylinders interconnected at junctions. In microemulsions, these cylinder network microstructures may mediate the structural transition from a spherical or globular phase to the bicontinuous microstructure. To understand the structural and statistical properties of such cylinder network microstructures as measured by scattering experiments, models are needed to extract the real-space structure from the scattering data. In this paper, we calculate the scattering functions appropriate for cylinder network microstructures. We focus on such networks that contain a high density of network junctions that connect the cylindrical elements. In this limit, the network microstructure can be regarded as an assembly of randomly oriented, closed packed network junctions (i.e., the cylinder scattering contributions are neglected). Accordingly, the scattering spectrum of the network microstructure can be calculated as the product of the junction number density, the junction form factor, which describes the scattering from the surface of a single junction, and a structure factor, which describes the local correlations of different junctions due to junction interactions (including their excluded volume). This approach is applied to analyze the scattering data from a bicontinuous microemulsion with equal volumes of water and oil. In a second approach, we included the cylinder scattering contribution in the junction form factor by calculating the scattering intensity of Y junctions to which three rods with spherical cross section are attached. The respective theoretical predictions are compared with results of neutron scattering measurements on a water-in-oil microemulsion with a connected microstructure.

  3. Complexity

    CERN Document Server

    Gershenson, Carlos

    2011-01-01

    The term complexity derives etymologically from the Latin plexus, which means interwoven. Intuitively, this implies that something complex is composed by elements that are difficult to separate. This difficulty arises from the relevant interactions that take place between components. This lack of separability is at odds with the classical scientific method - which has been used since the times of Galileo, Newton, Descartes, and Laplace - and has also influenced philosophy and engineering. In recent decades, the scientific study of complexity and complex systems has proposed a paradigm shift in science and philosophy, proposing novel methods that take into account relevant interactions.

  4. Anatomical variations of the anterior atlanto-dental joint and relations to the apical and alar ligaments in a geriatric population.

    Science.gov (United States)

    Rustagi, Tarush; Iwanaga, Joe; Sardi, Juan P; Alonso, Fernando; Oskouian, Rod J; Tubbs, R Shane

    2017-08-17

    Degenerative changes in the upper cervical spine may be age related degeneration or a pathological process such as rheumatoid arthritis. However, to our knowledge, the relationship between the apical and alar ligaments and these anomalies has not been discussed. We present anatomical variations of the anterior atlanto-dental joint observed during cadaveric dissection of adult craniovertebral junctions, the relationship with the alar and apical ligaments and discuss possible origins and clinical implications. The upper cervical spine including part of the occiput was dissected from cadavers whose mean age at death was 78.9 years-old. The anterior atlanto-dental joint and apical and alar ligaments were observed and any atypical findings were noted. In eleven specimens, seven had a dens corona, three had an os odontoideum and one had a dens aureola, which arose from the upper part of the anterior arch of the atlas. Only four specimens had an apical ligament. The possible etiologies and the clinical applications of these craniovertebral anomalies in a geriatric population should be appreciated by the clinician treating patients with disease in this area or interpreting imaging in the region. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Apical Revascularization after Delayed Tooth Replantation: An Unusual Case

    Directory of Open Access Journals (Sweden)

    Marília Pacífico Lucisano

    2016-01-01

    Full Text Available The aim of this paper is to present the clinical and radiological outcome of the treatment involving a delayed tooth replantation after an avulsed immature permanent incisor, with a follow-up of 1 year and 6 months. An 8-year-old boy was referred after dental trauma that occurred on the previous day. The permanent maxillary right central incisor (tooth 11 had been avulsed. The tooth was hand-held during endodontic therapy and an intracanal medication application with calcium hydroxide-based paste was performed. An apical plug with mineral trioxide aggregate (MTA was introduced into the apical portion of the canal. When the avulsed tooth was replanted with digital pressure, a blood clot had formed within the socket, which moved the MTA apical plug about 2 mm inside of the root canal. These procedures developed apical revascularization, which promoted a successful endodontic outcome, evidenced by apical closure, slight increase in root length, and absence of signs of external root resorption, during a follow-up of 1 year and 6 months.

  6. Characterization of rat apical tissues in different root development stage.

    Science.gov (United States)

    Xu, Lin; Yang, Zhenhua; Jin, Fang; Duan, Yinzhong; Jin, Yan

    2011-10-01

    In this study, we try to compare the histological characteristics and the odontogenic capability of apical tissues (AT) at different root development stages of rat molar teeth. AT of mandibular first molars from 8-day-old, 21-day-old, and 35-day-old Sprague-Dawley rats were selected as being representative of root-initiating, root-forming, and root-completing stages, respectively. Cell counting, flow cytometry assays, alkaline phosphatase activity, alizarin red staining, and reverse transcription polymerase chain reaction were performed to assess the proliferation and mineralization potential of apical tissue cells at different stages of root development in vitro. In vivo transplantation of apical tissue cells combined with ceramic bovine bone was used to characterize the differentiation capacity. It was shown that there was a structurally and functionally dynamic change in the apical tissue of developing tooth root of rats, of which the unique developmental potential will reduce gradually with the ending up of root development. The AT of root-initiating and root-forming stage exhibited much higher proliferation and tissue-regenerative capacity than those of root-completing stage. Our present results indicate that the apical tissue, with the sustainable developmental ability throughout almost the whole process of tooth development, can yet be regarded as a competent candidate source for root/periodontal tissues regeneration.

  7. Apical Revascularization after Delayed Tooth Replantation: An Unusual Case

    Science.gov (United States)

    Nelson-Filho, Paulo; Silva, Lea Assed Bezerra; Silva, Raquel Assed Bezerra; de Carvalho, Fabricio Kitazono; de Queiroz, Alexandra Mussolino

    2016-01-01

    The aim of this paper is to present the clinical and radiological outcome of the treatment involving a delayed tooth replantation after an avulsed immature permanent incisor, with a follow-up of 1 year and 6 months. An 8-year-old boy was referred after dental trauma that occurred on the previous day. The permanent maxillary right central incisor (tooth 11) had been avulsed. The tooth was hand-held during endodontic therapy and an intracanal medication application with calcium hydroxide-based paste was performed. An apical plug with mineral trioxide aggregate (MTA) was introduced into the apical portion of the canal. When the avulsed tooth was replanted with digital pressure, a blood clot had formed within the socket, which moved the MTA apical plug about 2 mm inside of the root canal. These procedures developed apical revascularization, which promoted a successful endodontic outcome, evidenced by apical closure, slight increase in root length, and absence of signs of external root resorption, during a follow-up of 1 year and 6 months. PMID:27882250

  8. [Mineral trioxide aggregate (MTA) a success story in apical surgery].

    Science.gov (United States)

    von Arx, Thomas

    2016-01-01

    The objective of apical surgery is to retain teeth with persistent apical pathosis following orthograde root canal treatment if endodontic non-surgical revision is difficult or associated with risks, or is even declined by the patient. Since the most frequent cause of recurrent apical disease is bacterial reinfection from the (remaining) root canal system, the bacteria-tight root-end filling is the most important step in apical surgery. In the early 1990s, mineral trioxide aggregate (MTA) was developed at the Loma Linda University in California/USA. Preclinical studies clearly showed that MTA has a high sealing capability, a good material stability and an excellent biocompatbility. Multiple experimental studies in animals highlighted the mild tissue reactions observed adjacent to this material. Furthermore, histological analysis of the periapical regions demonstrated a frequent deposition of new cementum not only onto the resection plane (cut dentinal surface), but also directly onto MTA. For these reasons, MTA is considered a bioactive material. In 1997 MTA was cleared for clinical use in patients. Multiple prospective clinical and randomized studies have documented high and constant success rates of MTA-treated teeth in apical surgery. A recently published longitudinal study showed that MTA-treated teeth remained stable over five years; hence the high healed rates documented after one year are maintained during long-term observation.

  9. An induced junction photovoltaic cell

    Science.gov (United States)

    Call, R. L.

    1974-01-01

    Silicon solar cells operating with induced junctions rather than diffused junctions have been fabricated and tested. Induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. Measurements of the response of the inversion layer cell to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. The greater sensitivity occurs because of the shallow junction and the strong electric field at the surface.

  10. Gap-junction-mediated cell-to-cell communication.

    Science.gov (United States)

    Hervé, Jean-Claude; Derangeon, Mickaël

    2013-04-01

    Cells of multicellular organisms need to communicate with each other and have evolved various mechanisms for this purpose, the most direct and quickest of which is through channels that directly connect the cytoplasms of adjacent cells. Such intercellular channels span the two plasma membranes and the intercellular space and result from the docking of two hemichannels. These channels are densely packed into plasma-membrane spatial microdomains termed "gap junctions" and allow cells to exchange ions and small molecules directly. A hemichannel is a hexameric torus of junctional proteins around an aqueous pore. Vertebrates express two families of gap-junction proteins: the well-characterized connexins and the more recently discovered pannexins, the latter being related to invertebrate innexins ("invertebrate connexins"). Some gap-junctional hemichannels also appear to mediate cell-extracellular communication. Communicating junctions play crucial roles in the maintenance of homeostasis, morphogenesis, cell differentiation and growth control in metazoans. Gap-junctional channels are not passive conduits, as previously long regarded, but use "gating" mechanisms to open and close the central pore in response to biological stimuli (e.g. a change in the transjunctional voltage). Their permeability is finely tuned by complex mechanisms that have just begun to be identified. Given their ubiquity and diversity, gap junctions play crucial roles in a plethora of functions and their dysfunctions are involved in a wide range of diseases. However, the exact mechanisms involved remain poorly understood.

  11. Variable conformation of GAP junctions linking bone cells: a transmission electron microscopic study of linear, stacked linear, curvilinear, oval, and annular junctions.

    Science.gov (United States)

    Shapiro, F

    1997-10-01

    There is a marked variability in the conformation of bone cell gap junctions in newborn murine cortical bone as defined by transmission electron microscopy (TEM). Studies were done in newborn BALB/c mouse and Sprague-Dawley rat femurs and tibias. Femoral and tibial cortices were dissected into 1 mm3 fragments and prepared in standardized fashion using modified Karnovsky fixation, 7.5% EDTA decalcification, 1% osmium tetroxide-sym collidine buffer with 1% lanthanum nitrate postfixation, Epon resin, 60 nm sections, lead citrate/uranyl acetate staining, and examination at 60 kV. Previous TEM descriptions of bone junctions have, with rare exceptions, noted only isolated linear or mildly curvilinear structures. In this study we noted gap junctional shapes on thin-section TEM preparations of osteoblasts and osteocytes to be extremely variable and complex encompassing linear, curvilinear, stacked linear, oval, and annular conformations. Multiple observations revealed linear gap junctions linking surface osteoblast cell bodies; linear, curvilinear, stacked linear, and oval junctions linking osteoblast processes in osteoid; linear and curvilinear junctions where cell processes joined with osteocyte cell bodies and each of the five conformations linking osteocyte processes within canaliculi. The annular junctions were found within osteoblast and osteocyte cytoplasm and in osteocyte cell processes within canaliculi. The annular junctions are intracellular, degenerating structures which appear as ultrastructural markers of gap junction involution. The more complex shapes reported here must be considered in (1) interpreting quantitative studies using freeze-fracture replicas, thin sections, and confocal microscopy immunolabeled junction connexin-43 components and (2) assessing gap junction biogenesis and turnover. 3-D reconstruction of bone junctions will enhance our understanding of these complex conformations.

  12. External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation

    Science.gov (United States)

    Patanaporn, Virush; Janhom, Apirum; Korwanich, Narumanus

    2012-01-01

    Purpose This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. Materials and Methods The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. Results The periapical radiographs of 564 teeth showed that the average root resorption was 1.39±1.27 (8.24±7.22%) and 1.69±1.14 mm (10.16±6.78%) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (poverjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. Conclusion These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration. PMID:23071964

  13. External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Nanekrungsan, Kamonporn [Dept. of Dentistry, Overbrook Hospital, Chiang Rai (Thailand); Patanaporn, Virush; Janhom, Apirum; Korwanich, Narumanus [Dept. of Chiang Mai University, Chiang Mai (Thailand)

    2012-09-15

    This study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption. The records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption. The periapical radiographs of 564 teeth showed that the average root resorption was 1.39{+-}1.27 (8.24{+-}7.22%) and 1.69{+-}1.14 mm (10.16{+-}6.78%) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket. These results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

  14. Two highly similar DEAD box proteins, OsRH2 and OsRH34, homologous to eukaryotic initiation factor 4AIII, play roles of the exon junction complex in regulating growth and development in rice.

    Science.gov (United States)

    Huang, Chun-Kai; Sie, Yi-Syuan; Chen, Yu-Fu; Huang, Tian-Sheng; Lu, Chung-An

    2016-04-12

    The exon junction complex (EJC), which contains four core components, eukaryotic initiation factor 4AIII (eIF4AIII), MAGO/NASHI (MAGO), Y14/Tsunagi/RNA-binding protein 8A, and Barentsz/Metastatic lymph node 51, is formed in both nucleus and cytoplasm, and plays important roles in gene expression. Genes encoding core EJC components have been found in plants, including rice. Currently, the functional characterizations of MAGO and Y14 homologs have been demonstrated in rice. However, it is still unknown whether eIF4AIII is essential for the functional EJC in rice. This study investigated two DEAD box RNA helicases, OsRH2 and OsRH34, which are homologous to eIF4AIII, in rice. Amino acid sequence analysis indicated that OsRH2 and OsRH34 had 99 % identity and 100 % similarity, and their gene expression patterns were similar in various rice tissues, but the level of OsRH2 mRNA was about 58-fold higher than that of OsRH34 mRNA in seedlings. From bimolecular fluorescence complementation results, OsRH2 and OsRH34 interacted physically with OsMAGO1 and OsY14b, respectively, which indicated that both of OsRH2 and OsRH34 were core components of the EJC in rice. To study the biological roles of OsRH2 and OsRH34 in rice, transgenic rice plants were generated by RNA interference. The phenotypes of three independent OsRH2 and OsRH34 double-knockdown transgenic lines included dwarfism, a short internode distance, reproductive delay, defective embryonic development, and a low seed setting rate. These phenotypes resembled those of mutants with gibberellin-related developmental defects. In addition, the OsRH2 and OsRH34 double-knockdown transgenic lines exhibited the accumulation of unspliced rice UNDEVELOPED TAPETUM 1 mRNA. Rice contains two eIF4AIII paralogous genes, OsRH2 and OsRH34. The abundance of OsRH2 mRNA was about 58-fold higher than that of OsRH34 mRNA in seedlings, suggesting that the OsRH2 is major eIF4AIII in rice. Both OsRH2 and OsRH34 are core components of the EJC

  15. Cryopreservation of Pelargonium apices by droplet-vitrification.

    Science.gov (United States)

    Gallard, Anthony; Panis, Bart; Dorion, Nöelle; Swennen, Rony; Grapin, Agnès

    2008-01-01

    The droplet-vitrification method was adapted to Pelargonium apices by optimizing the duration of the loading solution (LS) as well as the plant vitrification solution 2 (PVS2). The excised apices were dehydrated in two steps (20 min in LS and 15 min in PVS2) and then immersed directly in liquid nitrogen (LN). After thawing and unloading in the recovery solution at room temperature for 15 min, apices were plated onto semi-solid Murashige and Skoog medium. This simple protocol without any pretreatment was successfully applied to eight cultivars with a survival level ranging between 55.6 - 96.2 percent and a regrowth level between 9.1 and 70.6 percent. These results prove the feasibility of the long-term storage of Pelargonium germplasm through cryopreservation.

  16. Complex

    African Journals Online (AJOL)

    CLEMENT O BEWAJI

    Schiff bases and their complex compounds have been studied for their .... establishing coordination of the N–(2 – hydroxybenzyl) - L - α - valine Schiff base ..... (1967); “Spectrophotometric Identification of Organic Compounds”, Willey, New.

  17. Changes of Root Length and Root-to-Crown Ratio after Apical Surgery: An Analysis by Using Cone-beam Computed Tomography.

    Science.gov (United States)

    von Arx, Thomas; Jensen, Simon S; Bornstein, Michael M

    2015-09-01

    Apical surgery is an important treatment option for teeth with post-treatment periodontitis. Although apical surgery involves root-end resection, no morphometric data are yet available about root-end resection and its impact on the root-to-crown ratio (RCR). The present study assessed the length of apicectomy and calculated the loss of root length and changes of RCR after apical surgery. In a prospective clinical study, cone-beam computed tomography scans were taken preoperatively and postoperatively. From these images, the crown and root lengths of 61 roots (54 teeth in 47 patients) were measured before and after apical surgery. Data were collected relative to the cementoenamel junction (CEJ) as well as to the crestal bone level (CBL). One observer took all measurements twice (to calculate the intraobserver variability), and the means were used for further analysis. The following parameters were assessed for all treated teeth as well as for specific tooth groups: length of root-end resection and percentage change of root length, preoperative and postoperative RCRs, and percentage change of RCR after apical surgery. The mean length of root-end resection was 3.58 ± 1.43 mm (relative to the CBL). This amounted to a loss of 33.2% of clinical and 26% of anatomic root length. There was an overall significant difference between the tooth groups (P < .05). There was also a statistically significant difference comparing mandibular and maxillary teeth (P < .05), but not for incisors/canines versus premolars/molars (P = .125). The mean preoperative and postoperative RCRs (relative to CEJ) were 1.83 and 1.35, respectively (P < .001). With regard to the CBL reference, the mean preoperative and postoperative RCRs were 1.08 and 0.71 (CBL), respectively (P < .001). The calculated changes of RCR after apical surgery were 24.8% relative to CEJ and 33.3% relative to CBL (P < .001). Across the different tooth groups, the mean RCR was not significantly different (P = .244 for

  18. Association of a peptoid ligand with the apical loop of pri-miR-21 inhibits cleavage by Drosha.

    Science.gov (United States)

    Diaz, Jason P; Chirayil, Rachel; Chirayil, Sara; Tom, Martin; Head, Katie J; Luebke, Kevin J

    2014-04-01

    We have found a small molecule that specifically inhibits cleavage of a precursor to the oncogenic miRNA, miR-21, by the microprocessor complex of Drosha and DGCR8. We identified novel ligands for the apical loop of this precursor from a screen of 14,024 N-substituted oligoglycines (peptoids) in a microarray format. Eight distinct compounds with specific affinity were obtained, three having affinities for the targeted loop in the low micromolar range and greater than 15-fold discrimination against a closely related hairpin. One of these compounds completely inhibits microprocessor cleavage of a miR-21 primary transcript at concentrations at which cleavage of another miRNA primary transcript, pri-miR-16, is little affected. The apical loop of pri-miR-21, placed in the context of pri-miR-16, is sufficient for inhibition of microprocessor cleavage by the peptoid. This compound also inhibits cleavage of pri-miR-21 containing the pri-miR-16 apical loop, suggesting an additional site of association within pri-miR-21. The reported peptoid is the first example of a small molecule that inhibits microprocessor cleavage by binding to the apical loop of a pri-miRNA.

  19. Unique apicomplexan IMC sub-compartment proteins are early markers for apical polarity in the malaria parasite.

    Science.gov (United States)

    Poulin, Benoit; Patzewitz, Eva-Maria; Brady, Declan; Silvie, Olivier; Wright, Megan H; Ferguson, David J P; Wall, Richard J; Whipple, Sarah; Guttery, David S; Tate, Edward W; Wickstead, Bill; Holder, Anthony A; Tewari, Rita

    2013-01-01

    The phylum Apicomplexa comprises over 5000 intracellular protozoan parasites, including Plasmodium and Toxoplasma, that are clinically important pathogens affecting humans and livestock. Malaria parasites belonging to the genus Plasmodium possess a pellicle comprised of a plasmalemma and inner membrane complex (IMC), which is implicated in parasite motility and invasion. Using live cell imaging and reverse genetics in the rodent malaria model P. berghei, we localise two unique IMC sub-compartment proteins (ISPs) and examine their role in defining apical polarity during zygote (ookinete) development. We show that these proteins localise to the anterior apical end of the parasite where IMC organisation is initiated, and are expressed at all developmental stages, especially those that are invasive. Both ISP proteins are N-myristoylated, phosphorylated and membrane-bound. Gene disruption studies suggest that ISP1 is likely essential for parasite development, whereas ISP3 is not. However, an absence of ISP3 alters the apical localisation of ISP1 in all invasive stages including ookinetes and sporozoites, suggesting a coordinated function for these proteins in the organisation of apical polarity in the parasite.

  20. Unique apicomplexan IMC sub-compartment proteins are early markers for apical polarity in the malaria parasite

    Directory of Open Access Journals (Sweden)

    Benoit Poulin

    2013-09-01

    The phylum Apicomplexa comprises over 5000 intracellular protozoan parasites, including Plasmodium and Toxoplasma, that are clinically important pathogens affecting humans and livestock. Malaria parasites belonging to the genus Plasmodium possess a pellicle comprised of a plasmalemma and inner membrane complex (IMC, which is implicated in parasite motility and invasion. Using live cell imaging and reverse genetics in the rodent malaria model P. berghei, we localise two unique IMC sub-compartment proteins (ISPs and examine their role in defining apical polarity during zygote (ookinete development. We show that these proteins localise to the anterior apical end of the parasite where IMC organisation is initiated, and are expressed at all developmental stages, especially those that are invasive. Both ISP proteins are N-myristoylated, phosphorylated and membrane-bound. Gene disruption studies suggest that ISP1 is likely essential for parasite development, whereas ISP3 is not. However, an absence of ISP3 alters the apical localisation of ISP1 in all invasive stages including ookinetes and sporozoites, suggesting a coordinated function for these proteins in the organisation of apical polarity in the parasite.

  1. Mixing in T-junctions

    NARCIS (Netherlands)

    Kok, Jacobus B.W.; van der Wal, S.

    1996-01-01

    The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction

  2. Vitamin D increases tight-junction conductance and paracellular Ca2+ transport in Caco-2 cell cultures.

    Science.gov (United States)

    Chirayath, M V; Gajdzik, L; Hulla, W; Graf, J; Cross, H S; Peterlik, M

    1998-02-01

    We investigated the effects of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] on paracellular intestinal Ca2+ absorption by determination of transepithelial electric resistance (TEER), as a measure of tight-junction ion permeability and bidirectional transepithelial 45Ca2+ fluxes in confluent Caco-2 cell cultures. The rise of TEER to steady-state levels of approximately 2,000 omega.cm2 was significantly attenuated by 1,25(OH)2D3 (by up to 50%) in a dose-dependent fashion between 10(-11) and 10(-8) M. Synthetic analogs of 1,25(OH)2D3, namely, 1 alpha,25-dihydroxy-16-ene,23-yne-vitamin D3 and 1 alpha,25-dihydroxy-26,27-hexafluoro-16-ene,23-yne-vitamin D3, exhibited similar biopotency, whereas their genomically inactive 1-deoxy congeners were only marginally effective. Enhancement of transepithelial conductance of Caco-2 cell monolayers by vitamin D was accompanied by a significant increase in bidirectional transepithelial 45Ca2+ fluxes. Although 1,25(OH)2D3 also induced cellular 45Ca2+ uptake from the apical aspect of Caco-2 cell layers and upregulated the expression of calbindin-9kDa mRNA, no significant contribution of the Ca(2+)-adenosinetriphosphatase-mediated transcellular pathway to transepithelial Ca2+ transport could be detected. Therefore stimulation of Ca2+ fluxes across confluent Caco-2 cells very likely results from a genomic effect of vitamin D sterols on assembly and permeability of tight-junctional complexes.

  3. Influence of the parameters of the Er:YAG laser on the apical sealing of apicectomized teeth.

    Science.gov (United States)

    Marques, Aparecida Maria Cordeiro; Gerbi, Marleny Elizabeth M M; dos Santos, Jean Nunes; Noia, Manuela Pimentel; Oliveira, Priscila Chagas; Brugnera Junior, Aldo; Zanin, Fátima Antonia Aparecida; Pinheiro, Antonio Luiz Barbosa

    2011-07-01

    Failures in the sealing of the tooth apex have been considered to be responsible for most of the failures of apical surgeries. The Er:YAG laser has been proposed as an alternative for the use of rotator instruments in surgical endodontics due to its precision, lack of vibration, less post-operative discomfort, bacterial reduction, and less stress for patients and professionals. Following approval by the ethics committee, 12 extracted human canines without previous endodontic treatment with anatomically normal roots and free from apical lesions were washed in running tap water and disinfected. The teeth were sectioned axially at the crown-root junction and submitted to routine endodontic treatment. The apical limit was set at 1 mm before the apical foramen. The root canals were routinely filled with Gutta-Percha points and Sealer 26 and were randomly distributed into two groups (n = 6). In group I, apicectomy was performed with the Er:YAG laser (KAVO KEY Laser II®, Germany, λ = 2.940 nm, pulsed mode, 2051 tip, with air spray cooling, 250 mJ/15 Hz). Apical cut was performed of perpendicular mode 3 mm from the apical foramen. In group II, the same procedures and the same sequence as above was used, varying only the parameters of the Er:YAG laser (400 mJ/6 Hz). Sealing of the cervical end the apex was carried out with acrylic resin; the roots were covered by a layer of epoxy glue and two layers of nail polish. The specimens were divided into groups and fixed, by the cervical third, on wax. Impermeabilization of the residual root apical third was performed following the same procedures used in the cervical third but the residual apex was left free from the impermeabilization. After that, the roots were immersed in a 2% methylene blue solution and placed in a bacteriological oven for 48 h and then washed in running tap water for 2 h. The samples were sagittally split into two parts. The segments were visually observed and the one showing the greatest

  4. [Nonsurgical retreatment in a case of a radiolucent apical lesion].

    Science.gov (United States)

    Vicente Gómez, A; Rodríguez Ponce, A

    1989-01-01

    We present a case of failure that was helpful solved without surgical endodontic treatment. We don't achieve clinical success besides endodontic treatment was twice remade. Finally we decided to put a temporary filling with calcium hydroxide and wait until apical radiolucency disappear and complete our treatment with gutta-percha, sealer and lateral condensation.

  5. Assessment of apical periodontitis by MRI. A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Geibel, M.A. [Ulm Univ. (Germany). Oral and Maxillofacial Surgery; Schreiber, E.S.; Bracher, A.K.; Rasche, V. [Ulm Univ. (Germany). Internal Medicine II; Hell, E.; Ulrici, J. [Sirona Dental Systems GmbH, Bensheim (Germany). Dental Imaging; Sailer, L.K. [DOC Praxisklinik im Wiley, Neu-Ulm (Germany). MKG; Ozpeynirci, Y. [Ulm Univ. (Germany). Diagnostic and Interventional Radiology

    2015-04-15

    The purpose of this clinical feasibility study was to evaluate the applicability of magnetic resonance imaging (MRI) for the assessment of apical periodontitis in direct comparison with cone beam CT (CBCT). 19 consecutive patients (average age 43 ± 13 years) with 34 lesions in total (13 molars, 14 premolars and 7 front teeth) were enrolled in this feasibility study. Periapical lesions were defined as periapical radiolucencies (CBCT) or structural changes in the spongy bone signal (MRI), which were connected with the apical part of a root and with at least twice the width of the periodontal ligament space. The location and dimension of the lesions were compared between MRI and CBCT. While mainly mineralized tissue components such as teeth and bone were visible with CBCT, complimentary information of the soft tissue components was assessable with MRI. The MRI images provided sufficient diagnostic detail for the assessment of the main structures of interest. Heterogeneous contrast was observed within the lesion, with often a clear enhancement close to the apical foramen and the periodontal gap. No difference for lesion visibility was observed between MRI and CBCT. The lesion dimensions corresponded well, but were slightly but significantly overestimated with MRI. A heterogeneous lesion appearance was observed in several patients. Four patients presented with a well circumscribed hyperintense signal in the vicinity of the apical foramen. The MRI capability of soft tissue characterization may facilitate detailed analysis of periapical lesions. This clinical study confirms the applicability of multi-contrast MRI for the identification of periapical lesions.

  6. Hypertrophic cardiomyopathy with apical left ventricular aneurysm: a case report

    Institute of Scientific and Technical Information of China (English)

    江腾勇; 韩智红; 王京; 吕强; 吴学思

    2002-01-01

    @@ Morphological diversity is one characteristic of hypertrophic cardi omyopathy (HCM), but it is not common that HCM is associated with apical left ve ntricular aneurysm (LVA) without evidence of a coronary artery lesion. We repor t on such a case and review the pathogenesis, manifestations and diagnostic meth ods by collecting the few available papers published on this topic.

  7. Apical vault repair, the cornerstone or pelvic vault reconstruction.

    Science.gov (United States)

    Ross, J W

    1997-01-01

    Pelvic organ prolapse remains a difficult problem for pelvic reconstructive surgery. Before new surgical procedures can be developed a good understanding of pelvic anatomy is necessary. It is widely held that the etiology of pelvic organ prolapse is secondary to stretch neuropathy following childbirth and chronic cough or constipation. Several transvaginal and transabdominal procedures have been developed over the years. With the increasing use of laparoscopy, a new variation on existing culdeplasty techniques has been developed. Following anatomical principles, the apical vault repair reestablishes the pericervical ring at the vaginal apex. The incorporation of pubocervical fascia, uterosacral-cardinal ligament and the rectovaginal fascia provides a strong anchor for the vaginal apex. In addition, the repair should help prevent future transverse cystocele, rectocele, enterocele and apical vault prolapse. Early outcome studies suggest that the apical vault repair should be used routinely with laparoscopic urethropexy, laparoscopic hysterectomy and the repair of pelvic organ prolapse. Good apical vault support is considered the cornerstone of pelvic reconstruction.

  8. The apical plasma membrane of chitin-synthesizing epithelia

    Institute of Scientific and Technical Information of China (English)

    Bernard Moussian

    2013-01-01

    Chitin is the second most abundant polysaccharide on earth.It is produced at the apical side of epidermal,tracheal,fore-,and hindgut epithelial cells in insects as a central component of the protective and supporting extracellular cuticle.Chitin is also an important constituent of the midgut peritrophic matrix that encases the food supporting its digestion and protects the epithelium against invasion by possibly ingested pathogens.The enzyme producing chitin is a glycosyltransferase that resides in the apical plasma membrane forming a pore to extrude the chains of chitin into the extracellular space.The apical plasma membrane is not only a platform for chitin synthases but,probably through its shape and equipment with distinct factors,also plays an important role in orienting and organizing chitin fibers.Here,I review findings on the cellular and molecular constitution of the apical plasma membrane of chitin-producing epithelia mainly focusing on work done in the fruit fly Drosophila melanogaster.

  9. Apical root resorption after orthodontic treatment -- a retrospective study.

    Science.gov (United States)

    Apajalahti, Satu; Peltola, Jaakko Sakari

    2007-08-01

    The purpose of the study was to compare the incidence and severity of apical root resorption in patients treated with different orthodontic appliances and to evaluate the effect of treatment duration on the degree of apical root resorption. A further aim was to analyse the degree of apical root resorption in different tooth groups in patients presenting with root resorption. The sample consisted of 625 patients (269 males, 356 females) aged 8-16 years at the beginning of treatment. Active removable plates and fixed appliances were used most frequently. Following exclusion of poor quality radiographs, the final sample included 601 patients (348 females, 253 males). Root resorption in all tooth groups, except third molars, was evaluated from pre- and post-treatment panoramic radiographs. The correlation of root resorption with treatment modality and duration was studied using multinomial logistic regression analysis. Of the tooth groups, maxillary incisors showed apical root resorption most frequently, followed by the mandibular incisors. Root resorption was significantly correlated with fixed appliance treatment (P resorption. The mean duration of treatment in patients without root resorption was 1.5 years, whereas in those with severe resorption was 2.3 years. The most severe resorption was seen in the maxillary incisors and premolars. It is concluded that with a long duration of fixed appliance treatment, the risk of severe resorption increases. In patients where treatment is prolonged, a 6-month radiographic follow-up is recommended.

  10. Chapter Four - Shoot apical meristem form and function. In:

    Science.gov (United States)

    The shoot apical meristem (SAM) generates above-ground aerial organs throughout the lifespan of higher plants. In order to fulfill this function, the meristem must maintain a balance between the self-renewal of a reservoir of central stem cells and organ initiation from peripheral cells. The activit...

  11. c-Yes regulates cell adhesion at the apical ectoplasmic specialization-blood-testis barrier axis via its effects on protein recruitment and distribution

    Science.gov (United States)

    Xiao, Xiang; Mruk, Dolores D.

    2013-01-01

    During spermatogenesis, extensive restructuring takes place at the cell-cell interface since developing germ cells migrate progressively from the basal to the adluminal compartment of the seminiferous epithelium. Since germ cells per se are not motile cells, their movement relies almost exclusively on the Sertoli cell. Nonetheless, extensive exchanges in signaling take place between these cells in the seminiferous epithelium. c-Yes, a nonreceptor protein tyrosine kinase belonging to the Src family kinases (SFKs) and a crucial signaling protein, was recently shown to be upregulated at the Sertoli cell-cell interface at the blood-testis barrier (BTB) at stages VIII–IX of the seminiferous epithelial cycle of spermatogenesis. It was also highly expressed at the Sertoli cell-spermatid interface known as apical ectoplasmic specialization (apical ES) at stage V to early stage VIII of the epithelial cycle during spermiogenesis. Herein, it was shown that the knockdown of c-Yes by RNAi in vitro and in vivo affected both Sertoli cell adhesion at the BTB and spermatid adhesion at the apical ES, causing a disruption of the Sertoli cell tight junction-permeability barrier function, germ cell loss from the seminiferous epithelium, and also a loss of spermatid polarity. These effects were shown to be mediated by changes in distribution and/or localization of adhesion proteins at the BTB (e.g., occludin, N-cadherin) and at the apical ES (e.g., nectin-3) and possibly the result of changes in the underlying actin filaments at the BTB and the apical ES. These findings implicate that c-Yes is a likely target of male contraceptive research. PMID:23169788

  12. Comparison of the Root End Sealing Ability of Four Different Retrograde Filling Materials in Teeth with Root Apices Resected at Different Angles – An Invitro Study

    Science.gov (United States)

    Ponnappa, K.C.; Yadav, Pankaj; Rao, Yogesh; Relhan, Nikhil; Gupta, Priyanka; Choubey, Ashish; Bhardwaj, Shivanshu

    2016-01-01

    Introduction Insufficient apical seal is the significant reason for surgical endodontic disappointment. The root-end filling material utilized should avoid egress of potential contaminants into periapical tissue. Aim The aim of this study was to compare the sealing ability of four root-end filling materials MTA, Portland cement, IRM, RMGIC in teeth with root apices resected at 0 and 45 angle using dye penetration method under fluorescent microscope. Materials and Methods Hundred extracted human maxillary anterior teeth were sectioned horizontally at the cement-enamel junction. After cleaning, shaping and obturation with gutta-percha and AH Plus sealer, the tooth samples were randomly divided in two groups (the root apices resected at 0° and 45° to the long axis of the root). The root resections were carried out by removing 2 mm and 1 mm in both the groups. Following which 3 mm deep root-end cavities were prepared at the apices and the root were coated with nail varnish except the tip. The teeth in both the group were randomly divided into four subgroups each (Pro root MTA, Portland cement, IRM and Light cure nano GIC Ketac N-100). All the retrofilled samples were stored in acrydine orange for 24 hours after which they were cleaned and vertically sectioned buccolingually. The sectioned root samples were observed under fluorescent microscope. Results The root apex sealing ability of Mineral Trioxide Aggregate (MTA) was superior to Portland cement, Intermediate Restorative Material (IRM) and LC GIC. IRM demonstrated the maximum apical leakage value among all the materials. Portland cement and LC GIC showed comparable sealing ability. Conclusion The angulation whether 0° or 45° angle did not affect the sealing ability of all the four materials used, MTA proved to be one of the superior materials for root-end filling. PMID:26894168

  13. c-Yes regulates cell adhesion at the apical ectoplasmic specialization-blood-testis barrier axis via its effects on protein recruitment and distribution.

    Science.gov (United States)

    Xiao, Xiang; Mruk, Dolores D; Cheng, C Yan

    2013-01-15

    During spermatogenesis, extensive restructuring takes place at the cell-cell interface since developing germ cells migrate progressively from the basal to the adluminal compartment of the seminiferous epithelium. Since germ cells per se are not motile cells, their movement relies almost exclusively on the Sertoli cell. Nonetheless, extensive exchanges in signaling take place between these cells in the seminiferous epithelium. c-Yes, a nonreceptor protein tyrosine kinase belonging to the Src family kinases (SFKs) and a crucial signaling protein, was recently shown to be upregulated at the Sertoli cell-cell interface at the blood-testis barrier (BTB) at stages VIII-IX of the seminiferous epithelial cycle of spermatogenesis. It was also highly expressed at the Sertoli cell-spermatid interface known as apical ectoplasmic specialization (apical ES) at stage V to early stage VIII of the epithelial cycle during spermiogenesis. Herein, it was shown that the knockdown of c-Yes by RNAi in vitro and in vivo affected both Sertoli cell adhesion at the BTB and spermatid adhesion at the apical ES, causing a disruption of the Sertoli cell tight junction-permeability barrier function, germ cell loss from the seminiferous epithelium, and also a loss of spermatid polarity. These effects were shown to be mediated by changes in distribution and/or localization of adhesion proteins at the BTB (e.g., occludin, N-cadherin) and at the apical ES (e.g., nectin-3) and possibly the result of changes in the underlying actin filaments at the BTB and the apical ES. These findings implicate that c-Yes is a likely target of male contraceptive research.

  14. CLINICAL EFFECTIVENESS OF TREATMENT THE PATIENTS WITH CHRONIC APICAL PERIODONTITIS

    Directory of Open Access Journals (Sweden)

    N. G. Gadzhula

    2017-02-01

    Full Text Available Background. The success of endodontic treatment is provided by a thorough instrumental and antiseptic treatment of infected root canals, and it depends on the composition of filling material, the degree of adhesion to dentin, hermetic obturation of apical foramen, solubility of sealer. Objective. The study was aimed to evaluate the effectiveness of root canal obturation with BioRootTM RCS sealer in the treatment of patients with chronic apical periodontitis. Methods. Endodontic treatment of 23 teeth in 20 patients with chronic apical periodontitis by method of lateral compaction of gutta-percha was carried out. In the main group root canals were obturated with BioRootTM RCS, in the control group the canals were filled with Apexit Plus. The percentage of efficient or non-efficient cases was evaluated on the basis of radiographic comparison of treated chronic apical periodontitis immediately after obturation, in three, six months and one year. Radiographic conditions were defined as existing state, improvement and worsening. Results. In a year of dynamic evaluation the final results were: in the main group – 54.55% of the patients had complete bone healing, in 27.27% of cases the focus of bone destruction was decreased by ½ or more of the initial sizes, 18.18% – resorption lesion was decreased by less than ½; in the control group – 33.33% of improvement, 25.0% of existing state and 41.66% of worsening. Conclusions. BioRootTM RCS using for root canals obturation in the treatment of chronic apical periodontitis we proved the high effectiveness of the treatment undertaken: complete healing or improvement of radiographic conditions of periapical bone destruction with X-ray signs of bone regeneration.

  15. Structural Molecular Components of Septate Junctions in Cnidarians Point to the Origin of Epithelial Junctions in Eukaryotes

    KAUST Repository

    Ganot, P.

    2014-09-21

    Septate junctions (SJs) insure barrier properties and control paracellular diffusion of solutes across epithelia in invertebrates. However, the origin and evolution of their molecular constituents in Metazoa have not been firmly established. Here, we investigated the genomes of early branching metazoan representatives to reconstruct the phylogeny of the molecular components of SJs. Although Claudins and SJ cytoplasmic adaptor components appeared successively throughout metazoan evolution, the structural components of SJs arose at the time of Placozoa/Cnidaria/Bilateria radiation. We also show that in the scleractinian coral Stylophora pistillata, the structural SJ component Neurexin IV colocalizes with the cortical actin network at the apical border of the cells, at the place of SJs. We propose a model for SJ components in Cnidaria. Moreover, our study reveals an unanticipated diversity of SJ structural component variants in cnidarians. This diversity correlates with gene-specific expression in calcifying and noncalcifying tissues, suggesting specific paracellular pathways across the cell layers of these diploblastic animals.

  16. Gap junction channels and cardiac impulse propagation.

    Science.gov (United States)

    Desplantez, Thomas; Dupont, Emmanuel; Severs, Nicholas J; Weingart, Robert

    2007-08-01

    The role of gap junction channels on cardiac impulse propagation is complex. This review focuses on the differential expression of connexins in the heart and the biophysical properties of gap junction channels under normal and disease conditions. Structural determinants of impulse propagation have been gained from biochemical and immunocytochemical studies performed on tissue extracts and intact cardiac tissue. These have defined the distinctive connexin coexpression patterns and relative levels in different cardiac tissues. Functional determinants of impulse propagation have emerged from electrophysiological experiments carried out on cell pairs. The static properties (channel number and conductance) limit the current flow between adjacent cardiomyocytes and thus set the basic conduction velocity. The dynamic properties (voltage-sensitive gating and kinetics of channels) are responsible for a modulation of the conduction velocity during propagated action potentials. The effect is moderate and depends on the type of Cx and channel. For homomeric-homotypic channels, the influence is small to medium; for homomeric-heterotypic channels, it is medium to strong. Since no data are currently available on heteromeric channels, their influence on impulse propagation is speculative. The modulation by gap junction channels is most prominent in tissues at the boundaries between cardiac tissues such as sinoatrial node-atrial muscle, atrioventricular node-His bundle, His bundle-bundle branch and Purkinje fibers-ventricular muscle. The data predict facilitation of orthodromic propagation.

