Science.gov

Sample records for disrupts apical junctional

  1. Microtubules regulate disassembly of epithelial apical junctions

    PubMed Central

    Ivanov, Andrei I; McCall, Ingrid C; Babbin, Brian; Samarin, Stanislav N; Nusrat, Asma; Parkos, Charles A

    2006-01-01

    Background Epithelial tight junction (TJ) and adherens junction (AJ) form the apical junctional complex (AJC) which regulates cell-cell adhesion, paracellular permeability and cell polarity. The AJC is anchored on cytoskeletal structures including actin microfilaments and microtubules. Such cytoskeletal interactions are thought to be important for the assembly and remodeling of apical junctions. In the present study, we investigated the role of microtubules in disassembly of the AJC in intestinal epithelial cells using a model of extracellular calcium depletion. Results Calcium depletion resulted in disruption and internalization of epithelial TJs and AJs along with reorganization of perijunctional F-actin into contractile rings. Microtubules reorganized into dense plaques positioned inside such F-actin rings. Depolymerization of microtubules with nocodazole prevented junctional disassembly and F-actin ring formation. Stabilization of microtubules with either docetaxel or pacitaxel blocked contraction of F-actin rings and attenuated internalization of junctional proteins into a subapical cytosolic compartment. Likewise, pharmacological inhibition of microtubule motors, kinesins, prevented contraction of F-actin rings and attenuated disassembly of apical junctions. Kinesin-1 was enriched at the AJC in cultured epithelial cells and it also accumulated at epithelial cell-cell contacts in normal human colonic mucosa. Furthermore, immunoprecipitation experiments demonstrated association of kinesin-1 with the E-cadherin-catenin complex. Conclusion Our data suggest that microtubules play a role in disassembly of the AJC during calcium depletion by regulating formation of contractile F-actin rings and internalization of AJ/TJ proteins. PMID:16509970

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

    PubMed

    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.

  3. Glutamine Supplementation Attenuates Ethanol-Induced Disruption of Apical Junctional Complexes in Colonic Epithelium and Ameliorates Gut Barrier Dysfunction and Fatty Liver in Mice

    PubMed Central

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

    2015-01-01

    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 glutamine 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 Gln-free diet and absent in mice fed 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. PMID:26365579

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

    PubMed

    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.

  5. Virus interaction with the apical junctional complex.

    PubMed

    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.

  6. Breaking into the epithelial apical-junctional complex--news from pathogen hackers.

    PubMed

    Vogelmann, Roger; Amieva, Manuel R; Falkow, Stanley; Nelson, W James

    2004-02-01

    The epithelial apical-junctional complex is a key regulator of cellular functions. In addition, it is an important target for microbial pathogens that manipulate the cell to survive, proliferate and sometimes persist within a host. Out of a myriad of potential molecular targets, some bacterial and viral pathogens have selected a subset of protein targets at the apical-junctional complex of epithelial cells. Studying how microbes use these targets also teaches us about the inherent physiological properties of host molecules in the context of normal junctional structure and function. Thus, we have learned that three recently uncovered components of the apical-junctional complex of the Ig superfamily--junctional adhesion molecule, Nectin and the coxsackievirus and adenovirus receptor--are important regulators of junction structure and function and represent critical targets of microbial virulence gene products.

  7. Adherens junctions determine the apical position of the midbody during follicular epithelial cell division.

    PubMed

    Morais-de-Sá, Eurico; Sunkel, Claudio

    2013-08-01

    Cytokinesis is asymmetric along the apical-basal axis of epithelial cells, positioning the midbody near the apical domain. However, little is known about the mechanism and purpose of this asymmetry. We use live imaging of Drosophila follicle cell division to show that asymmetric cytokinesis does not result from intrinsic polarization of the main contractile ring components. We show that adherens junctions (AJs) maintain close contact with the apical side of the contractile ring during cytokinesis. Asymmetric distribution of AJ components within follicle cells and in the otherwise unpolarized S2 cells is sufficient to recruit the midbody, revealing that asymmetric cytokinesis is determined by apical AJs in the epithelia. We further show that ectopic midbody localization induces epithelial invaginations, shifting the position of the apical interface between daughter cells relative to the AB axis of the tissue. Thus, apical midbody localization is essential to maintain epithelial tissue architecture during proliferation.

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

    PubMed

    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.

  9. EVALUATION OF THE APICAL INFILTRATION AFTER ROOT CANAL DISRUPTION AND OBTURATION

    PubMed Central

    Gomes, João Eduardo; Hopp, Renato Nicolás; Bernabé, Pedro Felício Estrada; Nery, Mauro Juvenal; Otoboni, José Arlindo; Dezan, Elói

    2008-01-01

    The aim of this study was to evaluate two root canal filling techniques used in teeth that had their apical foramen disrupted and compare the apical infiltration with an ideal clinical situation. Twenty-seven freshly extracted single-rooted teeth were selected and radiographed to confirm the existence of a single and straight root canal. The crowns were removed at a mean distance of 11 mm from the apex. The teeth had the root canals instrumented and were randomly assigned to 3 groups (n=9): ND group - root canals were filled using the lateral compaction technique and no disruption was performed; DRF group - the apical constriction was disrupted by advancing a #40 K-file 1 mm beyond the original working length, the canals were reinstrumented to create an apical ledge at 1 mm from the apical foramen and were obturated with a master gutta-percha cone with same size as the last file used for reinstrumentation; DF group - the teeth had the apical constriction disrupted and the canals were obturated with a master gutta-percha cone that fit at 1 mm from the apex. The teeth were submitted to dye leakage test with Rhodamine B for 7 days, using vaccum on the initial 5 min. The teeth were sectioned longitudinally and the leakage was measured in a linear fashion from apex to crown. There was no statistically significant difference (p>0.05) between the groups that had the apical foramen disrupted (DF, DRF), but significant difference was found between the disrupted groups and the non-disrupted one (p<0.01). In conclusion, none of the evaluated techniques was able to prevent apical infiltration, so working length so the working length determination has to be established and maintained carefully. PMID:19089232

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

    PubMed Central

    Baranwal, Somesh

    2015-01-01

    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. PMID:25792565

  11. Phosphatidylcholine passes through lateral tight junctions for paracellular transport to the apical side of the polarized intestinal tumor cell-line CaCo2.

    PubMed

    Stremmel, Wolfgang; Staffer, Simone; Gan-Schreier, Hongying; Wannhoff, Andreas; Bach, Margund; Gauss, Annika

    2016-09-01

    Phosphatidylcholine (PC) is the most abundant phospholipid in intestinal mucus, indicative of a specific transport system across the mucosal epithelium to the intestinal lumen. To elucidate this transport mechanism, we employed a transwell tissue culture system with polarized CaCo2 cells. It was shown that PC could not substantially be internalized by the cells. However, after basal application of increasing PC concentrations, an apical transport of 47.1±6.3nmolh(-1)mMPC(-1) was observed. Equilibrium distribution studies with PC applied in equal concentrations to the basal and apical compartments showed a 1.5-fold accumulation on the expense of basal PC. Disruption of tight junctions (TJ) by acetaldehyde or PPARγ inhibitors or by treatment with siRNA to TJ proteins suppressed paracellular transport by at least 50%. Transport was specific for the choline containing the phospholipids PC, lysoPC and sphingomyelin. We showed that translocation is driven by an electrochemical gradient generated by apical accumulation of Cl(-) and HCO3(-) through CFTR. Pretreatment with siRNA to mucin 3 which anchors in the apical plasma membrane of mucosal cells inhibited the final step of luminal PC secretion. PC accumulates in intestinal mucus using a paracellular, apically directed transport route across TJs.

  12. Arp2/3 promotes junction formation and maintenance in the Caenorhabditis elegans intestine by regulating membrane association of apical proteins

    PubMed Central

    Bernadskaya, Yelena Y.; Patel, Falshruti B.; Hsu, Hsiao-Ting; Soto, Martha C.

    2011-01-01

    It has been proposed that Arp2/3, which promotes nucleation of branched actin, is needed for epithelial junction initiation but is less important as junctions mature. We focus here on how Arp2/3 contributes to the Caenorhabditis elegans intestinal epithelium and find important roles for Arp2/3 in the maturation and maintenance of junctions in embryos and adults. Electron microscope studies show that embryos depleted of Arp2/3 form apical actin-rich microvilli and electron-dense apical junctions. However, whereas apical/basal polarity initiates, apical maturation is defective, including decreased apical F-actin enrichment, aberrant lumen morphology, and reduced accumulation of some apical junctional proteins, including DLG-1. Depletion of Arp2/3 in adult animals leads to similar intestinal defects. The DLG-1/AJM-1 apical junction proteins, and the ezrin–radixin–moesin homologue ERM-1, a protein that connects F-actin to membranes, are required along with Arp2/3 for apical F-actin enrichment in embryos, whereas cadherin junction proteins are not. Arp2/3 affects the subcellular distribution of DLG-1 and ERM-1. Loss of Arp2/3 shifts both ERM-1 and DLG-1 from pellet fractions to supernatant fractions, suggesting a role for Arp2/3 in the distribution of membrane-associated proteins. Thus, Arp2/3 is required as junctions mature to maintain apical proteins associated with the correct membranes. PMID:21697505

  13. Overexpressed miRNA-155 dysregulates intestinal epithelial apical junctional complex in severe acute pancreatitis

    PubMed Central

    Tian, Rui; Wang, Rui-Lan; Xie, Hui; Jin, Wei; Yu, Kang-Long

    2013-01-01

    AIM: To investigate whether miRNA-155 (miR-155) dysregulates apical junctional complex (AJC) protein expression in experimental severe acute pancreatitis (SAP). METHODS: Twenty-four male BALB/c mice were randomly assigned to two groups: the SAP group (n = 12) receiving sequential intraperitoneal injection of 50 µg/kg caerulein and 10 mg/kg lipopolysaccharide over 6 h, and the control group (n = 12) receiving intraperitoneal injection of normal saline. Animals were sacrificed 3 h following the last injection for collection of blood samples and pancreas and distal ileal segment specimens. Routine pancreas and intestine histology was used to assess SAP pathology and intestinal epithelial barrier damage. Levels of serum amylase, diamine oxidase (DAO), and tumor necrosis factor (TNF)-α were determined using commercial kits. Total RNA samples were isolated from intestinal epithelial specimens and reversely transcribed into cDNA. miR-155 and RhoA mRNA expression profiles were determined using quantitative real-time polymerase chain reaction. Target genes for miR-155 were predicted using the miRTarBase database, RNA22 and PicTar computational methods. Western blotting was performed to quantitate the protein expression levels of the target gene RhoA, as well as zonula occludens (ZO)-1 and E-cadherin, two AJC component proteins. RESULTS: Intraperitoneal injection of caerulein and lipopolysaccharide successfully induced experimental acute pancreatic damage (SAP vs control, 10.0 ± 2.0 vs 3.2 ± 1.2, P < 0.01) and intestinal epithelial barrier damage (3.2 ± 0.7 vs 1.4 ± 0.7, P < 0.01). Levels of serum amylase (21.6 ± 5.1 U/mL vs 14.3 ± 4.2 U/mL, P < 0.01), DAO (21.4 ± 4.1 mg/mL vs 2.6 ± 0.8 mg/mL, P < 0.01), and TNF-α (61.0 ± 15.1 ng/mL vs 42.9 ± 13.9 ng/mL, P < 0.01) increased significantly in SAP mice compared to those in control mice. miR-155 was significantly overexpressed in SAP intestinal epithelia (1.94 ± 0.50 fold vs 1.03 ± 0.23 fold, P < 0.01), and Rho

  14. Cigarette smoking reprograms apical junctional complex molecular architecture in the human airway epithelium in vivo.

    PubMed

    Shaykhiev, Renat; Otaki, Fouad; Bonsu, Prince; Dang, David T; Teater, Matthew; Strulovici-Barel, Yael; Salit, Jacqueline; Harvey, Ben-Gary; Crystal, Ronald G

    2011-03-01

    The apical junctional complex (AJC), composed of tight and adherens junctions, maintains epithelial barrier function. Since cigarette smoking and chronic obstructive pulmonary disease (COPD), the major smoking-induced disease, are associated with increased lung epithelial permeability, we hypothesized that smoking alters the transcriptional program regulating airway epithelial AJC integrity. Transcriptome analysis revealed global down-regulation of physiological AJC gene expression in the airway epithelium of healthy smokers (n = 59) compared to nonsmokers (n = 53) in association with changes in canonical epithelial differentiation pathways such as PTEN signaling accompanied by induction of cancer-related AJC components. The overall expression of AJC-related genes was further decreased in COPD smokers (n = 23). Exposure of airway epithelial cells to cigarette smoke extract in vitro resulted in down-regulation of several AJC genes paralleled by decreased transepithelial resistance. Thus, cigarette smoking induces transcriptional reprogramming of airway epithelial AJC architecture from its physiological pattern necessary for barrier function toward a disease-associated molecular phenotype.

  15. Cigarette smoke-induced disruption of bronchial epithelial tight junctions is prevented by transforming growth factor-β.

    PubMed

    Schamberger, Andrea C; Mise, Nikica; Jia, Jie; Genoyer, Emmanuelle; Yildirim, Ali Ö; Meiners, Silke; Eickelberg, Oliver

    2014-06-01

    The airway epithelium constitutes an essential immunological and cytoprotective barrier to inhaled insults, such as cigarette smoke, environmental particles, or viruses. Although bronchial epithelial integrity is crucial for airway homeostasis, defective epithelial barrier function contributes to chronic obstructive pulmonary disease (COPD). Tight junctions at the apical side of epithelial cell-cell contacts determine epithelial permeability. Cigarette smoke exposure, the major risk factor for COPD, is suggested to impair tight junction integrity; however, detailed mechanisms thereof remain elusive. We investigated whether cigarette smoke extract (CSE) and transforming growth factor (TGF)-β1 affected tight junction integrity. Exposure of human bronchial epithelial cells (16HBE14o(-)) and differentiated primary human bronchial epithelial cells (pHBECs) to CSE significantly disrupted tight junction integrity and barrier function. Specifically, CSE decreased transepithelial electrical resistance (TEER) and tight junction-associated protein levels. Zonula occludens (ZO)-1 and ZO-2 protein levels were significantly reduced and dislocated from the cell membrane, as observed by fractionation and immunofluorescence analysis. These findings were reproduced in isolated bronchi exposed to CSE ex vivo, as detected by real-time quantitative reverse-transcriptase PCR and immunohistochemistry. Combined treatment of 16HBE14o(-) cells or pHBECs with CSE and TGF-β1 restored ZO-1 and ZO-2 levels. TGF-β1 cotreatment restored membrane localization of ZO-1 and ZO-2 protein and prevented CSE-mediated TEER decrease. In conclusion, CSE led to the disruption of tight junctions of human bronchial epithelial cells, and TGF-β1 counteracted this CSE-induced effect. Thus, TGF-β1 may serve as a protective factor for bronchial epithelial cell homeostasis in diseases such as COPD.

  16. Reciprocal influence of connexins and apical junction proteins on their expressions and functions

    PubMed Central

    Derangeon, Mickaël; Spray, David C.; Bourmeyster, Nicolas; Sarrouilhe, Denis; Hervé, Jean-Claude

    2009-01-01

    Membranes of adjacent cells form intercellular junctional complexes to mechanically anchor neighbour cells (anchoring junctions), to seal the paracellular space and to prevent diffusion of integral proteins within the plasma membrane (tight junctions) and to allow cell-to-cell diffusion of small ions and molecules (gap junctions). These different types of specialised plasma membrane microdomains, sharing common adaptor molecules, particularly zonula occludens proteins, frequently present intermingled relationships where the different proteins co-assemble into macromolecular complexes and their expressions are co-ordinately regulated. Proteins forming gap junction channels (connexins, particularly) and proteins fulfilling cell attachment or forming tight junction strands mutually influence expression and functions of one another. PMID:19046940

  17. Mechanism of IFN-γ-induced Endocytosis of Tight Junction Proteins: Myosin II-dependent Vacuolarization of the Apical Plasma Membrane

    PubMed Central

    Utech, Markus; Ivanov, Andrei I.; Samarin, Stanislav N.; Bruewer, Matthias; Turner, Jerrold R.; Mrsny, Randall J.; Parkos, Charles A.; Nusrat, Asma

    2005-01-01

    Disruption of epithelial barrier by proinflammatory cytokines such as IFN-γ represents a major pathophysiological consequence of intestinal inflammation. We have previously shown that IFN-γ increases paracellular permeability in model T84 epithelial cells by inducing endocytosis of tight junction (TJ) proteins occludin, JAM-A, and claudin-1. The present study was designed to dissect mechanisms of IFN-γ-induced endocytosis of epithelial TJ proteins. IFN-γ treatment of T84 cells resulted in internalization of TJ proteins into large actin-coated vacuoles that originated from the apical plasma membrane and resembled the vacuolar apical compartment (VAC) previously observed in epithelial cells that lose cell polarity. The IFN-γ dependent formation of VACs required ATPase activity of a myosin II motor but was not dependent on rapid turnover of F-actin. In addition, activated myosin II was observed to colocalize with VACs after IFN-γ exposure. Pharmacological analyses revealed that formation of VACs and endocytosis of TJ proteins was mediated by Rho-associated kinase (ROCK) but not myosin light chain kinase (MLCK). Furthermore, IFN-γ treatment resulted in activation of Rho GTPase and induced expressional up-regulation of ROCK. These results, for the first time, suggest that IFN-γ induces endocytosis of epithelial TJ proteins via RhoA/ROCK-mediated, myosin II-dependent formation of VACs. PMID:16055505

  18. Tight Junction Disruption Induced by Type 3 Secretion System Effectors Injected by Enteropathogenic and Enterohemorrhagic Escherichia coli

    PubMed Central

    Ugalde-Silva, Paul; Gonzalez-Lugo, Octavio; Navarro-Garcia, Fernando

    2016-01-01

    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. PMID:27606286

  19. Endocytosis of Epithelial Apical Junctional Proteins by a Clathrin-mediated Pathway into a Unique Storage Compartment

    PubMed Central

    Ivanov, Andrei I.; Nusrat, Asma; Parkos, Charles A.

    2004-01-01

    The adherens junction (AJ) and tight junction (TJ) are key regulators of epithelial polarity and barrier function. Loss of epithelial phenotype is accompanied by endocytosis of AJs and TJs via unknown mechanisms. Using a model of calcium depletion, we defined the pathway of internalization of AJ and TJ proteins (E-cadherin, p120 and β-catenins, occludin, JAM-1, claudins 1 and 4, and ZO-1) in T84 epithelial cells. Proteinase protection assay and immunocytochemistry revealed orchestrated internalization of AJs and TJs into a subapical cytoplasmic compartment. Disruption of caveolae/lipid rafts did not prevent endocytosis, nor did caveolin-1 colocalize with internalized junctional proteins. Furthermore, AJ and TJ proteins did not colocalize with the macropinocytosis marker dextran. Inhibitors of clathrin-mediated endocytosis blocked internalization of AJs and TJs, and junctional proteins colocalized with clathrin and α-adaptin. AJ and TJ proteins were observed to enter early endosomes followed by movement to organelles that stained with syntaxin-4 but not with markers of late and recycling endosomes, lysosomes, or Golgi. These results indicate that endocytosis of junctional proteins is a clathrin-mediated process leading into a unique storage compartment. Such mechanisms may mediate the disruption of intercellular contacts during normal tissue remodeling and in pathology. PMID:14528017

  20. Disruption of MDCK cell tight junctions by the free-living amoeba Naegleria fowleri.

    PubMed

    Shibayama, Mineko; Martínez-Castillo, Moisés; Silva-Olivares, Angélica; Galindo-Gómez, Silvia; Navarro-García, Fernando; Escobar-Herrera, Jaime; Sabanero, Myrna; Tsutsumi, Víctor; Serrano-Luna, Jesús

    2013-02-01

    Naegleria fowleri is the aetiological agent of primary amoebic meningoencephalitis. This parasite invades its host by penetrating the olfactory mucosa. However, the mechanism of epithelium penetration is not well understood. In the present study, we evaluated the effect of N. fowleri trophozoites and the non-pathogenic Naegleria gruberi on Madin-Darby canine kidney (MDCK) tight junction proteins, including claudin-1, occludin and ZO-1, as well as on the actin cytoskeleton. Trophozoites from each of the free-living amoeba species were co-cultured with MDCK cells in a 1 : 1 ratio for 1, 3, 6 or 10 h. Light microscopy revealed that N. fowleri caused morphological changes as early as 3 h post-infection in an epithelial MDCK monolayer. Confocal microscopy analysis revealed that after 10 h of co-culture, N. fowleri trophozoites induced epithelial cell damage, which was characterized by changes in the actin apical ring and disruption of the ZO-1 and claudin-1 proteins but not occludin. Western blot assays revealed gradual degradation of ZO-1 and claudin-1 as early as 3 h post-infection. Likewise, there was a drop in transepithelial electrical resistance that resulted in increased epithelial permeability and facilitated the invasion of N. fowleri trophozoites by a paracellular route. In contrast, N. gruberi did not induce alterations in MDCK cells even at 10 h post-infection. Based on these results, we suggest that N. fowleri trophozoites disrupt epithelial monolayers, which could enable their penetration of the olfactory epithelium and subsequent invasion of the central nervous system.

  1. Localization and Function of Pals1-associated Tight Junction Protein in Drosophila Is Regulated by Two Distinct Apical Complexes.

    PubMed

    Sen, Arnab; Sun, Rui; Krahn, Michael P

    2015-05-22

    The transmembrane protein Crumbs (Crb) and its intracellular adaptor protein Pals1 (Stardust, Sdt in Drosophila) play a crucial role in the establishment and maintenance of apical-basal polarity in epithelial cells in various organisms. In contrast, the multiple PDZ domain-containing protein Pals1-associated tight junction protein (PATJ), which has been described to form a complex with Crb/Sdt, is not essential for apical basal polarity or for the stability of the Crb/Sdt complex in the Drosophila epidermis. Here we show that, in the embryonic epidermis, Sdt is essential for the correct subcellular localization of PATJ in differentiated epithelial cells but not during cellularization. Consistently, the L27 domain of PATJ is crucial for the correct localization and function of the protein. Our data further indicate that the four PDZ domains of PATJ function, to a large extent, in redundancy, regulating the function of the protein. Interestingly, the PATJ-Sdt heterodimer is not only recruited to the apical cell-cell contacts by binding to Crb but depends on functional Bazooka (Baz). However, biochemical experiments show that PATJ associates with both complexes, the Baz-Sdt and the Crb-Sdt complex, in the mature epithelium of the embryonic epidermis, suggesting a role of these two complexes for the function of PATJ during the development of Drosophila.

  2. Apical electrolyte concentration modulates barrier function and tight junction protein localization in bovine mammary epithelium.

    PubMed

    Quesnell, Rebecca R; Erickson, Jamie; Schultz, Bruce D

    2007-01-01

    In vitro mammary epithelial cell models typically fail to form a consistently tight barrier that can effectively separate blood from milk. Our hypothesis was that mammary epithelial barrier function would be affected by changes in luminal ion concentration and inflammatory cytokines. Bovine mammary epithelial (BME-UV cell line) cells were grown to confluence on permeable supports with a standard basolateral medium and either high-electrolyte (H-elec) or low-electrolyte (L-elec) apical medium for 14 days. Apical media were changed to/from H-elec medium at predetermined times prior to assay. Transepithelial electrical resistance (R(te)) was highest in monolayers continuously exposed to apical L-elec. A time-dependent decline in R(te) began within 24 h of H-elec medium exposure. Change from H-elec medium to L-elec medium time-dependently increased R(te). Permeation by FITC-conjugated dextran was elevated across monolayers exposed to H-elec, suggesting compromise of a paracellular pathway. Significant alteration in occludin distribution was evident, concomitant with the changes in R(te), although total occludin was unchanged. Neither substitution of Na(+) with N-methyl-d-glucosamine (NMDG(+)) nor pharmacological inhibition of transcellular Na(+) transport pathways abrogated the effects of apical H-elec medium on R(te). Tumor necrosis factor alpha, but not interleukin-1beta nor interleukin-6, in the apical compartment caused a significant decrease in R(te) within 8 h. These results indicate that mammary epithelium is a dynamic barrier whose cell-cell contacts are acutely modulated by cytokines and luminal electrolyte environment. Results not only demonstrate that BME-UV cells are a model system representative of mammary epithelium but also provide critical information that can be applied to other mammary model systems to improve their physiological relevance.

  3. Crucial Role of Rapgef2 and Rapgef6, a Family of Guanine Nucleotide Exchange Factors for Rap1 Small GTPase, in Formation of Apical Surface Adherens Junctions and Neural Progenitor Development in the Mouse Cerebral Cortex123

    PubMed Central

    Maeta, Kazuhiro; Edamatsu, Hironori; Nishihara, Kaori; Ikutomo, Junji; Bilasy, Shymaa E.

    2016-01-01

    Abstract Cerebral neocortex development in mammals requires highly orchestrated events involving proliferation, differentiation, and migration of neural progenitors and neurons. Rapgef2 and Rapgef6 constitute a unique family of guanine nucleotide exchange factors for Rap1 small GTPase, which is known to play crucial roles in migration of postmitotic neurons. We previously reported that conditional knockout of Rapgef2 in dorsal telencephalon (Rapgef2-cKO) resulted in the formation of an ectopic cortical mass (ECM) resembling that of subcortical band heterotopia. Here we show that double knockout of Rapgef6 in Rapgef2-cKO mice (Rapgef2/6-dKO) results in marked enlargement of the ECM. While Rapgef2-cKO affects late-born neurons only, Rapgef2/6-dKO affects both early-born and late-born neurons. The Rapgef2-cKO cortex at embryonic day (E) 15.5, and the Rapgef2/6-dKO cortex at E13.5 and E15.5 show disruption of the adherens junctions (AJs) on the apical surface, detachment of radial glial cells (RGCs) from the apical surface and disorganization of the radial glial fiber system, which are accompanied by aberrant distribution of RGCs and intermediate progenitors, normally located in the ventricular zone and the subventricular zone, respectively, over the entire cerebral cortex. Moreover, intrauterine transduction of Cre recombinase into the Rapgef2flox/flox brains also results in the apical surface AJ disruption and the RGC detachment from the apical surface, both of which are effectively suppressed by cotransduction of the constitutively active Rap1 mutant Rap1G12V. These results demonstrate a cell-autonomous role of the Rapgef2/6-Rap1 pathway in maintaining the apical surface AJ structures, which is necessary for the proper development of neural progenitor cells. PMID:27390776

  4. Irinotecan disrupts tight junction proteins within the gut

    PubMed Central

    Wardill, Hannah R; Bowen, Joanne M; Al-Dasooqi, Noor; Sultani, Masooma; Bateman, Emma; Stansborough, Romany; Shirren, Joseph; Gibson, Rachel J

    2014-01-01

    Chemotherapy for cancer causes significant gut toxicity, leading to severe clinical manifestations and an increased economic burden. Despite much research, many of the underlying mechanisms remain poorly understood hindering effective treatment options. Recently there has been renewed interest in the role tight junctions play in the pathogenesis of chemotherapy-induced gut toxicity. To delineate the underlying mechanisms of chemotherapy-induced gut toxicity, this study aimed to quantify the molecular changes in key tight junction proteins, ZO-1, claudin-1, and occludin, using a well-established preclinical model of gut toxicity. Female tumor-bearing dark agouti rats received irinotecan or vehicle control and were assessed for validated parameters of gut toxicity including diarrhea and weight loss. Rats were killed at 6, 24, 48, 72, 96, and 120 h post-chemotherapy. Tight junction protein and mRNA expression in the small and large intestines were assessed using semi-quantitative immunohistochemistry and RT-PCR. Significant changes in protein expression of tight junction proteins were seen in both the jejunum and colon, correlating with key histological changes and clinical features. mRNA levels of claudin-1 were significantly decreased early after irinotecan in the small and large intestines. ZO-1 and occludin mRNA levels remained stable across the time-course of gut toxicity. Findings strongly suggest irinotecan causes tight junction defects which lead to mucosal barrier dysfunction and the development of diarrhea. Detailed research is now warranted to investigate posttranslational regulation of tight junction proteins to delineate the underlying pathophysiology of gut toxicity and identify future therapeutic targets. PMID:24316664

  5. Expression of apical junction complex proteins in colorectal mucosa of miniature dachshunds with inflammatory colorectal polyps

    PubMed Central

    YOKOYAMA, Nozomu; OHTA, Hiroshi; KAGAWA, Yumiko; LEELA-ARPORN, Rommaneeya; DERMLIM, Angkhana; NISA, Khoirun; MORITA, Tomoya; OSUGA, Tatsuyuki; SASAKI, Noboru; MORISHITA, Keitaro; NAKAMURA, Kensuke; TAKIGUCHI, Mitsuyoshi

    2017-01-01

    We examine the expression of tight junction and adherence junction proteins in the colorectal mucosa of miniature dachshunds (MDs) with inflammatory colorectal polyps (ICRPs). Colorectal mucosa samples were endoscopically obtained from 8 MDs with ICRPs and 8 control dogs for immunoblotting. Paraffin-embedded tissues of surgically resected inflamed lesions from another 5 MDs with ICRPs and full-thickness colorectal specimens from 5 healthy beagles were obtained for immunohistochemistry. The expression patterns of claudin-1, -2, -3, -4, -5, -7 and -8, E-cadherin and β-catenin were analyzed in the non-inflamed mucosa and inflamed mucosa of ICRPs and colorectal mucosa of control dogs by immunoblotting. The localization of these proteins in the inflamed lesions was analyzed by immunohistochemistry. The expressions of each of claudin, E-cadherin and β-catenin were not significantly different between control dogs and non-inflamed colonic mucosa from MDs with ICRPs. In contrast, only E-cadherin and β-catenin were detected in the inflamed lesions of MDs with ICRPs. By immunohistochemistry, claudin-2, -3, -4, -5 and -7, E-cadherin and β-catenin were expressed in the colorectal epithelium within the inflamed mucosa, but not in granulation tissue. Distributions of claudin-2, -3, -4, -5, and -7, E-cadherin and β-catenin in the colonic epithelium were not different between MDs with ICRPs and control dogs. These results indicated that no significant alteration was detected in several tight junction or adherence junction proteins expression in the colorectal epithelium of ICRPs. PMID:28090006

  6. Atelectrauma disrupts pulmonary epithelial barrier integrity and alters the distribution of tight junction proteins ZO-1 and claudin 4

    PubMed Central

    Jacob, Anne-Marie

    2012-01-01

    Mechanical ventilation inevitably exposes the delicate tissues of the airways and alveoli to abnormal mechanical stresses that can induce pulmonary edema and exacerbate conditions such as acute respiratory distress syndrome. The goal of our research is to characterize the cellular trauma caused by the transient abnormal fluid mechanical stresses that arise when air is forced into a liquid-occluded airway (i.e., atelectrauma). Using a fluid-filled, parallel-plate flow chamber to model the “airway reopening” process, our in vitro study examined consequent increases in pulmonary epithelial plasma membrane rupture, paracellular permeability, and disruption of the tight junction (TJ) proteins zonula occludens-1 and claudin-4. Computational analysis predicts the normal and tangential surface stresses that develop between the basolateral epithelial membrane and underlying substrate due to the interfacial stresses acting on the apical cell membrane. These simulations demonstrate that decreasing the velocity of reopening causes a significant increase in basolateral surface stresses, particularly in the region between neighboring cells where TJs concentrate. Likewise, pulmonary epithelial wounding, paracellular permeability, and TJ protein disruption were significantly greater following slower reopening. This study thus demonstrates that maintaining a higher velocity of reopening, which reduces the damaging fluid stresses acting on the airway wall, decreases the mechanical stresses on the basolateral cell surface while protecting cells from plasma membrane rupture and promoting barrier integrity. PMID:22898551

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

    PubMed

    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. 17β-Estradiol Ameliorates Tight Junction Disruption via Repression of MMP Transcription.

    PubMed

    Na, Wonho; Lee, Jee Youn; Kim, Won-Sun; Yune, Tae Young; Ju, Bong-Gun

    2015-09-01

    The blood-brain barrier (BBB) or blood-spinal cord barrier (BSCB) formed by capillary endothelial cells provides a physical wall between the central nervous system (CNS) and circulating blood with highly selective permeability. BBB/BSCB disruption by activation of matrix metalloproteinases (MMPs) has been shown to result in further neurological damage after CNS injury. Recently it has been discovered that estrogen attenuates BBB/BSCB disruption in in vitro and in vivo models. However, the molecular mechanism underlying the estrogen-mediated attenuation of BBB/BSCB disruption has not been elucidated fully. In the present study, we found that 17β-estradiol (E2) suppresses nuclear factor-κB-dependent MMP-1b, MMP-2, MMP-3, MMP-9, MMP-10, and MMP-13 gene activation in microvessel endothelial bEnd.3 cells subjected to oxygen and glucose deprivation/reperfusion injury. E2 induced the recruitment of ERα and nuclear receptor corepressor to the nuclear factor-κB binding site on the MMPs' gene promoters. Consistently, ER antagonist ICI 182.780 showed opposite effects of E2. We further found that E2 attenuates tight junction disruption through the decreased degradation of tight junction proteins in bEnd.3 cells subjected to oxygen and glucose deprivation-reperfusion injury. In addition, E2 suppressed the up-regulation of MMP expression, leading to a decreased BSCB disruption in the injured spinal cord. In conclusion, we discovered the molecular mechanism underlying the protective role of estrogenin BBB/BSCB disruption using an in vitro and in vivo model. Our study suggests that estrogens may provide a potential therapeutic intervention for preserving BBB/BSCB integrity after CNS injury.

  9. Secretion of Alpha-Hemolysin by Escherichia coli Disrupts Tight Junctions in Ulcerative Colitis Patients

    PubMed Central

    Mirsepasi-Lauridsen, Hengameh Chloé; Du, Zhengyu; Struve, Carsten; Charbon, Godefroid; Karczewski, Jurgen; Krogfelt, Karen Angeliki; Petersen, Andreas Munk; Wells, Jerry M

    2016-01-01

    Objectives: The potential of Escherichia coli (E. coli) isolated from inflammatory bowel disease (IBD) patients to damage the integrity of the intestinal epithelium was investigated. Methods: E. coli strains isolated from patients with ulcerative colitis (UC) and healthy controls were tested for virulence capacity by molecular techniques and cytotoxic assays and transepithelial electric resistance (TER). E. coli isolate p19A was selected, and deletion mutants were created for alpha-hemolysin (α-hemolysin) (hly) clusters and cytotoxic necrotizing factor type 1 (cnf1). Probiotic E. coli Nissle and pathogenic E. coli LF82 were used as controls. Results: E. coli strains from patients with active UC completely disrupted epithelial cell tight junctions shortly after inoculation. These strains belong to phylogenetic group B2 and are all α-hemolysin positive. In contrast, probiotic E. coli Nissle, pathogenic E. coli LF82, four E. coli from patients with inactive UC and three E. coli strains from healthy controls did not disrupt tight junctions. E. coli p19A WT as well as cnf1, and single loci of hly mutants from cluster I and II were all able to damage Caco-2 (Heterogeneous human epithelial colorectal adenocarcinoma) cell tight junctions. However, this phenotype was lost in a mutant with knockout (Δ) of both hly loci (P<0.001). Conclusions: UC-associated E. coli producing α-hemolysin can cause rapid loss of tight junction integrity in differentiated Caco-2 cell monolayers. This effect was abolished in a mutant unable to express α-hemolysin. These results suggest that high Hly expression may be a mechanism by which specific strains of E. coli pathobionts can contribute to epithelial barrier dysfunction and pathophysiology of disease in IBD. PMID:26938480

  10. HIV-associated disruption of tight and adherens junctions of oral epithelial cells facilitates HSV-1 infection and spread.

    PubMed

    Sufiawati, Irna; Tugizov, Sharof M

    2014-01-01

    Herpes simplex virus (HSV) types 1 and 2 are the most common opportunistic infections in HIV/AIDS. In these immunocompromised individuals, HSV-1 reactivates and replicates in oral epithelium, leading to oral disorders such as ulcers, gingivitis, and necrotic lesions. Although the increased risk of HSV infection may be mediated in part by HIV-induced immune dysfunction, direct or indirect interactions of HIV and HSV at the molecular level may also play a role. In this report we show that prolonged interaction of the HIV proteins tat and gp120 and cell-free HIV virions with polarized oral epithelial cells leads to disruption of tight and adherens junctions of epithelial cells through the mitogen-activated protein kinase signaling pathway. HIV-induced disruption of oral epithelial junctions facilitates HSV-1 paracellular spread between the epithelial cells. Furthermore, HIV-associated disruption of adherens junctions exposes sequestered nectin-1, an adhesion protein and critical receptor for HSV envelope glycoprotein D (gD). Exposure of nectin-1 facilitates binding of HSV-1 gD, which substantially increases HSV-1 infection of epithelial cells with disrupted junctions over that of cells with intact junctions. Exposed nectin-1 from disrupted adherens junctions also increases the cell-to-cell spread of HSV-1 from infected to uninfected oral epithelial cells. Antibodies to nectin-1 and HSV-1 gD substantially reduce HSV-1 infection and cell-to-cell spread, indicating that HIV-promoted HSV infection and spread are mediated by the interaction of HSV gD with HIV-exposed nectin-1. Our data suggest that HIV-associated disruption of oral epithelial junctions may potentiate HSV-1 infection and its paracellular and cell-to-cell spread within the oral mucosal epithelium. This could be one of the possible mechanisms of rapid development of HSV-associated oral lesions in HIV-infected individuals.

  11. Clostridium difficile Toxins Disrupt Epithelial Barrier Function by Altering Membrane Microdomain Localization of Tight Junction Proteins

    PubMed Central

    Nusrat, A.; von Eichel-Streiber, C.; Turner, J. R.; Verkade, P.; Madara, J. L.; Parkos, C. A.

    2001-01-01

    The anaerobic bacterium Clostridium difficile is the etiologic agent of pseudomembranous colitis. C. difficile toxins TcdA and TcdB are UDP-glucosyltransferases that monoglucosylate and thereby inactivate the Rho family of GTPases (W. P. Ciesla, Jr., and D. A. Bobak, J. Biol. Chem. 273:16021–16026, 1998). We utilized purified reference toxins of C. difficile, TcdA-10463 (TcdA) and TcdB-10463 (TcdB), and a model intestinal epithelial cell line to characterize their influence on tight-junction (TJ) organization and hence to analyze the mechanisms by which they contribute to the enhanced paracellular permeability and disease pathophysiology of pseudomembranous colitis. The increase in paracellular permeability induced by TcdA and TcdB was associated with disorganization of apical and basal F-actin. F-actin restructuring was paralleled by dissociation of occludin, ZO-1, and ZO-2 from the lateral TJ membrane without influencing the subjacent adherens junction protein, E-cadherin. In addition, we observed decreased association of actin with the TJ cytoplasmic plaque protein ZO-1. Differential detergent extraction and fractionation in sucrose density gradients revealed TcdB-induced redistribution of occludin and ZO-1 from detergent-insoluble fractions constituting “raft-like” membrane microdomains, suggesting an important role of Rho proteins in maintaining the association of TJ proteins with such microdomains. These toxin-mediated effects on actin and TJ structure provide a mechanism for early events in the pathophysiology of pseudomembranous colitis. PMID:11179295

  12. The Role of Circulating Tight Junction Proteins in Evaluating Blood Brain Barrier Disruption following Intracranial Hemorrhage.

    PubMed

    Jiao, Xiaoyang; He, Ping; Li, Yazhen; Fan, Zhicheng; Si, Mengya; Xie, Qingdong; Chang, Xiaolan; Huang, Dongyang

    2015-01-01

    Brain injury after intracranial hemorrhage (ICH) results in significant morbidity and mortality. Blood brain barrier (BBB) disruption is a hallmark of ICH-induced brain injury; however, data mirroring BBB disruption in human ICH are scarce. The aim of this study was to assess the significance of circulating biomarkers in evaluating BBB disruption after ICH. Twenty-two patients with ICH were recruited in this study. Concentrations of the tight junction proteins (TJs) Claudin-5 (CLDN5), Occludin (OCLN), and zonula occludens 1 (ZO-1) and vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) were measured by using enzyme-linked immunosorbent assay in serum and cerebrospinal fluid (CSF) samples obtained from patients with ICH. The white blood cell (WBC) count in blood and CSF, albumin (ALB) levels in the CSF (ALBCSF), and the BBB ratio were significantly higher in the ICH than in controls (p < 0.05). Significantly higher levels of CLDN5, OCLN, ZO-1, MMP-9, and VEGF in CSF were observed in the ICH group; these biomarkers were also positively associated with BBB ratio (p < 0.05). Our data revealed that circulating TJs could be considered the potential biomarkers reflecting the integrity of the BBB in ICH.

  13. The Role of Circulating Tight Junction Proteins in Evaluating Blood Brain Barrier Disruption following Intracranial Hemorrhage

    PubMed Central

    Jiao, Xiaoyang; He, Ping; Li, Yazhen; Fan, Zhicheng; Si, Mengya; Xie, Qingdong; Chang, Xiaolan; Huang, Dongyang

    2015-01-01

    Brain injury after intracranial hemorrhage (ICH) results in significant morbidity and mortality. Blood brain barrier (BBB) disruption is a hallmark of ICH-induced brain injury; however, data mirroring BBB disruption in human ICH are scarce. The aim of this study was to assess the significance of circulating biomarkers in evaluating BBB disruption after ICH. Twenty-two patients with ICH were recruited in this study. Concentrations of the tight junction proteins (TJs) Claudin-5 (CLDN5), Occludin (OCLN), and zonula occludens 1 (ZO-1) and vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) were measured by using enzyme-linked immunosorbent assay in serum and cerebrospinal fluid (CSF) samples obtained from patients with ICH. The white blood cell (WBC) count in blood and CSF, albumin (ALB) levels in the CSF (ALBCSF), and the BBB ratio were significantly higher in the ICH than in controls (p < 0.05). Significantly higher levels of CLDN5, OCLN, ZO-1, MMP-9, and VEGF in CSF were observed in the ICH group; these biomarkers were also positively associated with BBB ratio (p < 0.05). Our data revealed that circulating TJs could be considered the potential biomarkers reflecting the integrity of the BBB in ICH. PMID:26586924

  14. Calcium Channels and Oxidative Stress Mediate a Synergistic Disruption of Tight Junctions by Ethanol and Acetaldehyde in Caco-2 Cell Monolayers.

    PubMed

    Samak, Geetha; Gangwar, Ruchika; Meena, Avtar S; Rao, Roshan G; Shukla, Pradeep K; Manda, Bhargavi; Narayanan, Damodaran; Jaggar, Jonathan H; Rao, RadhaKrishna

    2016-12-13

    Ethanol is metabolized into acetaldehyde in most tissues. In this study, we investigated the synergistic effect of ethanol and acetaldehyde on the tight junction integrity in Caco-2 cell monolayers. Expression of alcohol dehydrogenase sensitized Caco-2 cells to ethanol-induced tight junction disruption and barrier dysfunction, whereas aldehyde dehydrogenase attenuated acetaldehyde-induced tight junction disruption. Ethanol up to 150 mM did not affect tight junction integrity or barrier function, but it dose-dependently increased acetaldehyde-mediated tight junction disruption and barrier dysfunction. Src kinase and MLCK inhibitors blocked this synergistic effect of ethanol and acetaldehyde on tight junction. Ethanol and acetaldehyde caused a rapid and synergistic elevation of intracellular calcium. Calcium depletion by BAPTA or Ca(2+)-free medium blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. Diltiazem and selective knockdown of TRPV6 or CaV1.3 channels, by shRNA blocked ethanol and acetaldehyde-induced tight junction disruption and barrier dysfunction. Ethanol and acetaldehyde induced a rapid and synergistic increase in reactive oxygen species by a calcium-dependent mechanism. N-acetyl-L-cysteine and cyclosporine A, blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. These results demonstrate that ethanol and acetaldehyde synergistically disrupt tight junctions by a mechanism involving calcium, oxidative stress, Src kinase and MLCK.

  15. Calcium Channels and Oxidative Stress Mediate a Synergistic Disruption of Tight Junctions by Ethanol and Acetaldehyde in Caco-2 Cell Monolayers

    PubMed Central

    Samak, Geetha; Gangwar, Ruchika; Meena, Avtar S.; Rao, Roshan G.; Shukla, Pradeep K.; Manda, Bhargavi; Narayanan, Damodaran; Jaggar, Jonathan H.; Rao, RadhaKrishna

    2016-01-01

    Ethanol is metabolized into acetaldehyde in most tissues. In this study, we investigated the synergistic effect of ethanol and acetaldehyde on the tight junction integrity in Caco-2 cell monolayers. Expression of alcohol dehydrogenase sensitized Caco-2 cells to ethanol-induced tight junction disruption and barrier dysfunction, whereas aldehyde dehydrogenase attenuated acetaldehyde-induced tight junction disruption. Ethanol up to 150 mM did not affect tight junction integrity or barrier function, but it dose-dependently increased acetaldehyde-mediated tight junction disruption and barrier dysfunction. Src kinase and MLCK inhibitors blocked this synergistic effect of ethanol and acetaldehyde on tight junction. Ethanol and acetaldehyde caused a rapid and synergistic elevation of intracellular calcium. Calcium depletion by BAPTA or Ca2+-free medium blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. Diltiazem and selective knockdown of TRPV6 or CaV1.3 channels, by shRNA blocked ethanol and acetaldehyde-induced tight junction disruption and barrier dysfunction. Ethanol and acetaldehyde induced a rapid and synergistic increase in reactive oxygen species by a calcium-dependent mechanism. N-acetyl-L-cysteine and cyclosporine A, blocked ethanol and acetaldehyde-induced barrier dysfunction and tight junction disruption. These results demonstrate that ethanol and acetaldehyde synergistically disrupt tight junctions by a mechanism involving calcium, oxidative stress, Src kinase and MLCK. PMID:27958326

  16. Calcium/Ask1/MKK7/JNK2/c-Src signalling cascade mediates disruption of intestinal epithelial tight junctions by dextran sulfate sodium.

    PubMed

    Samak, Geetha; Chaudhry, Kamaljit K; Gangwar, Ruchika; Narayanan, Damodaran; Jaggar, Jonathan H; Rao, RadhaKrishna

    2015-02-01

    Disruption of intestinal epithelial tight junctions is an important event in the pathogenesis of ulcerative colitis. Dextran sodium sulfate (DSS) induces colitis in mice with symptoms similar to ulcerative colitis. However, the mechanism of DSS-induced colitis is unknown. We investigated the mechanism of DSS-induced disruption of intestinal epithelial tight junctions and barrier dysfunction in Caco-2 cell monolayers in vitro and mouse colon in vivo. DSS treatment resulted in disruption of tight junctions, adherens junctions and actin cytoskeleton leading to barrier dysfunction in Caco-2 cell monolayers. DSS induced a rapid activation of c-Jun N-terminal kinase (JNK), and the inhibition or knockdown of JNK2 attenuated DSS-induced tight junction disruption and barrier dysfunction. In mice, DSS administration for 4 days caused redistribution of tight junction and adherens junction proteins from the epithelial junctions, which was blocked by JNK inhibitor. In Caco-2 cell monolayers, DSS increased intracellular Ca(2+) concentration, and depletion of intracellular Ca(2+) by 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid tetrakis(acetoxymethyl ester) (BAPTA/AM) or thapsigargin attenuated DSS-induced JNK activation, tight junction disruption and barrier dysfunction. Knockdown of apoptosis signal-regulated kinase 1 (Ask1) or MKK7 blocked DSS-induced tight junction disruption and barrier dysfunction. DSS activated c-Src by a Ca2+ and JNK-dependent mechanism. Inhibition of Src kinase activity or knockdown of c-Src blocked DSS-induced tight junction disruption and barrier dysfunction. DSS increased tyrosine phosphorylation of occludin, zonula occludens-1 (ZO-1), E-cadherin and β-catenin. SP600125 abrogated DSS-induced tyrosine phosphorylation of junctional proteins. Recombinant JNK2 induced threonine phosphorylation and auto-phosphorylation of c-Src. The present study demonstrates that Ca(2+)/Ask1/MKK7/JNK2/cSrc signalling cascade mediates DSS-induced tight

  17. Oncogenic extracellular HSP70 disrupts the gap-junctional coupling between capillary cells

    PubMed Central

    Thuringer, Dominique; Berthenet, Kevin; Cronier, Laurent; Jego, Gaetan; Solary, Eric; Garrido, Carmen

    2015-01-01

    High levels of circulating heat shock protein 70 (HSP70) are detected in many cancers. In order to explore the effects of extracellular HSP70 on human microvascular endothelial cells (HMEC), we initially used gap-FRAP technique. Extracellular human HSP70 (rhHSP70), but not rhHSP27, blocks the gap-junction intercellular communication (GJIC) between HMEC, disrupts the structural integrity of HMEC junction plaques, and decreases connexin43 (Cx43) expression, which correlates with the phosphorylation of Cx43 serine residues. Further exploration of these effects identified a rapid transactivation of the Epidermal Growth Factor Receptor in a Toll-Like Receptor 4-dependent manner, preceding its internalization. In turn, cytosolic Ca2+ oscillations are generated. Both GJIC blockade and Ca2+ mobilization partially depend on ATP release through Cx43 and pannexin (Panx-1) channels, as demonstrated by blocking activity or expression of channels, and inactivating extracellular ATP. By monitoring dye-spreading into adjacent cells, we show that HSP70 released from human monocytes in response to macrophage colony-stimulating factor, prevents the formation of GJIC between monocytes and HMEC. Therapeutic manipulation of this pathway could be of interest in inflammatory and tumor growth. PMID:25868858

  18. Diminishing parochialism in intergroup conflict by disrupting the right temporo-parietal junction.

    PubMed

    Baumgartner, Thomas; Schiller, Bastian; Rieskamp, Jörg; Gianotti, Lorena R R; Knoch, Daria

    2014-05-01

    Individuals react to violation of social norms by outgroup members differently than to transgressions of those same norms by ingroup members: namely outgroup perpetrators are punished much more harshly than ingroup perpetrators. This parochial punishment pattern has been observed and extensively studied in social psychology and behavioral economics. Despite progress in recent years, however, little is known about the neural underpinnings of this intergroup bias. Here, we demonstrate by means of transcranial magnetic stimulation (TMS) that the transient disruption of the right, but not the left temporo-parietal junction (TPJ), reduces parochial punishment in a third-party punishment paradigm with real social groups. Moreover, we show that this observed TMS effect on parochial punishment is mediated by a classical punishment motive, i.e. retaliation. Finally, our data suggests that a change in perspective-taking might be the underlying mechanism that explains the impact of right TPJ disruption on retaliation motivation and parochial punishment. These findings provide the first causal evidence that the right TPJ plays a pivotal role in the implementation of parochial behaviors.

  19. Acetaldehyde disrupts tight junctions in Caco-2 cell monolayers by a protein phosphatase 2A-dependent mechanism.

    PubMed

    Dunagan, Mitzi; Chaudhry, Kamaljit; Samak, Geetha; Rao, R K

    2012-12-15

    Acetaldehyde is accumulated at high concentrations in the colonic lumen following ethanol administration. Previous studies demonstrated that acetaldehyde disrupts intestinal epithelial tight junctions and increases paracellular permeability. In the present study, we investigated the role of PP2A in the acetaldehyde-induced disruption of intestinal epithelial tight junctions. Caco-2 cell monolayers were exposed to 200-600 μM acetaldehyde for varying times, and the epithelial barrier function was evaluated by measuring transepithelial electrical resistance and inulin permeability. Acetaldehyde treatment resulted in a time-dependent increase in inulin permeability and redistribution of occludin and ZO-1 from the intercellular junctions. Treatment of cells with fostriecin (a PP2A-selective inhibitor) or knockdown of PP2A by siRNA blocked acetaldehyde-induced increase in inulin permeability and redistribution of occludin and ZO-1. The effects of fostriecin and acetaldehyde were confirmed in mouse intestine ex vivo. Acetaldehyde-induced tight junction disruption and barrier dysfunction were also attenuated by a PP2A-specific inhibitory peptide, TPDYFL. Coimmunoprecipitation studies showed that acetaldehyde increased the interaction of PP2A with occludin and induced dephosphorylation of occludin on threonine residues. Fostriecin and TPDYFL significantly reduced acetaldehyde-induced threonine dephosphorylation of occludin. Acetaldehyde failed to change the level of the methylated form of PP2A-C subunit. However, genistein (a tyrosine kinase inhibitor) blocked acetaldehyde-induced association of PP2A with occludin and threonine dephosphorylation of occludin. These results demonstrate that acetaldehyde-induced disruption of tight junctions is mediated by PP2A translocation to tight junctions and dephosphorylation of occludin on threonine residues.