  17. Function and regulation of transcription factors involved in root apical meristem and stem cell maintenance

    Directory of Open Access Journals (Sweden)

    Rebecca Corinna Drisch

    2015-07-01

    Full Text Available Plant roots are essential for overall plant development, growth and performance by providing anchorage in the soil and uptake of nutrients and water. The primary root of higher plants derives from a group of pluripotent, mitotically active stem cells residing in the root apical meristem (RAM which provides the basis for growth, development and regeneration of the root. The stem cells in the Arabidopsis thaliana RAM are surrounding the quiescent center (QC, which consists of a group of rarely dividing cells. The QC maintains the stem cells in a non-cell-autonomous manner and prevents them from differentiation. The necessary dynamic but also tight regulation of the transition from stem cell fate to differentiation most likely requires complex regulatory mechanisms to integrate external and internal cues. Transcription factors play a central role in root development and are regulated by phytohormones, small signaling molecules and miRNAs. In this review we give a comprehensive overview about the function and regulation of specific transcription factors controlling stem cell fate and root apical meristem maintenance and discuss the possibility of TF complex formation, subcellular translocations and cell-to-cell movement functioning as another level of regulation.

  18. Metallic Junction Thermoelectric Device Simulations

    Science.gov (United States)

    Duzik, Adam J.; Choi, Sang H.

    2017-01-01

    Thermoelectric junctions made of semiconductors have existed in radioisotope thermoelectric generators (RTG) for deep space missions, but are currently being adapted for terrestrial energy harvesting. Unfortunately, these devices are inefficient, operating at only 7% efficiency. This low efficiency has driven efforts to make high-figure-of-merit thermoelectric devices, which require a high electrical conductivity but a low thermal conductivity, a combination that is difficult to achieve. Lowered thermal conductivity has increased efficiency, but at the cost of power output. An alternative setup is to use metallic junctions rather than semiconductors as thermoelectric devices. Metals have orders of magnitude more electrons and electronic conductivities higher than semiconductors, but thermal conductivity is higher as well. To evaluate the viability of metallic junction thermoelectrics, a two dimensional heat transfer MATLAB simulation was constructed to calculate efficiency and power output. High Seebeck coefficient alloys, Chromel (90%Ni-10%Cr) and Constantan (55%Cu-45%Ni), produced efficiencies of around 20-30%. Parameters such as the number of layers of junctions, lateral junction density, and junction sizes for both series- and parallel-connected junctions were explored.

  19. HANABA TARANU regulates the shoot apical meristem and leaf development in cucumber (Cucumis sativus L.).

    Science.gov (United States)

    Ding, Lian; Yan, Shuangshuang; Jiang, Li; Liu, Meiling; Zhang, Juan; Zhao, Jianyu; Zhao, Wensheng; Han, Ying-Yan; Wang, Qian; Zhang, Xiaolan

    2015-12-01

    The shoot apical meristem (SAM) is essential for continuous organogenesis in higher plants, while the leaf is the primary source organ and the leaf shape directly affects the efficiency of photosynthesis. HANABA TARANU (HAN) encodes a GATA3-type transcription factor that functions in floral organ development, SAM organization, and embryo development in Arabidopsis, but is involved in suppressing bract outgrowth and promoting branching in grass species. Here the function of the HAN homologue CsHAN1 was characterized in cucumber, an important vegetable with great agricultural and economic value. CsHAN1 is predominantly expressed at the junction of the SAM and the stem, and can partially rescue the han-2 floral organ phenotype in Arabidopsis. Overexpression and RNAi of CsHAN1 transgenic cucumber resulted in retarded growth early after embryogenesis and produced highly lobed leaves. Further, it was found that CsHAN1 may regulate SAM development through regulating the WUSCHEL (WUS) and SHOOT MERISTEMLESS (STM) pathways, and mediate leaf development through a complicated gene regulatory network in cucumber.

  20. Affordance-based individuation of junctions in Open Street Map

    Directory of Open Access Journals (Sweden)

    Simon Scheider

    2012-06-01

    Full Text Available We propose an algorithm that can be used to identify automatically the subset of street segments of a road network map that corresponds to a junction. The main idea is to use turn-compliant locomotion affordances, i.e., restricted patterns of supported movement, in order to specify junctions independently of their data representation, and in order to motivate tractable individuation and classification strategies. We argue that common approaches based solely on geometry or topology of the street segment graph are useful but insufficient proxies. They miss certain turn restrictions essential to junctions. From a computational viewpoint, the main challenge of affordance-based individuation of junctions lies in its complex recursive definition. In this paper, we show how Open Street Map data can be interpreted into locomotion affordances, and how the recursive junction definition can be translated into a deterministic algorithm. We evaluate this algorithm by applying it to small map excerpts in order to delineate the contained junctions.

  1. SMIT2 mediates all myo-inositol uptake in apical membranes of rat small intestine

    National Research Council Canada - National Science Library

    Rym Aouameur; Sandra Da Cal; Pierre Bissonnette; Michael J. Coady; Jean-Yves Lapointe

    2007-01-01

    ...; rabbit intestine appears to lack apical transport of MI. Other sugar transport systems known to be present in apical membranes, such as SGLT1 or GLUT5, lacked any significant contribution to MI uptake...

  2. Anatomy and biomechanics of the craniovertebral junction.

    Science.gov (United States)

    Lopez, Alejandro J; Scheer, Justin K; Leibl, Kayla E; Smith, Zachary A; Dlouhy, Brian J; Dahdaleh, Nader S

    2015-04-01

    The craniovertebral junction (CVJ) has unique anatomical structures that separate it from the subaxial cervical spine. In addition to housing vital neural and vascular structures, the majority of cranial flexion, extension, and axial rotation is accomplished at the CVJ. A complex combination of osseous and ligamentous supports allow for stability despite a large degree of motion. An understanding of anatomy and biomechanics is essential to effectively evaluate and address the various pathological processes that may affect this region. Therefore, the authors present an up-to-date narrative review of CVJ anatomy, normal and pathological biomechanics, and fixation techniques.

  3. Imaging of cervicothoracic junction trauma

    Directory of Open Access Journals (Sweden)

    Wongwaisayawan S

    2013-01-01

    Full Text Available Sirote Wongwaisayawan,1 Ruedeekorn Suwannanon,2 Rathachai Kaewlai11Department of Radiology, Ramathibodi Hospital and Mahidol University, Bangkok, Thailand; 2Department of Radiology, Faculty of Medicine, Prince of Songkla University, Hat Yai, ThailandAbstract: Cervicothoracic junction trauma is an important cause of morbidity and mortality in trauma patients. Imaging has played an important role in identifying injuries and guiding appropriate, timely therapy. Computed tomography is currently a method of choice for diagnosing cervicothoracic junction trauma, in which the pattern of injuries often suggests possible mechanisms and potential injuries. In this article, the authors describe and illustrate common and uncommon injuries that can occur in the cervicothoracic junction.Keywords: cervicothoracic junction, cervical spine, trauma, imaging, radiology

  4. A novel mitochondrial ATP8 gene mutation in a patient with apical hypertrophic cardiomyopathy and neuropathy

    Science.gov (United States)

    Jonckheere, An I; Hogeveen, Marije; Nijtmans, Leo; van den Brand, Mariel; Janssen, Antoon; Diepstra, Heleen; van den Brandt, Frans; van den Heuvel, Bert; Hol, Frans; Hofste, Tom; Kapusta, Livia; Dillmann, U; Shamdeen, M; Smeitink, J; Smeitink, J; Rodenburg, Richard

    2009-01-01

    To identify the biochemical and molecular genetic defect in a 16-year-old patient presenting with apical hypertrophic cardiomyopathy and neuropathy suspected for a mitochondrial disorder. Measurement of the mitochondrial energy-generating system (MEGS) capacity in muscle and enzyme analysis in muscle and fibroblasts were performed. Relevant parts of the mitochondrial DNA were analysed by sequencing. A homoplasmic nonsense mutation m.8529G→A (p.Trp55X) was found in the mitochondrial ATP8 gene in the patient’s fibroblasts and muscle tissue. Reduced complex V activity was measured in the patient’s fibroblasts and muscle tissue, and was confirmed in cybrid clones containing patient-derived mitochondrial DNA We describe the first pathogenic mutation in the mitochondrial ATP8 gene, resulting in an improper assembly and reduced activity of the complex V holoenzyme. PMID:21686774

  5. Interventricular cardiac resynchronization with right ventricular apical pacing in a patient with Ebstein's defect.

    Science.gov (United States)

    Maffe, Stefano; Perucca, Antonello; Paffoni, Paola; Signorotti, Fabiana; Pardo, Nicolò Franchetti; Dellavesa, Pierfranco; Parravicini, Umberto; Zenone, Franco; Paino, Anna Maria; Bielli, Massimo; Carola, Federico; Zanetta, Marco

    2008-06-01

    We present the case of a patient with Ebstein's defect surgically corrected, and a complete right bundle branch block (RBBB) documented on echocardiogram. After an episode of near syncope due to a high-grade atrioventricular (AV) block, the patient was assisted with a bicameral DDDR pacemaker implanted with traditional right ventricular apical pacing. After the DDDR, and after stimulation with an AV delay of 180 ms, a narrow QRS complex was observed. Meanwhile, the typical left bundle branch block morphology of the right ventricular pacing and the native RBBB morphology were missing. The QRS complex narrowing persisted, even with physical activity and also with the heart rate progression. An echocardiographic study confirmed an improvement of the cardiac resynchronization parameters with this programmed stimulation.

  6. The Antituberculosis Drug Ethambutol Selectively Blocks Apical Growth in CMN Group Bacteria

    Science.gov (United States)

    Schubert, Karin; Sieger, Boris; Meyer, Fabian; Giacomelli, Giacomo; Böhm, Kati; Rieblinger, Angela; Lindenthal, Laura; Sachs, Nadja; Wanner, Gerhard

    2017-01-01

    ABSTRACT Members of the genus Mycobacterium are the most prevalent cause of infectious diseases. Mycobacteria have a complex cell envelope containing a peptidoglycan layer and an additional arabinogalactan polymer to which a mycolic acid bilayer is linked; this complex, multilayered cell wall composition (mAGP) is conserved among all CMN group bacteria. The arabinogalactan and mycolic acid synthesis pathways constitute effective drug targets for tuberculosis treatment. Ethambutol (EMB), a classical antituberculosis drug, inhibits the synthesis of the arabinose polymer. Although EMB acts bacteriostatically, its underlying molecular mechanism remains unclear. Here, we used Corynebacterium glutamicum and Mycobacterium phlei as model organisms to study the effects of EMB at the single-cell level. Our results demonstrate that EMB specifically blocks apical cell wall synthesis, but not cell division, explaining the bacteriostatic effect of EMB. Furthermore, the data suggest that members of the family Corynebacterineae have two dedicated machineries for cell elongation (elongasome) and cytokinesis (divisome). PMID:28174310

  7. Demonstrated Anomalous Pancreaticobiliary Ductal Junction

    OpenAIRE

    Koçkar, Cem; ?ENOL, Altu?; BA?TÜRK, Abdulkadir; AYDIN, Bünyamin; Cüre, Erkan

    2015-01-01

    Anomalies of the pancreaticobiliary junction are rare. Clinically anomalies of the pancreaticobiliary junction are uncommonly symptomatic but may present themselves with associated conditions ranging from benign acute abdominal pain to carcinomas. A 52 years old man was admitted to gastroenterology service with complaints of fever, nausea, vomiting and recurrent epigastric pain. He was diagnosed with biliary pancreatitis. Endoscopic retrograde cholangiopancreato-graphy was performed. Papilla ...

  8. Josephson junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Georg Hermann

    2012-03-04

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  9. Electronic thermometry in tunable tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  10. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-09-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  11. Through-flow of water in leaves of a submerged plant is influenced by the apical opening

    DEFF Research Database (Denmark)

    Pedersen, Ole; Jørgensen, Lise Bolt; Sand-Jensen, Kaj

    1997-01-01

    Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity......Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity...

  12. Apical versus Basal Neurogenesis Directs Cortical Interneuron Subclass Fate

    Directory of Open Access Journals (Sweden)

    Timothy J. Petros

    2015-11-01

    Full Text Available Fate determination in the mammalian telencephalon, with its diversity of neuronal subtypes and relevance to neuropsychiatric disease, remains a critical area of study in neuroscience. Most studies investigating this topic focus on the diversity of neural progenitors within spatial and temporal domains along the lateral ventricles. Often overlooked is whether the location of neurogenesis within a fate-restricted domain is associated with, or instructive for, distinct neuronal fates. Here, we use in vivo fate mapping and the manipulation of neurogenic location to demonstrate that apical versus basal neurogenesis influences the fate determination of major subgroups of cortical interneurons derived from the subcortical telencephalon. Somatostatin-expressing interneurons arise mainly from apical divisions along the ventricular surface, whereas parvalbumin-expressing interneurons originate predominantly from basal divisions in the subventricular zone. As manipulations that shift neurogenic location alter interneuron subclass fate, these results add an additional dimension to the spatial-temporal determinants of neuronal fate determination.

  13. [Pulmonary hydatid cyst: unusual double apical location. About a case].

    Science.gov (United States)

    Sajiai, Hafsa; Rachidi, Mariam; Aitbatahar, Salma; Serhane, Hind; Amro, Lamyae

    2016-01-01

    Hydatid cyst (KH) is still endemic in several areas of Morocco. Pulmonary involvement is a consequence of liver disease. Hydatid cyst is characterized by diverse anatomical and clinical presentations and by the possibility of multiple locations within the lung parenchyma, predominantly involving pulmonary bases. We report the case of Mr J. M, 54 years old, admitted with suspected pulmonary hydatid cyst based on chest pain lasting for six months and an episode of hydatidoptysis. Chest x-ray objectified a double apical location suggesting different stages of evolution for pulmonary hydatid cyst. The diagnosis was confirmed by thoracic CTscan and hydatid serology. Multiple pulmonary hydatid cyst is not rare in areas in which hydatid disease is highly endemic. Our study reports an unusual double apical location of hydatid cyst at various stages of evolution.

  14. [An endodontic ultrasonic system for apical endodontic surgery].

    Science.gov (United States)

    de Lange, I; Putters, T; Baas, E M; van Ingen, J M

    2009-09-01

    Apical endodontic surgery is applied frequently following a failed conventional endodontic treatment. The apical preparation can be carried out conventionally using a round bur or using an endodontic ultrasonic system. The purpose of this study was to compare the outcome of the 2 treatment options by a randomized prospective clinical study. Patients (n=399) were at random allocated to treatment using a conventional round bur or using an ultrasonic system (P-max Newtron) according to a for the rest similar treatment protocol. One year post treatment, the treatment outcomes were determined by 2 oral and maxillofacial surgeons, blinded for the treatment option. Adequate follow-up data were obtained from 290 patients. The overall success rate was 71% in the patients treated conventionally and 81% in the patients treated using the ultrasonic system. In molar teeth, the difference in success rate was statistically significant.

  15. The Effect of Canal Contamination with Saliva on Apical Sealing

    Directory of Open Access Journals (Sweden)

    S Sabaghi

    2014-08-01

    Methods: In this laboratory study, 58 human uni-root teeth were cleaned and shaped for obturation with gutta percha and sealer AH26. In the case group, specimens were contaminated with human saliva immediately before obturation, whereas the teeth in the control group were kept dry. All canals were filled by lateral condensation technique. Moreover, the teeth were placed in methylene blue dye for 3 days. Dye penetration was measured using a stereomicrosope. As a matter of fact, the study data were analyzed via utilizing t-test. Results: A significant difference was found between the two groups in regard with the apical leakage(P<0.001. The microleakage mean of dye in the dry group was 3/48mm, whereas it was 6/36mm in the saliva contaminated group. Conclusion: The study findings revealed that complete drying of canal can improve apical sealing.

  16. Transient apical dyskinesia with a pacemaker: Electrocardiographic features.

    Science.gov (United States)

    Núñez-Gil, Iván J; Feltes, Gisela I; Mejía-Rentería, Hernán D; Biagioni, Corina; De Agustín, J Alberto; Vivas, David; Fernández-Ortiz, Antonio

    2015-04-01

    Transient apical dyskinesia syndromes present features similar to acute coronary syndromes, but with normal coronary arteries and rapid complete resolution of wall motion alterations. We report the case of a 73-year-old woman who was admitted to hospital because of typical chest pain at rest after her brother's death. She had had a pacemaker implanted in 2001. Troponin levels were elevated and apical hypokinesia was shown by ventriculography and echocardiography, with normal coronary arteries. Evolving ECG alterations were observed in spite of the continued pacing rhythm. All these alterations were fully resolved after discharge. This case shows that, even in the presence of a pacemaker, evolving ECG alterations can be observed in Takotsubo syndrome.

  17. Apical ballooning-like syndrome: Hypocalcemia? What else!

    Directory of Open Access Journals (Sweden)

    Maria Accadia

    2016-01-01

    Full Text Available Apical ballooning syndrome (ABS, also known as Takotsubo or stress cardiomyopathy, is characterised by acute, transient and severe LV dysfunction, mimicking myocardial infarction; it occurs, in most cases, in the absence of obstructive coronary disease and is precipitated by severe emotional or physical stress, but many other potential triggers has been identi ed in the last years. Although the pathogenesis of ABS remains unclear, the most common mechanisms suggested are coronary vasospam and an exaggerated sympathetic activation associated to high levels of plasma cathecolamine leading to cardiotoxicity.We describe two cases of Apical Ballooning like Syndrome that were triggered by severe, acute hypocalcemia, without evidence of coronary vasospasm and with normal hematic level of cathecolamines.

  18. Aseptic multiplication of banana from excised floral apices.

    Science.gov (United States)

    Cronauer, S S; Krikorian, A D

    1985-08-01

    Most economically important bananas and plantains are large triploid seedless herbs that must be propagated vegetatively by removing small side shoots or "suckers" from the parent plant or by planting seed pieces of larger corms. Consequently, multiplication of stock material is time consuming, Recently, the rapid production of young banana plantlets suitable for use as "seed" material has been described. Vegetative shoot apices were isolated and multiplied using aseptic tissue culture techniques. Although these multiplication systems, once established, can produce thousands of plants in a relatively short period of time, their establishment necessitates the initial sacrifice of an individual specimen, which may not always be desirable or prudent should a limited parent stock be available. We describe here the production and multiplication of rooted banana plantlets from the isolation and culture of terminal floral apices.

  19. Blunt apical dissection during anatomic radical retropubic prostatectomy

    Directory of Open Access Journals (Sweden)

    Yacoub Saif

    2009-02-01

    Full Text Available Abstract Background Meticulous apical dissection during a radical prostatectomy is imperative to achieve desirable pathologic and quality of life outcomes. Findings We describe a novel technique using careful blunt dissection to better delineate the apex of the prostate, providing a simple means to potentially lessen positive surgical margins at the apex and promote better continence and erectile function in men undergoing an anatomic radical prostatectomy. Median operative time and blood loss were 190 minutes and 675 mL, respectively. Only 10 percent of the patients with positive surgical margins were found to have apical positive surgical margins. Ninety-three percent of patients reported no urinary leakage. Conclusion We believe our technique of isolating the DVC with blunt dissection and then ligating and transecting the DVC to be feasible approach that requires larger studies to truly confirm its utility.

  20. Octagonal Defects at Carbon Nanotube Junctions

    Science.gov (United States)

    Jaskólski, W.; Pelc, M.; Chico, Leonor; Ayuela, A.

    2013-01-01

    We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (EF). The reconstructed junction has only one state near EF, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system. PMID:24089604

  1. Apical ballooning-like syndrome: Hypocalcemia? What else!

    OpenAIRE

    Maria Accadia; Marianna Abitabile; Salvatore Rumolo; Scotto di Uccio Fortunato; Luigi Irace; Andrea Tuccillo; Giuseppe Mercogliano; Bernardino Tuccillo

    2016-01-01

    Apical ballooning syndrome (ABS), also known as Takotsubo or stress cardiomyopathy, is characterised by acute, transient and severe LV dysfunction, mimicking myocardial infarction; it occurs, in most cases, in the absence of obstructive coronary disease and is precipitated by severe emotional or physical stress, but many other potential triggers has been identi ed in the last years. Although the pathogenesis of ABS remains unclear, the most common mechanisms suggested are coronary vasospam an...

  2. Interplay between miRNA regulation and mechanical stress for CUC gene expression at the shoot apical meristem.

    Science.gov (United States)

    Fal, Kateryna; Landrein, Benoit; Hamant, Olivier

    2016-01-01

    The shoot apical meristem is the central organizer of plant aerial organogenesis. The molecular bases of its functions involve several cross-talks between transcription factors, hormones and microRNAs. We recently showed that the expression of the homeobox transcription factor STM is induced by mechanical perturbations, adding another layer of complexity to this regulation. Here we provide additional evidence that mechanical perturbations impact the promoter activity of CUC3, an important regulator of boundary formation at the shoot meristem. Interestingly, we did not detect such an effect for CUC1. This suggests that the robustness of expression patterns and developmental programs is controlled via a combined action of molecular factors as well as mechanical cues in the shoot apical meristem.

  3. An Apical-Membrane Chloride Channel in Human Tracheal Epithelium

    Science.gov (United States)

    Welsh, Michael J.

    1986-06-01

    The mechanism of chloride transport by airway epithelia has been of substantial interest because airway and sweat gland-duct epithelia are chloride-impermeable in cystic fibrosis. The decreased chloride permeability prevents normal secretion by the airway epithelium, thereby interfering with mucociliary clearance and contributing to the morbidity and mortality of the disease. Because chloride secretion depends on and is regulated by chloride conductance in the apical cell membrane, the patch-clamp technique was used to directly examine single-channel currents in primary cultures of human tracheal epithelium. The cells contained an anion-selective channel that was not strongly voltage-gated or regulated by calcium in cell-free patches. The channel was also blocked by analogs of carboxylic acid that decrease apical chloride conductance in intact epithelia. When attached to the cell, the channel was activated by isoproterenol, although the channel was also observed to open spontaneously. However, in some cases, the channel was only observed after the patch was excised from the cell. These results suggest that this channel is responsible for the apical chloride conductance in airway epithelia.

  4. Apical Periodontitis - Is It Accountable for Cardiovascular Diseases?

    Science.gov (United States)

    Garg, Paridhi; Chaman, Chandrakar

    2016-08-01

    The aim of this review was to assess the relationship between apical periodontitis and cardiovascular diseases and the predictive factors regarding this association. Cross sectional and observational studies have been included, which are mostly retrospective. A comprehensive search was performed in the Systematic Electronic Databases, PUBMED and MEDLINE from 1919 till September 2014. Articles were also hand searched. From 86 studies identified, all were read and 58 articles which were relevant were included in the text. Some articles were excluded because they were pertaining to periodontology and other systemic disorders. Some were solely animal studies and were thus excluded. Our results suggest an independent association between cardiovascular diseases and apical periodontitis. A causal relationship could not be established since weak parameters of risk have been assessed in the studies, population taken is difficult to compare and other confounding factors have not been ruled out. Only a more focused and better instituted scientific research can determine this association. Establishing a cause and effect relationship between apical periodontitis and cardiovascular diseases can affect the course of treatment of cardiovascular diseases. It is not only of interest from the scientific point of view but also from public health perspective.

  5. The Effect of Canal Contamination with Saliva on Apical Sealing

    Directory of Open Access Journals (Sweden)

    S Sabaghi

    2014-08-01

    Full Text Available Introduction: Root canal obturation aims at sealing the root canal system to prevent re-contamination of canal and periapical space. Presence of moisture in canal before obturation may posit a negative effect on the quality of canal sealing. Therefore, this study was conducted to investigate the effect of canal contamination with saliva on apical microleakage. Methods: In this laboratory study, 58 human uni-root teeth were cleaned and shaped for obturation with gutta percha and sealer AH26. In the case group, specimens were contaminated with human saliva immediately before obturation, whereas the teeth in the control group were kept dry. All canals were filled by lateral condensation technique. Moreover, the teeth were placed in methylene blue dye for 3 days. Dye penetration was measured using a stereomicrosope. As a matter of fact, the study data were analyzed via utilizing t-test. Results: A significant difference was found between the two groups in regard with the apical leakage(P<0.001. The microleakage mean of dye in the dry group was 3/48mm, whereas it was 6/36mm in the saliva contaminated group. Conclusion: The study findings revealed that complete drying of canal can improve apical sealing.

  6. RNG1 is a Late Marker of the Apical Polar Ring in Toxoplasma gondii

    Science.gov (United States)

    Tran, Johnson Q.; de Leon, Jessica C.; Li, Catherine; Huynh, My-Hang; Beatty, Wandy; Morrissette, Naomi S.

    2010-01-01

    The asexually proliferating stages of apicomplexan parasites cause acute symptoms of diseases such as malaria, cryptosporidiosis and toxoplasmosis. These stages are characterized by the presence of two independent microtubule organizing centers (MTOCs). Centrioles are found at the poles of the intranuclear spindle. The apical polar ring (APR), a MTOC unique to apicomplexans, organizes subpellicular microtubules which impose cell shape and apical polarity on these protozoa. Here we describe the characteristics of a novel protein that localizes to the APR of Toxoplasma gondii which we have named ring-1 (RNG1). There are related RNG1 proteins in Neospora caninum and Sarcocystis neurona but no obvious homologs in Plasmodium spp., Cryptosporidium spp. or Babesia spp. RNG1 is a small, low-complexity, detergent-insoluble protein that assembles at the APR very late in the process of daughter parasite replication. We were unable to knock-out the RNG1 gene, suggesting that its gene product is essential. Tagged RNG1 lines have also allowed us to visualize the APR during growth of Toxoplasma in the microtubule-disrupting drug oryzalin. Oryzalin inhibits nuclear division and cytokinesis although Toxoplasma growth continues, and similar to earlier observations of unchecked centriole duplication in oryzalin-treated parasites, the APR continues to duplicate during aberrant parasite growth. PMID:20658557

  7. AmotL2 disrupts apical-basal cell polarity and promotes tumour invasion.

    Science.gov (United States)

    Mojallal, Mahdi; Zheng, Yujuan; Hultin, Sara; Audebert, Stéphane; van Harn, Tanja; Johnsson, Per; Lenander, Claes; Fritz, Nicolas; Mieth, Christin; Corcoran, Martin; Lembo, Frédérique; Hallström, Marja; Hartman, Johan; Mazure, Nathalie M; Weide, Thomas; Grandér, Dan; Borg, Jean-Paul; Uhlén, Per; Holmgren, Lars

    2014-08-01

    The establishment and maintenance of apical-basal cell polarity is essential for the functionality of glandular epithelia. Cell polarity is often lost in advanced tumours correlating with acquisition of invasive and malignant properties. Despite extensive knowledge regarding the formation and maintenance of polarity, the mechanisms that deregulate polarity in metastasizing cells remain to be fully characterized. Here we show that AmotL2 expression correlates with loss of tissue architecture in tumours from human breast and colon cancer patients. We further show that hypoxic stress results in activation of c-Fos-dependent expression of AmotL2 leading to loss of polarity. c-Fos/hypoxia-induced p60 AmotL2 interacts with the Crb3 and Par3 polarity complexes retaining them in large vesicles and preventing them from reaching the apical membrane. The resulting loss of polarity potentiates the response to invasive cues in vitro and in vivo in mice. These data provide a molecular mechanism how hypoxic stress deregulates cell polarity during tumour progression.

  8. Apical transport of influenza A virus ribonucleoprotein requires Rab11-positive recycling endosome.

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    Fumitaka Momose

    Full Text Available Influenza A virus RNA genome exists as eight-segmented ribonucleoprotein complexes containing viral RNA polymerase and nucleoprotein (vRNPs. Packaging of vRNPs and virus budding take place at the apical plasma membrane (APM. However, little is known about the molecular mechanisms of apical transport of newly synthesized vRNP. Transfection of fluorescent-labeled antibody and subsequent live cell imaging revealed that punctate vRNP signals moved along microtubules rapidly but intermittently in both directions, suggestive of vesicle trafficking. Using a series of Rab family protein, we demonstrated that progeny vRNP localized to recycling endosome (RE in an active/GTP-bound Rab11-dependent manner. The vRNP interacted with Rab11 through viral RNA polymerase. The localization of vRNP to RE and subsequent accumulation to the APM were impaired by overexpression of Rab binding domains (RBD of Rab11 family interacting proteins (Rab11-FIPs. Similarly, no APM accumulation was observed by overexpression of class II Rab11-FIP mutants lacking RBD. These results suggest that the progeny vRNP makes use of Rab11-dependent RE machinery for APM trafficking.

  9. The LBD12-1 Transcription Factor Suppresses Apical Meristem Size by Repressing Argonaute 10 Expression.

    Science.gov (United States)

    Ma, Weiwei; Wu, Fuqing; Sheng, Peike; Wang, Xiaole; Zhang, Zhe; Zhou, Kunneng; Zhang, Huan; Hu, Jinlong; Lin, Qibin; Cheng, Zhijun; Wang, Jiulin; Zhu, Shanshan; Zhang, Xin; Guo, Xiuping; Wang, Haiyang; Wu, Chuanyin; Zhai, Huqu; Wan, Jianmin

    2017-01-01

    The shoot apical meristem (SAM) consists of a population of multipotent cells that generates all aerial structures and regenerates itself. SAM maintenance and lateral organ development are regulated by several complex signaling pathways, in which the Argonaute gene-mediated pathway plays a key role. One Argonaute gene, AGO10, functions as a microRNA locker that attenuates miR165/166 activity and positively regulates shoot apical meristem development, but little is known about when and how AGO10 is regulated at the transcriptional level. In this work, we showed that transgenic rice plants overexpressing LBD12-1, an LBD family transcription factor, exhibited stunted growth, twisted leaves, abnormal anthers, and reduced SAM size. Further research revealed that LBD12-1 directly binds to the promoter region and represses the expression of AGO10. Overexpression of AGO10 in an LBD12-1 overexpression background rescued the growth defect phenotype of LBD12-1-overexpressing plants. The expression of LBD12-1 and its binding ability to the AGO10 promoter is induced by stress. lbd12-1 loss-of-function mutants showed similar phenotypes and SAM size to the wild type under normal conditions, but lbd12-1 had a larger SAM under salt stress. Our findings provide novel insights into the regulatory mechanism of AGO10 by which SAM size is controlled under stress conditions. © 2017 American Society of Plant Biologists. All Rights Reserved.

  10. Mouse sperm acquire a new structure on the apical hook during epididymal maturation

    Institute of Scientific and Technical Information of China (English)

    Yi-Wen Lin; Tzu-Han Hsu; Pauline H Yen

    2013-01-01

    Spermatozoa emerging from the testis undergo a maturation process in the epididymis during which they change morphologically,biochemically and physiologically to gain motility and the ability to fertilize ova.We examined mouse epididymal sperm with immunostaining and transmission electron microscopy (EM) and identified a previously unknown structure on the apical hook.The structure has a coiled configuration around 11 nm in thickness and is present at the tip of each corner of the triangular-rod shaped perforatorium.Surveying sperm isolated from various regions of the epididymis indicated that mouse sperm acquire the hook rim (HR) structure during its passage through the proximal two-thirds of the caput epididymidis.The structure withstands vigorous sonication and harsh chemical treatments and remains intact after the acrosome reaction.Its location and sturdiness suggest a function in protecting the apical hook from mechanical wear during fertilization.Our EM images of epididymal sperm also revealed additional novel structures as well as lateral asymmetry of the sperm head,indicating that mouse sperm head has a structure more complex than previously recognized.

  11. AKAP220 manages apical actin networks that coordinate aquaporin-2 location and renal water reabsorption.

    Science.gov (United States)

    Whiting, Jennifer L; Ogier, Leah; Forbush, Katherine A; Bucko, Paula; Gopalan, Janani; Seternes, Ole-Morten; Langeberg, Lorene K; Scott, John D

    2016-07-26

    Filtration through the kidney eliminates toxins, manages electrolyte balance, and controls water homeostasis. Reabsorption of water from the luminal fluid of the nephron occurs through aquaporin-2 (AQP2) water pores in principal cells that line the kidney-collecting duct. This vital process is impeded by formation of an "actin barrier" that obstructs the passive transit of AQP2 to the plasma membrane. Bidirectional control of AQP2 trafficking is managed by hormones and signaling enzymes. We have discovered that vasopressin-independent facets of this homeostatic mechanism are under the control of A-Kinase Anchoring Protein 220 (AKAP220; product of the Akap11 gene). CRISPR/Cas9 gene editing and imaging approaches show that loss of AKAP220 disrupts apical actin networks in organoid cultures. Similar defects are evident in tissue sections from AKAP220-KO mice. Biochemical analysis of AKAP220-null kidney extracts detected reduced levels of active RhoA GTPase, a well-known modulator of the actin cytoskeleton. Fluorescent imaging of kidney sections from these genetically modified mice revealed that RhoA and AQP2 accumulate at the apical surface of the collecting duct. Consequently, these animals are unable to appropriately dilute urine in response to overhydration. We propose that membrane-proximal signaling complexes constrained by AKAP220 impact the actin barrier dynamics and AQP2 trafficking to ensure water homeostasis.

  12. DNA gridiron nanostructures based on four-arm junctions.

    Science.gov (United States)

    Han, Dongran; Pal, Suchetan; Yang, Yang; Jiang, Shuoxing; Nangreave, Jeanette; Liu, Yan; Yan, Hao

    2013-03-22

    Engineering wireframe architectures and scaffolds of increasing complexity is one of the important challenges in nanotechnology. We present a design strategy to create gridiron-like DNA structures. A series of four-arm junctions are used as vertices within a network of double-helical DNA fragments. Deliberate distortion of the junctions from their most relaxed conformations ensures that a scaffold strand can traverse through individual vertices in multiple directions. DNA gridirons were assembled, ranging from two-dimensional arrays with reconfigurability to multilayer and three-dimensional structures and curved objects.

  13. Modulation of Tight Junction Structure and Function by Kinases and Phosphatases Targeting Occludin

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    Max Johannes Dörfel

    2012-01-01

    Full Text Available Tight junctions (TJs typically represent the most apical contacts in epithelial and endothelial cell layers where they play an essential role in the separation of extracellular or luminal spaces from underlying tissues in the body. Depending on the protein composition, TJs define the barrier characteristics and in addition maintain cell polarity. Two major families of integral membrane proteins form the typical TJ strand network, the tight junction-associated MARVEL protein (TAMP family members occludin, tricellulin, and MarvelD3 as well as a specific set of claudins. Occludin was the first identified member of these tetraspanins and is now widely accepted as a regulator of TJ assembly and function. Therefore, occludin itself has to be tightly regulated. Phosphorylation of occludin appears to be of central importance in this context. Here we want to summarize current knowledge on the kinases and phosphatases directly modifying occludin, and their role in the regulation of TJ structure, function, and dynamics.

  14. Modelling of Dual-Junction Solar Cells including Tunnel Junction

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    Abdelaziz Amine

    2013-01-01

    Full Text Available Monolithically stacked multijunction solar cells based on III–V semiconductors materials are the state-of-art of approach for high efficiency photovoltaic energy conversion, in particular for space applications. The individual subcells of the multi-junction structure are interconnected via tunnel diodes which must be optically transparent and connect the component cells with a minimum electrical resistance. The quality of these diodes determines the output performance of the solar cell. The purpose of this work is to contribute to the investigation of the tunnel electrical resistance of such a multi-junction cell through the analysis of the current-voltage (J-V characteristics under illumination. Our approach is based on an equivalent circuit model of a diode for each subcell. We examine the effect of tunnel resistance on the performance of a multi-junction cell using minimization of the least squares technique.

  15. A modular LHC built on the DNA three-way junction.

    Science.gov (United States)

    Probst, Markus; Langenegger, Simon M; Häner, Robert

    2014-01-07

    A light-harvesting complex composed of a π-stacked multichromophoric array in a DNA three-way junction is described. The modular design allows for a ready exchange of non-covalently attached energy acceptors.

  16. Dielectric properties of biological tissues in which cells are connected by communicating junctions

    Science.gov (United States)

    Asami, Koji

    2007-06-01

    The frequency dependence of the complex permittivity of biological tissues has been simulated using a simple model that is a cubic array of spherical cells in a parallel plate capacitor. The cells are connected by two types of communicating junctions: one is a membrane-lined channel for plasmodesmata in plant tissues, and the other is a conducting patch of adjoining plasma membranes for gap junctions in animal tissues. Both junctions provided similar effects on the dielectric properties of the tissue model. The model without junction showed a dielectric relaxation (called β-dispersion) that was expected from an interfacial polarization theory for a concentrated suspension of spherical cells. The dielectric relaxation was the same as that of the model in which neighbouring cells were connected by junctions perpendicular to the applied electric field. When neighbouring cells were connected by junctions parallel to the applied electric field or in all directions, a dielectric relaxation appeared at a lower frequency side in addition to the β-dispersion, corresponding to the so called α-dispersion. When junctions were randomly introduced at varied probabilities Pj, the low-frequency (LF) relaxation curve became broader, especially at Pj of 0.2-0.5, and its intensity was proportional to Pj up to 0.7. The intensity and the characteristic frequency of the LF relaxation both decreased with decreasing junction conductance. The simulations indicate that communicating junctions are important for understanding the LF dielectric relaxation in tissues.

  17. Occurrence of the Transition of Apical Architecture and Expression Patterns of Related Genes during Conversion of Apical Meristem Identity in G2 Pea

    Institute of Scientific and Technical Information of China (English)

    Da-Yong Wang; Qing Li; Ke-Ming Cui; Yu-Xian Zhu

    2009-01-01

    G2 pea exhibits an apical senescence delaying phenotype under short-day (SD) conditions; however, the structural basis for its apical development is still largely unknown. In the present study, the apical meristem of SD-grown G2 pea plants underwent a transition from vegetative to indeterminate inflorescence meristem, but the apical meristem of long-day (LD)-grown G2 pea plants would be further converted to determinate floral meristem. Both SD signal and GA3 treatment enhanced expression of the putative calcium transporter PPF1, and pea homologs of TFL1 (LF and DET), whereas LD signal suppressed their expression at 60 d post-flowering compared with those at 40 d post-flowering. Both PPF1 and LF expressed at the vegetative and reproductive phases in SD-grown apical buds, but floral initiation obviously increased the expression level of PPF1 compared with the unchanged expression level of LF from 40 to 60 d post-flowering. In addition, although the floral initiation significantly enhanced the expression levels of PPF1 and DET, DET was mainly expressed after floral initiation in SD-grown apical buds. Therefore, the main structural difference between LD- and SD-grown apical meristem in G2 pea lies in whether their apical indeterminate inflorescence medstem could be converted to the determinate structure.

  18. Evaluation of the reinforcement effect on teeth with different apical foramen diameters of retrograde or orthograde MTA application with internal matrix

    Directory of Open Access Journals (Sweden)

    Emre Bayram

    2016-01-01

    Full Text Available OBJECTIVE: The aim of this study was to determine the effect of the apical foramen diameter and different application methods of Mineral Trioxide Aggregate (MTA on the fracture resistance of simulated immature teeth using a Universal Testing Machine. MATERIALS AND METHOD: Ninety extracted human teeth were used for the fracture resistance test. The apical foramen was prepared to a diameter of 1.0 mm or 1.4 mm to simulate the open apex of immature teeth. MTA was mixed according to manufacturer's recommendations and placed into the root canals with different apical foramen diameter by four different root filling techniques: retrograde, two-phased orthograde, and ortograde with or without internal matrix. Prepared roots were marked 2 mm below the cemento-enamel junction and embedded in transparent acrylic resin in cylinder moulds. Vertical force was applied along the long axis of the tooth at a speed of 5 mm/min, and the maximum resistance to fracture for each tooth was determined in Newton. A software package was used for the statistical analysis. The data were analyzed by using one-way ANOVA and post-hoc Tukey tests. RESULTS: A statistically significant difference could not be observed between the groups (p>0.05 whereas statistically significant differences were found between the test groups and the control groups (p<0.05. CONCLUSION: There was no significant difference between different vertical root filling techniques in increasing the fracture strength of the teeth. The diameter of the apical foramen did not have a significant effect on the fracture resistance.

  19. Evaluation of Apical Sealing Ability of a Dentin Bonding Agent and Epoxy Resin used as Root Canal Sealer - An In Vitro Dye Leakage Study

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    Srinidhi Surya Raghavendra

    2012-01-01

    Full Text Available Objectives: Total obliteration of the canal space and perfect sealing of the apical foramen with an inert, dimensionally stable and biologically compatible material are the goals for successful endodontic treatment. A microscopic layer of debris is formed during bio-mechanical preparation of the canal called Smear layer. This interferes with adhesion and penetration of canal sealers and its removal is necessary. Dentin bonding agents have been studied extensively for their adhesive properties in restorative dentistry and recently as root canal sealers. Microleakage studies of their sealing abilities are few. Materials and Methods: This study evaluated sealing efficacy of a dentin bonding agent when used as root canal sealer along with AH26, an epoxy resin sealer and the effect of the smear layer on the sealing ability. 60 extracted maxillary anterior teeth were taken, sectioned at the Cemento enamel junction, cleaned and shaped with 2% K files. They were divided into 4 groups, GroupsAandBwithoutEDTApre-treatment and GroupsCandDwithEDTApre-treatment. GroupsAandCwere obturated withAH26 and Groups B and D were obturated with dentin bonding agent Polibond andAH26 with gutta percha and lateral condensation method. Apical dye penetration was measured using 2% Methylene Blue and evaluated with stereo microscope. Results were tabulated and statistical analysis done. Results: The chemically cured bonding agent Polibond used with AH26 showed significantly less apical leakage when smear layer was removed before obturation. Conclusion: Use of dentin bonding agents and resin sealers in root canal obturations achieves effective apical sealing when used with gutta percha. This improves the success of endodontic therapy.