  20. 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

    PubMed Central

    2010-01-01

    that arecoline potentially disrupts cell-cell interactions mediated by ZO-1, which may play a role in arecoline-mediated carcinogenesis. Furthermore, our study has uncovered the dependency of ZO-1 localization and expression on HER2 expression, which has therefore established a new cellular link between HER2 mediated signaling and apical junction formation involving ZO-1. PMID:20604955

  1. Targeted Disruption of Core 1 β1,3-galactosyltransferase (C1galt1) Induces Apical Endocytic Trafficking in Human Corneal Keratinocytes

    PubMed Central

    Guzman-Aranguez, Ana; Woodward, Ashley M.; Pintor, Jesús; Argüeso, Pablo

    2012-01-01

    Background Exposed mucosal surfaces limit constitutive endocytosis under physiological conditions to prevent uptake of macromolecules and pathogens and, therefore, cellular damage. It is now accepted that cell surface mucins, a group of high molecular weight glycoproteins on the epithelial glycocalyx, defined by their extensive O-glycosylation, play a major role in maintaining barrier function in these surfaces, but the precise mechanisms are unclear. Methodology/Principal Findings In this work, we utilized a stable tetracycline-inducible RNA interfering system targeting the core 1 ß1,3-galactosyltransferase (C1galt1 or T-synthase), a critical galactosyltransferase required for the synthesis of core 1 O-glycans, to explore the role of mucin-type carbohydrates in apical endocytic trafficking in human corneal keratinocytes. Using cell surface biotinylation and subcellular fractionation, we found increased accumulation of plasma membrane protein in endosomes after C1galt1 depletion. Confocal laser scanning microscopy and fluorometry revealed increased translocation of negatively charged fluorescent nanospheres after C1galt1 knockdown sustained by an active transport process and largely independent of apical intercellular junctions. Internalization of nanospheres could be blocked by dynasore, nocodazole, chlorpromazine, and hyperosmotic sucrose, suggesting a mechanism for clathrin-coated pit budding and vesicular trafficking. This possibility was supported by experiments showing nanosphere colocalization with clathrin heavy chain in the cytoplasm. Conclusions/Significance Together, the data suggest that core 1 O-glycans contribute to maintenance of apical barrier function on exposed mucosal surfaces by preventing clathrin-mediated endocytosis. PMID:22574202

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

    PubMed

    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 < 0.05). Both 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

  3. Mild hypothermia alleviates brain oedema and blood-brain barrier disruption by attenuating tight junction and adherens junction breakdown in a swine model of cardiopulmonary resuscitation

    PubMed Central

    Li, Jiebin; Li, Chunsheng; Yuan, Wei; Wu, Junyuan; Li, Jie; Li, Zhenhua; Zhao, Yongzhen

    2017-01-01

    Mild hypothermia improves survival and neurological recovery after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). However, the mechanism underlying this phenomenon is not fully elucidated. The aim of this study was to determine whether mild hypothermia alleviates early blood–brain barrier (BBB) disruption. We investigated the effects of mild hypothermia on neurologic outcome, survival rate, brain water content, BBB permeability and changes in tight junctions (TJs) and adherens junctions (AJs) after CA and CPR. Pigs were subjected to 8 min of untreated ventricular fibrillation followed by CPR. Mild hypothermia (33°C) was intravascularly induced and maintained at this temperature for 12 h, followed by active rewarming. Mild hypothermia significantly reduced cortical water content, decreased BBB permeability and attenuated TJ ultrastructural and basement membrane breakdown in brain cortical microvessels. Mild hypothermia also attenuated the CPR-induced decreases in TJ (occludin, claudin-5, ZO-1) and AJ (VE-cadherin) protein and mRNA expression. Furthermore, mild hypothermia decreased the CA- and CPR-induced increases in matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) expression and increased angiogenin-1 (Ang-1) expression. Our findings suggest that mild hypothermia attenuates the CA- and resuscitation-induced early brain oedema and BBB disruption, and this improvement might be at least partially associated with attenuation of the breakdown of TJ and AJ, suppression of MMP-9 and VEGF expression, and upregulation of Ang-1 expression. PMID:28355299

  4. Calcium-mediated oxidative stress: a common mechanism in tight junction disruption by different types of cellular stress.

    PubMed

    Gangwar, Ruchika; Meena, Avtar S; Shukla, Pradeep K; Nagaraja, Archana S; Dorniak, Piotr L; Pallikuth, Sandeep; Waters, Christopher M; Sood, Anil; Rao, RadhaKrishna

    2017-02-20

    The role of reactive oxygen species (ROS) in osmotic stress, dextran sulfate sodium (DSS) and cyclic stretch-induced tight junction (TJ) disruption was investigated in Caco-2 cell monolayers in vitro and restraint stress-induced barrier dysfunction in mouse colon in vivo Live cell imaging showed that osmotic stress, cyclic stretch and DSS triggered rapid production of ROS in Caco-2 cell monolayers, which was blocked by depletion of intracellular Ca(2+) by 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. Knockdown of CaV1.3 or TRPV6 channels blocked osmotic stress and DSS-induced ROS production and attenuated TJ disruption and barrier dysfunction. N-Acetyl l-cysteine (NAC) and l-N(G)-Nitroarginine methyl ester (l-NAME) blocked stress-induced TJ disruption and barrier dysfunction. NAC and l-NAME also blocked stress-induced activation of c-Jun N-terminal kinase (JNK) and c-Src. ROS was colocalized with the mitochondrial marker in stressed cells. Cyclosporin A blocked osmotic stress and DSS-induced ROS production, barrier dysfunction, TJ disruption and JNK activation. Mitochondria-targeted Mito-TEMPO blocked osmotic stress and DSS-induced barrier dysfunction and TJ disruption. Chronic restraint stress in mice resulted in the elevation of intracellular Ca(2+), activation of JNK and c-Src, and disruption of TJ in the colonic epithelium. Furthermore, corticosterone administration induced JNK and c-Src activation, TJ disruption and protein thiol oxidation in colonic mucosa. The present study demonstrates that oxidative stress is a common signal in the mechanism of TJ disruption in the intestinal epithelium by different types of cellular stress in vitro and bio behavioral stress in vivo.

  5. Enteric Pathogens and Their Toxin-Induced Disruption of the Intestinal Barrier through Alteration of Tight Junctions in Chickens.

    PubMed

    Awad, Wageha A; Hess, Claudia; Hess, Michael

    2017-02-10

    utilize tight junction proteins as receptors for attachment and subsequent internalization, while others modify or destroy the tight junction proteins by different pathways and thereby provide a gateway to the underlying tissue. This review aims to deliver an overview of the tight junction structures and function, and its role in enteric bacterial pathogenesis with a special focus on chickens. A main conclusion will be that the molecular mechanisms used by enteric pathogens to disrupt epithelial barrier function in chickens needs a much better understanding, explicitly highlighted for Campylobacter jejuni, Salmonella enterica and Clostridium perfringens. This is a requirement in order to assist in discovering new strategies to avoid damages of the intestinal barrier or to minimize consequences from infections.

  6. Calcium oxalate crystals induces tight junction disruption in distal renal tubular epithelial cells by activating ROS/Akt/p38 MAPK signaling pathway.

    PubMed

    Yu, Lei; Gan, Xiuguo; Liu, Xukun; An, Ruihua

    2017-11-01

    Tight junction plays important roles in regulating paracellular transports and maintaining cell polarity. Calcium oxalate monohydrate (COM) crystals, the major crystalline composition of kidney stones, have been demonstrated to be able to cause tight junction disruption to accelerate renal cell injury. However, the cellular signaling involved in COM crystal-induced tight junction disruption remains largely to be investigated. In the present study, we proved that COM crystals induced tight junction disruption by activating ROS/Akt/p38 MAPK pathway. Treating Madin-Darby canine kidney (MDCK) cells with COM crystals induced a substantial increasing of ROS generation and activation of Akt that triggered subsequential activation of ASK1 and p38 mitogen-activated protein kinase (MAPK). Western blot revealed a significantly decreased expression of ZO-1 and occludin, two important structural proteins of tight junction. Besides, redistribution and dissociation of ZO-1 were observed by COM crystals treatment. Inhibition of ROS by N-acetyl-l-cysteine (NAC) attenuated the activation of Akt, ASK1, p38 MAPK, and down-regulation of ZO-1 and occludin. The redistribution and dissociation of ZO-1 were also alleviated by NAC treatment. These results indicated that ROS were involved in the regulation of tight junction disruption induced by COM crystals. In addition, the down-regulation of ZO-1 and occludin, the phosphorylation of ASK1 and p38 MAPK were also attenuated by MK-2206, an inhibitor of Akt kinase, implying Akt was involved in the disruption of tight junction upstream of p38 MAPK. Thus, these results suggested that ROS-Akt-p38 MAPK signaling pathway was activated in COM crystal-induced disruption of tight junction in MDCK cells.

  7. Enteric Pathogens and Their Toxin-Induced Disruption of the Intestinal Barrier through Alteration of Tight Junctions in Chickens

    PubMed Central

    Awad, Wageha A.; Hess, Claudia; Hess, Michael

    2017-01-01

    can utilize tight junction proteins as receptors for attachment and subsequent internalization, while others modify or destroy the tight junction proteins by different pathways and thereby provide a gateway to the underlying tissue. This review aims to deliver an overview of the tight junction structures and function, and its role in enteric bacterial pathogenesis with a special focus on chickens. A main conclusion will be that the molecular mechanisms used by enteric pathogens to disrupt epithelial barrier function in chickens needs a much better understanding, explicitly highlighted for Campylobacter jejuni, Salmonella enterica and Clostridium perfringens. This is a requirement in order to assist in discovering new strategies to avoid damages of the intestinal barrier or to minimize consequences from infections. PMID:28208612

  8. Tight junction disruption: Helicobacter pylori and dysregulation of the gastric mucosal barrier

    PubMed Central

    Caron, Tyler J; Scott, Kathleen E; Fox, James G; Hagen, Susan J

    2015-01-01

    Long-term chronic infection with Helicobacter pylori (H. pylori) is a risk factor for gastric cancer development. In the multi-step process that leads to gastric cancer, tight junction dysfunction is thought to occur and serve as a risk factor by permitting the permeation of luminal contents across an otherwise tight mucosa. Mechanisms that regulate tight junction function and structure in the normal stomach, or dysfunction in the infected stomach, however, are largely unknown. Although conventional tight junction components are expressed in gastric epithelial cells, claudins regulate paracellular permeability and are likely the target of inflammation or H. pylori itself. There are 27 different claudin molecules, each with unique properties that render the mucosa an intact barrier that is permselective in a way that is consistent with cell physiology. Understanding the architecture of tight junctions in the normal stomach and then changes that occur during infection is important but challenging, because most of the reports that catalog claudin expression in gastric cancer pathogenesis are contradictory. Furthermore, the role of H. pylori virulence factors, such as cytotoxin-associated gene A and vacoulating cytotoxin, in regulating tight junction dysfunction during infection is inconsistent in different gastric cell lines and in vivo, likely because non-gastric epithelial cell cultures were initially used to unravel the details of their effects on the stomach. Hampering further study, as well, is the relative lack of cultured cell models that have tight junction claudins that are consistent with native tissues. This summary will review the current state of knowledge about gastric tight junctions, normally and in H. pylori infection, and make predictions about the consequences of claudin reorganization during H. pylori infection. PMID:26523106

  9. Activation of classical estrogen receptor subtypes reduces tight junction disruption of brain endothelial cells under ischemia/reperfusion injury.

    PubMed

    Shin, Jin A; Yoon, Joo Chun; Kim, Minsuk; Park, Eun-Mi

    2016-03-01

    Ischemic stroke, which induces oxidative stress in the brain, disrupts tight junctions (TJs) between brain endothelial cells, resulting in blood-brain barrier (BBB) breakdown and brain edema. Estrogen reduces oxidative stress and protects brain endothelial cells from ischemic insult. The aim of this study was to determine the protective effects of estrogen on TJ disruption and to examine the roles of classical estrogen receptor (ER) subtypes, ERα- and ERβ, in estrogen effects in brain endothelial cells (bEnd.3) exposed to oxygen-glucose deprivation/reperfusion (OGD/R) injury. Estrogen pretreatment prevented OGD/R-induced decreases in cell viability and TJ protein levels. ERα- and ERβ-specific agonists also reduced TJ disruption. Knockdown of ERα or ERβ expression partially inhibited the effects of estrogen, but completely reversed the effects of corresponding ER subtype-specific agonists on the outcomes of OGD/R. During the early reperfusion period, activation of extracellular signal-regulated kinase1/2 and hypoxia-inducible factor 1α/vascular endothelial growth factor was associated with decreased expression of occludin and claudin-5, respectively, and these changes in TJ protein levels were differentially regulated by ER subtype-specific agonists. Our results suggest that ERα and ERβ activation reduce TJ disruption via inhibition of signaling molecules after ischemic injury and that targeting each ER subtype can be a useful strategy for protecting the BBB from ischemic stroke in postmenopausal women.

  10. Irinotecan disrupts tight junction proteins within the gut : implications for chemotherapy-induced gut toxicity.

    PubMed

    Wardill, Hannah R; Bowen, Joanne M; Al-Dasooqi, Noor; Sultani, Masooma; Bateman, Emma; Stansborough, Romany; Shirren, Joseph; Gibson, Rachel J

    2014-02-01

    Chemotherapy for cancer causes significant gut toxicity, leading to severe clinical manifestations and an increased economic burden. Despite much research, many of the underlying mechanisms remain poorly understood hindering effective treatment options. Recently there has been renewed interest in the role tight junctions play in the pathogenesis of chemotherapy-induced gut toxicity. To delineate the underlying mechanisms of chemotherapy-induced gut toxicity, this study aimed to quantify the molecular changes in key tight junction proteins, ZO-1, claudin-1, and occludin, using a well-established preclinical model of gut toxicity. Female tumor-bearing dark agouti rats received irinotecan or vehicle control and were assessed for validated parameters of gut toxicity including diarrhea and weight loss. Rats were killed at 6, 24, 48, 72, 96, and 120 h post-chemotherapy. Tight junction protein and mRNA expression in the small and large intestines were assessed using semi-quantitative immunohistochemistry and RT-PCR. Significant changes in protein expression of tight junction proteins were seen in both the jejunum and colon, correlating with key histological changes and clinical features. mRNA levels of claudin-1 were significantly decreased early after irinotecan in the small and large intestines. ZO-1 and occludin mRNA levels remained stable across the time-course of gut toxicity. Findings strongly suggest irinotecan causes tight junction defects which lead to mucosal barrier dysfunction and the development of diarrhea. Detailed research is now warranted to investigate posttranslational regulation of tight junction proteins to delineate the underlying pathophysiology of gut toxicity and identify future therapeutic targets.

  11. Apical cap

    SciTech Connect

    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.

  12. Giardia disrupts the arrangement of tight, adherens and desmosomal junction proteins of intestinal cells.

    PubMed

    Maia-Brigagão, C; Morgado-Díaz, J A; De Souza, W

    2012-06-01

    Giardia duodenalis is a parasitic protozoan that causes diarrhea and other symptoms which together constitute a disease known as giardiasis. Although the disease has been well defined, the mechanisms involving the establishment of the infection have not yet been fully elucidated. In this study, we show that after 24h of interaction between parasites and intestinal Caco-2 cells, there was an alteration of the paracellular permeability, as observed by an approximate 42% of reduction in the transepithelial electrical resistance and permeation to ruthenium red, which was concomitant with ultrastructural changes. Nevertheless, epithelium viability was not affected. We also demonstrate that there was no change in expression of junctional proteins (tight and adherens) but that the distribution of these proteins in Caco-2 cells after parasite adhesion was significantly altered, as observed via laser scanning confocal microscopy 3D reconstruction. The present work shows that adhesion of Giardia duodenalis trophozoites to intestinal cells in vitro induces disturbances of the tight, adherens and desmosomal junctions.

  13. Low-dose acetaminophen induces early disruption of cell-cell tight junctions in human hepatic cells and mouse liver.

    PubMed

    Gamal, Wesam; Treskes, Philipp; Samuel, Kay; Sullivan, Gareth J; Siller, Richard; Srsen, Vlastimil; Morgan, Katie; Bryans, Anna; Kozlowska, Ada; Koulovasilopoulos, Andreas; Underwood, Ian; Smith, Stewart; Del-Pozo, Jorge; Moss, Sharon; Thompson, Alexandra Inés; Henderson, Neil C; Hayes, Peter C; Plevris, John N; Bagnaninchi, Pierre-Olivier; Nelson, Leonard J

    2017-01-30

    Dysfunction of cell-cell tight junction (TJ) adhesions is a major feature in the pathogenesis of various diseases. Liver TJs preserve cellular polarity by delimiting functional bile-canalicular structures, forming the blood-biliary barrier. In acetaminophen-hepatotoxicity, the mechanism by which tissue cohesion and polarity are affected remains unclear. Here, we demonstrate that acetaminophen, even at low-dose, disrupts the integrity of TJ and cell-matrix adhesions, with indicators of cellular stress with liver injury in the human hepatic HepaRG cell line, and primary hepatocytes. In mouse liver, at human-equivalence (therapeutic) doses, dose-dependent loss of intercellular hepatic TJ-associated ZO-1 protein expression was evident with progressive clinical signs of liver injury. Temporal, dose-dependent and specific disruption of the TJ-associated ZO-1 and cytoskeletal-F-actin proteins, correlated with modulation of hepatic ultrastructure. Real-time impedance biosensing verified in vitro early, dose-dependent quantitative decreases in TJ and cell-substrate adhesions. Whereas treatment with NAPQI, the reactive metabolite of acetaminophen, or the PKCα-activator and TJ-disruptor phorbol-12-myristate-13-acetate, similarly reduced TJ integrity, which may implicate oxidative stress and the PKC pathway in TJ destabilization. These findings are relevant to the clinical presentation of acetaminophen-hepatotoxicity and may inform future mechanistic studies to identify specific molecular targets and pathways that may be altered in acetaminophen-induced hepatic depolarization.

  14. Low-dose acetaminophen induces early disruption of cell-cell tight junctions in human hepatic cells and mouse liver

    PubMed Central

    Gamal, Wesam; Treskes, Philipp; Samuel, Kay; Sullivan, Gareth J.; Siller, Richard; Srsen, Vlastimil; Morgan, Katie; Bryans, Anna; Kozlowska, Ada; Koulovasilopoulos, Andreas; Underwood, Ian; Smith, Stewart; del-Pozo, Jorge; Moss, Sharon; Thompson, Alexandra Inés; Henderson, Neil C.; Hayes, Peter C.; Plevris, John N.; Bagnaninchi, Pierre-Olivier; Nelson, Leonard J.

    2017-01-01

    Dysfunction of cell-cell tight junction (TJ) adhesions is a major feature in the pathogenesis of various diseases. Liver TJs preserve cellular polarity by delimiting functional bile-canalicular structures, forming the blood-biliary barrier. In acetaminophen-hepatotoxicity, the mechanism by which tissue cohesion and polarity are affected remains unclear. Here, we demonstrate that acetaminophen, even at low-dose, disrupts the integrity of TJ and cell-matrix adhesions, with indicators of cellular stress with liver injury in the human hepatic HepaRG cell line, and primary hepatocytes. In mouse liver, at human-equivalence (therapeutic) doses, dose-dependent loss of intercellular hepatic TJ-associated ZO-1 protein expression was evident with progressive clinical signs of liver injury. Temporal, dose-dependent and specific disruption of the TJ-associated ZO-1 and cytoskeletal-F-actin proteins, correlated with modulation of hepatic ultrastructure. Real-time impedance biosensing verified in vitro early, dose-dependent quantitative decreases in TJ and cell-substrate adhesions. Whereas treatment with NAPQI, the reactive metabolite of acetaminophen, or the PKCα-activator and TJ-disruptor phorbol-12-myristate-13-acetate, similarly reduced TJ integrity, which may implicate oxidative stress and the PKC pathway in TJ destabilization. These findings are relevant to the clinical presentation of acetaminophen-hepatotoxicity and may inform future mechanistic studies to identify specific molecular targets and pathways that may be altered in acetaminophen-induced hepatic depolarization. PMID:28134251

  15. Haploinsufficiency for Core Exon Junction Complex Components Disrupts Embryonic Neurogenesis and Causes p53-Mediated Microcephaly

    PubMed Central

    Wang, Zefeng; Silver, Debra L.

    2016-01-01

    The exon junction complex (EJC) is an RNA binding complex comprised of the core components Magoh, Rbm8a, and Eif4a3. Human mutations in EJC components cause neurodevelopmental pathologies. Further, mice heterozygous for either Magoh or Rbm8a exhibit aberrant neurogenesis and microcephaly. Yet despite the requirement of these genes for neurodevelopment, the pathogenic mechanisms linking EJC dysfunction to microcephaly remain poorly understood. Here we employ mouse genetics, transcriptomic and proteomic analyses to demonstrate that haploinsufficiency for each of the 3 core EJC components causes microcephaly via converging regulation of p53 signaling. Using a new conditional allele, we first show that Eif4a3 haploinsufficiency phenocopies aberrant neurogenesis and microcephaly of Magoh and Rbm8a mutant mice. Transcriptomic and proteomic analyses of embryonic brains at the onset of neurogenesis identifies common pathways altered in each of the 3 EJC mutants, including ribosome, proteasome, and p53 signaling components. We further demonstrate all 3 mutants exhibit defective splicing of RNA regulatory proteins, implying an EJC dependent RNA regulatory network that fine-tunes gene expression. Finally, we show that genetic ablation of one downstream pathway, p53, significantly rescues microcephaly of all 3 EJC mutants. This implicates p53 activation as a major node of neurodevelopmental pathogenesis following EJC impairment. Altogether our study reveals new mechanisms to help explain how EJC mutations influence neurogenesis and underlie neurodevelopmental disease. PMID:27618312

  16. Ultraviolet A radiation transiently disrupts gap junctional communication in human keratinocytes.

    PubMed

    Provost, Nicolas; Moreau, Marielle; Leturque, Armelle; Nizard, Carine

    2003-01-01

    Ultraviolet A (UVA) (320-400 nm) radiation is known to cause cutaneous aging and skin cancer. We studied the effect of UVA (365 nm) radiation on the human epidermis by focusing on keratinocyte gap junction-mediated intercellular communication (GJIC). We observed a dose-dependent 10-fold decrease in GJIC induced by UVA in normal human keratinocytes. This decrease in GJIC was associated with time-dependent internalization of connexin43 (Cx43). UVA radiation also damaged the actin cytoskeleton, as shown by microfilament disappearance. Importantly, the decrease in GJIC was transient when keratinocytes were irradiated with 10 J/cm(2) UVA, with a return to baseline values after 8 h. Concomitantly, Cx43 was relocalized and the actin cytoskeleton was restored. UVA irradiation and 12-O-tetradecanoylphorbol 13-acetate (TPA) treatment activated protein kinase C and reduced GJIC. However, Cx43 localization and phosphorylation were differently regulated by the two treatments. This suggests that at least two different pathways may mediate the observed fall in GJIC. These findings identify keratinocyte GJIC as a new UVA target that might sensitize human skin to photoaging and cancer formation.

  17. Disruption of CDH2/N-cadherin-based adherens junctions leads to apoptosis of ependymal cells and denudation of brain ventricular walls.

    PubMed

    Oliver, Cristian; González, César A; Alvial, Genaro; Flores, Carlos A; Rodríguez, Esteban M; Bátiz, Luis Federico

    2013-09-01

    Disruption/denudation of the ependymal lining has been associated with the pathogenesis of various human CNS disorders, including hydrocephalus, spina bifida aperta, and periventricular heterotopia. It has been traditionally considered that ependymal denudation is a consequence of mechanical forces such as ventricular enlargement. New evidence indicates that ependymal disruption can precede ventricular dilation, but the cellular and molecular mechanisms involved in the onset of ependymal denudation are unknown. Here, we present a novel model to study ependymal cell pathophysiology and demonstrate that selective disruption of N-cadherin-based adherens junctions is sufficient to provoke progressive ependymal denudation. Blocking N-cadherin function using specific peptides that interfere with the histidine-alanine-valine extracellular homophilic interaction domain caused early pathologic changes characterized by disruption of zonula adherens and abnormal intracellular accumulation of N-cadherin. These changes then triggered massive apoptosis of ependymal cells and denudation of brain ventricular walls. Because no typical extrinsic mechanical factors such as elevated pressure or stretching forces are involved in this model, the critical role of N-cadherin-based adherens junctions in ependymal survival/physiology is highlighted. Furthermore, the results suggest that abnormal adherens junctions between ependymal cells should be considered as key components of the pathogenesis of CNS disorders associated with ependymal denudation.

  18. Small bowel entrapment and ureteropelvic junction disruption associated with L3 Chance fracture-dislocation

    PubMed Central

    Pesenti, Sebastien; Blondel, Benjamin; Faure, Alice; Peltier, Emilie; Launay, Franck; Jouve, Jean-Luc

    2016-01-01

    Paediatric Chance fracture are rare lesions but often associated with abdominal injuries. We herein present the case of a seven years old patient who sustained an entrapment of small bowel and an ureteropelvic disruption associated with a Chance fracture and spine dislocation following a traffic accident. Initial X-rays and computed tomographic (CT) scan showed a Chance fracture with dislocation of L3 vertebra, with an incarceration of a small bowel loop in the spinal canal and a complete section of the left lumbar ureter. Paraplegia was noticed on the initial neurological examination. A posterior L2-L4 osteosynthesis was performed firstly. In a second time she underwent a sus umbilical laparotomy to release the incarcerated jejunum loop in the spinal canal. An end-to-end anastomosis was performed on a JJ probe to suture the left injured ureter. One month after the traumatism, she started to complain of severe headaches related to a leakage of cerebrospinalis fluid. Three months after the traumatism there was a clear regression of the leakage. One year after the trauma, an anterior intervertebral fusion was done. At final follow-up, no neurologic recovery was noticed. In case of Chance fracture, all physicians should think about abdominal injuries even if the patient is asymptomatic. Initial abdominal CT scan and magnetic resonance imaging provide in such case crucial info for management of the spine and the associated lesions. PMID:27672641

  19. Disruption of Tight Junctions by Cellulose Sulfate Facilitates HIV Infection: Model of Microbicide Safety

    PubMed Central

    Mesquita, Pedro M. M.; Cheshenko, Natalia; Wilson, Sarah S.; Mhatre, Mohak; Guzman, Esmeralda; Fakioglu, Esra; Keller, Marla J.; Herold, Betsy C.

    2010-01-01

    Background The lack of biomarkers that are predictive of safety is a critical gap in the development of microbicides. The present experiments were designed to evaluate the predictive value of in vitro models of microbicide safety. Methods Changes in the epithelial barrier were evaluated by measuring transepithelial electrical resistance (TER) after exposure of human epithelial cells to candidate microbicides in a dual-chamber system. The significance of observed changes was addressed by challenging cultures with human immuodeficiency virus (HIV) and measuring the ability of virus to cross the epithelium and infect target T cells cultured in the lower chamber. Results Exposure to nonoxynol-9 (N-9) or cellulose sulfate (CS), but not 9-[2-(phosphonomethoxy)propyl]adenine (also referred to as tenofovir) or PRO2000, resulted in a rapid and sustained reduction in TER and a marked increase in HIV infection of T cells cultured in the lower chamber. Moreover, CS triggered nuclear factor κB activation in peripheral blood mononuclear cells and increased HIV replication in chronically infected U1 cells. Conclusions Epithelial barrier disruption and enhanced viral replication may have contributed to the increased risk of HIV acquisition observed in phase 3 trials of N-9 and CS. Expansion of in vitro safety testing to include these models would provide a more stringent preclinical assessment of microbicide safety and may prove to be more predictive of clinical outcomes. PMID:19586414

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

    PubMed Central

    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. PMID:27454609

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

    PubMed

    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.

  2. Matrix Metalloproteinase-2 and -9 Secreted by Leukemic Cells Increase the Permeability of Blood-Brain Barrier by Disrupting Tight Junction Proteins

    PubMed Central

    Feng, Saran; Cen, Jiannong; Huang, Yihong; Shen, Hongjie; Yao, Li; Wang, Yuanyuan; Chen, Zixing

    2011-01-01

    Central nervous system (CNS) involvement remains an important cause of morbidity and mortality in acute leukemia, the mechanisms of leukemic cell infiltration into the CNS have not yet been elucidated. The blood-brain barrier (BBB) makes CNS become a refugee to leukemic cells and serves as a resource of cells that seed extraneural sites. How can the leukemic cells disrupt this barrier and invasive the CNS, even if many of the currently available chemotherapies can not cross the BBB? Tight junction in endothelial cells occupies a central role in the function of the BBB. Except the well known role of degrading extracellular matrix in metastasis of cancer cells, here we show matrix metalloproteinase (MMP)-2 and -9, secreted by leukemic cells, mediate the BBB opening by disrupting tight junction proteins in the CNS leukemia. We demonstrated that leukemic cells impaired tight junction proteins ZO-1, claudin-5 and occludin resulting in increased permeability of the BBB. However, these alterations reduced when MMP-2 and -9 activities were inhibited by RNA interference strategy or by MMP inhibitor GM6001 in an in vitro BBB model. We also found that the disruption of the BBB in company with the down-regulation of ZO-1, claudin-5 and occludin and the up-regulation of MMP-2 and -9 in mouse brain tissues with leukemic cell infiltration by confocal imaging and the assay of in situ gelatin zymography. Besides, GM6001 protected all mice against CNS leukemia. Our findings suggest that the degradation of tight junction proteins ZO-1, claudin-5 and occludin by MMP-2 and -9 secreted by leukemic cells constitutes an important mechanism in the BBB breakdown which contributes to the invasion of leukemic cells to the CNS in acute leukemia. PMID:21857898

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

    PubMed

    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.

  4. The inhibition of COPII trafficking is important for intestinal epithelial tight junction disruption during enteropathogenic Escherichia coli and Citrobacter rodentium infection.

    PubMed

    Thanabalasuriar, Ajitha; Kim, Jinoh; Gruenheid, Samantha

    2013-01-01

    Enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) are bacterial pathogens that cause severe illnesses in humans. Citrobacter rodentium is a related mouse pathogen that serves as a small animal model for EPEC and EHEC infections. EPEC, EHEC and C. rodentium translocate bacterial virulence proteins directly into host intestinal cells via a type III secretion system (T3SS). Non-LEE-encoded effector A (NleA) is a T3SS effector that is common to EPEC, EHEC and C. rodentium. NleA interacts with and inhibits the mammalian COPII complex, impairing cellular secretion; this interaction is required for bacterial virulence. Although diarrhea is a hallmark of EPEC, EHEC and C. rodentium infections, the underlying mechanisms are not well characterized. One of the essential functions of the intestine is to maintain a barrier between the lumen and submucosa. Tight junctions seal the space between adjacent epithelial cells creating this barrier. Consequently, it is thought that the disruption of intestinal epithelial tight junctions by EPEC, EHEC, and C. rodentium could result in a loss of barrier function. In this study, we demonstrate that NleA mediated COPII inhibition is required for EPEC- and C. rodentium-mediated disruption of tight junction proteins and increases in fecal water content.

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

    PubMed

    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.

  6. The Mobile bypass Signal Arrests Shoot Growth by Disrupting Shoot Apical Meristem Maintenance, Cytokinin Signaling, and WUS Transcription Factor Expression1[OPEN

    PubMed Central

    Parrott, David L.; Adhikari, Emma; Fraser, Nisa

    2016-01-01

    The bypass1 (bps1) mutant of Arabidopsis (Arabidopsis thaliana) produces a root-sourced compound (the bps signal) that moves to the shoot and is sufficient to arrest growth of a wild-type shoot; however, the mechanism of growth arrest is not understood. Here, we show that the earliest shoot defect arises during germination and is a failure of bps1 mutants to maintain their shoot apical meristem (SAM). This finding suggested that the bps signal might affect expression or function of SAM regulatory genes, and we found WUSCHEL (WUS) expression to be repressed in bps1 mutants. Repression appears to arise from the mobile bps signal, as the bps1 root was sufficient to rapidly down-regulate WUS expression in wild-type shoots. Normally, WUS is regulated by a balance between positive regulation by cytokinin (CK) and negative regulation by CLAVATA (CLV). In bps1, repression of WUS was independent of CLV, and, instead, the bps signal down-regulates CK responses. Cytokinin treatment of bps1 mutants restored both WUS expression and activity, but only in the rib meristem. How the bps signal down-regulates CK remains unknown, though the bps signal was sufficient to repress expression of one CK receptor (AHK4) and one response regulator (AHP6). Together, these data suggest that the bps signal pathway has the potential for long-distance regulation through modification of CK signaling and altering gene expression. PMID:27208247

  7. Access to Nectin Favors Herpes Simplex Virus Infection at the Apical Surface of Polarized Human Epithelial Cells▿

    PubMed Central

    Galen, Benjamin; Cheshenko, Natalia; Tuyama, Ana; Ramratnam, Bharat; Herold, Betsy C.

    2006-01-01

    Viral entry may preferentially occur at the apical or the basolateral surfaces of polarized cells, and differences may impact pathogenesis, preventative strategies, and successful implementation of viral vectors for gene therapy. The objective of these studies was to examine the polarity of herpes simplex virus (HSV) entry using several different human epithelial cell lines. Human uterine (ECC-1), colonic (CaCo-2), and retinal pigment (ARPE-19) epithelial cells were grown on collagen-coated inserts, and the polarity was monitored by measuring the transepithelial cell resistance. Controls were CaSki cells, a human cervical cell line that does not polarize in vitro. The polarized cells, but not CaSki cells, were 16- to 50-fold more susceptible to HSV infection at the apical surface than at the basolateral surface. Disruption of the tight junctions by treatment with EGTA overcame the restriction on basolateral infection but had no impact on apical infection. No differences in binding at the two surfaces were observed. Confocal microscopy demonstrated that nectin-1, the major coreceptor for HSV entry, sorted preferentially to the apical surface, overlapping with adherens and tight junction proteins. Transfection with small interfering RNA specific for nectin-1 resulted in a significant reduction in susceptibility to HSV at the apical surface but had little impact on basolateral infection. Infection from the apical but not the basolateral surface triggered focal adhesion kinase phosphorylation and led to nuclear transport of viral capsids and viral gene expression. These studies indicate that access to nectin-1 contributes to preferential apical infection of these human epithelial cells by HSV. PMID:17005657

  8. Gap junctions.

    PubMed

    Goodenough, Daniel A; Paul, David L

    2009-07-01

    Gap junctions are aggregates of intercellular channels that permit direct cell-cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hexamers of medium-sized families of integral proteins: connexins in chordates and innexins in precordates. The functions of gap junctions have been explored by studying mutations in flies, worms, and humans, and targeted gene disruption in mice. These studies have revealed a wide diversity of function in tissue and organ biology.

  9. Gap Junctions

    PubMed Central

    Goodenough, Daniel A.; Paul, David L.

    2009-01-01

    Gap junctions are aggregates of intercellular channels that permit direct cell–cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hexamers of medium-sized families of integral proteins: connexins in chordates and innexins in precordates. The functions of gap junctions have been explored by studying mutations in flies, worms, and humans, and targeted gene disruption in mice. These studies have revealed a wide diversity of function in tissue and organ biology. PMID:20066080

  10. Adenovirus fiber disrupts CAR-mediated intercellular adhesion allowing virus escape.

    PubMed

    Walters, Robert W; Freimuth, Paul; Moninger, Thomas O; Ganske, Ingrid; Zabner, Joseph; Welsh, Michael J

    2002-09-20

    Adenovirus binds its receptor (CAR), enters cells, and replicates. It must then escape to the environment to infect a new host. We found that following infection, human airway epithelia first released adenovirus to the basolateral surface. Virus then traveled between epithelial cells to emerge on the apical surface. Adenovirus fiber protein, which is produced during viral replication, facilitated apical escape. Fiber binds CAR, which sits on the basolateral membrane where it maintains tight junction integrity. When fiber bound CAR, it disrupted junctional integrity, allowing virus to filter between the cells and emerge apically. Thus, adenovirus exploits its receptor for two important but distinct steps in its life cycle: entry into host cells and escape across epithelial barriers to the environment.

  11. Uncoupling apical constriction from tissue invagination.

    PubMed

    Chung, SeYeon; Kim, Sangjoon; Andrew, Deborah J

    2017-03-06

    Apical constriction is a widely utilized cell shape change linked to folding, bending and invagination of polarized epithelia. It remains unclear how apical constriction is regulated spatiotemporally during tissue invagination and how this cellular process contributes to tube formation in different developmental contexts. Using Drosophila salivary gland (SG) invagination as a model, we show that regulation of folded gastrulation expression by the Fork head transcription factor is required for apicomedial accumulation of Rho kinase and non-muscle myosin II, which coordinate apical constriction. We demonstrate that neither loss of spatially coordinated apical constriction nor its complete blockage prevent internalization and tube formation, although such manipulations affect the geometry of invagination. When apical constriction is disrupted, compressing force generated by a tissue-level myosin cable contributes to SG invagination. We demonstrate that fully elongated polarized SGs can form outside the embryo, suggesting that tube formation and elongation are intrinsic properties of the SG.

  12. Toxicants target cell junctions in the testis: Insights from the indazole-carboxylic acid model

    PubMed Central

    Cheng, C Yan

    2014-01-01

    There are numerous types of junctions in the seminiferous epithelium which are integrated with, and critically dependent on the Sertoli cell cytoskeleton. These include the basal tight junctions between Sertoli cells that form the main component of the blood–testis barrier, the basal ectoplasmic specializations (basal ES) and basal tubulobulbar complexes (basal TBC) between Sertoli cells; as well as apical ES and apical TBC between Sertoli cells and the developing spermatids that orchestrate spermiogenesis and spermiation. These junctions, namely TJ, ES, and TBC interact with actin microfilament-based cytoskeleton, which together with the desmosomal junctions that interact with the intermediate filament-based cytoskeleton plus the highly polarized microtubule-based cytoskeleton are working in concert to move spermatocytes and spermatids between the basal and luminal aspect of the seminiferous epithelium. In short, these various junctions are structurally complexed with the actin- and microtubule-based cytoskeleton or intermediate filaments of the Sertoli cell. Studies have shown toxicants (e.g., cadmium, bisphenol A (BPA), perfluorooctanesulfonate (PFOS), phthalates, and glycerol), and some male contraceptives under development (e.g., adjudin, gamendazole), exert their effects, at least in part, by targeting cell junctions in the testis. The disruption of Sertoli–Sertoli cell and Sertoli–germ cell junctions, results in the loss of germ cells from the seminiferous epithelium. Adjudin, a potential male contraceptive under investigation in our laboratory, produces loss of spermatids from the seminiferous tubules through disruption of the Sertoli cell spermatid junctions and disruption of the Sertoli cell cytoskeleton. The molecular and structural changes associated with adjudin administration are described, to provide an example of the profile of changes caused by disturbance of Sertoli-germ cell and also Sertoli cell-cell junctions. PMID:26413399

  13. Knockdown of col22a1 gene in zebrafish induces a muscular dystrophy by disruption of the myotendinous junction.

    PubMed

    Charvet, Benjamin; Guiraud, Alexandre; Malbouyres, Marilyne; Zwolanek, Daniela; Guillon, Emilie; Bretaud, Sandrine; Monnot, Catherine; Schulze, Jörg; Bader, Hannah L; Allard, Bruno; Koch, Manuel; Ruggiero, Florence

    2013-11-01

    The myotendinous junction (MTJ) is the major site of force transfer in skeletal muscle, and defects in its structure correlate with a subset of muscular dystrophies. Col22a1 encodes the MTJ component collagen XXII, the function of which remains unknown. Here, we have cloned and characterized the zebrafish col22a1 gene and conducted morpholino-based loss-of-function studies in developing embryos. We showed that col22a1 transcripts localize at muscle ends when the MTJ forms and that COLXXII protein integrates the junctional extracellular matrix. Knockdown of COLXXII expression resulted in muscular dystrophy-like phenotype, including swimming impairment, curvature of embryo trunk/tail, strong reduction of twitch-contraction amplitude and contraction-induced muscle fiber detachment, and provoked significant activation of the survival factor Akt. Electron microscopy and immunofluorescence studies revealed that absence of COLXXII caused a strong reduction of MTJ folds and defects in myoseptal structure. These defects resulted in reduced contractile force and susceptibility of junctional extracellular matrix to rupture when subjected to repeated mechanical stress. Co-injection of sub-phenotypic doses of morpholinos against col22a1 and genes of the major muscle linkage systems showed a synergistic gene interaction between col22a1 and itga7 (α7β1 integrin) that was not observed with dag1 (dystroglycan). Finally, pertinent to a conserved role in humans, the dystrophic phenotype was rescued by microinjection of recombinant human COLXXII. Our findings indicate that COLXXII contributes to the stabilization of myotendinous junctions and strengthens skeletal muscle attachments during contractile activity.

  14. Genomic and Proteomic Profiling Reveals Reduced Mitochondrial Function and Disruption of the Neuromuscular Junction Driving Rat Sarcopenia

    PubMed Central

    Ibebunjo, Chikwendu; Chick, Joel M.; Kendall, Tracee; Eash, John K.; Li, Christine; Zhang, Yunyu; Vickers, Chad; Wu, Zhidan; Clarke, Brian A.; Shi, Jun; Cruz, Joseph; Fournier, Brigitte; Brachat, Sophie; Gutzwiller, Sabine; Ma, QiCheng; Markovits, Judit; Broome, Michelle; Steinkrauss, Michelle; Skuba, Elizabeth; Galarneau, Jean-Rene; Gygi, Steven P.

    2013-01-01

    Molecular mechanisms underlying sarcopenia, the age-related loss of skeletal muscle mass and function, remain unclear. To identify molecular changes that correlated best with sarcopenia and might contribute to its pathogenesis, we determined global gene expression profiles in muscles of rats aged 6, 12, 18, 21, 24, and 27 months. These rats exhibit sarcopenia beginning at 21 months. Correlation of the gene expression versus muscle mass or age changes, and functional annotation analysis identified gene signatures of sarcopenia distinct from gene signatures of aging. Specifically, mitochondrial energy metabolism (e.g., tricarboxylic acid cycle and oxidative phosphorylation) pathway genes were the most downregulated and most significantly correlated with sarcopenia. Also, perturbed were genes/pathways associated with neuromuscular junction patency (providing molecular evidence of sarcopenia-related functional denervation and neuromuscular junction remodeling), protein degradation, and inflammation. Proteomic analysis of samples at 6, 18, and 27 months confirmed the depletion of mitochondrial energy metabolism proteins and neuromuscular junction proteins. Together, these findings suggest that therapeutic approaches that simultaneously stimulate mitochondrogenesis and reduce muscle proteolysis and inflammation have potential for treating sarcopenia. PMID:23109432

  15. Quantitative apical membrane proteomics reveals vasopressin-induced actin dynamics in collecting duct cells

    PubMed Central

    Loo, Chin-San; Chen, Cheng-Wei; Wang, Po-Jen; Chen, Pei-Yu; Lin, Shu-Yu; Khoo, Kay-Hooi; Fenton, Robert A.; Knepper, Mark A.; Yu, Ming-Jiun

    2013-01-01

    In kidney collecting duct cells, filamentous actin (F-actin) depolymerization is a critical step in vasopressin-induced trafficking of aquaporin-2 to the apical plasma membrane. However, the molecular components of this response are largely unknown. Using stable isotope-based quantitative protein mass spectrometry and surface biotinylation, we identified 100 proteins that showed significant abundance changes in the apical plasma membrane of mouse cortical collecting duct cells in response to vasopressin. Fourteen of these proteins are involved in actin cytoskeleton regulation, including actin itself, 10 actin-associated proteins, and 3 regulatory proteins. Identified were two integral membrane proteins (Clmn, Nckap1) and one actin-binding protein (Mpp5) that link F-actin to the plasma membrane, five F-actin end-binding proteins (Arpc2, Arpc4, Gsn, Scin, and Capzb) involved in F-actin reorganization, and two actin adaptor proteins (Dbn1, Lasp1) that regulate actin cytoskeleton organization. There were also protease (Capn1), protein kinase (Cdc42bpb), and Rho guanine nucleotide exchange factor 2 (Arhgef2) that mediate signal-induced F-actin changes. Based on these findings, we devised a live-cell imaging method to observe vasopressin-induced F-actin dynamics in polarized mouse cortical collecting duct cells. In response to vasopressin, F-actin gradually disappeared near the center of the apical plasma membrane while consolidating laterally near the tight junction. This F-actin peripheralization was blocked by calcium ion chelation. Vasopressin-induced apical aquaporin-2 trafficking and forskolin-induced water permeability increase were blocked by F-actin disruption. In conclusion, we identified a vasopressin-regulated actin network potentially responsible for vasopressin-induced apical F-actin dynamics that could explain regulation of apical aquaporin-2 trafficking and water permeability increase. PMID:24085853

  16. Lipopolysaccharide-Induced Middle Ear Inflammation Disrupts the cochlear Intra-Strial Fluid–Blood Barrier through Down-Regulation of Tight Junction Proteins

    PubMed Central

    Zhang, Jinhui; Chen, Songlin; Hou, Zhiqiang; Cai, Jing; Dong, Mingmin; Shi, Xiaorui

    2015-01-01

    Middle ear infection (or inflammation) is the most common pathological condition that causes fluid to accumulate in the middle ear, disrupting cochlear homeostasis. Lipopolysaccharide, a product of bacteriolysis, activates macrophages and causes release of inflammatory cytokines. Many studies have shown that lipopolysaccharides cause functional and structural changes in the inner ear similar to that of inflammation. However, it is specifically not known how lipopolysaccharides affect the blood-labyrinth barrier in the stria vascularis (intra-strial fluid–blood barrier), nor what the underlying mechanisms are. In this study, we used a cell culture-based in vitro model and animal-based in vivo model, combined with immunohistochemistry and a vascular leakage assay, to investigate lipopolysaccharide effects on the integrity of the mouse intra-strial fluid–blood barrier. Our results show lipopolysaccharide-induced local infection significantly affects intra-strial fluid–blood barrier component cells. Pericytes and perivascular-resident macrophage-like melanocytes are particularly affected, and the morphological and functional changes in these cells are accompanied by substantial changes in barrier integrity. Significant vascular leakage is found in the lipopolysaccharide treated-animals. Consistent with the findings from the in vivo animal model, the permeability of the endothelial cell monolayer to FITC-albumin was significantly higher in the lipopolysaccharide-treated monolayer than in an untreated endothelial cell monolayer. Further study has shown the lipopolysaccharide-induced inflammation to have a major effect on the expression of tight junctions in the blood barrier. Lipopolysaccharide was also shown to cause high frequency hearing loss, corroborated by previous reports from other laboratories. Our findings show lipopolysaccharide-evoked middle ear infection disrupts inner ear fluid balance, and its particular effects on the intra-strial fluid

  17. Lipopolysaccharide-induced middle ear inflammation disrupts the cochlear intra-strial fluid-blood barrier through down-regulation of tight junction proteins.

    PubMed

    Zhang, Jinhui; Chen, Songlin; Hou, Zhiqiang; Cai, Jing; Dong, Mingmin; Shi, Xiaorui

    2015-01-01

    Middle ear infection (or inflammation) is the most common pathological condition that causes fluid to accumulate in the middle ear, disrupting cochlear homeostasis. Lipopolysaccharide, a product of bacteriolysis, activates macrophages and causes release of inflammatory cytokines. Many studies have shown that lipopolysaccharides cause functional and structural changes in the inner ear similar to that of inflammation. However, it is specifically not known how lipopolysaccharides affect the blood-labyrinth barrier in the stria vascularis (intra-strial fluid-blood barrier), nor what the underlying mechanisms are. In this study, we used a cell culture-based in vitro model and animal-based in vivo model, combined with immunohistochemistry and a vascular leakage assay, to investigate lipopolysaccharide effects on the integrity of the mouse intra-strial fluid-blood barrier. Our results show lipopolysaccharide-induced local infection significantly affects intra-strial fluid-blood barrier component cells. Pericytes and perivascular-resident macrophage-like melanocytes are particularly affected, and the morphological and functional changes in these cells are accompanied by substantial changes in barrier integrity. Significant vascular leakage is found in the lipopolysaccharide treated-animals. Consistent with the findings from the in vivo animal model, the permeability of the endothelial cell monolayer to FITC-albumin was significantly higher in the lipopolysaccharide-treated monolayer than in an untreated endothelial cell monolayer. Further study has shown the lipopolysaccharide-induced inflammation to have a major effect on the expression of tight junctions in the blood barrier. Lipopolysaccharide was also shown to cause high frequency hearing loss, corroborated by previous reports from other laboratories. Our findings show lipopolysaccharide-evoked middle ear infection disrupts inner ear fluid balance, and its particular effects on the intra-strial fluid-blood barrier

  18. Direct Exposure to Ethanol Disrupts Junctional Cell-Cell Contact and Hippo-YAP Signaling in HL-1 Murine Atrial Cardiomyocytes

    PubMed Central

    Noritake, Kanako; Aki, Toshihiko; Funakoshi, Takeshi; Unuma, Kana; Uemura, Koichi

    2015-01-01

    Direct exposure of cardiomyocytes to ethanol causes cardiac damage such as cardiac arrythmias and apoptotic cell death. Cardiomyocytes are connected to each other through intercalated disks (ID), which are composed of a gap junction (GJ), adherens junction, and desmosome. Changes in the content as well as the subcellular localization of connexin43 (Cx43), the main component of the cardiac GJ, are reportedly involved in cardiac arrythmias and subsequent damage. Recently, the hippo-YAP signaling pathway, which links cellular physical status to cell proliferation, differentiation, and apoptosis, has been implicated in cardiac homeostasis under physiological as well as pathological conditions. This study was conducted to explore the possible involvement of junctional intercellular communication, mechanotransduction through cytoskeletal organization, and the hippo-YAP pathway in cardiac damage caused by direct exposure to ethanol. HL-1 murine atrial cardiac cells were used since these cells retain cardiac phenotypes through ID formation and subsequent synchronous contraction. Cells were exposed to 0.5–2% ethanol; significant apoptotic cell death was observed after exposure to 2% ethanol for 48 hours. A decrease in Cx43 levels was already observed after 3 hours exposure to 2% ethanol, suggesting a rapid degradation of this protein. Upon exposure to ethanol, Cx43 translocated into lysosomes. Cellular cytoskeletal organization was also dysregulated by ethanol, as demonstrated by the disruption of myofibrils and intermediate filaments. Coinciding with the loss of cell-cell adherence, decreased phosphorylation of YAP, a hippo pathway effector, was also observed in ethanol-treated cells. Taken together, the results provide evidence that cells exposed directly to ethanol show 1) impaired cell-cell adherence/communication, 2) decreased cellular mechanotransduction by the cytoskeleton, and 3) a suppressed hippo-YAP pathway. Suppression of hippo-YAP pathway signaling should be

  19. Reversal of West Nile virus-induced blood-brain barrier disruption and tight junction proteins degradation by matrix metalloproteinases inhibitor

    PubMed Central

    Verma, Saguna; Kumar, Mukesh; Gurjav, Ulziijargal; Lum, Stephanie; Nerurkar, Vivek R.

    2011-01-01

    Though compromised blood-brain barrier (BBB) is a pathological hallmark of WNV- associated neurological sequelae, underlying mechanisms are unclear. We characterized the expression of matrix metalloproteinases (MMP) in WNV-infected human brain-microvascular endothelial cells (HBMVE) and -cortical astrocytes (HBCA), components of BBB and their role in BBB disruption. Expression of multiple MMPs was significantly induced in WNV-infected HBCA cells. Naïve HBMVE cells incubated with the supernatant from WNV-infected HBCA cells demonstrated loss of tight junction proteins, which was rescued in the presence of MMP inhibitor, GM6001. Further, supernatant from WNV-infected HBCA cells compromised the in-vitro BBB models integrity. Our data suggests astrocytes as one of the sources of MMP in the brain, which mediates BBB disruption allowing unrestricted entry of immune cells into the brain, thereby contributing to WNV-neuropathogenesis. Because of the unavailability of WNV antivirals and vaccines, use of MMP inhibitors as an adjunct therapy to ameliorate WNV disease progression is warranted. PMID:19922973

  20. Necrotizing Enterocolitis in a mouse model leads to widespread renal inflammation, acute kidney injury and disruption of renal tight junction proteins

    PubMed Central

    Garg, Parvesh M; Tatum, Rodney; Ravisankar, Srikanth; Shekhawat, Prem S; Chen, Yan-Hua

    2015-01-01

    BACKGROUND Necrotizing enterocolitis (NEC) is a devastating condition affecting premature infants and leads to high mortality and chronic morbidity. Severe form of NEC is associated with acute renal failure, fluid imbalance, hyponatremia and acidosis. We investigated the effect of NEC on tight junction (TJ) proteins in kidneys using a NEC mouse model to investigate the basis for the observed renal dysfunction. METHODS NEC was induced in C57BL/6 mice by formula feeding and subjecting them to periods of hypoxia and cold stress. NEC was confirmed by gross and histological examination. We studied various markers of inflammation in kidneys and investigated changes in expression of several TJ proteins and AQP2 using immunofluorecent staining and Western blotting. RESULTS We found markedly increased expression of NFκB, TGFβ and ERK1/2 along with claudin-1, -2, -3, -4, -8 and AQP-2 in NEC kidneys. The membrane localization of claudin-2 was altered in the NEC kidneys and its immunostaining signal at TJ was disrupted. CONCLUSION NEC led to a severe inflammatory response not only in the gut but also the kidneys. NEC increased expression of several TJ proteins and caused disruption of claudin-2 in renal tubules. These observed changes can help explain some of the clinical findings observed in NEC. PMID:26270572

  1. ATP Induces Disruption of Tight Junction Proteins via IL-1 Beta-Dependent MMP-9 Activation of Human Blood-Brain Barrier In Vitro.