  20. Transcriptome profiling for discovery of genes involved in shoot apical meristem and flower development

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    Vikash K. Singh

    2014-12-01

    Full Text Available Flower development is one of the major developmental processes that governs seed setting in angiosperms. However, little is known about the molecular mechanisms underlying flower development in legumes. Employing RNA-seq for various stages of flower development and few vegetative tissues in chickpea, we identified differentially expressed genes in flower tissues/stages in comparison to vegetative tissues, which are related to various biological processes and molecular functions during flower development. Here, we provide details of experimental methods, RNA-seq data (available at Gene Expression Omnibus database under GSE42679 and analysis pipeline published by Singh and colleagues in the Plant Biotechnology Journal (Singh et al., 2013, along with additional analysis for discovery of genes involved in shoot apical meristem (SAM development. Our data provide a resource for exploring the complex molecular mechanisms underlying SAM and flower development and identification of gene targets for functional and applied genomics in legumes.

  1. Gap junctions - guards of excitability.

    Science.gov (United States)

    Stroemlund, Line Waring; Jensen, Christa Funch; Qvortrup, Klaus; Delmar, Mario; Nielsen, Morten Schak

    2015-06-01

    Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances of the heart and focuses on the role of the gap junctional protein connexin 43 (Cx43). Current evidence shows that Cx43 plays a crucial role in organizing microtubules at the intercalated disc and thereby regulating the trafficking of the cardiac sodium channel NaV1.5 to the membrane.

  2. Grainy head promotes expression of septate junction proteins and influences epithelial morphogenesis.

    Science.gov (United States)

    Narasimha, Maithreyi; Uv, Anne; Krejci, Alena; Brown, Nicholas H; Bray, Sarah J

    2008-03-15

    Transcription factors of the Grainy head (Grh) family are required in epithelia to generate the impermeable apical layer that protects against the external environment. This function is conserved in vertebrates and invertebrates, despite the differing molecular composition of the protective barrier. Epithelial cells also have junctions that create a paracellular diffusion barrier (tight or septate junctions). To examine whether Grh has a role in regulating such characteristics, we used an epidermal layer in the Drosophila embryo that has no endogenous Grh and lacks septate junctions, the amnioserosa. Expression of Grh in the amnioserosa caused severe defects in dorsal closure, a process similar to wound closure, and induced robust expression of the septate junction proteins Coracle, Fasciclin 3 and Sinuous. Grh-binding sites are present within the genes encoding these proteins, consistent with them being direct targets. Removal of Grh from imaginal disc cells caused a reduction in Fasciclin 3 and Coracle levels, suggesting that Grh normally fine tunes their epithelial expression and hence contributes to barrier properties. The fact that ectopic Grh arrests dorsal closure also suggests that this dynamic process relies on epithelia having distinct adhesive properties conferred by differential deployment of Grh.

  3. SEM investigation of Er:YAG laser apical preparation

    Science.gov (United States)

    Bǎlǎbuc, Cosmin; Todea, Carmen; Locovei, Cosmin; RǎduÅ£ǎ, Aurel

    2016-03-01

    Endodontic surgery involves the incision and flap elevation, the access to the root tip, its resection, the cavity retrograde preparation and filling it with biocompatible material that provides a good seal of the apex[1]. Apicoectomy is compulsory in endodontic surgery. The final stage involves the root retropreparation and the carrying out of the retrograde obturation. In order to perform the retrograde preparation the endodontist can use various tools such as lowspeed conventional handpieces, sonic and ultrasonic equipment. The ideal depth of the preparation should be 3 mm, exceeding this value may affect the long-term success of the obturation [2]. Resection at the depth of 3 mm reduces apical ramifications by 98% and lateral root canals by 93%. The ultrasonic retropreparation has numerous advantages compared to the dental drill. Firstly, the cavity will be in the axis of the tooth which implies a minimum destruction of the root canal morphology. The preparations are precise, and the cutting pattern is perpendicular to the long axis of the root, the advantage being the reduction in the number of dentinal tubules exposed at the resected area [3]. Therefore, the retrograde filling is the procedure when an inert and non-toxic material is compacted in the apically created cavity.[4,5]. The Er:YAG laser is the most common wavelength indicated for dental hard tissue preparation. Its natural selectivity offers a significant advantage compared to the conventional hard tissue preparation [6-9].The purpose of this in vitro study was to investigate the quality of Er:YAG laser apical third preparation using Scanning Electron Microscopy (SEM), in comparison with the conventional ultrasonic method.

  4. Bacterial communities associated with apical periodontitis and dental implant failure

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    Simon Dingsdag

    2016-11-01

    Full Text Available Background: Previously, we demonstrated that bacteria reside in apparently healed alveolar bone, using culture and Sanger sequencing techniques. Bacteria in apparently healed alveolar bone may have a role in peri-implantitis and dental implant failure. Objective: To compare bacterial communities associated with apical periodontitis, those colonising a failed implant and alveolar bone with reference biofilm samples from healthy teeth. Methods and results: The study consisted of 196 samples collected from 40 patients undergoing routine dental implant insertion or rehabilitation. The bacterial 16S ribosomal DNA sequences were amplified. Samples yielding sufficient polymerase chain reaction product for further molecular analyses were subjected to terminal restriction fragment length polymorphism (T-RFLP; 31 samples and next generation DNA sequencing (454 GS FLX Titanium; 8 samples. T-RFLP analysis revealed that the bacterial communities in diseased tissues were more similar to each other (p<0.049 than those from the healthy reference samples. Next generation sequencing detected 13 bacterial phyla and 373 putative bacterial species, revealing an increased abundance of Gram-negative [Prevotella, Fusobacterium (p<0.004, Treponema, Veillonellaceae, TG5 (Synergistetes] bacteria and a decreased abundance of Gram-positive [(Actinomyces, Corynebacterium (p<0.008] bacteria in the diseased tissue samples (n=5 relative to reference supragingival healthy samples (n=3. Conclusion: Increased abundances of Prevotella, Fusobacterium and TG5 (Synergistetes were associated with apical periodontitis and a failed implant. A larger sample set is needed to confirm these trends and to better define the processes of bacterial pathogenesis in implant failure and apical periodontitis. The application of combined culture-based, microscopic and molecular technique-based approaches is suggested for future studies.

  5. Apical Na+ permeability of frog skin during serosal Cl- replacement.

    Science.gov (United States)

    Leibowich, S; DeLong, J; Civan, M M

    1988-05-01

    Gluconate substitution for serosal Cl- reduces the transepithelial short-circuit current (Isc) and depolarizes short-circuited frog skins. These effects could result either from inhibition of basolateral K+ conductance, or from two actions to inhibit both apical Na+ permeability (PapNa) and basolateral pump activity. We have addressed this question by studying whole-and split-thickness frog skins. Intracellular Na+ concentration (CcNa) and PapNa have been monitored by measuring the current-voltage relationship for apical Na+ entry. This analysis was conducted by applying trains of voltage pulses, with pulse durations of 16 to 32 msec. Estimates of PapNa and CcNa were not detectably dependent on pulse duration over the range 16 to 80 msec. Serosal Cl- replacement uniformly depolarized short-circuited tissues. The depolarization was associated with inhibition of Isc across each split skin, but only occasionally across the whole-thickness preparations. This difference may reflect the better ionic exchange between the bulk medium and the extracellular fluid in contact with the basolateral membranes, following removal of the underlying dermis in the split-skin preparations. PapNa was either unchanged or increased, and CcNa either unchanged or reduced after the anionic replacement. These data are incompatible with the concept that serosal Cl- replacement inhibits PapNa and Na,K-pump activity. Gluconate substitution likely reduces cell volume, triggering inhibition of the basolateral K+ channels, consistent with the data and conclusions of S.A. Lewis, A.G. Butt, M.J. Bowler, J.P. Leader and A.D.C. Macknight (J. Membrane Biol. 83:119-137, 1985) for toad bladder. The resulting depolarization reduces the electrical force favoring apical Na+ entry. The volume-conductance coupling serves to conserve volume by reducing K+ solute loss. Its molecular basis remains to be identified.

  6. Reparación apical y periapical post tratamiento endodontico.

    OpenAIRE

    Altare, Lia

    2010-01-01

    El propósito de este trabajo es describir el proceso reparativo apical y periapical post tratamiento endodóntico , los mecanismos y sistemas celulares involucrados ,dentro del campo de la Endodoncia Biomolecular.Una nueva era de conocimientos invaden a la Endodoncia Moderna dado por la Ingeniería Tisular Endodóntica desde donde se plantean alternativas terapéuticas .El análisis de la capacidad biológica reparativa de cada paciente demuestra una variabilidad en la respuesta frente a un tratami...

  7. Control over Rectification in Supramolecular Tunneling Junctions

    NARCIS (Netherlands)

    Wimbush, K.S.; Wimbush, Kim S.; Reus, William F.; van der Wiel, Wilfred Gerard; Reinhoudt, David; Whitesides, George M.; Nijhuis, C.A.; Velders, Aldrik

    2010-01-01

    In complete control: The magnitude of current rectification in well-defined supramolecular tunneling junctions can be controlled by changing the terminal functionality (red spheres) of dendrimers (gray spheres) immobilized on a supramolecular platform (see picture). Junctions containing biferrocene

  8. Nano-Molecular Junctions on STM Tips

    Institute of Scientific and Technical Information of China (English)

    Chun Huang∗; Jianshu Yang

    2011-01-01

    We present a technique for building metal-organic-metal junctions, which contain ten or fewer conjugated molecules between each of such junction, and the investigations of the I-V response of these junctions. The junctions are made by self assembling thiolated molecules onto gold coated tips for use in scanning tunneling microscopy. We show that this easy technique probes the qualitative properties of the molecules. Current-voltage characteristics of a Tour wire and a new molecular rectifier are presented.

  9. Nano-Molecular Junctions on STM Tips

    Institute of Scientific and Technical Information of China (English)

    Chun Huang; Jianshu Yang

    2011-01-01

    We present a technique for building metal-organic-metal junctions, which contain ten or fewer conjugated molecules between each of such junction, and the investigations of the I-V response of these junctions.The junctions are made by self assembling thiolated molecules onto gold coated tips for use in scanning tunneling microscopy. We show that this easy technique probes the qualitative properties of the molecules. Currentvoltage characteristics of a Tour wire and a new molecular rectifier are presented.

  10. Current noise in tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Frey, Moritz; Grabert, Hermann [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104, Freiburg (Germany)

    2017-06-15

    We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc bias...

  12. Atomically thin lateral p-n junction photodetector with large effective detection area

    Science.gov (United States)

    Xu, Zai-Quan; Zhang, Yupeng; Wang, Ziyu; Shen, Yuting; Huang, Wenchao; Xia, Xue; Yu, Wenzhi; Xue, Yunzhou; Sun, Litao; Zheng, Changxi; Lu, Yuerui; Liao, Lei; Bao, Qiaoliang

    2016-12-01

    The widely used photodetector design based on atomically thin transition metal dichalcogenides (TMDs) has a lateral metal-TMD-metal junction with a fairly small, line shape photoresponsive active area at the TMD-electrode interface. Here, we report a highly efficient photodetector with extremely large photoresponsive active area based on a lateral junction of monolayer-bilayer WSe2. Impressively, the separation of the electron-hole pairs (excitons) extends onto the whole 1L-2L WSe2 junction surface. The responsivity of the WSe2 junction photodetector is over 3200 times higher than that of a monolayer WSe2 device and leads to a highest external quantum efficiency of 256% due to the efficient carrier extraction. Unlike the TMD p-n junctions modulated by dual gates or localized doping, which require complex fabrication procedures, our study establishes a simple, controllable, and scalable method to improve the photodetection performance by maximizing the active area for current generation.

  13. Pulp revascularization of immature dog teeth with apical periodontitis.

    Science.gov (United States)

    Thibodeau, Blayne; Teixeira, Fabricio; Yamauchi, Mitsuo; Caplan, Daniel J; Trope, Martin

    2007-06-01

    This study examined the ability of a collagen solution to aid revascularization of necrotic-infected root canals in immature dog teeth. Sixty immature teeth from 6 dogs were infected, disinfected, and randomized into experimental groups: 1: no further treatment; 2: blood in canal; 3: collagen solution in canal, 4: collagen solution + blood, and 5: negative controls (left for natural development). Uncorrected chi-square analysis of radiographic results showed no statistical differences (p >or= 0.05) between experimental groups regarding healing of radiolucencies but a borderline statistical difference (p = 0.058) for group 1 versus group 4 for radicular thickening. Group 2 showed significantly more apical closure than group 1 (p = 0.03) and a borderline statistical difference (p = 0.051) for group 3 versus group 1. Uncorrected chi-square analysis revealed that there were no statistical differences between experimental groups for histological results. However, some roots in each of groups 1 to 4 (previously infected) showed positive histologic outcomes (thickened walls in 43.9%, apical closure in 54.9%, and new luminal tissue in 29.3%). Revascularization of disinfected immature dog root canal systems is possible.

  14. Ontogeny of the Maize Shoot Apical Meristem[W][OA

    Science.gov (United States)

    Takacs, Elizabeth M.; Li, Jie; Du, Chuanlong; Ponnala, Lalit; Janick-Buckner, Diane; Yu, Jianming; Muehlbauer, Gary J.; Schnable, Patrick S.; Timmermans, Marja C.P.; Sun, Qi; Nettleton, Dan; Scanlon, Michael J.

    2012-01-01

    The maize (Zea mays) shoot apical meristem (SAM) arises early in embryogenesis and functions during stem cell maintenance and organogenesis to generate all the aboveground organs of the plant. Despite its integral role in maize shoot development, little is known about the molecular mechanisms of SAM initiation. Laser microdissection of apical domains from developing maize embryos and seedlings was combined with RNA sequencing for transcriptomic analyses of SAM ontogeny. Molecular markers of key events during maize embryogenesis are described, and comprehensive transcriptional data from six stages in maize shoot development are generated. Transcriptomic profiling before and after SAM initiation indicates that organogenesis precedes stem cell maintenance in maize; analyses of the first three lateral organs elaborated from maize embryos provides insight into their homology and to the identity of the single maize cotyledon. Compared with the newly initiated SAM, the mature SAM is enriched for transcripts that function in transcriptional regulation, hormonal signaling, and transport. Comparisons of shoot meristems initiating juvenile leaves, adult leaves, and husk leaves illustrate differences in phase-specific (juvenile versus adult) and meristem-specific (SAM versus lateral meristem) transcript accumulation during maize shoot development. This study provides insight into the molecular genetics of SAM initiation and function in maize. PMID:22911570

  15. Stability of large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

    The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

  16. Soliton bunching in annular Josephson junctions

    DEFF Research Database (Denmark)

    Vernik, I.V; Lazarides, Nickos; Sørensen, Mads Peter

    1996-01-01

    By studying soliton (fluxon) motion in long annular Josephson junctions it is possible to avoid the influence of the boundaries and soliton-soliton collisions present in linear junctions. A new experimental design consisting of a niobium coil placed on top of an annular junction has been used...

  17. Long Range Magnetic Interaction between Josephson Junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

    1995-01-01

    A new model for magnetic coupling between long Josephson junctions is proposed. The coupling mechanism is a result of the magnetic fields outside the junctions and is consequently effective over long distances between junctions. We give specific expressions for the form and magnitude of the inter...

  18. Dynamics of pi-junction interferometer circuits

    DEFF Research Database (Denmark)

    Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.;

    2002-01-01

    The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current...

  19. Dynamics of pi-junction interferometer circuits

    DEFF Research Database (Denmark)

    Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.

    2002-01-01

    The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current...

  20. Evidence for a hopping mechanism in metal|single molecule|metal junctions involving conjugated metal–terpyridyl complexes; potential-dependent conductances of complexes [M(pyterpy)2]2+(M = Co and Fe; pyterpy = 4′-(pyridin-4-yl)-2,2′:6′,2′′-terpyridine) in ionic liquid

    DEFF Research Database (Denmark)

    Chappell, Sarah; Brooke, Carly; Nichols, Richard John;

    2016-01-01

    Extensive studies of various families of conjugated molecules in metal|molecule|metal junctions suggest that the mechanism of conductance is usually tunnelling for molecular lengths < ca. 4 nm, and that for longer molecules, coherence is lost as a hopping element becomes more significant. In this...

  1. Protein kinase a dependent phosphorylation of apical membrane antigen 1 plays an important role in erythrocyte invasion by the malaria parasite.

    Directory of Open Access Journals (Sweden)

    Kerstin Leykauf

    2010-06-01

    Full Text Available Apicomplexan parasites are obligate intracellular parasites that infect a variety of hosts, causing significant diseases in livestock and humans. The invasive forms of the parasites invade their host cells by gliding motility, an active process driven by parasite adhesion proteins and molecular motors. A crucial point during host cell invasion is the formation of a ring-shaped area of intimate contact between the parasite and the host known as a tight junction. As the invasive zoite propels itself into the host-cell, the junction moves down the length of the parasite. This process must be tightly regulated and signalling is likely to play a role in this event. One crucial protein for tight-junction formation is the apical membrane antigen 1 (AMA1. Here we have investigated the phosphorylation status of this key player in the invasion process in the human malaria parasite Plasmodium falciparum. We show that the cytoplasmic tail of P. falciparum AMA1 is phosphorylated at serine 610. We provide evidence that the enzyme responsible for serine 610 phosphorylation is the cAMP regulated protein kinase A (PfPKA. Importantly, mutation of AMA1 serine 610 to alanine abrogates phosphorylation of AMA1 in vivo and dramatically impedes invasion. In addition to shedding unexpected new light on AMA1 function, this work represents the first time PKA has been implicated in merozoite invasion.

  2. Modulation of endocytic trafficking and apical stability of CFTR in primary human airway epithelial cultures

    Science.gov (United States)

    Cholon, Deborah M.; O'Neal, Wanda K.; Randell, Scott H.; Riordan, John R.

    2010-01-01

    CFTR is a highly regulated apical chloride channel of epithelial cells that is mutated in cystic fibrosis (CF). In this study, we characterized the apical stability and intracellular trafficking of wild-type and mutant CFTR in its native environment, i.e., highly differentiated primary human airway epithelial (HAE) cultures. We labeled the apical pool of CFTR and subsequently visualized the protein in intracellular compartments. CFTR moved from the apical surface to endosomes and then efficiently recycled back to the surface. CFTR endocytosis occurred more slowly in polarized than in nonpolarized HAE cells or in a polarized epithelial cell line. The most common mutation in CF, ΔF508 CFTR, was rescued from endoplasmic reticulum retention by low-temperature incubation but transited from the apical membrane to endocytic compartments more rapidly and recycled less efficiently than wild-type CFTR. Incubation with small-molecule correctors resulted in ΔF508 CFTR at the apical membrane but did not restore apical stability. To stabilize the mutant protein at the apical membrane, we found that the dynamin inhibitor Dynasore and the cholesterol-extracting agent cyclodextrin dramatically reduced internalization of ΔF508, whereas the proteasomal inhibitor MG-132 completely blocked endocytosis of ΔF508. On examination of intrinsic properties of CFTR that may affect its apical stability, we found that N-linked oligosaccharides were not necessary for transport to the apical membrane but were required for efficient apical recycling and, therefore, influenced the turnover of surface CFTR. Thus apical stability of CFTR in its native environment is affected by properties of the protein and modulation of endocytic trafficking. PMID:20008117

  3. Roles of gap junctions, connexins and pannexins in epilepsy

    Directory of Open Access Journals (Sweden)

    Shanthini eMylvaganam

    2014-05-01

    Full Text Available Enhanced gap junctional communication (GJC between neurons is considered a major factor underlying the neuronal synchrony driving seizure activity. In addition, the hippocampal sharp wave ripple complexes, associated with learning and seizures, are diminished by GJC blocking agents. Although gap junctional blocking drugs inhibit experimental seizures, they all have other nonspecific actions. Besides interneuronal GJC between dendrites, inter-axonal and inter-glial GJC is also considered important for seizure generation. Interestingly, in most studies of cerebral tissue from animal seizure models and from human patients with epilepsy, there is up-regulation of glial, but not neuronal gap junctional mRNA and protein. Significant changes in the expression and post-translational modification of the astrocytic connexin Cx43, and Panx1 were observed in an in vitro Co++ seizure model, further supporting a role for glia in seizure-genesis, although the reasons for this remain unclear. Further suggesting an involvement of astrocytic GJC in epilepsy, is the fact that the expression of astrocytic Cx mRNAs (Cxs 30 and 43 is several fold higher than that of neuronal Cx mRNAs (Cxs 36 and 45, and the number of glial cells outnumber neuronal cells in mammalian hippocampal and cortical tissue. Pannexin expression is also increased in both animal and human epileptic tissues. Specific Cx43 mimetic peptides, Gap 27 and SLS, inhibit the docking of astrocytic connexin Cx43 proteins from forming intercellular gap junctions, diminishing spontaneous seizures. Besides GJs, Cx membrane hemichannels in glia and Panx membrane channels in neurons and glia are also inhibited by gap junctional pharmacological blockers. Although there is no doubt that connexin-based gap junctions and hemichannels, and pannexin-based membrane channels are related to epilepsy, the specific details of how they are involved and how we can modulate their function for therapeutic purposes remain to

  4. Definitions of apical vaginal support loss: a systematic review.

    Science.gov (United States)

    Meister, Melanie R L; Sutcliffe, Siobhan; Lowder, Jerry L

    2017-03-01

    We sought to identify and summarize definitions of apical support loss utilized for inclusion, success, and failure in surgical trials for treatment of apical vaginal prolapse. Pelvic organ prolapse is a common condition affecting more than 3 million women in the US, and the prevalence is increasing. Prolapse may occur in the anterior compartment, posterior compartment or at the apex. Apical support is considered paramount to overall female pelvic organ support, yet apical support loss is often underrecognized and there are no guidelines for when an apical support procedure should be performed or incorporated into a procedure designed to address prolapse. A systematic literature search was performed in 8 search engines: PubMed 1946-, Embase 1947-, Cochrane Database of Systematic Reviews, Cochrane Database of Abstracts of Review Effects, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Proquest Dissertations and Theses, and FirstSearch Proceedings, using key words for apical pelvic organ prolapse and apical suspension procedures through April 2016. Searches were limited to human beings using human filters and articles published in English. Study authors (M.R.L.M., J.L.L.) independently reviewed publications for inclusion based on predefined variables. Articles were eligible for inclusion if they satisfied any of the following criteria: (1) apical support loss was an inclusion criterion in the original study, (2) apical support loss was a surgical indication, or (3) an apical support procedure was performed as part of the primary surgery. A total of 4469 publications were identified. After review, 35 articles were included in the analysis. Prolapse-related inclusion criteria were: (1) apical prolapse (n = 20, 57.1%); (2) overall prolapse (n = 8, 22.8%); or (3) both (n = 6, 17.1%). Definitions of apical prolapse (relative to the hymen) included: (1) apical prolapse >-1 cm (n = 13, 50.0%); (2) apical prolapse >+1 cm (n = 7, 26.9%); (3) apical

  5. Permanent junctional reciprocating tachycardia in a dog.

    Science.gov (United States)

    Santilli, Roberto A; Santos, Luis F N; Perego, Manuela

    2013-09-01

    A 5-year-old male English Bulldog was presented with a 1-year history of paroxysmal supraventricular tachycardia (SVT) partially responsive to amiodarone. At admission the surface ECG showed sustained runs of a narrow QRS complex tachycardia, with a ventricular cycle length (R-R interval) of 260 ms, alternating with periods of sinus rhythm. Endocardial mapping identified the electrogenic mechanism of the SVT as a circus movement tachycardia with retrograde and decremental conduction along a concealed postero-septal atrioventricular pathway (AP) and anterograde conduction along the atrioventricular node. These characteristics were indicative of a permanent junctional reciprocating tachycardia (PJRT). Radiofrequency catheter ablation of the AP successfully terminated the PJRT, with no recurrence of tachycardia on Holter monitoring at 12 months follow-up.

  6. Development, characterization, and applications of high temperature superconductor nanobridge Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, J.R.; Tigges, C.P.; Hietala, V.M.; Plut, T.A. [Sandia National Labs., Albuquerque, NM (United States); Martens, J.S.; Char, K.; Johansson, M.E. [Conductus, Inc., Sunnyvale, CA (United States)

    1994-03-01

    A well-controlled, high-yield Josephson junction process in high temperature superconductors (HTS) is necessary for the demonstration of ultra-high-speed devices and circuits which exceed the capabilities of conventional electronics. The authors developed nanobridge Josephson junctions in high quality thin-film YBaCuO with dimensions below 100 nm fabricated using electron-beam nanolithography. They characterized this Josephson junction technology for process yield, junction parameter uniformity, and overall applicability for use in high-performance circuits. To facilitate the determination of junction parameters, they developed a measurement technique based on spectral analysis in the range of 90--160 GHz of phase-locked, oscillating arrays of up to 2,450 Josephson junctions. Because of the excellent yield and uniformity of the nanobridge junctions, they successfully applied the junction technology to a wide variety of circuits. These circuits included transmission-line pulse formers and 32 and 64-bit shift registers. The 32-bit shift register was shown to operate at clock speeds near 100 GHz and is believed to be one of the faster and more complex digital circuit demonstrated to date using high temperature superconductor technology.

  7. Octagonal Defects at Carbon Nanotube Junctions

    Directory of Open Access Journals (Sweden)

    W. Jaskólski

    2013-01-01

    Full Text Available We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (EF. The reconstructed junction has only one state near EF, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system.

  8. Fabrication of high quality ferromagnetic Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M. [Institute for Solid State Research, Research Centre Juelich, D-52425 Juelich (Germany) and CNI-Center of Nanoelectronic Systems for Information Technology, Research Centre Juelich, D-52425 Juelich (Germany)]. E-mail: m.weides@fz-juelich.de; Tillmann, K. [Institute for Solid State Research, Research Centre Juelich, D-52425 Juelich (Germany); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich, D-52425 Juelich (Germany); Kohlstedt, H. [Institute for Solid State Research, Research Centre Juelich, D-52425 Juelich (Germany); CNI-Center of Nanoelectronic Systems for Information Technology, Research Centre Juelich, D-52425 Juelich (Germany); Department of Material Science and Engineering and Department of Physics, University of Berkeley, CA 94720 (United States)

    2006-05-15

    We present ferromagnetic Nb/Al{sub 2}O{sub 3}/Ni{sub 60}Cu{sub 40}/Nb Josephson junctions (SIFS) with an ultrathin Al{sub 2}O{sub 3} tunnel barrier. The junction fabrication was optimized regarding junction insulation and homogeneity of current transport. Using ion-beam-etching and anodic oxidation we defined and insulated the junction mesas. The additional 2 nm thin Cu-layer below the ferromagnetic NiCu (SINFS) lowered interface roughness and ensured very homogeneous current transport. A high yield of junctional devices with j {sub c} spreads less than 2% was obtained.

  9. CFTR chloride channel in the apical compartments: spatiotemporal coupling to its interacting partners.

    Science.gov (United States)

    Li, Chunying; Naren, Anjaparavanda P

    2010-04-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-regulated chloride channel located primarily at the apical or luminal surfaces of epithelial cells in the airway, intestine, pancreas, kidney, sweat gland, as well as male reproductive tract, where it plays a crucial role in transepithelial fluid homeostasis. CFTR dysfunction can be detrimental and may result in life-threatening disorders. CFTR hypofunctioning because of genetic defects leads to cystic fibrosis, the most common lethal genetic disease in Caucasians, whereas CFTR hyperfunctioning resulting from various infections evokes secretory diarrhea, the leading cause of mortality in early childhood. Therefore, maintaining a dynamic balance between CFTR up-regulating processes and CFTR down-regulating processes is essential for maintaining fluid and body homeostasis. Accumulating evidence suggests that protein-protein interactions play a critical role in the fine-tuned regulation of CFTR function. A growing number of proteins have been reported to interact directly or indirectly with CFTR chloride channel, suggesting that CFTR might be coupled spatially and temporally to a wide variety of interacting partners including ion channels, receptors, transporters, scaffolding proteins, enzyme molecules, signaling molecules, and effectors. Most interactions occur primarily between the opposing terminal tails (amino or carboxyl) of CFTR protein and its binding partners, either directly or mediated through various PDZ scaffolding proteins. These dynamic interactions impact the channel function, as well as localization and processing of CFTR protein within cells. This article reviews the most recent progress and findings about the interactions between CFTR and its binding partners through PDZ scaffolding proteins, as well as the spatiotemporal regulation of CFTR-containing macromolecular signaling complexes in the apical compartments of polarized cells lining the secretory epithelia.

  10. Myocardial scarring on cardiovascular magnetic resonance in asymptomatic or minimally symptomatic patients with “pure” apical hypertrophic cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Kim Kyung-Hee

    2012-07-01

    Full Text Available Abstract Background Late gadolinium enhancement (LGE cardiovascular magnetic resonance (CMR enables state-of-the-art in vivo evaluations of myocardial fibrosis. Although LGE patterns have been well described in asymmetrical septal hypertrophy, conflicting results have been reported regarding the characteristics of LGE in apical hypertrophic cardiomyopathy (ApHCM. This study was undertaken to determine 1 the frequency and distribution of LGE and 2 its prognostic implication in ApHCM. Methods Forty patients with asymptomatic or minimally symptomatic pure ApHCM (age, 60.2 ± 10.4 years, 31 men were prospectively enrolled. LGE images were acquired using the inversion recovery segmented spoiled-gradient echo and phase-sensitive inversion recovery sequence, and analyzed using a 17-segment model. Summing the planimetered LGE areas in all short axis slices yielded the total volume of late enhancement, which was subsequently presented as a proportion of total LV myocardium (% LGE. Results Mean maximal apical wall thickness was 17.9±2.3mm, and mean left ventricular (LV ejection fraction was 67.7 ± 8.0%. All but one patient presented with electrocardiographic negative T wave inversion in anterolateral leads, with a mean maximum negative T wave of 7.2 ± 4.7mm. Nine patients (22.5% had giant negative T waves, defined as the amplitude of ≥10mm, in electrocardiogram. LGE was detected in 130 segments of 30 patients (75.0%, occupying 4.9 ± 5.5% of LV myocardium. LGE was mainly detected at the junction between left and right ventricles in 12 (30% and at the apex in 28 (70%, although LGE-positive areas were widely distributed, and not limited to the apex. Focal LGE at the non-hypertrophic LV segments was found in some ApHCM patients, even without LGE of hypertrophied apical segments. Over the 2-year follow-up, there was no one achieving the study end-point, defined as all-cause death, sudden cardiac death and hospitalization for heart failure

  11. Myocardial edema in Takotsubo syndrome mimicking apical hypertrophic cardiomyopathy: An insight into diagnosis by cardiovascular magnetic resonance.

    Science.gov (United States)

    Izgi, Cemil; Ray, Sanjoy; Nyktari, Evangelia; Alpendurada, Francisco; Lyon, Alexander R; Rathore, Sudhir; Baksi, Arun John

    2015-01-01

    Myocardial edema is one of the characteristic features in the pathogenesis of Takotsubo syndrome. We report a middle aged man who presented with typical clinical and echocardiographic features of apical variant of Takotsubo syndrome. However, a cardiovascular magnetic resonance study performed 10 days after presentation did not show any apical 'ballooning' but revealed features of an apical hypertrophic cardiomyopathy on cine images. Tissue characterization with T2 weighted images proved severe edema as the cause of significantly increased apical wall thickness. A follow-up cardiovascular magnetic resonance study was performed 5 months later which showed that edema, wall thickening and the appearance of apical hypertrophic cardiomyopathy all resolved, confirming Takotsubo syndrome as the cause of the initial appearance. As the affected myocardium most commonly involves the apical segments, an edema induced increase in apical wall thickness may lead to appearances of an apical hypertrophic cardiomyopathy rather than apical ballooning in the acute to subacute phase of Takotsubo syndrome.

  12. Computational and biophysical approaches to protein-protein interaction inhibition of Plasmodium falciparum AMA1/RON2 complex

    Science.gov (United States)

    Pihan, Emilie; Delgadillo, Roberto F.; Tonkin, Michelle L.; Pugnière, Martine; Lebrun, Maryse; Boulanger, Martin J.; Douguet, Dominique

    2015-06-01

    Invasion of the red blood cell by Plasmodium falciparum parasites requires formation of an electron dense circumferential ring called the Moving Junction (MJ). The MJ is anchored by a high affinity complex of two parasite proteins: Apical Membrane Antigen 1 ( PfAMA1) displayed on the surface of the parasite and Rhoptry Neck Protein 2 that is discharged from the parasite and imbedded in the membrane of the host cell. Structural studies of PfAMA1 revealed a conserved hydrophobic groove localized to the apical surface that coordinates RON2 and invasion inhibitory peptides. In the present work, we employed computational and biophysical methods to identify competitive P. falciparum AMA1-RON2 inhibitors with the goal of exploring the `druggability' of this attractive antimalarial target. A virtual screen followed by molecular docking with the PfAMA1 crystal structure was performed using an eight million compound collection that included commercial molecules, the ChEMBL malaria library and approved drugs. The consensus approach resulted in the selection of inhibitor candidates. We also developed a fluorescence anisotropy assay using a modified inhibitory peptide to experimentally validate the ability of the selected compounds to inhibit the AMA1-RON2 interaction. Among those, we identified one compound that displayed significant inhibition. This study offers interesting clues to improve the throughput and reliability of screening for new drug leads.

  13. THE CELULAR JUNCTIONS AND THE EMERGENCE OF ANIMALS

    Directory of Open Access Journals (Sweden)

    Urquiza-Bardone, Sergio

    2013-07-01

    Full Text Available The emergence of multicellularity and epithelia in relation to the appearance of cellular junctions, in order to illustrate the first steps of animal evolution, is discussed. We analyzed the structure and roles of adherens and occludins, considered to be the oldest. Also treated are some aspects of the main proteins that constitute them, the cadherins and claudins, as well as the related structures observed in sponges and choanoflagellates, the most ancient animals and the ancestors of these, respectively. It was concluded that the animal ancestor probably possessed some kind of adherens and possibly occludins, appearing as the first of major importance. These junctions increased in complexity through until the complexity observed in modern times.

  14. Seebeck effect in molecular junctions

    Science.gov (United States)

    Zimbovskaya, Natalya A.

    2016-05-01

    Advances in the fabrication and characterization of nanoscale systems presently allow for a better understanding of their thermoelectric properties. As is known, the building blocks of thermoelectricity are the Peltier and Seebeck effects. In the present work we review results of theoretical studies of the Seebeck effect in single-molecule junctions and similar systems. The behavior of thermovoltage and thermopower in these systems is controlled by several factors including the geometry of molecular bridges, the characteristics of contacts between the bridge and the electrodes, the strength of the Coulomb interactions between electrons on the bridge, and of electron-phonon interactions. We describe the impact of these factors on the thermopower. Also, we discuss a nonlinear Seebeck effect in molecular junctions.

  15. Electron transport in molecular junctions

    DEFF Research Database (Denmark)

    Jin, Chengjun

    This thesis addresses the electron transport in molecular junctions, focusing on the energy level alignment and correlation effects. Various levels of theory have been applied to study the structural and electronic effects in different molecular junctions, starting from the single particle density...... charge position are in quantitative agreement with the experiments, while pure DFT is not. This is the consequence of the accurate energy level alignment, where the DFT+∑ method corrects the self-interaction error in the standard DFT functional and uses a static image charge model to include the image...... charge effect on the energy level renormalization. Additionally, the gating of the 4,4’-bipyridine (44BP) molecule contacted to either Ni or Au electrodes has been investigated. Here it is found that the gating mechanism is conceptually different between two cases. In the case of Ni contacts where...

  16. How coherent are Josephson junctions?

    CERN Document Server

    Paik, Hanhee; Bishop, Lev S; Kirchmair, G; Catelani, G; Sears, A P; Johnson, B R; Reagor, M J; Frunzio, L; Glazman, L; Schoelkopf, R J

    2011-01-01

    Attaining sufficient coherence is a requirement for realizing a large-scale quantum computer. We present a new implementation of a superconducting transmon qubit that is strongly coupled to a three-dimensional superconducting cavity. We observe a reproducible increase in the coherence times of qubit (both $T_1$ and $T_2$ > 10 microseconds) and cavity ($T_{cav}$ ~ 50 microseconds) by more than an order of magnitude compared to the current state-of-art superconducting qubits. This enables the study of the stability and quality of Josephson junctions at precisions exceeding one part per million. Surprisingly, we see no evidence for $1/f$ critical current noise. At elevated temperatures, we observe the dissipation due to a small density (< 1 - 10 ppm) of thermally-excited quasiparticles. The results suggest that the overall quality of Josephson junctions will allow error rates of a few $10^{-4}$, approaching the error correction threshold.

  17. Radial left ventricular dyssynchrony by speckle tracking in apical versus non apical right ventricular pacing- evidence of dyssynchrony on medium term follow up

    Directory of Open Access Journals (Sweden)

    Dinesh Choudhary

    2016-03-01

    Conclusion: Pacing in non apical location (RV mid septum or low RVOT is associated with less dyssynchrony by specific measures like 2D radial strain and correlates with better ventricular function in long term.

  18. Shoot apical meristem maintenance: the art of a dynamic balance.

    Science.gov (United States)

    Carles, Cristel C; Fletcher, Jennifer C

    2003-08-01

    The aerial structure of higher plants derives from cells at the tip of the stem, in the shoot apical meristem (SAM). Throughout the life of a plant, the SAM produces stem tissues and lateral organs, and also regenerates itself. For correct growth, the plant must maintain a constant flow of cells through the meristem, where the input of dividing pluripotent stem cells offsets the output of differentiating cells. This flow depends on extracellular signaling within the SAM, governed by a spatial regulatory feedback loop that maintains a reservoir of stem cells, and on factors that prevent meristem cells from differentiating prematurely. The terminating floral meristem incorporates the spatial regulation scheme into a temporal regulation pathway involving flower patterning factors.

  19. Cryopreservation of Galanthus elwesii Hook. apical meristems by droplet vitrification.

    Science.gov (United States)

    Maslanka, M; Panis, B; Bach, A

    2013-01-01

    The aim of this study was to develop an efficient cryopreservation protocol for the geophyte giant snowdrop (Galanthus elwesii Hook.) that guarantees a high rate of survival and plant regeneration after cryopreservation. The excised apical meristems were obtained from cultures of in vitro grown bulb scales. Using a vitrification procedure and optimizing the duration of the exposure to the loading solution (LS), meristem post-rewarm survival rates higher than 90 percent were achieved. Also regrowth percentages were very high, ranging from 87 to 91 percent. After optimizing the time of exposure to the plant vitrification solution (PVS2), the survival rate was between 83 and 97 percent. During post-rewarm regeneration, good growth recovery was as high as 76 percent; however, hyperhydration and callusing were also observed. The results demonstrate that cryopreservation of Galanthus elwesii germplasm seems to be feasible.

  20. Geometry of shoot apical dome and distribution of growth rates

    Directory of Open Access Journals (Sweden)

    Jerzy Nakielski

    2014-01-01

    Full Text Available The distribution of the relative elementary rate of growth (RERG in apical domes of various shapes and patterns of displacement lines can be analytically examined. The geometry of these domes may be described by parabolas of n-th order, the variant of the distribution of linear growth rate should be established along any displacement line (e.g. along the axis and then the RERG can be studied as the function depending on the position coordinates and the parameter n. Such investigations of several aplical domes of various shapes have been performed. The results confirm the occurrence of the minimum of relative, elementary growth rate (in volume in the subapical region of the dome independently of the type of geometry (n parabola order.

  1. Risk variables of external apical root resorption during orthodontic treatment

    Directory of Open Access Journals (Sweden)

    Maria Carolina Feio Barroso

    2012-04-01

    Full Text Available INTRODUCTION: External apical root resorption (EARR is an adverse outcome of the orthodontic treatment. So far, no single or associated factor has been identified as responsible for EARR due to tooth movement. OBJECTIVE: This study investigated the association of risk variables (age, gender, extraction for orthodontic treatment and Angle classification with EARR and orthodontic treatment. METHOD: The sample (n=72 was divided into two groups according to presence (n=32 or absence (n=40 of EARR in maxillary central and lateral incisors after orthodontic treatment. RESULTS: There were no statistically significant differences in EARR according to age, gender, extraction or type of malocclusion (p>0.05. CONCLUSION: The risk variables examined were not associated with EARR in the study population.

  2. Growth and development of the root apical meristem.

    Science.gov (United States)

    Perilli, Serena; Di Mambro, Riccardo; Sabatini, Sabrina

    2012-02-01

    A key question in plant developmental biology is how cell division and cell differentiation are balanced to modulate organ growth and shape organ size. In recent years, several advances have been made in understanding how this balance is achieved during root development. In the Arabidopsis root meristem, stem cells in the apical region of the meristem self-renew and produce daughter cells that differentiate in the distal meristem transition zone. Several factors have been implicated in controlling the different functional zones of the root meristem to modulate root growth; among these, plant hormones have been shown to play a main role. In this review, we summarize recent findings regarding the role of hormone signaling and transcriptional networks in regulating root development.