    PubMed

    Yang, Fuxing; Zhao, Kai; Zhang, Xiufeng; Zhang, Jun; Xu, Bainan

    2016-01-01

    Disruption of blood-brain barrier (BBB) follows brain trauma or central nervous system (CNS) stress. However, the mechanisms leading to this process or the underlying neural plasticity are not clearly known. We hypothesized that ATP/P2X7R signaling regulates the integrity of BBB. Activation of P2X7 receptor (P2X7R) by ATP induces the release of interleukin-1β (IL-1β), which in turn enhances the activity of matrix metalloproteinase-9 (MMP-9). Degradation of tight junction proteins (TJPs) such as ZO-1 and occludin occurs, which finally contributes to disruption of BBB. A contact coculture system using human astrocytes and hCMEC/D3, an immortalized human brain endothelial cell line, was used to mimic BBB in vitro. Permeability was used to evaluate changes in the integrity of TJPs. ELISA, Western blot, and immunofluorescent staining procedures were used. Our data demonstrated that exposure to the photoreactive ATP analog, 3'-O-(4-benzoyl)benzoyl adenosine 5'-triphosphate (BzATP), induced a significant decrease in ZO-1 and occludin expression. Meanwhile, the decrease of ZO-1 and occludin was significantly attenuated by P2X7R inhibitors, as well as IL-1R and MMP antagonists. Further, the induction of IL-1β and MMP-9 was closely linked to ATP/P2X7R-associated BBB leakage. In conclusion, our study explored the mechanism of ATP/P2X7R signaling in the disruption of BBB following brain trauma/stress injury, especially focusing on the relationship with IL-1β and MMP-9.

  2. ATP Induces Disruption of Tight Junction Proteins via IL-1 Beta-Dependent MMP-9 Activation of Human Blood-Brain Barrier In Vitro

    PubMed Central

    Zhao, Kai

    2016-01-01

    Disruption of blood-brain barrier (BBB) follows brain trauma or central nervous system (CNS) stress. However, the mechanisms leading to this process or the underlying neural plasticity are not clearly known. We hypothesized that ATP/P2X7R signaling regulates the integrity of BBB. Activation of P2X7 receptor (P2X7R) by ATP induces the release of interleukin-1β (IL-1β), which in turn enhances the activity of matrix metalloproteinase-9 (MMP-9). Degradation of tight junction proteins (TJPs) such as ZO-1 and occludin occurs, which finally contributes to disruption of BBB. A contact coculture system using human astrocytes and hCMEC/D3, an immortalized human brain endothelial cell line, was used to mimic BBB in vitro. Permeability was used to evaluate changes in the integrity of TJPs. ELISA, Western blot, and immunofluorescent staining procedures were used. Our data demonstrated that exposure to the photoreactive ATP analog, 3′-O-(4-benzoyl)benzoyl adenosine 5′-triphosphate (BzATP), induced a significant decrease in ZO-1 and occludin expression. Meanwhile, the decrease of ZO-1 and occludin was significantly attenuated by P2X7R inhibitors, as well as IL-1R and MMP antagonists. Further, the induction of IL-1β and MMP-9 was closely linked to ATP/P2X7R-associated BBB leakage. In conclusion, our study explored the mechanism of ATP/P2X7R signaling in the disruption of BBB following brain trauma/stress injury, especially focusing on the relationship with IL-1β and MMP-9. PMID:27795859

  3. Lecithin-Bound Iodine Prevents Disruption of Tight Junctions of Retinal Pigment Epithelial Cells under Hypoxic Stress

    PubMed Central

    Sugimoto, Masahiko; Kondo, Mineo

    2016-01-01

    Aim. We investigated whether lecithin-bound iodine (LBI) can protect the integrity of tight junctions of retinal pigment epithelial cells from hypoxia. Method. Cultured human retinal pigment epithelial (ARPE-19) cells were pretreated with LBI. To mimic hypoxic conditions, cells were incubated with CoCl2. We compared the integrity of the tight junctions (TJs) of control to cells with either LBI alone, CoCl2 alone, or LBI + CoCl2. The levels of cytokines in the conditioned media were also determined. Results. Significant decrease in the zonula occludens-1 (ZO-1) intensity in the CoCl2 group compared to the control (5787.7 ± 4126.4 in CoCl2 group versus 29244.6 ± 2981.2 in control; average ± standard deviation). But the decrease was not significant in the LBI + CoCl2 (27189.0 ± 11231.1). The levels of monocyte chemoattractant protein-1 (MCP-1) and Chemokine (C-C Motif) Ligand 11 (CCL-11) were significantly higher in the CoCl2 than in the control (340.8 ± 43.3 versus 279.7 ± 68.3 pg/mL for MCP-1, and 15.2 ± 12.9 versus 12.5 ± 6.1 pg/mL for CCL-11. With LBI pretreatment, the levels of both cytokines were decreased to 182.6 ± 23.8 (MCP-1) and 5.46 ± 1.9 pg/mL for CCL-11). Blockade of MCP-1 or CCL-11 also shows similar result representing TJ protection from hypoxic stress. Conclusions. LBI results in a protective action from hypoxia. PMID:27340563

  4. Negatively Charged Silver Nanoparticles Cause Retinal Vascular Permeability by Activating Plasma Contact System and Disrupting Adherens Junction

    PubMed Central

    Long, Yan-Min; Zhao, Xing-Chen; Clermont, Allen C.; Zhou, Qun-Fang; Liu, Qian; Feener, Edward P.; Yan, Bing; Jiang, Gui-Bin

    2016-01-01

    Silver nanoparticles (AgNPs) have been extensively used as antibacterial component in numerous healthcare, biomedical, and consumer products. Therefore, their adverse effects to biological systems have become a major concern. AgNPs have been shown to be absorbed into circulation and redistributed into various organs. It is thus of great importance to understand how these nanoparticles affect vascular permeability and uncover the underlying molecular mechanisms. A negatively charged mecaptoundeonic acid capped silver nanoparticle (MUA@AgNP) was investigated in this work. Ex-vivo experiments in mouse plasma revealed that MUA@AgNPs caused plasma prekallikrein cleavage, while positively charged or neutral AgNPs, as well as Ag ions had no effect. In-vitro tests revealed that MUA@AgNPs activated the plasma kallikrein-kinin system (KKS) by triggering Hageman factor autoactivation. By using specific inhibitors aprotinin and HOE 140, we demonstrated that KKS activation caused the release of bradykinin, which activated B2 receptors and induced the shedding of adherens junction protein, VE-cadherin. These biological perturbations eventually resulted in endothelial paracellular permeability in mouse retina after intravitreal injection of MUA@AgNPs. The findings from this work provided key insights for toxicity modulation and biomedical applications of AgNPs. PMID:26399585

  5. Negatively charged silver nanoparticles cause retinal vascular permeability by activating plasma contact system and disrupting adherens junction.

    PubMed

    Long, Yan-Min; Zhao, Xing-Chen; Clermont, Allen C; Zhou, Qun-Fang; Liu, Qian; Feener, Edward P; Yan, Bing; Jiang, Gui-Bin

    2016-01-01

    Silver nanoparticles (AgNPs) have been extensively used as antibacterial component in numerous healthcare, biomedical and consumer products. Therefore, their adverse effects to biological systems have become a major concern. AgNPs have been shown to be absorbed into circulation and redistributed into various organs. It is thus of great importance to understand how these nanoparticles affect vascular permeability and uncover the underlying molecular mechanisms. A negatively charged mecaptoundeonic acid-capped silver nanoparticle (MUA@AgNP) was investigated in this work. Ex vivo experiments in mouse plasma revealed that MUA@AgNPs caused plasma prekallikrein cleavage, while positively charged or neutral AgNPs, as well as Ag ions had no effect. In vitro tests revealed that MUA@AgNPs activated the plasma kallikrein-kinin system (KKS) by triggering Hageman factor autoactivation. By using specific inhibitors aprotinin and HOE 140, we demonstrated that KKS activation caused the release of bradykinin, which activated B2 receptors and induced the shedding of adherens junction protein, VE-cadherin. These biological perturbations eventually resulted in endothelial paracellular permeability in mouse retina after intravitreal injection of MUA@AgNPs. The findings from this work provided key insights for toxicity modulation and biomedical applications of AgNPs.

  6. miR-200b inhibits TNF-α-induced IL-8 secretion and tight junction disruption of intestinal epithelial cells in vitro.

    PubMed

    Shen, Yujie; Zhou, Min; Yan, Junkai; Gong, Zizhen; Xiao, Yongtao; Zhang, Cong; Du, Peng; Chen, Yingwei

    2017-02-01

    Inflammatory bowel diseases (IBDs) are chronic, inflammatory disorders of the gastrointestinal tract with unclear etiologies. Intestinal epithelial cells (IECs), containing crypt and villus enterocytes, occupy a critical position in the pathogenesis of IBDs and are a major producer of immunoregulatory cytokines and a key component of the intact epithelial barrier. Previously, we have reported that miR-200b is involved in the progression of IBDs and might maintain the integrity of the intestinal epithelial barrier via reducing the loss of enterocytes. In this study, we further investigated the impact of miR-200b on intestinal epithelial inflammation and tight junctions in two distinct differentiated states of Caco-2 cells after TNF-α treatment. We demonstrated that TNF-α-enhanced IL-8 expression was decreased by microRNA (miR)-200b in undifferentiated IECs. Simultaneously, miR-200b could alleviate TNF-α-induced tight junction (TJ) disruption in well-differentiated IECs by reducing the reduction in the transepithelial electrical resistance (TEER), inhibiting the increase in paracellular permeability, and preventing the morphological redistribution of the TJ proteins claudin 1 and ZO-1. The expression levels of the JNK/c-Jun/AP-1 and myosin light chain kinase (MLCK)/phosphorylated myosin light chain (p-MLC) pathways were attenuated in undifferentiated and differentiated enterocytes, respectively. Furthermore, a dual-luciferase reporter gene detection system provided direct evidence that c-Jun and MLCK were the specific targets of miR-200b. Collectively, our results highlighted that miR-200b played a positive role in IECs via suppressing intestinal epithelial IL-8 secretion and attenuating TJ damage in vitro, which suggested that miR-200b might be a promising strategy for IBD therapy.

  7. The vascular endothelial growth factor-induced disruption of gap junctions is relayed by an autocrine communication via ATP release in coronary capillary endothelium.

    PubMed

    Thuringer, Dominique

    2004-12-01

    Little is known concerning how the coordination of Ca(2+) signaling aids in capillary endothelial cell (CEC) functions, such as microvascular permeability and angiogenesis. Previous reports support the major involvement of gap junction (GJ) channels. However, the cell-to-cell communication may not be straightforward, especially if we consider the participation of active molecules released by CEC. In this study, short-term effects of vascular endothelial growth factor (VEGF-165) were compared with those of bradykinin (BK) on gap junction coupling (GJC) and remodeling of connexin-43 (Cx43) and then analyzed for intercellular Ca(2+) signal in primary cultures of coronary CEC. Dye-coupling experiments revealed that BK or VEGF completely blocked GJC. These effects correlated with the rapid internalization of Cx43 and its tyrosine phosphorylation in part via the phosphatidylinositol 3-kinase/Akt pathway. GJC slowly recovered with BK but not with VEGF in the following hour. In control conditions, mechanical stimulation of a single cell within a confluent monolayer triggered an intercellular Ca(2+) wave that was partially inhibited by GJC blockers or purinergic inhibitors. No wave propagation was observed after blockage of both GJC and purinergic receptors. Cell treatment with VEGF also reduced propagation of the Ca(2+) wave, which was totally prevented by applying a purinergic receptor antagonist but not with a GJC blocker. That excludes purine efflux through Cx hemichannels. We conclude that VEGF-induced disruption of GJC via Cx43 remodeling is relayed by an autocrine communication via secretion of ATP to preserve intercellular Ca(2+) signaling in capillary endothelium.

  8. Matrix metalloproteinase-mediated disruption of tight junction proteins in cerebral vessels is reversed by synthetic matrix metalloproteinase inhibitor in focal ischemia in rat.

    PubMed

    Yang, Yi; Estrada, Eduardo Y; Thompson, Jeffrey F; Liu, Wenlan; Rosenberg, Gary A

    2007-04-01

    Matrix metalloproteinases (MMPs) disrupt the blood-brain barrier (BBB) during reperfusion. Occludin and claudins are recently described tight junction proteins (TJPs) that form the BBB. We hypothesized that the opening of the BBB was because of the degradation of TJPs by the MMPs. Spontaneously hypertensive rats had a 90 mins middle cerebral artery occlusion with reperfusion for 2, 3, or 24 h. Matrix metalloproteinases were measured by immunohistochemistry and in situ and gel zymography. Real-time polymerase chain reaction (PCR) measured mRNAs of MMP-2 and -9, furin, membrane-type MMP (MT1-MMP), occludin, and claudin-5. There was opening of the BBB in the piriform cortex after 3 h of reperfusion, and an MMP inhibitor, BB-1101 (30 mg/kg), prevented the opening. At 3 h, in situ zymograms showed gelatinase activity. Zymography and PCR showed greater increases in MMP-2 than in MMP-9. There were increased mRNA and immunohistochemistry for MT1-MMP and furin, which activate MMP-2. Claudin-5 and occludin mRNA expression decreased at 2 h in both hemispheres with fragments of both proteins seen on Western blot by 3 h on the ischemic side; treatment with BB-1101 reversed the degradation of the TJPs. Immunohistochemistry at 3 h showed fragmented TJPs within the endothelial cell clefts. By 24 h, in situ zymography showed gelatinase activity and gel zymography showed elevated levels of MMP-9. Disrupted TJPs previously seen in endothelial cells appeared in the surrounding astrocytes. Our results provide direct evidence that MMPs open the BBB by degrading TJPs and that an MMP inhibitor prevents degradation of the TJPs by MMPs.

  9. Uncoupling apical constriction from tissue invagination

    PubMed Central

    Chung, SeYeon; Kim, Sangjoon; Andrew, Deborah J

    2017-01-01

    Apical constriction is a widely utilized cell shape change linked to folding, bending and invagination of polarized epithelia. It remains unclear how apical constriction is regulated spatiotemporally during tissue invagination and how this cellular process contributes to tube formation in different developmental contexts. Using Drosophila salivary gland (SG) invagination as a model, we show that regulation of folded gastrulation expression by the Fork head transcription factor is required for apicomedial accumulation of Rho kinase and non-muscle myosin II, which coordinate apical constriction. We demonstrate that neither loss of spatially coordinated apical constriction nor its complete blockage prevent internalization and tube formation, although such manipulations affect the geometry of invagination. When apical constriction is disrupted, compressing force generated by a tissue-level myosin cable contributes to SG invagination. We demonstrate that fully elongated polarized SGs can form outside the embryo, suggesting that tube formation and elongation are intrinsic properties of the SG. DOI: http://dx.doi.org/10.7554/eLife.22235.001 PMID:28263180

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

    PubMed Central

    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

  11. HIV-1 gp120 Glycoprotein Interacting with Dendritic Cell-specific Intercellular Adhesion Molecule 3-grabbing Non-integrin (DC-SIGN) Down-Regulates Tight Junction Proteins to Disrupt the Blood Retinal Barrier and Increase Its Permeability.

    PubMed

    Qian, Yi-Wen; Li, Chuan; Jiang, Ai-Ping; Ge, Shengfang; Gu, Ping; Fan, Xianqun; Li, Tai-Sheng; Jin, Xia; Wang, Jian-Hua; Wang, Zhi-Liang

    2016-10-28

    Approximately 70% of HIV-1 infected patients acquire ocular opportunistic infections and manifest eye disorders during the course of their illness. The mechanisms by which pathogens invade the ocular site, however, are unclear. Under normal circumstances, vascular endothelium and retinal pigment epithelium (RPE), which possess a well developed tight junction complex, form the blood-retinal barrier (BRB) to prevent pathogen invasion. We hypothesize that disruption of the BRB allows pathogen entry into ocular sites. The hypothesis was tested using in vitro models. We discovered that human RPE cells could bind to either HIV-1 gp120 glycoproteins or HIV-1 viral particles. Furthermore, the binding was mediated by dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) expressed on RPE cells. Upon gp120 binding to DC-SIGN, cellular NF-κB signaling was triggered, leading to the induction of matrix metalloproteinases, which subsequently degraded tight junction proteins and disrupted the BRB integrity. DC-SIGN knockdown or prior blocking with a specific antibody abolished gp120-induced matrix metalloproteinase expression and reduced the degradation of tight junction proteins. This study elucidates a novel mechanism by which HIV, type 1 invades ocular tissues and provides additional insights into the translocation or invasion process of ocular complication-associated pathogens.

  12. Left ventricular apical diseases.

    PubMed

    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.

  13. Tight junction proteins: from barrier to tumorigenesis.

    PubMed

    Runkle, E Aaron; Mu, David

    2013-08-28

    The tight junction is a multi-protein complex and is the apical most junctional complex in certain epithelial and endothelial cells. A great deal of attention has been devoted to the understanding of these proteins in contributing to the barrier function - that is, regulating the paracellular flux or permeability between adjacent cells. However, tight junction proteins are now recognized as having functions beyond the barrier. The focus of this review is to discuss the barrier function of the tight junction and to summarize the literature with a focus on the role of tight junction proteins in proliferation, transformation, and metastasis.

  14. Tight Junction Proteins: From Barrier to Tumorigenesis

    PubMed Central

    Runkle, E. Aaron; Mu, David

    2013-01-01

    The tight junction is a multi-protein complex and is the apical most junctional complex in certain epithelial and endothelial cells. A great deal of attention has been devoted to the understanding of these proteins in contributing to the barrier function - that is, regulating the paracellular flux or permeability between adjacent cells. However, tight junction proteins are now recognized as having functions beyond the barrier. The focus of this review is to discuss the barrier function of the tight junction and to summarize the literature with a focus on the role of tight junction proteins in proliferation, transformation, and metastasis. PMID:23743355

  15. Two Cases of Apical Ballooning Syndrome Masking Apical Hypertrophic Cardiomyopathy

    PubMed Central

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

    2014-01-01

    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. PMID:24808780

  16. The serine protease-mediated increase in intestinal epithelial barrier function is dependent on occludin and requires an intact tight junction.

    PubMed

    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.

  17. Increased intestinal permeability and tight junction disruption by altered expression and localization of occludin in a murine graft versus host disease model

    PubMed Central

    2011-01-01

    Background Hematopoietic stem cell transplantation is increasingly performed for hematologic diseases. As a major side effect, acute graft versus host disease (GvHD) with serious gastrointestinal symptoms including diarrhea, gastrointestinal bleeding and high mortality can be observed. Because surveillance and biopsies of human gastrointestinal GvHD are difficult to perform, rare information of the alterations of the gastrointestinal barrier exists resulting in a need for systematic animal models. Methods To investigate the effects of GvHD on the intestinal barrier of the small intestine we utilized an established acute semi allogenic GvHD in C57BL/6 and B6D2F1 mice. Results By assessing the differential uptake of lactulose and mannitol in the jejunum, we observed an increased paracellular permeability as a likely mechanism for disturbed intestinal barrier function. Electron microscopy, immunohistochemistry and PCR analysis indicated profound changes of the tight-junction complex, characterized by downregulation of the tight junction protein occludin without any changes in ZO-1. Furthermore TNF-α expression was significantly upregulated. Conclusions This analysis in a murine model of GvHD of the small intestine demonstrates serious impairment of intestinal barrier function in the jejunum, with an increased permeability and morphological changes through downregulation and localization shift of the tight junction protein occludin. PMID:21977944

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

    PubMed

    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.

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

    PubMed Central

    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

  20. Depletion of Caco-2 cell cholesterol disrupts barrier function by altering the detergent solubility and distribution of specific tight-junction proteins

    PubMed Central

    2004-01-01

    In the present study, we have investigated the role of cholesterol in maintaining the barrier properties of the model intestinal cell line Caco-2. We have extracted membrane cholesterol using methyl-β-cyclodextrin and demonstrated that maximally, methyl-β-cyclodextrin lowered cell cholesterol levels by 40–45%. Depletion of cell cholesterol was accompanied by an 80–90% decrease in monolayer transepithelial electrical resistance and a significant increase in the paracellular permeability of dextrans of 4, 10 and 40 kDa. The increase in dextran permeability was most pronounced for the two lower molecular mass species. In addition to the decline in the barrier properties of the monolayers, extraction of cell cholesterol produced an increase in the Triton X-100 solubility of claudin 3, claudin 4 and occludin, and the loss of all three proteins from the plasma membrane (tight junctions). In contrast, removal of cholesterol had no detectable influence on the detergent solubility or morphological distribution of claudin 1. These results indicate that membrane cholesterol is a critical factor in maintaining the barrier property of epithelial monolayers. More specifically, cholesterol appears to stabilize the association of certain proteins with the tight junctions. PMID:15500448

  1. Enabled (Xena) regulates neural plate morphogenesis, apical constriction, and cellular adhesion required for neural tube closure in Xenopus

    PubMed Central

    Roffers-Agarwal, Julaine; Xanthos, Jennifer B.; Kragtorp, Katherine A.; Miller, Jeffrey R.

    2008-01-01

    Regulation of cellular adhesion and cytoskeletal dynamics is essential for neurulation, though it remains unclear how these two processes are coordinated. Members of the Ena/VASP family of proteins are localized to sites of cellular adhesion and actin dynamics and lack of two family members, Mena and VASP, in mice results in failure of neural tube closure. The precise mechanism by which Ena/VASP proteins regulate this process, however, is not understood. In this report, we show that Xenopus Ena (Xena) is localized to apical adhesive junctions of neuroepithelial cells during neurulation and that Xena knockdown disrupts cell behaviors integral to neural tube closure. Changes in the shape of the neural plate as well as apical constriction within the neural plate are perturbed in Xena knockdown embryos. Additionally, we demonstrate that Xena is essential for cell-cell adhesion. These results demonstrate that Xena plays an integral role in coordinating the regulation of cytoskeletal dynamics and cellular adhesion during neurulation in Xenopus. PMID:18201691

  2. Apical membrane antigen 1 mediates apicomplexan parasite attachment but is dispensable for host cell invasion

    PubMed Central

    Bargieri, Daniel Y.; Andenmatten, Nicole; Lagal, Vanessa; Thiberge, Sabine; Whitelaw, Jamie A.; Tardieux, Isabelle; Meissner, Markus; Ménard, Robert

    2013-01-01

    Apicomplexan parasites invade host cells by forming a ring-like junction with the cell surface and actively sliding through the junction inside an intracellular vacuole. Apical membrane antigen 1 is conserved in apicomplexans and a long-standing malaria vaccine candidate. It is considered to have multiple important roles during host cell penetration, primarily in structuring the junction by interacting with the rhoptry neck 2 protein and transducing the force generated by the parasite motor during internalization. Here, we generate Plasmodium sporozoites and merozoites and Toxoplasma tachyzoites lacking apical membrane antigen 1, and find that the latter two are impaired in host cell attachment but the three display normal host cell penetration through the junction. Therefore, apical membrane antigen 1, rather than an essential invasin, is a dispensable adhesin of apicomplexan zoites. These genetic data have implications on the use of apical membrane antigen 1 or the apical membrane antigen 1–rhoptry neck 2 interaction as targets of intervention strategies against malaria or other diseases caused by apicomplexans. PMID:24108241

  3. Early Activation of MAPK p44/42 Is Partially Involved in DON-Induced Disruption of the Intestinal Barrier Function and Tight Junction Network

    PubMed Central

    Springler, Alexandra; Hessenberger, Sabine; Schatzmayr, Gerd; Mayer, Elisabeth

    2016-01-01

    Deoxynivalenol (DON), produced by the plant pathogens Fusarium graminearum and Fusarium culmorum, is one of the most common mycotoxins, contaminating cereal and cereal-derived products. Although worldwide contamination of food and feed poses health threats to humans and animals, pigs are particularly susceptible to this mycotoxin. DON derivatives, such as deepoxy-deoxynivalenol (DOM-1), are produced by bacterial transformation of certain intestinal bacteria, which are naturally occurring or applied as feed additives. Intestinal epithelial cells are the initial barrier against these food- and feed-borne toxins. The present study confirms DON-induced activation of MAPK p44/42 and inhibition of p44/42 by MAPK-inhibitor U0126 monoethanolate. Influence of DON and DOM-1 on transepithelial electrical resistance (TEER), viability and expression of seven tight junction proteins (TJ), as well as the potential of U0126 to counteract DON-induced effects, was assessed. While DOM-1 showed no effect, DON significantly reduced TEER of differentiated IPEC-J2 and decreased expression of claudin-1 and -3, while leaving claudin-4; ZO-1, -2, and -3 and occludin unaffected. Inhibition of p44/42 counteracted DON-induced TEER decrease and restored claudin-3, but not claudin-1 expression. Therefore, effects of DON on TEER and claudin-3 are at least partially p44/42 mediated, while effects on viability and claudin-1 are likely mediated via alternative pathways. PMID:27618100

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

    PubMed

    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. FSGS3/CD2AP is a barbed-end capping protein that stabilizes actin and strengthens adherens junctions.

    PubMed

    Tang, Vivian W; Brieher, William M

    2013-12-09

    By combining in vitro reconstitution biochemistry with a cross-linking approach, we have identified focal segmental glomerulosclerosis 3/CD2-associated protein (FSGS3/CD2AP) as a novel actin barbed-end capping protein responsible for actin stability at the adherens junction. FSGS3/CD2AP colocalizes with E-cadherin and α-actinin-4 at the apical junction in polarized Madin-Darby canine kidney (MDCK) cells. Knockdown of FSGS3/CD2AP compromised actin stability and decreased actin accumulation at the adherens junction. Using a novel apparatus to apply mechanical stress to cell-cell junctions, we showed that knockdown of FSGS3/CD2AP compromised adhesive strength, resulting in tearing between cells and disruption of barrier function. Our results reveal a novel function of FSGS3/CD2AP and a previously unrecognized role of barbed-end capping in junctional actin dynamics. Our study underscores the complexity of actin regulation at cell-cell contacts that involves actin activators, inhibitors, and stabilizers to control adhesive strength, epithelial behavior, and permeability barrier integrity.

  6. Polychlorinated biphenyls impair blood-brain barrier integrity via disruption of tight junction proteins in cerebrum, cerebellum and hippocampus of female Wistar rats: neuropotential role of quercetin.

    PubMed

    Selvakumar, K; Prabha, R Lakshmi; Saranya, K; Bavithra, S; Krishnamoorthy, G; Arunakaran, J

    2013-07-01

    Polychlorinated biphenyls (PCBs) comprise a ubiquitous class of toxic substances associated with carcinogenic and tumor-promoting effects as well as neurotoxic properties. Reactive oxygen species, which is produced from PCBs, alters blood-brain barrier (BBB) integrity, which is paralleled by cytoskeletal rearrangements and redistribution and disappearance of tight junction proteins (TJPs) like claudin-5 and occludin. Quercetin, a potent antioxidant present in onion and other vegetables, appears to protect brain cells against oxidative stress, a tissue-damaging process associated with Alzheimer's and other neurodegenerative disorders. The aim of this study is to analyze the role of quercetin on oxidative stress markers and transcription of transmembrane and cytoplasmic accessory TJPs on cerebrum, cerebellum and hippocampus of female rats exposed to PCBs. Rats were divided into the following four groups. Group I: received only vehicle (corn oil) intraperitoneally (i.p.); group II: received Aroclor 1254 at a dose of 2 mg/kg body weight (bwt)/day (i.p); group III: received Aroclor 1254 (i.p.) and simultaneously quercetin 50 mg/kg bwt/day through gavage and group IV: received quercetin alone gavage. From the experiment, the levels of hydrogen peroxide, lipid peroxidation and thiobarbituric acid reactive substances were observed to increase significantly in cerebrum, cerebellum and hippocampus as 50%, 25% and 20%, respectively, after exposure to PCB, and the messenger RNA expression of TJP in rats exposed to PCBs is decreased and is retrieved to the normal level simultaneously in quercetin-treated rats. Hence, quercetin can be used as a preventive medicine to PCBs exposure and prevents neurodegenerative disorders.

  7. Moderate Hypoxia Followed by Reoxygenation Results in Blood-Brain Barrier Breakdown via Oxidative Stress-Dependent Tight-Junction Protein Disruption

    PubMed Central

    Zehendner, Christoph M.; Librizzi, Laura; Hedrich, Jana; Bauer, Nina M.; Angamo, Eskedar A.; de Curtis, Marco; Luhmann, Heiko J.

    2013-01-01

    Re-canalization of cerebral vessels in ischemic stroke is pivotal to rescue dysfunctional brain areas that are exposed to moderate hypoxia within the penumbra from irreversible cell death. Goal of the present study was to evaluate the effect of moderate hypoxia followed by reoxygenation (MHR) on the evolution of reactive oxygen species (ROS) and blood-brain barrier (BBB) integrity in brain endothelial cells (BEC). BBB integrity was assessed in BEC in vitro and in microvessels of the guinea pig whole brain in situ preparation. Probes were exposed to MHR (2 hours 67-70 mmHg O2, 3 hours reoxygenation, BEC) or towards occlusion of the arteria cerebri media (MCAO) with or without subsequent reperfusion in the whole brain preparation. In vitro BBB integrity was evaluated using trans-endothelial electrical resistance (TEER) and transwell permeability assays. ROS in BEC were evaluated using 2′,7′-dichlorodihydrofluorescein diacetate (DCF), MitoSox and immunostaining for nitrotyrosine. Tight-junction protein (TJ) integrity in BEC, stainings for nitrotyrosine and FITC-albumin extravasation in the guinea pig brain preparation were assessed by confocal microscopy. Diphenyleneiodonium (DPI) was used to investigate NADPH oxidase dependent ROS evolution and its effect on BBB parameters in BEC. MHR impaired TJ proteins zonula occludens 1 (ZO-1) and claudin 5 (Cl5), decreased TEER, and significantly increased cytosolic ROS in BEC. These events were blocked by the NADPH oxidase inhibitor DPI. MCAO with or without subsequent reoxygenation resulted in extravasation of FITC-albumin and ROS generation in the penumbra region of the guinea pig brain preparation and confirmed BBB damage. BEC integrity may be impaired through ROS in MHR on the level of TJ and the BBB is also functionally impaired in moderate hypoxic conditions followed by reperfusion in a complex guinea pig brain preparation. These findings suggest that the BBB is susceptible towards MHR and that ROS play a key role in

  8. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon Sheng; Zettl, Alexander Karlwalter

    2003-01-01

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  9. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon; Zettl, Alexander Karlwalte

    2004-12-28

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  10. F5-peptide induces aspermatogenesis by disrupting organization of actin- and microtubule-based cytoskeletons in the testis

    PubMed Central

    Gao, Ying; Mruk, Dolores D.; Lui, Wing-yee; Lee, Will M.; Cheng, C. Yan

    2016-01-01

    During the release of sperm at spermiation, a biologically active F5-peptide, which can disrupt the Sertoli cell tight junction (TJ) permeability barrier, is produced at the site of the degenerating apical ES (ectoplasmic specialization). This peptide coordinates the events of spermiation and blood-testis barrier (BTB) remodeling at stage VIII of the epithelial cycle, creating a local apical ES-BTB axis to coordinate cellular events across the epithelium. The mechanism(s) by which F5-peptide perturbs BTB restructuring, and its involvement in apical ES dynamics remain unknown. F5-peptide, besides perturbing BTB integrity, was shown to induce germ cell release from the epithelium following its efficient in vivo overexpression in the testis. Overexpression of F5-peptide caused disorganization of actin- and microtubule (MT)-based cytoskeletons, mediated by altering the spatiotemporal expression of actin binding/regulatory proteins in the seminiferous epithelium. F5-peptide perturbed the ability of actin microfilaments and/or MTs from converting between their bundled and unbundled/defragmented configuration, thereby perturbing adhesion between spermatids and Sertoli cells. Since apical ES and basal ES/BTB are interconnected through the underlying cytoskeletal networks, this thus provides an efficient and novel mechanism to coordinate different cellular events across the epithelium during spermatogenesis through changes in the organization of actin microfilaments and MTs. These findings also illustrate the potential of F5-peptide being a male contraceptive peptide for men. PMID:27611949

  11. Liver kinase B1 regulates hepatocellular tight junction distribution and function in vivo

    PubMed Central

    Tietgens, Amber J.; Van Itallie, Christina M.; Vitale‐Cross, Lynn; Jarnik, Michal; Harding, Olivia J.; Anderson, James M.; Gutkind, J. Silvio; Weigert, Roberto; Arias, Irwin M.

    2016-01-01

    Liver kinase B1 (LKB1) and its downstream effector AMP‐activated protein kinase (AMPK) play critical roles in polarity establishment by regulating membrane trafficking and energy metabolism. In collagen sandwich‐cultured hepatocytes, loss of LKB1 or AMPK impaired apical ABCB11 (Bsep) trafficking and bile canalicular formation. In the present study, we used liver‐specific (albumin‐Cre) LKB1 knockout mice (LKB1−/−) to investigate the role of LKB1 in the maintenance of functional tight junction (TJ) in vivo. Transmission electron microscopy examination revealed that hepatocyte apical membrane with microvilli substantially extended into the basolateral domain of LKB1−/− livers. Immunofluorescence studies revealed that loss of LKB1 led to longer and wider canalicular structures correlating with mislocalization of the junctional protein, cingulin. To test junctional function, we used intravital microscopy to quantify the transport kinetics of 6‐carboxyfluorescein diacetate (6‐CFDA), which is processed in hepatocytes into its fluorescent derivative 6‐carboxyfluorescein (6‐CF) and secreted into the canaliculi. In LKB1−/− mice, 6‐CF remained largely in hepatocytes, canalicular secretion was delayed, and 6‐CF appeared in the blood. To test whether 6‐CF was transported through permeable TJ, we intravenously injected low molecular weight (3 kDa) dextran in combination with 6‐CFDA. In wild‐type mice, 3 kDa dextran remained in the vasculature, whereas it rapidly appeared in the abnormal bile canaliculi in LKB1−/− mice, confirming that junctional disruption resulted in paracellular exchange between the blood stream and the bile canaliculus. Conclusion: LKB1 plays a critical role in regulating the maintenance of TJ and paracellular permeability, which may explain how various drugs, chemicals, and metabolic states that inhibit the LKB1/AMPK pathway result in cholestasis. (Hepatology 2016;64:1317‐1329) PMID:27396550

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

    PubMed

    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.

  13. Disruption of paracellular sealing is an early event in acute caerulein-pancreatitis.

    PubMed

    Schmitt, Marcus; Klonowski-Stumpe, Hanne; Eckert, Mario; Lüthen, Reinhard; Häussinger, Dieter

    2004-03-01

    Caerulein-induced pancreatitis is a widely used experimental model for studies on acute pancreatitis, however, the molecular mechanisms underlying pancreatitis in response to caerulein hyperstimulation are incompletely understood. We therefore studied early effects of caerulein on tight junctional integrity. Mice were injected with the cholecystokinin analogue caerulein (50microg/kg BW/h) to induce pancreatitis. In pancreatic tissue occludin, claudin 1, zonula occludens protein 1 (ZO-1) were stained immunohistochemically and F-actin was visualized with phalloidin-TRITC. Stained sections and isolated acini were studied by confocal laser scanning microscopy. Under control conditions occludin, claudin1, ZO-1, and F-actin showed a linear staining pattern delineating the apical membranes of intralobular duct cells and of acinar cells. While in vitro caerulein hyperstimulation induced within 10 minutes disassembly of both occludin and ZO-1, in vivo caerulein hyperstimulation induced disassembly of occludin and claudin1 but not of ZO-1 from the tight junctions. Subsequent progressive disruption of ZO-1 was detected in a time dependent manner. Disruption of the transmembrane tight junction proteins occludin and claudin1 is an early event of caerulein hyperstimulation and may allow evasion of noxious luminal content into the interstitium, which may augment edema formation in acute pancreatitis.

  14. Loss of Gα12/13 exacerbates apical area dependence of actomyosin contractility

    PubMed Central

    Xie, Shicong; Mason, Frank M.; Martin, Adam C.

    2016-01-01

    During development, coordinated cell shape changes alter tissue shape. In the Drosophila ventral furrow and other epithelia, apical constriction of hundreds of epithelial cells folds the tissue. Genes in the Gα12/13 pathway coordinate collective apical constriction, but the mechanism of coordination is poorly understood. Coupling live-cell imaging with a computational approach to identify contractile events, we discovered that differences in constriction behavior are biased by initial cell shape. Disrupting Gα12/13 exacerbates this relationship. Larger apical area is associated with delayed initiation of contractile pulses, lower apical E-cadherin and F-actin levels, and aberrantly mobile Rho-kinase structures. Our results suggest that loss of Gα12/13 disrupts apical actin cortex organization and pulse initiation in a size-dependent manner. We propose that Gα12/13 robustly organizes the apical cortex despite variation in apical area to ensure the timely initiation of contractile pulses in a tissue with heterogeneity in starting cell shape. PMID:27489340

  15. Josephson junction

    DOEpatents

    Wendt, J.R.; Plut, T.A.; Martens, J.S.

    1995-05-02

    A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material. 10 figs.

  16. Josephson junction

    DOEpatents

    Wendt, Joel R.; Plut, Thomas A.; Martens, Jon S.

    1995-01-01

    A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material.

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

    PubMed Central

    Martin, Adam C.; Goldstein, Bob

    2014-01-01

    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. PMID:24803648

  18. A proposed route to independent measurements of tight junction conductance at discrete cell junctions

    PubMed Central

    Zhou, Lushan; Zeng, Yuhan; Baker, Lane A; Hou, Jianghui

    2015-01-01

    Direct recording of tight junction permeability is of pivotal importance to many biologic fields. Previous approaches bear an intrinsic disadvantage due to the difficulty of separating tight junction conductance from nearby membrane conductance. Here, we propose the design of Double whole-cell Voltage Clamp - Ion Conductance Microscopy (DVC-ICM) based on previously demonstrated potentiometric scanning of local conductive pathways. As proposed, DVC-ICM utilizes two coordinated whole-cell patch-clamps to neutralize the apical membrane current during potentiometric scanning, which in models described here will profoundly enhance the specificity of tight junction recording. Several potential pitfalls are considered, evaluated and addressed with alternative countermeasures. PMID:26716077

  19. Gap Junctions

    PubMed Central

    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

  20. Defects in the adherens junction complex (E-cadherin/ β-catenin) in inflammatory bowel disease.

    PubMed

    Mehta, Shameer; Nijhuis, Anke; Kumagai, Tomoko; Lindsay, James; Silver, Andrew

    2015-06-01

    The epithelial monolayer of the intestine is a selective barrier permitting nutrient and electrolyte absorption yet acting to protect the underlying tissue compartments and cellular components from attack and infiltration by antigens, bacteria and bacterial products present in the lumen. Disruption of this barrier has been associated with inflammatory bowel disease (IBD). The adherens junction (AJ), together with tight junctions (TJ) and desmosomes, form an apical junction complex that controls epithelial cell-to-cell adherence and barrier function as well as regulation of the actin cytoskeleton, intracellular signalling pathways and transcriptional regulation. Numerous studies and reviews highlight the responses of TJs to physiological and pathological stimuli. By comparison, the response of AJ proteins, and the subsequent consequences for barrier function, when exposed to the IBD inflammatory milieu, is less well studied. In this review, we will highlight the roles and responses of the AJ proteins in IBD and provide suggestions for future studies. We will also consider recently proposed therapeutic strategies to preserve or restore epithelial barrier functions to prevent and treat IBD.

  1. Nectin and junctional adhesion molecule are critical cell adhesion molecules for the apico-basal alignment of adherens and tight junctions in epithelial cells.

    PubMed

    Yamada, Tomohiro; Kuramitsu, Kaori; Rikitsu, Etsuko; Kurita, Souichi; Ikeda, Wataru; Takai, Yoshimi

    2013-11-01

    Tight junctions (TJs) and adherens junctions (AJs) form an apical junctional complex at the apical side of the lateral membranes of epithelial cells, in which TJs are aligned at the apical side of AJs. Many cell adhesion molecules (CAMs) and cell polarity molecules (CPMs) cooperatively regulate the formation of the apical junctional complex, but the mechanism for the alignment of TJs at the apical side of AJs is not fully understood. We developed a cellular system with which epithelial-like TJs and AJs were reconstituted in fibroblasts and analyzed the cooperative roles of CAMs and CPMs. We exogenously expressed various combinations of CAMs and CPMs in fibroblasts that express negligible amounts of these molecules endogenously. In these cells, the nectin-based cell-cell adhesion was formed at the apical side of the junctional adhesion molecule (JAM)-based cell-cell adhesion, and cadherin and claudin were recruited to the nectin-3- and JAM-based cell-cell adhesion sites to form AJ-like and TJ-like domains, respectively. This inversed alignment of the AJ-like and TJ-like domains was reversed by complementary expression of CPMs Par-3, atypical protein kinase C, Par-6, Crb3, Pals1 and Patj. We describe the cooperative roles of these CAMs and CPMs in the apico-basal alignment of TJs and AJs in epithelial cells.

  2. Defective calmodulin-dependent rapid apical endocytosis in zebrafish sensory hair cell mutants.

    PubMed

    Seiler, C; Nicolson, T

    1999-11-15

    Vertebrate mechanosensory hair cells contain a narrow "pericuticular" zone which is densely populated with small vesicles between the cuticular plate and cellular junctions near the apical surface. The presence of many cytoplasmic vesicles suggests that the apical surface of hair cells has a high turnover rate. The significance of intense membrane trafficking at the apical surface is not known. Using a marker of endocytosis, the styryl dye FM1-43, this report shows that rapid apical endocytosis in zebrafish lateral line sensory hair cells is calcium and calmodulin dependent and is partially blocked by the presence of amiloride and dihydrostreptomycin, known inhibitors of mechanotransduction channels. As seen in lateral line hair cells, sensory hair cells within the larval otic capsule also exhibit rapid apical endocytosis. Defects in internalization of the dye in both lateral line and inner ear hair cells were found in five zebrafish auditory/vestibular mutants: sputnik, mariner, orbiter, mercury, and skylab. In addition, lateral line hair cells in these mutants were not sensitive to prolonged exposure to streptomycin, which is toxic to hair cells. The presence of endocytic defects in the majority of zebrafish mechanosensory mutants points to a important role of apical endocytosis in hair cell function.

  3. POST-TRAUMATIC APICAL LEFT VENTRICULAR ANEURYSM IN A PATIENT WITH LEFT VENTRICULAR APICAL-ABDOMINAL AORTIC CONDUIT: CASE PRESENTATION

    PubMed Central

    Ugorji, Clement C.; Cooley, Denton A.; Norman, John C.

    1979-01-01

    A patient with a small aortic annulus had an apico-aortic conduit implanted for aortic stenosis approximately three years before being admitted to our institution. Four months after sustaining a steering wheel injury to the chest, he developed chest pain and palpitations. X-ray films and left ventriculograms revealed a large apical aneurysm of unknown duration. At surgery, it was noted that the proximal portion of the conduit had been sewn directly to the myocardium without the use of a rigid or soft apical outlet prosthesis incorporating a sewing ring. The aneurysm was resected along with a small proximal segment of the conduit graft. A polished Pyrolite® rigid inlet tube with a sewing ring and graft extension was inserted into the residual left ventricular apex, and continuity was reestablished with the abdominal segment of the conduit. It is postulated that the aneurysm was caused by either the direct anastomosis of the fabric graft to the apical myocardium at the original operation (with subsequent disruption and aneurysm formation prior to the steering wheel injury), or was the result of fixation of the heart at the diaphragm by the conduit, with increased vulnerability to deceleration injury at the direct left ventricular apex myocardium-fabric graft site. Images PMID:15216296

  4. Disruptive Students.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany.

    This paper attempts to develop guidelines relating to the problem of disruptive pupils in the classroom. A disruptive student is defined as one who interferes with the learning process. He is often male, physically aggressive, verbally hostile, over-age and frequently absent. The study examines the overlap between disruptive behavior and emotional…

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

    PubMed

    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.

  6. Constitutive apical membrane recycling in Aplysia enterocytes.

    PubMed

    Keeton, Robert Aaron; Runge, Steven William; Moran, William Michael

    2004-11-01

    In Aplysia californica enterocytes, alanine-stimulated Na+ absorption increases both apical membrane exocytosis and fractional capacitance (fCa; a measure of relative apical membrane surface area). These increases are thought to reduce membrane tension during periods of nutrient absorption that cause the enterocytes to swell osmotically. In the absence of alanine, exocytosis and fCa are constant. These findings imply equal rates of constitutive endocytosis and exocytosis and constitutive recycling of the apical plasma membrane. Thus, the purpose of this study was to confirm and determine the relative extent of constitutive apical membrane recycling in Aplysia enterocytes. Biotinylated lectins are commonly used to label plasma membranes and to investigate plasma membrane recycling. Of fourteen biotinylated lectins tested, biotinylated wheat germ agglutinin (bWGA) bound preferentially to the enterocytes apical surface. Therefore, we used bWGA, avidin D (which binds tightly to biotin), and the UV fluorophore 7-amino-4-methylcoumarin-3-acetic acid (AMCA)-conjugated avidin D to assess the extent of constitutive apical membrane recycling. A temperature-dependent (20 vs. 4 degrees C) experimental protocol employed the use of two tissues from each of five snails and resulted in a approximately 60% difference in apical surface fluorescence intensity. Because the extent of membrane recycling is proportional to the difference in surface fluorescence intensity, this difference reveals a relatively high rate of constitutive apical membrane recycling in Aplysia enterocytes.

  7. Apical and basolateral transferrin receptors in polarized BeWo cells recycle through separate endosomes

    PubMed Central

    1991-01-01

    Contrary to most other epithelia, trophoblasts in the human placenta, which form the physical barrier between the fetal and the maternal blood circulation, express high numbers of transferrin receptors on their apical cell surface. This study describes the establishment of a polarized trophoblast-like cell line BeWo, which exhibit a high expression of transferrin receptors on the apex of the cells. Cultured on permeable filter supports, BeWo cells formed a polarized monolayer with microvilli on their apical cell surface. Across the monolayer a transepithelial resistance developed of approximately 600 omega.cm2 within 4 d. Depletion of Ca2+ from the medium decreased the resistance to background levels, showing its dependence on the integrity of tight junctions. Within the same period of time the secretion of proteins became polarized. In addition, the compositions of integral membrane proteins at the apical and basolateral plasma membrane domains were distinct as determined by domain-selective iodination. Similar to placental trophoblasts, binding of 125I-labeled transferrin to BeWo monolayers revealed that the transferrin receptor was expressed at both plasma membrane domains. Apical and basolateral transferrin receptors were found in a 1:2 surface ratio and exhibited identical dissociation constants and molecular weights. After uptake, transferrin recycled predominantly to the domain of administration, indicating separate recycling pathways from the apical and basolateral domain. This was confirmed by using diaminobenzidine cytochemistry, a technique by which colocalization of endocytosed 125I-labeled and HRP-conjugated transferrin can be monitored. No mixing of the two types of ligands was observed, when both ligands were simultaneously internalized for 10 or 60 min from opposite domains, demonstrating that BeWo cells possess separate populations of apical and basolateral early endosomes. In conclusion, the trophoblast-like BeWo cell line can serve as a unique

  8. Factors affecting apical leakage assessment.

    PubMed

    Karagöz-Küçükay, I; Küçükay, S; Bayirli, G

    1993-07-01

    This study was conducted to evaluate the influence of immediate versus delayed immersion time, and passive dye immersion versus centrifuged dye on apical leakage measurements. Eighty-four extracted human teeth with single straight canals were instrumented and divided into four experimental groups of 20 teeth each plus 2 negative and 2 positive controls. Low-temperature injection thermoplasticized gutta-percha and sealer were used to obturate the root canals. In groups A and B the filling materials were allowed to set for 72 h before the teeth were placed in India ink. In groups C and D the teeth were placed in India ink immediately after obturation. Also, in groups B and D the teeth were centrifuged in India ink for 20 min at 3,000 rpm before being immersed in ink. After 72 h in India ink, the teeth were cleared, and the linear extent of ink penetration was measured with a stereomicroscope. Statistical analysis of the data revealed no significant difference in leakage among the experimental groups whether the teeth were immersed in ink immediately after obturation or after setting of the filling materials for 72 h, and whether or not the teeth were centrifuged in ink prior to immersion.

  9. Apical tuft input efficacy in layer 5 pyramidal cells from rat visual cortex

    PubMed Central

    Rhodes, Paul A; Llinás, Rodolfo R

    2001-01-01

    at a single critical point, the apex of the distal trunk, and so was relatively undiminished by the background. Further, once initiation at the apex occurred, background had little effect on inward propagation along the trunk.We conclude that synaptic input to the apical tuft of layer 5 cells may be unexpectedly effective in triggering cell firing in vivo. The advantage in efficacy was not dependent upon the characteristics of tuft membrane excitability, but rather stemmed from the geometry of the tuft and its junction with the distal apical trunk. The efficacy of tuft input was, however, critically dependent upon inward propagation, suggesting that modulation of membrane currents which affect propagation in the apical trunk might sensitively control the efficacy of tuft input. PMID:11579167

  10. ADAM10 Is Involved in Cell Junction Assembly in Early Porcine Embryo Development

    PubMed Central

    Kwon, Jeongwoo; Jeong, Sung-min; Choi, Inchul; Kim, Nam-Hyung

    2016-01-01

    ADAM10 (A Disintegrin and Metalloprotease domain-containing protein 10) is a cell surface protein with a unique structure possessing both potential adhesion and protease domains. However, the role of ADAM10 in preimplantation stage embryos is not clear. In this study, we examined the expression patterns and functional roles of ADAM10 in porcine parthenotes during preimplantation development. The transcription level of ADAM10 dramatically increased from the morula stage onward. Immunostaining revealed that ADAM10 was present in both the nucleus and cytoplasm in early cleavage stage embryos, and localized to the apical region of the outer cells in morula and blastocyst embryos. Knockdown (KD) of ADAM10 using double strand RNA did not alter preimplantation embryo development until morula stage, but resulted in significantly reduced development to blastocyst stage. Moreover, the KD blastocyst showed a decrease in gene expression of adherens and tight junction (AJ/TJ), and an increase in trophectoderm TJ permeability by disrupting TJ assembly. Treatment with an ADAM10 specific chemical inhibitor, GI254023X, at the morula stage also inhibited blastocyst development and led to disruption of TJ assembly. An in situ proximity ligation assay demonstrated direct interaction of ADAM10 with coxsackie virus and adenovirus receptor (CXADR), supporting the involvement of ADAM10 in TJ assembly. In conclusion, our findings strongly suggest that ADADM10 is important for blastocyst formation rather than compaction, particularly for TJ assembly and stabilization in preimplantation porcine parthenogenetic development. PMID:27043020

  11. ADAM10 Is Involved in Cell Junction Assembly in Early Porcine Embryo Development.

    PubMed

    Kwon, Jeongwoo; Jeong, Sung-min; Choi, Inchul; Kim, Nam-Hyung

    2016-01-01

    ADAM10 (A Disintegrin and Metalloprotease domain-containing protein 10) is a cell surface protein with a unique structure possessing both potential adhesion and protease domains. However, the role of ADAM10 in preimplantation stage embryos is not clear. In this study, we examined the expression patterns and functional roles of ADAM10 in porcine parthenotes during preimplantation development. The transcription level of ADAM10 dramatically increased from the morula stage onward. Immunostaining revealed that ADAM10 was present in both the nucleus and cytoplasm in early cleavage stage embryos, and localized to the apical region of the outer cells in morula and blastocyst embryos. Knockdown (KD) of ADAM10 using double strand RNA did not alter preimplantation embryo development until morula stage, but resulted in significantly reduced development to blastocyst stage. Moreover, the KD blastocyst showed a decrease in gene expression of adherens and tight junction (AJ/TJ), and an increase in trophectoderm TJ permeability by disrupting TJ assembly. Treatment with an ADAM10 specific chemical inhibitor, GI254023X, at the morula stage also inhibited blastocyst development and led to disruption of TJ assembly. An in situ proximity ligation assay demonstrated direct interaction of ADAM10 with coxsackie virus and adenovirus receptor (CXADR), supporting the involvement of ADAM10 in TJ assembly. In conclusion, our findings strongly suggest that ADADM10 is important for blastocyst formation rather than compaction, particularly for TJ assembly and stabilization in preimplantation porcine parthenogenetic development.

  12. APIC: A generic interface for sequencing projects

    SciTech Connect

    Bisson, G.; Garreau, A.

    1995-12-31

    In this paper, we describe the APIC graphical interface that aims at displaying the results produced by the genomic sequence analysis methods and at helping a comparison of these results. The major feature of APIC lies in its genericity. As a matter of fact, this interface can obviously be used to visualize genetic or physical maps but it also able to display other kinds of information such as curves or pictures. On the one hand, APIC provides the biologist who builds a new sequence analysis method with a standard interface allowing to display his results. Thus, he can avoid implementing a specific visualization tool. On the other hand, even when the methods already have their own interfaces, using APIC has the advantage of giving a homogeneous way to compare several results coming from different analysis tools. Moreover, it provides some powerful functions for navigating and browsing into the results.

  13. Advanced Pointing Imaging Camera (APIC) Concept

    NASA Astrophysics Data System (ADS)

    Park, R. S.; Bills, B. G.; Jorgensen, J.; Jun, I.; Maki, J. N.; McEwen, A. S.; Riedel, E.; Walch, M.; Watkins, M. M.

    2016-10-01

    The Advanced Pointing Imaging Camera (APIC) concept is envisioned as an integrated system, with optical bench and flight-proven components, designed for deep-space planetary missions with 2-DOF control capability.

  14. Rhinovirus Disrupts the Barrier Function of Polarized Airway Epithelial Cells

    PubMed Central

    Sajjan, Umadevi; Wang, Qiong; Zhao, Ying; Gruenert, Dieter C.; Hershenson, Marc B.

    2008-01-01

    Rationale: Secondary bacterial infection following rhinovirus (RV) infection has been recognized in chronic obstructive pulmonary disease. Objectives: We sought to understand mechanisms by which RV infection facilitates secondary bacterial infection. Methods: Primary human airway epithelial cells grown at air–liquid interface and human bronchial epithelial (16HBE14o-) cells grown as polarized monolayers were infected apically with RV. Transmigration of bacteria (nontypeable Haemophilus influenzae and others) was assessed by colony counting and transmission electron microscopy. Transepithelial resistance (RT) was measured by using a voltmeter. The distribution of zona occludins (ZO)-1 was determined by immunohistochemistry and immunoblotting. Measurements and Main Results: Epithelial cells infected with RV showed 2-log more bound bacteria than sham-infected cultures, and bacteria were recovered from the basolateral media of RV- but not sham-infected cells. Infection of polarized airway epithelial cell cultures with RV for 24 hours caused a significant decrease in RT without causing cell death or apoptosis. Ultraviolet-treated RV did not decrease RT, suggesting a requirement for viral replication. Reduced RT was associated with increased paracellular permeability, as determined by flux of fluorescein isothiocyanate (FITC)-inulin. Neutralizing antibodies to tumor necrosis factor (TNF)-α, IFN-γ and IL-1β reversed corresponding cytokine-induced reductions in RT but not that induced by RV, indicating that the RV effect is independent of these proinflammatory cytokines. Confocal microscopy and immunoblotting revealed the loss of ZO-1 from tight junction complexes in RV-infected cells. Intranasal inoculation of mice with RV1B also caused the loss of ZO-1 from the bronchial epithelium tight junctions in vivo. Conclusions: RV facilitates binding, translocation, and persistence of bacteria by disrupting airway epithelial barrier function. PMID:18787220

  15. Apical sorting of bovine enteropeptidase does not involve detergent-resistant association with sphingolipid-cholesterol rafts.

    PubMed

    Zheng, X; Lu, D; Sadler, J E

    1999-01-15

    Enteropeptidase is a heterodimeric type II membrane protein of the brush border of duodenal enterocytes. In this location, enteropeptidase cleaves and activates trypsinogen, thereby initiating the activation of other intestinal digestive enzymes. Recombinant bovine enteropeptidase was sorted directly to the apical surface of polarized Madin-Darby canine kidney cells. Replacement of the cytoplasmic and signal anchor domains with a cleavable signal peptide (mutant proenteropeptidase lacking the amino-terminal signal anchor domain (dSA-BEK)) caused apical secretion. The additional amino-terminal deletion of a mucin-like domain (HL-BEK) resulted in secretion both apically and basolaterally. Further deletion of the noncatalytic heavy chain (L-BEK) resulted in apical secretion. Thus enteropeptidase appears to have at least three distinct sorting signals as follows: the light chain (L-BEK) directs apical sorting, addition of most of the heavy chain (HL-BEK) inhibits apical sorting, and addition of the mucin-like domain (dSA-BEK) restores apical sorting. Inhibition of N-linked glycosylation with tunicamycin or disruption of microtubules with colchicine caused L-BEK to be secreted equally into apical and basolateral compartments, whereas brefeldin A caused basolateral secretion of L-BEK. Full-length BEK was not found in detergent-resistant raft domains of Madin-Darby canine kidney cells or baby hamster kidney cells. These results suggest apical sorting of enteropeptidase depends on N-linked glycosylation of the serine protease domain and an amino-terminal segment that includes an O-glycosylated mucin-like domain and three potential N-glycosylation sites. In contrast to many apically targeted proteins, enteropeptidase does not form detergent-resistant associations with sphingolipid-cholesterol rafts.

  16. Developmental stratification of the mammary epithelium occurs through symmetry-breaking vertical divisions of apically positioned luminal cells.

    PubMed

    Huebner, Robert J; Lechler, Terry; Ewald, Andrew J

    2014-03-01

    Mammary ducts are elongated during development by stratified epithelial structures, known as terminal end buds (TEBs). TEBs exhibit reduced apicobasal polarity and extensive proliferation. A major unanswered question concerns the mechanism by which the simple ductal epithelium stratifies during TEB formation. We sought to elucidate this mechanism using real-time imaging of growth factor-induced stratification in 3D cultures of mouse primary epithelial organoids. We hypothesized that stratification could result from vertical divisions in either the apically positioned luminal epithelial cells or the basally positioned myoepithelial cells. Stratification initiated exclusively from vertical apical cell divisions, both in 3D culture and in vivo. During vertical apical divisions, only the mother cell retained tight junctions and segregated apical membranes. Vertical daughter cells initiated an unpolarized cell population located between the luminal and myoepithelial cells, similar to the unpolarized body cells in the TEB. As stratification and loss of apicobasal polarity are early hallmarks of cancer, we next determined the cellular mechanism of oncogenic stratification. Expression of activated ERBB2 induced neoplastic stratification through analogous vertical divisions of apically positioned luminal epithelial cells. However, ERBB2-induced stratification was accompanied by tissue overgrowth and acute loss of both tight junctions and apical polarity. Expression of phosphomimetic MEK (MEK1DD), a major ERBB2 effector, also induced stratification through vertical apical cell divisions. However, MEK1DD-expressing organoids exhibited normal levels of growth and retained apicobasal polarity. We conclude that both normal and neoplastic stratification are accomplished through receptor tyrosine kinase signaling dependent vertical cell divisions within the luminal epithelial cell layer.

  17. Evaluation of the apical adaptation performance of various root canal instruments

    PubMed Central

    Ceyhanli, K. Tolga; Turkun, Murat; Erdilek, Necdet; Peskersoy, Cem; Kose, Timur

    2013-01-01

    Objective: The aim of this study was to evaluate the apical root canal adaptation performance of various root canal instruments. Materials and Methods: A total of 40 freshly extracted single-rooted mandibular incisors were used in this study. Coroner parts of all teeth were removed from cemento-enamel junction and root canal of each tooth was explored with a size 8 K-file until the tip of the file was just visible at the apex. Working lengths (WLs) were determined as 1 mm short of these measurements. ProTaper, K-file, profile and hedstroem files were inserted into the root canals of 10 teeth to the WL following the flaring of the coronal and middle thirds. Instruments were fixed in the root canals with acrylic resin. The apical 1 mm of each root tip was ground on wet sandpaper to expose the canal and the instrument at the WL and the apical region of each tooth was examined under stereomicroscope. The stereoscopic images of the teeth were digitized and analyzed with software in order to determine the differences between the areas of root canals and file tips. Result data were analyzed using the one-way analysis of variance test (P = 0.05). Results: There were no significant differences between apical file/root canal areas of the evaluated instruments (P > 0.05). Conclusions: None of the evaluated instruments performed a perfect adaptation with the apical root canal surface at the WL in mandibular incisors. Therefore, total removal of the debris from the apical canal surface may not be achieved when these filing instruments are used. PMID:24966727

  18. Myosin-dependent remodeling of adherens junctions protects junctions from Snail-dependent disassembly

    PubMed Central

    Weng, Mo

    2016-01-01

    Although Snail is essential for disassembly of adherens junctions during epithelial–mesenchymal transitions (EMTs), loss of adherens junctions in Drosophila melanogaster gastrula is delayed until mesoderm is internalized, despite the early expression of Snail in that primordium. By combining live imaging and quantitative image analysis, we track the behavior of E-cadherin–rich junction clusters, demonstrating that in the early stages of gastrulation most subapical clusters in mesoderm not only persist, but move apically and enhance in density and total intensity. All three phenomena depend on myosin II and are temporally correlated with the pulses of actomyosin accumulation that drive initial cell shape changes during gastrulation. When contractile myosin is absent, the normal Snail expression in mesoderm, or ectopic Snail expression in ectoderm, is sufficient to drive early disassembly of junctions. In both cases, junctional disassembly can be blocked by simultaneous induction of myosin contractility. Our findings provide in vivo evidence for mechanosensitivity of cell–cell junctions and imply that myosin-mediated tension can prevent Snail-driven EMT. PMID:26754645

  19. Microbiology and treatment of acute apical abscesses.

    PubMed

    Siqueira, José F; Rôças, Isabela N

    2013-04-01

    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.

  20. Microbiology and Treatment of Acute Apical Abscesses

    PubMed Central

    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

  1. Apical aneurysm of Chagas's heart disease.

    PubMed Central

    Oliveira, J S; Mello De Oliveira, J A; Frederigue, U; Lima Filho, E C

    1981-01-01

    A retrospective study of Chagas's heart disease was carried out by a review of necropsy reports with special reference to the lesion known as the apical aneurysm. It was concluded that this lesion was more frequent in men, was unrelated to age, and was unrelated to heart weight. Patients dying of the cardiac consequences of Chagas's cardiomyopathy were more likely to have an apical aneurysm than those whose death was unrelated to the disease but the mode of death (sudden, or with heart failure) was unconnected with its presence. Transillumination from within the ventricle at necropsy was not only useful in demonstrating the aneurysm but also showed areas of myocardial thinning elsewhere. Thrombosis within the lesion was frequent. The aetiology of the apical aneurysm is discussed and it is concluded that while ischaemia, inflammation, thrombosis, and mechanical factors may produce and localise this lesion, the underlying cause is the basic pathogenetic process-parasympathetic nerve cell destruction. Images PMID:7295439

  2. Disruptive Students.

    ERIC Educational Resources Information Center

    Smith, David H., Ed.

    A committee was formed to explore ways of helping school districts develop more effective programs for disruptive students. Committee findings revealed the need for the development of local guidelines to satisfy each school district's needs and for reliable feedback. Therefore, this report reflects efforts to sample various local approaches to the…

  3. Family Disruptions

    MedlinePlus

    ... and Returns Do you or your spouse frequently travel on business? These can be disruptive times for your child and for the family as ... these out-of-town trips. Spend as much time as it takes to explain where you are ... before and during your travels. You need to acknowledge and accept her feelings: " ...

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

    PubMed Central

    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

  5. Enzymatic vitreous disruption.

    PubMed

    Gandorfer, A

    2008-10-01

    Enzymatic vitreous disruption refers to cleaving the vitreoretinal junction by enzymatic means, thereby inducing posterior vitreous detachment (PVD) and liquefaction of the vitreous gel. Several enzymes have been proposed in this respect, including chondroitinase, hyaluronidase, dispase, and plasmin. In an experimental setting, chondroitinase induced PVD and was helpful in removing epiretinal membranes but no further data have been reported yet. Hyaluronidase liquefies the vitreous as demonstrated in a phase III trial in diabetic patients with vitreous haemorrhage. Dispase induces PVD but also causes inner retinal damage and is now used as an animal model of proliferative vitreoretinopathy. Plasmin has the capability of both PVD induction and liquefaction. However, plasmin is highly unstable and not available for clinical use. Microplasmin (ThromboGenics Ltd, Dublin, Ireland) is a truncated form of human plasmin sharing the same catalytic activity like plasmin. Recombinant microplasmin is under clinical investigation in patients with vitreomacular traction. This review article reports on the current knowledge of enzymatic vitreous disruption and discusses details of the enzyme candidates in basic and clinical research terms.

  6. The effect of kiwifruit (Actinidia deliciosa) cysteine protease actinidin on the occludin tight junction network in T84 intestinal epithelial cells.

    PubMed

    Cavic, Milena; Grozdanovic, Milica M; Bajic, Aleksandar; Jankovic, Radmila; Andjus, Pavle R; Gavrovic-Jankulovic, Marija

    2014-10-01

    Actinidin, a kiwifruit cysteine protease, is a marker allergen for genuine sensitization to this food allergen source. Inhalatory cysteine proteases have the capacity for disruption of tight junctions (TJs) enhancing the permeability of the bronchial epithelium. No such properties have been reported for allergenic food proteases so far. The aim was to determine the effect of actinidin on the integrity of T84 monolayers by evaluating its action on the TJ protein occludin. Immunoblot and immunofluorescence were employed for the detection of occludin protein alterations. Gene expression was evaluated by RT-PCR. Breach of occludin network was assessed by measuring transepithelial resistance, blue dextran leakage and passage of allergens from the apical to basolateral compartment. Actinidin exerted direct proteolytic cleavage of occludin; no alteration of occludin gene expression was detected. There was a reduction of occludin staining upon actinidin treatment as a consequence of its degradation and dispersion within the membrane. There was an increase in permeability of the T84 monolayer resulting in reduced transepithelial resistance, blue dextran leakage and passage of allergens actinidin and thaumatin-like protein from the apical to basolateral compartment. Opening of TJs by actinidin may increase intestinal permeability and contribute to the process of sensitization in kiwifruit allergy.

  7. Exercise regulation of intestinal tight junction proteins.

    PubMed

    Zuhl, Micah; Schneider, Suzanne; Lanphere, Katherine; Conn, Carole; Dokladny, Karol; Moseley, Pope

    2014-06-01

    Gastrointestinal distress, such as diarrhoea, cramping, vomiting, nausea and gastric pain are common among athletes during training and competition. The mechanisms that cause these symptoms are not fully understood. The stress of heat and oxidative damage during exercise causes disruption to intestinal epithelial cell tight junction proteins resulting in increased permeability to luminal endotoxins. The endotoxin moves into the blood stream leading to a systemic immune response. Tight junction integrity is altered by the phosphoylation state of the proteins occludin and claudins, and may be regulated by the type of exercise performed. Prolonged exercise and high-intensity exercise lead to an increase in key phosphorylation enzymes that ultimately cause tight junction dysfunction, but the mechanisms are different. The purpose of this review is to (1) explain the function and physiology of tight junction regulation, (2) discuss the effects of prolonged and high-intensity exercise on tight junction permeability leading to gastrointestinal distress and (3) review agents that may increase or decrease tight junction integrity during exercise.

  8. Predictive modelling of ferroelectric tunnel junctions

    NASA Astrophysics Data System (ADS)

    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.

  9. Establishing Apical Patency and its Effect on Endodontic Outcomes

    DTIC Science & Technology

    2012-06-01

    canal space and periodontal ligament. Establishing apical patency is controversial with only 50% of dental programs in the United States teaching the... periodontal ligament (PDL) (1) where a small file can passively continue through the apical foramen (2). Establishing apical patency is...teeth with apical periodontitis that will eventually heal demonstrate signs of healing at 1 year follow-up, and almost 50% are completely healed

  10. Epithelial adhesive junctions

    PubMed Central

    Capaldo, Christopher T.; Farkas, Attila E.

    2014-01-01

    Epithelial adhesive cell-to-cell contacts contain large, plasma membrane-spanning multiprotein aggregates that perform vital structural and signaling functions. Three prominent adhesive contacts are the tight junction, adherens junction, and the desmosome. Each junction type has unique cellular functions and a complex molecular composition. In this review, we comment on recent and exciting advances in our understanding of junction composition and function. PMID:24592313

  11. Wideband rotating junctions

    NASA Astrophysics Data System (ADS)

    Pochernyaev, V. N.

    1993-06-01

    Rotating junctions of coaxial-waveguide and waveguide type with a traveling wave coefficient exceeding 0.8 in a wide frequency range are considered. The design of these junctions is based on a method of the theory of electrodynamic circuits. Numerical results are obtained for rotating junctions of partially filled rectangular waveguide type and their particular cases.

  12. Transforming growth factor-β3 regulates cell junction restructuring via MAPK-mediated mRNA destabilization and Smad-dependent protein degradation of junctional adhesion molecule B (JAM-B).

    PubMed

    Zhang, Xu; Lui, Wing-Yee

    2015-06-01

    Junctional adhesion molecule-B (JAM-B) is found between Sertoli cells at the blood-testis barrier (BTB) as well as between Sertoli and germ cells at the apical ectoplasmic specializations (ES) in the testis. The expression of JAM-B is tightly regulated to modulate the passage of spermatocytes across the BTB as well as the release of mature spermatozoa from the seminiferous epithelium. Transforming growth factor beta (TGF-β) family is implicated in the regulation of testicular cell junction dynamics during spermatogenesis. This study aims to investigate the effects of TGF-β3 on the expression of JAM-B as well as the underlying mechanisms on how TGF-β3 regulates JAM-B expression to facilitate the disassembly of the BTB and apical ES. Our results revealed that TGF-β3 suppresses JAM-B at post-transcriptional and post-translational levels. Inhibitor, siRNA knockdown and co-immunoprecipitation have shown that TGF-β3 induces JAM-B protein degradation via ubiquitin-proteasome pathway. Immunofluorescence staining further confirmed that blockage of ubiquitin-proteasome pathway could abrogate TGF-β3-induced loss of JAM-B at the cell-cell interface. siRNA knockdown and immunofluorescence staining also demonstrated that activation of Smad signaling is required for TGF-β3-induced JAM-B protein degradation. In addition, TGF-β3 reduces JAM-B mRNA levels, at least in part, via post-transcriptional regulation. mRNA stability assay has confirmed that TGF-β3 promotes the degradation of JAM-B transcript and TGF-β3-mediated mRNA destabilization requires the activation of ERK1/2 and p54 JNK signal cascades. Taken together, TGF-β3 significantly downregulates JAM-B expression via post-transcriptional and post-translational modulation and results in the disruption of BTB and apical ES.

  13. Structure and function of gap junction proteins: role of gap junction proteins in embryonic heart development.

    PubMed

    Ahir, Bhavesh K; Pratten, Margaret K

    2014-01-01

    Intercellular (cell-to-cell) communication is a crucial and complex mechanism during embryonic heart development. In the cardiovascular system, the beating of the heart is a dynamic and key regulatory process, which is functionally regulated by the coordinated spread of electrical activity through heart muscle cells. Heart tissues are composed of individual cells, each bearing specialized cell surface membrane structures called gap junctions that permit the intercellular exchange of ions and low molecular weight molecules. Gap junction channels are essential in normal heart function and they assist in the mediated spread of electrical impulses that stimulate synchronized contraction (via an electrical syncytium) of cardiac tissues. This present review describes the current knowledge of gap junction biology. In the first part, we summarise some relevant biochemical and physiological properties of gap junction proteins, including their structure and function. In the second part, we review the current evidence demonstrating the role of gap junction proteins in embryonic development with particular reference to those involved in embryonic heart development. Genetics and transgenic animal studies of gap junction protein function in embryonic heart development are considered and the alteration/disruption of gap junction intercellular communication which may lead to abnormal heart development is also discussed.

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

    PubMed

    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.

  15. Inflammatory Myofibroblastic Tumor Mimicking Apical Periodontitis.

    PubMed

    Adachi, Makoto; Kiho, Kazuki; Sekine, Genta; Ohta, Takahisa; Matsubara, Makoto; Yoshida, Takakazu; Katsumata, Akitoshi; Tanuma, Jun-ichi; Sumitomo, Shinichiro

    2015-12-01

    Inflammatory myofibroblastic tumors (IMTs) are rare. IMTs of the head and neck occur in all age groups, from neonates to old age, with the highest incidence occurring in childhood and early adulthood. An IMT has been defined as a histologically distinctive lesion of uncertain behavior. This article describes an unusual case of IMT mimicking apical periodontitis in the mandible of a 42-year-old man. At first presentation, the patient showed spontaneous pain and percussion pain at teeth #28 to 30, which continued after initial endodontic treatment. Panoramic radiography revealed a radiolucent lesion at the site. Cone-beam computed tomographic imaging showed osteolytic lesions, suggesting an aggressive neoplasm requiring incisional biopsy. Histopathological examination indicated an IMT. The lesion was removed en bloc under general anesthesia, and the patient manifested no clinical evidence of recurrence for 24 months. Lesions of nonendodontic origin should be included in the differential diagnosis of apical periodontitis. Every available diagnostic tool should be used to confirm the diagnosis. Cone-beam computed tomographic imaging is very helpful for differential diagnosis in IMTs mimicking apical periodontitis.

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

    PubMed

    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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26209645

  18. Breast cancer resistance protein regulates apical ectoplasmic specialization dynamics stage specifically in the rat testis.

    PubMed

    Qian, Xiaojing; Mruk, Dolores D; Wong, Elissa W P; Cheng, C Yan

    2013-04-01

    Drug transporters determine the bioavailability of drugs in the testis behind the blood-testis barrier (BTB). Thus, they are crucial for male contraceptive development if these drugs (e.g., adjudin) exert their effects behind the BTB. Herein breast cancer resistance protein (Bcrp), an efflux drug transporter, was found to be expressed by both Sertoli and germ cells. Interestingly, Bcrp was not a component of the Sertoli cell BTB. Instead, it was highly expressed by peritubular myoid cells at the tunica propria and also endothelial cells of the microvessels in the interstitium at all stages of the epithelial cycle. Unexpectedly, Bcrp was found to be expressed at the Sertoli-step 18-19 spermatid interface but limited to stage VI-early VIII tubules, and an integrated component of the apical ectoplasmic specialization (apical ES). Apparently, Bcrp is being used by late-stage spermatids to safeguard their completion of spermiogenesis by preventing harmful drugs to enter these cells while they transform to spermatozoa. Also, the association of Bcrp with actin, Eps8 (epidermal growth factor receptor pathway substrate 8, an actin barbed end capping and bundling protein), and Arp3 (actin-related protein 3, a component of the Arp2/3 complex known to induce branched actin polymerization) at the apical ES suggest that Bcrp may be involved in regulating the organization of actin filament bundles at the site. Indeed, a knockdown of Bcrp by RNAi in the testis perturbed the apical ES function, disrupting spermatid polarity and adhesion. In summary, Bcrp is a regulator of the F-actin-rich apical ES in the testis.

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

    PubMed

    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.

  20. Experimental fluid dynamics of transventricular apical aortic cannulation.

    PubMed

    Fukuda, Ikuo; Yanaoka, Hideki; Inamura, Takao; Minakawa, Masahito; Daitoku, Kazuyuki; Suzuki, Yasuyuki

    2010-03-01

    To clarify the flow pattern from a transventricular apical aortic cannula, hydrodynamic analysis of transventricular apical aortic cannulation (apical cannulation) was performed using particle-image velocimetry in a glass aortic model. Simulated apical cannulation using a 7-mm Sarns Soft-Flow cannula and the newly developed 7-mm apical aortic cannula was compared with standard aortic cannulation. The flow-velocity, streamline, and distribution of magnitude of the strain rate tensor (function of shear stress) were analyzed. Streamline analysis revealed a steady and organized flow profile in apical cannulation as compared with that in standard aortic cannulation. The magnitude of the strain rate tensor decreased within a few centimeters from the exit of the apical cannula.

  1. Endocytosis and Recycling of Tight Junction Proteins in Inflammation

    PubMed Central

    Utech, Markus; Mennigen, Rudolf; Bruewer, Matthias

    2010-01-01

    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. PMID:20011071

  2. Gastrointestinal mucositis: the role of MMP-tight junction interactions in tissue injury.

    PubMed

    Al-Dasooqi, Noor; Wardill, Hannah R; Gibson, Rachel J

    2014-07-01

    Chemotherapy for cancer causes significant gut toxicity known as mucositis. The pathogenesis of mucositis is ill defined. Recent clinical research guidelines have highlighted epithelial junctional complexes as emerging targets within mucositis research. Given the robust biological evidence linking tight junctions and matrix metalloproteinases, key mediators of mucositis, tight junction proteins have received significant attention. Despite this, the link between tight junctions, matrix metalloproteinases and mucositis development is yet to be established. This critical review therefore aims to describe the role of matrix metalloproteinases in mucositis, and how matrix metalloproteinase-dependent tight junction disruption may contribute to the pathobiology of mucositis.

  3. Multiple motifs regulate apical sorting of p75 via a mechanism that involves dimerization and higher-order oligomerization.

    PubMed

    Youker, Robert T; Bruns, Jennifer R; Costa, Simone A; Rbaibi, Youssef; Lanni, Frederick; Kashlan, Ossama B; Teng, Haibing; Weisz, Ora A

    2013-06-01

    The sorting signals that direct proteins to the apical surface of polarized epithelial cells are complex and can include posttranslational modifications, such as N- and O-linked glycosylation. Efficient apical sorting of the neurotrophin receptor p75 is dependent on its O-glycosylated membrane proximal stalk, but how this domain mediates targeting is unknown. Protein oligomerization or clustering has been suggested as a common step in the segregation of all apical proteins. Like many apical proteins, p75 forms dimers, and we hypothesized that formation of higher-order clusters mediated by p75 dimerization and interactions of the stalk facilitate its apical sorting. Using fluorescence fluctuation techniques (photon-counting histogram and number and brightness analyses) to study p75 oligomerization status in vivo, we found that wild-type p75-green fluorescent protein forms clusters in the trans-Golgi network (TGN) but not at the plasma membrane. Disruption of either the dimerization motif or the stalk domain impaired both clustering and polarized delivery. Manipulation of O-glycan processing or depletion of multiple galectins expressed in Madin-Darby canine kidney cells had no effect on p75 sorting, suggesting that the stalk domain functions as a structural prop to position other determinants in the lumenal domain of p75 for oligomerization. Additionally, a p75 mutant with intact dimerization and stalk motifs but with a dominant basolateral sorting determinant (Δ250 mutant) did not form oligomers, consistent with a requirement for clustering in apical sorting. Artificially enhancing dimerization restored clustering to the Δ250 mutant but was insufficient to reroute this mutant to the apical surface. Together these studies demonstrate that clustering in the TGN is required for normal biosynthetic apical sorting of p75 but is not by itself sufficient to reroute a protein to the apical surface in the presence of a strong basolateral sorting determinant. Our studies

  4. Multiple motifs regulate apical sorting of p75 via a mechanism that involves dimerization and higher-order oligomerization

    PubMed Central

    Youker, Robert T.; Bruns, Jennifer R.; Costa, Simone A.; Rbaibi, Youssef; Lanni, Frederick; Kashlan, Ossama B.; Teng, Haibing; Weisz, Ora A.

    2013-01-01

    The sorting signals that direct proteins to the apical surface of polarized epithelial cells are complex and can include posttranslational modifications, such as N- and O-linked glycosylation. Efficient apical sorting of the neurotrophin receptor p75 is dependent on its O-glycosylated membrane proximal stalk, but how this domain mediates targeting is unknown. Protein oligomerization or clustering has been suggested as a common step in the segregation of all apical proteins. Like many apical proteins, p75 forms dimers, and we hypothesized that formation of higher-order clusters mediated by p75 dimerization and interactions of the stalk facilitate its apical sorting. Using fluorescence fluctuation techniques (photon-counting histogram and number and brightness analyses) to study p75 oligomerization status in vivo, we found that wild-type p75–green fluorescent protein forms clusters in the trans-Golgi network (TGN) but not at the plasma membrane. Disruption of either the dimerization motif or the stalk domain impaired both clustering and polarized delivery. Manipulation of O-glycan processing or depletion of multiple galectins expressed in Madin-Darby canine kidney cells had no effect on p75 sorting, suggesting that the stalk domain functions as a structural prop to position other determinants in the lumenal domain of p75 for oligomerization. Additionally, a p75 mutant with intact dimerization and stalk motifs but with a dominant basolateral sorting determinant (Δ250 mutant) did not form oligomers, consistent with a requirement for clustering in apical sorting. Artificially enhancing dimerization restored clustering to the Δ250 mutant but was insufficient to reroute this mutant to the apical surface. Together these studies demonstrate that clustering in the TGN is required for normal biosynthetic apical sorting of p75 but is not by itself sufficient to reroute a protein to the apical surface in the presence of a strong basolateral sorting determinant. Our studies

  5. The effect of irrigation solutions on the apical sealing ability in different root canal sealers.

    PubMed

    Bodrumlu, Emre; Parlak, Esra; Bodrumlu, Ebru Hazar

    2010-01-01

    The aim of this study was to assess the effect of three root canal irrigation solutions on the apical sealing ability of three root canal obturation materials: gutta-percha/AH plus or MM-seal and Resilon/Epiphany SE. A total of 100 teeth with single straight root canals were randomly divided into three equal groups of 30 samples each, with the other 10 teeth (5 positive and 5 negative) used as controls. Each irrigation group was divided into three groups according to the use of three different root canal obturation materials (n = 10): Gutta-percha with AH plus or MM-seal, Resilon with Epiphany SE. The crowns were removed at the cementoenamel junction with a diamond disc under water coolant. The root canals were prepared using step-back technique and irrigation with either sodium hypochlorite (2.5%), chlorhexidine (2%), or MTAD solutions. The roots were obturated with lateral condensation technique using one of the obturation materials. The root surfaces was coated with two layer nail varnish (except apex), placed in 2% methylene blue dye solution, and centrifuged at 3,000 rpm for 5 minutes. Irrigation solutions affected the apical sealing ability of all the sealers. The chlorhexidine irrigation solution exhibited higher apical leakage values than did MTAD and NaOCl in all canal sealers, although the MTAD irrigation solution groups showed the least leakage values. The apical sealing ability of AH plus, Epiphany SE and MM-seal root canal sealers decreased when the chlorhexidine was used as an irrigation solution.

  6. DIFFERENTIATION OF THE JUNCTIONAL COMPLEX OF SURFACE CELLS IN THE DEVELOPING FUNDULUS BLASTODERM

    PubMed Central

    Lentz, Thomas L.; Trinkaus, J. P.

    1971-01-01

    The structure of the junctional complex between surface cells was investigated in blastula, mid gastrula, late gastrula, and early embryo of the teleost fish Fundulus heteroclitus. In blastulae, the intercellular complex is simple and consists of an apical region where the adjacent membranes are closely apposed (40–60 A) and in places touch, an intermediate zone with a wider intercellular space (> 100 A), and incipient desmosomes. In gastrulae, there are frequent points of fusion of membranes along the apical zone of the complex. Dilatations and an increased number of desmosomes in different stages of development are found along the intermediate zone. In mid gastrula, a close or gap junction with an intercellular space of 20 A occurs below the level of the desmosomes. In late gastrula, the gap junction is reduced in extent and desmosomes are better developed. In the early embryo, the basic organization of the complex is the same, although the deeply situated close junctions are no longer apparent and desmosomes and their associated system of filaments are well developed. At this time, the junctional complex is comparable to that of many epithelia and consists of an apical zonula occludens, a short zonula adherens, and deeply situated maculae adherentes. PMID:5545331

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

    PubMed Central

    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 (P<0.001). Conclusions A higher rate of apical microleakage was observed when the final irrigation 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

  8. δ-Aminolevulinate synthase is required for apical transcellular barrier formation in the skin of the Drosophila larva.

    PubMed

    Shaik, Khaleelulla Saheb; Meyer, Frauke; Vázquez, Angel Vizoso; Flötenmeyer, Matthias; Cerdán, Maria Esperanza; Moussian, Bernard

    2012-03-01

    Animals construct a layered skin to prevent dehydration and pathogen entrance. The barrier function of the skin relies on the extensive cross-linking of specialised components. In insects, for instance, epidermal cells produce an apical extracellular cuticle that consists of a network of proteins, chitin and lipids. We have identified mutations in the Drosophila gene coding for the δ-aminolevulinate synthase (Alas) that cause massive water loss. The cuticle of alas mutant larvae detaches from the epidermis and its basal region is frayed suggesting that an Alas dependent pathway is needed to organise the contact between the cuticle and the epidermis and anchor the cuticle to the apical surface of epidermal cells. Concomitantly, reduction of Alas function results in weakening of the extracellular dityrosines network in the cuticle, whereas glutamyl-lysine isopeptide bonds are not affected. The lateral septate junctions of epidermal cells that serve as a paracellular plug are intact, as well. Taken together, we hypothesise that Alas activity, which initiates heme biosynthesis in the mitochondrion, is needed for the formation of a dityrosine-based barrier that confers resistance to the internal hydrostatic pressure protecting both the cuticle from transcellular infiltration of body fluid and the animal from dehydration. We conclude that at least two modules--an apical protein-chitin lattice and the lateral septate junctions, act in parallel to ensure Drosophila skin impermeability.

  9. Internalization of adhesion junction proteins and their association with recycling endosome marker proteins in rat seminiferous epithelium.

    PubMed

    Young, J'Nelle S; Takai, Yoshimi; Kojic, Katarina L; Vogl, A Wayne

    2012-03-01

    Tubulobulbar complexes (TBCs) are elaborate cytoskeleton-related structures that are formed in association with intercellular junctions in the seminiferous epithelium. They consist of a cylindrical double-membrane core composed of the plasma membranes of the two attached cells, cuffed by a dendritic network of actin filaments. TBCs are proposed to be subcellular machines that internalize intercellular junctions during the extensive junction remodeling that occurs during spermatogenesis. At the apical sites of attachment between Sertoli cells and spermatids, junction disassembly is part of the sperm release mechanism. In this study, we used immunological probes to explore junction internalization and recycling at apical TBCs in the rat seminiferous epithelium. We demonstrate that β1-integrin and nectin 2 were concentrated at the ends of TBCs and for the first time show that the early endosome marker RAB5A was also distinctly localized at the ends of TBCs that appear to be the 'bulbar' regions of the complexes. Significantly, we also demonstrate that the 'long-loop' recycling endosome marker RAB11A was co-distributed with nectin 2 at junctions with early spermatids deeper in the epithelium. Our results are consistent with the hypothesis that TBCs associated with late spermatids internalize adhesion junctions and also indicate that some of the internalized junction proteins may be recycled to form junctions with the next generation of spermatids.

  10. Unevenness of the apical constriction in human maxillary central incisors.

    PubMed

    Olson, David G; Roberts, Steven; Joyce, Anthony P; Collins, D Edward; McPherson, James C

    2008-02-01

    This study examined the incisoapical extent of the apical constriction in 45 human maxillary central incisors. The null hypothesis was that the apical constriction is a flat ring. Our working hypothesis was that the constriction is actually uneven or "skewed" as it traces a path around the circumference of the canal. Teeth were split and imaged with 25x magnification, and the most apical and coronal limits of the apical constriction were identified and measured. Analysis of the data indicates that a majority (>70%) of maxillary central incisors exhibit an unevenness or "skew" of the apical constriction of greater than 100 microm in the incisoapical dimension, with a maximum measured skew of 385 microm. On the basis of the results of this study, a statistically significant (P < .05) variation in the longitudinal position of the apical constriction around its circumference was confirmed in maxillary central incisors.

  11. Ontogeny of the maize shoot apical meristem.

    PubMed

    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

    2012-08-01

    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.

  12. MicroRNAs regulate tight junction proteins and modulate epithelial/endothelial barrier functions.

    PubMed

    Cichon, Christoph; Sabharwal, Harshana; Rüter, Christian; Schmidt, M Alexander

    2014-01-01

    Tightly controlled epithelial and endothelial barriers are a prerequisite for life as these barriers separate multicellular organisms from their environment and serve as first lines of defense. Barriers between neighboring epithelial cells are formed by multiple intercellular junctions including the 'apical junctional complex-AJC' with tight junctions (TJ), adherens junctions (AJ), and desmosomes. TJ consist of tetraspan transmembrane proteins like occludin, various claudins that directly control paracellular permeability, and the 'Junctional Adhesion Molecules' (JAMs). For establishing tight barriers TJ are essential but at the same time have to allow also selective permeability. For this, TJ need to be tightly regulated and controlled. This is organized by a variety of adaptor molecules, i.e., protein kinases, phosphatases and GTPases, which in turn are regulated and fine-tuned involving microRNAs (miRNAs). In this review we summarize available data on the role and targeting of miRNAs in the maintenance of epithelial and/or endothelial barriers.

  13. Plectin is a novel regulator for apical extrusion of RasV12-transformed cells

    PubMed Central

    Kadeer, Ailijiang; Maruyama, Takeshi; Kajita, Mihoko; Morita, Tomoko; Sasaki, Ayana; Ohoka, Atsuko; Ishikawa, Susumu; Ikegawa, Masaya; Shimada, Takashi; Fujita, Yasuyuki

    2017-01-01

    Several lines of evidence have revealed that newly emerging transformed cells are often eliminated from the epithelium, though the underlying molecular mechanisms of this cancer preventive phenomenon still remain elusive. In this study, using mammalian cell culture systems we have identified plectin, a versatile cytoskeletal linker protein, as a novel regulator for apical extrusion of RasV12-transformed cells. Plectin is accumulated in RasV12 cells when they are surrounded by normal epithelial cells. Similarly, cytoskeletal proteins tubulin, keratin, and Epithelial Protein Lost In Neoplasm (EPLIN) are also accumulated in the transformed cells surrounded by normal cells. Knockdown or functional disruption of one of these molecules diminishes the accumulation of the others, indicating that the accumulation process of the individual protein mutually depends on each other. Furthermore, plectin-knockdown attenuates caveolin-1 (Cav-1) enrichment and PKA activity in RasV12 cells and profoundly suppresses the apical extrusion. These results indicate that the plectin-microtubules-EPLIN complex positively regulates apical elimination of RasV12-transformed cells from the epithelium in a coordinated fashion. Further development of this study would open a new avenue for cancer preventive medicine. PMID:28281696

  14. The adherens junction is lost during normal pregnancy but not during ovarian hyperstimulated pregnancy.

    PubMed

    Dowland, Samson N; Madawala, Romanthi J; Lindsay, Laura A; Murphy, Christopher R

    2016-03-01

    During early pregnancy in the rat, the luminal uterine epithelial cells (UECs) must transform to a receptive state to permit blastocyst attachment and implantation. The implantation process involves penetration of the epithelial barrier, so it is expected that the transformation of UECs includes alterations in the lateral junctional complex. Previous studies have demonstrated a deepening of the tight junction (zonula occludens) and a reduction in the number of desmosomes (macula adherens) in UECs at the time of implantation. However, the adherens junction (zonula adherens), which is primarily responsible for cell-cell adhesion, has been little studied during early pregnancy. This study investigated the adherens junction in rat UECs during the early stages of normal pregnancy and ovarian hyperstimulated (OH) pregnancy using transmission electron microscopy. The adherens junction is present in UECs at the time of fertilisation, but is lost at the time of blastocyst implantation during normal pregnancy. Interestingly, at the time of implantation after OH, adherens junctions are retained and may impede blastocyst penetration of the epithelium. The adherens junction anchors the actin-based terminal web, which is known to be disrupted in UECs during early pregnancy. However, artificial disruption of the terminal web, using cytochalasin D, did not cause removal of the adherens junction in UECs. This study revealed that adherens junction disassembly occurs during early pregnancy, but that this process does not occur during OH pregnancy. Such disassembly does not appear to depend on the disruption of the terminal web.

  15. Indian Ocean Triple Junction

    SciTech Connect

    Tapscott, C.R.; Patriat, P.; Fisher, R.L.; Sclater, J.G.; Hoskins, H.; Parsons, B.

    1980-09-10

    The boundaries of three major plates (Africa, India, and Antarctica) meet in a triple junction in the Indian Ocean near 25 /sup 0/S, 70 /sup 0/E. Using observed bathymetry and magnetic anomalies, we locate the junction to within 5 km and show that it is a ridge-ridge-ridge type. Relative plate motion is N60 /sup 0/E at 50 mm/yr (full rate) across the Central Indian Ridge, N47 /sup 0/E at 60 mm/yr across the Southeast Indian Ridge, and N3 /sup 0/W at 15 mm/yr across te Southwest Indian Ridge; the observed velocity triangle is closed. Poles of instantaneous relative plate motion are determined for all plate pairs. The data in the South Atlantic and Indian oceans are consistent with a rigid African plate without significant internal deformation. Two of the ridges at the triple junction are normal midocean spreading centers with well-defined median valleys. The Southwest Indian Ridge, however, has a peculiar morphology near the triple junction, that of an elongate triangular deep, with the triple junction at its apex. The floor of the deep represents crust formed at the Southwest Indian Ridge, and the morphology is a consequence of the evolution of the triple junction and is similar to that at the Galapagos Triple Junction. Though one cannot determine with precision the stability conditions at the triple junction, the development of the junction over the last 10 m.y. can be mapped, and the topographic expressions of the triple junction traces may be detected on the three plates.

  16. Apical phosphatidylserine externalization in auditory hair cells.

    PubMed

    Shi, Xiaorui; Gillespie, Peter G; Nuttall, Alfred L

    2007-01-01

    In hair cells of the inner ear, phosphatidylserine (PS), detected with fluorescent annexin V labeling, was rapidly exposed on the external leaflet of apical plasma membranes upon dissection of the organ of Corti. PS externalization was unchanged by caspase inhibition, suggesting that externalization did not portend apoptosis or necrosis. Consistent with that conclusion, mitochondrial membrane potential and hair-cell nuclear structure remained normal during externalization. PS externalization was triggered by forskolin, which raises cAMP, and blocked by inhibitors of adenylyl cyclase. Blocking Na(+) influx by inhibiting the mechanoelectrical transduction channels and P2X ATP channels also inhibited external PS externalization. Diminished PS externalization was also seen in cells exposed to LY 294002, which blocks membrane recycling in hair cells by inhibiting phosphatidylinositol 3-kinase. These results indicate that PS exposure on the external leaflet, presumably requiring vesicular transport, results from elevation of intracellular cAMP, which can be triggered by Na(+) entry into hair cells.

  17. AB223. Expression of tight junction proteins in rat vagina

    PubMed Central

    Oh, Kyung Jin; Lee, Hyun-Suk; Chung, Ho Suck; Ahn, Kyu Youn; Park, Kwangsung

    2014-01-01

    Aim Tight junction plays a role in apical cell-to-cell adhesion and epithelial polarity. In this study, we investigated the expression of tight junction proteins, such as Claudin-1, zonula occludens (ZO)-1, junction adhesion molecule (JAM)-A, and occludin in rat vagina. Methods Female Sprague-dawley rats (230-240 g, n=20) were divided into two groups: control (n=10) and bilateral ovariectomy (n=10). The expression and cellular localization of claudin-1, ZO-1, JAM-A, and occludin were determined in each group by immunohistochemistry and Western blot. Results Immunolabeling of ZO-1 was mainly expressed in the capillaries and venules of the vagina. Claudin-1, JAM-A, and occludin were expressed in the epithelium of the vagina. The immunoreactivity and protein expression of claudin-1 was significantly decreased in the ovariectomy group compared with the control group. Conclusions Our results suggest that tight junction proteins may have an important role in the vagina. Further studies are needed to clarify the role of each tight junction protein on vaginal lubrication.

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

    PubMed Central

    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 < 0.05). The apical sealing ability of Biodentine was comparable to MTA at any apical plug thickness. PMID:26436090

  19. Rab14 specifies the apical membrane through Arf6-mediated regulation of lipid domains and Cdc42

    PubMed Central

    Lu, Ruifeng; Wilson, Jean M.

    2016-01-01

    The generation of cell polarity is essential for the development of multi-cellular organisms as well as for the function of epithelial organs in the mature animal. Small GTPases regulate the establishment and maintenance of polarity through effects on cytoskeleton, membrane trafficking, and signaling. Using short-term 3-dimensional culture of MDCK cells, we find that the small GTPase Rab14 is required for apical membrane specification. Rab14 knockdown results in disruption of polarized lipid domains and failure of the Par/aPKC/Cdc42 polarity complex to localize to the apical membrane. These effects are mediated through tight control of lipid localization, as overexpression of the phosphatidylinositol 4-phosphate 5-kinase α [PtdIns(4)P5K] activator Arf6 or PtdIns(4)P5K alone, or treatment with the phosphatidylinositol 3-kinase (PtdInsI3K) inhibitor wortmannin, rescued the multiple-apical domain phenotype observed after Rab14 knockdown. Rab14 also co-immunoprecipitates and colocalizes with the small GTPase Cdc42, and Rab14 knockdown results in increased Cdc42 activity. Furthermore, Rab14 regulates trafficking of vesicles to the apical domain, mitotic spindle orientation, and midbody position, consistent with Rab14’s reported localization to the midbody as well as its effects upon Cdc42. These results position Rab14 at the top of a molecular cascade that regulates the establishment of cell polarity. PMID:27901125

  20. Antidromic-rectifying gap junctions amplify chemical transmission at functionally mixed electrical-chemical synapses.

    PubMed

    Liu, Ping; Chen, Bojun; Mailler, Roger; Wang, Zhao-Wen

    2017-03-20

    Neurons communicate through chemical synapses and electrical synapses (gap junctions). Although these two types of synapses often coexist between neurons, little is known about whether they interact, and whether any interactions between them are important to controlling synaptic strength and circuit functions. By studying chemical and electrical synapses between premotor interneurons (AVA) and downstream motor neurons (A-MNs) in the Caenorhabditis elegans escape circuit, we found that disrupting either the chemical or electrical synapses causes defective escape response. Gap junctions between AVA and A-MNs only allow antidromic current, but, curiously, disrupting them inhibits chemical transmission. In contrast, disrupting chemical synapses has no effect on the electrical coupling. These results demonstrate that gap junctions may serve as an amplifier of chemical transmission between neurons with both electrical and chemical synapses. The use of antidromic-rectifying gap junctions to amplify chemical transmission is potentially a conserved mechanism in circuit functions.

  1. Antidromic-rectifying gap junctions amplify chemical transmission at functionally mixed electrical-chemical synapses

    PubMed Central

    Liu, Ping; Chen, Bojun; Mailler, Roger; Wang, Zhao-Wen

    2017-01-01

    Neurons communicate through chemical synapses and electrical synapses (gap junctions). Although these two types of synapses often coexist between neurons, little is known about whether they interact, and whether any interactions between them are important to controlling synaptic strength and circuit functions. By studying chemical and electrical synapses between premotor interneurons (AVA) and downstream motor neurons (A-MNs) in the Caenorhabditis elegans escape circuit, we found that disrupting either the chemical or electrical synapses causes defective escape response. Gap junctions between AVA and A-MNs only allow antidromic current, but, curiously, disrupting them inhibits chemical transmission. In contrast, disrupting chemical synapses has no effect on the electrical coupling. These results demonstrate that gap junctions may serve as an amplifier of chemical transmission between neurons with both electrical and chemical synapses. The use of antidromic-rectifying gap junctions to amplify chemical transmission is potentially a conserved mechanism in circuit functions. PMID:28317880

  2. Quantum junction solar cells.

    PubMed

    Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H

    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.

  3. Evaluation of Correlation Between apical Diameter and File Size Using Propex Pixi Apex Locator

    PubMed Central

    Bolla, Nagesh; Varri, Sujana; Thummu, Jayaprakash; Vemuri, Sayesh; Mandava, Pragna

    2014-01-01

    Aim: Aim of this study is to evaluate the influence of critical diameter of apical foramen and file size using propex pixi apex locator in working length determination. Materials and Methods: In this study, ten single rooted teeth were selected. They were decoronated at cemento enamel junction. After determining the actual working length, they were embedded in alginate mold. Foramina were widened from 0.6mm to 0.8mm. The measurements were taken with electronic apex locator propex pixi with files from sizes 10 K to respective sizes. Statistical accuracy of propex pixi was calculated by using Anova test for different diameters and for the influence of file size. Results: Results showed that propex pixi apex locator was accurate when foramen diameter is 0.6 (60k file size), its accuracy diminished with increased foramen diameter Conclusion: Propex pixi is accurate for foramen diameter of 0.6mm, independent of file size. Its accuracy decreases as apical foramen widens, so care should be taken when using clinically. PMID:25654023

  4. A histone octamer blocks branch migration of a Holliday junction.

    PubMed Central

    Grigoriev, M; Hsieh, P

    1997-01-01

    The Holliday junction is a key intermediate in genetic recombination. Here, we examine the effect of a nucleosome core on movement of the Holliday junction in vitro by spontaneous branch migration. Histone octamers consisting of H2A, H2B, H3, and H4 are reconstituted onto DNA duplexes containing an artificial nucleosome-positioning sequence consisting of a tandem array of an alternating AT-GC sequence motif. Characterization of the reconstituted branch migration substrates by micrococcal nuclease mapping and exonuclease III and hydroxyl radical footprinting reveal that 70% of the reconstituted octamers are positioned near the center of the substrate and the remaining 30% are located at the distal end, although in both cases some translational degeneracy is observed. Branch migration assays with the octamer-containing substrates reveal that the Holliday junction cannot migrate spontaneously through DNA organized into a nucleosomal core unless DNA-histone interactions are completely disrupted. Similar results are obtained with branch migration substrates containing an octamer positioned on a naturally occurring sequence derived from the yeast GLN3 locus. Digestion of Holliday junctions with T7 endonuclease I establishes that the junction is not trapped by the octamer but can branch migrate in regions free of histone octamers. Our findings suggest that migration of Holliday junctions during recombination and the recombinational repair of DNA damage requires proteins not only to accelerate the intrinsic rate of branch migration but also to facilitate the passage of the Holliday junction through a nucleosome. PMID:9372946

  5. Apical surgery: A review of current techniques and outcome

    PubMed Central

    von Arx, Thomas

    2010-01-01

    Apical surgery is considered a standard oral surgical procedure. It is often a last resort to surgically maintain a tooth with a periapical lesion that cannot be managed with conventional endodontic (re-)treatment. The main goal of apical surgery is to prevent bacterial leakage from the root-canal system into the periradicular tissues by placing a tight root-end filling following root-end resection. Clinicians are advised to utilize a surgical microscope to perform apical surgery to benefit from magnification and illumination. In addition, the application of microsurgical techniques in apical surgery, i.e., gentle incision and flap elevation, production of a small osteotomy, and the use of sonic- or ultrasonic driven microtips, will result in less trauma to the patient and faster postsurgical healing. A major step in apical surgery is to identify possible leakage areas at the cut root face and subsequently to ensure adequate root-end filling. Only a tight and persistent apical obturation will allow periapical healing with good long-term prognosis. The present paper describes current indications, techniques and outcome of apical surgery. PMID:24151412

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

    PubMed Central

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

    2013-01-01

    Takotsubo cardiomyopathy, which is also known as "transient apical ballooning", is a cardiac syndrome associated with emotional and physical stress that occurs in postmenopausal women. It may mimic acute coronary syndrome but coronary angiography reveals normal epicardial coronary arteries. 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. Takotsubo cardiomyopathy may not be always transient and left ventricular thrombus can occur in the disease course as our patient. PMID:24198920

  7. Four-junction superconducting circuit

    NASA Astrophysics Data System (ADS)

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

    2016-06-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit.

  8. Evaluation of Apical Microleakage in Open Apex Teeth Using MTA Apical Plug in Different Sessions

    PubMed Central

    Yazdizadeh, Mohammad; Bouzarjomehri, Zeinab; Khalighinejad, Navid; Sadri, Leyli

    2013-01-01

    Aim. To compare microleakage of apexification using MTA in one or two sessions. Materials and Methods. 88 single rooted teeth were prepared and divided into two groups then received MTA apical plug. In the first group, the teeth were immersed in normal saline for 24 hours and then backfilled with guttapercha and AH26 sealer. In the second group, the teeth were obturated immediately after receiving apical plug. Four positive and four negative controls were selected. All specimens were placed in 1% methylene blue and decalcified in 5% nitric acid and finally were placed in methyl salicylate until getting transparent. All teeth were visualized for assessment of dye penetration under stereo dissecting microscope. Results. 36 and 35 teeth showed dye leakage in the first and second groups. Dye penetration into the entire canal length was confirmed in the positive control group, and in the negative control group no dye penetration was seen. Mean dye penetration in the first and second group was 5813 and 9152 μm. t-test revealed a significant difference between dye penetrations of two groups (P < 0.05). Conclusion. MTA requires adequate time for setting in the presence of the moisture, and final obturation should be delayed until final setting of MTA. PMID:24282642

  9. Dot junction solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Crotty, G. T.

    1986-01-01

    A design of solar cells with reduced junction area on the cell surface is investigated for reduction of saturation current and increase in open-circuit voltage. Equidiameter dot junctions distributed across the surface of the cell offer an efficient alternative, with variations in dot diameter and in the spacing between dots giving the required variations in the ratio of junction area to total surface area. A simplified analysis for short-circuit current and other cell parameters, which enables cell design optimization, is presented. Experimental solar-cell performance results, as functions of different area ratios, are presented and compared with the model. It is shown that saturation current reduction is possible for achieving efficiencies as high as 18 percent in flat-plate terrestrial applications.

  10. Haemostatic agents in apical surgery. A systematic review

    PubMed Central

    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

  11. Visualization of removal of trapped air from the apical region in simulated root canals by laser-activated irrigation using an Er,Cr:YSGG laser.