  3. Serious arrhythmias in patients with apical hypertrophic cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Okishige, Kaoru; Sasano, Tetsuo; Yano, Kei; Azegami, Kouji; Suzuki, Kou; Itoh, Kuniyasu [Yokohama Red Cross Hospital (Japan)

    2001-05-01

    We report cases of serious arrhythmias associated with apical hypertrophic cardiomyopathy (AHCM). Thirty-one patients were referred to our institute to undergo further assessment of their AHCM from 1988 to 1999. Three patients with nonsustained ventricular tachycardia demonstrated an {sup 123}I-MIBG regional reduction in the tracer uptake. In two patients with ventricular fibrillation (VF), the findings from {sup 123}I-MIBG imaging revealed regional sympathetic denervation in the inferior and lateral regions. Electrophysiologic study demonstrated reproducible induction of VF in aborted sudden death and presyncopal patients, resulting in the need for an implantable defibrillator device and amiodarone in each patient. Patients with refractory atrial fibrillation with a rapid ventricular response suffered from serious congestive heart failure. A prudent assessment and strategy in patients with this disease would be indispensable in avoiding a disastrous outcome. (author)

  4. Domain Wall Junction in N=2 Supersymmetric QED in four dimensions

    CERN Document Server

    Kakimoto, K; Kakimoto, Kazuya; Sakai, Norisuke

    2003-01-01

    An exact solution of domain wall junction is obtained in N=2 supersymmetric (SUSY) QED with three massive hypermultiplets. The junction preserves two out of eight SUSY. Both a (magnetic) Fayet-Iliopoulos (FI) term and complex masses for hypermultiplets are needed to obtain the junction solution. There are zero modes corresponding to spontaneously broken translation, SUSY, and U(1). All broken and unbroken SUSY charges are explicitly worked out in the Wess-Zumino gauge in N=1 superfields as well as in components. The relation to models in five dimensions is also clarified.

  5. Evaluation of the formation of a junctional DNA nanostructure through annealing curve analysis.

    Science.gov (United States)

    Shin, Seung Won; Park, Kyung Soo; Um, Soong Ho

    2015-02-20

    During the self-assembly of different numbers of oligonucleotides comprising junctional DNA nanostructures, a change in environmental variables (e.g., temperature or salt concentration) has a substantial influence on the final products. Further, distinctive annealing temperatures of oligonucleotides are observed depending on the state of hybridization. Here, we present an evaluation of the annealing characteristics of oligonucleotides for the formation of a simple junctional DNA nanostructure using an annealing curve analysis. This method may be useful for analyzing the formation of complex junctional DNA nanostructures.

  6. Cigarette smoke disrupts the integrity of airway adherens junctions through the aberrant interaction of p120-catenin with the cytoplasmic tail of MUC1

    Science.gov (United States)

    Zhang, Lili; Gallup, Marianne; Zlock, Lorna; Basbaum, Carol; Finkbeiner, Walter E.; McNamara, Nancy A.

    2014-01-01

    Adherens junctions (AJs) containing epithelial cadherin (E-cad) bound to p120-catenin (p120ctn) and β-catenin (β-ctn) play a crucial role in regulating cell–cell adhesion. Cigarette smoke abrogates cell–cell adhesion between epithelial cells by disrupting E-cad, a hallmark of epithelial–mesenchymal transition (EMT), yet the underlying mechanism remains unknown. We used an organotypic culture of primary human bronchial epithelial (HBE) cells treated with smoke-concentrated medium (Smk) to establish an essential role for the interaction between p120ctn and the cytoplasmic tail of MUC1 (MUC1-CT) in regulating E-cad disruption. Within the first 4 h of smoke exposure, apical MUC1-CT repositioned to the basolateral membrane of pseudo-stratified HBE cells, where it interacted with p120ctn. A time-dependent increase in MUC1-CT/p120ctn complexes occurred in conjunction with a time-dependent dissociation of p120ctn/E-cad/β-ctn complexes, as well as the coordinated degradation of p120ctn and E-cad. Interestingly, Smk induced a similar interaction between MUC1-CT and β-ctn, but this occurred 44 h after MUC1-CT’s initial interaction with p120ctn, and well after the AJs were destroyed. Blocking MUC1-CT’s interaction with p120ctn using a MUC1-CT dominant-negative peptide, PMIP, successfully abolished Smk’s disruptive effects on AJs and recovered apical-basolateral polarity of HBE cells. The MUC1-CT/p120ctn interaction was highly dependent on EGFR/Src/Jnk-mediated tyrosine phosphorylation (TyrP) of MUC1-CT. Accordingly, EGFR, Src or Jnk inhibitors (AG1478, PP2, SP600125, respectively) abrogated Smk-induced MUC1-CT-TyrP, MUC1-CT/p120ctn interaction, AJ disruption, and loss of cellular polarity. Our work identified MUC1-CT and p120ctn as important regulators of epithelial polarity and cell-cell adhesion during a smoke-induced EMT-like process. Novel therapeutics designed to inhibit MUC1-CT/p120ctn complex formation may prevent EMT in the smoker’s airway. PMID

  7. Oral microbiota species in acute apical endodontic abscesses

    Directory of Open Access Journals (Sweden)

    Noelle George

    2016-03-01

    Full Text Available Background and objectives: Acute apical abscesses are serious endodontic diseases resulting from pulpal infection with opportunistic oral microorganisms. The objective of this study was to identify and compare the oral microbiota in patients (N=18 exhibiting acute apical abscesses, originating from the demographic region in Portland, Oregon. The study hypothesis is that abscesses obtained from this demographic region may contain unique microorganisms not identified in specimens from other regions. Design: Endodontic abscesses were sampled from patients at the Oregon Health & Science University (OHSU School of Dentistry. DNA from abscess specimens was subjected to polymerase chain reaction amplification using 16S rRNA gene-specific primers and Cy3-dCTP labeling. Labeled DNA was then applied to microbial microarrays (280 species generated by the Human Oral Microbial Identification Microarray Laboratory (Forsyth Institute, Cambridge, MA. Results: The most prevalent microorganisms, found across multiple abscess specimens, include Fusobacterium nucleatum, Parvimonas micra, Megasphaera species clone CS025, Prevotella multisaccharivorax, Atopobium rimae, and Porphyromonas endodontalis. The most abundant microorganisms, found in highest numbers within individual abscesses, include F. nucleatum, P. micra, Streptococcus Cluster III, Solobacterium moorei, Streptococcus constellatus, and Porphyromonas endodontalis. Strong bacterial associations were identified between Prevotella multisaccharivorax, Acidaminococcaceae species clone DM071, Megasphaera species clone CS025, Actinomyces species clone EP053, and Streptococcus cristatus (all with Spearman coefficients >0.9. Conclusions: Cultivable and uncultivable bacterial species have been identified in endodontic abscesses obtained from the Portland, Oregon demographic region, and taxa identifications correlated well with other published studies, with the exception of Treponema and Streptococcus cristae, which

  8. Thermoelectric efficiency of molecular junctions

    Science.gov (United States)

    Perroni, C. A.; Ninno, D.; Cataudella, V.

    2016-09-01

    Focus of the review is on experimental set-ups and theoretical proposals aimed to enhance thermoelectric performances of molecular junctions. In addition to charge conductance, the thermoelectric parameter commonly measured in these systems is the thermopower, which is typically rather low. We review recent experimental outcomes relative to several junction configurations used to optimize the thermopower. On the other hand, theoretical calculations provide estimations of all the thermoelectric parameters in the linear and non-linear regime, in particular of the thermoelectric figure of merit and efficiency, completing our knowledge of molecular thermoelectricity. For this reason, the review will mainly focus on theoretical studies analyzing the role of not only electronic, but also of the vibrational degrees of freedom. Theoretical results about thermoelectric phenomena in the coherent regime are reviewed focusing on interference effects which play a significant role in enhancing the figure of merit. Moreover, we review theoretical studies including the effects of molecular many-body interactions, such as electron-vibration couplings, which typically tend to reduce the efficiency. Since a fine tuning of many parameters and coupling strengths is required to optimize the thermoelectric conversion in molecular junctions, new theoretically proposed set-ups are discussed in the conclusions.

  9. Supersymmetry Enhancement and Junctions in S-folds

    CERN Document Server

    Imamura, Yosuke; Yokoyama, Daisuke

    2016-01-01

    We study supersymmetry enhancement from ${\\cal N}=3$ to ${\\cal N}=4$ proposed by Aharony and Tachikawa by using string junctions in S-folds. The central charges carried by junctions play a central role in our analysis. We consider planer junctions in a specific plane. Before the S-folding they carry two complex central charges, which we denote by $Z$ and $\\bar Z$. The S-fold projection eliminates $\\bar Z$ as well as one of the four supercharges, and when the supersymmetry is enhanced $\\bar Z$ should be reproduced by some non-perturbative mechanism. For the models of $\\mathbb{Z}_3$ and $\\mathbb{Z}_4$ S-folds which are expected to give $SU(3)$ and $SO(5)$ ${\\cal N}=4$ theories we compare the junction spectra with those in perturbative brane realization of the same theories. We establish one-to-one correspondence so that $Z$ coincides. By using the correspondence we also give an expression for the enhanced central charge $\\bar Z$.

  10. Immunolocalization of FGF8/10 in the Apical Epidermal Peg and Blastema of the regenerating tail in lizard marks this apical growing area.

    Science.gov (United States)

    Alibardi, Lorenzo

    2016-07-01

    Previous studies have shown that Fibroblast Growth Factors are present in the regenerating tail tissues of lizards where they may stimulate the process of regeneration. The present study is focused on the immunolocalization of FGF8 and FGF10 in the regenerating lizard tail, two signaling proteins of the apical epidermal cup/ridge and mesenchymal blastema sustaining tail and limb regeneration in amphibians and the development of the tail and limbs in vertebrate embryos. Main immunoreactive protein bands at 15-18kDa for FGF8/10 are detected in the regenerating epidermis and only a band at 30 or 35kDa in the underlying connective tissues. FGF8 appears particularly localized in cells and nuclei of the apical epidermal peg and of the ependymal ampulla present at the tip of the regenerating tail. FGF10 is also immuno-localized in the apical epidermis but is particularly intensely localized in the mesenchyme of the apical blastema. In accordance with previous studies, the present observations supports the hypothesis that the apical epidermal peg and the ependymal tube with the few regenerated neurons present within it, release FGF8/10 that may contribute to maintenance of cell proliferation in the apical front of the mesenchyme for the growth of the regenerating tail.

  11. Width of the $0-\\pi$ phase transition in diffusive magnetic Josephson junctions

    OpenAIRE

    Shomali, Zahra; Zareyan, Malek; Belzig, Wolfgang

    2008-01-01

    We investigate the Josephson current between two superconductors (S) which are connected through a diffusive magnetic junction with a complex structure (F$_{c}$). Using the quantum circuit theory, we obtain the phase diagram of 0 and $\\pi$ Josephson couplings for F$_{c}$ being a IFI (insulator-ferromagnet-insulator) double barrier junction or a IFNFI structure (where N indicates a normal metal layer). Compared to a simple SFS structure, we find that the width of the transition, defined by the...

  12. Aquaporin-2: COOH terminus is necessary but not sufficient for routing to the apical membrane.

    NARCIS (Netherlands)

    Deen, P.M.T.; Balkom, B.W.M. van; Savelkoul, P.J.M.; Kamsteeg, E.J.; Raak, M.M.J.P. van; Jennings, M.L.; Muth, T.R.; Rajendran, V.; Caplan, M.J.

    2002-01-01

    Renal regulation of mammalian water homeostasis is mediated by the aquaporin-1 (AQP1) water channel, which is expressed in the apical and basolateral membranes of proximal tubules and descending limbs of Henle, and aquaporin-2 (AQP2), which is redistributed from intracellular vesicles to the apical

  13. Determination of working length for teeth with wide or immature apices: a review.

    Science.gov (United States)

    Kim, Y J A; Chandler, N P

    2013-06-01

    Practitioners face several challenges during the root canal treatment of teeth with wide or immature apices, one of which is working length determination. There is relatively little data regarding the value of radiography and electronic apex locator (EAL) use when root formation is incomplete, and supplementary measurement techniques may be helpful. This review considers length determination for canals with wide or completely open apices in permanent and primary teeth. The Ovid Medline, Web of Science and Scopus databases were searched individually and in combinations to August 2012 using the subject headings 'working length determination' and 'open apex' and revealed only one article. Further headings, 'tooth apex', 'apical constriction', 'resorption', 'foramen size', 'mature root apex', 'immature root apex', 'working length determination', 'apexification', 'open apices', 'open apex', 'open apical foramina', 'canal length determination', 'immature teeth', 'apical diameters', 'electronic apex locators', 'primary teeth', 'treatment outcome' and 'clinical outcome' were entered. Potentially useful articles were chosen for a manual search of bibliography as well as a forward search of citations. Other investigations revealed case reports and some research related to open apices and laboratory studies evaluating EALs, radiography and tactile methods. Some involved permanent teeth of various apical diameters and primary teeth with and without resorption. There is a need to define the term 'open apex'. Clinicians should be aware of the benefits and limitations of all canal measuring techniques involved in managing this problem.

  14. Prognostic factors in apical surgery with root-end filling: a meta-analysis

    DEFF Research Database (Denmark)

    von Arx, Thomas; Peñarrocha, Miguel; Jensen, Storgård

    2010-01-01

    Apical surgery has seen continuous development with regard to equipment and surgical technique. However, there is still a shortage of evidence-based information regarding healing determinants. The objective of this meta-analysis was to review clinical articles on apical surgery with root-end fill...

  15. Haemostatic effect and tissue reactions of methods and agents used for haemorrhage control in apical surgery

    DEFF Research Database (Denmark)

    Jensen, Simon Storgaard; Yazdi, P M; Hjørting-Hansen, Erik

    2010-01-01

    To compare the haemostatic effect and tissue reactions of different agents and methods used for haemorrhage control in apical surgery.......To compare the haemostatic effect and tissue reactions of different agents and methods used for haemorrhage control in apical surgery....

  16. Chaos induced by coupling between Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu. M.; Azemtsa-Donfack, H.; Botha, A. E.

    2015-02-01

    It is found that, in a stack of intrinsic Josephson junctions in layered high temperature superconductors under external electromagnetic radiation, the chaotic features are triggered by interjunction coupling, i.e., the coupling between different junctions in the stack. While the radiation is well known to produce chaotic effects in the single junction, the effect of interjunction coupling is fundamentally different and it can lead to the onset of chaos via a different route to that of the single junction. A precise numerical study of the phase dynamics of intrinsic Josephson junctions, as described by the CCJJ+DC model, is performed. We demonstrate the charging of superconducting layers, in a bias current interval corresponding to a Shapiro step subharmonic, due to the creation of a longitudinal plasma wave along the stack of junctions. With increase in radiation amplitude chaotic behavior sets in. The chaotic features of the coupled Josephson junctions are analyzed by calculations of the Lyapunov exponents. We compare results for a stack of junctions to the case of a single junction and prove that the observed chaos is induced by the coupling between the junctions. The use of Shapiro step subharmonics may allow longitudinal plasma waves to be excited at low radiation power.

  17. [Remodeling of cardiac gap junctions and arrhythmias].

    Science.gov (United States)

    Yu, Zhi-Bin; Sheng, Juan-Juan

    2011-12-25

    In the heart, gap junctions mediate electrical and chemical coupling between adjacent cardiomyocytes, forming the cell-to-cell pathways for orderly spread of the wave of electrical excitation responsible for a functional syncytium. Three principal connexins are expressed in cardiomyocytes, connexin 43 (CX43), CX40, and CX45. CX43 predominates in ventricular muscle cells. Most of the gap junctions, assembled from CX43, are located at the intercalated discs, often with larger junctional plaques at the disc periphery. The gap junctions are rarely distributed to the sides of the cardiomyocyte. The ischemia-reperfusion, cardiac hypertrophy, heart failure, hypercholesterolemia, and diabetes mellitus induce gap junction remodeling. The gap junction remodeling induced by above-mentioned diseases shows similar characteristics, including down-regulation of CX43, reduction in gap junction plaque size, increased heterogeneity and lateralization of gap junction distribution, and dephosphorylation of CX43. The elevated angiotensin II concentration in local myocardium may play an important role in the gap junction remodeling. The down-regulation of CX43 and lateralization of gap junction distribution alter anisotropic spread of the impulse of ventricular myocardium. The dephosphorylation of CX43 not only reduces electrical conductance, but also decreases permeability of chemicals between cardiomyocytes. The lateralization of gap junctions may increase the number of hemichannels formed by CX43. The opening of hemichannels induces ATP efflux and Na(+) influx, which forms a delayed after-depolarization. The gap junction remodeling in pathological condition produces arrhythmia substrate in the ventricles. In this review, the current knowledge on the relationship between the remodeling of cardiac gap junctions and arrhythmias were summarized.

  18. Glyphosate effects on the gene expression of the apical bud in soybean (Glycine max).

    Science.gov (United States)

    Jiang, Ling-Xue; Jin, Long-Guo; Guo, Yong; Tao, Bo; Qiu, Li-Juan

    2013-08-09

    Glyphosate is a broad spectrum, non-selective herbicide which has been widely used for weed control. Much work has focused on elucidating the high accumulation of glyphosate in shoot apical bud (shoot apex). However, to date little is known about the molecular mechanisms of the sensitivity of shoot apical bud to glyphosate. Global gene expression profiling of the soybean apical bud response to glyphosate treatment was performed in this study. The results revealed that the glyphosate inhibited tryptophan biosynthesis of the shikimic acid pathway in the soybean apical bud, which was the target site of glyphosate. Glyphosate inhibited the expression of most of the target herbicide site genes. The promoter sequence analysis of key target genes revealed that light responsive elements were important regulators in glyphosate induction. These results will facilitate further studies of cloning genes and molecular mechanisms of glyphosate on soybean shoot apical bud. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Endodontic management of open apex using Biodentine as a novel apical matrix.

    Science.gov (United States)

    Khetarpal, Ambica; Chaudhary, Sarika; Talwar, Sangeeta; Verma, Mahesh

    2014-01-01

    Endodontic management of open apex using Biodentine as an apical matrix. Summary : An immature tooth with pulpal necrosis and periapical pathology imposes a great difficulty to the endodontist. Endodontic treatment options for such teeth consist of conventional apexification procedure with and without apical barriers. Biodentine™ is new calcium silicate based cement that exhibits physical and chemical properties similar to those described for certain Portland cement derivatives. This article demonstrates the use of the newer material, Biodentine as an apical matrix barrier in root end apexification procedure. This case reports present apexification and successful healing with the use of Biodentine as an apical barrier matrix. Conclusion : Apexification in one step using an apical plug of Biodentine can be considered a predictable treatment and may be an alternative to mineral trioxide aggregate apexification.

  20. Effect of master apical file size and taper on irrigation and cleaning of the apical third of curved canals.

    Directory of Open Access Journals (Sweden)

    Nahid Mohammadzadeh Akhlaghi

    2014-04-01

    Full Text Available Canal preparation generates a substantial amount of debris and smear layer (SL. The size and taper of the Master Apical File (MAF affects on penetration of irrigants and subsequently canal cleaning efficacy. The aim of this study was to evaluate the effect of MAF size and taper on penetration of irrigants to the apical third of curved mesiobuccal (MB canals of mandibular first molars.Eighty-nine human mandibular first molars were divided into one control group (n=5 without rotary instrumentation and 6 experimental groups (n=14 each that were prepared with the following RaCe rotary files as MAF: 25.04 (group1, 25.06 (group 2, 30.04 (group 3, 30.06 (group 4, 35.04 (group 5 and 35.06 (group 6. All the experimental groups were rinsed with 2 ml of 17 % EDTA followed by 2 ml of 5.25% NaOCl. Debridement of the MB canals was evaluated using scanning electron microscope (SEM. The data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests (P<0.05.Group 6 (MAF=35.06 showed 100% acceptable debridement. This rate was 92.9% for MAF=35.04. In group 4 (MAF=30.06 smear layer (SL was removed in the three-forth of the samples and debris was removed in 92.9% of them. Acceptable debridement was not achieved in most samples of groups 1 and 2 (25.04 and 25.06, respectively and the mentioned two groups had statistically significant difference in this respect with the other groups (P<0.05.Based on this study, 30.06 may be considered as the minimum MAF size for acceptable debridement.

  1. Arecoline induced disruption of expression and localization of the tight junctional protein ZO-1 is dependent on the HER 2 expression in human endometrial Ishikawa cells.

    Science.gov (United States)

    Giri, Sarbani; Poindexter, Kevin M; Sundar, Shyam N; Firestone, Gary L

    2010-07-06

    Approximately 600 million people chew Betel nut, making this practice the fourth most popular oral habit in the world. Arecoline, the major alkaloid present in betel nut is one of the causative agents for precancerous lesions and several cancers of mouth among those who chew betel nut. Arecoline can be detected in the human embryonic tissue and is correlated to low birth weight of newborns whose mothers chew betel nut during pregnancy, suggesting that arecoline can induce many systemic effects. However, few reports exist as to the effects of arecoline in human tissues other than oral cancer cell lines. Furthermore, in any system, virtually nothing is known about the cellular effects of arecoline treatment on membrane associated signaling components of human cancer cells. Using the human Ishikawa endometrial cancer cell line, we investigated the effects of arecoline on expression, localization and functional connections between the ZO-1 tight junction protein and the HER2 EGF receptor family member. Treatment of Ishikawa cells with arecoline coordinately down-regulated expression of both ZO-1 and HER2 protein and transcripts in a dose dependent manner. Biochemical fractionation of cells as well as indirect immunofluorescence revealed that arecoline disrupted the localization of ZO-1 to the junctional complex at the cell periphery. Compared to control transfected cells, ectopic expression of exogenous HER2 prevented the arecoline mediated down-regulation of ZO-1 expression and restored the localization of ZO-1 to the cell periphery. Furthermore, treatment with dexamethasone, a synthetic glucocorticoid reported to up-regulate expression of HER2 in Ishikawa cells, precluded arecoline from down-regulating ZO-1 expression and disrupting ZO-1 localization. Arecoline is known to induce precancerous lesions and cancer in the oral cavity of betel nut users. The arecoline down-regulation of ZO-1 expression and subcellular distribution suggests that arecoline potentially

  2. Arecoline induced disruption of expression and localization of the tight junctional protein ZO-1 is dependent on the HER 2 expression in human endometrial Ishikawa cells

    Directory of Open Access Journals (Sweden)

    Sundar Shyam N

    2010-07-01

    Full Text Available Abstract Background Approximately 600 million people chew Betel nut, making this practice the fourth most popular oral habit in the world. Arecoline, the major alkaloid present in betel nut is one of the causative agents for precancerous lesions and several cancers of mouth among those who chew betel nut. Arecoline can be detected in the human embryonic tissue and is correlated to low birth weight of newborns whose mothers chew betel nut during pregnancy, suggesting that arecoline can induce many systemic effects. However, few reports exist as to the effects of arecoline in human tissues other than oral cancer cell lines. Furthermore, in any system, virtually nothing is known about the cellular effects of arecoline treatment on membrane associated signaling components of human cancer cells. Results Using the human Ishikawa endometrial cancer cell line, we investigated the effects of arecoline on expression, localization and functional connections between the ZO-1 tight junction protein and the HER2 EGF receptor family member. Treatment of Ishikawa cells with arecoline coordinately down-regulated expression of both ZO-1 and HER2 protein and transcripts in a dose dependent manner. Biochemical fractionation of cells as well as indirect immunofluorescence revealed that arecoline disrupted the localization of ZO-1 to the junctional complex at the cell periphery. Compared to control transfected cells, ectopic expression of exogenous HER2 prevented the arecoline mediated down-regulation of ZO-1 expression and restored the localization of ZO-1 to the cell periphery. Furthermore, treatment with dexamethasone, a synthetic glucocorticoid reported to up-regulate expression of HER2 in Ishikawa cells, precluded arecoline from down-regulating ZO-1 expression and disrupting ZO-1 localization. Conclusion Arecoline is known to induce precancerous lesions and cancer in the oral cavity of betel nut users. The arecoline down-regulation of ZO-1 expression and

  3. Apical Ca2+-activated potassium channels in mouse parotid acinar cells.

    Science.gov (United States)

    Almassy, Janos; Won, Jong Hak; Begenisich, Ted B; Yule, David I

    2012-02-01

    Ca(2+) activation of Cl and K channels is a key event underlying stimulated fluid secretion from parotid salivary glands. Cl channels are exclusively present on the apical plasma membrane (PM), whereas the localization of K channels has not been established. Mathematical models have suggested that localization of some K channels to the apical PM is optimum for fluid secretion. A combination of whole cell electrophysiology and temporally resolved digital imaging with local manipulation of intracellular [Ca(2+)] was used to investigate if Ca(2+)-activated K channels are present in the apical PM of parotid acinar cells. Initial experiments established Ca(2+)-buffering conditions that produced brief, localized increases in [Ca(2+)] after focal laser photolysis of caged Ca(2+). Conditions were used to isolate K(+) and Cl(-) conductances. Photolysis at the apical PM resulted in a robust increase in K(+) and Cl(-) currents. A localized reduction in [Ca(2+)] at the apical PM after photolysis of Diazo-2, a caged Ca(2+) chelator, resulted in a decrease in both K(+) and Cl(-) currents. The K(+) currents evoked by apical photolysis were partially blocked by both paxilline and TRAM-34, specific blockers of large-conductance "maxi-K" (BK) and intermediate K (IK), respectively, and almost abolished by incubation with both antagonists. Apical TRAM-34-sensitive K(+) currents were also observed in BK-null parotid acini. In contrast, when the [Ca(2+)] was increased at the basal or lateral PM, no increase in either K(+) or Cl(-) currents was evoked. These data provide strong evidence that K and Cl channels are similarly distributed in the apical PM. Furthermore, both IK and BK channels are present in this domain, and the density of these channels appears higher in the apical versus basolateral PM. Collectively, this study provides support for a model in which fluid secretion is optimized after expression of K channels specifically in the apical PM.

  4. Evaluation of apical subtype of hypertrophic cardiomyopathy using cardiac magnetic resonance imaging with gadolinium enhancement.

    Science.gov (United States)

    Kebed, Kalie Y; Al Adham, Raed I; Bishu, Kalkidan; Askew, J Wells; Klarich, Kyle W; Araoz, Philip A; Foley, Thomas A; Glockner, James F; Nishimura, Rick A; Anavekar, Nandan S

    2014-09-01

    Apical hypertrophic cardiomyopathy (HC) is an uncommon variant of HC. We sought to characterize cardiac magnetic resonance imaging (MRI) findings among apical HC patients. This was a retrospective review of consecutive patients with a diagnosis of apical HC who underwent cardiac MRI examinations at the Mayo Clinic (Rochester, MN) from August 1999 to October 2011. Clinical and demographic data at the time of cardiac MRI study were abstracted. Cardiac MRI study and 2-dimensional echocardiograms performed within 6 months of the cardiac MRI were reviewed; 96 patients with apical HC underwent cardiac MRI examinations. LV end-diastolic and end-systolic volumes were 130.7 ± 39.1 ml and 44.2 ± 20.9 ml, respectively. Maximum LV thickness was 19 ± 5 mm. Hypertrophy extended beyond the apex into other segments in 57 (59.4%) patients. Obstructive physiology was seen in 12 (12.5%) and was more common in the mixed apical phenotype than the pure apical (19.3 vs 2.6%, p = 0.02). Apical pouches were noted in 39 (40.6%) patients. Late gadolinium enhancement (LGE) was present in 70 (74.5%) patients. LGE was associated with severe symptoms and increased maximal LV wall thickness. In conclusion, cardiac MRI is well suited for studying the apical form of HC because of difficulty imaging the cardiac apex with standard echocardiography. Cardiac MRI is uniquely suited to delineate the presence or absence of an apical pouch and abnormal myocardial LGE that may have implications in the natural history of apical HM. In particular, the presence of abnormal LGE is associated with clinical symptoms and increased wall thickness.

  5. Effects of apical meristem mining on plant fitness, architecture, and flowering phenology in Cirsium altissimum (Asteraceae).

    Science.gov (United States)

    Adhikari, Subodh; Russell, F Leland

    2014-12-01

    • Interactions that limit lifetime seed production have the potential to limit plant population sizes and drive adaptation through natural selection. Effects of insect herbivory to apical meristems (apical meristem mining) on lifetime seed production rarely have been quantified experimentally. We studied Cirsium altissimum (tall thistle), whose meristems are mined by Platyptilia carduidactyla (artichoke plume moth), to determine how apical damage affects plant maternal fitness and evaluate both direct and indirect mechanisms underlying these effects.• In restored prairie, apical mining was manipulated on tall thistles by applying insecticide, water, or no spray to apical meristems. We quantified effects on lifetime seed production, plant architecture, and flowering phenology. Seed germinability and seedling mass were evaluated in a greenhouse.• Apical meristem miners decreased lifetime seed production of C. altissimum, but not seed quality. Higher mortality rates of damaged plants contributed to reduced seed production. Apical damage reduced plant height and increased the proportion of blooming flower heads in axial positions on branches. Apical damage delayed flowering and shortened flowering duration.• Apical meristem mining reduced plant maternal fitness. The shift in the identity of blooming flower heads from terminal to axial positions contributed to this reduction because axial heads are less fecund. Shorter, meristem-mined plants may have been more susceptible to competition, and this susceptibility may explain their higher mortality rates. The kinds of changes in architecture and phenology that resulted from apical damage to C. altissimum have been shown to affect floral visitation in other plant species. © 2014 Botanical Society of America, Inc.

  6. Computation of flow through the oesophagogastric junction

    Institute of Scientific and Technical Information of China (English)

    Barry P McMahon; Karl D Odie; Kenneth W Moloney; Hans Gregersen

    2007-01-01

    Whilst methods exist to indirectly measure the effects of increased flow or gastro-oesophageal refluxing,they cannot quantitatively measure the amount of acid travelling back up into the oesophagus during reflux, nor can they indicate the flow rate through the oesophagogastric junction (OGJ). Since OGJ dysfunction affects flow it seems most appropriate to describe the geometry of the OGJ and its effect on the flow.A device known as the functional lumen imaging probe (FLIP) has been shown to reliably measure the geometry of and pressure changes in the OGJ. FLIP cannot directly measure flow but the data gathered from the probe can be used to model flow through the junction by using computational flow dynamics (CFD).CFD uses a set of equations known as the Navier-Stokes equations to predict flow patterns and is a technique widely used in engineering. These equations are complex and require appropriate assumptions to provide simplifications before useful data can be obtained. With the assumption that the cross-sectional areas obtained via FLIP are circular, the radii of these circles can be obtained. A cubic interpolation scheme can then be applied to give a high-resolution geometry for the OGJ.In the case of modelling a reflux scenario, it can be seen that at the narrowest section a jet of fluid squirts into the oesophagus at a higher velocity than the fluid surrounding it. This jet has a maximum velocity of almost 2 ms-1 that occurs where the OGJ is at its narrowest. This simple prediction of acid 'squirting' into the oesophagus illustrates how the use of numerical methods can be used to develop a better understanding of the OGJ. This initial work using CFD shows some considerable promise for the future.

  7. Effect of Calcium Hydroxide Based Intracanal Medicaments on the Apical Sealing Ability of Resin Based Sealer and Guttapercha Obturated Root Canals

    Science.gov (United States)

    Sumanthini, MV; Shenoy, Vanitha U; Bodhwani, Mohit A

    2017-01-01

    Introduction Calcium Hydroxide (CH) is one of the most commonly used intracanal medicaments which can be used with various vehicles. Aim The aim of this in vitro study was to evaluate the effect of three CH based intracanal medicaments on the apical sealing ability of AH Plus – guttapercha obturation. Materials and Methods Crowns of 100 extracted single rooted human teeth were sectioned at the Cemento-Enamel Junction (CEJ) to a standardized length. The root canals were instrumented upto ISO size 40 using step back technique and the specimens were randomly divided into two control and four experimental groups. The control groups were not medicated. Specimens in positive control group (Group I) were obturated with guttapercha without placing sealer and in negative control group (Group II) were obturated with guttapercha and AH Plus sealer. Among the experimental groups, specimens of Group III were not medicated while groups IV, V and VI were medicated with CH-saline, CH-2% Chlorhexidine (CHX) and Vitapex respectively for a period of 14 days. The medicaments were removed from the specimens and the teeth were obturated with AH Plus sealer and guttapercha using lateral compaction technique. The specimens were immersed in India ink dye, demineralized and diphanized. The extent of dye penetration was assessed using a 10X stereomicroscope. Data obtained was statistically analyzed by one-way ANOVA (p<0.05) followed by Post-hoc Tukey test. Results Amongst the three CH medicaments, CH-2% CHX when used as an intracanal medicament showed a significantly higher microleakage as compared to the other groups with p<0.001. The microleakage values between the remaining groups were not statistically significant. Conclusion Under the conditions of this study it was concluded that all groups with or without intracanal medicament showed apical leakage. The vehicle used to carry CH may significantly influence the apical sealing ability of guttapercha – AH Plus obturated canals. PMID

  8. Physics and Applications of NIS Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Ullom, J N

    2001-08-24

    This paper reviews the physics and applications of Normal-Insulator-Superconductor (NIS) tunnel junctions. The current-voltage properties of NIS junctions are diode-like with a strong temperature dependence. Hence, these structures can be used as sensitive thermometers at temperatures well below the energy gap, {Delta}, of the superconducting electrode. For junction voltages comparable to {Delta}/q, current flow removes energy from the normal electrode. This property has been exploited to build refrigerators capable of cooling thin-film circuits from 0.3 K to 0.1 K. Calorimeters and bolometers for the detection of X-rays and millimeter-wave radiation, respectively, have successfully been built from NIS junctions. NIS junctions have also been used to probe the superconducting state. Finally, recent ideas for the use of NIS junctions as simple circuit elements are described.

  9. Algorithms for Junctions in Directed Acyclic Graphs

    CERN Document Server

    Ferreira, Carlos Eduardo

    2012-01-01

    Given a pair of distinct vertices u, v in a graph G, we say that s is a junction of u, v if there are in G internally vertex disjoint directed paths from s to u and from s to v. We show how to characterize junctions in directed acyclic graphs. We also consider the two problems in the following and derive efficient algorithms to solve them. Given a directed acyclic graph G and a vertex s in G, how can we find all pairs of vertices of G such that s is a junction of them? And given a directed acyclic graph G and k pairs of vertices of G, how can we preprocess G such that all junctions of k given pairs of vertices could be listed quickly? All junctions of k pairs problem arises in an application in Anthropology and we apply our algorithm to find such junctions on kinship networks of some brazilian indian ethnic groups.

  10. Basolateral junction proteins regulate competition for the follicle stem cell niche in the Drosophila ovary.

    Science.gov (United States)

    Kronen, Maria R; Schoenfelder, Kevin P; Klein, Allon M; Nystul, Todd G

    2014-01-01

    Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs) in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl) or discs large (dlg), undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib), do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones.

  11. Basolateral junction proteins regulate competition for the follicle stem cell niche in the Drosophila ovary.

    Directory of Open Access Journals (Sweden)

    Maria R Kronen

    Full Text Available Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl or discs large (dlg, undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib, do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones.

  12. The effect of an Nd-YAG pulsed laser on the cleaning of the root canal and the formation of a fused apical plug.

    Science.gov (United States)

    Saunders, W P; Whitters, C J; Strang, R; Moseley, H; Payne, A P; McGadey, J

    1995-07-01

    A Neodymium-yttrium aluminium garnet (Nd-YAG) pulsed laser was used in vitro to determine whether various laser energy levels from 0.75 W to 1.7 W at 15 pulses s(-1) (pps) were able to (i) remove debris from the walls of prepared root canals (ii) remove pulpal tissue from unprepared canals and (iii) create a fused apical plug from dentine chips, hydroxyapatite (HAP) or low-fusing dental porcelain. Single-rooted teeth were sectioned at the amelocemental junction and the crowns discarded. The root canals of 50 teeth were prepared chemomechanically and allocated to four groups of 10 teeth for laser treatment. One group was left unlased as a control. After lasing, the teeth were split longitudinally, stained and examined for residual debris. Results showed that there was no statistically significant difference between the groups (Plaser energy was applied to dentine chips, HAP and low-fusing porcelain in an attempt to produce a fused apical plug. The laser was unable to melt the dentine chips but some hardening of HAP occurred when combined with blue food-colouring, with or without glycerine, at energy levels of 1.0 W, at 15 pps for 30 s. Superficial hardening of low-fusing porcelain occurred at 1.0 W, 15 pps for 30 s.

  13. Contribution of cubilin and amnionless to processing and membrane targeting of cubilin-amnionless complex.

    Science.gov (United States)

    Coudroy, Gwénaëlle; Gburek, Jakub; Kozyraki, Renata; Madsen, Mette; Trugnan, Germain; Moestrup, Søren K; Verroust, Pierre J; Maurice, Michèle

    2005-08-01

    Cubilin is a peripheral apical membrane receptor for multiple ligands that are taken up in several absorptive epithelia. Recently, amnionless (AMN) was identified to form a functional receptor complex with cubilin. By expression in transfected polarized MDCK cells of AMN and several cubilin fragments, including a functional "mini" version of cubilin, the processing, sorting, and membrane anchoring of the complex to the apical membrane were investigated. The results show that truncation mutants, including the N-terminal domain of cubilin, did not appear at the plasma membrane but instead were retained in the endoplasmic reticulum or partially secreted into the medium. Coexpression with AMN led to efficient transport to the apical cell surface of the cubilin constructs, which included the EGF domains, and prevented release into the medium. AMN co-precipitated with cubilin and co-localized with cubilin at the apical cell surface. Apical sorting was observed for a broad set of nonoverlapping cubilin fragments without the N-terminal region, in the absence of AMN. The preference for apical sorting disappeared when glycosylation was inhibited by tunicamycin. In conclusion, it is shown that both units contribute to the processing of the cubilin-AMN complex to the apical membrane: AMN interacts with the EGF domains of cubilin and is responsible for membrane attachment and export of the complex from the endoplasmic reticulum, whereas the extracellular cubilin molecule is responsible for apical sorting of the complex in a carbohydrate-dependent manner.

  14. Molecular junctions: can pulling influence optical controllability?

    Science.gov (United States)

    Parker, Shane M; Smeu, Manuel; Franco, Ignacio; Ratner, Mark A; Seideman, Tamar

    2014-08-13

    We suggest the combination of single molecule pulling and optical control as a way to enhance control over the electron transport characteristics of a molecular junction. We demonstrate using a model junction consisting of biphenyl-dithiol coupled to gold contacts. The junction is pulled while optically manipulating the dihedral angle between the two rings. Quantum dynamics simulations show that molecular pulling enhances the degree of control over the dihedral angle and hence over the transport properties.

  15. Comparison of apical sealing and periapical extrusion of the ThermaFil obturation technique with and without MTA as an apical barrier: An in vitro study

    Directory of Open Access Journals (Sweden)

    Satish Kumar

    2011-01-01

    Full Text Available Aim: The aim of the study was to compare the conventional ThermaFil obturation technique and ThermaFil obturation with mineral trioxide aggregate (MTA as an apical barrier, with regard to apical sealing and extrusion. Materials and Methods: Twenty extracted human canines were instrumented using a crown-down technique and divided into two groups. The experimental group was obturated using ThermaFil obturation with MTA as an apical barrier and the control group was obturated using the conventional ThermaFil obturation technique. AH Plus sealer was used in both the groups. Apical extrusion was recorded. Teeth of both the groups were coated with nail polish, except for the apical 3 mm. After 24 h, they were suspended in black India ink for 48 h. Canines were decalcified, rendered transparent, and linear dye penetration was measured under ×40 stereomicroscope. Results: There was a significant extrusion noticed in conventional ThermaFil obturation technique. Frequency of extrusion of sealer and/or gutta-percha was supposed to be evaluated using χ² test, but since the values of the samples of ThermaFil plus MTA group were zero, statistical analysis could not be conducted, whereas linear dye leakage was calculated with Mann-Whitney U test because the distribution was abnormal. Conclusion: Although ThermaFil plus MTA group showed microleakage, extrusion of sealer and the core material was prevented in comparison with conventional ThermaFil obturation technique. It is advantageous to use MTA as an apical plug as there is no fear of apical extrusion and the root canal system can then be packed three dimensionally against this barrier using any thermoplasticized gutta-percha obturation technique.

  16. Pro-oxidant status and matrix metalloproteinases in apical lesions and gingival crevicular fluid as potential biomarkers for asymptomatic apical periodontitis and endodontic treatment response

    Directory of Open Access Journals (Sweden)

    Dezerega Andrea

    2012-03-01

    Full Text Available Abstract Background Oxidative stress and matrix metalloproteinases -9 and -2 are involved in periodontal breakdown, whereas gingival crevicular fluid has been reported to reflect apical status. The aim of this study was to characterize oxidant balance and activity levels of MMP -2 and -9 in apical lesions and healthy periodontal ligament; and second, to determine whether potential changes in oxidant balance were reflected in gingival crevicular fluid from asymptomatic apical periodontitis (AAP-affected teeth at baseline and after endodontic treatment. Methods Patients with clinical diagnosis of AAP and healthy volunteers having indication of tooth extraction were recruited. Apical lesions and healthy periodontal ligaments, respectively, were homogenized or processed to obtain histological tissue sections. Matrix metalloproteinase -9 and -2 levels and/or activity were analyzed by Immunowestern blot, zymography and consecutive densitometric analysis, and their tissue localization was confirmed by immunohistochemistry. A second group of patients with AAP and indication of endodontic treatment was recruited. Gingival crevicular fluid was extracted from AAP-affected teeth at baseline, after endodontic treatment and healthy contralateral teeth. Total oxidant and antioxidant status were determined in homogenized tissue and GCF samples. Statistical analysis was performed using STATA v10 software with unpaired t test, Mann-Whitney test and Spearman's correlation. Results Activity of MMP-2 and MMP-9 along with oxidant status were higher in apical lesions (p Conclusions Apical lesions display an oxidant imbalance along with increased activity of matrix metalloproteinase-2 and -9 and might contribute to AAP progression. Oxidant imbalance can also be reflected in GCF from AAP-affected teeth and was restored to normal levels after conservative endodontic treatment. These mediators might be useful as potential biomarkers for chair-side complementary diagnostic

  17. Loss models for long Josephson junctions

    DEFF Research Database (Denmark)

    Olsen, O. H.; Samuelsen, Mogens Rugholm

    1984-01-01

    A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement.......A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement....

  18. The serine protease-mediated increase in intestinal epithelial barrier function is dependent on occludin and requires an intact tight junction.

    Science.gov (United States)

    Ronaghan, Natalie J; Shang, Judie; Iablokov, Vadim; Zaheer, Raza; Colarusso, Pina; Dion, Sébastien; Désilets, Antoine; Leduc, Richard; Turner, Jerrold R; MacNaughton, Wallace K

    2016-09-01

    Barrier dysfunction is a characteristic of the inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Understanding how the tight junction is modified to maintain barrier function may provide avenues for treatment of IBD. We have previously shown that the apical addition of serine proteases to intestinal epithelial cell lines causes a rapid and sustained increase in transepithelial electrical resistance (TER), but the mechanisms are unknown. We hypothesized that serine proteases increase barrier function through trafficking and insertion of tight junction proteins into the membrane, and this could enhance recovery of a disrupted monolayer after calcium switch or cytokine treatment. In the canine epithelial cell line, SCBN, we showed that matriptase, an endogenous serine protease, could potently increase TER. Using detergent solubility-based cell fractionation, we found that neither trypsin nor matriptase treatment changed levels of tight junction proteins at the membrane. In a fast calcium switch assay, serine proteases did not enhance the rate of recovery of the junction. In addition, serine proteases could not reverse barrier disruption induced by IFNγ and TNFα. We knocked down occludin in our cells using siRNA and found this prevented the serine protease-induced increase in TER. Using fluorescence recovery after photobleaching (FRAP), we found serine proteases induce a greater mobile fraction of occludin in the membrane. These data suggest that a functional tight junction is needed for serine proteases to have an effect on TER, and that occludin is a crucial tight junction protein in this mechanism.

  19. Histologic Evaluation of Regenerative Endodontic Procedures with the Use of Chitosan Scaffolds in Immature Dog Teeth with Apical Periodontitis.

    Science.gov (United States)

    Palma, Paulo J; Ramos, João C; Martins, João B; Diogenes, Anibal; Figueiredo, Maria H; Ferreira, Paula; Viegas, Carlos; Santos, João M

    2017-08-01

    The aim of this study was to evaluate histologically the newly formed tissues after regenerative endodontic procedures (REPs) in dogs using either a blood clot (BC) or 2 different formulations of a chitosan hydrogel as scaffolds. Apical periodontitis was induced by inoculating immature teeth with oral plaque in 4 beagle dogs. Teeth (n = 96) were divided into 2 control (n = 20) and 4 test groups (n = 76) according to the treatment: apexification and REPs with BC, sodium hyaluronate:chitosan (HA:CS) scaffolds, or pectin:chitosan (P:CS) scaffolds. All root canals were disinfected with 2.5% sodium hypochlorite and a triple antibiotic paste intracanal medicament before evoked bleeding, clot formation, or scaffold placement. Thirteen weeks after treatment, the animals were sacrificed and the jaw blocks harvested for histologic processing, histomorphometric analysis, and statistical analysis. The lumens of the root canals were completely filled with mineral trioxide aggregate with evidence of a mineralized apical bridge between the root canal walls in 83% of the samples in the apexification group. Vital vascularized tissue was found in the REP groups; apical closure happened in 66.7% of these treatments, and root growth was detected more often as an increase in thickness (85.6%) than in length (45.6%). The greatest amount of mineralized tissue inside the canal was observed in the BC group, with statistical significance compared with the HA:CS and P:CS groups (P regenerative procedures in dogs did not improve the formation of new mineralized tissues along the root canal walls or the histologic evidence of the regeneration of a pulp-dentin complex. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. Incompressible Turbulent Wing-Body Junction Flow

    Science.gov (United States)

    Krishnamurthy, R.; Cagle, Corey D.; Chandra, S.

    1998-01-01

    The overall objective of this study is to contribute to the optimized design of fan bypass systems in advanced turbofan engines. Increasing the engine bypass ratios have provided a major boost in engine performance improvement over the last fifty years. An engine with high bypass ratio (11-16:1) such as the Advanced Ducted Propulsion (ADP) is being developed and is expected to provide an additional 25% improvement in overall efficiency over the early turbofans. Such significant improvements in overall efficiency would reduce the cost per seat mile, which is a major government and Industry challenge for the 21th century. The research is part of the Advanced Subsonic Technology (AST) program that involves a NASA, U.S. Industry and FAA partnership with the goal of a safe and highly productive global air transportation system. The immediate objective of the study is to perform numerical simulation of duct-strut interactions to elucidate the loss mechanisms associated with this configuration that is typical of advanced turbofan engines such as ADP. However, at present experimental data for a duct-strut configuration are not available. Thus, as a first step a wing-body junction flow would be studied and is the specific objective of the present study. At the outset it is to be recognized that while duct-strut interaction flow is similar to that of wing-body junction flows, there are some differences owing to the presence of a wall at both ends of the strut. Likewise, some differences are due to the sheared inflow (as opposed to a uniform inflow) velocity profile. It is however expected that some features of a wing-body junction flow would persist. Next, some of the salient aspects of the complex flow near a wing-body junction, as revealed by various studies reported in the literature will be reviewed. One of the principle characteristics of the juncture flow, is the presence of the mean flow components in a plane perpendicular to the direction of the oncoming free

  1. Apical constriction initiates new bud formation during monopodial branching of the embryonic chicken lung

    Science.gov (United States)

    Kim, Hye Young; Varner, Victor D.; Nelson, Celeste M.

    2013-01-01

    Branching morphogenesis sculpts the airway epithelium of the lung into a tree-like structure to conduct air and promote gas exchange after birth. In the avian lung, a series of buds emerges from the dorsal surface of the primary bronchus via monopodial branching to form the conducting airways; anatomically, these buds are similar to those formed by domain branching in the mammalian lung. Here, we show that monopodial branching is initiated by apical constriction of the airway epithelium, and not by differential cell proliferation, using computational modeling and quantitative imaging of embryonic chicken lung explants. Both filamentous actin and phosphorylated myosin light chain were enriched at the apical surface of the airway epithelium during monopodial branching. Consistently, inhibiting actomyosin contractility prevented apical constriction and blocked branch initiation. Although cell proliferation was enhanced along the dorsal and ventral aspects of the primary bronchus, especially before branch formation, inhibiting proliferation had no effect on the initiation of branches. To test whether the physical forces from apical constriction alone are sufficient to drive the formation of new buds, we constructed a nonlinear, three-dimensional finite element model of the airway epithelium and used it to simulate apical constriction and proliferation in the primary bronchus. Our results suggest that, consistent with the experimental results, apical constriction is sufficient to drive the early stages of monopodial branching whereas cell proliferation is dispensable. We propose that initial folding of the airway epithelium is driven primarily by apical constriction during monopodial branching of the avian lung. PMID:23824575

  2. Modeling the Morphometric Evolution of the Maize Shoot Apical Meristem.

    Science.gov (United States)

    Leiboff, Samuel; DeAllie, Christopher K; Scanlon, Michael J

    2016-01-01

    The maize (Zea mays subsp. mays L.) shoot apical meristem (SAM) is a self-replenishing pool of stem cells that produces all above-ground plant tissues. Improvements in image acquisition and processing techniques have allowed high-throughput, quantitative genetic analyses of SAM morphology. As with other large-scale phenotyping efforts, meaningful descriptions of genetic architecture depend on the collection of relevant measures. In this study, we tested two quantitative image processing methods to describe SAM morphology within the genus Zea, represented by 33 wild relatives of maize and 841 lines from a domesticated maize by wild teosinte progenitor (MxT) backcross population, along with previously reported data from several hundred diverse maize inbred lines. Approximating the MxT SAM as a paraboloid derived eight parabolic estimators of SAM morphology that identified highly overlapping quantitative trait loci (QTL) on eight chromosomes, which implicated previously identified SAM morphology candidate genes along with new QTL for SAM morphological variation. Using a Fourier-transform related method of comprehensive shape analysis, we detected cryptic SAM shape variation that identified QTL on six chromosomes. We found that Fourier transform shape descriptors and parabolic estimation measures are highly correlated and identified similar QTL. Analysis of shoot apex contours from 73 anciently diverged plant taxa further suggested that parabolic shape may be a universal feature of plant SAMs, regardless of evolutionary clade. Future high-throughput examinations of SAM morphology may benefit from the ease of acquisition and phenotypic fidelity of modeling the SAM as a paraboloid.

  3. Embryology meets molecular biology: Deciphering the apical ectodermal ridge.

    Science.gov (United States)

    Verheyden, Jamie M; Sun, Xin

    2017-09-15

    More than sixty years ago, while studying feather tracks on the shoulder of the chick embryo, Dr. John Saunders used Nile Blue dye to stain the tissue. There, he noticed a darkly stained line of cells that neatly rims the tip of the growing limb bud. Rather than ignoring this observation, he followed it up by removing this tissue and found that it led to a striking truncation of the limb skeletons. This landmark experiment marks the serendipitous discovery of the apical ectodermal ridge (AER), the quintessential embryonic structure that drives the outgrowth of the limb. Dr. Saunders continued to lead the limb field for the next fifty years, not just through his own work, but also by inspiring the next generation of researchers through his infectious love of science. Together, he and those who followed ushered in the discovery of fibroblast growth factor (FGF) as the AER molecule. The seamless marriage of embryology and molecular biology that led to the decoding of the AER serves as a shining example of how discoveries are made for the rest of the developmental biology field. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Malignant Arrhythmia in Apical Ballooning Syndrome: Risk Factors and Outcomes

    Directory of Open Access Journals (Sweden)

    Samuel J. Asirvatham

    2008-08-01

    Full Text Available Objectives: We sought to determine the frequency and outcomes with symptomatic arrhythmia in patients with apical ballooning syndrome (ABS. Methods: A retrospective review of the Mayo Clinic Angiography database was conducted to identify patients who met the Mayo criteria for ABS. Patients with documented arrhythmias formed the study group, and 31 randomly selected patients with ABS but without arrhythmia formed the control group.Results: Out of 105 patients identified with ABS, 6 (5.7% women aged 69 +/- 9 years experienced significant arrhythmia (ventricular fibrillation, asystole, 2 patients died, and 1 required permanent pacemaker implantation. When compared with controls, the study group showed no significant difference with respect to ECG characteristics (QT, QRS duration or axis except for R-R interval variability (see comments below (30.6±6 vs 14.5±17 p = 0.0004, QTc, and P-R interval. Patients without arrhythmia were more likely to be on beta-blocker therapy than the study population (33% vs 80.6% p = 0.02. Conclusion: Life-threatening arrhythmia is uncommon (5.7% with ABS despite marked, structural abnormalities. When arrhythmias do occur, the outcome is poor. Prominent variability in R-R intervals appears to be predictive of significant arrhythmias in ABS. The role of beta-blocker therapy in preventing arrhythmia with ABS requires further investigation.

  5. Structural development and energy dissipation in simulated silicon apices

    Directory of Open Access Journals (Sweden)

    Samuel Paul Jarvis

    2013-12-01

    Full Text Available In this paper we examine the stability of silicon tip apices by using density functional theory (DFT calculations. We find that some tip structures - modelled as small, simple clusters - show variations in stability during manipulation dependent on their orientation with respect to the sample surface. Moreover, we observe that unstable structures can be revealed by a characteristic hysteretic behaviour present in the F(z curves that were calculated with DFT, which corresponds to a tip-induced dissipation of hundreds of millielectronvolts resulting from reversible structural deformations. Additionally, in order to model the structural evolution of the tip apex within a low temperature NC-AFM experiment, we simulated a repeated tip–surface indentation until the tip structure converged to a stable termination and the characteristic hysteretic behaviour was no longer observed. Our calculations suggest that varying just a single rotational degree of freedom can have as measurable an impact on the tip–surface interaction as a completely different tip structure.

  6. Structural development and energy dissipation in simulated silicon apices.

    Science.gov (United States)

    Jarvis, Samuel Paul; Kantorovich, Lev; Moriarty, Philip

    2013-12-20

    In this paper we examine the stability of silicon tip apices by using density functional theory (DFT) calculations. We find that some tip structures - modelled as small, simple clusters - show variations in stability during manipulation dependent on their orientation with respect to the sample surface. Moreover, we observe that unstable structures can be revealed by a characteristic hysteretic behaviour present in the F(z) curves that were calculated with DFT, which corresponds to a tip-induced dissipation of hundreds of millielectronvolts resulting from reversible structural deformations. Additionally, in order to model the structural evolution of the tip apex within a low temperature NC-AFM experiment, we simulated a repeated tip-surface indentation until the tip structure converged to a stable termination and the characteristic hysteretic behaviour was no longer observed. Our calculations suggest that varying just a single rotational degree of freedom can have as measurable an impact on the tip-surface interaction as a completely different tip structure.

  7. Poda apical para uniformizar a colheita de flores de ?tango?

    Directory of Open Access Journals (Sweden)

    Francine Lorena Cuquel

    1999-01-01

    Full Text Available Este trabalho testou a poda apical das hastes de tango 4 e 6 semanas após a roçada, para homogeneizar a colheita que, comercialmente, necessita ser feita por um período de aproximadamente 5 dias numa mesma área. Foram avaliados altura média das plantas no primeiro dia de colheita, número médio de hastes colhidas/planta e a média do peso de matéria seca colhida/haste. Só foi verificada diferença significativa para altura média das plantas no primeiro dia de colheita, não se conseguindo reduzir o número de colheitas necessárias por planta. Existem indicações de que há necessidade de reduzir a variabilidade genética da população para homogeneizar a colheita de inflorescências de tango.

  8. Radiographic evaluation of apical root resorption following fixed orthodontic treatment

    Directory of Open Access Journals (Sweden)

    Sina Haghanifar

    2012-01-01

    Full Text Available Background and Aims: Apical root resorption is an adverse side effect of fixed orthodontic treatment which cannot be repaired. The aim of this study was to use panoramic radiographs to compare the root resorption before and after the orthodontic treatment with standard edgewise .018 appliance.Materials and Methods: The before and after treatment panoramic views of sixty-three patients needed fixed orthodontic treatment included 1520 teeth were categorized into 3 Grades (G0: without resorption, G1: mild resorption with blunt roots or ≤ 1/4 of root length, G2: moderate to severe resorption or > 1/4 to 1/2 of root length. Relationship between root resorption and sex and treatment duration was analyzed with Mann-whitney and Spearman's correlation coefficient, respectively.Results: The findings showed that 345 teeth were categorized as Grade 1. Grade 2 of root resorption was not found in this study. The highest amount of root resorption was recorded for the mandibular lateral incisor. In both gender, the root resorption of the mandible was more than that of the maxilla. The males showed significantly higher rate of resorption than the females (P0.05.Conclusion: The mandible and male patients showed higher amount of root resorption. In addition, root resorption was not related to the treatment duration and the side of the jaws.

  9. Neuroelectric Tuning of Cortical Oscillations by Apical Dendrites in Loop Circuits

    Directory of Open Access Journals (Sweden)

    David LaBerge

    2017-06-01

    Full Text Available Bundles of relatively long apical dendrites dominate the neurons that make up the thickness of the cerebral cortex. It is proposed that a major function of the apical dendrite is to produce sustained oscillations at a specific frequency that can serve as a common timing unit for the processing of information in circuits connected to that apical dendrite. Many layer 5 and 6 pyramidal neurons are connected to thalamic neurons in loop circuits. A model of the apical dendrites of these pyramidal neurons has been used to simulate the electric activity of the apical dendrite. The results of that simulation demonstrated that subthreshold electric pulses in these apical dendrites can be tuned to specific frequencies and also can be fine-tuned to narrow bandwidths of less than one Hertz (1 Hz. Synchronous pulse outputs from the circuit loops containing apical dendrites can tune subthreshold membrane oscillations of neurons they contact. When the pulse outputs are finely tuned, they function as a local “clock,” which enables the contacted neurons to synchronously communicate with each other. Thus, a shared tuning frequency can select neurons for membership in a circuit. Unlike layer 6 apical dendrites, layer 5 apical dendrites can produce burst firing in many of their neurons, which increases the amplitude of signals in the neurons they contact. This difference in amplitude of signals serves as basis of selecting a sub-circuit for specialized processing (e.g., sustained attention within the typically larger layer 6-based circuit. After examining the sustaining of oscillations in loop circuits and the processing of spikes in network circuits, we propose that cortical functioning can be globally viewed as two systems: a loop system and a network system. The loop system oscillations influence the network system’s timing and amplitude of pulse signals, both of which can select circuits that are momentarily dominant in cortical activity.

  10. Influence of Age and Apical Diameter on the Success of Endodontic Regeneration Procedures.

    Science.gov (United States)

    Estefan, Bishoy Safwat; El Batouty, Kariem Mostafa; Nagy, Mohamed Mokhtar; Diogenes, Anibal

    2016-11-01

    Treatment of immature permanent teeth with necrotic pulp and apical pathosis constitutes a challenge for endodontists. The present study was done to evaluate the effect of age and apical diameter on the regenerative potential of young permanent immature teeth with necrotic pulps. Immature necrotic permanent maxillary incisors (n = 40) of patients 9-18 years old were divided into 2 groups according to the treatment protocol: group Y (younger age group), 9-13 years and group O (older age group), 14-18 years. Each group was further subdivided into 2 subgroups according to apical diameter, subgroup (n) (narrower diameter) between 0.5 and 1 mm and subgroup (w) (wider diameter) equal to or greater than 1 mm. Revascularization procedures were performed for all patients. Follow-up was done for up to 12 months. Standardized radiographs were digitally evaluated for increase in root length and thickness and decrease in apical diameter. After the follow-up period, most of the cases demonstrated radiographic evidence of periapical healing. Group Y showed significant progressive increase in root length and width and decrease in apical diameter. Subgroup (w) representing wider apical diameter showed significant progress as well. It was found that revascularization procedures can be implemented in any age ranging from 9 to 18 years; however, younger age groups were better candidates for revascularization procedure than older ones. Regarding the apical diameter, regeneration procedures were successful with apical diameters as small as 0.5 mm. However, teeth with preoperative wider diameters (≥1 mm) demonstrated greater increase in root thickness, length, and apical narrowing. Copyright © 2016 American Association of Endodontists. All rights reserved.

  11. First-principles methodology for quantum transport in multiterminal junctions.

    Science.gov (United States)

    Saha, Kamal K; Lu, Wenchang; Bernholc, J; Meunier, Vincent

    2009-10-28

    We present a generalized approach for computing electron conductance and I-V characteristics in multiterminal junctions from first-principles. Within the framework of Keldysh theory, electron transmission is evaluated employing an O(N) method for electronic-structure calculations. The nonequilibrium Green function for the nonequilibrium electron density of the multiterminal junction is computed self-consistently by solving Poisson equation after applying a realistic bias. We illustrate the suitability of the method on two examples of four-terminal systems, a radialene molecule connected to carbon chains and two crossed-carbon chains brought together closer and closer. We describe charge density, potential profile, and transmission of electrons between any two terminals. Finally, we discuss the applicability of this technique to study complex electronic devices.

  12. The development of the myotendinous junction. A review.

    Science.gov (United States)

    Charvet, Benjamin; Ruggiero, Florence; Le Guellec, Dominique

    2012-04-01

    The myotendinous junction (MTJ) is a complex specialized region located at the muscle-tendon interface that represents the primary site of force transmission. Despite their different embryologic origins, muscle and tendon morphogenesis occurs in close spatial and temporal association. After muscle attachment, muscle and tendon constitute a dynamic and functional integrated unit that transduces muscle contraction force to the skeletal system. We review here the current understanding of MTJ formation describing changes during morphogenesis and focusing on the crosstalk between muscle and tendon cells that leads to the development of a functional MTJ. Molecules involved in the formation of the linkage, both at the tendon side and at the muscle side of the junction are described. Much of this knowledge comes from studies using different animal models such as mice, zebrafish and Drosophila where powerful methods for in vivo imaging and genetic manipulations can be used to enlighten this developmental process.

  13. Electronic transport through EuO spin filter tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Jutong, Nuttachai; Eckern, Ulrich [Institut fuer Physik, Universitaet Augsburg, 86135 Augsburg (Germany); Rungger, Ivan; Sanvito, Stefano [School of Physics and CRANN, Trinity College Dublin, Dublin (Ireland); Schwingenschloegl, Udo [KAUST, PSE Division, Thuwal 23955-6900, Kingdom of Saudi Arabia (Saudi Arabia)

    2012-07-01

    Spin filter tunnel junctions based on europium monoxide (EuO), a ferromagnetic semiconductor, are investigated by means of density functional theory. In particular, the spin transport of Cu/EuO/Cu junctions is investigated by using the self-consistent ab-initio electron transport code SMEAGOL. The dependence of the transmission coefficient on the interface spacing and on the EuO thickness is studied, and explained in terms of the density of states and the complex band structure of EuO. Our calculation indicates that EuO epitaxially grown on Cu can act as a perfect spin filter, with polarization close to 100%, which is related mainly to the Eu-4f states. The transmission coefficient is sensitive to the interface spacing, since this spacing determines the charge transfer between EuO and the Cu leads.

  14. Formation and stability of ridge-ridge-ridge triple junctions in rheologically realistic lithosphere model

    Science.gov (United States)

    Gerya, Taras; Burov, Evgueni

    2015-04-01

    Triple junctions are probably the most remarkable features of plate boundaries since their presence constitutes one of the major demonstrations of plate tectonics theory. Divergent (R-R-R) triple junctions (at 120° and T junctions) are particular ones since their stability depends on the exact values of the relative velocities of plate divergence and hence is strongly affected by plate rheology and processes of crustal accretion. The mechanisms of their formation and long-term steadiness are not well understood even though it is commonly accepted, generally based on common sense, that the geometry and stability of triple junctions should be related to the intuitively acceptable geometric considerations that 3-branch configurations should be "stable" over the time on a 3D Earth surface. That said, most plate boundaries are in fact 2D in terms that they involve only two plates, while junctions with 3 and more branches, if even mechanically not excluded, are generally short-lived and hence rarely observed at tectonic scale. Indeed, it has been long-time suggested that triple junctions result from evolution of short-lived quadruple junctions, yet, without providing a consistent mechanical explanation or experimental demonstration of this process, due to the rheological complexity of the lithosphere and that of strain localization and crustal accretion processes. For example, it is supposed that R-R-R junctions form as result of axisymmetric mantle upwellings. However, impingement of buoyant fluid on a non-pre-stressed lithosphere should result in multiple radial cracks, as is well known from previous analog and numerical experiments. In case of uni-directionally pre-stressed lithosphere, it has also shown that linear 2D rift structures should be formed. Therefore, a complete 3D thermos-mechanically consistent approach is needed to understand the processes of formation of multi-branch junctions. With this goal we here reproduce and study the processes of multi

  15. DHT deficiency perturbs the integrity of the rat seminiferous epithelium by disrupting tight and adherens junctions.

    Science.gov (United States)

    Kolasa, Agnieszka; Marchlewicz, Mariola; Wenda-Różewicka, Lidia; Wiszniewska, Barbara

    2011-01-01

    In rats with a DHT deficiency induced by finasteride, morphological changes in the seminiferous epithelium were observed. The structural alterations were manifested by the premature germ cells sloughing into the lumen of seminiferous tubules. The etiology of this disorder could be connected with intercellular junctions disintegration. We showed in the immunohistochemical study the changes in expression of some proteins building tight and adherens junctions. The depression of N-cadherin, β-catenin and occludin immunoexpressions could be the reason for the release of immature germ cells from the seminiferous epithelium. However, the observed increase of the immunohistochemical reaction intensity of vinculin, one of the cadherin/catenin complex regulators, could be insufficient to maintain the proper function of adherens junctions. The hormonal imbalance appears to influence the pattern of expression of junctional proteins in the seminiferous epithelium. It could lead to untimely germ cells sloughing, and ultimately could impair fertility.

  16. Identification of RecQL1 as a Holliday junction processing enzyme in human cell lines

    Science.gov (United States)

    LeRoy, Gary; Carroll, Robert; Kyin, Saw; Seki, Masayuki; Cole, Michael D.

    2005-01-01

    Homologous recombination provides an effective way to repair DNA double-strand breaks (DSBs) and is required for genetic recombination. During the process of homologous recombination, a heteroduplex DNA structure, or a ‘Holliday junction’ (HJ), is formed. The movement, or branch migration, of this junction is necessary for recombination to proceed correctly. In prokaryotes, the RecQ protein or the RuvA/RuvB protein complex can promote ATP-dependent branch migration of Holliday junctions. Much less is known about the processing of Holliday junctions in eukaryotes. Here, we identify RecQL1 as a predominant ATP-dependent, HJ branch migrator present in human nuclear extracts. A reduction in the level of RecQL1 induced by RNA interference in HeLa cells leads to an increase in sister chromatid exchange. We propose that RecQL1 is involved in the processing of Holliday junctions in human cells. PMID:16260474

  17. Obturating teeth with wide open apices using mineral trioxide aggregate: a case report.

    Science.gov (United States)

    Levenstein, H

    2002-07-01

    The conventional approach in handling a tooth with a wide open apex requiring endodontic treatment is by means of a procedure called apexification. The objective of treatment is to introduce calcium hydroxide mixed with sterile water or local anaesthetic into the root canal to create a hard-tissue-like formation or an apical plug to prevent extrusion of filling materials during obturation of teeth with wide open apices. This procedure may take anything from 6 months to 2 years. In 1999 a new material called mineral trioxide aggregate (MTA) was introduced to the dental profession for clinical use which has the ability to create an apical plug within a few weeks.

  18. The large GTPase Mx1 is involved in apical transport in MDCK cells.

    Science.gov (United States)

    Hoff, Florian; Greb, Christoph; Hollmann, Christina; Hönig, Ellena; Jacob, Ralf

    2014-09-01

    In epithelial cells apical proteins are transported by specific transport carriers to the correct membrane domain. The composition of these carriers is heterogeneous and comprises components such as motor proteins, annexins, lectins, Rab GTPases and cargo molecules. Here, we provide biochemical and fluorescence microscopic data to show that the dynamin-related large GTPase Mx1 is a component of post-Golgi vesicles carrying the neurotrophin receptor p75(NTR) . Moreover, siRNA-mediated depletion of Mx1 significantly decreased the transport efficiency of apical proteins in MDCK cells. In conclusion, Mx1 plays a crucial role in the delivery of cargo molecules to the apical membrane of epithelial cells.

  19. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  20. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

  1. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the best-studied

  2. Shot noise in YBCO bicrystal Josephson junctions

    DEFF Research Database (Denmark)

    Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.;

    2003-01-01

    We measured spectral noise density in YBCO symmetric bicrystal Josephson junctions on sapphire substrates at bias voltages up to 100 mV and T 4.2 K. Normal state resistance of the Josephson junctions, R-N = 20-90 Omega and ICRN up to 2.2 mV have been observed in the experimental samples. Noise...

  3. A micro-computed tomography study of the negotiation and anatomical feature in apical root canal of mandibular molars.

    Science.gov (United States)

    Min, Yi; Ma, Jing-Zhi; Shen, Ya; Cheung, Gary Shun-Pan; Gao, Yuan

    2016-11-01

    The aim of this study was to investigate the clinical negotiation of various apical anatomic features of the mandibular first molars in a Chinese population using micro-computed tomography (micro-CT). A total of 152 mandibular first molars were scanned with micro-CT at 30 µm resolution. The apical 5 mm of root canal (ARC) was reconstructed three dimensionally and classified. Subsequently, the access cavity was prepared with the ARC anatomy blinded to the operator. The ARC was negotiated with a size 10 K file with or without precurve. Information on the ability to obtain a reproducible glide path was recorded. The anatomical classification of ARC was Type I with 68.45% in mandibular first molars. The negotiation result of ARC with Category i was 387 canals (74.00%). With a bent negotiating file, 96 canals were negotiated, including 88 reproducible glide paths (Category ii) and 8 irregular glide paths (Category iii). About 7.65% canals could not be negotiated with patency successfully (Category iv). The statistical analyze shown the anatomic feature of ARC had effect on the negotiation of ARC (p negotiation. The category of negotiation in ARC would be helpful in the using of NiTi rotary instruments. Negotiation of ARC to the working length with patency should be careful and skillful because of the complexities of ARC. SCANNING 38:819-824, 2016. © 2016 Wiley Periodicals, Inc.

  4. Connective Auxin Transport in the Shoot Facilitates Communication between Shoot Apices.

    Science.gov (United States)

    Bennett, Tom; Hines, Geneviève; van Rongen, Martin; Waldie, Tanya; Sawchuk, Megan G; Scarpella, Enrico; Ljung, Karin; Leyser, Ottoline

    2016-04-01

    The bulk polar movement of the plant signaling molecule auxin through the stem is a long-recognized but poorly understood phenomenon. Here we show that the highly polar, high conductance polar auxin transport stream (PATS) is only part of a multimodal auxin transport network in the stem. The dynamics of auxin movement through stems are inconsistent with a single polar transport regime and instead suggest widespread low conductance, less polar auxin transport in the stem, which we term connective auxin transport (CAT). The bidirectional movement of auxin between the PATS and the surrounding tissues, mediated by CAT, can explain the complex auxin transport kinetics we observe. We show that the auxin efflux carriers PIN3, PIN4, and PIN7 are major contributors to this auxin transport connectivity and that their activity is important for communication between shoot apices in the regulation of shoot branching. We propose that the PATS provides a long-range, consolidated stream of information throughout the plant, while CAT acts locally, allowing tissues to modulate and be modulated by information in the PATS.

  5. Environmental and Pathogenic Factors Inducing Brown Apical Necrosis on Fruit of English (Persian) Walnut.

    Science.gov (United States)

    Scotton, Michele; Bortolin, Enrico; Fiorin, Antonio; Belisario, Alessandra

    2015-11-01

    Brown apical necrosis (BAN) is a most recently described disease affecting English (Persian) walnut fruit. BAN was only recorded in intensively managed walnut orchards and was found to be a disease complex mainly caused by Fusarium species. All fungi associated with this disease are polyphagous and ubiquitous, not specific to walnut. Consequently, BAN occurrence is more strictly dependent, than generally, on the interaction between pathological features and environmental conditions. Environmental variables identified with regression analysis showed that maximum temperature, angle of main wind direction versus tree row orientation, and orchard distance to the closest river/canal, all representative of climatic conditions occurring in the orchard, were related to fruit drop. The factor displaying the highest influence on severity of BAN fruit drop was maximum temperature and only subordinately factors are associated with relative humidity. BAN symptoms were reproduced with in planta artificial inoculation, and fruit drop of symptomatic fruit was significantly higher than that of the noninoculated trees for each type of inoculum (Fusarium semitectum, F. graminearum, and Alternaria spp.). F. semitectum and F. graminearum were more aggressive than Alternaria species, and the earliest artificial inoculations in mid-May resulted in the highest fruit drop. The extension of walnut fruit susceptibility and the conducive environmental factors to BAN are discussed.

  6. New insights in shoot apical meristem morphogenesis: Isotropy comes into play.

    Science.gov (United States)

    Sassi, Massimiliano; Traas, Jan

    2015-01-01

    The great complexity and plasticity of aerial plant shapes largely results from the activity of the shoot apical meristem (SAM), a group of undifferentiated cells which produces all the aboveground organs of the plant. Organogenesis at the SAM is regulated by the hormone auxin, which, through an integration of active transport, signalling and transcriptional regulation, determines the positional and temporal information dictating where, when, and how a new organ will be formed. At the cellular level, the information stemming from the regulatory molecular networks influences the growth of the cells within the tissue to give rise to the final organ shape. The growth of plant cells is mainly controlled by the cell wall, a rigid structure mainly made of polysaccharides, which surrounds the cells and links them together in an organismal continuum. Over the years, several lines of evidence have pointed at a role for the regulation of the elasticity of the cell wall, downstream of auxin action, in the formation of organs at the SAM. We have recently shown that auxin also induces a shift toward isotropic growth by modulating the organization of cortical microtubules in peripheral SAM cells, which promotes organ formation. Here, we discuss our results and identify new hypotheses to drive future research.

  7. T1-nerve root neuroma presenting with apical mass and Horner's syndrome

    Directory of Open Access Journals (Sweden)

    Podnar Simon

    2007-03-01

    Full Text Available Abstract Background The appearance of dumbbell neuroma of the first thoracic root is extremely rare. The extradural component of a T1-dumbbell neuroma may present as an apical mass. The diagnosis of hand weakness is complex and may be delayed in T1-neuroma because of absence of the palpable cervical mass. One-stage removal of a T1-root neuroma and its intrathoracic extension demanded an extended posterior midline approach in the sitting position. Case presentation A 51-year old man had suffered a traumatic partial tendon rupture of his wrist flexor muscles 6 years ago. Since the incident he occasionally felt fullness and tenderness in the affected forearm with some tingling in his fingers bilaterally. During the last two years the hand weakness was continuous and hypotrophy of the medial flexor and intrinsic hand muscles had become apparent. Electrophysiological studies revealed an ulnar neuropathy in addition to mild median and radial nerve dysfunction, including a mild contralateral carpal tunnel syndrome. The diagnostic work-up for multiple mononeuropathy in the upper extremity was negative. Repeated electrophysiological studies revealed fibrillations in the C7 paravertebral muscles on the affected side. Chest x-ray revealed a large round apical mass on the affected side. A Horner's syndrome was noted at this point of diagnostic work-up. MRI of the cervical and thoracic spine revealed a dumbbell T1 neuroma enlarging the intervertebral foramen at T1-2 and a 5 cm large extradural tumor with extension into the apex of the ipsilateral lung. The patient underwent surgery in sitting position using a left dorsal midline approach. Although the T1 root could not be preserved, the patient's neurological condition was unchanged after the surgery. Conclusion Extended posterior midline exposure described here using hemilaminectomy, unilateral facetectomy and costo-transversectomy is efficient and safe for one-stage removal of dumbbell tumors at the T1

  8. Frecuencia de periodontitis apical en tratamientos endodónticos de pregrado Frequency of apical periodontitis in endodontic treatment in undergraduate

    OpenAIRE

    León, P; MJ Ilabaca; Alcota,M; FE González

    2011-01-01

    La periodontitis apical es una enfermedad de los tejidos periapicales de etiología bacteriana. Su tratamiento requiere erradicar los microorganismos del conducto radicular y obturarlo para lograr la reparación posterior. El objetivo de éste trabajo fue determinar la frecuencia de periodontitis apical en la población que asiste a la clínica de Endodoncia de la Facultad de Odontología de la Universidad de Chile y su relación con diferentes variables: diagnóstico específico, edad, sexo, agudas v...

  9. Pulp microbiology of complete teeth with idiopathic apical lesions.

    Directory of Open Access Journals (Sweden)

    Patricia Rodríguez

    2009-11-01

    Full Text Available Introduction: Periapical changes named as lesions, in teeth with full crown integrity and without history of trauma, do not show a clear aetiology. Objective: To determine the presence of microorganisms in pulp dental tissue will clarify the cause of its death and therefore the damage to periodontal tissues. Materials and methods: From people between 10 and 39 years old, 23 teeth were selected. The samples were taken with paper points and 0.8 sterile files, and were transported in VMGA III medium, to be processed in the following 24 hours after they were taken and sowed in Brucella-agar. Results: The most affected teeth were upper central incisors, 43.8%. From the 23 studied teeth, microbiological grow was seen on 20 teeth. The following microorganisms species were identified: Fusobacterium spp., 25%, Eubacterium spp., 15%; Peptostreptococcus spp., 10%; Campylobacter spp., 10%; gram negative enteric bacteria, 10%; Porphyromonas gingivalis, 10%; Prevotella intermedia, 5%; Eikenellia corrodens, 5%; Dialister pneumosintes, 5%; and yeasts, 5%. There was no growing evidence of Actinomyces actinomycetemcomitans, Tanerella forsythensis and Streptococcus β  hemolytic. Discussion and conclusions: Sound pulp dental tissue is sterile; an injury over it will cause its inflammation, degeneration, death and bacterial contamination. Results in the present study clearly show the presence of microorganisms in closed apical dental lesions of endodontic origin. In same manner, it was seen that a great part of microorganisms species found can be regarded as periodontal pathogens. This could suggest a management with an endodontic, a periodontic and a pharmacological combined treatment.

  10. Reaction-diffusion pattern in shoot apical meristem of plants.

    Directory of Open Access Journals (Sweden)

    Hironori Fujita

    Full Text Available A fundamental question in developmental biology is how spatial patterns are self-organized from homogeneous structures. In 1952, Turing proposed the reaction-diffusion model in order to explain this issue. Experimental evidence of reaction-diffusion patterns in living organisms was first provided by the pigmentation pattern on the skin of fishes in 1995. However, whether or not this mechanism plays an essential role in developmental events of living organisms remains elusive. Here we show that a reaction-diffusion model can successfully explain the shoot apical meristem (SAM development of plants. SAM of plants resides in the top of each shoot and consists of a central zone (CZ and a surrounding peripheral zone (PZ. SAM contains stem cells and continuously produces new organs throughout the lifespan. Molecular genetic studies using Arabidopsis thaliana revealed that the formation and maintenance of the SAM are essentially regulated by the feedback interaction between WUSHCEL (WUS and CLAVATA (CLV. We developed a mathematical model of the SAM based on a reaction-diffusion dynamics of the WUS-CLV interaction, incorporating cell division and the spatial restriction of the dynamics. Our model explains the various SAM patterns observed in plants, for example, homeostatic control of SAM size in the wild type, enlarged or fasciated SAM in clv mutants, and initiation of ectopic secondary meristems from an initial flattened SAM in wus mutant. In addition, the model is supported by comparing its prediction with the expression pattern of WUS in the wus mutant. Furthermore, the model can account for many experimental results including reorganization processes caused by the CZ ablation and by incision through the meristem center. We thus conclude that the reaction-diffusion dynamics is probably indispensable for the SAM development of plants.

  11. Genetic control of maize shoot apical meristem architecture.

    Science.gov (United States)

    Thompson, Addie M; Crants, James; Schnable, Patrick S; Yu, Jianming; Timmermans, Marja C P; Springer, Nathan M; Scanlon, Michael J; Muehlbauer, Gary J

    2014-05-22

    The shoot apical meristem contains a pool of undifferentiated stem cells and generates all above-ground organs of the plant. During vegetative growth, cells differentiate from the meristem to initiate leaves while the pool of meristematic cells is preserved; this balance is determined in part by genetic regulatory mechanisms. To assess vegetative meristem growth and genetic control in Zea mays, we investigated its morphology at multiple time points and identified three stages of growth. We measured meristem height, width, plastochron internode length, and associated traits from 86 individuals of the intermated B73 × Mo17 recombinant inbred line population. For meristem height-related traits, the parents exhibited markedly different phenotypes, with B73 being very tall, Mo17 short, and the population distributed between. In the outer cell layer, differences appeared to be related to number of cells rather than cell size. In contrast, B73 and Mo17 were similar in meristem width traits and plastochron internode length, with transgressive segregation in the population. Multiple loci (6-9 for each trait) were mapped, indicating meristem architecture is controlled by many regions; none of these coincided with previously described mutants impacting meristem development. Major loci for height and width explaining 16% and 19% of the variation were identified on chromosomes 5 and 8, respectively. Significant loci for related traits frequently coincided, whereas those for unrelated traits did not overlap. With the use of three near-isogenic lines, a locus explaining 16% of the parental variation in meristem height was validated. Published expression data were leveraged to identify candidate genes in significant regions. Copyright © 2014 Thompson et al.

  12. Chimaerin suppresses Rac1 activation at the apical membrane to maintain the cyst structure.

    Directory of Open Access Journals (Sweden)

    Shunsuke Yagi

    Full Text Available Epithelial organs are made of a well-polarized monolayer of epithelial cells, and their morphology is maintained strictly for their proper functions. Previously, we showed that Rac1 activation is suppressed at the apical membrane in the mature organoid, and that such spatially biased Rac1 activity is required for the polarity maintenance. Here we identify Chimaerin, a GTPase activating protein for Rac1, as a suppressor of Rac1 activity at the apical membrane. Depletion of Chimaerin causes over-activation of Rac1 at the apical membrane in the presence of hepatocyte growth factor (HGF, followed by luminal cell accumulation. Importantly, Chimaerin depletion did not inhibit extension formation at the basal membrane. These observations suggest that Chimaerin functions as the apical-specific Rac1 GAP to maintain epithelial morphology.

  13. Endodontic management of open apex using Biodentine as a novel apical matrix

    National Research Council Canada - National Science Library

    Ambica Khetarpal; Sarika Chaudhary; Sangeeta Talwar; Mahesh Verma

    2014-01-01

      Aim: Endodontic management of open apex using Biodentine as an apical matrix. Summary : An immature tooth with pulpal necrosis and periapical pathology imposes a great difficulty to the endodontist...

  14. Recycling endosomes in apical plasma membrane domain formation and epithelial cell polarity

    NARCIS (Netherlands)

    Golachowska, Magdalena R.; Hoekstra, Dick; van IJzendoorn, Sven C. D.