    PubMed

    Peeters, Harry Huiz; De Moor, Roeland J G; Suharto, Djoko

    2015-08-01

    The aim of this visualization study was to obtain a better understanding of the mechanism by which trapped air is removed from the apical region of simulated root canals by activation of an irrigant using an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser during endodontic procedures. A high-speed imaging system with high temporal and spatial resolution was used to visualize laser-induced shock waves in a resin block model with a curved root canal (inner diameter at the apex 0.08 mm, taper 4 %, crown height 10 mm, overall length 40 mm) and a glass cylinder model with a straight root canal (inner diameter 1 mm, crown height 10 mm, overall length 40 mm). The study utilized MZ3 and RFT3 tips in each model, without water or air spray, and with an average power of 1 W at 35 Hz. Laser-activated irrigation overcame the airlock effect by releasing air trapped in the air column. The mechanism underlying the removal of trapped air from the apical region using an Er,Cr:YSGG laser in a dry root canal is via the disruption of the surface tension at the solution-air interface. This disruption, caused by bubble implosion (cavitation), displaces air in the form of bubbles from the apical region toward the solution, which allows the solution to travel apically.

  12. Healing of apical rarefaction of three nonvital open apex anterior teeth using a white portland cement apical plug

    PubMed Central

    Chakraborty, Amitabha; Dey, Bibhas; Dhar, Reema; Sardar, Prabir

    2012-01-01

    The major challenge of performing root canal treatment in an open apex pulp-less tooth is to obtain a good apical seal. MTA has been successfully used to achieve a good apical seal, wherein the root canal obturation can be done immediately. MTA and White Portland Cement has been shown similarity in their physical, chemical and biological properties and has also shown similar outcome when used in animal studies and human trials. In our study, open apex of three non vital upper central incisors has been plugged using modified white Portland cement. 3 to 6 months follow up revealed absence of clinical symptoms and disappearance of peri-apical rarefactions. The positive clinical outcome may encourage the future use of white Portland cement as an apical plug material in case of non vital open apex tooth as much cheaper substitute of MTA. PMID:23230357

  13. Healing of apical rarefaction of three nonvital open apex anterior teeth using a white portland cement apical plug.

    PubMed

    Chakraborty, Amitabha; Dey, Bibhas; Dhar, Reema; Sardar, Prabir

    2012-09-01

    The major challenge of performing root canal treatment in an open apex pulp-less tooth is to obtain a good apical seal. MTA has been successfully used to achieve a good apical seal, wherein the root canal obturation can be done immediately. MTA and White Portland Cement has been shown similarity in their physical, chemical and biological properties and has also shown similar outcome when used in animal studies and human trials. In our study, open apex of three non vital upper central incisors has been plugged using modified white Portland cement. 3 to 6 months follow up revealed absence of clinical symptoms and disappearance of peri-apical rarefactions. The positive clinical outcome may encourage the future use of white Portland cement as an apical plug material in case of non vital open apex tooth as much cheaper substitute of MTA.

  14. Multiciliated cell basal bodies align in stereotypical patterns coordinated by the apical cytoskeleton

    PubMed Central

    Herawati, Elisa; Kanoh, Hatsuho

    2016-01-01

    Multiciliated cells (MCCs) promote fluid flow through coordinated ciliary beating, which requires properly organized basal bodies (BBs). Airway MCCs have large numbers of BBs, which are uniformly oriented and, as we show here, align linearly. The mechanism for BB alignment is unexplored. To study this mechanism, we developed a long-term and high-resolution live-imaging system and used it to observe green fluorescent protein–centrin2–labeled BBs in cultured mouse tracheal MCCs. During MCC differentiation, the BB array adopted four stereotypical patterns, from a clustering “floret” pattern to the linear “alignment.” This alignment process was correlated with BB orientations, revealed by double immunostaining for BBs and their asymmetrically associated basal feet (BF). The BB alignment was disrupted by disturbing apical microtubules with nocodazole and by a BF-depleting Odf2 mutation. We constructed a theoretical model, which indicated that the apical cytoskeleton, acting like a viscoelastic fluid, provides a self-organizing mechanism in tracheal MCCs to align BBs linearly for mucociliary transport. PMID:27573463

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

    PubMed Central

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

    2016-01-01

    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. PMID:27402760

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

    PubMed Central

    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

    PubMed Central

    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. Victory Junction Gang Camp

    ERIC Educational Resources Information Center

    Shell, Ryan

    2007-01-01

    This article describes the Victory Junction Gang Camp, a not-for-profit, NASCAR-themed camp for children with chronic medical conditions that serves 24 different disease groups. The mission of the camp is to give children life-changing camping experiences that are exciting, fun, and empowering in a safe and medically sound environment. While doing…

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

    PubMed Central

    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

  20. Babesia divergens and Neospora caninum apical membrane antigen 1 structures reveal selectivity and plasticity in apicomplexan parasite host cell invasion

    PubMed Central

    Tonkin, Michelle L; Crawford, Joanna; Lebrun, Maryse L; Boulanger, Martin J

    2013-01-01

    Host cell invasion by the obligate intracellular apicomplexan parasites, including Plasmodium (malaria) and Toxoplasma (toxoplasmosis), requires a step-wise mechanism unique among known host–pathogen interactions. A key step is the formation of the moving junction (MJ) complex, a circumferential constriction between the apical tip of the parasite and the host cell membrane that traverses in a posterior direction to enclose the parasite in a protective vacuole essential for intracellular survival. The leading model of MJ assembly proposes that Rhoptry Neck Protein 2 (RON2) is secreted into the host cell and integrated into the membrane where it serves as the receptor for apical membrane antigen 1 (AMA1) on the parasite surface. We have previously demonstrated that the AMA1-RON2 interaction is an effective target for inhibiting apicomplexan invasion. To better understand the AMA1-dependant molecular recognition events that promote invasion, including the significant AMA1-RON2 interaction, we present the structural characterization of AMA1 from the apicomplexan parasites Babesia divergens (BdAMA1) and Neospora caninum (NcAMA1) by X-ray crystallography. These studies offer intriguing structural insight into the RON2-binding surface groove in the AMA1 apical domain, which shows clear evidence for receptor–ligand co-evolution, and the hyper variability of the membrane proximal domain, which in Plasmodium is responsible for direct binding to erythrocytes. By incorporating the structural analysis of BdAMA1 and NcAMA1 with existing AMA1 structures and complexes we were able to define conserved pockets in the AMA1 apical groove that could be targeted for the design of broadly reactive therapeutics. PMID:23169033

  1. Intercellular junctions in myriapods.

    PubMed

    Dallai, R; Bigliardi, E; Lane, N J

    1990-01-01

    Tissue from the intestinal tract of myriapods, including millipedes, centipedes and pauropods were examined in tracer-impregnated sections and freeze-fracture replicas. The foregut and hindgut of all three classes exhibit pleated septate junctions; these display undulating intercellular ribbons in thin sections. In replicas they show discrete intramembranous particle (IMP) arrays aligned in rows in parallel; with one another. The tissues of the hindgut also possess scalariform junctions, characterized by cross-striated intercellular clefts in sections and IMP-enriched membranes in replicas. Gap junctions occur in all groups, but they are atypical in replicas in that their component IMPs do not always fracture onto the E face, as is characteristic of other arthropods; some IMPs cleave to the P face and others to the E face. The midgut of these organisms exhibits smooth septate junctions with conventional straight septal ribbons and occasional interseptal columns. However the intramembranous appearance in replicas is variable, particularly in centipedes, in that the rows of IMPs in chemically-unfixed propanecryofixed tissues, are prominent and adhere preferentially to the E face, with complementary P face grooves, while in fixed tissues the IMPs are much less distinct and fracture to either P face or E face. They tend not to protrude far beyond the mid-plane of the membrane bilayer and lie in rows which commonly take on the form of a network. Individual rows of the network sometimes curve to run beside a second row, over a short distance, before bending away into another part of the network. The aligned particle rows, which are much more prominent in millipedes, where they frequently lie in close parallel appositions, do not fuse into ridges as often occurs in insect tissues. The myriapod junctions, therefore, are of the same general kind as are found in the gut tract of other arthropod groups, but differ with respect to the subtleties of their intramembranous

  2. GLUT2 Accumulation in Enterocyte Apical and Intracellular Membranes

    PubMed Central

    Ait-Omar, Amal; Monteiro-Sepulveda, Milena; Poitou, Christine; Le Gall, Maude; Cotillard, Aurélie; Gilet, Jules; Garbin, Kevin; Houllier, Anne; Château, Danièle; Lacombe, Amélie; Veyrie, Nicolas; Hugol, Danielle; Tordjman, Joan; Magnan, Christophe; Serradas, Patricia; Clément, Karine; Leturque, Armelle; Brot-Laroche, Edith

    2011-01-01

    OBJECTIVE In healthy rodents, intestinal sugar absorption in response to sugar-rich meals and insulin is regulated by GLUT2 in enterocyte plasma membranes. Loss of insulin action maintains apical GLUT2 location. In human enterocytes, apical GLUT2 location has not been reported but may be revealed under conditions of insulin resistance. RESEARCH DESIGN AND METHODS Subcellular location of GLUT2 in jejunal enterocytes was analyzed by confocal and electron microscopy imaging and Western blot in 62 well-phenotyped morbidly obese subjects and 7 lean human subjects. GLUT2 locations were assayed in ob/ob and ob/+ mice receiving oral metformin or in high-fat low-carbohydrate diet–fed C57Bl/6 mice. Glucose absorption and secretion were respectively estimated by oral glucose tolerance test and secretion of [U-14C]-3-O-methyl glucose into lumen. RESULTS In human enterocytes, GLUT2 was consistently located in basolateral membranes. Apical GLUT2 location was absent in lean subjects but was observed in 76% of obese subjects and correlated with insulin resistance and glycemia. In addition, intracellular accumulation of GLUT2 with early endosome antigen 1 (EEA1) was associated with reduced MGAT4a activity (glycosylation) in 39% of obese subjects on a low-carbohydrate/high-fat diet. Mice on a low-carbohydrate/high-fat diet for 12 months also exhibited endosomal GLUT2 accumulation and reduced glucose absorption. In ob/ob mice, metformin promoted apical GLUT2 and improved glucose homeostasis. Apical GLUT2 in fasting hyperglycemic ob/ob mice tripled glucose release into intestinal lumen. CONCLUSIONS In morbidly obese insulin-resistant subjects, GLUT2 was accumulated in apical and/or endosomal membranes of enterocytes. Functionally, apical GLUT2 favored and endosomal GLUT2 reduced glucose transepithelial exchanges. Thus, altered GLUT2 locations in enterocytes are a sign of intestinal adaptations to human metabolic pathology. PMID:21852673

  3. ZO-1 controls endothelial adherens junctions, cell-cell tension, angiogenesis, and barrier formation.

    PubMed

    Tornavaca, Olga; Chia, Minghao; Dufton, Neil; Almagro, Lourdes Osuna; Conway, Daniel E; Randi, Anna M; Schwartz, Martin A; Matter, Karl; Balda, Maria S

    2015-03-16

    Intercellular junctions are crucial for mechanotransduction, but whether tight junctions contribute to the regulation of cell-cell tension and adherens junctions is unknown. Here, we demonstrate that the tight junction protein ZO-1 regulates tension acting on VE-cadherin-based adherens junctions, cell migration, and barrier formation of primary endothelial cells, as well as angiogenesis in vitro and in vivo. ZO-1 depletion led to tight junction disruption, redistribution of active myosin II from junctions to stress fibers, reduced tension on VE-cadherin and loss of junctional mechanotransducers such as vinculin and PAK2, and induced vinculin dissociation from the α-catenin-VE-cadherin complex. Claudin-5 depletion only mimicked ZO-1 effects on barrier formation, whereas the effects on mechanotransducers were rescued by inhibition of ROCK and phenocopied by JAM-A, JACOP, or p114RhoGEF down-regulation. ZO-1 was required for junctional recruitment of JACOP, which, in turn, recruited p114RhoGEF. ZO-1 is thus a central regulator of VE-cadherin-dependent endothelial junctions that orchestrates the spatial actomyosin organization, tuning cell-cell tension, migration, angiogenesis, and barrier formation.

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

    PubMed Central

    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

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

    PubMed

    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.

  6. Asymmetric inheritance of the apical domain and self-renewal of retinal ganglion cell progenitors depend on Anillin function.

    PubMed

    Paolini, Alessio; Duchemin, Anne-Laure; Albadri, Shahad; Patzel, Eva; Bornhorst, Dorothee; González Avalos, Paula; Lemke, Steffen; Machate, Anja; Brand, Michael; Sel, Saadettin; Di Donato, Vincenzo; Del Bene, Filippo; Zolessi, Flavio R; Ramialison, Mirana; Poggi, Lucia

    2015-03-01

    Divisions that generate one neuronal lineage-committed and one self-renewing cell maintain the balance of proliferation and differentiation for the generation of neuronal diversity. The asymmetric inheritance of apical domains and components of the cell division machinery has been implicated in this process, and might involve interactions with cell fate determinants in regulatory feedback loops of an as yet unknown nature. Here, we report the dynamics of Anillin - an essential F-actin regulator and furrow component - and its contribution to progenitor cell divisions in the developing zebrafish retina. We find that asymmetrically dividing retinal ganglion cell progenitors position the Anillin-rich midbody at the apical domain of the differentiating daughter. anillin hypomorphic conditions disrupt asymmetric apical domain inheritance and affect daughter cell fate. Consequently, the retinal cell type composition is profoundly affected, such that the ganglion cell layer is dramatically expanded. This study provides the first in vivo evidence for the requirement of Anillin during asymmetric neurogenic divisions. It also provides insights into a reciprocal regulation between Anillin and the ganglion cell fate determinant Ath5, suggesting a mechanism whereby the balance of proliferation and differentiation is accomplished during progenitor cell divisions in vivo.

  7. Apical oscillations in amnioserosa cells: basolateral coupling and mechanical autonomy.

    PubMed

    Jayasinghe, Aroshan K; Crews, Sarah M; Mashburn, David N; Hutson, M Shane

    2013-07-02

    Holographic laser microsurgery is used to isolate single amnioserosa cells in vivo during early dorsal closure. During this stage of Drosophila embryogenesis, amnioserosa cells undergo oscillations in apical surface area. The postisolation behavior of individual cells depends on their preisolation phase in these contraction/expansion cycles: cells that were contracting tend to collapse quickly after isolation; cells that were expanding do not immediately collapse, but instead pause or even continue to expand for ∼40 s. In either case, the postisolation apical collapse can be prevented by prior anesthetization of the embryos with CO2. These results suggest that although the amnioserosa is under tension, its cells are subjected to only small elastic strains. Furthermore, their postisolation apical collapse is not a passive elastic relaxation, and both the contraction and expansion phases of their oscillations are driven by intracellular forces. All of the above require significant changes to existing computational models.

  8. Apical Oscillations in Amnioserosa Cells: Basolateral Coupling and Mechanical Autonomy

    PubMed Central

    Jayasinghe, Aroshan K.; Crews, Sarah M.; Mashburn, David N.; Hutson, M. Shane

    2013-01-01

    Holographic laser microsurgery is used to isolate single amnioserosa cells in vivo during early dorsal closure. During this stage of Drosophila embryogenesis, amnioserosa cells undergo oscillations in apical surface area. The postisolation behavior of individual cells depends on their preisolation phase in these contraction/expansion cycles: cells that were contracting tend to collapse quickly after isolation; cells that were expanding do not immediately collapse, but instead pause or even continue to expand for ∼40 s. In either case, the postisolation apical collapse can be prevented by prior anesthetization of the embryos with CO2. These results suggest that although the amnioserosa is under tension, its cells are subjected to only small elastic strains. Furthermore, their postisolation apical collapse is not a passive elastic relaxation, and both the contraction and expansion phases of their oscillations are driven by intracellular forces. All of the above require significant changes to existing computational models. PMID:23823245

  9. Fractional order junctions

    NASA Astrophysics Data System (ADS)

    Machado, J. Tenreiro

    2015-01-01

    Gottfried Leibniz generalized the derivation and integration, extending the operators from integer up to real, or even complex, orders. It is presently recognized that the resulting models capture long term memory effects difficult to describe by classical tools. Leon Chua generalized the set of lumped electrical elements that provide the building blocks in mathematical models. His proposal of the memristor and of higher order elements broadened the scope of variables and relationships embedded in the development of models. This paper follows the two directions and proposes a new logical step, by generalizing the concept of junction. Classical junctions interconnect system elements using simple algebraic restrictions. Nevertheless, this simplistic approach may be misleading in the presence of unexpected dynamical phenomena and requires including additional "parasitic" elements. The novel γ -junction includes, as special cases, the standard series and parallel connections and allows a new degree of freedom when building models. The proposal motivates the search for experimental and real world manifestations of the abstract conjectures.

  10. Thermoelectricity in molecular junctions.

    PubMed

    Reddy, Pramod; Jang, Sung-Yeon; Segalman, Rachel A; Majumdar, Arun

    2007-03-16

    By trapping molecules between two gold electrodes with a temperature difference across them, the junction Seebeck coefficients of 1,4-benzenedithiol (BDT), 4,4'-dibenzenedithiol, and 4,4''-tribenzenedithiol in contact with gold were measured at room temperature to be +8.7 +/- 2.1 microvolts per kelvin (muV/K), +12.9 +/- 2.2 muV/K, and +14.2 +/- 3.2 muV/K, respectively (where the error is the full width half maximum of the statistical distributions). The positive sign unambiguously indicates p-type (hole) conduction in these heterojunctions, whereas the Au Fermi level position for Au-BDT-Au junctions was identified to be 1.2 eV above the highest occupied molecular orbital level of BDT. The ability to study thermoelectricity in molecular junctions provides the opportunity to address these fundamental unanswered questions about their electronic structure and to begin exploring molecular thermoelectric energy conversion.

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

    PubMed Central

    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 (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. 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

  12. Dental Apical Papilla as Therapy for Spinal Cord Injury.

    PubMed

    De Berdt, P; Vanacker, J; Ucakar, B; Elens, L; Diogenes, A; Leprince, J G; Deumens, R; des Rieux, A

    2015-11-01

    Stem cells of the apical papilla (SCAP) represent great promise regarding treatment of neural tissue damage, such as spinal cord injury (SCI). They derive from the neural crest, express numerous neurogenic markers, and mediate neurite outgrowth and axonal targeting. The goal of the present work was to investigate for the first time their potential to promote motor recovery after SCI in a rat hemisection model when delivered in their original stem cell niche-that is, by transplantation of the human apical papilla tissue itself into the lesion. Control groups consisted of animals subjected to laminectomy only (shams) and to lesion either untreated or injected with a fibrin hydrogel with or without human SCAP. Basso-Beattie-Bresnahan locomotor scores at 1 and 3 d postsurgery confirmed early functional decline in all SCI groups. This significant impairment was reversed, as seen in CatWalk analyses, after transplantation of apical papilla into the injured spinal cord wound, whereas the other groups demonstrated persistent functional impairment. Moreover, tactile allodynia did not develop as an unwanted side effect in any of the groups, even though the SCAP hydrogel group showed higher expression of the microglial marker Iba-1, which has been frequently associated with allodynia. Notably, the apical papilla transplant group presented with reduced Iba-1 expression level. Masson trichrome and human mitochondria staining showed the preservation of the apical papilla integrity and the presence of numerous human cells, while human cells could no longer be detected in the SCAP hydrogel group at the 6-wk postsurgery time point. Altogether, our data suggest that the transplantation of a human apical papilla at the lesion site improves gait in spinally injured rats and reduces glial reactivity. It also underlines the potential interest for the application of delivering SCAP in their original niche, as compared with use of a fibrin hydrogel.

  13. Multiple idiopathic external apical root resorption: A rare case report

    PubMed Central

    Bansal, Parul; Nikhil, Vineeta; Kapur, Sonali

    2015-01-01

    Multiple idiopathic external apical root resorption (MIEARR) is a relatively rare condition affecting multiple teeth in a dentition. As the condition is nonsymptomatic, a case is usually detected as an incidental radiographic finding. However, it may cause pain and mobility in severe cases. It is sometimes self-limiting or sometimes may progress to tooth loss. This paper presents a case of external apical root resorption involving multiple teeth in which etiology was not identified, so idiopathic root resorption was considered as a diagnosis of exclusion. PMID:25657532

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

    PubMed

    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.

  15. Tight junctions in inflammatory bowel diseases and inflammatory bowel disease associated colorectal cancer

    PubMed Central

    Landy, Jonathan; Ronde, Emma; English, Nick; Clark, Sue K; Hart, Ailsa L; Knight, Stella C; Ciclitira, Paul J; Al-Hassi, Hafid Omar

    2016-01-01

    Inflammatory bowel diseases are characterised by inflammation that compromises the integrity of the epithelial barrier. The intestinal epithelium is not only a static barrier but has evolved complex mechanisms to control and regulate bacterial interactions with the mucosal surface. Apical tight junction proteins are critical in the maintenance of epithelial barrier function and control of paracellular permeability. The characterisation of alterations in tight junction proteins as key players in epithelial barrier function in inflammatory bowel diseases is rapidly enhancing our understanding of critical mechanisms in disease pathogenesis as well as novel therapeutic opportunities. Here we give an overview of recent literature focusing on the role of tight junction proteins, in particular claudins, in inflammatory bowel diseases and inflammatory bowel disease associated colorectal cancer. PMID:27003989

  16. Corneal endothelial cells possess an elaborate multipolar shape to maximize the basolateral to apical membrane area

    PubMed Central

    Harrison, Theresa A.; He, Zhiguo; Boggs, Kristin; Thuret, Gilles; Liu, Hong-Xiang

    2016-01-01

    Purpose The corneal endothelium is widely believed to consist of geometrically regular cells interconnected by junctional complexes. However, while en face visualization of the endothelial apical surface reveals characteristic polygonal borders, the overall form of the component cells has rarely been observed. Methods To visualize the shape of individual endothelial cells within the native monolayer, two independent Cre/LoxP-based cell labeling approaches were used. In the first, a P0-Cre mouse driver strain was bred to an R26-tdTomato reporter line to map neural crest–derived endothelial cells with cytosolic red fluorescent protein. In the second, HPRT-Cre induction of small numbers of green and red fluorescent protein–filled cells within a background of unlabeled cells was achieved using a dual-color reporter system, mosaic analysis with double markers (MADM). Selective imaging of the endothelial lateral membranes at different apicobasal levels was accomplished after staining with antibodies to ZO-1 and the neural cell adhesion molecule (NCAM). Results When viewed in their entirety in whole-mount preparations, fluorescent protein–filled cells appear star-shaped, extending multiple dendritic processes that radiate outward in the plane of the monolayer. Examination of rare cases where cells expressing different fluorescent proteins lie directly adjacent to one another reveals that these long processes undergo extensive interdigitation. The resulting overlap allows individual cells to extend over a greater area than if the cell boundaries were mutually exclusive. Anti-NCAM staining of these interlocking peripheral cell extensions reveals an elaborate system of lateral membrane folds that, when viewed in optical sections, increase in complexity from the apical to the basal pole. This not only produces a substantial increase in the basolateral, relative to the apical, membrane but also greatly extends the paracellular pathway as a highly convoluted space

  17. The Extracellular Architecture of Adherens Junctions Revealed by Crystal Structures of Type I Cadherins

    SciTech Connect

    O Harrison; X Jin; S Hong; F Bahna; G Ahlsen; J Brasch; Y Wu; J Vendome; K Felsovalyi; et al.

    2011-12-31

    Adherens junctions, which play a central role in intercellular adhesion, comprise clusters of type I classical cadherins that bind via extracellular domains extended from opposing cell surfaces. We show that a molecular layer seen in crystal structures of E- and N-cadherin ectodomains reported here and in a previous C-cadherin structure corresponds to the extracellular architecture of adherens junctions. In all three ectodomain crystals, cadherins dimerize through a trans adhesive interface and are connected by a second, cis, interface. Assemblies formed by E-cadherin ectodomains coated on liposomes also appear to adopt this structure. Fluorescent imaging of junctions formed from wild-type and mutant E-cadherins in cultured cells confirm conclusions derived from structural evidence. Mutations that interfere with the trans interface ablate adhesion, whereas cis interface mutations disrupt stable junction formation. Our observations are consistent with a model for junction assembly involving strong trans and weak cis interactions localized in the ectodomain.

  18. Regulation of neuronal axon specification by glia-neuron gap junctions in C. elegans

    PubMed Central

    Meng, Lingfeng; Zhang, Albert; Jin, Yishi; Yan, Dong

    2016-01-01

    Axon specification is a critical step in neuronal development, and the function of glial cells in this process is not fully understood. Here, we show that C. elegans GLR glial cells regulate axon specification of their nearby GABAergic RME neurons through GLR-RME gap junctions. Disruption of GLR-RME gap junctions causes misaccumulation of axonal markers in non-axonal neurites of RME neurons and converts microtubules in those neurites to form an axon-like assembly. We further uncover that GLR-RME gap junctions regulate RME axon specification through activation of the CDK-5 pathway in a calcium-dependent manner, involving a calpain clp-4. Therefore, our study reveals the function of glia-neuron gap junctions in neuronal axon specification and shows that calcium originated from glial cells can regulate neuronal intracellular pathways through gap junctions. DOI: http://dx.doi.org/10.7554/eLife.19510.001 PMID:27767956

  19. Testicular cell junction: a novel target for male contraception.

    PubMed

    Lee, Nikki P Y; Wong, Elissa W P; Mruk, Dolores D; Cheng, C Yan

    2009-01-01

    Even though various contraceptive methods are widely available, the number of unwanted pregnancies is still on the rise in developing countries, pressurizing the already resource limited nations. One of the major underlying reasons is the lack of effective, low cost, and safe contraceptives for couples. During the past decade, some studies were performed using animal models to decipher if the Sertoli-germ cell junction in the testis is a target for male fertility regulation. Some of these study models were based on the use of hormones and/or chemicals to disrupt the hypothalamic-pituitary-testicular axis (e.g., androgen-based implants or pills) and others utilized a panel of chemical entities or synthetic peptides to perturb spermatogenesis either reversibly or non-reversibly. Among them, adjudin, a potential male contraceptive, is one of the compounds exerting its action on the unique adherens junctions, known as ectoplasmic specializations, in the testis. Since the testis is equipped with inter-connected cell junctions, an initial targeting of one junction type may affect the others and these accumulative effects could lead to spermatogenic arrest. This review attempts to cover an innovative theme on how male infertility can be achieved by inducing junction instability and defects in the testis, opening a new window of research for male contraceptive development. While it will still take much time and effort of intensive investigation before a product can reach the consumable market, these findings have provided hope for better family planning involving men.

  20. Signatures of topological Josephson junctions

    NASA Astrophysics Data System (ADS)

    Peng, Yang; Pientka, Falko; Berg, Erez; Oreg, Yuval; von Oppen, Felix

    2016-08-01

    Quasiparticle poisoning and diabatic transitions may significantly narrow the window for the experimental observation of the 4 π -periodic dc Josephson effect predicted for topological Josephson junctions. Here, we show that switching-current measurements provide accessible and robust signatures for topological superconductivity which persist in the presence of quasiparticle poisoning processes. Such measurements provide access to the phase-dependent subgap spectrum and Josephson currents of the topological junction when incorporating it into an asymmetric SQUID together with a conventional Josephson junction with large critical current. We also argue that pump-probe experiments with multiple current pulses can be used to measure the quasiparticle poisoning rates of the topological junction. The proposed signatures are particularly robust, even in the presence of Zeeman fields and spin-orbit coupling, when focusing on short Josephson junctions. Finally, we also consider microwave excitations of short topological Josephson junctions which may complement switching-current measurements.

  1. Ultrastructural studies of the junctional complex in the musculature of the arrow-worm (Sagitta setosa) (Chaetognatha).

    PubMed

    Duvert, M; Gros, D; Salat, C

    1980-01-01

    In the A fibres of the primary musculature of Sagitta, the junctional complex is made up of three kinds of junctions. From the apex to the base they occur in the following order: an apical zonula adherens, a columnar zonula then columnar maculae intermingled with gap junction. Each columnar junction joins two intracellular filament networks in adjacent cells; this cytoskeleton is largely developed around the nucleus of the A fibres and in close relation with the contractile apparatus, especially at the I band level. The B fibres, which never reach the general cavity, lack zonula adherens and columnar zonula. The columnar junction constitutes a new type of junction which seems to belong to the adherens kind. At their level fibrous columns cross the extracellular space, joining the membranes. Each column faces two cytoplasmic densities localized against the cytoplasmic leaflets of the membranes. A cytoskeleton composed of bunldes of cytoplasmic filaments is in close contact with these cytoplasmic densities. The great number of columnar junctions and associated cytoskeleton assure the cohesion of the tissue and the distribution of contractile forces in the absence of connective tissue. The abundance of gap junctions can account for the metabolic and ionic coupling of the fibres.

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

    PubMed

    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

  3. The ITPA disruption database

    NASA Astrophysics Data System (ADS)

    Eidietis, N. W.; Gerhardt, S. P.; Granetz, R. S.; Kawano, Y.; Lehnen, M.; Lister, J. B.; Pautasso, G.; Riccardo, V.; Tanna, R. L.; Thornton, A. J.; ITPA Disruption Database Participants, The

    2015-06-01

    A multi-device database of disruption characteristics has been developed under the auspices of the International Tokamak Physics Activity magneto-hydrodynamics topical group. The purpose of this ITPA disruption database (IDDB) is to find the commonalities between the disruption and disruption mitigation characteristics in a wide variety of tokamaks in order to elucidate the physics underlying tokamak disruptions and to extrapolate toward much larger devices, such as ITER and future burning plasma devices. In contrast to previous smaller disruption data collation efforts, the IDDB aims to provide significant context for each shot provided, allowing exploration of a wide array of relationships between pre-disruption and disruption parameters. The IDDB presently includes contributions from nine tokamaks, including both conventional aspect ratio and spherical tokamaks. An initial parametric analysis of the available data is presented. This analysis includes current quench rates, halo current fraction and peaking, and the effectiveness of massive impurity injection. The IDDB is publicly available, with instruction for access provided herein.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  5. Theory of Electric Resonance in the Neocortical Apical Dendrite

    PubMed Central

    Kasevich, Ray S.; LaBerge, David

    2011-01-01

    Pyramidal neurons of the neocortex display a wide range of synchronous EEG rhythms, which arise from electric activity along the apical dendrites of neocortical pyramidal neurons. Here we present a theoretical description of oscillation frequency profiles along apical dendrites which exhibit resonance frequencies in the range of 10 to 100 Hz. The apical dendrite is modeled as a leaky coaxial cable coated with a dielectric, in which a series of compartments act as coupled electric circuits that gradually narrow the resonance profile. The tuning of the peak frequency is assumed to be controlled by the average amplitude of voltage-gated outward currents, which in turn are regulated by the subthreshold noise in the thousands of synaptic spines that are continuously bombarded by local circuits. The results of simulations confirmed the ability of the model both to tune the peak frequency in the 10–100 Hz range and to gradually narrow the resonance profile. Considerable additional narrowing of the resonance profile is provided by repeated looping through the apical dendrite via the corticothalamocortical circuit, which reduced the width of each resonance curve (at half-maximum) to approximately 1 Hz. Synaptic noise in the neural circuit is discussed in relation to the ways it can influence the narrowing process. PMID:21853129

  6. Unilateral apical infiltrate as an initial presentation of pulmonary sarcoidosis.

    PubMed

    Tice, A W

    1981-11-01

    A unilateral, apical, pulmonary infiltrate was seen in an Air Force weapon systems officer stationed in the Philippines as an initial presentation of pulmonary sarcoidosis. The most obvious diagnosis for that geographic area is tuberculosis. Diagnosis must be pursued to evaluate all differential possibilities, with resort to open-lung or bronchoscopic biopsy, if necessary.

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

    PubMed

    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.

  8. Theory of electric resonance in the neocortical apical dendrite.

    PubMed

    Kasevich, Ray S; LaBerge, David

    2011-01-01

    Pyramidal neurons of the neocortex display a wide range of synchronous EEG rhythms, which arise from electric activity along the apical dendrites of neocortical pyramidal neurons. Here we present a theoretical description of oscillation frequency profiles along apical dendrites which exhibit resonance frequencies in the range of 10 to 100 Hz. The apical dendrite is modeled as a leaky coaxial cable coated with a dielectric, in which a series of compartments act as coupled electric circuits that gradually narrow the resonance profile. The tuning of the peak frequency is assumed to be controlled by the average amplitude of voltage-gated outward currents, which in turn are regulated by the subthreshold noise in the thousands of synaptic spines that are continuously bombarded by local circuits. The results of simulations confirmed the ability of the model both to tune the peak frequency in the 10-100 Hz range and to gradually narrow the resonance profile. Considerable additional narrowing of the resonance profile is provided by repeated looping through the apical dendrite via the corticothalamocortical circuit, which reduced the width of each resonance curve (at half-maximum) to approximately 1 Hz. Synaptic noise in the neural circuit is discussed in relation to the ways it can influence the narrowing process.

  9. An induced junction photovoltaic cell

    NASA Technical Reports Server (NTRS)

    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. GUARD RING SEMICONDUCTOR JUNCTION

    DOEpatents

    Goulding, F.S.; Hansen, W.L.

    1963-12-01

    A semiconductor diode having a very low noise characteristic when used under reverse bias is described. Surface leakage currents, which in conventional diodes greatly contribute to noise, are prevented from mixing with the desired signal currents. A p-n junction is formed with a thin layer of heavily doped semiconductor material disposed on a lightly doped, physically thick base material. An annular groove cuts through the thin layer and into the base for a short distance, dividing the thin layer into a peripheral guard ring that encircles the central region. Noise signal currents are shunted through the guard ring, leaving the central region free from such currents. (AEC)

  11. YBCO Josephson Junction Arrays

    DTIC Science & Technology

    1993-07-14

    Also, CaRuO 3 is chemically compatible with YBa2Cu30 7 and its conductivity does not appear to be strongly dependent on doping or oxygen concentration...barrier conductivity is quite high. The first YBa2Cu30 7 layer and the SrTiO3 layer are deposited first and then patterned with ion milling (to help form...the edge junction will dominate any leakage through the SrTiO3 , thus the integrity of that dielectric will not be a concern here. The integrity of the

  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

    PubMed Central

    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. Lipid rafts are disrupted in mildly inflamed intestinal microenvironments without overt disruption of the epithelial barrier.

    PubMed

    Bowie, Rachel V; Donatello, Simona; Lyes, Clíona; Owens, Mark B; Babina, Irina S; Hudson, Lance; Walsh, Shaun V; O'Donoghue, Diarmuid P; Amu, Sylvie; Barry, Sean P; Fallon, Padraic G; Hopkins, Ann M

    2012-04-15

    Intestinal epithelial barrier disruption is a feature of inflammatory bowel disease (IBD), but whether barrier disruption precedes or merely accompanies inflammation remains controversial. Tight junction (TJ) adhesion complexes control epithelial barrier integrity. Since some TJ proteins reside in cholesterol-enriched regions of the cell membrane termed lipid rafts, we sought to elucidate the relationship between rafts and intestinal epithelial barrier function. Lipid rafts were isolated from Caco-2 intestinal epithelial cells primed with the proinflammatory cytokine interferon-γ (IFN-γ) or treated with methyl-β-cyclodextrin as a positive control for raft disruption. Rafts were also isolated from the ilea of mice in which colitis had been induced in conjunction with in vivo intestinal permeability measurements, and lastly from intestinal biopsies of ulcerative colitis (UC) patients with predominantly mild or quiescent disease. Raft distribution was analyzed by measuring activity of the raft-associated enzyme alkaline phosphatase and by performing Western blot analysis for flotillin-1. Epithelial barrier integrity was estimated by measuring transepithelial resistance in cytokine-treated cells or in vivo permeability to fluorescent dextran in colitic mice. Raft and nonraft fractions were analyzed by Western blotting for the TJ proteins occludin and zonula occludens-1 (ZO-1). Our results revealed that lipid rafts were disrupted in IFN-γ-treated cells, in the ilea of mice with subclinical colitis, and in UC patients with quiescent inflammation. This was not associated with a clear pattern of occludin or ZO-1 relocalization from raft to nonraft fractions. Significantly, a time-course study in colitic mice revealed that disruption of lipid rafts preceded the onset of increased intestinal permeability. Our data suggest for the first time that lipid raft disruption occurs early in the inflammatory cascade in murine and human colitis and, we speculate, may contribute to

  14. Crumbs 3b promotes tight junctions in an ezrin-dependent manner in mammalian cells

    PubMed Central

    Tilston-Lünel, Andrew M.; Haley, Kathryn E.; Schlecht, Nicolas F.; Wang, Yanhua; Chatterton, Abigail L.D.; Moleirinho, Susana; Watson, Ailsa; Hundal, Harinder S.; Prystowsky, Michael B.; Gunn-Moore, Frank J.; Reynolds, Paul A.

    2016-01-01

    Crumbs 3 (CRB3) is a component of epithelial junctions, which has been implicated in apical-basal polarity, apical identity, apical stability, cell adhesion, and cell growth. CRB3 undergoes alternative splicing to yield two variants: CRB3a and CRB3b. Here, we describe novel data demonstrating that, as with previous studies on CRB3a, CRB3b also promotes the formation of tight junctions (TJs). However, significantly we demonstrate that the 4.1-ezrin–radixin–moesin-binding motif of CRB3b is required for CRB3b functionality and that ezrin binds to the FBM of CRB3b. Furthermore, we show that ezrin contributes to CRB3b functionality and the correct distribution of TJ proteins. We demonstrate that both CRB3 isoforms are required for the production of functionally mature TJs and also the localization of ezrin to the plasma membrane. Finally, we demonstrate that reduced CRB3b expression in head and neck squamous cell carcinoma (HNSCC) correlates with cytoplasmic ezrin, a biomarker for aggressive disease, and shows evidence that while CRB3a expression has no effect, low CRB3b and high cytoplasmic ezrin expression combined may be prognostic for HNSCC. PMID:27190314

  15. An unusual ST-segment elevation: apical hypertrophic cardiomyopathy shows the ace up its sleeve.

    PubMed

    de Santis, Francesco; Pergolini, Amedeo; Zampi, Giordano; Pero, Gaetano; Pino, Paolo Giuseppe; Minardi, Giovanni

    2013-01-01

    Apical hypertrophic cardiomyopathy is part of the broad clinical and morphologic spectrum of hypertrophic cardiomyopathy. We report a patient with electrocardiographic abnormalities in whom acute coronary syndrome was excluded and apical hypertrophic cardiomyopathy was demonstrated by careful differential diagnosis.

  16. Alcohol disrupts sleep homeostasis.

    PubMed

    Thakkar, Mahesh M; Sharma, Rishi; Sahota, Pradeep

    2015-06-01

    Alcohol is a potent somnogen and one of the most commonly used "over the counter" sleep aids. In healthy non-alcoholics, acute alcohol decreases sleep latency, consolidates and increases the quality (delta power) and quantity of NREM sleep during the first half of the night. However, sleep is disrupted during the second half. Alcoholics, both during drinking periods and during abstinences, suffer from a multitude of sleep disruptions manifested by profound insomnia, excessive daytime sleepiness, and altered sleep architecture. Furthermore, subjective and objective indicators of sleep disturbances are predictors of relapse. Finally, within the USA, it is estimated that societal costs of alcohol-related sleep disorders exceeds $18 billion. Thus, although alcohol-associated sleep problems have significant economic and clinical consequences, very little is known about how and where alcohol acts to affect sleep. In this review, we have described our attempts to unravel the mechanism of alcohol-induced sleep disruptions. We have conducted a series of experiments using two different species, rats and mice, as animal models. We performed microdialysis, immunohistochemical, pharmacological, sleep deprivation and lesion studies which suggest that the sleep-promoting effects of alcohol may be mediated via alcohol's action on the mediators of sleep homeostasis: adenosine (AD) and the wake-promoting cholinergic neurons of the basal forebrain (BF). Alcohol, via its action on AD uptake, increases extracellular AD resulting in the inhibition of BF wake-promoting neurons. Since binge alcohol consumption is a highly prevalent pattern of alcohol consumption and disrupts sleep, we examined the effects of binge drinking on sleep-wakefulness. Our results suggest that disrupted sleep homeostasis may be the primary cause of sleep disruption observed following binge drinking. Finally, we have also shown that sleep disruptions observed during acute withdrawal, are caused due to impaired

  17. Tubulogenesis in a simple cell cord requires the formation of bi-apical cells through two discrete Par domains.

    PubMed

    Denker, Elsa; Bocina, Ivana; Jiang, Di

    2013-07-01

    Apico-basal polarization is a crucial step in the de novo formation of biological tubes. In Ciona notochord, tubulogenesis occurs in a single file of cells in the absence of cell proliferation. This configuration presents a unique challenge for the formation of a continuous lumen. Here, we show that this geometric configuration is associated with a novel polarization strategy: the generation of bipolar epithelial cells possessing two apical/luminal domains instead of one, as in the conventional epithelium. At the molecular level, cells establish two discrete Par3/Par6/aPKC patches, and form two sets of tight junctions, in opposite points of the cells. The key molecule controlling the formation of both domains is Par3. Changing the position of the cells within the organ fundamentally changes their polarity and the number of apical domains they develop. These results reveal a new mechanism for tubulogenesis from the simplest cell arrangement, which occurs in other developmental contexts, including vertebrate vascular anastomosis.

  18. Confronting the disruptive physician.

    PubMed

    Linney, B J

    1997-01-01

    Ignoring disruptive behavior is no longer an option in today's changing health care environment. Competition and managed care have caused more organizations to deal with the disruptive physician, rather than look the other way as many did in years past. But it's not an easy task, possibly the toughest of your management career. How should you confront a disruptive physician? By having clearly stated expectations for physician behavior and policies in place for dealing with problem physicians, organizations have a context from which to address the situation.

  19. Morphological analysis of the retrofilled apical dentin surfaces irradiated with CO2 laser

    NASA Astrophysics Data System (ADS)

    Aun, Carlos E.; Lage-Marques, Jose L.; Gavini, Giulio; Clasen, Naya F.; Matsumoto, Koukichi

    1998-04-01

    Countless researches conducted in these last years have compared the sealing capacity of various materials for retrofillings. Besides, the association of laser irradiation to traditional procedures inquires to increase the success of this kind of treatment. The purpose of this study was to evaluate the morphological changes on dentin surface and the junction between retrofilling material and apical cavity, with different materials irradiated or not with CO2 laser, in scanning electron microscopy. The following materials were used: Group A yields Super EBA; group B yields Super EBA and CO2 laser irradiation (Luxar System); group C yields Glass Ionomer Cement; group D yields Glass Ionomer Cement and CO2 laser. In groups B and D the power set was 2 watts, 20 msec, with a CT3105 ceramic point, and the power density for the CO2 laser application was 397,93 w/cm2. The morphological analysis permitted to conclude that the dentin laser irradiation showed different and less intense superficial alteration when compared with retrofilling materials. In most cases, the alterations to the material surfaces showed cavities and craters. Group B presented more irregular and affected surfaces, creating blank spaces in the adjacent areas to the radicular dentinal surfaces after laser application, probably because of the carbonization.

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

    PubMed

    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.

  1. Basolateral to apical transcytosis in polarized cells is indirect and involves BFA and trimeric G protein sensitive passage through the apical endosome

    PubMed Central

    1994-01-01

    We have used temperature and nocodazole blocks in an in vivo basolateral to apical transcytosis assay to dissociate the early transcytotic steps occurring during the formation of transcytotic vesicles and their microtubule-dependent translocation into the apical region, from the late steps when transcytotic cargo is delivered into the apical media. We found that polarized MDCK cells transfected with rabbit polymeric IgA receptor (pIgA-R) internalize basolaterally added pIgA-R ligand ([Fab]2 fragment of IgG against the receptor's ectodomain) at 17 degrees C but do not deliver it to the apical PM. Instead, the ligand accumulates in an apically localized transcytotic compartment, distal to the basolateral endosome and the microtubule- requiring translocation step. We have characterized this compartment and show that it is distinct from basolateral transferrin recycling endosomes, basolateral early endosomes or late endosomes or lysosomes. The apical transcytotic compartment colocalizes with the compartment containing apically recycling membrane markers (ricin and apically internalized pIgA-R ligand) but is distinct from the compartment receiving apically internalized fluid phase marker (BSA). This compartment is an intermediate station of the overall pathway since transcytotic ligand can exit the compartment and be released into the apical medium when cells preloaded at 17 degrees C are subsequently incubated at 37 degrees C. We have used this system to examine the effect of Brefeldin A (BFA) and the involvement of trimeric GTPases in the late (post apical transcytotic compartment) steps of the transcytotic pathway. We found that addition of BFA or cholera toxin, a known activator of Gs alpha, to cells preloaded with transcytotic ligand at 17 degrees C significantly inhibits the exit of ligand from the apical transcytotic compartment. General structure and function of the apical endosome are not affected since neither BFA nor cholera toxin inhibit the recycling of

  2. Apical organs in echinoderm larvae: insights into larval evolution in the Ambulacraria.

    PubMed

    Byrne, Maria; Nakajima, Yoko; Chee, Francis C; Burke, Robert D

    2007-01-01

    The anatomy and cellular organization of serotonergic neurons in the echinoderm apical organ exhibits class-specific features in dipleurula-type (auricularia, bipinnaria) and pluteus-type (ophiopluteus, echinopluteus) larvae. The apical organ forms in association with anterior ciliary structures. Apical organs in dipleurula-type larvae are more similar to each other than to those in either of the pluteus forms. In asteroid bipinnaria and holothuroid auricularia the apical organ spans ciliary band sectors that traverse the anterior-most end of the larvae. The asteroid apical organ also has prominent bilateral ganglia that connect with an apical network of neurites. The simple apical organ of the auricularia is similar to that in the hemichordate tornaria larva. Apical organs in pluteus forms differ markedly. The echinopluteus apical organ is a single structure on the oral hood between the larval arms comprised of two groups of cells joined by a commissure and its cell bodies do not reside in the ciliary band. Ophioplutei have a pair of lateral ganglia associated with the ciliary band of larval arms that may be the ophiuroid apical organ. Comparative anatomy of the serotonergic nervous systems in the dipleurula-type larvae of the Ambulacraria (Echinodermata+Hemichordata) suggests that the apical organ of this deuterostome clade originated as a simple bilaterally symmetric nerve plexus spanning ciliary band sectors at the anterior end of the larva. From this structure, the apical organ has been independently modified in association with the evolution of class-specific larval forms.

  3. Understanding disruptions in tokamaks

    NASA Astrophysics Data System (ADS)

    Zakharov, Leonid

    2011-10-01

    Disruptions in tokamaks are known since 1963 but even now some aspects of them remain a mystery. This talk describes progress made recently in understanding disruptions. A major step forward occurred in 2007 when the importance of galvanic contact of the plasma with the wall in plasma dynamics was pointed out. The toroidal asymmetry of plasma current, observed in JET vertical disruptions, was explained by the theory of the wall touching kink mode. The currents shared by the plasma with the wall and responsible for the asymmetry were identified as generated by the kink mode. Such currents are referred to as Hiro currents. They have shown exceptional consistency with the entire JET disruption data base (more than 5500 cases) and ruled out the long lasting interpretation based on ``halo currents,'' which contradict experiments even in the sign of the measured asymmetry. Accordingly, the sideways forces are understood and their scaling from JET to ITER was justified. Hiro currents provide also a plausible explanation of the current spike at the beginning of the disruptions. The important role of the plasma edge and its interaction with the wall was revealed. Based on this new understanding of disruptions, dedicated experiments on the current spike (J-TEXT, Wuhan, China) and runaway prevention by the repetitive triggering of kink modes (T-10, AUG, Tore Supra) were motivated and are in progress. Accordingly, the need for new, adaptive grid approaches to numerical simulations of disruptions became evident. In addition to the core MHD, simulations of realistic wall geometry, disruption specific plasma edge physics, plasma-wall interaction, and energetic particles need be developed. The first results of simulations of the fast MHD regime, Hiro current generation, and slower plasma decay due to a wall touching kink mode made with the new DSC code are presented. This work is supported by US DoE contract No. DE-AC02-09-CH11466.

  4. Ion bipolar junction transistors

    PubMed Central

    Tybrandt, Klas; Larsson, Karin C.; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-01-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated. PMID:20479274

  5. Ion bipolar junction transistors.

    PubMed

    Tybrandt, Klas; Larsson, Karin C; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-06-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated.

  6. Tight junction regulates epidermal calcium ion gradient and differentiation

    SciTech Connect

    Kurasawa, Masumi; Maeda, Tetsuo; Oba, Ai; Yamamoto, Takuya; Sasaki, Hiroyuki

    2011-03-25

    Research highlights: {yields} We disrupted epidermal tight junction barrier in reconstructed epidermis. {yields} It altered Ca{sup 2+} distribution and consequentially differentiation state as well. {yields} Tight junction should affect epidermal homeostasis by maintaining Ca{sup 2+} gradient. -- Abstract: It is well known that calcium ions (Ca{sup 2+}) induce keratinocyte differentiation. Ca{sup 2+} distributes to form a vertical gradient that peaks at the stratum granulosum. It is thought that the stratum corneum (SC) forms the Ca{sup 2+} gradient since it is considered the only permeability barrier in the skin. However, the epidermal tight junction (TJ) in the granulosum has recently been suggested to restrict molecular movement to assist the SC as a secondary barrier. The objective of this study was to clarify the contribution of the TJ to Ca{sup 2+} gradient and epidermal differentiation in reconstructed human epidermis. When the epidermal TJ barrier was disrupted by sodium caprate treatment, Ca{sup 2+} flux increased and the gradient changed in ion-capture cytochemistry images. Alterations of ultrastructures and proliferation/differentiation markers revealed that both hyperproliferation and precocious differentiation occurred regionally in the epidermis. These results suggest that the TJ plays a crucial role in maintaining epidermal homeostasis by controlling the Ca{sup 2+} gradient.

  7. Structural molecular components of septate junctions in cnidarians point to the origin of epithelial junctions in eukaryotes.

    PubMed

    Ganot, Philippe; Zoccola, Didier; Tambutté, Eric; Voolstra, Christian R; Aranda, Manuel; Allemand, Denis; Tambutté, Sylvie

    2015-01-01

    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.

  8. Aseptic multiplication of banana from excised floral apices.

    PubMed

    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.

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

    PubMed

    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.

  10. Dissection of neuronal gap junction circuits that regulate social behavior in Caenorhabditis elegans

    PubMed Central

    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

  11. Contour junctions underlie neural representations of scene categories in high-level human visual cortex.

    PubMed

    Choo, Heeyoung; Walther, Dirk B

    2016-07-15

    Humans efficiently grasp complex visual environments, making highly consistent judgments of entry-level category despite their high variability in visual appearance. How does the human brain arrive at the invariant neural representations underlying categorization of real-world environments? We here show that the neural representation of visual environments in scene-selective human visual cortex relies on statistics of contour junctions, which provide cues for the three-dimensional arrangement of surfaces in a scene. We manipulated line drawings of real-world environments such that statistics of contour orientations or junctions were disrupted. Manipulated and intact line drawings were presented to participants in an fMRI experiment. Scene categories were decoded from neural activity patterns in the parahippocampal place area (PPA), the occipital place area (OPA) and other visual brain regions. Disruption of junctions but not orientations led to a drastic decrease in decoding accuracy in the PPA and OPA, indicating the reliance of these areas on intact junction statistics. Accuracy of decoding from early visual cortex, on the other hand, was unaffected by either image manipulation. We further show that the correlation of error patterns between decoding from the scene-selective brain areas and behavioral experiments is contingent on intact contour junctions. Finally, a searchlight analysis exposes the reliance of visually active brain regions on different sets of contour properties. Statistics of contour length and curvature dominate neural representations of scene categories in early visual areas and contour junctions in high-level scene-selective brain regions.

  12. Ascus apical apparatus and ascospore characters in Xylariaceae.

    PubMed

    Suwannasai, Nuttika; Whalley, Margaret A; Whalley, Anthony J S; Thienhirun, Surang; Sihanonth, Prakitsin

    2012-12-01

    Members of Xylariaceae (Ascomycota) are recognized and classified mainly on the morphological features of their sexual state. In a number of genera high morphological variation of stromatal characters has made confident recognition of generic and specific boundaries difficult. There are, however, a range of microscopical characteristics which can in most cases make distinctions, especially at generic level, even in the absence of molecular data. These include details of the apical apparatus in the ascus (e.g. disc-shaped, inverted hat-shaped, rhomboid, composed of rings, amyloid, non-amyloid); position and length of the germ slit; and presence and type of ascospore wall ornamentation as seen by scanning electron microscopy (SEM). Unfortunately many of the classical studies on xylariaceous genera omitted these features and were undertaken long before the development of scanning electron microscopy. More recent studies have, however, demonstrated their value as diagnostic characters in the family. Camillea is for example, instantly recognizable by its rhomboid or diamond shaped apical apparatus, and the distinctive inverted hat or urniform type is usually prominent in Xylaria, Rosellinia, Kretzschmaria, and Nemania. At least six categories of apical apparatus based on shape and size can be recognized. Ascospore ornamentation as seen by SEM has been exceptionally useful and provided the basis for separating Camillea from Biscogniauxia and other xylariaceous genera.