    2010-01-01

    Recycling endosomes have taken central stage in the intracellular sorting and polarized trafficking of apical and basolateral plasma membrane components. Molecular players in the underlying mechanisms are now emerging, including small GTPases, class V myosins and adaptor proteins. In particular,

  15. Magnetic Resonance Imaging of Transient Left Ventricular Apical Ballooning Related to Emotional Stress: a Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Mu Sook; Choi, Byoung Wook; Choe, Kyu Ok; Chung, Namsik [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2007-02-15

    Transient left ventricular apical ballooning is characterized by transient wall motion abnormalities involving the left ventricular apex and mid-ventricle in the absence of coronary arterial occlusion. A 66-year-old woman presented to the emergency department with chest pain that mimicked acute myocardial infarction. An aortogram showed akinesis from the mid to apical left ventricle with sparing of the basal segments. Four days later, she underwent MRI, which demonstrated characteristic apical contractile dysfunction, the same as the aortogram, without evidence of myocardial infarction on the MRI. Two weeks later, her symptoms were resolved and follow-up echocardiography showed normal ventricular function. We suggest that MRI might be an integrated imaging diagnostic tool for the diagnosis of this syndrome, which demonstrated characteristic apical contractile dysfunction with performing cine MRI, the absence of significant coronary artery stenosis with performing coronary MR angiography and the absence of myocardial infarction with performing contrast enhanced delayed MRI.

  16. Junction conditions of cosmological perturbations

    CERN Document Server

    Tomita, K

    2004-01-01

    The behavior of perturbations is studied in cosmological models which consist of two different homogeneous regions connected in a spherical shell boundary. The junction conditions for the metric perturbations and the displacements of the shell boundary are analyzed and the surface densities of the perturbed energy and momentum in the shell are derived, using Mukohyama's gauge-invariant formalism and the Israel discontinuity condition. In both homogeneous regions the perturbations of scalar, vector and tensor types are expanded using the 3-dimensional harmonic functions, but the model coupling among them is caused in the shell by the inhomogeneity. By treating the perturbations with odd and even parities separately, it is found, however, that we can have consistent displacements and surface densities for given metric parturbations

  17. Cortisol affects tight junction morphology between pavement cells of rainbow trout gills in single-seeded insert culture.

    Science.gov (United States)

    Sandbichler, Adolf Michael; Farkas, Julia; Salvenmoser, Willi; Pelster, Bernd

    2011-12-01

    A primary culture system of rainbow trout gill pavement cells grown on permeable support (single-seeded insert, SSI) was used to examine histological and physiological changes induced by the addition of the corticosteroid hormone cortisol. Pavement cell epithelia were cultured under symmetrical conditions (L15 apical/L15 basolateral) and developed a high transepithelial resistance (TER, 6.84 ± 1.99 kΩ cm(2), mean ± SEM) with a low phenol red diffusion rate (PRD, 0.15 ± 0.03 μmol l(-1)/day). Addition of cortisol to the basolateral compartment increased TER twofold and reduced PRD threefold over a 5-day period. A similar increase in TER could be seen after 24 h apical freshwater (FW) in control cultures. In cortisol-treated cultures FW exposure did not change TER, but PRD increased significantly. Histochemical staining of the cytoskeleton of cells in SSI culture revealed a morphological partitioning into a single mucosal layer of polarized, polygonal cells featuring cortical F-actin rings which were comparable to F-actin rings of epithelial cells on the lamellar and filamental surface, and several unorganized serosal layers of cells with F-actin stress fibers. Addition of cortisol increased cell density by 18% and in the mucosal layer it led to smaller, less polygonal cells with increased height and increased cell contact area. In transmission electron microscopic images two pairs of cytoplasmatic electron-dense structures confining the zonula occludens apically and basally toward the zonula adhaerens were found. Addition of cortisol increased the distance between those paired structures, hence led to deeper tight junctions. The cortisol-induced increase in barrier properties, therefore, involves a structural fortification of the tight junctions which was not generally modified by a short 24-h apical freshwater stress. These results identify cortisol as a regulator of tight junction morphology between pavement cells of euryhaline fish such as the

  18. Proteomic and bioinformatic analysis of epithelial tight junction reveals an unexpected cluster of synaptic molecules

    Directory of Open Access Journals (Sweden)

    Tang Vivian W

    2006-12-01

    Full Text Available Abstract Background Zonula occludens, also known as the tight junction, is a specialized cell-cell interaction characterized by membrane "kisses" between epithelial cells. A cytoplasmic plaque of ~100 nm corresponding to a meshwork of densely packed proteins underlies the tight junction membrane domain. Due to its enormous size and difficulties in obtaining a biochemically pure fraction, the molecular composition of the tight junction remains largely unknown. Results A novel biochemical purification protocol has been developed to isolate tight junction protein complexes from cultured human epithelial cells. After identification of proteins by mass spectroscopy and fingerprint analysis, candidate proteins are scored and assessed individually. A simple algorithm has been devised to incorporate transmembrane domains and protein modification sites for scoring membrane proteins. Using this new scoring system, a total of 912 proteins have been identified. These 912 hits are analyzed using a bioinformatics approach to bin the hits in 4 categories: configuration, molecular function, cellular function, and specialized process. Prominent clusters of proteins related to the cytoskeleton, cell adhesion, and vesicular traffic have been identified. Weaker clusters of proteins associated with cell growth, cell migration, translation, and transcription are also found. However, the strongest clusters belong to synaptic proteins and signaling molecules. Localization studies of key components of synaptic transmission have confirmed the presence of both presynaptic and postsynaptic proteins at the tight junction domain. To correlate proteomics data with structure, the tight junction has been examined using electron microscopy. This has revealed many novel structures including end-on cytoskeletal attachments, vesicles fusing/budding at the tight junction membrane domain, secreted substances encased between the tight junction kisses, endocytosis of tight junction

  19. Isolated left ventricular apical hypoplasia with infundibular pulmonary and aortic stenosis: A rare combination

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Jin Il; Jeong, Yeon Joo; Lee, Gee Won; Choi, Jung Hyun; Lee, Ji Won [Medical Research Institute, Pusan National University Hospital, Busan (Korea, Republic of)

    2013-12-15

    Isolated left ventricular (LV) apical hypoplasia is a rare congenital cardiac anomaly which is not accompanied by other cardiac abnormalities, with the exception of two cases. We report a case of a 33-year-old male patient with isolated LV apical hypoplasia combined with infundibular pulmonary stenosis and aortic stenosis. We review a literature focusing on the characteristic magnetic resonance features and combined cardiac abnormalities.

  20. Descriptive study of apical periodontitis detected in Cone Beam Computed Tomography scans

    OpenAIRE

    MORETI,Lucieni Cristina Trovati; PANZARELLA,Francine Kühl; OLIVEIRA,Marine de; José Luiz Cintra JUNQUEIRA; MANHÃES JÚNIOR,Luiz Roberto

    2016-01-01

    ABSTRACT Objective: To perform a descriptive study in order to evaluate apical periodontitis in endodontically treated teeth using cone beam computed tomography. Methods: Eighty-six exams presenting at least one apical periodontitis were selected and divided into two groups: 1 for the mandible and 2 for the maxilla. All the exams were done using the same cone beam computed tomography with standard acquisition settings. All the images were processed and manipulated using the same software. T...

  1. Effect of needle insertion depth and apical diameter on irrigant extrusion in simulated immature permanent teeth

    Directory of Open Access Journals (Sweden)

    AKSEL Hacer

    2014-09-01

    Full Text Available The aim of this study was to compare the amount of irrigant extrusion in simulated immature permanent teeth when the apical diameter and needle insertion depth were varied. Thirty single-rooted maxillary incisors with straight root canals were selected. The root length was standardized to a length of 9 mm. The teeth were divided into two experimental groups according to the degree of apical enlargement (n = 15. The apices were enlarged to a diameter of 1.10 mm or 1.70 mm by using a #3 or #6 peeso reamer, respectively, to simulate immature teeth. The irrigation solution was applied 2 or 4 mm short of the working length (WL in each experimental group. The glass vial model was used for the collection of extruded irrigant beyond the root apex. A two-way repeated measures analysis of variance test showed that there was no significant difference between different needle insertion depths (2 and 4 mm short of the WL in the group with an apical diameter of 1.70 mm (p > 0.05. In the group with an apical diameter of 1.10 mm, a 32% increase in irrigant extrusion was observed when the needle was positioned at 2 mm (p < 0.05. Regarding the effect of apical diameter, the group with a diameter of 1.70 mm showed more apical extrusion of the irrigant (34% increase for the needle positioned at 2 mm and 68% increase for the needle positioned at 4 mm. It was observed that the needle insertion depth and apical diameter have a significant effect on irrigant extrusion in immature permanent teeth.

  2. The dynamics of soybean leaf and shoot apical meristem transcriptome undergoing floral initiation process.

    Science.gov (United States)

    Wong, Chui E; Singh, Mohan B; Bhalla, Prem L

    2013-01-01

    Flowering process governs seed set and thus affects agricultural productivity. Soybean, a major legume crop, requires short-day photoperiod conditions for flowering. While leaf-derived signal(s) are essential for the photoperiod-induced floral initiation process at the shoot apical meristem, molecular events associated with early floral transition stages in either leaves or shoot apical meristems are not well understood. To provide novel insights into the molecular basis of floral initiation, RNA-Seq was used to characterize the soybean transcriptome of leaf and micro-dissected shoot apical meristem at different time points after short-day treatment. Shoot apical meristem expressed a higher number of transcripts in comparison to that of leaf highlighting greater diversity and abundance of transcripts expressed in the shoot apical meristem. A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified. Most changes in mRNA level occurred after 1short-day treatment. Transcripts involved in mediating responses to stimulus including hormones or in various metabolic processes represent the top enriched GO functional category for the SAM and leaf dataset, respectively. Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch. RNA-Seq analysis of shoot apical meristem and leaf from soybean undergoing floral transition reveal major reprogramming events in leaves and the SAM that point toward hormones gibberellins (GA) and cytokinin as key regulators in the production of systemic flowering signal(s) in leaves. These hormones may form part of the systemic signals in addition to the established florigen, FLOWERING LOCUS T (FT). Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin, cytokinin and GA

  3. The dynamics of soybean leaf and shoot apical meristem transcriptome undergoing floral initiation process.

    Directory of Open Access Journals (Sweden)

    Chui E Wong

    Full Text Available Flowering process governs seed set and thus affects agricultural productivity. Soybean, a major legume crop, requires short-day photoperiod conditions for flowering. While leaf-derived signal(s are essential for the photoperiod-induced floral initiation process at the shoot apical meristem, molecular events associated with early floral transition stages in either leaves or shoot apical meristems are not well understood. To provide novel insights into the molecular basis of floral initiation, RNA-Seq was used to characterize the soybean transcriptome of leaf and micro-dissected shoot apical meristem at different time points after short-day treatment. Shoot apical meristem expressed a higher number of transcripts in comparison to that of leaf highlighting greater diversity and abundance of transcripts expressed in the shoot apical meristem. A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified. Most changes in mRNA level occurred after 1short-day treatment. Transcripts involved in mediating responses to stimulus including hormones or in various metabolic processes represent the top enriched GO functional category for the SAM and leaf dataset, respectively. Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch. RNA-Seq analysis of shoot apical meristem and leaf from soybean undergoing floral transition reveal major reprogramming events in leaves and the SAM that point toward hormones gibberellins (GA and cytokinin as key regulators in the production of systemic flowering signal(s in leaves. These hormones may form part of the systemic signals in addition to the established florigen, FLOWERING LOCUS T (FT. Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin

  4. Frecuencia de periodontitis apical en tratamientos endodónticos de pregrado Frequency of apical periodontitis in endodontic treatment in undergraduate

    Directory of Open Access Journals (Sweden)

    P León

    2011-12-01

    Full Text Available La periodontitis apical es una enfermedad de los tejidos periapicales de etiología bacteriana. Su tratamiento requiere erradicar los microorganismos del conducto radicular y obturarlo para lograr la reparación posterior. El objetivo de éste trabajo fue determinar la frecuencia de periodontitis apical en la población que asiste a la clínica de Endodoncia de la Facultad de Odontología de la Universidad de Chile y su relación con diferentes variables: diagnóstico específico, edad, sexo, agudas vs. crónicas, éxito/fracaso del tratamiento y rehabilitación post-tratamiento. Se recolectó información de 292 dientes de pacientes tratados en dicha clínica, analizándose la información de aquellos con dientes diagnosticados con algún tipo de periodontitis apical clasificándolo según la nueva nomenclatura de la asociación de endodoncia americana. La frecuencia de periodontitis apical fue de un 36.7% (92 pacientes, de los cuales un 77.8% presentaron patologías de tipo crónicas. Un 75% de los pacientes pertenecieron al sexo femenino y la 5ta década representó un 34.8% de los pacientes. El 100% de los pacientes que acudieron a control presentó éxito en sus tratamientos según variables clínico-radiográficas, mientras que la restauración más frecuente post-tratamiento fue la resina compuesta (52.4%. Dado el pequeño número de pacientes que concurrieron a la citación de control para determinar el éxito del tratamiento, esta variable debe ser considerada como preliminar. Nuestros resultados mostraron que la condición mas frecuente fue la periodontitis apical de tipo crónica, afectando más a mujeres y a la 5ta década.Apical periodontitis is a microbially induced inflammatory disease of the periapical tissues. Its treatment requires eliminating microorganism from root canal and sealing it properly to induce further tissue repair. The aim of this study was to determine the frequency of apical periodontitis and its distribution by

  5. Bioengineering a Single-Protein Junction.

    Science.gov (United States)

    Ruiz, Marta P; Aragones, Albert C; Camarero, Nuria; Vilhena, J G; Ortega, Maria; Zotti, Linda Angela; Perez, Ruben; Cuevas, Juan Carlos; Gorostiza, Pau; Díez-Pérez, Ismael

    2017-10-05

    Bioelectronics moves towards designing nanoscale electronic platforms that allow in vivo determinations. Such devices require interfacing complex biomolecular moieties as the sensing units to an electronic platform for signal transduction. Inevitably, a systematic design goes through a bottom-up understanding of the structurally related electrical signatures of the biomolecular circuit, which will ultimately lead us to tailor its electrical properties. Toward this aim, we show here the first example of bioengineered charge transport in a single-protein electrical contact. The results reveal that a single point-site mutation at the docking hydrophobic patch of a Cu-Azurin causes minor structural distortion of the protein blue Cu site and a dramatic change in the charge transport regime of the single-protein contact, which goes from the classical Cu-mediated 2-step transport in this system to a direct coherent tunneling. Our extensive spectroscopic studies and molecular-dynamics simulations show that the proteins' folding structures are preserved in the single-protein junction. The DFT-computed frontier orbital of the relevant protein segments suggests that the Cu center participation in each protein variant accounts for the different observed charge transport behavior. This work is a direct evidence of charge transport control in a protein backbone through external mutagenesis and a unique nanoscale platform to study structurally related biological electron transfer.

  6. Spin-crossover molecule based thermoelectric junction

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Dibyajyoti [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); Parida, Prakash [Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg (Germany); Pati, Swapan K. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2015-05-11

    Using ab-initio numerical methods, we explore the spin-dependent transport and thermoelectric properties of a spin-crossover molecule (i.e., iron complex of 2-(1H-pyrazol-1-yl)-6-(1H-tetrazole-5-yl)pyridine) based nano-junction. We demonstrate a large magnetoresistance, efficient conductance-switching, and spin-filter activity in this molecule-based two-terminal device. The spin-crossover process also modulates the thermoelectric entities. It can efficiently switch the magnitude as well as spin-polarization of the thermocurrent. We find that thermocurrent is changed by ∼4 orders of magnitude upon spin-crossover. Moreover, it also substantially affects the thermopower and consequently, the device shows extremely efficient spin-crossover magnetothermopower generation. Furthermore, by tuning the chemical potential of electrodes into a certain range, a pure spin-thermopower can be achieved for the high-spin state. Finally, the reasonably large values of figure-of-merit in the presence and absence of phonon demonstrate a large heat-to-voltage conversion efficiency of the device. We believe that our study will pave an alternative way of tuning the transport and thermoelectric properties through the spin-crossover process and can have potential applications in generation of spin-dependent current, information storage, and processing.

  7. Vibrationally coupled electron transport through single-molecule junctions

    Energy Technology Data Exchange (ETDEWEB)

    Haertle, Rainer

    2012-04-26

    vibrational effects have a profound influence on the transport characteristics of a single-molecule contact and play therefore a fundamental role in this transport problem. Our findings demonstrate that vibrationally coupled electron transport through a molecular junction involves two types of processes: (i) transport processes, where an electron tunnels through the molecular bridge from one lead to the other, and (ii) electron-hole pair creation processes, where an electron tunnels from one of the leads onto the molecular bridge and back to the same lead again. Transport processes directly contribute to the electrical current flowing through a molecular contact and involve both excitation and deexcitation processes of the vibrational modes of the junction. Electron-hole pair creation processes do not directly contribute to the electrical current and typically involve only deexcitation processes. Nevertheless, they constitute a cooling mechanism for the vibrational modes of a single-molecule junction that is as important as cooling by transport processes. As the level of vibrational excitation determines the efficiency of electron transport processes, they have an indirect influence on the electrical current flowing through the junction. As we show, however, this influence can be substantial, in particular, if the molecule is coupled asymmetrically to the leads. Accounting for all these processes and their complex interrelationship, we analyze a number of intriguing transport phenomena, including rectification, negative differential resistance, anomalous peak broadening, mode-selective vibrational excitation and vibrationally induced decoherence. Moreover, we show that higher levels of vibrational excitation are obtained for weaker electronic-vibrational coupling. Thus, based on physical grounds, we establish a relation between the weak electronic-vibrational coupling limit and the limit of large bias voltages, where the level of vibrational excitation in a molecular junction

  8. Calcium-enriched mixture cement as artificial apical barrier: A case series

    Directory of Open Access Journals (Sweden)

    Ali Nosrat

    2011-01-01

    Full Text Available In comparison to the conventional apexification using calcium hydroxide, artificial apical barrier technique is more valuable and less time consuming. This article describes successful use of calcium-enriched mixture (CEM cement as an artificial apical barrier in open apices. In this study, 13 single-rooted teeth with necrotic pulps and open apices were treated non-surgically. After copious irrigation of the root canals with NaOCl 5.25% and gentle filing, based on need for interappointment dressing, treatments were followed by CEM cement (BioniqueDent, Tehran, Iran apical plug insertion in the first or second appointment. All cases were then permanently restored. All subjects were followed until radiographic evidence of periradicular healing was seen (mean 14.5 months. Clinically, all cases were functional and asymptomatic and complete osseous healing was observed in all the teeth. Considering the biological properties of CEM cement, this new endodontic biomaterial might be appropriate to be used as artificial apical barrier in the open apex teeth.

  9. Top 50 most-cited articles on craniovertebral junction surgery.

    Science.gov (United States)

    Alan, Nima; Cohen, Jonathan Andrew; Zhou, James; Pease, Matthew; Kanter, Adam S; Okonkwo, David O; Hamilton, David Kojo

    2017-01-01

    Craniovertebral junction is a complex anatomical location posing unique challenges to the surgical management of its pathologies. We aimed to identify the fifty most-cited articles that are dedicated to this field. A keyword search using the Thomson Reuters Web of Knowledge was conducted to identify articles relevant to the field of craniovertebral junction surgery. The articles were reviewed based on title, abstract, and methods, if necessary, and then ranked based on the total number of citations to identify the fifty most-cited articles. Characteristics of the articles were determined and analyzed. The earliest top-cited article was published in 1948. When stratified by decade, 1990s was the most productive with 16 articles. The most-cited article was by Anderson and Dalonzo on a classification of odontoid fractures. By citation rate, the most-cited article was by Herms and Melcher who described Goel's technique of atlantoaxial fixation using C1 lateral mass screws and C2 pedicle screws with rod fixation. Atlantoaxial fixation was the most common topic. The United States, Barrow Neurological Institute, and VH Sonntag were the most represented country, institute, and author, respectively. The significant majority of articles were designed as case series providing level IV evidence. Using citation analysis, we have provided a list of the most-cited articles representing important contributions of various authors from many institutions across the world to the field of craniovertebral junction surgery.

  10. Top 50 most-cited articles on craniovertebral junction surgery

    Science.gov (United States)

    Alan, Nima; Cohen, Jonathan Andrew; Zhou, James; Pease, Matthew; Kanter, Adam S; Okonkwo, David O; Hamilton, David Kojo

    2017-01-01

    Background: Craniovertebral junction is a complex anatomical location posing unique challenges to the surgical management of its pathologies. We aimed to identify the fifty most-cited articles that are dedicated to this field. Methods: A keyword search using the Thomson Reuters Web of Knowledge was conducted to identify articles relevant to the field of craniovertebral junction surgery. The articles were reviewed based on title, abstract, and methods, if necessary, and then ranked based on the total number of citations to identify the fifty most-cited articles. Characteristics of the articles were determined and analyzed. Results: The earliest top-cited article was published in 1948. When stratified by decade, 1990s was the most productive with 16 articles. The most-cited article was by Anderson and Dalonzo on a classification of odontoid fractures. By citation rate, the most-cited article was by Herms and Melcher who described Goel's technique of atlantoaxial fixation using C1 lateral mass screws and C2 pedicle screws with rod fixation. Atlantoaxial fixation was the most common topic. The United States, Barrow Neurological Institute, and VH Sonntag were the most represented country, institute, and author, respectively. The significant majority of articles were designed as case series providing level IV evidence. Conclusion: Using citation analysis, we have provided a list of the most-cited articles representing important contributions of various authors from many institutions across the world to the field of craniovertebral junction surgery. PMID:28250633

  11. Symposia for a Meeting on Ion Channels and Gap Junctions

    CERN Document Server

    Sáez, Juan

    1997-01-01

    Ion channels allow us to see nature in all its magnificence, to hear a Bach suite, to smell the aroma of grandmother's cooking, and, in this regard, they put us in contact with the external world. These ion channels are protein molecules located in the cell membrane. In complex organisms, cells need to communicate in order to know about their metabolic status and to act in a coordinate manner. The latter is also accomplished by a class of ion channels able to pierce the lipid bilayer membranes of two adjacent cells. These intercellular channels are the functional subunits of gap junctions. Accordingly, the book is divided in two parts: the first part is dedicated to ion channels that look to the external world, and the second part is dedicated to gap junctions found at cell interfaces. This book is based on a series of symposia for a meeting on ion channels and gap junctions held in Santiago, Chile, on November 28-30, 1995. The book should be useful to graduate students taking the first steps in this field as...

  12. Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family

    Directory of Open Access Journals (Sweden)

    Balda Maria S

    2009-12-01

    Full Text Available Abstract Background Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is still not well understood and will require a complete understanding of the molecular composition of the junction. Results Here we identify a new transmembrane component of tight junctions: MarvelD3, a four-span transmembrane protein. Its predicted transmembrane helices form a Marvel (MAL and related proteins for vesicle traffic and membrane link domain, a structural motif originally discovered in proteins involved in membrane apposition and fusion events, such as the tight junction proteins occludin and tricellulin. In mammals, MarvelD3 is expressed as two alternatively spliced isoforms. Both isoforms exhibit a broad tissue distribution and are expressed by different types of epithelial as well as endothelial cells. MarvelD3 co-localises with occludin at tight junctions in intestinal and corneal epithelial cells. RNA interference experiments in Caco-2 cells indicate that normal MarvelD3 expression is not required for the formation of functional tight junctions but depletion results in monolayers with increased transepithelial electrical resistance. Conclusions Our data indicate that MarvelD3 is a third member of the tight junction-associated occludin family of transmembrane proteins. Similar to occludin, normal expression of MarvelD3 is not essential for the formation of functional tight junctions. However, MarvelD3 functions as a determinant of epithelial paracellular permeability properties.

  13. Coordinate transformation in the model of long Josephson junctions: geometrically equivalent Josephson junctions

    Science.gov (United States)

    Semerdzhieva, E. G.; Boyadzhiev, T. L.; Shukrinov, Yu. M.

    2005-10-01

    The transition from the model of a long Josephson junction of variable width to the model of a junction with a coordinate-dependent Josephson current amplitude is effected through a coordinate transformation. This establishes the correspondence between the classes of Josephson junctions of variable width and quasi-one-dimensional junctions with a variable thickness of the barrier layer. It is shown that for a junction of exponentially varying width the barrier layer of the equivalent quasi-one-dimensional junction has a distributed resistive inhomogeneity that acts as an attractor for magnetic flux vortices. The curve of the critical current versus magnetic field for a Josephson junction with a resistive microinhomogeneity is constructed with the aid of a numerical simulation, and a comparison is made with the critical curve of a junction of exponentially varying width. The possibility of replacing a distributed inhomogeneity in a Josephson junction by a local inhomogeneity at the end of the junction is thereby demonstrated; this can have certain advantages from a technological point of view.

  14. Atomically Abrupt Topological p-n Junction.

    Science.gov (United States)

    Kim, Sung Hwan; Jin, Kyung-Hwan; Kho, Byung Woo; Park, Byeong-Gyu; Liu, Feng; Kim, Jun Sung; Yeom, Han Woong

    2017-08-24

    Topological insulators (TI's) are a new class of quantum matter with extraordinary surface electronic states, which bear great potential for spintronics and error-tolerant quantum computing. In order to put a TI into any practical use, these materials need to be fabricated into devices whose basic units are often p-n junctions. Interesting electronic properties of a 'topological' p-n junction were proposed theoretically such as the junction electronic state and the spin rectification. However, the fabrication of a lateral topological p-n junction has been challenging because of materials, process, and fundamental reasons. Here, we demonstrate an innovative approach to realize a p-n junction of topological surface states (TSS's) of a three-dimensional (3D) topological insulator (TI) with an atomically abrupt interface. When a ultrathin Sb film is grown on a 3D TI of Bi2Se3 with a typical n-type TSS, the surface develops a strongly p-type TSS through the substantial hybridization between the 2D Sb film and the Bi2Se3 surface. Thus, the Bi2Se3 surface covered partially with Sb films bifurcates into areas of n- and p-type TSS's as separated by atomic step edges with a lateral electronic junction of as short as 2 nm. This approach opens a different avenue toward various electronic and spintronic devices based on well-defined topological p-n junctions with the scalability down to atomic dimensions.

  15. Gap junction communication in myelinating glia.

    Science.gov (United States)

    Nualart-Marti, Anna; Solsona, Carles; Fields, R Douglas

    2013-01-01

    Gap junction communication is crucial for myelination and axonal survival in both the peripheral nervous system (PNS) and central nervous system (CNS). This review examines the different types of gap junctions in myelinating glia of the PNS and CNS (Schwann cells and oligodendrocytes respectively), including their functions and involvement in neurological disorders. Gap junctions mediate intercellular communication among Schwann cells in the PNS, and among oligodendrocytes and between oligodendrocytes and astrocytes in the CNS. Reflexive gap junctions mediating transfer between different regions of the same cell promote communication between cellular compartments of myelinating glia that are separated by layers of compact myelin. Gap junctions in myelinating glia regulate physiological processes such as cell growth, proliferation, calcium signaling, and participate in extracellular signaling via release of neurotransmitters from hemijunctions. In the CNS, gap junctions form a glial network between oligodendrocytes and astrocytes. This transcellular communication is hypothesized to maintain homeostasis by facilitating restoration of membrane potential after axonal activity via electrical coupling and the re-distribution of potassium ions released from axons. The generation of transgenic mice for different subsets of connexins has revealed the contribution of different connexins in gap junction formation and illuminated new subcellular mechanisms underlying demyelination and cognitive defects. Alterations in metabolic coupling have been reported in animal models of X-linked Charcot-Marie-Tooth disease (CMTX) and Pelizaeus-Merzbarcher-like disease (PMLD), which are caused by mutations in the genes encoding for connexin 32 and connexin 47 respectively. Future research identifying the expression and regulation of gap junctions in myelinating glia is likely to provide a better understanding of myelinating glia in nervous system function, plasticity, and disease. This

  16. Incidence of apical root cracks and apical dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths

    NARCIS (Netherlands)

    Liu, R.; Kaiwar, A.; Shemesh, H.; Wesselink, P.R.; Hou, B.; Wu, M.K.

    2013-01-01

    Introduction The aim of this study was to compare the incidence of apical root cracks and dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths. Methods Two hundred forty mandibular incisors were mounted in resin blocks with simulated periodonta

  17. The Ly6 protein coiled is required for septate junction and blood brain barrier organisation in Drosophila.

    Directory of Open Access Journals (Sweden)

    Assia Hijazi

    Full Text Available BACKGROUND: Genetic analysis of the Drosophila septate junctions has greatly contributed to our understanding of the mechanisms controlling the assembly of these adhesion structures, which bear strong similarities with the vertebrate tight junctions and the paranodal septate junctions. These adhesion complexes share conserved molecular components and have a common function: the formation of paracellular barriers restraining the diffusion of solutes through epithelial and glial envelopes. METHODOLOGY/PRINCIPAL FINDINGS: In this work we characterise the function of the Drosophila cold gene, that codes for a protein belonging to the Ly6 superfamily of extracellular ligands. Analysis of cold mutants shows that this gene is specifically required for the organisation of the septate junctions in epithelial tissues and in the nervous system, where its contribution is essential for the maintenance of the blood-brain barrier. We show that cold acts in a cell autonomous way, and we present evidence indicating that this protein could act as a septate junction component. CONCLUSION/SIGNIFICANCE: We discuss the specific roles of cold and three other Drosophila members of the Ly6 superfamily that have been shown to participate in a non-redundant way in the process of septate junction assembly. We propose that vertebrate Ly6 proteins could fulfill analogous roles in tight junctions and/or paranodal septate junctions.

  18. Dissection of neuronal gap junction circuits that regulate social behavior in Caenorhabditis elegans

    Science.gov (United States)

    Jang, Heeun; Levy, Sagi; Flavell, Steven W.; Mende, Fanny; Latham, Richard; Zimmer, Manuel; Bargmann, Cornelia I.

    2017-01-01

    A hub-and-spoke circuit of neurons connected by gap junctions controls aggregation behavior and related behavioral responses to oxygen, pheromones, and food in Caenorhabditis elegans. The molecular composition of the gap junctions connecting RMG hub neurons with sensory spoke neurons is unknown. We show here that the innexin gene unc-9 is required in RMG hub neurons to drive aggregation and related behaviors, indicating that UNC-9–containing gap junctions mediate RMG signaling. To dissect the circuit in detail, we developed methods to inhibit unc-9–based gap junctions with dominant-negative unc-1 transgenes. unc-1(dn) alters a stomatin-like protein that regulates unc-9 electrical signaling; its disruptive effects can be rescued by a constitutively active UNC-9::GFP protein, demonstrating specificity. Expression of unc-1(dn) in RMG hub neurons, ADL or ASK pheromone-sensing neurons, or URX oxygen-sensing neurons disrupts specific elements of aggregation-related behaviors. In ADL, unc-1(dn) has effects opposite to those of tetanus toxin light chain, separating the roles of ADL electrical and chemical synapses. These results reveal roles of gap junctions in a complex behavior at cellular resolution and provide a tool for similar exploration of other gap junction circuits. PMID:28143932

  19. Pre-crash scenarios at road junctions: A clustering method for car crash data.

    Science.gov (United States)

    Nitsche, Philippe; Thomas, Pete; Stuetz, Rainer; Welsh, Ruth

    2017-08-22

    Given the recent advancements in autonomous driving functions, one of the main challenges is safe and efficient operation in complex traffic situations such as road junctions. There is a need for comprehensive testing, either in virtual simulation environments or on real-world test tracks. This paper presents a novel data analysis method including the preparation, analysis and visualization of car crash data, to identify the critical pre-crash scenarios at T- and four-legged junctions as a basis for testing the safety of automated driving systems. The presented method employs k-medoids to cluster historical junction crash data into distinct partitions and then applies the association rules algorithm to each cluster to specify the driving scenarios in more detail. The dataset used consists of 1056 junction crashes in the UK, which were exported from the in-depth "On-the-Spot" database. The study resulted in thirteen crash clusters for T-junctions, and six crash clusters for crossroads. Association rules revealed common crash characteristics, which were the basis for the scenario descriptions. The results support existing findings on road junction accidents and provide benchmark situations for safety performance tests in order to reduce the possible number parameter combinations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Fluxon dynamics in three stacked Josephson junctions

    DEFF Research Database (Denmark)

    Gorria, Carlos; Christiansen, Peter Leth; Gaididei, Yuri Borisovich

    2002-01-01

    /sub -/, the coupling between junctions leads to a repulsion of the fluxons with the same polarity. Above this critical velocity a fluxon will induce radiation in the neighboring junctions, leading to a bunching of the fluxons in the stacked junctions. Using the Sakai-Bodin-Pedersen model, three coupled perturbed sine......-Gordon equations are numerically studied for different values of coupling, damping, and bias parameters. In a narrow range of velocities bunching occurs. Outside this interval the fluxons split and new fluxons may be created. I-V characteristics are presented...

  1. Temperature dependence of thermopower in molecular junctions

    Science.gov (United States)

    Kim, Youngsang; Lenert, Andrej; Meyhofer, Edgar; Reddy, Pramod

    2016-07-01

    The thermoelectric properties of molecular junctions are of considerable interest due to their promise for efficient energy conversion. While the dependence of thermoelectric properties of junctions on molecular structure has been recently studied, their temperature dependence remains unexplored. Using a custom built variable temperature scanning tunneling microscope, we measured the thermopower and electrical conductance of individual benzenedithiol junctions over a range of temperatures (100 K-300 K). We find that while the electrical conductance is independent of temperature, the thermopower increases linearly with temperature, confirming the predictions of the Landauer theory.

  2. Phase qubits fabricated with trilayer junctions

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M; Bialczak, R C; Lenander, M; Lucero, E; Mariantoni, Matteo; Neeley, M; O' Connell, A D; Sank, D; Wang, H; Wenner, J; Yamamoto, T; Yin, Y; Cleland, A N; Martinis, J, E-mail: martin.weides@nist.gov, E-mail: martinis@physics.ucsb.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

    2011-05-15

    We have developed a novel Josephson junction geometry with minimal volume of lossy isolation dielectric, suitable for higher quality trilayer junctions implemented in qubits. The junctions are based on in situ deposited trilayers with thermal tunnel oxide, have micron-sized areas and a low subgap current. In qubit spectroscopy only a few avoided level crossings are observed, and the measured relaxation time of T{sub 1{approx}}400 ns is in good agreement with the usual phase qubit decay time, indicating low loss due to the additional isolation dielectric.

  3. Transcobalamin derived from bovine milk stimulates apical uptake of vitamin B12 into human intestinal epithelial cells.

    Science.gov (United States)

    Hine, Brad; Boggs, Irina; Green, Ralph; Miller, Joshua W; Hovey, Russell C; Humphrey, Rex; Wheeler, Thomas T

    2014-11-01

    Intestinal uptake of vitamin B12 (hereafter B12) is impaired in a significant proportion of the human population. This impairment is due to inherited or acquired defects in the expression or function of proteins involved in the binding of diet-derived B12 and its uptake into intestinal cells. Bovine milk is an abundant source of bioavailable B12 wherein it is complexed with transcobalamin. In humans, transcobalamin functions primarily as a circulatory protein, which binds B12 following its absorption and delivers it to peripheral tissues via its cognate receptor, CD320. In the current study, the transcobalamin-B12 complex was purified from cows' milk and its ability to stimulate uptake of B12 into cultured bovine, mouse and human cell lines was assessed. Bovine milk-derived transcobalamin-B12 complex was absorbed by all cell types tested, suggesting that the uptake mechanism is conserved across species. Furthermore, the complex stimulated the uptake of B12 via the apical surface of differentiated Caco-2 human intestinal epithelial cells. These findings suggest the presence of an alternative transcobalamin-mediated uptake pathway for B12 in the human intestine other than that mediated by the gastric glycoprotein, intrinsic factor. Our findings highlight the potential for transcobalamin-B12 complex derived from bovine milk to be used as a natural bioavailable alternative to orally administered free B12 to overcome B12 malabsorption.

  4. Connexins: a myriad of functions extending beyond assembly of gap junction channels

    Directory of Open Access Journals (Sweden)

    Mroue Rana M

    2009-03-01

    Full Text Available Abstract Connexins constitute a large family of trans-membrane proteins that allow intercellular communication and the transfer of ions and small signaling molecules between cells. Recent studies have revealed complex translational and post-translational mechanisms that regulate connexin synthesis, maturation, membrane transport and degradation that in turn modulate gap junction intercellular communication. With the growing myriad of connexin interacting proteins, including cytoskeletal elements, junctional proteins, and enzymes, gap junctions are now perceived, not only as channels between neighboring cells, but as signaling complexes that regulate cell function and transformation. Connexins have also been shown to form functional hemichannels and have roles altogether independent of channel functions, where they exert their effects on proliferation and other aspects of life and death of the cell through mostly-undefined mechanisms. This review provides an updated overview of current knowledge of connexins and their interacting proteins, and it describes connexin modulation in disease and tumorigenesis.

  5. Connexins: a myriad of functions extending beyond assembly of gap junction channels.

    Science.gov (United States)

    Dbouk, Hashem A; Mroue, Rana M; El-Sabban, Marwan E; Talhouk, Rabih S

    2009-03-12

    Connexins constitute a large family of trans-membrane proteins that allow intercellular communication and the transfer of ions and small signaling molecules between cells. Recent studies have revealed complex translational and post-translational mechanisms that regulate connexin synthesis, maturation, membrane transport and degradation that in turn modulate gap junction intercellular communication. With the growing myriad of connexin interacting proteins, including cytoskeletal elements, junctional proteins, and enzymes, gap junctions are now perceived, not only as channels between neighboring cells, but as signaling complexes that regulate cell function and transformation. Connexins have also been shown to form functional hemichannels and have roles altogether independent of channel functions, where they exert their effects on proliferation and other aspects of life and death of the cell through mostly-undefined mechanisms. This review provides an updated overview of current knowledge of connexins and their interacting proteins, and it describes connexin modulation in disease and tumorigenesis.

  6. Release of Apical Dominance in Potato Tuber Is Accompanied by Programmed Cell Death in the Apical Bud Meristem[C][W

    Science.gov (United States)

    Teper-Bamnolker, Paula; Buskila, Yossi; Lopesco, Yael; Ben-Dor, Shifra; Saad, Inbal; Holdengreber, Vered; Belausov, Eduard; Zemach, Hanita; Ori, Naomi; Lers, Amnon; Eshel, Dani

    2012-01-01

    Potato (Solanum tuberosum) tuber, a swollen underground stem, is used as a model system for the study of dormancy release and sprouting. Natural dormancy release, at room temperature, is initiated by tuber apical bud meristem (TAB-meristem) sprouting characterized by apical dominance (AD). Dormancy is shortened by treatments such as bromoethane (BE), which mimics the phenotype of dormancy release in cold storage by inducing early sprouting of several buds simultaneously. We studied the mechanisms governing TAB-meristem dominance release. TAB-meristem decapitation resulted in the development of increasing numbers of axillary buds with time in storage, suggesting the need for autonomous dormancy release of each bud prior to control by the apical bud. Hallmarks of programmed cell death (PCD) were identified in the TAB-meristems during normal growth, and these were more extensive when AD was lost following either extended cold storage or BE treatment. Hallmarks included DNA fragmentation, induced gene expression of vacuolar processing enzyme1 (VPE1), and elevated VPE activity. VPE1 protein was semipurified from BE-treated apical buds, and its endogenous activity was fully inhibited by a cysteinyl aspartate-specific protease-1-specific inhibitor N-Acetyl-Tyr-Val-Ala-Asp-CHO (Ac-YVAD-CHO). Transmission electron microscopy further revealed PCD-related structural alterations in the TAB-meristem of BE-treated tubers: a knob-like body in the vacuole, development of cytoplasmic vesicles, and budding-like nuclear segmentations. Treatment of tubers with BE and then VPE inhibitor induced faster growth and recovered AD in detached and nondetached apical buds, respectively. We hypothesize that PCD occurrence is associated with the weakening of tuber AD, allowing early sprouting of mature lateral buds. PMID:22362870

  7. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions.

    Science.gov (United States)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin; Kjølbye, Anne-Louise; Hennan, James K; Holstein-Rathlou, Niels-Henrik; Petersen, Jørgen Søberg; Nielsen, Morten Schak

    2007-03-01

    Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes. In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs and by interfering with the gating of gap junctional channels.

  8. Highlighting Kathleen Green and Mario Delmar, guest editors of special issue (part 2): junctional targets of skin and heart disease.

    Science.gov (United States)

    Cowin, Pamela

    2014-06-01

    Cell Communication and Adhesion has been fortunate to enlist two pioneers of epidermal and cardiac cell junctions, Kathleen Green and Mario Delmar, as Guest Editors of a two part series on junctional targets of skin and heart disease. Part 2 of this series begins with an overview from Dipal Patel and Kathy Green comparing epidermal desmosomes to cardiac area composita junctions, and surveying the pathogenic mechanisms resulting from mutations in their components in heart disease. This is followed by a review from David Kelsell on the role of desmosomal mutation in inherited syndromes involving skin fragility. Agnieszka Kobeliak discusses how structural deficits in the epidermal barrier intersect with the NFkB signaling pathway to induce inflammatory diseases such as psoriasis and atopic dermatitis. Farah Sheikh reviews the specialized junctional components in cardiomyocytes of the cardiac conduction system and Robert Gourdie discusses how molecular complexes between sodium channels and gap junction proteins within the perijunctional microdomains within the intercalated disc facilitate conduction. Glenn Radice evaluates the role of N-cadherin in heart. Andre Kleber and Chris Chen explore new approaches to study junctional mechanotransduction in vitro with a focus on the effects of connexin ablation and the role of cadherins, respectively. To complement this series of reviews, we have interviewed Werner Franke, whose systematic documentation the tissue-specific complexity of desmosome composition and pioneering discovery of the cardiac area composita junction greatly facilitated elucidation of the role of desmosomal components in the pathophysiology of human heart disease.