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

    PubMed Central

    Chaman, Chandrakar

    2016-01-01

    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. PMID:27656588

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Ontogenetic contingency of tolerance mechanisms in response to apical damage

    PubMed Central

    Gruntman, Michal; Novoplansky, Ariel

    2011-01-01

    Background and Aims Plants are able to tolerate tissue loss through vigorous branching which is often triggered by release from apical dominance and activation of lateral meristems. However, damage-induced branching might not be a mere physiological outcome of released apical dominance, but an adaptive response to environmental signals, such as damage timing and intensity. Here, branching responses to both factors were examined in the annual plant Medicago truncatula. Methods Branching patterns and allocation to reproductive traits were examined in response to variable clipping intensities and timings in M. truncatula plants from two populations that vary in the onset of reproduction. Phenotypic selection analysis was used to evaluate the strength and direction of selection on branching under the damage treatments. Key Results Plants of both populations exhibited an ontogenetic shift in tolerance mechanisms: while early damage induced greater meristem activation, late damage elicited investment in late-determined traits, including mean pod and seed biomass, and supported greater germination rates. Severe damage mostly elicited simultaneous development of multiple-order lateral branches, but this response was limited to early damage. Selection analyses revealed positive directional selection on branching in plants under early- compared with late- or no-damage treatments. Conclusions The results demonstrate that damage-induced meristem activation is an adaptive response that could be modified according to the plant's developmental stage, severity of tissue loss and their interaction, stressing the importance of considering these effects when studying plastic responses to apical damage. PMID:21873259

  17. An ion-transporting ATPase encodes multiple apical localization signals

    PubMed Central

    1993-01-01

    Epithelial cells accumulate distinct populations of membrane proteins at their two plasmalemmal domains. We have examined the molecular signals which specify the differential subcellular distributions of two closely related ion pumps. The Na,K-ATPase is normally restricted to the basolateral membranes of numerous epithelial cell types, whereas the H,K-ATPase is a component of the apical surfaces of the parietal cells of the gastric epithelium. We have expressed full length and chimeric H,K-ATPase/Na,K-ATPase cDNAs in polarized renal proximal tubular epithelial cells (LLC-PK1). We find that both the alpha and beta subunits of the H,K-ATPase encode independent signals that specify apical localization. Furthermore, the H,K-ATPase beta-subunit possesses a sequence which mediates its participation in the endocytic pathway. The interrelationship between epithelial sorting and endocytosis signals suggested by these studies supports the redefinition of apical and basolateral as functional, rather than simply topographic domains. PMID:8385670

  18. Automatic detection of apical roots in oral radiographs

    NASA Astrophysics Data System (ADS)

    Wu, Yi; Xie, Fangfang; Yang, Jie; Cheng, Erkang; Megalooikonomou, Vasileios; Ling, Haibin

    2012-03-01

    The apical root regions play an important role in analysis and diagnosis of many oral diseases. Automatic detection of such regions is consequently the first step toward computer-aided diagnosis of these diseases. In this paper we propose an automatic method for periapical root region detection by using the state-of-theart machine learning approaches. Specifically, we have adapted the AdaBoost classifier for apical root detection. One challenge in the task is the lack of training cases especially for diseased ones. To handle this problem, we boost the training set by including more root regions that are close to the annotated ones and decompose the original images to randomly generate negative samples. Based on these training samples, the Adaboost algorithm in combination with Haar wavelets is utilized in this task to train an apical root detector. The learned detector usually generates a large amount of true and false positives. In order to reduce the number of false positives, a confidence score for each candidate detection result is calculated for further purification. We first merge the detected regions by combining tightly overlapped detected candidate regions and then we use the confidence scores from the Adaboost detector to eliminate the false positives. The proposed method is evaluated on a dataset containing 39 annotated digitized oral X-Ray images from 21 patients. The experimental results show that our approach can achieve promising detection accuracy.

  19. MicroRNAs regulate tight junction proteins and modulate epithelial/endothelial barrier functions

    PubMed Central

    Cichon, Christoph; Sabharwal, Harshana; Rüter, Christian; Schmidt, M Alexander

    2014-01-01

    Tightly controlled epithelial and endothelial barriers are a prerequisite for life as these barriers separate multicellular organisms from their environment and serve as first lines of defense. Barriers between neighboring epithelial cells are formed by multiple intercellular junctions including the ‘apical junctional complex—AJC’ with tight junctions (TJ), adherens junctions (AJ), and desmosomes. TJ consist of tetraspan transmembrane proteins like occludin, various claudins that directly control paracellular permeability, and the ‘Junctional Adhesion Molecules’ (JAMs). For establishing tight barriers TJ are essential but at the same time have to allow also selective permeability. For this, TJ need to be tightly regulated and controlled. This is organized by a variety of adaptor molecules, i.e., protein kinases, phosphatases and GTPases, which in turn are regulated and fine-tuned involving microRNAs (miRNAs). In this review we summarize available data on the role and targeting of miRNAs in the maintenance of epithelial and/or endothelial barriers. PMID:25610754

  20. Control of E-cadherin apical localisation and morphogenesis by a SOAP-1/AP-1/clathrin pathway in C. elegans epidermal cells.

    PubMed

    Gillard, Ghislain; Shafaq-Zadah, Massiullah; Nicolle, Ophélie; Damaj, Raghida; Pécréaux, Jacques; Michaux, Grégoire

    2015-05-01

    E-cadherin (E-cad) is the main component of epithelial junctions in multicellular organisms, where it is essential for cell-cell adhesion. The localisation of E-cad is often strongly polarised in the apico-basal axis. However, the mechanisms required for its polarised distribution are still largely unknown. We performed a systematic RNAi screen in vivo to identify genes required for the strict E-cad apical localisation in C. elegans epithelial epidermal cells. We found that the loss of clathrin, its adaptor AP-1 and the AP-1 interactor SOAP-1 induced a basolateral localisation of E-cad without affecting the apico-basal diffusion barrier. We further found that SOAP-1 controls AP-1 localisation, and that AP-1 is required for clathrin recruitment. Finally, we also show that AP-1 controls E-cad apical delivery and actin organisation during embryonic elongation, the final morphogenetic step of embryogenesis. We therefore propose that a molecular pathway, containing SOAP-1, AP-1 and clathrin, controls the apical delivery of E-cad and morphogenesis.

  1. Proliferative response of cells of the dentogingival junction to mechanical stimulation.

    PubMed

    Zentner, A; Heaney, T G; Sergl, H G

    2000-12-01

    The aim of this research was to study the proliferative response of junctional epithelium (JE) and gingival connective tissue (GCT) to mechanical stimulation in vivo with regard to the potential occurrence of apical migration of JE and loss of GCT attachment during orthodontic tooth movement. Elastic bands were inserted between the maxillary first and second molars of male rats aged 8 weeks, which were pulse-labelled with 3H-thymidine and subsequently killed in groups, together with labelled control animals (a total of 98 rats) after periods of 1-168 hours. Autoradiographs were prepared from plastic mesiodistal sections, and parameters of cell proliferation for JE and GCT of the papilla between the second and third molars were determined. Although the distance between the apical limit of JE and the most coronal periodontal ligament (PDL) fibres decreased on the pressure and increased on the tension sides of mechanically stimulated animals, the total cross-sectional area of JE remained unchanged compared with controls. In the basal and suprabasal layers of JE, cell proliferation was reduced on the pressure side and showed no change on the tension side. In the apical JE compartments on both sides, mechanical stressing resulted in lower proliferative activity. Cell proliferation in GCT adjacent to JE in stimulated animals did not differ from the corresponding controls. JE rapidly adapted to mechanical stimulation by means of differential local adjustments of cell proliferation without an occurrence of apical migration or hyperplasia. GCT cells in the vicinity of JE maintained their steady-state proliferative activity. These results do not support the concept that orthodontic tooth movement might per se have detrimental effects on the stability of the dentogingival junction.

  2. Thermopower measurements in molecular junctions.

    PubMed

    Rincón-García, Laura; Evangeli, Charalambos; Rubio-Bollinger, Gabino; Agraït, Nicolás

    2016-08-07

    The measurement of thermopower in molecular junctions offers complementary information to conductance measurements and is becoming essential for the understanding of transport processes at the nanoscale. In this review, we discuss the recent advances in the study of the thermoelectric properties of molecular junctions. After presenting the theoretical background for thermoelectricity at the nanoscale, we review the experimental techniques for measuring the thermopower in these systems and discuss the main results. Finally, we consider the challenges in the application of molecular junctions in viable thermoelectric devices.

  3. Polarized delivery of viral glycoproteins to the apical and basolateral plasma membranes of Madin-Darby canine kidney cells infected with temperature-sensitive viruses

    PubMed Central

    1985-01-01

    The intracellular route followed by viral envelope glycoproteins in polarized Madin-Darby canine kidney cells was studied by using temperature-sensitive mutants of vesicular stomatitis virus (VSV) and influenza, in which, at the nonpermissive temperature (39.5 degrees C), the newly synthesized glycoproteins (G proteins) and hemagglutinin (HA), respectively, are not transported out of the endoplasmic reticulum. After infection with VSV and incubation at 39.5 degrees C for 4-5 h, synchronous transfer of G protein to the plasma membrane was initiated by shifting to the permissive temperature (32.5 degrees C). Immunoelectron microscopy showed that under these conditions the protein moved to the Golgi apparatus and from there directly to a region of the lateral plasma membrane near this organelle. G protein then seemed to diffuse progressively to basal regions of the cell surface and, only after it had accumulated in the basolateral domain, it began to appear on the apical surface near the intercellular junctions. The results of these experiments indicate that the VSV G protein must be sorted before its arrival at the cell surface, and suggest that passage to the apical domain occurs only late in infection when tight junctions are no longer an effective barrier. In complementary experiments, using the temperature-sensitive mutant of influenza, cultures were first shifted from the nonpermissive temperature (39.5 degrees C) to 18.5 degrees C, to allow entrance of the glycoprotein into the Golgi apparatus (see Matlin, K.S., and K. Simons, 1983, Cell, 34:233-243). Under these conditions HA accumulated in Golgi stacks and vesicles but did not reach the plasma membrane. When the temperature was subsequently shifted to 32.5 degrees C, HA rapidly appeared in discrete regions of the apical surface near, and often directly above, the Golgi elements, and later diffused throughout this surface. To ensure that the anti-HA antibodies had access to lateral domains, monolayers were

  4. Multiphoton imaging the disruptive nature of sulfur mustard lesions

    NASA Astrophysics Data System (ADS)

    Werrlein, Robert J.; Braue, Catherine R.; Dillman, James F.

    2005-03-01

    Sulfur mustard [bis-2-chloroethyl sulfide] is a vesicating agent first used as a weapon of war in WWI. It causes debilitating blisters at the epidermal-dermal junction and involves molecules that are also disrupted by junctional epidermolysis bullosa (JEB) and other blistering skin diseases. Despite its recurring use in global conflicts, there is still no completely effective treatment. We have shown by imaging human keratinocytes in cell culture and in intact epidermal tissues that the basal cells of skin contain well-organized molecules (keratins K5/K14, α6β4 integrin, laminin 5 and α3β1 integrin) that are early targets of sulfur mustard. Disruption and collapse of these molecules is coincident with nuclear displacement, loss of functional asymmetry, and loss of polarized mobility. The progression of this pathology precedes basal cell detachment by 8-24 h, a time equivalent to the "clinical latent phase" that defines the extant period between agent exposure and vesication. Our images indicate that disruption of adhesion-complex molecules also impairs cytoskeletal proteins and the integration of structures required for signal transduction and tissue repair. We have recently developed an optical system to test this hypothesis, i.e., to determine whether and how the early disruption of target molecules alters signal transduction. This environmentally controlled on-line system provides a nexus for real-time correlation of imaged lesions with DNA microarray analysis, and for using multiphoton microscopy to facilitate development of more effective treatment strategies.

  5. Keratin 76 is required for tight junction function and maintenance of the skin barrier.

    PubMed

    DiTommaso, Tia; Cottle, Denny L; Pearson, Helen B; Schlüter, Holger; Kaur, Pritinder; Humbert, Patrick O; Smyth, Ian M

    2014-10-01

    Keratins are cytoskeletal intermediate filament proteins that are increasingly being recognised for their diverse cellular functions. Here we report the consequences of germ line inactivation of Keratin 76 (Krt76) in mice. Homozygous disruption of this epidermally expressed gene causes neonatal skin flaking, hyperpigmentation, inflammation, impaired wound healing, and death prior to 12 weeks of age. We show that this phenotype is associated with functionally defective tight junctions that are characterised by mislocalization of the integral protein CLDN1. We further demonstrate that KRT76 interacts with CLDN1 and propose that this interaction is necessary to correctly position CLDN1 in tight junctions. The mislocalization of CLDN1 has been associated in various dermopathies, including the inflammatory disease, psoriasis. These observations establish a previously unknown connection between the intermediate filament cytoskeleton network and tight junctions and showcase Krt76 null mice as a possible model to study aberrant tight junction driven skin diseases.

  6. Keratin 76 Is Required for Tight Junction Function and Maintenance of the Skin Barrier

    PubMed Central

    DiTommaso, Tia; Cottle, Denny L.; Pearson, Helen B.; Schlüter, Holger; Kaur, Pritinder; Humbert, Patrick O.; Smyth, Ian M.

    2014-01-01

    Keratins are cytoskeletal intermediate filament proteins that are increasingly being recognised for their diverse cellular functions. Here we report the consequences of germ line inactivation of Keratin 76 (Krt76) in mice. Homozygous disruption of this epidermally expressed gene causes neonatal skin flaking, hyperpigmentation, inflammation, impaired wound healing, and death prior to 12 weeks of age. We show that this phenotype is associated with functionally defective tight junctions that are characterised by mislocalization of the integral protein CLDN1. We further demonstrate that KRT76 interacts with CLDN1 and propose that this interaction is necessary to correctly position CLDN1 in tight junctions. The mislocalization of CLDN1 has been associated in various dermopathies, including the inflammatory disease, psoriasis. These observations establish a previously unknown connection between the intermediate filament cytoskeleton network and tight junctions and showcase Krt76 null mice as a possible model to study aberrant tight junction driven skin diseases. PMID:25340345

  7. Emerging and Disruptive Technologies

    PubMed Central

    2016-01-01

    Several emerging or disruptive technologies can be identified that might, at some point in the future, displace established laboratory medicine technologies and practices. These include increased automation in the form of robots, 3-D printing, technology convergence (e.g., plug-in glucose meters for smart phones), new point-of-care technologies (e.g., contact lenses with sensors, digital and wireless enabled pregnancy tests) and testing locations (e.g., Retail Health Clinics, new at-home testing formats), new types of specimens (e.g., cell free DNA), big biology/data (e.g., million genome projects), and new regulations (e.g., for laboratory developed tests). In addition, there are many emerging technologies (e.g., planar arrays, mass spectrometry) that might find even broader application in the future and therefore also disrupt current practice. One interesting source of disruptive technology may prove to be the Qualcomm Tricorder XPrize, currently in its final stages. PMID:27683538

  8. Emerging and Disruptive Technologies.

    PubMed

    Kricka, Larry J

    2016-08-01

    Several emerging or disruptive technologies can be identified that might, at some point in the future, displace established laboratory medicine technologies and practices. These include increased automation in the form of robots, 3-D printing, technology convergence (e.g., plug-in glucose meters for smart phones), new point-of-care technologies (e.g., contact lenses with sensors, digital and wireless enabled pregnancy tests) and testing locations (e.g., Retail Health Clinics, new at-home testing formats), new types of specimens (e.g., cell free DNA), big biology/data (e.g., million genome projects), and new regulations (e.g., for laboratory developed tests). In addition, there are many emerging technologies (e.g., planar arrays, mass spectrometry) that might find even broader application in the future and therefore also disrupt current practice. One interesting source of disruptive technology may prove to be the Qualcomm Tricorder XPrize, currently in its final stages.

  9. The disruption management model.

    PubMed

    McAlister, James

    2011-10-01

    Within all organisations, business continuity disruptions present a set of dilemmas that managers may not have dealt with before in their normal daily duties. The disruption management model provides a simple but effective management tool to enable crisis management teams to stay focused on recovery in the midst of a business continuity incident. The model has four chronological primary headlines, which steer the team through a quick-time crisis decision-making process. The procedure facilitates timely, systematic, rationalised and justified decisions, which can withstand post-event scrutiny. The disruption management model has been thoroughly tested within an emergency services environment and is proven to significantly support clear and concise decision making in a business continuity context.

  10. Thermal conductance of superlattice junctions

    SciTech Connect

    Lu, Simon; McGaughey, Alan J. H.

    2015-05-15

    We use molecular dynamics simulations and the lattice-based scattering boundary method to compute the thermal conductance of finite-length Lennard-Jones superlattice junctions confined by bulk crystalline leads. The superlattice junction thermal conductance depends on the properties of the leads. For junctions with a superlattice period of four atomic monolayers at temperatures between 5 and 20 K, those with mass-mismatched leads have a greater thermal conductance than those with mass-matched leads. We attribute this lead effect to interference between and the ballistic transport of emergent junction vibrational modes. The lead effect diminishes when the temperature is increased, when the superlattice period is increased, and when interfacial disorder is introduced, but is reversed in the harmonic limit.

  11. Josephson junction Q-spoiler

    DOEpatents

    Clarke, J.; Hilbert, C.; Hahn, E.L.; Sleator, T.

    1986-03-25

    An automatic Q-spoiler comprising at least one Josephson tunnel junction connected in an LC circuit for flow of resonant current therethrough. When in use in a system for detecting the magnetic resonance of a gyromagnetic particle system, a high energy pulse of high frequency energy irradiating the particle system will cause the critical current through the Josephson tunnel junctions to be exceeded, causing the tunnel junctions to act as resistors and thereby damp the ringing of the high-Q detection circuit after the pulse. When the current has damped to below the critical current, the Josephson tunnel junctions revert to their zero-resistance state, restoring the Q of the detection circuit and enabling the low energy magnetic resonance signals to be detected.

  12. Josephson junction Q-spoiler

    DOEpatents

    Clarke, John; Hilbert, Claude; Hahn, Erwin L.; Sleator, Tycho

    1988-01-01

    An automatic Q-spoiler comprising at least one Josephson tunnel junction connected in an LC circuit for flow of resonant current therethrough. When in use in a system for detecting the magnetic resonance of a gyromagnetic particle system, a high energy pulse of high frequency energy irradiating the particle system will cause the critical current through the Josephson tunnel junctions to be exceeded, causing the tunnel junctions to act as resistors and thereby damp the ringing of the high-Q detection circuit after the pulse. When the current has damped to below the critical current, the Josephson tunnel junctions revert to their zero-resistance state, restoring the Q of the detection circuit and enabling the low energy magnetic resonance signals to be detected.

  13. Control of Junction Flow

    NASA Astrophysics Data System (ADS)

    Su, T.-C.; Bingham, C.; Kellier, L.

    2001-11-01

    Control for horseshoe vortices resulting from boundary layer separation in front of a structure has long been sought without satisfactory results. Tests were carried out in a water channel with the objective of seeking such a control. The water channel has a test section of .6m wide, .4m deep and 8m long, with an adjustable mean flow speed of up to .5m/s. Flow visualization technique was used to elucidate the flow process. To control the horseshoe vortex a long airfoil of 1cm chord was placed horizontally near the ground upstream of a 10cm thin square plate. It was found that the original horseshoe vortex moved toward and circulated around the airfoil. The junction flow immediately upstream of the obstacle was noticeably steady and free of disturbance. The process was insensitive to the streamwise location of the airfoil, horseshoe's vortical structure, stream speed and acceleration, upstream vortical influx, and magnitude/sign of airfoil's angle of attack. Experimental results with obliquely mounted square cylinder were similar, which demonstrated that controls were effective for all angles of attack.

  14. TNF-α and IFN-γ promote lymphocyte adhesion to endothelial junctional regions facilitating transendothelial migration.

    PubMed

    Jaczewska, Justyna; Abdulreda, Midhat H; Yau, Chi Y; Schmitt, Martin M; Schubert, Irene; Berggren, Per-Olof; Weber, Christian; Koenen, Rory R; Moy, Vincent T; Wojcikiewicz, Ewa P

    2014-02-01

    Inflammatory conditions induce redistribution of junctional adhesion receptors toward the apical regions of endothelial cells promoting lymphocyte TEM. Much of the molecular structures of TEM have been revealed; however, the biophysical mechanisms underlying this process remain to be fully elucidated. Here, we used immunofluorescence microscopy and AFM to study endothelial distribution of adhesion molecules upon lymphocyte activation and transmigration. Our immunofluorescence results revealed redistribution of JAM-A and PECAM-1 but not ICAM-1 or VCAM-1 toward the apical junctional regions of HUVECs following a 6-h stimulation with TNF-α and IFN-γ. Consistently, our SCFS studies revealed that Jurkat cell adhesion to stimulated HUVEC monolayers was significantly greater in junctional regions. Enhanced adhesion was mediated mostly by JAM-A receptors. Further AFM adhesion mapping of the homophilic JAM-A/JAM-A interaction on the surfaces of HUVECs revealed a greater number of JAM-A receptors available for binding along junctional regions after TNF-α and IFN-γ stimulation. Our data reveal for the first time that adhesion "hot spots" of JAM-A receptors are involved in initiating lymphocyte TEM under inflammatory conditions.

  15. Interruptions disrupt reading comprehension.

    PubMed

    Foroughi, Cyrus K; Werner, Nicole E; Barragán, Daniela; Boehm-Davis, Deborah A

    2015-06-01

    Previous research suggests that being interrupted while reading a text does not disrupt the later recognition or recall of information from that text. This research is used as support for Ericsson and Kintsch's (1995) long-term working memory (LT-WM) theory, which posits that disruptions while reading (e.g., interruptions) do not impair subsequent text comprehension. However, to fully comprehend a text, individuals may need to do more than recognize or recall information that has been presented in the text at a later time. Reading comprehension often requires individuals to connect and synthesize information across a text (e.g., successfully identifying complex topics such as themes and tones) and not just make a familiarity-based decision (i.e., recognition). The goal for this study was to determine whether interruptions while reading disrupt reading comprehension when the questions assessing comprehension require participants to connect and synthesize information across the passage. In Experiment 1, interruptions disrupted reading comprehension. In Experiment 2, interruptions disrupted reading comprehension but not recognition of information from the text. In Experiment 3, the addition of a 15-s time-out prior to the interruption successfully removed these negative effects. These data suggest that the time it takes to process the information needed to successfully comprehend text when reading is greater than that required for recognition. Any interference (e.g., an interruption) that occurs during the comprehension process may disrupt reading comprehension. This evidence supports the need for transient activation of information in working memory for successful text comprehension and does not support LT-WM theory.

  16. The disruptive radiologist.

    PubMed

    Ulreich, Sidney; Harris, Robert D; Sze, Gordon; Moriarity, Andrew K; Bluth, Edward

    2015-08-01

    Radiologists interact with many individuals during daily practice, including patients, technologists, and other physicians. Some interactions may potentially negatively affect patient care and are termed "disruptive" behaviors. These actions are not uncommon and may begin during training, long before a radiologist enters clinical practice. The causes of disruptive behavior are multifactorial, and it is important that educators and radiologists in practice alike be able to identify them and respond accordingly. An escalated approach for both trainees and practicing radiologists is recommended, with substantial penalties after each incident that can include termination of employment. Training programs and practices must have clearly defined methods for confronting this potentially time-consuming and difficult issue.

  17. Electronic thermometry in tunable tunnel junction

    DOEpatents

    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.

  18. Impact of early season apical meristem injury by gall inducing tipworm (Diptera: Cecidomyiidae) on reproductive and vegetative growth of cranberry.

    PubMed

    Tewari, S; Buonaccorsi, J P; Averill, A L

    2013-06-01

    Larvae of cranberry tipworm, Dasineura oxycoccana Johnson, disrupt early season growth of cranberry (Vaccinium macrocarpon Aiton) uprights or shoots by feeding on apical meristem tissue. A 2-yr field study was carried out at three different locations to determine the impact of tipworm feeding injury on the reproductive and vegetative growth of two cranberry cultivars ('Howes' and 'Stevens') in Massachusetts. In addition to tipworm-injured and intact control uprights, an artificial injury treatment simulating tipworm feeding was also included. Individual uprights of cranberry exhibited tolerance to natural (tipworm) and simulated apical meristem injury in the current growing season (fruit production) and results were corroborated by a greenhouse study. In the field study, weight of fruit was higher in tipworm-injured uprights as compared with intact control uprights at the sites with Howes. However, majority of injured uprights (tipworm and simulated) did not produce new growth from lateral buds (side-shoots) before the onset of dormancy. In the next growing season, fewer injured uprights resumed growth and produced flowers as compared with intact uprights at two of the three sites. We suggest that multiple-year studies focusing on whole plant response to tipworm herbivory will be required to determine the costs of chronic feeding injury over time.

  19. The Role of IRE-XBP1 Pathway in Regulation of Retinal Pigment Epithelium Tight Junctions

    PubMed Central

    Ma, Jacey H.; Wang, Joshua J.; Li, Junhua; Pfeffer, Bruce A.; Zhong, Yiming; Zhang, Sarah X.

    2016-01-01

    Purpose The retinal pigment epithelium (RPE) tight junctions play a pivotal role in maintaining the homeostatic environment of the neural retina. Herein, we investigated the role of X-box binding protein 1 (XBP1), an endoplasmic reticulum (ER) stress-responsive transcription factor, in regulation of RPE tight junctions. Methods Human RPE cell line (ARPE-19) and primary primate RPE cells were used for in vitro experiments and RPE-specific XBP1 knockout (KO) mice were used for in vivo study. Endoplasmic reticulum stress was induced by a sublethal dose of thapsigargin or tunicamycin. XBP1 activation was manipulated by IRE inhibitor 4μ8C, which suppresses XBP1 mRNA splicing. The integrity of tight junctions and the involvement of calcium-dependent RhoA/Rho kinase pathway were examined. Results Induction of ER stress by thapsigargin, but not tunicamycin, disrupted RPE tight junctions in ARPE-19 cells. Inhibition of XBP1 activation by 4μ8C resulted in a remarkable downregulation of tight junction proteins (ZO-1 and occludin) and defects in tight junction formation in the presence or absence of ER stress inducers. Overexpression of active XBP1 partially reversed 4μ8C-induced anomalies in tight junctions. Mechanistically, XBP1 inhibition resulted in increased intracellular Ca2+ concentration, upregulation of RhoA expression, redistribution of F-actin, and tight junction damage, which was attenuated by Rho kinase inhibitor Y27632. In vivo, deletion of XBP1 in the RPE resulted in defective RPE tight junctions accompanied by increased VEGF expression. Conclusions Taken together, these results suggest a protective role of XBP1 in maintaining RPE tight junctions possibly through regulation of calcium-dependent RhoA/Rho kinase signaling and actin cytoskeletal reorganization. PMID:27701635

  20. A Synthetic Peptide Corresponding to the Extracellular Domain of Occludin Perturbs the Tight Junction Permeability Barrier

    PubMed Central

    Wong, Vivian; Gumbiner, Barry M.

    1997-01-01

    Occludin, the putative tight junction integral membrane protein, is an attractive candidate for a protein that forms the actual sealing element of the tight junction. To study the role of occludin in the formation of the tight junction seal, synthetic peptides (OCC1 and OCC2) corresponding to the two putative extracellular domains of occludin were assayed for their ability to alter tight junctions in Xenopus kidney epithelial cell line A6. Transepithelial electrical resistance and paracellular tracer flux measurements indicated that the second extracellular domain peptide (OCC2) reversibly disrupted the transepithelial permeability barrier at concentrations of < 5 μM. Despite the increased paracellular permeability, there were no changes in gross epithelial cell morphology as determined by scanning EM. The OCC2 peptide decreased the amount of occludin present at the tight junction, as assessed by indirect immunofluorescence, as well as decreased total cellular content of occludin, as assessed by Western blot analysis. Pulse-labeling and metabolic chase analysis suggested that this decrease in occludin level could be attributed to an increase in turnover of cellular occludin rather than a decrease in occludin synthesis. The effect on occludin was specific because other tight junction components, ZO-1, ZO-2, cingulin, and the adherens junction protein E-cadherin, were unaltered by OCC2 treatment. Therefore, the peptide corresponding to the second extracellular domain of occludin perturbs the tight junction permeability barrier in a very specific manner. The correlation between a decrease in occludin levels and the perturbation of the tight junction permeability barrier provides evidence for a role of occludin in the formation of the tight junction seal. PMID:9015310

  1. Octagonal Defects at Carbon Nanotube Junctions

    PubMed Central

    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

  2. Alteration in synaptic junction proteins following traumatic brain injury.

    PubMed

    Merlo, Lucia; Cimino, Francesco; Angileri, Filippo Flavio; La Torre, Domenico; Conti, Alfredo; Cardali, Salvatore Massimiliano; Saija, Antonella; Germanò, Antonino

    2014-08-15

    Extensive research and scientific efforts have been focused on the elucidation of the pathobiology of cellular and axonal damage following traumatic brain injury (TBI). Conversely, few studies have specifically addressed the issue of synaptic dysfunction. Synaptic junction proteins may be involved in post-TBI alterations, leading to synaptic loss or disrupted plasticity. A Synapse Protein Database on synapse ontology identified 109 domains implicated in synaptic activities and over 5000 proteins, but few of these demonstrated to play a role in the synaptic dysfunction after TBI. These proteins are involved in neuroplasticity and neuromodulation and, most importantly, may be used as novel neuronal markers of TBI for specific intervention.

  3. Low Level Pro-inflammatory Cytokines Decrease Connexin36 Gap Junction Coupling in Mouse and Human Islets through Nitric Oxide-mediated Protein Kinase Cδ*

    PubMed Central

    Farnsworth, Nikki L.; Walter, Rachelle L.; Hemmati, Alireza; Westacott, Matthew J.; Benninger, Richard K. P.

    2016-01-01

    Pro-inflammatory cytokines contribute to the decline in islet function during the development of diabetes. Cytokines can disrupt insulin secretion and calcium dynamics; however, the mechanisms underlying this are poorly understood. Connexin36 gap junctions coordinate glucose-induced calcium oscillations and pulsatile insulin secretion across the islet. Loss of gap junction coupling disrupts these dynamics, similar to that observed during the development of diabetes. This study investigates the mechanisms by which pro-inflammatory cytokines mediate gap junction coupling. Specifically, as cytokine-induced NO can activate PKCδ, we aimed to understand the role of PKCδ in modulating cytokine-induced changes in gap junction coupling. Isolated mouse and human islets were treated with varying levels of a cytokine mixture containing TNF-α, IL-1β, and IFN-γ. Islet dysfunction was measured by insulin secretion, calcium dynamics, and gap junction coupling. Modulators of PKCδ and NO were applied to determine their respective roles in modulating gap junction coupling. High levels of cytokines caused cell death and decreased insulin secretion. Low levels of cytokine treatment disrupted calcium dynamics and decreased gap junction coupling, in the absence of disruptions to insulin secretion. Decreases in gap junction coupling were dependent on NO-regulated PKCδ, and altered membrane organization of connexin36. This study defines several mechanisms underlying the disruption to gap junction coupling under conditions associated with the development of diabetes. These mechanisms will allow for greater understanding of islet dysfunction and suggest ways to ameliorate this dysfunction during the development of diabetes. PMID:26668311

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

    PubMed Central

    Choudhary, Dinesh; Chaurasia, Amit Kumar; Kumar, S Mahesh; Arulkumar, Ajeet; Thajudeen, Anees; Namboodiri, Narayanan; Sanjay, G; Abhilash, SP; Ajitkumar, VK; JA, Tharakan

    2016-01-01

    Introduction: To study effects of various sites of right ventricular pacing lead implantation on left ventricular function by 2-dimensional (2D) speckle tracking for radial strain and LV dyssynchrony. Methods: This was retrospective prospective study. Fifteen patients each with right ventricular (RV) apical (RV apex and apical septum) and non-apical (mid septal and low right ventricular outflow tract [RVOT]) were programmed to obtain 100% ventricular pacing for evaluation by echo. Location and orientation of lead tip was noted and archived by fluoroscopy. Electrocardiography (ECG) was archived and 2D echo radial dyssynchrony was calculated. Results: The baseline data was similar between two groups. Intraventricular dyssynchrony was significantly more in apical location as compared to non-apical location (radial dyssynchrony: 108.2 ± 50.2 vs. 50.5 ± 24, P < 0.001; septal to posterior wall delay [SLWD] 63.5 ± 27.5 vs. 34 ± 10.7, P < 0.001, SPWD 112.5 ± 58.1 vs. 62.7 ± 12.1, P = 0.003). The left ventricular ejection fraction was decreased more in apical location than non apical location. Interventricular dyssynchrony was more in apical group but was not statistically significant. The QRS duration, QTc and lead thresholds were higher in apical group but not statistically significant. 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. PMID:27069563

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

    PubMed Central

    Dingsdag, Simon; Nelson, Stephen; Coleman, Nicholas V.

    2016-01-01

    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. PMID:27834171

  6. SEM investigation of Er:YAG laser apical preparation

    NASA Astrophysics Data System (ADS)

    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.

  7. Boomtowns and Lifeworld Disruption.

    ERIC Educational Resources Information Center

    England, J. Lynn; Albrect, Stan

    Three intermountain communities in Colorado and Utah were studied to determine the impact of rapid development on residents of rural communities, especially on their views of the world and their personal well-being, and to assess the degree to which energy boomtowns experience the social disruption suggested in the classical boomtown studies. Two…

  8. Membrane rafting: from apical sorting to phase segregation.

    PubMed

    Coskun, Unal; Simons, Kai

    2010-05-03

    In this review we describe the history of the development of the raft concept for membrane sub-compartmentalization. From its early beginnings as a mechanism for apical sorting in epithelial cells the concept has evolved to a general principle for membrane organisation. After a shaky start with crude methodology based on detergent extraction the field has become increasingly sophisticated, employing a host of different methods that support the existence of dynamic raft domains in membranes. These are composed of fluctuating nanoscale assemblies of sphingolipid, cholesterol and proteins that can be stabilized to coalesce, forming platforms that function in membrane signalling and trafficking.

  9. Progesterone-Based Intrauterine Device Use Is Associated with a Thinner Apical Layer of the Human Ectocervical Epithelium and a Lower ZO-1 mRNA Expression1

    PubMed Central

    Tjernlund, Annelie; Carias, Ann M.; Andersson, Sonia; Gustafsson-Sanchez, Susanna; Röhl, Maria; Petersson, Pernilla; Introini, Andrea; Hope, Thomas J.; Broliden, Kristina

    2015-01-01

    ABSTRACT Currently, whether hormonal contraceptives affect male to female human immunodeficiency virus (HIV) transmission is being debated. In this study, we investigated whether the use of progesterone-based intrauterine devices (pIUDs) is associated with a thinning effect on the ectocervical squamous epithelium, down-regulation of epithelial junction proteins, and/or alteration of HIV target cell distribution in the human ectocervix. Ectocervical tissue biopsies from healthy premenopausal volunteers using pIUDs were collected and compared to biopsies obtained from two control groups, namely women using combined oral contraceptives (COCs) or who do not use hormonal contraceptives. In situ staining and image analysis were used to measure epithelial thickness and the presence of HIV receptors in tissue biopsies. Messenger RNA levels of epithelial junction markers were measured by quantitative PCR. The epithelial thickness displayed by women in the pIUD group was similar to those in the COC group, but significantly thinner as compared to women in the no hormonal contraceptive group. The thinner epithelial layer of the pIUD group was specific to the apical layer of the ectocervix. Furthermore, the pIUD group expressed significantly lower levels of the tight junction marker ZO-1 within the epithelium as compared to the COC group. Similar expression levels of HIV receptors and coreceptors CD4, CCR5, DC-SIGN, and Langerin were observed in the three study groups. Thus, women using pIUD displayed a thinner apical layer of the ectocervical epithelium and reduced ZO-1 expression as compared to control groups. These data suggest that pIUD use may weaken the ectocervical epithelial barrier against invading pathogens, including HIV. PMID:25588510

  10. ClC-2 is required for rapid restoration of epithelial tight junctions in ischemic-injured murine jejunum

    SciTech Connect

    Nighot, Prashant K.; Moeser, Adam J.; Ryan, Kathleen A.; Ghashghaei, Troy; Blikslager, Anthony T.

    2009-01-01

    Background and aims: Involvement of the epithelial chloride channel ClC-2 has been implicated in barrier recovery following ischemic injury, possibly via a mechanism involving ClC-2 localization to the tight junction. The present study investigated mechanisms of intestinal barrier repair following ischemic injury in ClC-2{sup -/-} mice. Methods: Wild type, ClC-2 heterozygous and ClC-2{sup -/-} murine jejunal mucosa was subjected to complete ischemia, after which recovery of barrier function was monitored by measuring in vivo blood-to-lumen clearance of {sup 3}H-mannitol. Tissues were examined by light and electron microscopy. The role of ClC-2 in re-assembly of the tight junction during barrier recovery was studied by immunoblotting, immunolocalization and immunoprecipitation. Results: Following ischemic injury, ClC-2{sup -/-} mice had impaired barrier recovery compared to wild type mice, defined by increases in epithelial paracellular permeability independent of epithelial restitution. The recovering ClC-2{sup -/-} mucosa also had evidence of ultrastructural paracellular defects. The tight junction proteins occludin and claudin-1 shifted significantly to the detergent soluble membrane fraction during post-ischemic recovery in ClC-2{sup -/-} mice whereas wild type mice had a greater proportion of junctional proteins in the detergent insoluble fraction. Occludin was co-immunoprecipitated with ClC-2 in uninjured wild type mucosa, and the association between occludin and ClC-2 was re-established during ischemic recovery. Based on immunofluorescence studies, re-localization of occludin from diffuse sub-apical areas to apical tight junctions was impaired in ClC-2{sup -/-} mice. Conclusions: These data demonstrate a pivotal role of ClC-2 in recovery of the intestinal epithelium barrier by anchoring assembly of tight junctions following ischemic injury.

  11. Larval body patterning and apical organs are conserved in animal evolution

    PubMed Central

    2014-01-01

    Background Planktonic ciliated larvae are characteristic for the life cycle of marine invertebrates. Their most prominent feature is the apical organ harboring sensory cells and neurons of largely undetermined function. An elucidation of the relationships between various forms of primary larvae and apical organs is key to understanding the evolution of animal life cycles. These relationships have remained enigmatic due to the scarcity of comparative molecular data. Results To compare apical organs and larval body patterning, we have studied regionalization of the episphere, the upper hemisphere of the trochophore larva of the marine annelid Platynereis dumerilii. We examined the spatial distribution of transcription factors and of Wnt signaling components previously implicated in anterior neural development. Pharmacological activation of Wnt signaling with Gsk3β antagonists abolishes expression of apical markers, consistent with a repressive role of Wnt signaling in the specification of apical tissue. We refer to this Wnt-sensitive, six3- and foxq2-expressing part of the episphere as the ‘apical plate’. We also unraveled a molecular signature of the apical organ - devoid of six3 but expressing foxj, irx, nkx3 and hox - that is shared with other marine phyla including cnidarians. Finally, we characterized the cell types that form part of the apical organ by profiling by image registration, which allows parallel expression profiling of multiple cells. Besides the hox-expressing apical tuft cells, this revealed the presence of putative light- and mechanosensory as well as multiple peptidergic cell types that we compared to apical organ cell types of other animal phyla. Conclusions The similar formation of a six3+, foxq2+ apical plate, sensitive to Wnt activity and with an apical tuft in its six3-free center, is most parsimoniously explained by evolutionary conservation. We propose that a simple apical organ - comprising an apical tuft and a basal plexus

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

    PubMed

    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.

  13. Reticulated lipid probe fluorescence reveals MDCK cell apical membrane topography.

    PubMed

    Colarusso, Pina; Spring, Kenneth R

    2002-02-01

    High spatial resolution confocal microscopy of young MDCK cells stained with the lipophilic probe 1,1'-dihexadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiIC(16)) revealed a reticulated fluorescence pattern on the apical membrane. DiIC(16) was delivered as crystals to live cells to minimize possible solvent perturbations of the membrane lipids. The ratio of the integrated fluorescence intensities in the bright versus dim regions was 1.6 +/- 0.1 (n = 13). Deconvolved images of the cells were consistent with exclusive plasma membrane staining. Multi-spectral and fluorescence anisotropy microscopy did not reveal differences between bright and dim regions. Bright regions coincided with microvilli and microridges observed by differential interference contrast microscopy and were stable for several minutes. Fluorescence recovery after photobleaching yielded similar diffusion coefficients (pooled D = 1.5 +/- 0.6 x 10(-9) cm(2)/s, n = 40) for both bright and dim regions. Line fluorescence recovery after photobleaching showed that the reticulated pattern was maintained as the fluorescence recovered in the bleached areas. Cytochalasin D did not affect the staining pattern, but the pattern was eliminated by cholesterol depletion with methyl-beta-cyclodextrin. We conclude that the reticulated fluorescence pattern was caused by increased optical path lengths through the microvilli and microridges compared with the flat areas on the apical membrane.

  14. Reticulated lipid probe fluorescence reveals MDCK cell apical membrane topography.

    PubMed Central

    Colarusso, Pina; Spring, Kenneth R

    2002-01-01

    High spatial resolution confocal microscopy of young MDCK cells stained with the lipophilic probe 1,1'-dihexadecyl-3,3,3',3'- tetramethylindocarbocyanine perchlorate (DiIC(16)) revealed a reticulated fluorescence pattern on the apical membrane. DiIC(16) was delivered as crystals to live cells to minimize possible solvent perturbations of the membrane lipids. The ratio of the integrated fluorescence intensities in the bright versus dim regions was 1.6 +/- 0.1 (n = 13). Deconvolved images of the cells were consistent with exclusive plasma membrane staining. Multi-spectral and fluorescence anisotropy microscopy did not reveal differences between bright and dim regions. Bright regions coincided with microvilli and microridges observed by differential interference contrast microscopy and were stable for several minutes. Fluorescence recovery after photobleaching yielded similar diffusion coefficients (pooled D = 1.5 +/- 0.6 x 10(-9) cm(2)/s, n = 40) for both bright and dim regions. Line fluorescence recovery after photobleaching showed that the reticulated pattern was maintained as the fluorescence recovered in the bleached areas. Cytochalasin D did not affect the staining pattern, but the pattern was eliminated by cholesterol depletion with methyl-beta-cyclodextrin. We conclude that the reticulated fluorescence pattern was caused by increased optical path lengths through the microvilli and microridges compared with the flat areas on the apical membrane. PMID:11806917

  15. Apical sealing ability of metal versus plastic carrier Thermafil obturators.

    PubMed

    Clark, D S; ElDeeb, M E

    1993-01-01

    Sixty straight maxillary canines, 40 straight mandibular incisors, and 40 curved mesial canals of 27 mandibular molars were instrumented and randomly assigned to one of seven groups of 20 canals. Experimental groups were obturated with metal or plastic carrier Thermafil obturators. Control groups were obturated using the lateral condensation technique. An additional group of 20 unobturated curved molar canals served as positive controls. Kerr Pulp Canal Sealer was used in all obturation groups. The presence or absence of apical extrusion of gutta-percha was recorded. Teeth were suspended in black India ink for 2 wk, cleared, and then examined under a dissecting microscope at x20 magnification. No leakage was found in any of the obturated canals, whereas unobturated controls showed total dye penetration. Plastic carrier Thermafil and metal carrier Thermafil groups produced a significantly greater incidence of apical extrusion of gutta-percha compared with lateral condensation groups (p < 0.001). Extrusion for Thermafil groups occurred significantly more frequently in straight compared with curved canals (p = 0.002). The Thermafil groups showed a higher frequency of filled lateral and accessory canals than in the lateral condensation group; however, this was statistically insignificant (p = 0.48).

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

    PubMed Central

    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

  17. Partial triceps disruption: a case report.

    PubMed

    Foulk, David M; Galloway, Marc T

    2011-03-01

    Partial triceps tendon disruptions are a rare injury that can lead to debilitating outcomes if misdiagnosed or managed inappropriately. The clinician should have a high index of suspicion when the mechanism involves a fall onto an outstretched arm and there is resultant elbow extension weakness along with pain and swelling. The most common location of rupture is at the tendon-osseous junction. This case report illustrates a partial triceps tendon disruption with involvement of, primarily, the medial head and the superficial expansion. Physical examination displayed weakness with resisted elbow extension in a flexed position over 90°. Radiographs revealed a tiny fleck of bone proximal to the olecranon, but this drastically underestimated the extent of injury upon surgical exploration. Magnetic resonance imaging is essential to ascertain the percentage involvement of the tendon; it can be used for patient education and subsequently to determine treatment recommendations. Although excellent at finding associated pathology, it may misjudge the size of the tear. As such, physicians must consider associated comorbidities and patient characteristics when formulating treatment plans.

  18. [Giant negative T waves in idiopathic apical diverticulum of the left ventricle in adults].

    PubMed

    Barboteu, M; Desnos, M; Hagège, A; Dufour, M; Chauvaud, S; Junes, G; Baleynaud, S; Bruneval, P; Guérot, C

    1995-10-01

    Left ventricular diverticula, congenital or acquired, with normal coronary arteries are rare. Apical diverticula are exceptionally rare in the adult. The authors present the clinical, paraclinical, anatomopathological pre- and postoperative data in a case of apical diverticulum of the left ventricle presenting with giant negative T waves. The differential diagnosis of these electrocardiographic changes is discussed, in particular apical cardiomyopathy, especially as the two conditions may be associated.

  19. Intrapartum Pubic Symphysis Disruption

    PubMed Central

    Pires, RES; Labronici, PJ; Giordano, V; Kojima, KE; Kfuri, M; Barbisan, M; Wajnsztejn, A; de Andrade, MAP

    2015-01-01

    During pregnancy, high progesterone and relaxin levels produce physiological ligament relaxation on the pelvis. Therefore, moderate pubic symphysis and sacroiliac joints relaxing provide birth canal widening, thereby facilitating vaginal delivery. Sometimes, functional pain or pelvic instability may occur during pregnancy or puerperium, which is defined as symptomatic pelvic girdle relaxation. In rare cases, a pubic symphysis disruption can occur during the labor, causing severe pain and functional limitations. The early recognition of this injury is crucial to prevent complications and improve clinical and functional outcomes. This study reports an acute symphyseal disruption resulting from childbirth in a primiparous patient who underwent open reduction and internal fixation with plate and screws. After a 6 months follow-up, the patient presented no pain and satisfactory functional recovery. PMID:27057391

  20. [Xenoestrogens: endocrine disrupting compounds].

    PubMed

    Wozniak, Milena; Murias, Marek

    2008-11-01

    In recent years much attention has been paid to the issues of chemicals that disrupt the normal function of endocrine system, namely xenoestrogens. These chemicals can mimic the activity of endogenous estrogens, antagonize their interaction with estrogen receptors or disrupt the synthesis, metabolism and functions of endogenous female hormones. Due to the fact that they act thanks to many different mechanisms, it is very difficult to estimate their estrogenic activity by means of a simple tests. The important issue remains the fact that xenoestrogens may have a positive or negative influence on the function of the endocrine system. It seems to be very important that there are many sources of xenoestrogens, that is not only vegetables and fruit (phytoestrogens), but also metals (Co, Cu, Ni, Cr, Pb), dental appliances (alkilphenols), food containers or blood containers (PVC--polyvinyl chloride, DEHP--di-(2-ethylhexyl) phthalate), cosmetics (parabens) and pesticides (DDT--dichlor-diphenyl-trichlorethylane, endosulfane).

  1. [Electrical excitability of the apical dendrites of mammalian cortical pyramidal neurons].

    PubMed

    Fan, Shih-Fang

    2012-12-25

    The electrical excitability of the dendrites of the cortical neurons was first studied on the apical dendrites of the pyramidal neurons. Professor ZHANG Xiang-Tong (H-T Chang) made important contributions in the fifties of last century on this topic. Through numerous studies later on, it has been established that the electrical excitability of dendrites of different types of neurons, even different dendrites in the same neuron is different. For the apical dendrites of the cortical pyramidal neurons, neither a single nor a train of repetitive action potentials with constant frequency can reach its terminal portion. However, some of the burst repetitive responses with non-constant frequency of the apical dendrite elicited by direct current injected into the soma may reach the terminal portion. This may be due to: (1) the calcium ion concentration in the apical dendrite is increased by the burst activities, which, in turn, increases the electrical excitability of the apical dendrite and /or (2) some retrograde collaterals of axon of the activated soma reach the apical dendrite and release neurotransmitter glutamate, which changes the properties of the voltage-gated ion channels in the apical dendrite. Low electrical excitability of the apical dendrites seems to be essential for the processing of numerous income signals to the terminal portion of the apical dendrites.

  2. Conversion of proteins from a non-polarized to an apical secretory pattern in MDCK cells

    SciTech Connect

    Vogel, Lotte K. . E-mail: vogel@imbg.ku.dk; Larsen, Jakob E.; Hansen, Martin; Truffer, Renato

    2005-05-13

    Previously it was shown that fusion proteins containing the amino terminus of an apical targeted member of the serpin family fused to the corresponding carboxyl terminus of the non-polarized secreted serpin, antithrombin, are secreted mainly to the apical side of MDCK cells. The present study shows that this is neither due to the transfer of an apical sorting signal from the apically expressed proteins, since a sequence of random amino acids acts the same, nor is it due to the deletion of a conserved signal for correct targeting from the non-polarized secreted protein. Our results suggest that the polarity of secretion is determined by conformational sensitive sorting signals.

  3. Micro-CT evaluation of apical delta morphologies in human teeth

    PubMed Central

    Gao, Xianhua; Tay, Franklin R.; Gutmann, James L.; Fan, Wei; Xu, Ting; Fan, Bing

    2016-01-01

    The apical delta is an intricate system within the root canal and incompletely debridement may affect the long-term prognosis of root canal therapy. The aim of the present study is to investigate the morphologic features of apical deltas in human teeth with micro-computed tomography (micro-CT) using a centreline-fitting algorithm. One hundred and thirty-six apical deltas were detected in 1400 teeth. Molars had more apical deltas (15.8%) than anterior teeth (6.3%). In maxillary molars, the mesiobuccal root had a significantly higher prevalence of apical delta than the palatal root or the distobuccal root. The median vertical distance of the apical delta was 1.87 mm with 13% more than 3 mm. The median diameter and length of the apical delta branches were 132.3 and 934.5 μm. Apical delta branches were not straight with cross-sectional shapes being non-circular. These morphological features of apical delta may complicate debridement of the infected root canal system. PMID:27819309

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

    PubMed

    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.

  5. Conducting polyaniline nanowire electrode junction

    NASA Astrophysics Data System (ADS)

    Gaikwad, Sumedh; Bodkhe, Gajanan; Deshmukh, Megha; Patil, Harshada; Rushi, Arti; Shirsat, Mahendra D.; Koinkar, Pankaj; Kim, Yun-Hae; Mulchandani, Ashok

    2015-03-01

    In this paper, a synthesis of conducting polyaniline nanowires electrode junction (CPNEJ) has been reported. Conducting polyaniline nanowires electrode junction on Si/SiO2 substrate (having 3 μm gap between two gold microelectrodes) is prepared. Polyaniline nanowires with diameter (ca. 140 nm to 160 nm) were synthesized by one step electrochemical polymerization using galvanostatic (constant current) technique to bridge this gap. The surface morphology of CPNEJ was studied by scanning electron microscope (SEM). The synthesized CPNEJ is an excellent platform for biosensor applications.

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

    PubMed

    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.

  7. Simple Electronic Analog of a Josephson Junction.

    ERIC Educational Resources Information Center

    Henry, R. W.; And Others

    1981-01-01

    Demonstrates that an electronic Josephson junction analog constructed from three integrated circuits plus an external reference oscillator can exhibit many of the circuit phenomena of a real Josephson junction. Includes computer and other applications of the analog. (Author/SK)

  8. Growth and development of the root apical meristem.

    PubMed

    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.

  9. Oral microbiota species in acute apical endodontic abscesses

    PubMed Central

    George, Noelle; Flamiatos, Erin; Kawasaki, Kellie; Kim, Namgu; Carriere, Charles; Phan, Brian; Joseph, Raphael; Strauss, Shay; Kohli, Richie; Choi, Dongseok; Craig Baumgartner, J.; Sedgley, Christine; Maier, Tom; Machida, Curtis A.

    2016-01-01

    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 were not commonly

  10. F-actin binding protein, anillin, regulates integrity of intercellular junctions in human epithelial cells

    PubMed Central

    Feygin, Alex; Ivanov, Andrei I.

    2015-01-01

    Tight junctions (TJ) and adherens junctions (AJ) are key morphological features of differentiated epithelial cells that regulate the integrity and permeability of tissue barriers. Structure and remodeling of epithelial junctions depends on their association with the underlying actomyosin cytoskeleton. Anillin is a unique scaffolding protein interacting with different cytoskeletal components, including actin filaments and myosin motors. Its role in the regulation of mammalian epithelial junctions remains unexplored. Downregulation of anillin expression in human prostate, colonic, and lung epithelial cells triggered AJ and TJ disassembly without altering the expression of junctional proteins. This junctional disassembly was accompanied by dramatic disorganization of the perijunctional actomyosin belt; while the general architecture of the actin cytoskeleton, and activation status of non-muscle myosin II, remained unchanged. Furthermore, loss of anillin disrupted the adducin-spectrin membrane skeleton at the areas of cell-cell contact, selectively decreased γ-adducin expression, and induced cytoplasmic aggregation of αII-spectrin. Anillin knockdown activated c-Jun N-terminal kinase (JNK), and JNK inhibition restored AJ and TJ integrity and cytoskeletal organization in anillin-depleted cells. These findings suggest a novel role for anillin in regulating intercellular adhesion in model human epithelia by mechanisms involving the suppression of JNK activity and controlling the assembly of the perijunctional cytoskeleton. PMID:25809162

  11. Hepatic immunohistochemical localization of the tight junction protein ZO-1 in rat models of cholestasis.

    PubMed Central

    Anderson, J. M.; Glade, J. L.; Stevenson, B. R.; Boyer, J. L.; Mooseker, M. S.

    1989-01-01

    Structural alterations in hepatocyte tight junctions accompanying cholestasis were investigated using immunolocalization of ZO-1, the first known protein component of the tight junction. Disruption in the paracellular barrier function of the tight junction has been proposed to allow reflux of bile into the blood. Cholestasis was induced in 210 to 235 g male Sprague-Dawley rats either by five consecutive daily subcutaneous injections of 17-alpha-ethinyl estradiol (0.5 mg/kg/d in propylene glycol) or ligation of the common bile duct for 72 hours. The structural organization of the tight junction was assessed in each model by indirect immunofluorescent and immunoperoxidase staining for ZO-1 on frozen sections of liver and compared with controls. In control, sham-operated, and estradiol-injected animals, ZO-1 localizes in a uniform continuous manner along the margins of the canaliculi. In contrast, bile duct ligation results in the appearance of numerous discontinuities in ZO-1 staining accompanied by dilation or collapse of the lumenal space. Tissue content of the ZO-1 protein, as determined by quantitative immunoblotting, was unaffected in either cholestatic model compared with controls. These findings indicate that the molecular organization of the tight junction can be assessed from immunostaining patterns of ZO-1 in frozen sections of cholestatic livers. Under these experimental conditions, the organization of the tight junction at the level of the ZO-1 protein is altered by bile duct obstruction but not by ethinyl estradiol. Images Figure 1 Figure 2 PMID:2719075

  12. Inhibition of connexin43 gap junction channels by the endocrine disruptor ioxynil

    SciTech Connect

    Leithe, Edward; Kjenseth, Ane; Bruun, Jarle; Sirnes, Solveig; Rivedal, Edgar

    2010-08-15

    Gap junctions are intercellular plasma membrane domains containing channels that mediate transport of ions, metabolites and small signaling molecules between adjacent cells. Gap junctions play important roles in a variety of cellular processes, including regulation of cell growth and differentiation, maintenance of tissue homeostasis and embryogenesis. The constituents of gap junction channels are a family of trans-membrane proteins called connexins, of which the best-studied is connexin43. Connexin43 functions as a tumor suppressor protein in various tissue types and is frequently dysregulated in human cancers. The pesticide ioxynil has previously been shown to act as an endocrine disrupting chemical and has multiple effects on the thyroid axis. Furthermore, both ioxynil and its derivative ioxynil octanoate have been reported to induce tumors in animal bioassays. However, the molecular mechanisms underlying the possible tumorigenic effects of these compounds are unknown. In the present study we show that ioxynil and ioxynil octanoate are strong inhibitors of connexin43 gap junction channels. Both compounds induced rapid loss of connexin43 gap junctions at the plasma membrane and increased connexin43 degradation. Ioxynil octanoate, but not ioxynil, was found to be a strong activator of ERK1/2. The compounds also had different effects on the phosphorylation status of connexin43. Taken together, the data show that ioxynil and ioxynil octanoate are potent inhibitors of intercellular communication via gap junctions.

  13. Exploring tight junction alteration using double fluorescent probe combination of lanthanide complex with gold nanoclusters

    NASA Astrophysics Data System (ADS)

    Wang, Xinyi; Wang, Na; Yuan, Lan; Li, Na; Wang, Junxia; Yang, Xiaoda

    2016-08-01

    Tight junctions play a key role in restricting or regulating passage of liquids, ions and large solutes through various biological barriers by the paracellular route. Changes in paracellular permeation indicate alteration of the tight junction. However, it is very difficult to obtain the structural change information by measuring paracellular flux based on transepithelial electrical resistance or using fluorescein-labeled dextrans. Here we show that the BSA and GSH stabilized gold nanoclusters exhibit marginal cytotoxicity and pass through the MDCK monolayer exclusively through the paracellular pathway. We propose a double fluorescence probe strategy, the combination of a proven paracellular indicator (europium complex) with fluorescent gold nanoclusters. We calculate changes of structural parameters in tight junctions based on determination of the diffusion coefficients of the probes. Two different types of tight junction openers are used to validate our strategy. Results show that EDTA disrupts tight junction structures and induces large and smooth paracellular pore paths with an average radius of 17 nm, but vanadyl complexes induce paths with the radius of 6 nm. The work suggests that the double fluorescence probe strategy is a useful and convenient approach for in vitro investigation of tight junction structural alternations caused by pharmacological or pathological events.

  14. Exploring tight junction alteration using double fluorescent probe combination of lanthanide complex with gold nanoclusters

    PubMed Central

    Wang, Xinyi; Wang, Na; Yuan, Lan; Li, Na; Wang, Junxia; Yang, Xiaoda

    2016-01-01

    Tight junctions play a key role in restricting or regulating passage of liquids, ions and large solutes through various biological barriers by the paracellular route. Changes in paracellular permeation indicate alteration of the tight junction. However, it is very difficult to obtain the structural change information by measuring paracellular flux based on transepithelial electrical resistance or using fluorescein-labeled dextrans. Here we show that the BSA and GSH stabilized gold nanoclusters exhibit marginal cytotoxicity and pass through the MDCK monolayer exclusively through the paracellular pathway. We propose a double fluorescence probe strategy, the combination of a proven paracellular indicator (europium complex) with fluorescent gold nanoclusters. We calculate changes of structural parameters in tight junctions based on determination of the diffusion coefficients of the probes. Two different types of tight junction openers are used to validate our strategy. Results show that EDTA disrupts tight junction structures and induces large and smooth paracellular pore paths with an average radius of 17 nm, but vanadyl complexes induce paths with the radius of 6 nm. The work suggests that the double fluorescence probe strategy is a useful and convenient approach for in vitro investigation of tight junction structural alternations caused by pharmacological or pathological events. PMID:27574102

  15. The Yolla Bolly junction revisited

    SciTech Connect

    Blake, M.C.; Jayko, A.S. ); Jones, D.L. . Dept. of Geology and Geophysics); Engebretson, D.C. . Dept. of Geology)

    1993-04-01

    West of Red Bluff, California, rocks of the northern Coast Ranges, Klamath-Sierra Nevada, and Great Valley provinces come together at what has been called the Yolla Bolly junction. Mapping of the Red Bluff and Willows 1:100,000 quadrangles has greatly clarified the enigmatic features of this complex area. Terranes of the Klamath Mountains and their Cretaceous sedimentary cover have been thrust northwestward over the Elder Creek terrane and Franciscan rocks, north of the left-lateral Cold Fork fault zone. The Condrey Mountain window (Franciscan Pickett Peak terrane) provides a measure of the magnitude of this thrusting (ca 90 km). South of the Cold Fork fault zone, the Franciscan and Elder Creek terranes were driven southeastward as tectonic wedges onto Sierran-Klamath basement. Timing of this scissor-tectonics is not constrained near the junction, but further north in southwest Oregon, Lower Eocene strata were deformed by overthrusting of the Klamath block whereas Upper Eocene strata overlap the thrust, indicating that thrusting occurred between about 52 and 60 Ma. Plate reconstructions for this time interval indicate the close proximity of the Kula-Farallon-North America triple junction and that old (ca 100 m.y.) Farallon lithosphere was being subducted north of the junction whereas to the south, very young (ca 10 m.y.) Kula plate was presumably obducted onto North America.

  16. Manuel's asteroid disruption technique.

    PubMed

    John, Manuel; Ipe, Abraham; Jacob, Ivan

    2015-06-01

    A seventy-year-old male presented with dense asteroid hyalosis in both eyes. He had undergone cataract extraction in one eye 3 years ago, and the other eye had immature cataract. Both the autorefractor and dilated streak retinoscopy did not give readings and subjective visual improvement could not be achieved. Immediately following YAG posterior capsulotomy and anterior vitreous asteroid disruption, the vision improved to 20/20 with recordable auto refractor and streak retinoscopy values. Our initial experience indicates that the treatment is simple, safe and effective but needs controlled and prospective studies to confirm its long-term safety.

  17. Nectin-2 and N-cadherin interact through extracellular domains and induce apical accumulation of F-actin in apical constriction of Xenopus neural tube morphogenesis.

    PubMed

    Morita, Hitoshi; Nandadasa, Sumeda; Yamamoto, Takamasa S; Terasaka-Iioka, Chie; Wylie, Christopher; Ueno, Naoto

    2010-04-01

    Neural tube formation is one of the most dynamic morphogenetic processes of vertebrate development. However, the molecules regulating its initiation are mostly unknown. Here, we demonstrated that nectin-2, an immunoglobulin-like cell adhesion molecule, is involved in the neurulation of Xenopus embryos in cooperation with N-cadherin. First, we found that, at the beginning of neurulation, nectin-2 was strongly expressed in the superficial cells of neuroepithelium. The knockdown of nectin-2 impaired neural fold formation by attenuating F-actin accumulation and apical constriction, a cell-shape change that is required for neural tube folding. Conversely, the overexpression of nectin-2 in non-neural ectoderm induced ectopic apical constrictions with accumulated F-actin. However, experiments with domain-deleted nectin-2 revealed that the intracellular afadin-binding motif, which links nectin-2 and F-actin, was not required for the generation of the ectopic apical constriction. Furthermore, we found that nectin-2 physically interacts with N-cadherin through extracellular domains, and they cooperatively enhanced apical constriction by driving the accumulation of F-actin at the apical cell surface. Interestingly, the accumulation of N-cadherin at the apical surface of neuroepithelium was dependent on the presence of nectin-2, but that of nectin-2 was not affected by depletion of N-cadherin. We propose a novel mechanism of neural tube morphogenesis regulated by the two types of cell adhesion molecules.

  18. To determine whether the first file to bind at the working length corresponds to the apical diameter in roots with apical curvatures both before and after preflaring

    PubMed Central

    Dillon, Jaidev Singh; Amita; Gill, Bobbin

    2012-01-01

    Aim: To evaluate the discrepancies between the diameter of the canal and the first file to bind at the working length, before and after preflaring in teeth with apical curvatures. Materials and Methods: Twenty teeth with apical curvatures were selected for the study. Following access, the patency file was fixed at the working length, and the apices were ground perpendicular to the canal at this level. Diameters of canal and the first file to bind at the working length were observed for each tooth, both before and after preflaring, under stereomicroscope at 30X magnification. Results: ANOVA and post hoc Bonferroni tests showed significant differences in both groups regarding anatomical diameter at working length and the first file to bind. The area of contact of the file at apical region remained the same in both groups. Conclusion: Using the first file to bind for gauging the diameter of the apical canal was found to be an unreliable method in teeth with apical curvatures, even after preflaring. PMID:23112485

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

    PubMed

    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.

  20. Does apical negative pressure prevent the apical extrusion of debris and irrigant compared with conventional irrigation? A systematic review and meta-analysis.

    PubMed

    Romualdo, Priscilla Coutinho; de Oliveira, Katharina Morant Holanda; Nemezio, Mariana Alencar; Küchler, Erika Calvano; Silva, Raquel Assed Bezerra; Nelson-Filho, Paulo; Silva, Lea Assed Bezerra

    2017-02-02

    The aim of this study was to evaluate if apical negative pressure (ANP) irrigation prevents the apical extrusion of debris and irrigant compared with conventional needle irrigation through a systematic review and meta-analysis. A computer search of dental literature was performed using four different databases. A combination of the terms 'apical negative pressure', 'endovac', 'apical extrusion', 'extrusion' and 'endodontics' was used. Studies that used extracted human teeth with a mature apex and that evaluated the apical extrusion of debris and/or irrigating solution were included. After an evaluation of the full studies according to the eligibility criteria, eight studies were critically analysed and subjected to quality assessment and risk of bias. Only four studies that evaluated extrusion of irrigant were considered as having high methodological quality and were subjected to a meta-analysis. Studies evaluating extrusion of debris did not have sufficient methodological quality to be subjected to the meta-analysis. The forest plot indicated that ANP irrigation prevents the risk of irrigant extrusion compared with conventional irrigation (OR 0.07 [95%CI 0.02-0.20]; P < 0.00001). This systematic review and meta-analysis showed that ANP prevents the apical extrusion of irrigant. There is no evidence if this type of irrigation prevents the extrusion of debris.

  1. 27 CFR 9.164 - River Junction.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false River Junction. 9.164... River Junction. (a) Name. The name of the viticultural area described in this section is “River Junction.” (b) Approved maps. The appropriate maps for determining the boundaries of the River...

  2. 27 CFR 9.164 - River Junction.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false River Junction. 9.164... River Junction. (a) Name. The name of the viticultural area described in this section is “River Junction.” (b) Approved maps. The appropriate maps for determining the boundaries of the River...

  3. Arabidopsis FIM5 decorates apical actin filaments and regulates their organization in the pollen tube

    PubMed Central

    Zhang, Meng; Zhang, Ruihui; Qu, Xiaolu; Huang, Shanjin

    2016-01-01

    The actin cytoskeleton is increasingly recognized as a major regulator of pollen tube growth. Actin filaments have distinct distribution patterns and dynamic properties within different regions of the pollen tube. Apical actin filaments are highly dynamic and crucial for pollen tube growth. However, how apical actin filaments are generated and properly constructed remains an open question. Here we showed that Arabidopsis fimbrin5 (FIM5) decorates filamentous structures throughout the entire tube but is apically concentrated. Apical actin structures are disorganized to different degrees in the pollen tubes of fim5 loss-of-function mutants. Further observations suggest that apical actin structures are not constructed properly because apical actin filaments cannot be maintained at the cortex of fim5 pollen tubes. Actin filaments appeared to be more curved in fim5 pollen tubes and this was confirmed by measurements showing that the convolutedness and the rate of change of convolutedness of actin filaments was significantly increased in fim5 pollen tubes. This suggests that the rigidity of the actin filaments may be compromised in fim5 pollen tubes. Further, the apical cell wall composition is altered, implying that tip-directed vesicle trafficking events are impaired in fim5 pollen tubes. Thus, we found that FIM5 decorates apical actin filaments and regulates their organization in order to drive polarized pollen tube growth. PMID:27117336

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

    PubMed

    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.

  5. PTEN-mediated segregation of phosphoinositides at the apical membrane controls epithelial morphogenesis through Cdc42

    PubMed Central

    Martin-Belmonte, Fernando; Gassama, Ama; Datta, Anirban; Yu, Wei; Rescher±, Ursula; Gerke±, Volker; Mostov, Keith

    2007-01-01

    Summary Formation of the apical surface and lumen is a fundamental, yet poorly understood, step in epithelial organ development. We show that PTEN localizes to the apical plasma membrane during epithelial morphogenesis to mediate the enrichment of PtdIns(4,5)P2 at this domain during cyst development in three dimensional culture. Ectopic PtdIns(4,5)P2 at the basolateral surface causes apical proteins to relocalize to the basolateral surface. Annexin 2 (Ax2) binds PtdIns(4,5)P2 and is recruited to the apical surface. Ax2 binds Cdc42, recruiting it to the apical surface. Cdc42 recruits aPKC to the apical surface. Loss of function of PTEN, Ax2, Cdc42 or aPKC prevents normal development of the apical surface and lumen. We conclude that the mechanism of PTEN, PtdIns(4,5)P2, Ax2, Cdc42 and aPKC controls apical plasma membrane and lumen formation. PMID:17254974

  6. Cell-Cell Adhesions and Cell Contractility Are Upregulated upon Desmosome Disruption

    PubMed Central

    Sumigray, Kaelyn; Zhou, Kang; Lechler, Terry

    2014-01-01

    Desmosomes are perturbed in a number of disease states – including genetic disorders, autoimmune and bacterial diseases. Here, we report unexpected changes in other cell-cell adhesion structures upon loss of desmosome function. We found that perturbation of desmosomes by either loss of the core desmosomal protein desmoplakin or treatment with pathogenic anti-desmoglein 3 (Dsg3) antibodies resulted in changes in adherens junctions consistent with increased tension. The total amount of myosin IIA was increased in desmoplakin-null epidermis, and myosin IIA became highly localized to cell contacts in both desmoplakin-null and anti-Dsg3-treated mouse keratinocytes. Inhibition of myosin II activity reversed the changes to adherens junctions seen upon desmosome disruption. The increased cortical myosin IIA promoted epithelial sheet fragility, as myosin IIA-null cells were less susceptible to disruption by anti-Dsg3 antibodies. In addition to the changes in adherens junctions, we found a significant increase in the expression of a number of claudin genes, which encode for transmembrane components of the tight junction that provide barrier function. These data demonstrate that desmosome disruption results in extensive transcriptional and posttranslational changes that alter the activity of other cell adhesion structures. PMID:25006807

  7. Bacterial induction of Snail1 contributes to blood-brain barrier disruption

    PubMed Central

    Kim, Brandon J.; Hancock, Bryan M.; Bermudez, Andres; Cid, Natasha Del; Reyes, Efren; van Sorge, Nina M.; Lauth, Xavier; Smurthwaite, Cameron A.; Hilton, Brett J.; Stotland, Aleksandr; Banerjee, Anirban; Buchanan, John; Wolkowicz, Roland; Traver, David; Doran, Kelly S.

    2015-01-01

    Bacterial meningitis is a serious infection of the CNS that results when blood-borne bacteria are able to cross the blood-brain barrier (BBB). Group B Streptococcus (GBS) is the leading cause of neonatal meningitis; however, the molecular mechanisms that regulate bacterial BBB disruption and penetration are not well understood. Here, we found that infection of human brain microvascular endothelial cells (hBMECs) with GBS and other meningeal pathogens results in the induction of host transcriptional repressor Snail1, which impedes expression of tight junction genes. Moreover, GBS infection also induced Snail1 expression in murine and zebrafish models. Tight junction components ZO-1, claudin 5, and occludin were decreased at both the transcript and protein levels in hBMECs following GBS infection, and this repression was dependent on Snail1 induction. Bacteria-independent Snail1 expression was sufficient to facilitate tight junction disruption, promoting BBB permeability to allow bacterial passage. GBS induction of Snail1 expression was dependent on the ERK1/2/MAPK signaling cascade and bacterial cell wall components. Finally, overexpression of a dominant-negative Snail1 homolog in zebrafish elevated transcription of tight junction protein–encoding genes and increased zebrafish survival in response to GBS challenge. Taken together, our data support a Snail1-dependent mechanism of BBB disruption and penetration by meningeal pathogens. PMID:25961453

  8. Cell-cell adhesions and cell contractility are upregulated upon desmosome disruption.

    PubMed

    Sumigray, Kaelyn; Zhou, Kang; Lechler, Terry

    2014-01-01

    Desmosomes are perturbed in a number of disease states - including genetic disorders, autoimmune and bacterial diseases. Here, we report unexpected changes in other cell-cell adhesion structures upon loss of desmosome function. We found that perturbation of desmosomes by either loss of the core desmosomal protein desmoplakin or treatment with pathogenic anti-desmoglein 3 (Dsg3) antibodies resulted in changes in adherens junctions consistent with increased tension. The total amount of myosin IIA was increased in desmoplakin-null epidermis, and myosin IIA became highly localized to cell contacts in both desmoplakin-null and anti-Dsg3-treated mouse keratinocytes. Inhibition of myosin II activity reversed the changes to adherens junctions seen upon desmosome disruption. The increased cortical myosin IIA promoted epithelial sheet fragility, as myosin IIA-null cells were less susceptible to disruption by anti-Dsg3 antibodies. In addition to the changes in adherens junctions, we found a significant increase in the expression of a number of claudin genes, which encode for transmembrane components of the tight junction that provide barrier function. These data demonstrate that desmosome disruption results in extensive transcriptional and posttranslational changes that alter the activity of other cell adhesion structures.

  9. Relativistic tidal disruption events

    NASA Astrophysics Data System (ADS)

    Levan, A.

    2012-12-01

    In March 2011 Swift detected an extremely luminous and long-lived outburst from the nucleus of an otherwise quiescent, low luminosity (LMC-like) galaxy. Named Swift J1644+57, its combination of high-energy luminosity (1048 ergs s-1 at peak), rapid X-ray variability (factors of >100 on timescales of 100 seconds) and luminous, rising radio emission suggested that we were witnessing the birth of a moderately relativistic jet (Γ ˜ 2 - 5), created when a star is tidally disrupted by the supermassive black hole in the centre of the galaxy. A second event, Swift J2058+0516, detected two months later, with broadly similar properties lends further weight to this interpretation. Taken together this suggests that a fraction of tidal disruption events do indeed create relativistic outflows, demonstrates their detectability, and also implies that low mass galaxies can host massive black holes. Here, I briefly outline the observational properties of these relativistic tidal flares observed last year, and their evolution over the first year since their discovery.

  10. Cytoskeletal Components of an Invasion Machine—The Apical Complex of Toxoplasma gondii

    PubMed Central

    Hu, Ke; Johnson, Jeff; Florens, Laurence; Fraunholz, Martin; Suravajjala, Sapna; DiLullo, Camille; Yates, John; Roos, David S; Murray, John M

    2006-01-01

    The apical complex of Toxoplasma gondii is widely believed to serve essential functions in both invasion of its host cells (including human cells), and in replication of the parasite. The understanding of apical complex function, the basis for its novel structure, and the mechanism for its motility are greatly impeded by lack of knowledge of its molecular composition. We have partially purified the conoid/apical complex, identified ~200 proteins that represent 70% of its cytoskeletal protein components, characterized seven novel proteins, and determined the sequence of recruitment of five of these proteins into the cytoskeleton during cell division. Our results provide new markers for the different subcompartments within the apical complex, and revealed previously unknown cellular compartments, which facilitate our understanding of how the invasion machinery is built. Surprisingly, the extreme apical and extreme basal structures of this highly polarized cell originate in the same location and at the same time very early during parasite replication. PMID:16518471

  11. Sharp curvature of premolar resulting in external apical root resorption of the neighbouring molar.

    PubMed

    Ulusoy, Ozgür İlke Atasoy

    2011-01-01

    This case report describes an external apical root resorption resulted from the unusual root morphology of the neighbouring tooth. A 28-year-old female was referred to the department of endodontics with a complaint of intense pain in her maxillary second premolar tooth. The clinical and radiographical evaluation revealed an external apical resorption in the mesial root of the maxillary first molar, which shows close proximity to the severely curved root of the premolar. A successful root canal treatment of the premolar was performed using anticurvature filing method. However, molar tooth received no curative treatment. One-year followup of the apical external resorption did not show any progression. External apical root resorption affecting single permanent tooth may be induced from the pressure exerted during the eruption of the adjacent tooth with unusual root morphology. The preferred approach for the management of such apical resorption cases includes long-term observation and no curative treatment.

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

    PubMed

    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.

  13. Tight Junction Proteins in Human Schwann Cell Autotypic Junctions

    PubMed Central

    Alanne, Maria H.; Pummi, Kati; Heape, Anthony M.; Grènman, Reidar; Peltonen, Juha; Peltonen, Sirkku

    2009-01-01

    Tight junctions (TJs) form physical barriers in various tissues and regulate paracellular transport of ions, water, and molecules. Myelinating Schwann cells form highly organized structures, including compact myelin, nodes of Ranvier, paranodal regions, Schmidt-Lanterman incisures, periaxonal cytoplasmic collars, and mesaxons. Autotypic TJs are formed in non-compacted myelin compartments between adjacent membrane lamellae of the same Schwann cell. Using indirect immunofluorescence and RT-PCR, we analyzed the expression of adherens junction (E-cadherin) and TJ [claudins, zonula occludens (ZO)-1, occludin] components in human peripheral nerve endoneurium, showing clear differences with published rodent profiles. Adult nerve paranodal regions contained E-cadherin, claudin-1, claudin-2, and ZO-1. Schmidt-Lanterman incisures contained E-cadherin, claudin-1, claudin-2, claudin-3, claudin-5, ZO-1, and occludin. Mesaxons contained E-cadherin, claudin-1, claudin-2, claudin-3, ZO-1, and occludin. None of the proteins studied were associated with nodal inter-Schwann cell junctions. Fetal nerve expression of claudin-1, claudin-3, ZO-1, and occludin was predominantly punctate, with a mesaxonal labeling pattern, but paranodal (ZO-1, claudin-3) and Schmidt-Lanterman incisure (claudins-1 and -3) expression profiles typical of compact myelin were visible by gestational week 37. The clear differences observed between human and published rodent nerve profiles emphasize the importance of human studies when translating the results of animal models to human diseases. (J Histochem Cytochem 57:523–529, 2009) PMID:19153196

  14. Death and Transfiguration of a Triple Junction in the South Atlantic

    PubMed

    Ligi; Bonatti; Bortoluzzi; Carrara; Fabretti; Penitenti; Gilod; Peyve; Skolotnev; Turko

    1997-04-11

    Three major lithospheric plates-Antarctic, South American, and African-meet in the South Atlantic near Bouvet Island where the Mid-Atlantic Ridge (MAR), the Southwest Indian Ridge (SWIR), and the American Antarctic Ridge converge toward a fast evolving triple junction. A major magmatic pulse has recently built a new, swollen segment of the SWIR (Spiess Ridge) that is propagating toward the MAR at a rate of 4 to 5 centimeters per year, disrupting a former ridge-ridge-ridge (RRR) triple junction. A new triple junction will be established about 70 kilometers to the north when the propagating SWIR/Spiess segment will impact with the MAR, probably within the next 1 million years. The American Antarctic Ridge will take advantage of the MAR/SWIR duel by capturing an approximately 70-kilometer stretch of MAR, whereas the Antarctic plate will increase its size.

  15. Cell disruption for microalgae biorefineries.

    PubMed

    Günerken, E; D'Hondt, E; Eppink, M H M; Garcia-Gonzalez, L; Elst, K; Wijffels, R H

    2015-01-01

    Microalgae are a potential source for various valuable chemicals for commercial applications ranging from nutraceuticals to fuels. Objective in a biorefinery is to utilize biomass ingredients efficiently similarly to petroleum refineries in which oil is fractionated in fuels and a variety of products with higher value. Downstream processes in microalgae biorefineries consist of different steps whereof cell disruption is the most crucial part. To maintain the functionality of algae biochemicals during cell disruption while obtaining high disruption yields is an important challenge. Despite this need, studies on mild disruption of microalgae cells are limited. This review article focuses on the evaluation of conventional and emerging cell disruption technologies, and a comparison thereof with respect to their potential for the future microalgae biorefineries. The discussed techniques are bead milling, high pressure homogenization, high speed homogenization, ultrasonication, microwave treatment, pulsed electric field treatment, non-mechanical cell disruption and some emerging technologies.

  16. PLEKHA7 modulates epithelial tight junction barrier function

    PubMed Central

    Paschoud, Serge; Jond, Lionel; Guerrera, Diego; Citi, Sandra

    2014-01-01

    PLEKHA7 is a recently identified protein of the epithelial zonula adhaerens (ZA), and is part of a protein complex that stabilizes the ZA, by linking it to microtubules. Since the ZA is important in the assembly and disassembly of tight junctions (TJ), we asked whether PLEKHA7 is involved in modulating epithelial TJ barrier function. We generated clonal MDCK cell lines in which one of four different constructs of PLEKHA7 was inducibly expressed. All constructs were localized at junctions, but constructs lacking the C-terminal region were also distributed diffusely in the cytoplasm. Inducible expression of PLEKHA7 constructs did not affect the expression and localization of TJ proteins, the steady-state value of transepithelial resistance (TER), the development of TER during the calcium switch, and the flux of large molecules across confluent monolayers. In contrast, expression of three out of four constructs resulted both in enhanced recruitment of E-cadherin and associated proteins at the apical ZA and at lateral puncta adherentia (PA), a decreased TER at 18 h after assembly at normal calcium, and an attenuation in the fall in TER after extracellular calcium removal. This latter effect was inhibited when cells were treated with nocodazole. Immunoprecipitation analysis showed that PLEKHA7 forms a complex with the cytoplasmic TJ proteins ZO-1 and cingulin, and this association does not depend on the integrity of microtubules. These results suggest that PLEKHA7 modulates the dynamics of assembly and disassembly of the TJ barrier, through E-cadherin protein complex- and microtubule-dependent mechanisms. PMID:24843844

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

    PubMed Central

    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

  18. Endocrine disrupters as obesogens

    PubMed Central

    Grün, Felix; Blumberg, Bruce

    2009-01-01

    The recent dramatic rise in obesity rates is an alarming global health trend that consumes an ever increasing portion of health care budgets in Western countries. The root cause of obesity is thought to be a prolonged positive energy balance. Hence, the major focus of preventative programs for obesity has been to target overeating and inadequate physical exercise. Recent research implicates environmental risk factors, including nutrient quality, stress, fetal environment and pharmaceutical or chemical exposure as relevant contributing influences. Evidence points to endocrine disrupting chemicals that interfere with the body's adipose tissue biology, endocrine hormone systems or central hypothalamic-pituitary-adrenal axis as suspects in derailing the homeostatic mechanisms important to weight control. This review highlights recent advances in our understanding of the molecular targets and mechanisms of action for these compounds and areas of future research needed to evaluate the significance of their contribution to obesity. PMID:19433244

  19. Seebeck effect in molecular junctions.

    PubMed

    Zimbovskaya, Natalya A

    2016-05-11

    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.

  20. Seebeck effect in molecular junctions

    NASA Astrophysics Data System (ADS)

    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.

  1. Thermocouple, multiple junction reference oven

    NASA Technical Reports Server (NTRS)

    Leblanc, L. P. (Inventor)

    1981-01-01

    An improved oven for maintaining the junctions of a plurality of reference thermocouples at a common and constant temperature is described. The oven is characterized by a cylindrical body defining a heat sink with axially extended-cylindrical cavity a singularized heating element which comprises a unitary cylindrical heating element consisting of a resistance heating coil wound about the surface of metallic spool with an axial bore defined and seated in the cavity. Other features of the oven include an annular array of radially extended bores defined in the cylindrical body and a plurality of reference thermocouple junctions seated in the bores in uniformly spaced relation with the heating element, and a temperature sensing device seated in the axial bore for detecting temperature changes as they occur in the spool and circuit to apply a voltage across the coil in response to detected drops in temperatures of the spool.

  2. Molecular Insights into the Interaction between Plasmodium falciparum Apical Membrane Antigen 1 and an Invasion-Inhibitory Peptide

    PubMed Central

    Wang, Geqing; MacRaild, Christopher A.; Mohanty, Biswaranjan; Mobli, Mehdi; Cowieson, Nathan P.; Anders, Robin F.; Simpson, Jamie S.; McGowan, Sheena; Norton, Raymond S.; Scanlon, Martin J.

    2014-01-01

    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. PMID:25343578

  3. Neuromuscular junction defects in mice with mutation of dynein heavy chain 1.

    PubMed

    Courchesne, Stephanie L; Pazyra-Murphy, Maria F; Lee, Daniel J; Segal, Rosalind A

    2011-02-04

    Disruptions in axonal transport have been implicated in a wide range of neurodegenerative diseases. Cramping 1 (Cra1/+) and Legs at odd angles (Loa/+) mice, with hypomorphic mutations in the dynein heavy chain 1 gene, which encodes the ATPase of the retrograde motor protein dynein, were originally reported to exhibit late onset motor neuron disease. Subsequent, conflicting reports suggested that sensory neuron disease without motor neuron loss underlies the phenotypes of Cra1/+ and Loa/+ mice. Here, we present behavioral and anatomical analyses of Cra1/+ mice. We demonstrate that Cra1/+ mice exhibit early onset, stable behavioral deficits, including abnormal hindlimb posturing and decreased grip strength. These deficits do not progress through 24 months of age. No significant loss of primary motor neurons or dorsal root ganglia sensory neurons was observed at ages where the mice exhibited clear symptomatology. Instead, there is a decrease in complexity of neuromuscular junctions. These results indicate that disruption of dynein function in Cra1/+ mice results in abnormal morphology of neuromuscular junctions. The time course of behavioral deficits, as well as the nature of the morphological defects in neuromuscular junctions, suggests that disruption of dynein function in Cra1/+ mice causes a developmental defect in synapse assembly or stabilization.

  4. Neuromuscular Junction Defects in Mice with Mutation of dynein heavy chain 1

    PubMed Central

    Lee, Daniel J.; Segal, Rosalind A.

    2011-01-01

    Disruptions in axonal transport have been implicated in a wide range of neurodegenerative diseases. Cramping 1 (Cra1/+) and Legs at odd angles (Loa/+) mice, with hypomorphic mutations in the dynein heavy chain 1 gene, which encodes the ATPase of the retrograde motor protein dynein, were originally reported to exhibit late onset motor neuron disease. Subsequent, conflicting reports suggested that sensory neuron disease without motor neuron loss underlies the phenotypes of Cra1/+ and Loa/+ mice. Here, we present behavioral and anatomical analyses of Cra1/+ mice. We demonstrate that Cra1/+ mice exhibit early onset, stable behavioral deficits, including abnormal hindlimb posturing and decreased grip strength. These deficits do not progress through 24 months of age. No significant loss of primary motor neurons or dorsal root ganglia sensory neurons was observed at ages where the mice exhibited clear symptomatology. Instead, there is a decrease in complexity of neuromuscular junctions. These results indicate that disruption of dynein function in Cra1/+ mice results in abnormal morphology of neuromuscular junctions. The time course of behavioral deficits, as well as the nature of the morphological defects in neuromuscular junctions, suggests that disruption of dynein function in Cra1/+ mice causes a developmental defect in synapse assembly or stabilization. PMID:21346813

  5. Papillary Height and its Relation with Interproximal Distances and Cementoenamel Junction in Subjects with Chronic Periodontitis. A Cross-Sectional Study

    PubMed Central

    Narula, Satish Chander; Sharma, Rajender Kumar; Tewari, Shikha

    2016-01-01

    Introduction Presence of intact interdental papilla is considered as an essential component of aesthetic dentistry. Loss or absence of interdental papilla creates black triangles which are unpleasing. Aim The purpose of the present study was to determine relation of interproximal distances and cementoenamel junction with the classification of interdental papilla recession after surgical exposure in chronic periodontitis patients. Materials and Methods This cross-sectional, single masked study group involved 198 interdental papillae in 50 chronic periodontitis patients subjected to open flap debridement. The subjects were divided into three groups according to loss of height of interdental papillae: Class I papilla, Class II papilla, Class III papilla. The interproximal distances included vertical and horizontal distance. The vertical distance was measured from apical point of the contact area to alveolar crest; horizontal distance was measured between roots at the alveolar crest. Distance from mid buccal cementoenamel junction to apical point of the contact area was also measured. Results The vertical distance was found to be significantly affecting all the classes of loss of papillary height (p<0.05). Significantly positive correlation was found between vertical distance and buccal cementoenamel junction (p<0.05). On applying multiple linear regressions vertical distance was found to be strongest determinant of loss of papillary height. Conclusion Although interproximal distances and cementoenamel junction affect the height of interdental papilla, other factors influencing the existence of interdental papilla should also be taken into consideration for treatment planning to achieve better aesthetics. PMID:27190952

  6. Thermoelectric efficiency of molecular junctions.

    PubMed

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

    2016-09-21

    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.

  7. Squeezed States in Josephson Junctions.

    NASA Astrophysics Data System (ADS)

    Hu, X.; Nori, F.

    1996-03-01

    We have studied quantum fluctuation properties of Josephson junctions in the limit of large Josephson coupling energy and small charging energy, when the eigenstates of the system can be treated as being nearly localized. We have considered(X. Hu and F. Nori, preprints.) a Josephson junction in a variety of situations, e.g., coupled to one or several of the following elements: a capacitor, an inductor (in a superconducting ring), and an applied current source. By solving an effective Shrödinger equation, we have obtained squeezed vacuum (coherent) states as the ground states of a ``free-oscillating'' (linearly-driven) Josephson junction, and calculated the uncertainties of its canonical momentum, charge, and coordinate, phase. We have also shown that the excited states of the various systems we consider are similar to the number states of a simple harmonic oscillator but with different fluctuation properties. Furthermore, we have obtained the time-evolution operators for these systems. These operators can make it easier to calculate the time-dependence of the expectation values and fluctuations of various quantities starting from an arbitrary initial state.

  8. Relative resistance of long junctional epithelial adhesions and connective tissue attachments to plaque-induced inflammation.

    PubMed

    Beaumont, R H; O'Leary, T J; Kafrawy, A H

    1984-04-01

    This study compared the resistance to periodontal disease of the long junctional epithelial adhesion and the naturally occurring dentogingival junction. Two groups were used, each containing three young male beagle dogs with all permanent teeth erupted. Periodontitis was induced around maxillary and mandibular premolars in the experimental dogs over a 42-day period, using subgingival ligatures and a soft diet. Fourteen days after ligature removal, flaps were reflected, granulation tissue was removed and the roots were planed to the alveolar crest. Reference grooves were placed in the root surfaces at the level of the alveolar bone, the flaps were positioned over the alveolar crests, and sutures were placed. A 60-day period permitted healing with formation of long junctional epithelial adhesions. During this 116-day period control dogs were maintained in gingival health by daily brushing and by prophylaxis every 14 days. Both groups had a high level of health (GI scores of 0) at the beginning of the 20-day combined disease phase. Inflammation was induced in both groups by subgingival ligature placement and a plaque-promoting diet. Right and left sides of both groups represented separate time intervals within the 20-day period. Block sections were secured at time of killing and the tissues were prepared for light and fluorescent microscopic evaluation. Mean GI scores and mean probing depths increased similarly in both groups. Tagge index scores of gingival inflammation were higher at the longer time periods in the experimental animals. However, they displayed an intact long junctional epithelial adhesion throughout the study, while control animals frequently showed ulceration of the sulcular epithelium. Neither group showed significant changes in location of the apical cells of the attachment epithelium. Crestal osteoblastic activity, confirmed with Procion labeling, predominated in the experimental animals, while osteoclastic activity predominated in the control

  9. The characteristics of railway service disruption: implications for disruption management.

    PubMed

    Golightly, D; Dadashi, N

    2017-03-01

    Rail disruption management is central to operational continuity and customer satisfaction. Disruption is not a unitary phenomenon - it varies by time, cause, location and complexity of coordination. Effective, user-centred technology for rail disruption must reflect this variety. A repertory grid study was conducted to elicit disruption characteristics. Construct elicitation with a group of experts (n = 7) captured 26 characteristics relevant to rail disruption. A larger group of operational staff (n = 28) rated 10 types of rail incident against the 26 characteristics. The results revealed distinctions such as business impact and public perception, and the importance of management of the disruption over initial detection. There were clear differences between those events that stop the traffic, as opposed to those that only slow the traffic. The results also demonstrate the utility of repertory grid for capturing the characteristics of complex work domains. Practitioner Summary: The aim of the paper is to understand how variety in rail disruption influences socio-technical design. It uses repertory grid to identify and prioritise 26 constructs, and group 10 disruption types, identifying critical factors such as whether an incident stops or merely slows the service, and business reputation.

  10. Sulfate transport in apical membrane vesicles isolated from tracheal epithelium

    SciTech Connect

    Elgavish, A.; DiBona, D.R.; Norton, P.; Meezan, E.

    1987-09-01

    Sulfate uptake in apical membrane vesicles isolated from bovine tracheal epithelium is shown to occur into an osmotically sensitive intravesicular space, via a carrier-mediated system. This conclusion is based on three lines of evidence: 1) saturation kinetics: 2) substrate specificity; and 3) inhibition by the anion transport inhibitors SITS and DIDS. The affinity of the transport system is highest in low ionic strength media and decreases in the presence of gluconate. Chloride appears to cis-inhibit sulfate uptake and to trans-stimulate sulfate efflux. Cis-inhibition and trans-stimulation studies with a variety of anions indicate that this exchange system may be shared by HCO/sub 3//sup -/, S/sub 2/O/sub 3//sup 2 -/, SeO/sub 4//sup 2 -/, and MoO/sub 4//sup 2 -/ but not by H/sub 2/PO/sub 4//sup -/ or HAsO/sub 4//sup 2/. Studies indicate that protons may play two distinct roles in sulfate transport in this system. These studies show that the carrier-mediated system can function in the absence of chloride. The overshoot observed in the presence of a proton gradient indicates that under those conditions the mechanism of transport may be a SO/sub 4//sup 2 -/-OH/sup -/ exchange.

  11. Profilin Regulates Apical Actin Polymerization to Control Polarized Pollen Tube Growth.

    PubMed

    Liu, Xiaonan; Qu, Xiaolu; Jiang, Yuxiang; Chang, Ming; Zhang, Ruihui; Wu, Youjun; Fu, Ying; Huang, Shanjin

    2015-12-07

    Pollen tube growth is an essential step during flowering plant reproduction, whose growth depends on a population of dynamic apical actin filaments. Apical actin filaments were thought to be involved in the regulation of vesicle fusion and targeting in the pollen tube. However, the molecular mechanisms that regulate the construction of apical actin structures in the pollen tube remain largely unclear. Here, we identify profilin as an important player in the regulation of actin polymerization at the apical membrane in the pollen tube. Downregulation of profilin decreased the amount of filamentous actin and induced disorganization of apical actin filaments, and reduced tip-directed vesicle transport and accumulation in the pollen tube. Direct visualization of actin dynamics revealed that the elongation of actin filaments originating at the apical membrane decreased in profilin mutant pollen tubes. Mutant profilin that is defective in binding poly-L-proline only partially rescues the actin polymerization defect in profilin mutant pollen tubes, although it fully rescues the actin turnover phenotype. We propose that profilin controls the construction of actin structures at the pollen tube tip, presumably by favoring formin-mediated actin polymerization at the apical membrane.

  12. Microvillus inclusion disease: a genetic defect affecting apical membrane protein traffic in intestinal epithelium.

    PubMed

    Ameen, N A; Salas, P J

    2000-01-01

    The striking similarities between microvillus inclusions (MIs) in enterocytes in microvillus inclusion disease (MID) and vacuolar apical compartment in tissue culture epithelial cells, led us to analyze endoscopic biopsies of duodenal mucosa of a patient after the samples were used for diagnostic procedures. Samples from another patient with an unrelated disease were used as controls. The MID enterocytes showed a decrease in the thickness of the apical F-actin layer, and normal microtubules. The immunofluorescence analysis of the distribution of five apical membrane markers (sucrase isomaltase, alkaline phosphatase, NHE-3 Na+/H+ exchanger, cGMP-dependent protein kinase, and cystic fibrosis trans-membrane conductance regulator), showed low levels of these proteins in their standard localization at the apical membrane as compared with normal duodenal epithelium processed in parallel. Instead, four of these markers were found in a diffuse distribution in the apical cytoplasm, below the terminal web (as indicated by co-localization with F-actin and cytokeratin 19), and in MIs as well. The basolateral protein Na(+)-K+ATPase, in contrast, was normally localized. These results support the hypothesis that MID may represent the first genetic defect affecting apical membrane traffic, possibly in a late step of apical exocytosis.

  13. The Apical Complex Provides a Regulated Gateway for Secretion of Invasion Factors in Toxoplasma

    PubMed Central

    Katris, Nicholas J.; van Dooren, Giel G.; McMillan, Paul J.; Hanssen, Eric; Tilley, Leann; Waller, Ross F.

    2014-01-01

    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. PMID:24743791

  14. The fast-recycling receptor Megalin defines the apical recycling pathway of epithelial cells

    PubMed Central

    Perez Bay, Andres E.; Schreiner, Ryan; Benedicto, Ignacio; Paz Marzolo, Maria; Banfelder, Jason; Weinstein, Alan M.; Rodriguez-Boulan, Enrique J.

    2016-01-01

    The basolateral recycling and transcytotic pathways of epithelial cells were previously defined using markers such as transferrin (TfR) and polymeric IgA (pIgR) receptors. In contrast, our knowledge of the apical recycling pathway remains fragmentary. Here we utilize quantitative live-imaging and mathematical modelling to outline the recycling pathway of Megalin (LRP-2), an apical receptor with key developmental and renal functions, in MDCK cells. We show that, like TfR, Megalin is a long-lived and fast-recycling receptor. Megalin enters polarized MDCK cells through segregated apical sorting endosomes and subsequently intersects the TfR and pIgR pathways at a perinuclear Rab11-negative compartment termed common recycling endosomes (CRE). Whereas TfR recycles to the basolateral membrane from CRE, Megalin, like pIgR, traffics to subapical Rab11-positive apical recycling endosomes (ARE) and reaches the apical membrane in a microtubule- and Rab11-dependent manner. Hence, Megalin defines the apical recycling pathway of epithelia, with CRE as its apical sorting station. PMID:27180806

  15. Molecular characterization of the apical organ of the anthozoan Nematostella vectensis

    PubMed Central

    Sinigaglia, Chiara; Busengdal, Henriette; Lerner, Avi; Oliveri, Paola; Rentzsch, Fabian

    2015-01-01

    Apical organs are sensory structures present in many marine invertebrate larvae where they are considered to be involved in their settlement, metamorphosis and locomotion. In bilaterians they are characterised by a tuft of long cilia and receptor cells and they are associated with groups of neurons, but their relatively low morphological complexity and dispersed phylogenetic distribution have left their evolutionary relationship unresolved. Moreover, since apical organs are not present in the standard model organisms, their development and function are not well understood. To provide a foundation for a better understanding of this structure we have characterised the molecular composition of the apical organ of the sea anemone Nematostella vectensis. In a microarray-based comparison of the gene expression profiles of planulae with either a wildtype or an experimentally expanded apical organ, we identified 78 evolutionarily conserved genes, which are predominantly or specifically expressed in the apical organ of Nematostella. This gene set comprises signalling molecules, transcription factors, structural and metabolic genes. The majority of these genes, including several conserved, but previously uncharacterized ones, are potentially involved in different aspects of the development or function of the long cilia of the apical organ. To demonstrate the utility of this gene set for comparative analyses, we further analysed the expression of a subset of previously uncharacterized putative orthologs in sea urchin larvae and detected expression for twelve out of eighteen of them in the apical domain. Our study provides a molecular characterization of the apical organ of Nematostella and represents an informative tool for future studies addressing the development, function and evolutionary history of apical organ cells. PMID:25478911

  16. Molecular characterization of the apical organ of the anthozoan Nematostella vectensis.

    PubMed

    Sinigaglia, Chiara; Busengdal, Henriette; Lerner, Avi; Oliveri, Paola; Rentzsch, Fabian

    2015-02-01

    Apical organs are sensory structures present in many marine invertebrate larvae where they are considered to be involved in their settlement, metamorphosis and locomotion. In bilaterians they are characterised by a tuft of long cilia and receptor cells and they are associated with groups of neurons, but their relatively low morphological complexity and dispersed phylogenetic distribution have left their evolutionary relationship unresolved. Moreover, since apical organs are not present in the standard model organisms, their development and function are not well understood. To provide a foundation for a better understanding of this structure we have characterised the molecular composition of the apical organ of the sea anemone Nematostella vectensis. In a microarray-based comparison of the gene expression profiles of planulae with either a wildtype or an experimentally expanded apical organ, we identified 78 evolutionarily conserved genes, which are predominantly or specifically expressed in the apical organ of Nematostella. This gene set comprises signalling molecules, transcription factors, structural and metabolic genes. The majority of these genes, including several conserved, but previously uncharacterized ones, are potentially involved in different aspects of the development or function of the long cilia of the apical organ. To demonstrate the utility of this gene set for comparative analyses, we further analysed the expression of a subset of previously uncharacterized putative orthologs in sea urchin larvae and detected expression for twelve out of eighteen of them in the apical domain. Our study provides a molecular characterization of the apical organ of Nematostella and represents an informative tool for future studies addressing the development, function and evolutionary history of apical organ cells.

  17. Disruptive Youth Programs in Maryland.

    ERIC Educational Resources Information Center

    Walters, Peggy G.

    This document describes the work of the Pupil Services Branch of the Maryland State Department of Education in its efforts to assist school districts and individual schools in the state in examining the causes of student disruption and in developing programs that are aimed at impacting disruptive students and creating more effective schools. A…

  18. Adrenocortical endocrine disruption.

    PubMed

    Harvey, Philip W

    2016-01-01

    The adrenal has been neglected in endocrine disruption regulatory testing strategy. The adrenal is a vital organ, adrenocortical insufficiency is recognised in life threatening "adrenal crises" and Addison's disease, and the consequences of off-target toxicological inhibition of adrenocortical steroidogenesis is well recognised in clinical medicine, where drugs such as aminoglutethimide and etomidate killed patients via unrecognised inhibition of adrenocortical steroidogenic enzymes (e.g. CYP11B1) along the cortisol and aldosterone pathways. The consequences of adrenocortical dysfunction during early development are also recognised in the congenital salt wasting and adrenogenital syndromes presenting neonatally, yet despite a remit to focus on developmental and reproductive toxicity mechanisms of endocrine disruption by many regulatory agencies (USEPA EDSTAC; REACH) the assessment of adrenocortical function has largely been ignored. Further, every step in the adrenocortical steroidogenic pathway (ACTH receptor, StAR, CYP's 11A1, 17, 21, 11B1, 11B2, and 3-hydroxysteroid dehydrogenase Δ4,5 isomerase) is known to be a potential target with multiple examples of chemicals inhibiting these targets. Many of these chemicals have been detected in human and wildlife tissues. This raises the question of whether exposure to low level environmental chemicals may be affecting adrenocortical function. This review examines the omission of adrenocortical testing in the current regulatory frameworks; the characteristics that make the adrenal cortex particularly vulnerable to toxic insult; chemicals and their toxicological targets within the adrenocortical steroidogenic pathways; the typical manifestations of adrenocortical toxicity (e.g. human iatrogenically induced pharmacotoxicological adrenal insufficiency, manifestations in typical mammalian regulatory general toxicology studies, manifestations in wildlife) and models of adrenocortical functional assessment. The utility of the

  19. Identification of the Moving Junction Complex of Toxoplasma gondii: A Collaboration between Distinct Secretory Organelles

    PubMed Central

    2005-01-01

    Apicomplexan parasites, including Toxoplasma gondii and Plasmodium sp., are obligate intracellular protozoa. They enter into a host cell by attaching to and then creating an invagination in the host cell plasma membrane. Contact between parasite and host plasma membranes occurs in the form of a ring-shaped moving junction that begins at the anterior end of the parasite and then migrates posteriorly. The resulting invagination of host plasma membrane creates a parasitophorous vacuole that completely envelops the now intracellular parasite. At the start of this process, apical membrane antigen 1 (AMA1) is released onto the parasite surface from specialized secretory organelles called micronemes. The T. gondii version of this protein, TgAMA1, has been shown to be essential for invasion but its exact role has not previously been determined. We identify here a trio of proteins that associate with TgAMA1, at least one of which associates with TgAMA1 at the moving junction. Surprisingly, these new proteins derive not from micronemes, but from the anterior secretory organelles known as rhoptries and specifically, for at least two, from the neck portion of these club-shaped structures. Homologues for these AMA1-associated proteins are found throughout the Apicomplexa strongly suggesting that this moving junction apparatus is a conserved feature of this important class of parasites. Differences between the contributing proteins in different species may, in part, be the result of selective pressure from the different niches occupied by these parasites. PMID:16244709

  20. Self-Organizing Actomyosin Patterns on the Cell Cortex at Epithelial Cell-Cell Junctions

    PubMed Central

    Moore, Thomas; Wu, Selwin K.; Michael, Magdalene; Yap, Alpha S.; Gomez, Guillermo A.; Neufeld, Zoltan

    2014-01-01

    The behavior of actomyosin critically determines morphologically distinct patterns of contractility found at the interface between adherent cells. One such pattern is found at the apical region (zonula adherens) of cell-cell junctions in epithelia, where clusters of the adhesion molecule E-cadherin concentrate in a static pattern. Meanwhile, E-cadherin clusters throughout lateral cell-cell contacts display dynamic movements in the plane of the junctions. To gain insight into the principles that determine the nature and organization of these dynamic structures, we analyze this behavior by modeling the 2D actomyosin cell cortex as an active fluid medium. The numerical simulations show that the stability of the actin filaments influences the spatial structure and dynamics of the system. We find that in addition to static Turing-type patterns, persistent dynamic behavior occurs in a wide range of parameters. In the 2D model, mechanical stress-dependent actin breakdown is shown to produce a continuously changing network of actin bridges, whereas with a constant breakdown rate, more isolated clusters of actomyosin tend to form. The model qualitatively reproduces the dynamic and stable patterns experimentally observed at the junctions between epithelial cells. PMID:25468344

  1. Alix-mediated assembly of the actomyosin–tight junction polarity complex preserves epithelial polarity and epithelial barrier

    PubMed Central

    Campos, Yvan; Qiu, Xiaohui; Gomero, Elida; Wakefield, Randall; Horner, Linda; Brutkowski, Wojciech; Han, Young-Goo; Solecki, David; Frase, Sharon; Bongiovanni, Antonella; d'Azzo, Alessandra

    2016-01-01

    Maintenance of epithelial cell polarity and epithelial barrier relies on the spatial organization of the actin cytoskeleton and proper positioning/assembly of intercellular junctions. However, how these processes are regulated is poorly understood. Here we reveal a key role for the multifunctional protein Alix in both processes. In a knockout mouse model of Alix, we identified overt structural changes in the epithelium of the choroid plexus and in the ependyma, such as asymmetrical cell shape and size, misplacement and abnormal beating of cilia, blebbing of the microvilli. These defects culminate in excessive cell extrusion, enlargement of the lateral ventricles and hydrocephalus. Mechanistically, we find that by interacting with F-actin, the Par complex and ZO-1, Alix ensures the formation and maintenance of the apically restricted actomyosin–tight junction complex. We propose that in this capacity Alix plays a role in the establishment of apical–basal polarity and in the maintenance of the epithelial barrier. PMID:27336173

  2. Potassium ion recycling pathway via gap junction systems in the mammalian cochlea and its interruption in hereditary nonsyndromic deafness.