  9. Ex vivo accuracy of three electronic apex locators using different apical file sizes.

    Science.gov (United States)

    Vasconcelos, Bruno Carvalho de; Matos, Leonardo de Alencar; Pinheiro-Júnior, Elilton Cavalcante; Menezes, Antônio Sérgio Teixeira de; Vivacqua-Gomes, Nilton

    2012-01-01

    This study evaluated the accuracy of three electronic apex locators (Root ZX, Novapex, and Justy II) in root canal length determinations using different apical file sizes, considering the apical constriction (AC) and the major foramen (MF) as anatomic references. The diameter of the apical foramina of 40 single-rooted teeth was determined by direct visual measurement and the master apical file was established. Electronic measurements were then performed using 3 instruments: the selected master apical file (adjusted file), one size smaller (intermediate file), and two sizes smaller (misfit file). The distances from the tip of files fixed in the canals to the MF and to the AC were measured digitally. Precision at AC and at MF for the misfit, intermediate and adjusted apical files was as follows: 80%/88%/83% and 78%/83%/95% (Root ZX); 80%/85%/80% and 68%/73%/73% (Novapex); and 78%/80%/78% and 65%/78%/70% (Justy II). Considering the mean discrepancies, statistically significant differences were found only for the adjusted file at MF, with Root ZX presenting the best results at MF. The chi-square test showed significant differences between the acceptable measurements at AC and at MF for the Justy II and Novapex (± 0.5 mm) regardless of file adjustment. Under the conditions of the present study, all devices provided acceptable electronic measurements regardless of file adjustment, except for Root ZX which had its performance improved significantly when the precisely fit apical file was used. Justy II and Novapex provided electronic measurements nearest to the AC.

  10. Do Parameters Of Irradiation Influences The Apical Sealing Of Er:YAG Laser Apicetomies?

    Science.gov (United States)

    Marques, Aparecida Maria Cordeiro; dos Santos, Jean Nunes; Pinheiro, Antonio Luiz Barbosa

    2011-08-01

    Failures on the sealing of the tooth apex are responsible for many failures of apical surgeries. The Er:YAG laser has been proposed as an alternative for the use of rotator instruments on surgical endodontics. 12 human extracted canines had root endodontic treatment being the apical limit was set at 1mm before the apical foramen and were distributed into 2 groups. On group I, apicectomy was performed with the Er:YAG laser (250 mJ/15 Hz). Apical cut was performed of perpendicular mode with 3mm from the apical foramen. On Group II, the same procedures and the same sequence as above was used, varying only the parameters of the Er:YAG laser (400 mJ/6 Hz). The specimens were divided into groups and fixed, by the cervical third, on wax. Impermeabilization of the residual root apical third was performed following the same procedures used in the cervical third but the residual apex was left free from the impermeabilization. After that, the roots were immersed in a 2% methylene blue solution and placed in a bacteriological oven for 48 h. The segments were visually observed and the one showing greatest level of dye leakage was selected and kept in individual container and coded accordingly. Apical staining was measured using a stereoscopic magnifying glass; a compass; and caliper. The results showed that Group I showed significantly different higher mean level of dye leakage (5.67±4.9, papicectomies carried out with 400 mJ/6 Hz showed the smallest infiltration value.

  11. Increased proximal bifurcation of CA1 pyramidal apical dendrites in sema3A mutant mice.

    Science.gov (United States)

    Nakamura, Fumio; Ugajin, Kozue; Yamashita, Naoya; Okada, Takako; Uchida, Yutaka; Taniguchi, Masahiko; Ohshima, Toshio; Goshima, Yoshio

    2009-10-10

    Semaphorin-3A (Sema3A) is an attractive guidance molecule for cortical apical dendrites. To elucidate the role of Sema3A in hippocampal dendritic formation, we examined the Sema3A expression pattern in the perinatal hippocampal formation and analyzed hippocampal dendrites of the brains from young adult sema3A mutant mice. Sema3A protein was predominantly expressed in the hippocampal plate and the inner marginal zone at the initial period of apical dendritic growth. Neuropilin-1 and plexin-A, the receptor components for Sema3A, were also localized in the same regions. The Golgi impregnation method revealed that in wildtype mice more than 90% of hippocampal CA1 pyramidal neurons extended a single trunk or apical trunks bifurcated in stratum radiatum. Seven percent of the pyramidal neurons showed proximal bifurcation of apical trunks in stratum pyramidale or at the border of the stratum pyramidale and stratum radiatum. In sema3A mutant mice, proximally bifurcated apical dendrites were increased to 32%, while the single apical dendritic pyramidal neurons were decreased. We designate this phenotype in sema3A mutant mice as "proximal bifurcation." In the dissociated culture system, approximately half of the hippocampal neurons from wildtype mice resembled pyramidal neurons, which possess a long, thick, and tapered dendrite. In contrast, only 30% of the neurons from sema3A mutants exhibited pyramidal-like morphology. Proximal bifurcation of CA1 pyramidal neurons was also increased in the mutant mice of p35, an activator of cyclin-dependent kinase 5 (Cdk5). Thus, Sema3A may facilitate the initial growth of CA1 apical dendrites via the activation of p35/Cdk5, which may in turn signal hippocampal development.

  12. Presynaptic spike broadening reduces junctional potential amplitude.

    Science.gov (United States)

    Spencer, A N; Przysiezniak, J; Acosta-Urquidi, J; Basarsky, T A

    1989-08-24

    Presynaptic modulation of action potential duration may regulate synaptic transmission in both vertebrates and invertebrates. Such synaptic plasticity is brought about by modifications to membrane currents at presynaptic release sites, which, in turn, lead to changes in the concentration of cytosolic calcium available for mediating transmitter release. The 'primitive' neuromuscular junction of the jellyfish Polyorchis penicillatus is a useful model of presynaptic modulation. In this study, we show that the durations of action potentials in the motor neurons of this jellyfish are negatively correlated with the amplitude of excitatory junctional potentials. We present data from in vitro voltage-clamp experiments showing that short duration voltage spikes, which elicit large excitatory junctional potentials in vivo, produce larger and briefer calcium currents than do long duration action potentials, which elicit small excitatory junctional potentials.

  13. Laparoscopically assisted pyeloplasty for ureteropelvic junction ...

    African Journals Online (AJOL)

    junction obstruction: a transperitoneal versus a retroperitoneal approach ... laparoscopic-assisted dismembered pyeloplasty (TLADP) ... to an open technique for two patients of the TLADP group; ... Annals of Pediatric Surgery 2012, 8:29–31.

  14. A self-aligned nano-fabrication process for vertical NbN-MgO-NbN Josephson junctions

    Science.gov (United States)

    Grimm, A.; Jebari, S.; Hazra, D.; Blanchet, F.; Gustavo, F.; Thomassin, J.-L.; Hofheinz, M.

    2017-10-01

    We present a new process for fabricating vertical NbN-MgO-NbN Josephson junctions using self-aligned silicon nitride spacers. It allows for a wide range of junction areas from 0.02 to several 100 μm2. At the same time, it is suited for the implementation of complex microwave circuits with transmission line impedances ranging from 1 {{k}}{{Ω }}. The constituent thin films and the finished junctions are characterized. The latter are shown to have high gap voltages (> 4 {mV}) and low sub-gap leakage currents.

  15. Androgen-Dependent Sertoli Cell Tight Junction Remodeling Is Mediated by Multiple Tight Junction Components

    National Research Council Canada - National Science Library

    Chakraborty, Papia; William Buaas, F; Sharma, Manju; Smith, Benjamin E; Greenlee, Anne R; Eacker, Stephen M; Braun, Robert E

    2014-01-01

    Sertoli cell tight junctions (SCTJs) of the seminiferous epithelium create a specialized microenvironment in the testis to aid differentiation of spermatocytes and spermatids from spermatogonial stem cells...

  16. Junction Plasmon-Induced Molecular Reorientation

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Hu, Dehong; Hess, Wayne P.

    2013-10-17

    Time and frequency dependent intensity variations in sequences of Raman spectra recorded at plasmonic junctions can be assigned to molecular reorientation. This is revealed through Raman trajectories recorded at a nanojunction formed between a silver AFM tip and a corrugated silver surface coated with biphenyl-4,4’-dithiol. Molecular motion is not observed when the tip is retracted and only surface enhancement is operative. In effect, junction plasmon induced molecular reorientation is tracked.

  17. [Clinical anatomy of the esophagogastric junction].

    Science.gov (United States)

    Tănase, M; Aldea, A S

    2012-01-01

    The esophagogastric junction is a controversial anatomical area, due to its sphincteric mechanism which does not show an obvious anatomical basis. The aim of this study is to investigate the anatomical components that endoscopically indicate the mucosal esophagogastric junction in hiatal hernia patients. The esophagogastric junction was investigated in 27 hiatal hernia patients undergoing surgery. Hiatal hernia is an extension of the stomach situated between the esophagogastric junction and the diaphragmatic indentation. The following types of hiatal hernia were found: sliding hiatal hernia (type I) in 4 patients (14.81%), rolling hiatal hernia (type II) in 2 (7.4%), mixed hiatal hernia (type III) in 12 (44.44%), type IV hiatal hernia in 4 (14.81%) and recurrent hiatal hernia in 5 (18.51%). Of the 27 hiatal hernia patients, 8 (29.6%) were operated using classical procedures: laparotomy--6 (75%) and laparoscopic surgery--2 (25%). The angle of His cannot be used for marking the mucosal esophagogastric junction due to the severe damage of the lower esophageal sphincter in hiatal hernia patients. The squamocolumnar junction is displaced in hiatal hernia patients and was not an option for the study group. The distal end of the esophageal longitudinal palisading vessels needs medication (proton pump inhibitors that reduce the gastric acid production), in order to enhance the visibility of these vessels. The proximal end of gastric longitudinal mucosal folds proved to be the most reliable site to identify endoscopically the mucosal esophagogastric junction. The anatomical structure of the esophagogastric junction differs in hiatal hernia patients and these peculiarities are very important in surgery.

  18. 144例显微根尖外科手术疗效观察及分析%Outcome evaluation of 144 cases of apical microsurgery

    Institute of Scientific and Technical Information of China (English)

    邹进; 汪小彤; 刘卫红; 张光东; 王娟; 石炜

    2016-01-01

    Objective To evaluate the success rate and potential prognostic factors of apical microsurgery and provide references for treating complex periapical diseases which cannot be cured through root canal therapy. Method 144 patients who received apical mi-crosurgery from 2012 to 2014 in our hospital were followed up for one year, 190 teeth in total. Therapeutic effect of apical microsurgery was evaluated by improvement in symptoms, clinical examination and radiographical examination. Statistical analysis was used to ana-lyze the prognostic factors of gender, age, and tooth position. Results The one year success rate was 92. 63% (176 teeth) and the failure rate is 7. 37% (14 teeth). Gender, age and tooth location had no significant influences on the outcome of apical microsurgery. Conclusion Apical microsurgery provides an effective method for treating complex periapical diseases, and is worthy of being applied in clinic.%目的:通过对显微根尖手术后患者临床随访评估,探讨显微根尖手术的成功率以及相关预后影响因素,为无法行根管治疗的复杂根尖周病的治疗提供参考。方法对2012—2014年底在我院行显微根尖手术的144例患者进行1年随访,收集患者主观症状、临床检查以及拍摄根尖X线片相关资料,综合评估显微根尖手术疗效,并统计分析性别、年龄及牙位预后影响因素。结果对144例患者共190颗患牙相关资料进行分析,1年有效率达92.63%(176颗),无效率为7.37%(14颗)。统计学分析结果显示患者的性别、年龄及牙位分布对显微根尖外科手术的预后无明显影响。结论显微根尖外科手术可以有效治疗复杂根尖周病变的有效方法,值得临床推广。

  19. Fibroblast growth factor signaling potentiates VE-cadherin stability at adherens junctions by regulating SHP2.

    Directory of Open Access Journals (Sweden)

    Kunihiko Hatanaka

    Full Text Available BACKGROUND: The fibroblast growth factor (FGF system plays a critical role in the maintenance of vascular integrity via enhancing the stability of VE-cadherin at adherens junctions. However, the precise molecular mechanism is not well understood. In the present study, we aimed to investigate the detailed mechanism of FGF regulation of VE-cadherin function that leads to endothelial junction stabilization. METHODS AND FINDINGS: In vitro studies demonstrated that the loss of FGF signaling disrupts the VE-cadherin-catenin complex at adherens junctions by increasing tyrosine phosphorylation levels of VE-cadherin. Among protein tyrosine phosphatases (PTPs known to be involved in the maintenance of the VE-cadherin complex, suppression of FGF signaling reduces SHP2 expression levels and SHP2/VE-cadherin interaction due to accelerated SHP2 protein degradation. Increased endothelial permeability caused by FGF signaling inhibition was rescued by SHP2 overexpression, indicating the critical role of SHP2 in the maintenance of endothelial junction integrity. CONCLUSIONS: These results identify FGF-dependent maintenance of SHP2 as an important new mechanism controlling the extent of VE-cadherin tyrosine phosphorylation, thereby regulating its presence in adherens junctions and endothelial permeability.

  20. Gap junction intercellular communication and benzene toxicity.

    Science.gov (United States)

    Rivedal, Edgar; Witz, Gisela; Leithe, Edward

    2010-03-19

    Aberrant regulation of gap junction intercellular communication (GJIC) has been linked to several human diseases, including cancer and abnormal hematopoietic development. Benzene exposure has been shown to cause hematotoxicity and leukemia, but the underlying mechanisms involved remain unclear. We have observed that several metabolites of benzene have the ability to block gap junction intercellular communication. The ring-opened trans,trans-muconaldehyde (MUC) was found to be the most potent inhibitor of gap junction channels. MUC was found to induce cross-linking of the gap junction protein connexin43, which seemed to be responsible for the induced inhibition of GJIC. Glutaraldehyde, which has a similar molecular structure as MUC, was found to possess similar effects on gap junctions as MUC, while the mono-aldehyde formaldehyde shows lower potency, both as a connexin cross-linker, and as an inhibitor of GJIC. Both glutaraldehyde and formaldehyde have previously been associated with induction of leukemia and disturbance of hematopoiesis. Taken together, the data support a possible link between the effect of MUC on gap junctions, and the toxic effects of benzene. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  1. Gap junctions: structure and function (Review).

    Science.gov (United States)

    Evans, W Howard; Martin, Patricia E M

    2002-01-01

    Gap junctions are plasma membrane spatial microdomains constructed of assemblies of channel proteins called connexins in vertebrates and innexins in invertebrates. The channels provide direct intercellular communication pathways allowing rapid exchange of ions and metabolites up to approximately 1 kD in size. Approximately 20 connexins are identified in the human or mouse genome, and orthologues are increasingly characterized in other vertebrates. Most cell types express multiple connexin isoforms, making likely the construction of a spectrum of heteromeric hemichannels and heterotypic gap junctions that could provide a structural basis for the charge and size selectivity of these intercellular channels. The precise nature of the potential signalling information traversing junctions in physiologically defined situations remains elusive, but extensive progress has been made in elucidating how connexins are assembled into gap junctions. Also, participation of gap junction hemichannels in the propagation of calcium waves via an extracellular purinergic pathway is emerging. Connexin mutations have been identified in a number of genetically inherited channel communication-opathies. These are detected in connexin 32 in Charcot Marie Tooth-X linked disease, in connexins 26 and 30 in deafness and skin diseases, and in connexins 46 and 50 in hereditary cataracts. Biochemical approaches indicate that many of the mutated connexins are mistargeted to gap junctions and/or fail to oligomerize correctly into hemichannels. Genetic ablation approaches are helping to map out a connexin code and point to specific connexins being required for cell growth and differentiation as well as underwriting basic intercellular communication.

  2. Predictive modelling of ferroelectric tunnel junctions

    Science.gov (United States)

    Velev, Julian P.; Burton, John D.; Zhuravlev, Mikhail Ye; Tsymbal, Evgeny Y.

    2016-05-01

    Ferroelectric tunnel junctions combine the phenomena of quantum-mechanical tunnelling and switchable spontaneous polarisation of a nanometre-thick ferroelectric film into novel device functionality. Switching the ferroelectric barrier polarisation direction produces a sizable change in resistance of the junction—a phenomenon known as the tunnelling electroresistance effect. From a fundamental perspective, ferroelectric tunnel junctions and their version with ferromagnetic electrodes, i.e., multiferroic tunnel junctions, are testbeds for studying the underlying mechanisms of tunnelling electroresistance as well as the interplay between electric and magnetic degrees of freedom and their effect on transport. From a practical perspective, ferroelectric tunnel junctions hold promise for disruptive device applications. In a very short time, they have traversed the path from basic model predictions to prototypes for novel non-volatile ferroelectric random access memories with non-destructive readout. This remarkable progress is to a large extent driven by a productive cycle of predictive modelling and innovative experimental effort. In this review article, we outline the development of the ferroelectric tunnel junction concept and the role of theoretical modelling in guiding experimental work. We discuss a wide range of physical phenomena that control the functional properties of ferroelectric tunnel junctions and summarise the state-of-the-art achievements in the field.

  3. Peanut Allergens Alter Intestinal Barrier Permeability and Tight Junction Localisation in Caco-2 Cell Cultures1

    Directory of Open Access Journals (Sweden)

    Dwan B. Price

    2014-05-01

    Full Text Available Background/Aims: Allergen absorption by epithelia may play an important role in downstream immune responses. Transport mechanisms that can bypass Peyer's patches include transcellular and paracellular transport. The capacity of an allergen to cross via these means can modulate downstream processing of the allergen by the immune system. The aim of this study was to investigate allergen-epithelial interactions of peanut allergens with the human intestinal epithelium. Methods: We achieved this using the human Caco-2 cell culture model, exposed to crude peanut extract. Western and immunofluorescence analysis were used to identify the cellular and molecular changes of peanut extract on the intestinal epithelium. Results: Following exposure of Caco-2 cells to peanut extract, binding of the peanut allergens Ara h 1 and Ara h 2 to the apical cellular membrane and transcytosis across the monolayers were observed. Additionally, the co-localisation of the transmembrane tight junction proteins occludin, JAM-A and claudin-1, with the intracellular adhesion protein ZO-1 was modified. Conclusion: Disruption of Caco-2 barrier integrity through tight junction disruption may enable movement of peanut proteins across the intestinal epithelium. This accounts for peanut's increased allergenicity, compared to other food allergens, and provides an explanation for the potency of peanut allergens in immune response elicitation.

  4. Claudin Loss-of-Function Disrupts Tight Junctions and Impairs Amelogenesis

    Directory of Open Access Journals (Sweden)

    Claire Bardet

    2017-05-01

    Full Text Available Claudins are a family of proteins that forms paracellular barriers and pores determining tight junctions (TJ permeability. Claudin-16 and -19 are pore forming TJ proteins allowing calcium and magnesium reabsorption in the thick ascending limb of Henle's loop (TAL. Loss-of-function mutations in the encoding genes, initially identified to cause Familial Hypomagnesemia with Hypercalciuria and Nephrocalcinosis (FHHNC, were recently shown to be also involved in Amelogenesis Imperfecta (AI. In addition, both claudins were expressed in the murine tooth germ and Claudin-16 knockout (KO mice displayed abnormal enamel formation. Claudin-3, an ubiquitous claudin expressed in epithelia including kidney, acts as a barrier-forming tight junction protein. We determined that, similarly to claudin-16 and claudin-19, claudin-3 was expressed in the tooth germ, more precisely in the TJ located at the apical end of secretory ameloblasts. The observation of Claudin-3 KO teeth revealed enamel defects associated to impaired TJ structure at the secretory ends of ameloblasts and accumulation of matrix proteins in the forming enamel. Thus, claudin-3 protein loss-of-function disturbs amelogenesis similarly to claudin-16 loss-of-function, highlighting the importance of claudin proteins for the TJ structure. These findings unravel that loss-of-function of either pore or barrier-forming TJ proteins leads to enamel defects. Hence, the major structural function of claudin proteins appears essential for amelogenesis.

  5. The potassium impermeable apical membrane of insect epithelia: a target for development of safe pesticides

    Directory of Open Access Journals (Sweden)

    William R. Harvey

    1987-01-01

    Full Text Available Columnar cell apical membranes (CCAM in series with goblet cell apical membranes (GCAM form an electroosmotic barrier separating the midgut lumen from epithelial cell cytoplasm. A unique K+ ATPase in GCAM generates three gradients across this barrier. A greater than 180 mV electrical gradient (lumen positive drives amino acid uptake through voltage-dependent K+ symports. A greater than 1000-fold [H+] gradient (lumen alkaline and a greater than 10-fold [K+] gradient (lumen concentrated are adaptations to the high tannin and high K+ content, respectively, in dietary plant material. Agents which act on the apical membrane and disrupt the PD, H+, or K+ gradients are potential insecticides. Insect sensory epithelia and mammalian stria vascularis maintain similar PD and K+ gradients but would not be exposed to ingested anti-apical membrane insecticides. Following the demonstration by Sacchi et al. that Bacillus thuringiensis delta-endotoxin (Bt induces specifically a K+ conductance increase in CCAM vesicles, we find that the K+ channel blocking agent, Ba2+, completely reverses Bt inhibition of the K+-carried short circuit current in the isolated midgut of Manduca sexta. Progress in characterizing the apical membrane includes finding that fluorosulfonylbenzoyladenosine binds specifically to certain GCAM polypeptides and that CCAM vesicles can be mass produced by Ca2+ or Mg2+ precipitation from Manduca sexta midgut.

  6. Midventricular Hypertrophic Cardiomyopathy with Apical Aneurysm: Potential for Underdiagnosis and Value of Multimodality Imaging

    Directory of Open Access Journals (Sweden)

    Archana Sivanandam

    2016-01-01

    Full Text Available We illustrate a case of midventricle obstructive HCM and apical aneurysm diagnosed with appropriate use of multimodality imaging. A 75-year-old African American woman presented with a 3-day history of chest pain and dyspnea with elevated troponins. Her electrocardiogram showed sinus rhythm, left atrial enlargement, left ventricular hypertrophy, prolonged QT, and occasional ectopy. After medical therapy optimization, she underwent coronary angiography for an initial diagnosis of non-ST segment elevation myocardial infarction. Her coronaries were unremarkable for significant disease but her left ventriculogram showed hyperdynamic contractility of the midportion of the ventricle along with a large dyskinetic aneurysmal apical sac. A subsequent transthoracic echocardiogram provided poor visualization of the apical region of the ventricle but contrast enhancement identified an aneurysmal pouch distal to the midventricular obstruction. To further clarify the diagnosis, cardiac magnetic resonance imaging with contrast was performed confirming the diagnosis of midventricular hypertrophic cardiomyopathy with apical aneurysm and fibrosis consistent with apical scar on delayed enhancement. The patient was medically treated and subsequently underwent elective implantable defibrillator placement in the ensuing months for recurrent nonsustained ventricular tachycardia and was initiated on prophylactic oral anticoagulation with warfarin for thromboembolic risk reduction.

  7. The sealing ability of MTA apical plugs exposed to a phosphate-buffered saline.

    Science.gov (United States)

    Almeida, Josiane de; Alves, Ana Maria Hecke; Melo, Roberto Ferreira de; Felippe, Mara Cristina Santos; Bortoluzzi, Eduardo Antunes; Teixeira, Cleonice da Silveira; Felippe, Wilson Tadeu

    2013-01-01

    The aim of this study was to evaluate the influence of exposure of the mineral trioxide aggregate (MTA) - with and without calcium chloride (CaCl2) - to phosphate-buffered saline (PBS) on the apical microleakage using a glucose leakage system. Sixty root segments were randomly divided into 4 experimental groups (n=15). After resecting the apical segments and enlarging the canals with Gates-Glidden drills, the apical cavities were filled with MTA with or without CaCl2 and the root canals were dressed with a moistened cotton pellet or PBS, as follows: 1) MTA/cotton pellet; 2) MTA/PBS; 3) MTA+10%CaCl2/cotton pellet; 4) MTA+10%CaCl2/PBS. All root segments were introduced in floral foams moistened with PBS. After 2 months, all root segments were prepared to evaluate the glucose leakage along the apical plugs. The amount of glucose leakage was measured following an enzymatic reaction and quantified by a spectrophotometer. Four roots were used as controls. The data were analyzed using Kruskal-Wallis and Mann-Whitney tests (p0.05), and 3 and 4 (p>0.05). The addition of CaCl2 to the MTA significantly decreased its sealing ability (pMTA sealing ability. The addition of CaCl2 to the MTA negatively influenced the apical seal.

  8. The Effect of Smear Layer on Apical Seal of Endodontically Treated Teeth

    Directory of Open Access Journals (Sweden)

    A Farhad

    2004-06-01

    Full Text Available Background: The purpose of this study was to evaluate the effect of smear layer on apical seal of endodontically treated teeth. Methods: Sixty extracted single–rooted human teeth were randomly divided into two experimental groups (n=25 and two control groups (n=5. The teeth were instrumented with K–type files to size 40 and then flared. Apical patency was ensured in all teeth. 5% sodium hypochlorite and 17% Ethylenediamine tetraacetic acid was used as irrigants to remove the smear layer in the second experimental group. The experimental groups were obturated by laterally condensed gutta – percha with Roth 801 sealer. The positive control group was obturated with gutta – percha without sealer. The root surfaces were then coated with nail polish and sticky wax except for the apex in the experimental groups and positive control group. The roots were completely covered in the negative control group. The samples were then immersed in India ink for 1 week at 37°C. Results: The statistical analysis of the results showed that the apical leakage was significantly increased in obturated canals with smear layer. Conclusion: The removal of smear layer might improve the long term apical seal and success of endodontically treated teeth. Keywords: Apical Seal, EDTA, Removal, Sodium Hypochlorite, Smear Layer.

  9. Local auxin sources orient the apical-basal axis in Arabidopsis embryos.

    Science.gov (United States)

    Robert, Hélène S; Grones, Peter; Stepanova, Anna N; Robles, Linda M; Lokerse, Annemarie S; Alonso, Jose M; Weijers, Dolf; Friml, Jiří

    2013-12-16

    Establishment of the embryonic axis foreshadows the main body axis of adults both in plants and in animals, but underlying mechanisms are considered distinct. Plants utilize directional, cell-to-cell transport of the growth hormone auxin to generate an asymmetric auxin response that specifies the embryonic apical-basal axis. The auxin flow directionality depends on the polarized subcellular localization of PIN-FORMED (PIN) auxin transporters. It remains unknown which mechanisms and spatial cues guide cell polarization and axis orientation in early embryos. Herein, we provide conceptually novel insights into the formation of embryonic axis in Arabidopsis by identifying a crucial role of localized tryptophan-dependent auxin biosynthesis. Local auxin production at the base of young embryos and the accompanying PIN7-mediated auxin flow toward the proembryo are required for the apical auxin response maximum and the specification of apical embryonic structures. Later in embryogenesis, the precisely timed onset of localized apical auxin biosynthesis mediates PIN1 polarization, basal auxin response maximum, and specification of the root pole. Thus, the tight spatiotemporal control of distinct local auxin sources provides a necessary, non-cell-autonomous trigger for the coordinated cell polarization and subsequent apical-basal axis orientation during embryogenesis and, presumably, also for other polarization events during postembryonic plant life.

  10. In vitro evaluation of Root ZX and Raypex 6 in teeth with different apical diameters

    Directory of Open Access Journals (Sweden)

    Ugur Aydin

    2015-01-01

    Full Text Available Background: There is a growing interest about electronic apex locators for working length determination. There are several studies dealing with their performance in different conditions. Aims: The aim of this study is to evaluate the accuracy of Root ZX and Raypex 6 in teeth with different apical diameters. Materials and Methods: Actual working length (AWL of 80 single rooted teeth were determined as 0.5 mm short of apical foramen. The teeth were divided into 4 groups (n = 20. First group (G 0 included teeth with mature apices. Root canals of the other groups (G 32, G 57 and G 72 were enlarged until apical sizes of 0.32, 0.57 and 0.72 mm were obtained. Samples were embedded in alginate and electronic measurements (EM were performed. Statistical analysis: was achieved with Fisher exact test. Results: Both devices revealed a high rate of success in G 0 and G 32. Their accuracy decreased significantly in G 57 and G 72 groups (P 0.05. Conclusions: Root ZX and Raypex 6 are reliable in teeth with mature apices. At foramen diameters exceeding 0.57 mm, their accuracy is susceptible.

  11. Revitalization of open apex teeth with apical periodontitis using a collagen-hydroxyapatite scaffold.

    Science.gov (United States)

    Nevins, Alan J; Cymerman, Jerome J

    2015-06-01

    An enhanced revision of the revitalization endodontic technique for immature teeth with apical periodontitis has been described. It includes the addition of collagen-hydroxyapatite scaffold to the currently practiced revascularization technique. Four cases treated in series are presented in this report, 1 case involving 2 teeth. Periapical diagnoses of immature teeth included "asymptomatic apical periodontitis," "symptomatic apical periodontitis," and "acute apical abscess." Additionally, 1 fully developed tooth that had undergone root canal treatment that failed had a periapical diagnosis of acute apical abscess. An established revascularization protocol was used for all teeth. In addition to stimulating blood clots, all teeth were filled with collagen-hydroxyapatite scaffolds. Periapical radiolucencies healed in all teeth, and diffuse radiopacity developed within the coronal portions of canal spaces. Root development with root lengthening occurred in the immature nonvital maxillary premolar that had not undergone prior treatment. The technique of adding a collagen-hydroxyapatite scaffold to the existing revitalization protocol has been described in which substantial hard tissue repair has occurred. This may leave teeth more fully developed and less likely to fracture.

  12. Effects of apical meristem loss on sylleptic branching and growth of hybrid poplar

    Energy Technology Data Exchange (ETDEWEB)

    Zeleznik, Joseph D. [North Dakota State University, Fargo, ND (United States). Plant Sciences Department

    2007-07-15

    The effects of apical meristem loss on the growth and development of hybrid poplar trees was investigated. This was done by clipping back either the apical meristem alone (dividing cells), or the apical meristem plus a small amount of additional stem tissue (expanding cells, <1 cm), at various times during the first growing season. Two clones (NM6-nonsylleptic habit, and DN34-slightly sylleptic habit) were tested at close spacing (0.6 m) in the nursery. Clipping generally increased the number of sylleptic branches formed. Clipping 69 days after planting resulted in the largest number of sylleptic branches while clipping 4 weeks later gave no increase in syllepsis. Clipping temporarily reduced height growth of both clones but total height at the end of the first growing season was not affected by any treatment. There were some slight differences in growth during the second growing season; despite these differences, total stem biomass and total tree biomass after 2 years were not affected by temporary loss of the apical meristem in the first growing season. Results suggest that death or removal of hybrid poplar apical meristems by tip borers or ungulates has no long-term effects on aboveground growth as measured by height or biomass. (author)

  13. Speckle tracking echocardiography to assess regional ventricular function in patients with apical hypertrophic cardiomyopathy

    Science.gov (United States)

    Saccheri, María Cristina; Cianciulli, Tomás Francisco; Morita, Luis Alberto; Méndez, Ricardo José; Beck, Martín Alejandro; Guerra, Juan Enrique; Cozzarin, Alberto; Puente, Luciana Jimena; Balletti, Lorena Romina; Lax, Jorge Alberto

    2017-01-01

    AIM To explore regional systolic strain of midwall and endocardial segments using speckle tracking echocardiography in patients with apical hypertrophic cardiomyopathy (HCM). METHODS We prospectively assessed 20 patients (mean age 53 ± 16 years, range: 18-81 years, 10 were male), with apical HCM. We measured global longitudinal peak systolic strain (GLPSS) in the midwall and endocardium of the left ventricle. RESULTS The diastolic thickness of the 4 apical segments was 16.25 ± 2.75 mm. All patients had a normal global systolic function with a fractional shortening of 50% ± 8%. In spite of supernormal left ventricular (LV) systolic function, midwall GLPSS was decreased in all patients, more in the apical (-7.3% ± -8.8%) than in basal segments (-15.5% ± -6.93%), while endocardial GLPPS was significantly greater and reached normal values (apical: -22.8% ± -7.8%, basal: -17.9% ± -7.5%). CONCLUSION This study shows that two-dimensional strain was decreased mainly confined to the mesocardium, while endocardium myocardial deformation was preserved in HCM and allowed to identify subclinical LV dysfunction. This transmural heterogeneity in systolic strain had not been previously described in HCM and could be explained by the distribution of myofibrillar disarray in deep myocardial areas. The clinical application of this novel finding may help further understanding of the pathophysiology of HCM. PMID:28515855

  14. Cholinergic modulation differs between basal and apical dendritic excitation of hippocampal CA1 pyramidal cells.

    Science.gov (United States)

    Leung, L Stan; Péloquin, Pascal

    2010-08-01

    We hypothesize that endogenous cholinergic modulation of dendritic processing of hippocampal CA1 is layer specific, and it specifically enhances spike output resulting from basal as compared with the apical dendritic excitation. Laminar profiles of evoked field potentials were recorded in the CA1 area of urethane-anesthetized rats using multichannel silicon probes and analyzed as current source density. High-frequency stimulation of the pontis oralis (PnO) attenuated the midapical more than the basal or distal apical dendritic excitatory sink. Population spike (PS) and excitatory sink-PS potentiation resulting from basal dendritic excitation were facilitated, while the PS evoked by apical dendritic stimulation was attenuated by PnO stimulation. Perfusion of cholinergic agonist carbachol onto hippocampal slices in vitro also attenuated the apical more than the basal dendritic excitatory postsynaptic potentials. Excitatory sink attenuation and PS changes after PnO stimulation were blocked by systemic or local scopolamine and by intracerebroventricular (icv) M1 receptor antagonist pirenzepine but not by icv M2 receptor antagonist AFDX-116 or nicotinic antagonists. However, a hippocampal theta rhythm activated by PnO stimulation was blocked by systemic but not by local scopolamine. We conclude that endogenous acetylcholine mediates a stronger presynaptic inhibition of the midapical than basal and distal apical excitation mainly through M1 receptors.

  15. Reguladores vegetais na quebra da dominância apical de mamoeiro (Carica papaya L. Plant growth regulators on breaking apical dominance in papaya plants (Carica papaya L.

    Directory of Open Access Journals (Sweden)

    Elizabeth Orika Ono

    2004-08-01

    Full Text Available O trabalho avaliou os efeitos de reguladores vegetais sobre a quebra da dominância apical de mamoeiro (Carica papaya L. cv. Improved Sunrise Solo. A aplicação dos reguladores vegetais foi iniciada quando as plantas tinham seis meses de idade, totalizando três aplicações, a intervalos de sete dias, constando dos seguintes tratamentos: T1- água (testemunha; T2- GA3 250 mg L-1; T3- GA3 500 mg L-1; T4- benziladenina (BA 250 mg L-1; T5- BA 500 mg L-1; T6- GA3 125 mg L-1 + BA 125 mg L-1; T7- GA3 250 mg L-1 + BA 250 mg L-1. Esses tratamentos foram acompanhados da remoção ou não da gema apical. Os resultados mostraram que plantas tratadas com GA3 + BA a 125 e 250 mg L-1, com e sem a remoção da gema apical, apresentaram maior número de brotações que a testemunha, a qual não apresentou nenhuma brotação das gemas laterais.The objective of this work was to study the effects of gibberelin and cytokinin on breaking apical dominance and axillary buds growth of the Carica papaya L. Papaya plants sprayed three times within a period of 7 days, with the following treatments: T1- water (control, T2- GA3 250 mg L-1, T3- GA3 500 mg L-1, T4- benzyladenine (BA 250 mg L-1, T5- BA 500 mg L-1, T6- GA3 125 mg L-1 + BA 125 mg L-1, T7- GA3 250 mg L-1 + BA 250 mg L-1. The treatments were carried out with or without removal of the apical buds. After 36 days of the last plant growth regulators application was observed lateral bud numbers, lateral buds length and lateral buds diameter. The results showed that there were a higher number of shoots in plants treated with GA3 at 125 mg L-1 + BA at 125 mg L-1 and GA3 at 250mg L-1 + BA at 250 mg L-1. The removal of the apical bud helped the sprouting of the papaya plants.

  16. Numerical study of junction-angle effects on flow pattern in a river ...

    African Journals Online (AJOL)

    2016-01-01

    Jan 1, 2016 ... This complexity is not only because of their turbulence and intense ... The use of numerical models for simulating the flow in river junctions has ..... longitudinal velocity profiles in different sections of the main channel is shown ...

  17. Modeling superconducting networks containing Josephson junctions by means of PC-based circuit simulation software

    Energy Technology Data Exchange (ETDEWEB)

    Blackburn, J.A. (Department of Physics and Computing, Wilfrid Laurier University, Waterloo, ON (Canada)); Smith, H.J.T. (Department of Physics, University of Waterloo, Waterloo, ON (Canada))

    1990-09-01

    Software packages are now available with which complex analog electronic circuits can be simulated on desktop computers. Using Micro Cap III it is demonstrated that the modeling capabilities of such software can be extended to include {ital superconducting} networks by means of an appropriate equivalent circuit for a Josephson junction.

  18. Regulation of Tight Junction Permeability by Intestinal Bacteria and Dietary Components

    NARCIS (Netherlands)

    Ulluwishewa, D.; Anderson, R.C.; McNabb, W.C.; Moughan, P.J.; Wells, J.; Roy, N.C.

    2011-01-01

    The human intestinal epithelium is formed by a single layer of epithelial cells that separates the intestinal lumen from the underlying lamina propria. The space between these cells is sealed by tight junctions (TJ), which regulate the permeability of the intestinal barrier. TJ are complex protein s

  19. Regulation of Tight Junction Permeability by Intestinal Bacteria and Dietary Components

    NARCIS (Netherlands)

    Ulluwishewa, D.; Anderson, R.C.; McNabb, W.C.; Moughan, P.J.; Wells, J.; Roy, N.C.

    2011-01-01

    The human intestinal epithelium is formed by a single layer of epithelial cells that separates the intestinal lumen from the underlying lamina propria. The space between these cells is sealed by tight junctions (TJ), which regulate the permeability of the intestinal barrier. TJ are complex protein

  20. Dissection of the functional domains of an archaeal holliday junction helicase

    DEFF Research Database (Denmark)

    Hong, Ye; Chu, Mingzhu; Li, Yansheng

    2012-01-01

    Helicases and nucleases form complexes that play very important roles in DNA repair pathways some of which interact with each other at Holliday junctions. In this study, we present in vitro and in vivo analysis of Hjm and its interaction with Hjc in Sulfolobus. In vitro studies employed Hjm from ...

  1. Cell size and growth regulation in the Arabidopsis thaliana apical stem cell niche

    Science.gov (United States)

    Willis, Lisa; Refahi, Yassin; Wightman, Raymond; Landrein, Benoit; Teles, José; Huang, Kerwyn Casey; Meyerowitz, Elliot M.

    2016-01-01

    Cell size and growth kinetics are fundamental cellular properties with important physiological implications. Classical studies on yeast, and recently on bacteria, have identified rules for cell size regulation in single cells, but in the more complex environment of multicellular tissues, data have been lacking. In this study, to characterize cell size and growth regulation in a multicellular context, we developed a 4D imaging pipeline and applied it to track and quantify epidermal cells over 3–4 d in Arabidopsis thaliana shoot apical meristems. We found that a cell size checkpoint is not the trigger for G2/M or cytokinesis, refuting the unexamined assumption that meristematic cells trigger cell cycle phases upon reaching a critical size. Our data also rule out models in which cells undergo G2/M at a fixed time after birth, or by adding a critical size increment between G2/M transitions. Rather, cell size regulation was intermediate between the critical size and critical increment paradigms, meaning that cell size fluctuations decay by ∼75% in one generation compared with 100% (critical size) and 50% (critical increment). Notably, this behavior was independent of local cell–cell contact topologies and of position within the tissue. Cells grew exponentially throughout the first >80% of the cell cycle, but following an asymmetrical division, the small daughter grew at a faster exponential rate than the large daughter, an observation that potentially challenges present models of growth regulation. These growth and division behaviors place strong constraints on quantitative mechanistic descriptions of the cell cycle and growth control. PMID:27930326

  2. Tissue reaction to Endométhasone sealer in root canal fillings short of or beyond the apical foramen

    Directory of Open Access Journals (Sweden)

    Patrícia Suzuki

    2011-10-01

    Full Text Available OBJECTIVE: This study evaluated the response of periapical tissues to the endodontic sealer Endométhasone in root canal fillings short of or beyond the apical foramen. MATERIAL AND METHODS: Twenty root canals of premolars and incisors of 2 mongrel dogs were used. After coronal access and pulp extirpation, the canals were instrumented up to a size 55 K-file and the apical cemental barrier was penetrated with a size 15 K-file to obtain a main apical foramen, which was widened to a size 25 K-file. The canals were irrigated with saline at each change of file. The root canals were obturated either short of or beyond the apical foramen by the lateral condensation of gutta-percha and Endométhasone, originating 2 experimental groups: G1: Endométhasone/short of the apical foramen; G2: Endométhasone/beyond the apical foramen. The animals were killed by anesthetic overdose 90 days after endodontic treatment. The individual roots were obtained and serial histological sections were prepared for histomorphological analysis (H&E and Brown & Brenn techniques under light microscopy. The following parameters were examined: closure of the apical foramen of the main root canal and apical opening of accessory canals, apical cementum resorption, intensity of the inflammatory infiltrate, presence of giant cells and thickness and organization of the apical periodontal ligament. Each parameter was scored 1 to 4, 1 being the best result and 4 the worst. Data were analyzed statistically by the Wilcoxon nonparametric tests (p=0.05. RESULTS: Comparing the 2 groups, the best result (p<0.05 was obtained with root canal filling with Endométhasone short of the apical foramen but a chronic inflammatory infiltrate was present in all specimens. CONCLUSIONS: Limiting the filling material to the root canal space apically is important to determine the best treatment outcome when Endométhasone is used as sealer.

  3. Estudio sobre la adaptación apical de conos maestros de gutapercha en conductos radiculares instrumentados con limas Lightspeed

    OpenAIRE

    Pumarola Suñé, José; García Campaña, Ana M.; Brau Aguadé, Esteban; Canalda Sahli, Carlos

    2000-01-01

    El objetivo de este trabajo fue establecer la coincidencia entre el calibre del cono maestro apical y la lima maestra apical, así como medir cualitativamente la adaptación de diferentes marcas de conos de gutapercha en el tercio apical de conductos radiculares instrumentados con limas Lightspeed. Se instrumentaron 100 conductos de molares naturales extraídos con el sistema Lightspeed. Las muestras se distribuyeron aleatoriamente en cinco grupos. Cada grupo fue obturado mediante condensación l...

  4. Charge transport in nanoscale junctions.

    Science.gov (United States)

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-03

    many particle excitations, new surface states in semiconductor electrodes, various mechanisms for single molecule rectification of the current, inelastic electron spectra and SERS spectroscopy. Three terminal architectures allowing (electrochemical) gating and transistor effects. Electrochemical nanojunctions and gating: intermolecular electron transfer in multi-redox metalloproteins, contact force modulation, characteristic current-noise patterns due to conformational fluctuations, resonance effects and electrocatalysis. Novel architectures: linear coupled quantum-dot-bridged junctions, electrochemical redox mediated transfer in two center systems leading to double maxima current-voltage plots and negative differential resistance, molecular-nanoparticle hybrid junctions and unexpected mesoscopic effects in polymeric wires. Device integration: techniques for creating stable metal/molecule/metal junctions using 'nano-alligator clips' and integration with 'traditional' silicon-based technology. The Guest Editors would like to thank all of the authors and referees of this special issue for their meticulous work in making each paper a valuable contribution to this research area, the early-bird authors for their patience, and Journal of Physics: Condensed Matter editorial staff in Bristol for their continuous support.

  5. A dynamic genetic-hormonal regulatory network model explains multiple cellular behaviors of the root apical meristem of Arabidopsis thaliana.

    Science.gov (United States)

    García-Gómez, Mónica L; Azpeitia, Eugenio; Álvarez-Buylla, Elena R

    2017-04-01

    The study of the concerted action of hormones and transcription factors is fundamental to understand cell differentiation and pattern formation during organ development. The root apical meristem of Arabidopsis thaliana is a useful model to address this. It has a stem cell niche near its tip conformed of a quiescent organizer and stem or initial cells around it, then a proliferation domain followed by a transition domain, where cells diminish division rate before transiting to the elongation zone; here, cells grow anisotropically prior to their final differentiation towards the plant base. A minimal model of the gene regulatory network that underlies cell-fate specification and patterning at the root stem cell niche was proposed before. In this study, we update and couple such network with both the auxin and cytokinin hormone signaling pathways to address how they collectively give rise to attractors that correspond to the genetic and hormonal activity profiles that are characteristic of different cell types along A. thaliana root apical meristem. We used a Boolean model of the genetic-hormonal regulatory network to integrate known and predicted regulatory interactions into alternative models. Our analyses show that, after adding some putative missing interactions, the model includes the necessary and sufficient components and regulatory interactions to recover attractors characteristic of the root cell types, including the auxin and cytokinin activity profiles that correlate with different cellular behaviors along the root apical meristem. Furthermore, the model predicts the existence of activity configurations that could correspond to the transition domain. The model also provides a possible explanation for apparently paradoxical cellular behaviors in the root meristem. For example, how auxin may induce and at the same time inhibit WOX5 expression. According to the model proposed here the hormonal regulation of WOX5 might depend on the cell type. Our results

  6. Gibberellin Is Involved in the Regulation of Cell Death-mediated Apical Senescence in G2 Pea

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Senescence is the process of programmed degradation.The G2 line of pea exhibits apical senescence-delaying phenotype under short-day(SD)conditions,but the mechanism regulating the apical senescence is still largely unknown.Gibberellin (GA)was proved to be able to delay this apical senescence phenotype in G2 pea grown under long-day(LD) conditions.Here we show that the initiation of cell death signals in the tarminal floral meristem was involved in the regulation of apical senescence in pea plants.SD signals prevented the formation of the cell death region in the apical mersitem.Moreovsr.GA3 treatment could effectively inhibit the occurrence of cell death-mediated apical senescence in LD-grown apical buds.Therefore,our data suggest that the prevention of apical senescence in SD-grown G2 pea through GA3 treatment may be largely responsible for the regulation of occurrence of the DNA fragmentation in apical meristem.

  7. Craniocervical junction diseases treatment with a minimally invasive approach

    Directory of Open Access Journals (Sweden)

    Roberto Carlos Díaz

    2014-01-01

    Full Text Available Objective: To introduce a new minimally invasive surgical approach to anterior and lateral craniocervical junction diseases, preserving the midline posterior cervical spine stabilizing elements and reducing the inherent morbidity risk associated with traditional approaches. Methods: We describe a novel surgical technique in four cases of extra-medullary anterolateral compressive lesions located in the occipito-cervical junction, including infections and intra- and/or extradural tumor lesions. We used a paramedian trasmuscular approach through an anatomical muscle corridor using a micro MaXcess(r surgical expandable retractor, with the purpose of reducing morbidity and preserving the posterior muscle and ligamentous tension band. Results: This type of surgical approach provides adequate visualization and microsurgical resection of lesions and reduces muscle manipulation and devascularisation, preserving the tension of the ligament complex. There was minimal blood loss and a decrease in postoperative pain, with rapid start of rehabilitation and shorter hospitalization times. There were no intraoperative complications, and all patients recovered from their pre-operative symptoms. Conclusions: This novel surgical technique is feasible and adequate for the occipito-atlanto-axial complex, with better results than traditional procedures.

  8. Josephson tunnel junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M.P.

    2006-07-01

    Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al{sub 2}O{sub 3} tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or {pi} coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, {pi}) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-{pi} Josephson junction. At a certain temperature this 0-{pi} junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum {phi}{sub 0}. Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T {yields} 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

  9. Depth of planting and apical dominance on cuttings of red pitayaProfundidade de plantio e dominância apical na estaquia de pitaia vermelha

    Directory of Open Access Journals (Sweden)

    Virna Braga Marques

    2012-12-01

    Full Text Available This study was conducted to evaluate the effects of planting depth and breaking apical dominance on cutting of red pitaya Hylocereus undatus (Haw. Britton & Rose. The experiment was conducted in a randomized block design with four replications in a 2x3 factorial, with two kinds of cuttings (with or without apical dominance, cutting not sectioned and sectioned at 5 cm from the upper portion, and three planting depths (1.0, 5.0, and 10.0 cm and each plot consisted of ten 20 cm long cuttings. After 60 days of planting, counts of the number of shoots were began weekly and 90 days after planting survival rooting, number and length of shoots, dry weight of shoots and root dry mass were evaluated. Data were subjected to analysis of variance and polynomial regression at 5% significance level. The percentage of rooting and the survival were 100% in all treatments. With increasing depth of planting it was observed linear reduction in numbers of shoots, dry weight of shoot and root dry mass. The cladodes with apical dominance had longer shoots. The planting of red pitaya cuttings at 1 cm of planting depth with apical dominance is more suited to the production of nursery plants. O trabalho foi conduzido com o objetivo de avaliar os efeitos da profundidade de plantio e da quebra de dominância apical na estaquia de pitaia vermelha Hylocereus undatus (Haw. Britton & Rose. O experimento foi instalado no delineamento em blocos casualizados, com quatro repetições no esquema fatorial 2x3, sendo dois tipos de estacas (com e sem dominância apical, estacas não seccionadas e seccionadas a 5 cm da porção superior, e três profundidades de plantio (1,0; 5,0; 10,0 cm e cada parcela foi constituída de dez estacas com 20 cm de comprimento. Após 60 dias do plantio, foram iniciadas as avaliações semanais do número de brotações e aos 90 dias após o plantio foram avaliados sobrevivência, enraizamento, número e comprimento de brotações, massa seca das brota

  10. Model Building to Facilitate Understanding of Holliday Junction and Heteroduplex Formation, and Holliday Junction Resolution

    Science.gov (United States)

    Selvarajah, Geeta; Selvarajah, Susila

    2016-01-01

    Students frequently expressed difficulty in understanding the molecular mechanisms involved in chromosomal recombination. Therefore, we explored alternative methods for presenting the two concepts of the double-strand break model: Holliday junction and heteroduplex formation, and Holliday junction resolution. In addition to a lecture and…

  11. Analyses of Interactions Between Heparin and the Apical Surface Proteins of Plasmodium falciparum

    Science.gov (United States)

    Kobayashi, Kyousuke; Takano, Ryo; Takemae, Hitoshi; Sugi, Tatsuki; Ishiwa, Akiko; Gong, Haiyan; Recuenco, Frances C.; Iwanaga, Tatsuya; Horimoto, Taisuke; Akashi, Hiroomi; Kato, Kentaro

    2013-11-01

    Heparin, a sulfated glycoconjugate, reportedly inhibits the blood-stage growth of the malaria parasite Plasmodium falciparum. Elucidation of the inhibitory mechanism is valuable for developing novel invasion-blocking treatments based on heparin. Merozoite surface protein 1 has been reported as a candidate target of heparin; however, to better understand the molecular mechanisms involved, we characterized the molecules that bind to heparin during merozoite invasion. Here, we show that heparin binds only at the apical tip of the merozoite surface and that multiple heparin-binding proteins localize preferentially in the apical organelles. To identify heparin-binding proteins, parasite proteins were fractionated by means of heparin affinity chromatography and subjected to immunoblot analysis with ligand-specific antibodies. All tested members of the Duffy and reticulocyte binding-like families bound to heparin with diverse affinities. These findings suggest that heparin masks the apical surface of merozoites and blocks interaction with the erythrocyte membrane after initial attachment.

  12. Tratamiento de una periodontitis apical crónica reagudizada con pasta 3 Mix-MP

    OpenAIRE

    Hinostroza del Pino, Maycol; Unidad de Posgrado de la Facultad de Odontología de la Universidad Nacional Mayor de San Marcos, Perú. Departamento Académico de Estomatología Rehabilitadora de la Facultad de Odontología de la Universidad Nacional Mayor de San Marcos, Perú.; Salcedo-Moncada, Doris; Unidad de Posgrado de la Facultad de Odontología de la Universidad Nacional Mayor de San Marcos, Perú. Departamento Académico de Estomatología Rehabilitadora de la Facultad de Odontología de la Universidad Nacional Mayor de San Marcos, Perú.; Zambrano de la Peña, Sonia; Departamento Académico Médico Quirúrgico de la Facultad de Odontología de la Universidad Nacional Mayor de San Marcos, Perú.; Pineda-Mejía, Martha; Unidad de Posgrado de la Facultad de Odontología de la Universidad Nacional Mayor de San Marcos, Perú. Departamento Académico de Estomatología Rehabilitadora de la Facultad de Odontología de la Universidad Nacional Mayor de San Marcos, Perú.

    2016-01-01

    El propósito de este caso clínico es mostrar el uso como medicación intraconducto de la pasta de Hoshino (3Mix-MP). Paciente de sexo femenino acude a la clínica de posgrado con el diagnóstico clínico de necrosis pulpar con periodontitis apical crónica de la pieza 42. Se le realizó un tratamiento endodóntico en el año 2013; en el año 2014 regresa con lesión apical más severa y con un diagnóstico de periodontitis apical con fístula extraoral. La paciente no desea perder la pieza dentaria, por l...

  13. Gibberellin-enhanced elongation of inverted Pharbitis nil shoot prevents the release of apical dominance

    Science.gov (United States)

    Prasad, T. K.; Cline, M. G.

    1987-01-01

    Ethylene evolution resulting from the gravity stress of shoot inversion appears to induce the release of apical dominance in Pharbitis nil (L.) by inhibiting elongation of the inverted shoot. It has been previously demonstrated that this shoot inversion release of apical dominance can be prevented by promoting elongation in the inverted shoot via interference with ethylene synthesis or action. In the present study it was shown that apical dominance release can also be prevented by promoting elongation of the inverted shoot via treatment with gibberellic acid (GA3). A synergistic effect was observed when AgNO3, the ethylene action inhibitor, was applied with GA3. Both GA3 and AgNO3 increased ethylene production in the inverted shoot. These results are consistent with the view that it is ethylene-induced inhibition of elongation and not any direct effect of ethylene per se which is responsible for the outgrowth of the highest lateral bud.

  14. Isolated Left Ventricular Apical Hypoplasia with Right Ventricular Outflow Tract Obstruction: A Rare Combination.

    Science.gov (United States)

    Zhao, Yonghui; Zhang, Jiaying; Zhang, Jing

    2015-09-01

    Isolated left ventricular (LV) apical hypoplasia is a unusual and recently recognized congenital cardiac anomaly. A 19-year-old man was found to have an abnormal ECG and cardiac murmur identified during a routine health check since joining work. His ECG revealed normal sinus rhythm, right-axis deviation, poor R wave progression, and T wave abnormalities. On physical examination, a 2/6~3/6 systolic murmur was heard at the second intercostal space along the left sternal border. Subsequent echocardiography and cardiac magnetic resonance imaging confirmed the LV apical hypoplasia. Of note, we first found that LV apical hypoplasia was accompanied by RV outflow tract obstruction due to exaggerated rightward bulging of the basal-anterior septum during systole. A close follow-up was performed for the development of heart failure, pulmonary hypertension, and potentially tachyarrhythmia.

  15. Three-dimensional Organization of Layered Apical Cytoskeletal Networks Associated with Mouse Airway Tissue Development

    Science.gov (United States)

    Tateishi, Kazuhiro; Nishida, Tomoki; Inoue, Kanako; Tsukita, Sachiko

    2017-03-01

    The cytoskeleton is an essential cellular component that enables various sophisticated functions of epithelial cells by forming specialized subcellular compartments. However, the functional and structural roles of cytoskeletons in subcellular compartmentalization are still not fully understood. Here we identified a novel network structure consisting of actin filaments, intermediate filaments, and microtubules directly beneath the apical membrane in mouse airway multiciliated cells and in cultured epithelial cells. Three-dimensional imaging by ultra-high voltage electron microscopy and immunofluorescence revealed that the morphological features of each network depended on the cell type and were spatiotemporally integrated in association with tissue development. Detailed analyses using Odf2 mutant mice, which lack ciliary basal feet and apical microtubules, suggested a novel contribution of the intermediate filaments to coordinated ciliary beating. These findings provide a new perspective for viewing epithelial cell differentiation and tissue morphogenesis through the structure and function of apical cytoskeletal networks.

  16. Listeria monocytogenes internalin B activates junctional endocytosis to accelerate intestinal invasion.

    Directory of Open Access Journals (Sweden)

    Mickey Pentecost

    2010-05-01

    Full Text Available Listeria monocytogenes (Lm uses InlA to invade the tips of the intestinal villi, a location at which cell extrusion generates a transient defect in epithelial polarity that exposes the receptor for InlA, E-cadherin, on the cell surface. As the dying cell is removed from the epithelium, the surrounding cells reorganize to form a multicellular junction (MCJ that Lm exploits to find its basolateral receptor and invade. By examining individual infected villi using 3D-confocal imaging, we uncovered a novel role for the second major invasin, InlB, during invasion of the intestine. We infected mice intragastrically with isogenic strains of Lm that express or lack InlB and that have a modified InlA capable of binding murine E-cadherin and found that Lm lacking InlB invade the same number of villi but have decreased numbers of bacteria within each infected villus tip. We studied the mechanism of InlB action at the MCJs of polarized MDCK monolayers and find that InlB does not act as an adhesin, but instead accelerates bacterial internalization after attachment. InlB locally activates its receptor, c-Met, and increases endocytosis of junctional components, including E-cadherin. We show that MCJs are naturally more endocytic than other sites of the apical membrane, that endocytosis and Lm invasion of MCJs depends on functional dynamin, and that c-Met activation by soluble InlB or hepatocyte growth factor (HGF increases MCJ endocytosis. Also, in vivo, InlB applied through the intestinal lumen increases endocytosis at the villus tips. Our findings demonstrate a two-step mechanism of synergy between Lm's invasins: InlA provides the specificity of Lm adhesion to MCJs at the villus tips and InlB locally activates c-Met to accelerate junctional endocytosis and bacterial invasion of the intestine.

  17. Measurement of Aharonov-Casher effect in a Josephson junction chain

    Science.gov (United States)

    Pop, Ioan Mihai; Lecocq, Florent; Pannetier, Bernard; Buisson, Olivier; Guichard, Wiebke

    2011-03-01

    We have recently measured the effect of superconducting phase-slips on the ground state of a Josephson junction chain and a rhombi chain. Here we report clear evidence of Aharonov-Casher effect in a chain of Josephson junctions. This phenomenon is the dual of the well known Aharonov-Bohm interference. Using a capacitively coupled gate to the islands of the chain, we induce oscillations of the supercurrent by tuning the polarization charges on the islands. We observe complex interference patterns for different quantum phase slip amplitudes, that we understand quantitatively as Aharonov-Casher vortex interferences. European STREP MIDAS.

  18. Surgical Outcomes and Safety of Robotic Sacrocolpopexy in Women With Apical Pelvic Organ Prolapse

    Science.gov (United States)

    2017-01-01

    Purpose This study aimed to investigate the surgical outcomes and safety of robotic sacrocolpopexy (RSC) in patients with uterine/vaginal vault prolapse. Methods Between January 2009 and June 2015, 16 women with apical prolapse underwent RSC. Pelvic organ prolapse quantification (POP-Q) examination was performed, and treatment success was defined as the presence of grade 0 or I apical prolapse upon POP-Q examination at the final follow-up. Pelvic floor distress inventory-short form 20 (PFDI-SF 20) was administered at every follow-up. A treatment satisfaction questionnaire was administered by telephone to evaluate patient satisfaction with the operation. Results Median age was 65 years (interquartile range [IQR], 56–68 years), and follow-up duration was 25.3 months (IQR, 5.4–34.0 months). Thirteen women (81.3%) had ≥grade III apical prolapse. Operation time was 251 minutes (IQR, 236–288 minutes), and blood loss was 75 mL (IQR, 50–150 mL). Median hospital stay was 4 days (IQR, 3–5 days). At the final follow-up, treatment success was reported in all patients, who presented grade 0 (n=8, 57.1%) and grade I (n=6, 42.9%) apical prolapse. Dramatic improvements in PFDI-SF 20 scores were noted after RSC (from 39 to 4; P=0.001). Most patients (12 of 13) were satisfied with RSC. An intraoperative complication (sacral venous plexus injury) was reported in 1 patient, and there was no conversion to open surgery. Mesh erosion was not reported. Conclusions RSC is an efficient and safe surgical option for apical prolapse repair. Most patients were satisfied with RSC. Thus, RSC might be one of the best treatment options for apical prolapse in women. PMID:28361513

  19. Cytokinin is required for escape but not release from auxin mediated apical dominance

    Science.gov (United States)

    Müller, Dörte; Waldie, Tanya; Miyawaki, Kaori; To, Jennifer PC; Melnyk, Charles W; Kieber, Joseph J; Kakimoto, Tatsuo; Leyser, Ottoline

    2015-01-01

    Auxin produced by an active primary shoot apex is transported down the main stem and inhibits the growth of the axillary buds below it, contributing to apical dominance. Here we use Arabidopsis thaliana cytokinin (CK) biosynthetic and signalling mutants to probe the role of CK in this process. It is well established that bud outgrowth is promoted by CK, and that CK synthesis is inhibited by auxin, leading to the hypothesis that release from apical dominance relies on an increased supply of CK to buds. Our data confirm that decapitation induces the expression of at least one ISOPENTENYLTRANSFERASE (IPT) CK biosynthetic gene in the stem. We further show that transcript abundance of a clade of the CK-responsive type-A Arabidopsis response regulator (ARR) genes increases in buds following CK supply, and that, contrary to their typical action as inhibitors of CK signalling, these genes are required for CK-mediated bud activation. However, analysis of the relevant arr and ipt multiple mutants demonstrates that defects in bud CK response do not affect auxin-mediated bud inhibition, and increased IPT transcript levels are not needed for bud release following decapitation. Instead, our data suggest that CK acts to overcome auxin-mediated bud inhibition, allowing buds to escape apical dominance under favourable conditions, such as high nitrate availability. Significance Statement It has been proposed that the release of buds from auxin-mediated apical dominance following decapitation requires increased cytokinin biosynthesis and consequent increases in cytokinin supply to buds. Here we show that in Arabidopsis, increases in cytokinin appear to be unnecessary for the release of buds from apical dominance, but rather allow buds to escape the inhibitory effect of apical auxin, thereby promoting bud activation in favourable growth conditions. PMID:25904120

  20. Identification of regions required for apical membrane localization of human multidrug resistance protein 2.

    Science.gov (United States)

    Bandler, Paul E; Westlake, Christopher J; Grant, Caroline E; Cole, Susan P C; Deeley, Roger G

    2008-07-01

    Multidrug resistance proteins MRP1 and MRP2 transport a wide range of endo- and xenobiotics. However, with the exception of certain parts of the brain, MRP1 traffics to basolateral membranes of polarized cells, whereas MRP2 is apical in location and thus it is particularly important for systemic elimination of such compounds. Different regions of MRP1 and MRP2 seem to target them to their respective membrane locations. In addition to two "core" membrane spanning domains (MSDs) characteristic of ATP-binding cassette transporters, MRP1 and MRP2 have a third NH2-terminal MSD (MSD0), which is not required for basolateral targeting of MRP1, or for transport of at least some substrates. Here, we demonstrate that all elements necessary for apical targeting of MRP2 reside in MSD0 and the adjacent cytoplasmic loop (CL) 3. Furthermore, we show that this region of MRP2 can target the core of MRP1 to an exclusively apical location. Within MRP2 CL3, we identified a lysine-rich element that is essential for apical targeting. When introduced into MRP1, this element alone is sufficient to result in partial apical localization. However, exclusive targeting to the apical membrane seems to require the integrity of the entire region encompassing MSD0 and CL3 of MRP2. Because CL3 of MRP1 is critical for binding, transport, or both of several compounds, we also examined the function of hybrids containing all, or portions of MRP2 MSD0 and CL3. Our results indicate that CL3 is important for interaction with both the glutathione and glucuronide conjugates tested, but that different regions may be involved.

  1. Increasing gap junctional coupling: a tool for dissecting the role of gap junctions

    DEFF Research Database (Denmark)

    Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin;

    2007-01-01

    . In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing......Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes...... the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs...

  2. Acoustic minor losses in high amplitude resonators with single-sided junctions

    Science.gov (United States)

    Doller, Andrew J.

    Steady flow engineering handbooks like Idelchik20 do not exist for investigators interested in acoustic (oscillating) fluid flows in complex resonators. Measurements of acoustic minor loss coefficients are presented in this dissertation for a limited number of resonator configurations having single-sided junctions. While these results may be useful, the greater purpose of this work is to provide a set of controlled measurements that can be used to benchmark computational models of acoustic flows used for more complicated resonator structures. The experiments are designed around a driver operating at 150 Hz enabling acoustic pressures in excess of 10k Pa in liquid cooled, temperature controlled resonators with 90°, 45° and 25° junctions. These junctions join a common 109 cm long 4.7 cm diameter section to a section of 8.4 mm diameter tube making two sets of resonators: one set with a small diameter length approximately a quarter-wavelength (45 cm), the other approximately a half-wavelength (112 cm). The long resonators have a velocity node at the junction; the short resonators have a velocity anti-node generating the greatest minor losses. Input power is measured by an accelerometer and a pressure transducer at the driver. A pressure sensor at the rigid termination measures radiation pressure from the driver and static junction pressure, as well as the acoustic pressure used to calculate linear thermal and viscous resonator wall losses. At the largest amplitudes, the 90° junction was found to dissipate as much as 0.3 Watt, 1/3 the power of linear losses alone. For each junction, the power dissipation depends on acoustic pressure differently: pressure cubed for the 90°, pressure to the 3.76 for the 45° and pressure to the 4.48 for the 25°. Common among all resonators, blowing acoustic half-cycle minor losses (KB) are excited at lower amplitudes than the suction half-cycle (KS) minor losses. Data collected for the 90° junction shows KB reaches an asymptotic

  3. Reestablishing the Function and Esthetics in Traumatized Permanent Teeth with Large Apical Lesion

    Directory of Open Access Journals (Sweden)

    Alexandra Rubin Cocco

    2016-01-01

    Full Text Available Dental trauma is a challenge for dental integrity and can lead to pulp necrosis. The clinical case reports the diagnosis of a maxillary right central incisor traumatized and its multidisciplinary treatment. Calcium hydroxide material was used to perform the processing apexification. An apical surgery was carried out to remove the apical periodontitis and to return the aesthetics to the patient; internal and external tooth whitening in maxillary right central incisor was performed. We conclude that surgery associated with the root filling in the central incisor led to a successful completion. Moreover, it is of utmost importance to demonstrate the interaction between the various areas of dentistry.

  4. Frecuencia de periodontitis apical en tratamientos endodónticos de pregrado

    OpenAIRE

    P. León; Ilabaca, M.J.; M Alcota; González, F.E.

    2011-01-01

    La periodontitis apical es una enfermedad de los tejidos periapicales de etiología bacteriana. Su tratamiento requiere erradicar los microorganismos del conducto radicular y obturarlo para lograr la reparación posterior. El objetivo de éste trabajo fue determinar la frecuencia de periodontitis apical en la población que asiste a la clínica de Endodoncia de la Facultad de Odontología de la Universidad de Chile y su relación con diferentes variables: diagnóstico específico, edad, sexo, agudas v...

  5. Usefulness of contrast computed tomography to detect left ventricular apical thrombus associated with takotsubo cardiomyopathy.

    Science.gov (United States)

    Ouchi, Kotaro; Nakamura, Fumitaka; Ikutomi, Masayasu; Oshima, Tsukasa; Ishiwata, Jumpei; Shinohara, Hiroki; Kouzaki, Tsunashi; Amaki, Toshihiro

    2016-05-01

    Left ventricular (LV) apical thrombus can rarely occur during the early phase of takotsubo cardiomyopathy. We report such a case that was depicted clearly in contrast computed tomography (CT) but not in initial echocardiography. Because LV thrombus may lead to thromboembolic events, we should evaluate all patients with takotsubo cardiomyopathy for the presence of a LV thrombus. LV thrombus is generally recognized with echocardiography in the course of follow-up, but limited depiction of the LV apex with echocardiography can make evaluation of LV thrombus difficult. Contrast CT is useful to detect LV apical thrombus associated with takotsubo cardiomyopathy.

  6. Apical Ballooning Syndrome (Takotsubo Cardiomyopathy after Permanent Dual-Chamber Pacemaker Implantation

    Directory of Open Access Journals (Sweden)

    Armando Gardini

    2012-01-01

    Full Text Available Apical ballooning syndrome, also called takotsubo cardiomyopathy, has been recently reported. It may mimic acute myocardial infarction and is typically observed in postmenopausal women after stressful events. A 75-year-old female after permanent dual chamber pacemaker implant complained of chest pain with repolarization alterations suggesting acute myocardial ischemia. Echocardiography showed a left ventricle with akinesia of the apical portions and reduced global systolic function. The patient was treated with antithrombotic agents and intravenous nitrates. No coronary lesions were found at angiography. At ventriculography, a typical takotsubo-like shape of the left ventricle was observed. The clinical and echocardiographic picture normalized at discharge.

  7. Frecuencia de periodontitis apical en tratamientos endodónticos de pregrado

    OpenAIRE

    León, P; Ilabaca,MJ; Alcota,M; González,FE

    2011-01-01

    La periodontitis apical es una enfermedad de los tejidos periapicales de etiología bacteriana. Su tratamiento requiere erradicar los microorganismos del conducto radicular y obturarlo para lograr la reparación posterior. El objetivo de éste trabajo fue determinar la frecuencia de periodontitis apical en la población que asiste a la clínica de Endodoncia de la Facultad de Odontología de la Universidad de Chile y su relación con diferentes variables: diagnóstico específico, edad, sexo, agudas v...

  8. Criterios Clínicos y Radiológicos de la Periodontitis Apical.

    OpenAIRE

    Jiménez Planas, Amparo

    2017-01-01

    Se realiza un trabajo con 271 casos diagnosticados de periodontitis apical, clínica o radiológicamente, en los que se valoran parámetros clínicos y radiológicos que nos permitan delimitar las diferentes formas clínicas de este proceso. se propone, como consecuencia de los resultados, una clasificación clara, simple, coherente y evolutiva de la periodontitis apical y se hacen diversas consideraciones sobre la nomenclatura, etiología, cl...

  9. Evolutionary change mimicking apical hypertrophic cardiomyopathy in a patient with takotsubo cardiomyopathy.

    Science.gov (United States)

    Hwang, Hui-Jeong; Lee, Hyae-Min; Yang, In-Ho; Kim, Dong-Hee; Byun, Jong-Kyu; Sohn, Il Suk

    2014-11-01

    In this report, we introduce a case of thickening of the involved left ventricular apical segment on echocardiography and deep T-wave inversions in precordial leads on electrocardiography transiently seen in the course of recovery from biventricular takotsubo cardiomyopathy, mimicking apical hypertrophic cardiomyopathy. This result suggests that the echocardiographic finding of transient myocardial edema can be identified by cardiac magnetic resonance imaging in takotsubo cardiomyopathy. Additionally, it persisted a few weeks after full functional recovery. We believe that this case will contribute in part toward clarifying the pathophysiology of takotsubo cardiomyopathy.

  10. Cone Reconstruction of Atypical Ebstein Anomaly Associated with Right Ventricular Apical Hypoplasia.

    Science.gov (United States)

    Reddin, Gemma; Poterucha, Joseph T; Dearani, Joseph A; Warnes, Carole A; Cetta, Frank

    2016-02-01

    Cone reconstruction for tricuspid valve repair has revolutionized the surgical treatment of Ebstein anomaly. We present the case of a 58-year-old woman with atypical Ebstein anomaly and right ventricular apical hypoplasia who was spared from palliative shunt physiology by our use of cone reconstruction. Compared with other techniques, cone reconstruction of the tricuspid valve more closely replicates normal valvular anatomy and function. This surgical procedure can be applied to many anatomic variations of Ebstein anomaly, as in our patient's apparently unique instance of atypical Ebstein anomaly with right ventricular apical hypoplasia.

  11. Rectification in tunneling junctions: 2,2'-bipyridyl-terminated n-alkanethiolates.

    Science.gov (United States)

    Yoon, Hyo Jae; Liao, Kung-Ching; Lockett, Matthew R; Kwok, Sen Wai; Baghbanzadeh, Mostafa; Whitesides, George M

    2014-12-10

    Molecular rectification is a particularly attractive phenomenon to examine in studying structure-property relationships in charge transport across molecular junctions, since the tunneling currents across the same molecular junction are measured, with only a change in the sign of the bias, with the same electrodes, molecule(s), and contacts. This type of experiment minimizes the complexities arising from measurements of current densities at one polarity using replicate junctions. This paper describes a new organic molecular rectifier: a junction having the structure Ag(TS)/S(CH2)11-4-methyl-2,2'-bipyridyl//Ga2O3/EGaIn (Ag(TS): template-stripped silver substrate; EGaIn: eutectic gallium-indium alloy) which shows reproducible rectification with a mean r(+) = |J(+1.0 V)|/|J(-1.0 V)| = 85 ± 2. This system is important because rectification occurs at a polarity opposite to that of the analogous but much more extensively studied systems based on ferrocene. It establishes (again) that rectification is due to the SAM, and not to redox reactions involving the Ga2O3 film, and confirms that rectification is not related to the polarity in the junction. Comparisons among SAM-based junctions incorporating the Ga2O3/EGaIn top electrode and a variety of heterocyclic terminal groups indicate that the metal-free bipyridyl group, not other features of the junction, is responsible for the rectification. The paper also describes a structural and mechanistic hypothesis that suggests a partial rationalization of values of rectification available in the literature.

  12. T-junction cross-flow mixing with thermally driven density stratification

    Energy Technology Data Exchange (ETDEWEB)

    Kickhofel, John, E-mail: jkickhofel@gmail.com [Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8057 Zurich (Switzerland); Prasser, Horst-Michael, E-mail: prasser@lke.mavt.ethz.ch [Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8057 Zurich (Switzerland); Selvam, P. Karthick, E-mail: karthick.selvam@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Laurien, Eckart, E-mail: eckart.laurien@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Kulenovic, Rudi, E-mail: rudi.kulenovic@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany)

    2016-12-01

    Highlights: • Mesh sensor for realistic nuclear thermal hydraulic scenarios is demonstrated. • Flow temperature behavior across a wide range of Richardson numbers measured. • Upstream stratified flow in the T-junction results in a thermal shock scenario. • Large, stable near-wall thermal gradients exist in spite of turbulent flows. - Abstract: As a means of further elucidating turbulence- and stratification-driven thermal fatigue in the vicinity of T-junctions in nuclear power plants, a series of experiments have been conducted at the high temperature high pressure fluid–structure interaction T-junction facility of the University of Stuttgart with novel fluid measurement instrumentation. T-junction mixing with large fluid temperature gradients results in complex flow behavior, the result of density driven effects. Deionized water mixing at temperature differences of up to 232 K at 7 MPa pressure have been investigated in a T-junction with main pipe diameter 71.8 mm and branch line diameter 38.9 mm. The experiments have been performed with fixed flow rates of 0.4 kg/s in the main pipe and 0.1 kg/s in the branch line. A novel electrode-mesh sensor compatible with the DN80 PN100 pipeline upstream and downstream of the T-junction has been utilized as a temperature sensor providing a high density information in the pipe cross-section in both space and time. Additionally, in-flow and in-wall thermocouples quantify the damping of thermal fluctuations by the wall material. The results indicate that large inflow temperature differences lead to strong turbulence damping, and ultimately stable stratification extending both downstream and upstream of the T-junction resulting in large local thermal gradients.

  13. A rare nucleotide base tautomer in the structure of an asymmetric DNA junction.

    Science.gov (United States)

    Khuu, Patricia; Ho, P Shing

    2009-08-25

    The single-crystal structure of a DNA Holliday junction assembled from four unique sequences shows a structure that conforms to the general features of models derived from similar constructs in solution. The structure is a compact stacked-X form junction with two sets of stacked B-DNA-type arms that coaxially stack to form semicontinuous duplexes interrupted only by the crossing of the junction. These semicontinuous helices are related by a right-handed rotation angle of 56.5 degrees, which is nearly identical to the 60 degree angle in the solution model but differs from the more shallow value of approximately 40 degrees for previous crystal structures of symmetric junctions that self-assemble from single identical inverted-repeat sequences. This supports the model in which the unique set of intramolecular interactions at the trinucleotide core of the crossing strands, which are not present in the current asymmetric junction, affects both the stability and geometry of the symmetric junctions. An unexpected result, however, is that a highly wobbled A.T base pair, which is ascribed here to a rare enol tautomer form of the thymine, was observed at the end of a CCCC/GGGG sequence within the stacked B-DNA arms of this 1.9 A resolution structure. We suggest that the junction itself is not responsible for this unusual conformation but served as a vehicle for the study of this CG-rich sequence as a B-DNA duplex, mimicking the form that would be present in a replication complex. The existence of this unusual base lends credence to and defines a sequence context for the "rare tautomer hypothesis" as a mechanism for inducing transition mutations during DNA replication.

  14. Dislocation Multi-junctions and Strain Hardening

    Energy Technology Data Exchange (ETDEWEB)

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T

    2006-06-20

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  15. Holliday junction processing enzymes as guardians of genome stability.

    Science.gov (United States)

    Sarbajna, Shriparna; West, Stephen C

    2014-09-01

    Holliday junctions (HJs) are four-stranded DNA intermediates that arise during the recombinational repair of DNA double-strand breaks (DSBs). Their timely removal is crucial for faithful chromosome segregation and genome stability. In mammalian cells, HJs are processed by the BTR (BLM-topoisomerase IIIα-RMI1-RMI2) complex, the SLX-MUS (SLX1-SLX4-MUS81-EME1) complex, and the GEN1 resolvase. Recent studies have linked the deficiency of one or more of these enzymes to perturbed DNA replication, impaired crosslink repair, chromosomal instability, and defective mitoses, coupled with the transmission of widespread DNA damage and high levels of mortality. We review these key advances and how they have cemented the status of HJ-processing enzymes as guardians of genome integrity and viability in mammalian cells. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Experimental demonstration of Aharonov-Casher interference in a Josephson junction circuit

    Science.gov (United States)

    Pop, I. M.; Douçot, B.; Ioffe, L.; Protopopov, I.; Lecocq, F.; Matei, I.; Buisson, O.; Guichard, W.

    2012-03-01

    A neutral quantum particle with magnetic moment encircling a static electric charge acquires a quantum-mechanical phase (Aharonov-Casher effect). In superconducting electronics, the neutral particle becomes a fluxon that moves around superconducting islands connected by Josephson junctions. The full understanding of this effect in systems of many junctions is crucial for the design of novel quantum circuits. Here, we present measurements and quantitative analysis of fluxon interference patterns in a six Josephson junction chain. In this multijunction circuit, the fluxon can encircle any combination of charges on five superconducting islands, resulting in a complex pattern. We compare the experimental results with predictions of a simplified model that treats fluxons as independent excitations and with the results of the full diagonalization of the quantum problem. Our results demonstrate the accuracy of the fluxon interference description and the quantum coherence of these arrays.

  17. Frenectomy with semilunar coronally repositioned flap: A single stage approach - simple solution for complex problem

    OpenAIRE

    Deshmukh, Jeevanand; Khatri, Richa; Fernandes, Bennete; Kulkarni, Vinaya Kumar; Singh, Shubhra

    2015-01-01

    Gingival recession is defined as the displacement of gingival margin apical to cementoenamel junction. Aberrant frenum attachment can contribute to the progression of recession by generating tension on the marginal tissues. Treating such defects is a two stage procedure-frenectomy and recession coverage procedure. New techniques are developed to increase the predictability, reduce patient discomfort and number of surgical sites. Also, these techniques try to satisfy patients esthetic demands,...

  18. Created-by-current states in long Josephson junctions

    Science.gov (United States)

    Boyadjiev, T. L.; Andreeva, O. Yu.; Semerdjieva, E. G.; Shukrinov, Yu. M.

    2008-08-01

    Critical curves "critical current-external magnetic field" of long Josephson junctions with inhomogeneity and variable width are studied. We demonstrate the existence of regions of magnetic field where some fluxon states are stable only if the external current through the junction is different from zero. Position and size of such regions depend on the length of the junction, its geometry, parameters of inhomogeneity and form of the junction. The noncentral (left and right) pure fluxon states appear in the inhomogeneous Josephson junction with the increase in the junction length. We demonstrate new bifurcation points with change in width of the inhomogeneity and amplitude of the Josephson current through the inhomogeneity.

  19. Comparative analysis of system identification techniques for nonlinear modeling of the neuron-microelectrode junction.

    Science.gov (United States)

    Khan, Saad Ahmad; Thakore, Vaibhav; Behal, Aman; Bölöni, Ladislau; Hickman, James J

    2013-03-01

    Applications of non-invasive neuroelectronic interfacing in the fields of whole-cell biosensing, biological computation and neural prosthetic devices depend critically on an efficient decoding and processing of information retrieved from a neuron-electrode junction. This necessitates development of mathematical models of the neuron-electrode interface that realistically represent the extracellular signals recorded at the neuroelectronic junction without being computationally expensive. Extracellular signals recorded using planar microelectrode or field effect transistor arrays have, until now, primarily been represented using linear equivalent circuit models that fail to reproduce the correct amplitude and shape of the signals recorded at the neuron-microelectrode interface. In this paper, to explore viable alternatives for a computationally inexpensive and efficient modeling of the neuron-electrode junction, input-output data from the neuron-electrode junction is modeled using a parametric Wiener model and a Nonlinear Auto-Regressive network with eXogenous input trained using a dynamic Neural Network model (NARX-NN model). Results corresponding to a validation dataset from these models are then employed to compare and contrast the computational complexity and efficiency of the aforementioned modeling techniques with the Lee-Schetzen technique of cross-correlation for estimating a nonlinear dynamic model of the neuroelectronic junction.

  20. pn-Junction Delineation in Si Devices Using Scanning Capacitance Spectroscopy

    Science.gov (United States)

    Edwards, Hal

    2000-03-01

    The scanning capacitance microscope (SCM) is a carrier-sensitive imaging tool based upon the well-known scanning-probe microscope (SPM). Scanning capacitance spectroscopy (SCS) is a new way to utilize an SCM to delineate pn junctions in Si devices. SCS produces two-dimensional pn-junction maps that show features as small as 10 nm. SCS also provides an estimate of the pn-junction depletion width and hence the doping level near the pn junction. We report SCS measurements of deep-submicron field-effect transistors, showing the source-drain extender profile. We show SCM and SCS data in a failure-analysis application, in which we determined the cause of a leaky field-effect transistor. SCM and SCS are powerful tools for Si bipolar transistors, in which the doping-related structures are quite complex. We show microscopic evidence of the narrow-emitter effect, and image the width of the pn junction to explain an electric field-induced hot-carrier reliability issue. We show a comparison of top-view and cross-sectional SCS measurements of nwell-nwell shallow-trench isolation structures, to reveal the effects of photoresist scumming in sub-design-rule isolation widths. We show initial results on a method to delineate constant-potential contours within the depletion region. We discuss the limits to our present understanding of SCM and SCS and some potential sources of error.