    PubMed

    Kikuchi, T; Adams, J C; Miyabe, Y; So, E; Kobayashi, T

    2000-01-01

    In the mammalian cochlea, there are two independent gap junction systems, the epithelial cell gap junction system and the connective tissue cell gap junction system. Thus far, four different connexin molecules, including connexin 26, 30, 31, and 43, have been reported in the cochlea. The two networks of gap junctions form the route by which K+ ions that pass through the sensory cells during mechanosensory transduction can be recycled back to the endolymphatic space, from which they reenter the sensory cells. Activation of hair cells by acoustic stimuli induces influx of K+ ions from the endolymph to sensory hair cells. These K+ ions are released basolaterally to the extracellular space of the organ of Corti, from which they enter the cochlear supporting cells. Once inside the supporting cells they move via the epithelial cell gap junction system laterally to the lower part of the spiral ligament. The K+ ions are released into the extracellular space of the spiral ligament by root cells and taken up by type II fibrocytes. This uptake incorporates K+ into the connective tissue gap junction system. Within this system, the K+ ions pass through the tight junctional barrier of the stria vascularis and are released within the intrastrial extracellular space. The marginal cells of the stria vascularis then take up K+ and return it to the endolymphatic space, where it can be used again in sensory transduction. It is highly probable that mutations of connexin genes that result in human nonsyndromic deafness cause dysfunction of cochlear gap junctions and thereby interrupt K+ ion recirculation pathways. In addition to connexin mutations, other conditions may disrupt gap junctions within the ear. For example, mice with a functionally significant mutation of Brain-4, which is expressed in the connective tissue cells within the cochlea, show marked depression of the endolymphatic potential and profound sensorineural hearing loss. It seems likely that disruption of connective

  3. Proteomic mapping of ER-PM junctions identifies STIMATE as regulator of Ca2+ influx

    PubMed Central

    Jing, Ji; He, Lian; Sun, Aomin; Quintana, Ariel; Ding, Yuehe; Ma, Guolin; Tan, Peng; Liang, Xiaowen; Zheng, Xiaolu; Chen, Liangyi; Shi, Xiaodong; Zhang, Shenyuan L.; Zhong, Ling; Huang, Yun; Dong, Meng-Qiu; Walker, Cheryl L.; Hogan, Patrick G.; Wang, Youjun; Zhou, Yubin

    2015-01-01

    Specialized junctional sites that connect the plasma membrane (PM) and endoplasmic reticulum (ER) play critical roles in controlling lipid metabolism and Ca2+ signaling1–4. Store operated Ca2+ entry mediated by dynamic STIM1-ORAI1 coupling represents a classical molecular event occurring at ER-PM junctions, but the protein composition and how previously-unrecognized protein regulators facilitate this process remain ill-defined. Using a combination of spatially-restricted biotin-labelling in situ coupled with mass spectrometry5, 6 and a secondary screen based on bimolecular fluorescence complementation7, we mapped the proteome of intact ER-PM junctions in living cells without disrupting their architectural integrity. Our approaches lead to the discovery of an ER-resident multi-transmembrane protein that we call STIMATE (STIM-activating enhancer, encoded by TMEM110) as a positive regulator of Ca2+ influx in vertebrates. STIMATE physically interacts with STIM1 to promote STIM1 conformational switch. Genetic depletion of STIMATE substantially reduces STIM1 puncta formation at ER-PM junctions and suppresses the Ca2+-NFAT signaling. Our findings enable further genetic studies to elucidate the function of STIMATE in normal physiology and disease, and set the stage to uncover more uncharted functions of hitherto underexplored ER-PM junctions. PMID:26322679

  4. Distribution of the feline calicivirus receptor junctional adhesion molecule a in feline tissues.

    PubMed

    Pesavento, P A; Stokol, T; Liu, H; van der List, D A; Gaffney, P M; Parker, J S

    2011-03-01

    Junctional adhesion molecule A (JAM-A) is an immunoglobulin superfamily protein that plays an important role in the assembly and maintenance of tight junctions and the establishment of epithelial cell polarity. The feline JAM-A (fJAM-A) is a functional receptor for feline calicivirus (FCV). Among natural diseases associated with FCV infection, isolates that cause oral vesicular disease are detected in epithelial cells; however, isolates that cause systemic disease are detected in multiple cell types. The distribution of an FCV receptor or receptors in feline tissues is relevant to viral pathogenesis in that it should reflect the wide latitude of clinical sequelae associated with FCV infection. The authors examined the expression of feline JAM-A in the cat by using confocal immunofluorescence localization on normal tissues, with special regard to tissue targets of naturally occurring FCV. As described in the human and the mouse, fJAM-A was widely distributed in feline tissues, where it localized at cell-cell junctions of epithelial and endothelial cells. fJAM-A was highly expressed on feline platelets, with lower levels of expression on feline peripheral blood leukocytes. Additionally, FCV infection of a feline epithelial cell monolayer causes redistribution of fJAM-A to the cytosol of infected cells. It is reasonable to propose that the spectrum of lesions caused by FCV reflects disruption of intercellular junctions that rely on fJAM-A function and tight junctional integrity.

  5. The Dissolution of Double Holliday Junctions

    PubMed Central

    Bizard, Anna H.; Hickson, Ian D.

    2014-01-01

    Double Holliday junctions (dHJS) are important intermediates of homologous recombination. The separate junctions can each be cleaved by DNA structure-selective endonucleases known as Holliday junction resolvases. Alternatively, double Holliday junctions can be processed by a reaction known 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. PMID:24984776

  6. Physics and Applications of NIS Junctions

    SciTech Connect

    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.

  7. In vitro formation of gap junction vesicles.

    PubMed

    Goodenough, D A

    1976-02-01

    A method is described that uses trypsin digestion combined with collagenase-hyaluronidase which produces a population of gap junction vesicles. The hexagonal lattice of subunits ("connexons") comprising the gapjunctions appears unaltered by various structural criteria and by buoyant density measurements. The gap junction vesciles are closed by either a single or a double profile of nonjunctional "membrane," which presents a smooth, particle-free fracture face. Horseradish peroxidase and cytochrome c studies have revealed that about 20% of the gap junction vesicles are impermeable to proteins 12,000 daltons or larger. The increased purity of the trypsinized junction preparation suggests that one of the disulfide reduction products of the gap-junction principal protein may be a nonjunctional contaminating peptide. The gap junction appears to be composed of a single 18,000-dalton protein, connexin, which may be reduced to a single 9,000-dalton peak. The number of peptides in this reduced peak are still unknown.

  8. The expression of gingival epithelial junctions in response to subgingival biofilms.

    PubMed

    Belibasakis, Georgios N; Kast, Jeannette I; Thurnheer, Thomas; Akdis, Cezmi A; Bostanci, Nagihan

    2015-01-01

    Periodontitis is an infectious inflammatory disease that destroys the tooth-supporting tissues. It is caused by the formation of subgingival biofilms on the surface of the tooth. Characteristic bacteria associated with subgingival biofilms are the Gram-negative anaerobes Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola, collectively known as the "red complex" species. Inter-epithelial junctions ensure the barrier integrity of the gingival epithelium. This may however be disrupted by the biofilm challenge. The aim of this in vitro study was to investigate the effect of subgingival biofilms on the expression of inter-epithelial junctions by gingival epithelia, and evaluate the relative role of the red complex. Multi-layered human gingival epithelial cultures were challenged with a 10-species in vitro subgingival biofilm model, or its variant without the red complex, for 3 h and 24 h. A low-density array microfluidic card platform was then used for analyzing the expression of 62 genes encoding for tight junctions, gap junctions, adherens junctions, and desmosomes. Although there was a limited effect of the biofilms on the expression of tight, adherens and gap junctions, the expression of a number of desmosomal components was affected. In particular, Desmoglein-1 displayed a limited and transient up-regulation in response to the biofilm. In contrast, Desmocollin-2, Desmoplakin and Plakoglobin were down-regulated equally by both biofilm variants, after 24 h. In conclusion, this subgingival biofilm model may down-regulate selected desmosomal junctions in the gingival epithelium, irrespective of the presence of the "red complex." In turn, this could compromise the structural integrity of the gingival tissue, favoring bacterial invasion and chronic infection.

  9. The expression of gingival epithelial junctions in response to subgingival biofilms

    PubMed Central

    Belibasakis, Georgios N; Kast, Jeannette I; Thurnheer, Thomas; Akdis, Cezmi A; Bostanci, Nagihan

    2015-01-01

    Periodontitis is an infectious inflammatory disease that destroys the tooth-supporting tissues. It is caused by the formation of subgingival biofilms on the surface of the tooth. Characteristic bacteria associated with subgingival biofilms are the Gram-negative anaerobes Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola, collectively known as the “red complex” species. Inter-epithelial junctions ensure the barrier integrity of the gingival epithelium. This may however be disrupted by the biofilm challenge. The aim of this in vitro study was to investigate the effect of subgingival biofilms on the expression of inter-epithelial junctions by gingival epithelia, and evaluate the relative role of the red complex. Multi-layered human gingival epithelial cultures were challenged with a 10-species in vitro subgingival biofilm model, or its variant without the red complex, for 3 h and 24 h. A low-density array microfluidic card platform was then used for analyzing the expression of 62 genes encoding for tight junctions, gap junctions, adherens junctions, and desmosomes. Although there was a limited effect of the biofilms on the expression of tight, adherens and gap junctions, the expression of a number of desmosomal components was affected. In particular, Desmoglein-1 displayed a limited and transient up-regulation in response to the biofilm. In contrast, Desmocollin-2, Desmoplakin and Plakoglobin were down-regulated equally by both biofilm variants, after 24 h. In conclusion, this subgingival biofilm model may down-regulate selected desmosomal junctions in the gingival epithelium, irrespective of the presence of the “red complex.” In turn, this could compromise the structural integrity of the gingival tissue, favoring bacterial invasion and chronic infection. PMID:26305580

  10. Modeling the Morphometric Evolution of the Maize Shoot Apical Meristem

    PubMed Central

    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. PMID:27867389

  11. Can loss of apical dominance in potato tuber serve as a marker of physiological age?

    PubMed Central

    Eshel, Dani; Teper-Bamnolker, Paula

    2012-01-01

    The potato tuber constitutes a model system for the study of dormancy release and sprouting, suggested to be regulated by endogenous plant hormones and their balance inside the tuber. During dormancy, potato tubers cannot be induced to sprout without some form of stress or exogenous hormone treatment. When dormancy is released, sprouting of the apical bud may be inhibited by sprout control agents or cold temperature. Dominance of the growing apical bud over other lateral buds decreases during storage and is one of the earliest morphophysiological indicators of the tuber's physiological age. Three main types of loss of apical dominance (AD) affect sprouting shape. Hallmarks of programmed cell death (PCD) have been identified in the tuber apical bud meristem (TAB-meristem) during normal growth, and are more extensive when AD is lost following extended cold storage or chemical stress. Nevertheless, the role of hormonal regulation in TAB-meristem PCD remains unclear. PMID:22899056

  12. Purification of basolateral integral membrane proteins by cationic colloidal silica-based apical membrane subtraction.

    PubMed

    Goode, Robert J A; Simpson, Richard J

    2009-01-01

    Epithelial cell polarity mediates many essential biological functions and perturbation of the apical/basolateral divide is a hallmark of epithelial to mesenchymal transition in carcinoma. Therefore, correct targeting of proteins to the apical and basolateral surfaces is essential to proper epithelial cell function. However, proteomic characterisation of apical/basolateral sorting has been largely ignored, due to ineffectual separation techniques and contamination of plasma-membrane preparations with housekeeping proteins. Here we describe a method that strips the apical membrane from the adherent cells and releases the intracellular contents, thereby leaving the basolateral membrane available for stringent washes and collection. Analysis of the basolateral membrane of an adherent colon adenocarcinoma cell line resulted in 66% of identified proteins being integral membrane proteins, which possessed either a transmembrane domain or lipid modification, including 35 CD antigens. Based on the abundance of peptides from basolateral marker proteins, this method efficiently captures basolateral integral membrane proteins, with minimal contamination from other membranes and basic proteins.

  13. All That Glitters is not Gold: Apical Hypertrophic Cardiomyopathy Mimicking Acute Coronary Syndrome

    PubMed Central

    Lakshmanadoss, Umashankar; Kulkarni, Abhishek; Balakrishnan, Shobana; Shree, Nidhi; Harjai, Kishore; Jagasia, Dinesh

    2012-01-01

    Hypertrophic cardiomyopathy is characterized by the idiopathic hypertrophy of the left ventricle (and occasionally right ventricle). HCM is an autosomal dominant disease, with variable penetration. In Asian population, apical hypertrophic cardiomyopathy is relatively common (25%). However, this is relatively rare in Caucasian population (0.2%). Patients with HCM, often presents with typical exertional chest pain and shortness of breath. Apical HCM patients tend to have milder symptoms. However, the clinical presentation and electrocardiographic features of Apical HCM often mimic acute coronary syndrome and high index of suspicion is warranted in differentiating this condition. Patients with apical HCM have relatively better prognosis when compare to the other varieties. Here, we are presenting a patient who presented with typical exertional chest pain whose electrocardiographic changes are concerning for acute ischemic changes.

  14. Tissue response following CO2 laser application in apical surgery: light microscopic assessment in dogs.

    PubMed

    Friedman, S; Rotstein, I; Bab, I

    1992-01-01

    The potential advantages of CO2 laser in apical surgery have not been established histologically. Therefore, the long-term effects of CO2 laser on the apical and periapical tissues were examined histologically in dogs 6 months after apical surgery. Lased specimens and unlased controls showed periapical inflammatory and osteogenic reactions. Lased root surfaces revealed craters with a superficial charred layer closely associated with new cementum-like matrix. The subjacent dentin appeared tubule-free and eosinophilic. Lased bone trabeculae showed a charred layer with a deeper osteocyte-free zone. The charred layer was covered by new bone. Detached charred segments in the marrow space and periapical inflammatory infiltrate were intimately associated with multinucleated giant cells, some containing minute char particles. Such cells were absent from the root and trabecular char linings. In addition, the charred surfaces were free of hard tissue resorption. These results suggest that CO2 laser does not hinder healing when applied in apical surgery.

  15. [Gap junctions and cancer: implications and perspectives].

    PubMed

    Mesnil, Marc

    2004-02-01

    Gap junctions are made of intercellular channels which permit the diffusion from cytoplasm to cytoplasm of small hydrophilic molecules (<1,200 Da) such as ions, sugars, amino acids, nucleotides, second messengers (calcium, inositol triphosphate, etc.). Since their discovery in the early sixties, several groups have described the loss of their function in cancer cells. The accumulation of such data led to the hypothesis that gap junctions are involved in the carcinogenesis process. This assumption has been confirmed by data establishing that gap junctional intercellular communication is inhibited by most of the tumor promoters and that the restoration of such a communication, by transfection of cDNAs encoding gap junction proteins (connexins), inhibits the aberrant growth rates of tumorigenic cells. Despite these important informations, several fundamental questions remain still open. First, we do not know how gap junctions mediate such a tumor suppressor effect and whether it may depend either on the cell type or on the connexin type. Moreover, most of the data concerning a possible involvement of gap junctions in carcinogenesis have been obtained from in vitro and animal models. The very few results which have been currently collected from human tumors are not sufficient to have a clear idea concerning the real involvement of gap junctions in sporadic human cancers. These points as well as other unresolved questions about the role of gap junctional intercellular communication in carcinogenesis are mentioned. To bring some answers, some prospects are proposed with the objective to use gap junctions for increasing the effect of anticancer therapies.

  16. Magnetic tunnel junction pattern technique

    NASA Astrophysics Data System (ADS)

    Chen, Eugene; Schwarz, Benjamin; Choi, Chang Ju; Kula, Witold; Wolfman, Jerome; Ounadjela, Kamel; Geha, Sam

    2003-05-01

    We have developed a magnetic tunnel junction (MTJ) pattern technique that involves transforming the magnetic layer above the tunnel barrier in unwanted areas into an insulator, thus providing insulation between different MTJ devices without suffering common tunnel barrier shorting problems. With this technique, 90%-100% yielding MTJ devices have been observed. MTJ results using this process are superior to an etching based process. Switching distribution of patterned magnetic bits is also narrower using this novel technique. Process control and the ability to stop on the tunnel barrier have been demonstrated.

  17. Thermoelectric effects in nanoscale junctions.

    PubMed

    Dubi, Yonatan; Di Ventra, Massimiliano

    2009-01-01

    Despite its intrinsic nonequilibrium origin, thermoelectricity in nanoscale systems is usually described within a static scattering approach which disregards the dynamical interaction with the thermal baths that maintain energy flow. Using the theory of open quantum systems, we show instead that unexpected properties, such as a resonant structure and large sign sensitivity, emerge if the nonequilibrium nature of this problem is considered. Our approach also allows us to define and study a local temperature, which shows hot spots and oscillations along the system according to the coupling of the latter to the electrodes. This demonstrates that Fourier's lawa paradigm of statistical mechanicsis generally violated in nanoscale junctions.

  18. Method for shallow junction formation

    DOEpatents

    Weiner, K.H.

    1996-10-29

    A doping sequence is disclosed that reduces the cost and complexity of forming source/drain regions in complementary metal oxide silicon (CMOS) integrated circuit technologies. The process combines the use of patterned excimer laser annealing, dopant-saturated spin-on glass, silicide contact structures and interference effects creates by thin dielectric layers to produce source and drain junctions that are ultrashallow in depth but exhibit low sheet and contact resistance. The process utilizes no photolithography and can be achieved without the use of expensive vacuum equipment. The process margins are wide, and yield loss due to contact of the ultrashallow dopants is eliminated. 8 figs.

  19. Method for shallow junction formation

    DOEpatents

    Weiner, Kurt H.

    1996-01-01

    A doping sequence that reduces the cost and complexity of forming source/drain regions in complementary metal oxide silicon (CMOS) integrated circuit technologies. The process combines the use of patterned excimer laser annealing, dopant-saturated spin-on glass, silicide contact structures and interference effects creates by thin dielectric layers to produce source and drain junctions that are ultrashallow in depth but exhibit low sheet and contact resistance. The process utilizes no photolithography and can be achieved without the use of expensive vacuum equipment. The process margins are wide, and yield loss due to contact of the ultrashallow dopants is eliminated.

  20. The dynamics of soybean leaf and shoot apical meristem transcriptome undergoing floral initiation process.

    PubMed

    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

  1. Effect of needle insertion depth and apical diameter on irrigant extrusion in simulated immature permanent teeth.

    PubMed

    Aksel, Hacer; Askerbeyli, Sevinc; Canbazoglu, Cigdem; Serper, Ahmet

    2014-01-01

    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. Light and nitrogen nutrition regulate apical control in Rosa hybrida L.

    PubMed

    Furet, Pierre-Maxime; Lothier, Jérémy; Demotes-Mainard, Sabine; Travier, Sandrine; Henry, Clémence; Guérin, Vincent; Vian, Alain

    2014-03-01

    Apical control is defined as the inhibition of basal axillary bud outgrowth by an upper actively growing axillary axis, whose regulation is poorly understood yet differs markedly from the better-known apical dominance. We studied the regulation of apical control by environmental factors in decapitated Rosa hybrida in order to remove the apical hormonal influence and nutrient sink. In this plant model, all the buds along the main axis have a similar morphology and are able to burst in vitro. We concentrated on the involvement of light intensity and nitrate nutrition on bud break and axillary bud elongation in the primary axis pruned above the fifth leaf of each rose bush. We observed that apical control took place in low light (92 μmol m(-2)s(-1)), where only the 2-apical buds grew out, both in low (0.25 mM) and high (12.25 mM) nitrate. In contrast, in high light (453 μmol m(-2)s(-1)), the apical control only operates in low nitrate while all the buds along the stem grew out when the plant was supplied with a high level of nitrate. We found a decreasing photosynthetic activity from the top to the base of the plant concomitant with a light gradient along the stem. The quantity of sucrose, fructose, glucose and starch are higher in high light conditions in leaves and stem. The expression of the sucrose transporter RhSUC2 was higher in internodes and buds in this lighting condition, suggesting an increased capacity for sucrose transport. We propose that light intensity and nitrogen availability both contribute to the establishment of apical control.

  3. Tidal disruption event demographics

    NASA Astrophysics Data System (ADS)

    Kochanek, C. S.

    2016-09-01

    We survey the properties of stars destroyed in tidal disruption events (TDEs) as a function of black hole (BH) mass, stellar mass and evolutionary state, star formation history and redshift. For M_{BH} ≲ 10^7 M_{⊙}, the typical TDE is due to a M* ˜ 0.3 M⊙ M-dwarf, although the mass function is relatively flat for M_{ast } ≲ M_{⊙}. The contribution from older main-sequence stars and sub-giants is small but not negligible. From MBH ≃ 107.5-108.5 M⊙, the balance rapidly shifts to higher mass stars and a larger contribution from evolved stars, and is ultimately dominated by evolved stars at higher BH masses. The star formation history has little effect until the rates are dominated by evolved stars. TDE rates should decline very rapidly towards higher redshifts. The volumetric rate of TDEs is very high because the BH mass function diverges for low masses. However, any emission mechanism which is largely Eddington-limited for low BH masses suppresses this divergence in any observed sample and leads to TDE samples dominated by MBH ≃ 106.0-107.5 M⊙ BHs with roughly Eddington peak accretion rates. The typical fall-back time is relatively long, with 16 per cent having tfb < 10-1 yr (37 d), and 84 per cent having longer time-scales. Many residual rate discrepancies can be explained if surveys are biased against TDEs with these longer tfb, which seems very plausible if tfb has any relation to the transient rise time. For almost any BH mass function, systematic searches for fainter, faster time-scale TDEs in smaller galaxies, and longer time-scale TDEs in more massive galaxies are likely to be rewarded.

  4. Interception and disruption

    SciTech Connect

    Solem, J.C.

    1995-07-01

    Given sufficient warning we might try to avert a collision with a comet or asteroid by using beamed energy or by using the kinetic energy of an interceptor rocket. If motivated by the opportunity to convert the object into a space asset, perhaps a microgravity mine for construction materials or spacecraft fuels, we might try a rendezvous to implant a propulsion system of some sort. But the most cost-effective means of disruption is a nuclear explosive. In this paper, I discuss optimal tactics for terminal intercept, which can be extended to remote-interdiction scenarios as well. I show that the optimal mass ratio of an interceptor rock carrying a nuclear explosive depends mainly on the ratio of the exhaust velocity to the assailant-object closing velocity. I compare the effectiveness of stand-off detonation, surface burst, and penetration, for both deflection and pulverization, concluding that a penetrator has no clear advantage over a surface-burst device for deflection, but is a distinctly more capable pulverizer. The advantage of a stand-off device is to distribute the impulse more evenly over the surface of the object and to prevent fracture, an event which would greatly complicate the intercept problem. Finally, I present some results of a model for gravitationally bound objects and obtain the maximum non-fracturing deflection speed for a variety of object sizes and structures. For a single engagement, I conclude that the non-fracturing deflection speed obtainable with a stand-off device is about four times the speed obtainable with a surface-burst device. Furthermore, the non-fracturing deflection speed is somewhat dependent on the number of competent components of the object, the speed for a 13 component object being about twice that for a 135 component object.

  5. Endocrine Effects of Circadian Disruption.

    PubMed

    Bedrosian, Tracy A; Fonken, Laura K; Nelson, Randy J

    2016-01-01

    Disruption of circadian rhythms, provoked by artificial lighting at night, inconsistent sleep-wake schedules, and transmeridian air travel, is increasingly prevalent in modern society. Desynchrony of biological rhythms from environmental light cycles has dramatic consequences for human health. In particular, disrupting homeostatic oscillations in endocrine tissues and the hormones that these tissues regulate can have cascading effects on physiology and behavior. Accumulating evidence suggests that chronic disruption of circadian organization of endocrine function may lead to metabolic, reproductive, sleep, and mood disorders. This review discusses circadian control of endocrine systems and the consequences of distorting rhythmicity of these systems.

  6. Isotropic actomyosin dynamics promote organization of the apical cell cortex in epithelial cells

    PubMed Central

    Klingner, Christoph; Cherian, Anoop V.; Fels, Johannes; Diesinger, Philipp M.; Aufschnaiter, Roland; Maghelli, Nicola; Keil, Thomas; Beck, Gisela; Tolić-Nørrelykke, Iva M.; Bathe, Mark

    2014-01-01

    Although cortical actin plays an important role in cellular mechanics and morphogenesis, there is surprisingly little information on cortex organization at the apical surface of cells. In this paper, we characterize organization and dynamics of microvilli (MV) and a previously unappreciated actomyosin network at the apical surface of Madin–Darby canine kidney cells. In contrast to short and static MV in confluent cells, the apical surfaces of nonconfluent epithelial cells (ECs) form highly dynamic protrusions, which are often oriented along the plane of the membrane. These dynamic MV exhibit complex and spatially correlated reorganization, which is dependent on myosin II activity. Surprisingly, myosin II is organized into an extensive network of filaments spanning the entire apical membrane in nonconfluent ECs. Dynamic MV, myosin filaments, and their associated actin filaments form an interconnected, prestressed network. Interestingly, this network regulates lateral mobility of apical membrane probes such as integrins or epidermal growth factor receptors, suggesting that coordinated actomyosin dynamics contributes to apical cell membrane organization. PMID:25313407

  7. A Model of Differential Growth-Guided Apical Hook Formation in Plants.

    PubMed

    Žádníková, Petra; Wabnik, Krzysztof; Abuzeineh, Anas; Gallemi, Marçal; Van Der Straeten, Dominique; Smith, Richard S; Inzé, Dirk; Friml, Jiří; Prusinkiewicz, Przemysław; Benková, Eva

    2016-10-01

    Differential cell growth enables flexible organ bending in the presence of environmental signals such as light or gravity. A prominent example of the developmental processes based on differential cell growth is the formation of the apical hook that protects the fragile shoot apical meristem when it breaks through the soil during germination. Here, we combined in silico and in vivo approaches to identify a minimal mechanism producing auxin gradient-guided differential growth during the establishment of the apical hook in the model plant Arabidopsis thaliana Computer simulation models based on experimental data demonstrate that asymmetric expression of the PIN-FORMED auxin efflux carrier at the concave (inner) versus convex (outer) side of the hook suffices to establish an auxin maximum in the epidermis at the concave side of the apical hook. Furthermore, we propose a mechanism that translates this maximum into differential growth, and thus curvature, of the apical hook. Through a combination of experimental and in silico computational approaches, we have identified the individual contributions of differential cell elongation and proliferation to defining the apical hook and reveal the role of auxin-ethylene crosstalk in balancing these two processes.

  8. Effect of diode laser irradiation on the apical sealing of MTA retrofillings.

    PubMed

    de Souza, Eliana Barbosa; de Amorim, Crystiane Venditti Gomes; Marques, José Luiz Lage

    2006-01-01

    Apical sealing is essential for the success of paraendodontic surgery, so any procedure that may favor an adequate sealing of the apical remainder should be performed. The purpose of this study was to evaluate the influence of diode laser irradiation on the apical sealing of root-end cavities with MTA retrofillings. Root canals in twenty extracted human teeth were shaped with K-files and filled with gutta-percha. The apexes were cut off and root-end preparations were performed. The roots were divided randomly in 2 groups. Group 1 (ten specimens) was retrofilled with MTA. Group 2 was irradiated with diode laser, with 1 W for 20 seconds, on the apical surface and root end cavity before retrofilling with MTA. The specimens had their external surfaces impermeabilized with cyanoacrylate, except for the apical surface, and were then immersed in 1% rhodamine B dye for 72 h and placed in plaster stone. After that, the specimens were submitted to longitudinal abrasion until half of the root remained. The linear dye leakage was observed in these mid-roots between the root canal wall and retrofilling. The linear dye leakage was measured with Image Lab software, and the results were statistically analyzed with Student's t test. There were no statistically significant differences between the two groups (p > 0.05). The diode laser irradiation did not improve the apical sealing of MTA retrofillings under the conditions of this in vitro study.

  9. Vangl2 cooperates with Rab11 and Myosin V to regulate apical constriction during vertebrate gastrulation.

    PubMed

    Ossipova, Olga; Chuykin, Ilya; Chu, Chih-Wen; Sokol, Sergei Y

    2015-01-01

    Core planar cell polarity (PCP) proteins are well known to regulate polarity in Drosophila and vertebrate epithelia; however, their functions in vertebrate morphogenesis remain poorly understood. In this study, we describe a role for PCP signaling in the process of apical constriction during Xenopus gastrulation. The core PCP protein Vangl2 is detected at the apical surfaces of cells at the blastopore lip, and it functions during blastopore formation and closure. Further experiments show that Vangl2, as well as Daam1 and Rho-associated kinase (Rock), regulate apical constriction of bottle cells at the blastopore and ectopic constriction of ectoderm cells triggered by the actin-binding protein Shroom3. At the blastopore lip, Vangl2 is required for the apical accumulation of the recycling endosome marker Rab11. We also show that Rab11 and the associated motor protein Myosin V play essential roles in both endogenous and ectopic apical constriction, and might be involved in Vangl2 trafficking to the cell surface. Overexpression of Rab11 RNA was sufficient to partly restore normal blastopore formation in Vangl2-deficient embryos. These observations suggest that Vangl2 affects Rab11 to regulate apical constriction during blastopore formation.

  10. Proliferative effects of apical, but not basal, matrix metalloproteinase-7 activity in polarized MDCK cells

    SciTech Connect

    Harrell, Permila C.; McCawley, Lisa J.; Fingleton, Barbara; McIntyre, J. Oliver; Matrisian, Lynn M. . E-mail: lynn.matrisian@vanderbilt.edu

    2005-02-15

    Matrix metalloproteinase-7 (MMP-7) is primarily expressed in glandular epithelium. Therefore, its mechanism of action may be influenced by its regulated vectorial release to either the apical and/or basolateral compartments, where it would act on its various substrates. To gain a better understanding of where MMP-7 is released in polarized epithelium, we have analyzed its pattern of secretion in polarized MDCK cells expressing stably transfected human MMP-7 (MDCK-MMP-7), and HCA-7 and Caco2 human colon cancer cell lines. In all cell lines, latent MMP-7 was secreted to both cellular compartments, but was 1.5- to 3-fold more abundant in the basolateral compartment as compared to the apical. However, studies in the MDCK system demonstrated that MMP-7 activity was 2-fold greater in the apical compartment of MDCK-MMP-7{sup HIGH}-polarized monolayers, which suggests the apical co-release of an MMP-7 activator. In functional assays, MMP-7 over-expression increased cell saturation density as a result of increased cell proliferation with no effect on apoptosis. Apical MMP-7 activity was shown to be responsible for the proliferative effect, which occurred, as demonstrated by media transfer experiments, through cleavage of an apical substrate and not through the generation of a soluble factor. Taken together, our findings demonstrate the importance of MMP-7 secretion in relation to its mechanism of action when expressed in a polarized epithelium.

  11. Pak1 regulates the orientation of apical polarization and lumen formation by distinct pathways.

    PubMed

    deLeon, Orlando; Puglise, Jason M; Liu, Fengming; Smits, Jos; ter Beest, Martin B; Zegers, Mirjam M

    2012-01-01

    The development of the basic architecture of branching tubules enclosing a central lumen that characterizes most epithelial organs crucially depends on the apico-basolateral polarization of epithelial cells. Signals from the extracellular matrix control the orientation of the apical surface, so that it faces the lumen interior, opposite to cell-matrix adhesion sites. This orientation of the apical surface is thought to be intrinsically linked to the formation of single lumens. We previously demonstrated in three-dimensional cyst cultures of Madin-Darby canine kidney (MDCK) cells that signaling by β1 integrins regulates the orientation of the apical surface, via a mechanism that depends on the activity of the small GTPase Rac1. Here, we investigated whether the Rac1 effector Pak1 is a downstream effector in this pathway. Expression of constitutive active Pak1 phenocopies the effect of β1 integrin inhibition in that it misorients the apical surface and induces a multilumen phenotype. The misorientation of apical surfaces depends on the interaction of active Pak1 with PIX proteins and is linked to defects in basement membrane assembly. In contrast, the multilumen phenotype was independent of PIX and the basement membrane. Therefore, Pak1 likely regulates apical polarization and lumen formation by two distinct pathways.

  12. Pak1 Regulates the Orientation of Apical Polarization and Lumen Formation by Distinct Pathways

    PubMed Central

    Smits, Jos; ter Beest, Martin B.; Zegers, Mirjam M.

    2012-01-01

    The development of the basic architecture of branching tubules enclosing a central lumen that characterizes most epithelial organs crucially depends on the apico-basolateral polarization of epithelial cells. Signals from the extracellular matrix control the orientation of the apical surface, so that it faces the lumen interior, opposite to cell-matrix adhesion sites. This orientation of the apical surface is thought to be intrinsically linked to the formation of single lumens. We previously demonstrated in three-dimensional cyst cultures of Madin-Darby canine kidney (MDCK) cells that signaling by β1 integrins regulates the orientation of the apical surface, via a mechanism that depends on the activity of the small GTPase Rac1. Here, we investigated whether the Rac1 effector Pak1 is a downstream effector in this pathway. Expression of constitutive active Pak1 phenocopies the effect of β1 integrin inhibition in that it misorients the apical surface and induces a multilumen phenotype. The misorientation of apical surfaces depends on the interaction of active Pak1 with PIX proteins and is linked to defects in basement membrane assembly. In contrast, the multilumen phenotype was independent of PIX and the basement membrane. Therefore, Pak1 likely regulates apical polarization and lumen formation by two distinct pathways. PMID:22815903

  13. Histological assessment of pulp condition after apical vital root transection in one root of multirooted teeth in dogs: a preliminary study.

    PubMed

    Yaghmaiee, Massoud; Yavari, Amir Saeed; Mashhadiabbas, Fatemeh; Bahrami, Afshin; Farnia, Pupak; Sharifi, Davoud; Ghanavi, Jalaledin; Eslami, Behnan

    2007-09-01

    One of the most important aspects in surgery is the healing process after the periapical surgery. Past studies have shown occasional encounters with vital root resection and have noted varying degrees of pulpal response after root resection in periodontal disease. The purpose of this investigation was to observe the pulpal and periapical responses to intentional apical vital root transection in one root of multirooted teeth of German-Canadian dogs over a 6-month postoperative period. This is an experimental study performed on left maxillary and mandibular quadrants of four adult German-Canadian dogs after a 3- and 6-month period. Four teeth were assessed in each interval. One of the roots of multirooted teeth in the left quadrant of both maxillary and mandibular jaws was surgically transected. Tissue blocks were prepared by routine histological methods after 12 and 24 weeks after the surgery. The results showed a disruption of the normal pulpal architecture, with initial pulpal degeneration and subsequent early replacement by the periodontal ligament tissue after 24 weeks. Hypercementosis was seen around the apical portion of the root in all specimens. Pulpal regeneration was seen in the both upper and lower molars (p = 0.03). Resorption took place only in two specimens (p = 0.46). The inflammation in the 12th week was more than the 24th week. The pulp of multirooted teeth remains vital after transection of the apical part of the root in dogs. Longer follow-up periods are recommended because root canal therapy or extraction is indicated if resorption, necrosis, or ankylosis is seen.

  14. Canonical Wnt Signaling Regulates Atrioventricular Junction Programming and Electrophysiological Properties

    PubMed Central

    Gillers, Benjamin S; Chiplunkar, Aditi; Aly, Haytham; Valenta, Tomas; Basler, Konrad; Christoffels, Vincent M.; Efimov, Igor R; Boukens, Bastiaan J; Rentschler, Stacey

    2014-01-01

    Rationale Proper patterning of the atrioventricular canal (AVC) is essential for delay of electrical impulses between atria and ventricles, and defects in AVC maturation can result in congenital heart disease. Objective To determine the role of canonical Wnt signaling in the myocardium during AVC development. Methods and Results We utilized a novel allele of β-catenin that preserves β-catenin’s cell adhesive functions but disrupts canonical Wnt signaling, allowing us to probe the effects of Wnt loss of function independently. We show that loss of canonical Wnt signaling in the myocardium results in tricuspid atresia with hypoplastic right ventricle associated with loss of AVC myocardium. In contrast, ectopic activation of Wnt signaling was sufficient to induce formation of ectopic AV junction-like tissue as assessed by morphology, gene expression, and electrophysiologic criteria. Aberrant AVC development can lead to ventricular preexcitation, a characteristic feature of Wolff-Parkinson-White syndrome. We demonstrate that postnatal activation of Notch signaling downregulates canonical Wnt targets within the AV junction. Stabilization of β-catenin protein levels can rescue Notch-mediated ventricular preexcitation and dysregulated ion channel gene expression. Conclusions Our data demonstrate that myocardial canonical Wnt signaling is an important regulator of AVC maturation and electrical programming upstream of Tbx3. Our data further suggests that ventricular preexcitation may require both morphologic patterning defects, as well as myocardial lineage reprogramming, to allow robust conduction across accessory pathway tissue. PMID:25599332

  15. Electrodeposited, Transverse Nanowire Electroluminescent Junctions.

    PubMed

    Qiao, Shaopeng; Xu, Qiang; Dutta, Rajen K; Le Thai, Mya; Li, Xiaowei; Penner, Reginald M

    2016-09-27

    The preparation by electrodeposition of transverse nanowire electroluminescent junctions (tn-ELJs) is described, and the electroluminescence (EL) properties of these devices are characterized. The lithographically patterned nanowire electrodeposition process is first used to prepare long (millimeters), linear, nanocrystalline CdSe nanowires on glass. The thickness of these nanowires along the emission axis is 60 nm, and the width, wCdSe, along the electrical axis is adjustable from 100 to 450 nm. Ten pairs of nickel-gold electrical contacts are then positioned along the axis of this nanowire using lithographically directed electrodeposition. The resulting linear array of nickel-CdSe-gold junctions produces EL with an external quantum efficiency, EQE, and threshold voltage, Vth, that depend sensitively on wCdSe. EQE increases with increasing electric field and also with increasing wCdSe, and Vth also increases with wCdSe and, therefore, the electrical resistance of the tn-ELJs. Vth down to 1.8(±0.2) V (for wCdSe ≈ 100 nm) and EQE of 5.5(±0.5) × 10(-5) (for wCdSe ≈ 450 nm) are obtained. tn-ELJs produce a broad EL emission envelope, spanning the wavelength range from 600 to 960 nm.

  16. cAMP Promotes Cell Migration Through Cell Junctional Complex Dynamics and Actin Cytoskeleton Remodeling: Implications in Skin Wound Healing.

    PubMed

    Kim, Mi Ok; Ryu, Jung Min; Suh, Han Na; Park, Soo Hyun; Oh, Yeon-Mok; Lee, Sang Hun; Han, Ho Jae

    2015-11-01

    Stem cells have attracted great interest for their therapeutic capacity in tissue regeneration. Cyclic adenosine 3',5'-monophosphate (cAMP), existing in high concentration at wound sites, mediated various signaling pathways such as cytoskeleton dynamics, cell adhesion, and cell migration in stem cells, which suggest the critical roles of cAMP in the wound healing process through functional regulation of stem cells. However, the mechanisms behind the effect of cAMP on mouse embryonic stem cell (mESC) motility and its roles on skin wound healing remain to be fully elucidated. In the present study, 8-Bromo cAMP-treated mESCs showed significant wound closure and improved neovascularization. Moreover, 8-Bromo cAMP stimulated mESC migration into the wound bed. 8-Bromo cAMP also increased ESC motility in in vitro migration assay. 8-Bromo cAMP induced myosin light chain phosphorylation through Rac1 and Cdc42 signaling, which were involved in 8-Bromo cAMP-induced decrease in expression of junction proteins (connexin 43, E-cadherin, and occludin) at the plasma membrane. Subsequently, 8-Bromo cAMP induced the disruption of cell junctions (including gap junctions, adherens junctions, and tight junctions), which reduced the function of the gap junctions and cell adhesion. In addition, 8-Bromo cAMP-induced Rac1 and Cdc42 activation increased Arp3, TOCA, PAK, and N-WASP expression, but decreased cofilin phosphorylation level, which elicited actin cytoskeleton remodeling. In contrast to the control, 8-Bromo cAMP evoked a substantial migration of cells into the denuded area, which was blocked by the small interfering RNAs of the signaling pathway-related molecules or by inhibitors. In conclusion, cAMP enhanced the migration of mESCs through effective coordination of junctional disruption and actin cytoskeleton remodeling, which increased the wound healing capacity of ESCs.

  17. Deletion of collapsin response mediator protein 4 results in abnormal layer thickness and elongation of mitral cell apical dendrites in the neonatal olfactory bulb.

    PubMed

    Tsutiya, Atsuhiro; Watanabe, Hikaru; Nakano, Yui; Nishihara, Masugi; Goshima, Yoshio; Ohtani-Kaneko, Ritsuko

    2016-05-01

    Collapsin response mediator protein 4 (CRMP4), a member of the CRMP family, is involved in the pathogenesis of neurodevelopmental disorders such as schizophrenia and autism. Here, we first compared layer thickness of the olfactory bulb between wild-type (WT) and CRMP4-knockout (KO) mice. The mitral cell layer (MCL) was significantly thinner, whereas the external plexiform layer (EPL) was significantly thicker in CRMP4-KO mice at postnatal day 0 (PD0) compared with WTs. However, differences in layer thickness disappeared by PD14. No apoptotic cells were found in the MCL, and the number of mitral cells (MCs) identified with a specific marker (i.e. Tbx21 antibody) did not change in CRMP4-KO neonates. However, DiI-tracing showed that the length of mitral cell apical dendrites was greater in CRMP4-KO neonates than in WTs. In addition, expression of CRMP4 mRNA in WT mice was most abundant in the MCL at PD0 and decreased afterward. These results suggest that CRMP4 contributes to dendritic elongation. Our in vitro studies showed that deletion or knockdown of CRMP4 resulted in enhanced growth of MAP2-positive neurites, whereas overexpression of CRMP4 reduced their growth, suggesting a new role for CRMP4 as a suppressor of dendritic elongation. Overall, our data suggest that disruption of CRMP4 produces a temporary alteration in EPL thickness, which is constituted mainly of mitral cell apical dendrites, through the enhanced growth of these dendrites.

  18. Male reprotoxicity and endocrine disruption

    PubMed Central

    Campion, Sarah; Catlin, Natasha; Heger, Nicholas; McDonnell, Elizabeth V.; Pacheco, Sara E.; Saffarini, Camelia; Sandrof, Moses A.; Boekelheide, Kim

    2013-01-01

    Mammalian reproductive tract development is a tightly regulated process that can be disrupted following exposure to drugs, toxicants, endocrine disrupting chemicals or other compounds via alterations to gene and protein expression or epigenetic regulation. Indeed, the impacts of developmental exposure to certain toxicants may not be fully realized until puberty or adulthood when the reproductive tract becomes sexually mature and altered functionality is manifested. Exposures that occur later in life, once development is complete, can also disrupt the intricate hormonal and paracrine interactions responsible for adult functions, such as spermatogenesis. In this chapter, the biology and toxicology of the male reproductive tract is explored, proceeding through the various life stages including in utero development, puberty, adulthood and senescence. Special attention is given to the discussion of endocrine disrupting chemicals, chemical mixtures, low dose effects, transgenerational effects, and potential exposure-related causes of male reproductive tract cancers. PMID:22945574

  19. Neurotoxicity of Thyroid Disrupting Contaminants

    EPA Science Inventory

    Thyroid hormones playa critical role in the normal development ofthe mammalian brain. Thyroid disrupting chemicals (TDCs) are environmental contaminants that alter the structure or function ofthe thyroid gland, alter regulatory enzymes associated with thyroid hormone (TH) homeost...

  20. Tidal disruption of inviscid protoplanets

    NASA Technical Reports Server (NTRS)

    Boss, Alan P.; Cameron, A. G. W.; Benz, W.

    1991-01-01

    Roche showed that equilibrium is impossible for a small fluid body synchronously orbiting a primary within a critical radius now termed the Roche limit. Tidal disruption of orbitally unbound bodies is a potentially important process for planetary formation through collisional accumulation, because the area of the Roche limit is considerably larger then the physical cross section of a protoplanet. Several previous studies were made of dynamical tidal disruption and different models of disruption were proposed. Because of the limitation of these analytical models, we have used a smoothed particle hydrodynamics (SPH) code to model the tidal disruption process. The code is basically the same as the one used to model giant impacts; we simply choose impact parameters large enough to avoid collisions. The primary and secondary both have iron cores and silicate mantles, and are initially isothermal at a molten temperature. The conclusions based on the analytical and numerical models are summarized.

  1. Ultrasonic disruption of algae cells

    NASA Astrophysics Data System (ADS)

    King, P. M.; Nowotarski, K.; Joyce, E. M.; Mason, T. J.

    2012-05-01

    During last decade there has been increasing interest in the production of sustainable fuels from microalgae (R.H. Wijffels and M.J. Barbosa, 2010; Singh et al 2011; D.H. Lee 2011). The aim of this project was to determine if algal cells can be ultrasonically disrupted to release lipids for biofuel production. Ultrasonic disruption of two unicellular algal species: Dunnaliella salina and Nannochloropsis oculata was investigated using a 20 kHz probe. Haemocytometer, optical density, UV-Vis, fluoro-spectrophotometer and confocal microscopy results demonstrated complete cell destruction of Dunaliella salina within 16 minutes of sonication. Results obtained for Nannochloropsis oculata differed in that ultrasound dispersed clumped cells with little or no cell disruption, as observed by haemocytometer and confocal microscopy analysis. However, UV-Visible and fluoro-spectrophotometer analysis indicated chlorophyll release following sonication, suggesting some cell disruption had occurred.

  2. Shh pathway activation is present and required within the vertebrate limb bud apical ectodermal ridge for normal autopod patterning.

    PubMed

    Bouldin, Cortney M; Gritli-Linde, Amel; Ahn, Sohyun; Harfe, Brian D

    2010-03-23

    Expression of Sonic Hedgehog (Shh) in the posterior mesenchyme of the developing limb bud regulates patterning and growth of the developing limb by activation of the Hedgehog (Hh) signaling pathway. Through the analysis of Shh and Hh signaling target genes, it has been shown that activation in the limb bud mesoderm is required for normal limb development to occur. In contrast, it has been stated that Hh signaling in the limb bud ectoderm cannot occur because components of the Hh signaling pathway and Hh target genes have not been found in this tissue. However, recent array-based data identified both the components necessary to activate the Hh signaling pathway and targets of this pathway in the limb bud ectoderm. Using immunohistochemistry and various methods of detection for targets of Hh signaling, we found that SHH protein and targets of Hh signaling are present in the limb bud ectoderm including the apex of the bud. To directly test whether ectodermal Hh signaling was required for normal limb patterning, we removed Smo, an essential component of the Hh signaling pathway, from the apical ectodermal ridge (AER). Loss of functional Hh signaling in the AER resulted in disruption of the normal digit pattern and formation of additional postaxial cartilaginous condensations. These data indicate that contrary to previous accounts, the Hh signaling pathway is present and required in the developing limb AER for normal autopod development.

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:26657772

  5. Pro-oxidant status and matrix metalloproteinases in apical lesions and gingival crevicular fluid as potential biomarkers for asymptomatic apical periodontitis and endodontic treatment response

    PubMed Central

    2012-01-01

    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 < 0.05). Total oxidant status correlated positively with matrix metalloproteinase-2 and lesion size (p < 0.05). Gingival crevicular fluid showed significantly lower levels of total antioxidant status in diseased teeth at baseline compared to controls and endodontically-treated groups. Conclusions Apical lesions display an oxidant imbalance along with increased activity of matrix metalloproteinase-2 and -9 and might contribute to

  6. Disruptive innovation: the demand side.

    PubMed

    Havighurst, Clark C

    2008-01-01

    The notion of disruptive innovation provides a welcome framework for considering the prospects for low-cost alternatives in American medicine. Such innovations as have been seen, however, are largely the result of demand by patients paying their own bills because they have high-deductible coverage or are uninsured. Many other cost-saving innovations are discouraged by financing systems that are themselves largely immune to competition from disruptive innovators.

  7. Ballistic Graphene Josephson Junctions from the Short to the Long Junction Regimes

    NASA Astrophysics Data System (ADS)

    Borzenets, I. V.; Amet, F.; Ke, C. T.; Draelos, A. W.; Wei, M. T.; Seredinski, A.; Watanabe, K.; Taniguchi, T.; Bomze, Y.; Yamamoto, M.; Tarucha, S.; Finkelstein, G.

    2016-12-01

    We investigate the critical current IC of ballistic Josephson junctions made of encapsulated graphene-boron-nitride heterostructures. We observe a crossover from the short to the long junction regimes as the length of the device increases. In long ballistic junctions, IC is found to scale as ∝exp (-kBT /δ E ). The extracted energies δ E are independent of the carrier density and proportional to the level spacing of the ballistic cavity. As T →0 the critical current of a long (or short) junction saturates at a level determined by the product of δ E (or Δ ) and the number of the junction's transversal modes.

  8. Slit Diaphragms Contain Tight Junction Proteins

    PubMed Central

    Fukasawa, Hirotaka; Bornheimer, Scott; Kudlicka, Krystyna; Farquhar, Marilyn G.

    2009-01-01

    Slit diaphragms are essential components of the glomerular filtration apparatus, as changes in these junctions are the hallmark of proteinuric diseases. Slit diaphragms, considered specialized adherens junctions, contain both unique membrane proteins (e.g., nephrin, podocin, and Neph1) and typical adherens junction proteins (e.g., P-cadherin, FAT, and catenins). Whether slit diaphragms also contain tight junction proteins is unknown. Here, immunofluorescence, immunogold labeling, and cell fractionation demonstrated that rat slit diaphragms contain the tight junction proteins JAM-A (junctional adhesion molecule A), occludin, and cingulin. We found these proteins in the same protein complexes as nephrin, podocin, CD2AP, ZO-1, and Neph1 by cosedimentation, coimmunoprecipitation, and pull-down assays. PAN nephrosis increased the protein levels of JAM-A, occludin, cingulin, and ZO-1 several-fold in glomeruli and loosened their attachment to the actin cytoskeleton. These data extend current information about the molecular composition of slit diaphragms by demonstrating the presence of tight junction proteins, although slit diaphragms lack the characteristic morphologic features of tight junctions. The contribution of these proteins to the assembly of slit diaphragms and potential signaling cascades requires further investigation. PMID:19478094

  9. Dressed fluxon in a Josephson window junction

    NASA Astrophysics Data System (ADS)

    Caputo, Jean Guy; Flytzanis, Nikos; Devoret, Michel

    1994-09-01

    The static fluxon solutions of a Josephson window junction have been studied numerically. We show that the effect of the idle region surrounding the junction is to ``dress'' the fluxon causing its energy to increase. This effect can be predicted accurately by a simple model.

  10. Analysis of Tight Junction Formation and Integrity

    SciTech Connect

    Karakaya, Mahmut; Kerekes, Ryan A; Morrell-Falvey, Jennifer L; Foster, Carmen M; Retterer, Scott T

    2012-01-01

    In this paper, we study segmentation of tight junctions and analyze the formation and integrity of tight junctions in large-scale confocal image stacks, a challenging biological problem because of the low spatial resolution images and the presence of breaks in tight junction structure. We present an automated, three-step processing approach for tight junction analysis. In our approach, we first localize each individual nucleus in the image by using thresholding, morphological filters and active contours. By using each nucleus position as a seed point, we automatically segment the cell body based on the active contour. We then use an intensity-based skeletonization algorithm to generate the boundary regions for each cell, and features are extracted from tight junctions associated with each cell to assess tight junction continuity. Based on qualitative results and quantitative comparisons, we show that we are able to automatically segment tight junctions and compute relevant features that provide a quantitative measure of tight junction formation to which the permeability of the cell monolayer can ultimately be correlated.

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

    PubMed

    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.

  12. Ezrin: a regulator of actin microfilaments in cell junctions of the rat testis

    PubMed Central

    Gungor-Ordueri, N Ece; Celik-Ozenci, Ciler; Cheng, C Yan

    2015-01-01

    Ezrin, radixin, moesin and merlin (ERM) proteins are highly homologous actin-binding proteins that share extensive sequence similarity with each other. These proteins tether integral membrane proteins and their cytoplasmic peripheral proteins (e.g., adaptors, nonreceptor protein kinases and phosphatases) to the microfilaments of actin-based cytoskeleton. Thus, these proteins are crucial to confer integrity of the apical membrane domain and its associated junctional complex, namely the tight junction and the adherens junction. Since ectoplasmic specialization (ES) is an F-actin-rich testis-specific anchoring junction-a highly dynamic ultrastructure in the seminiferous epithelium due to continuous transport of germ cells, in particular spermatids, across the epithelium during the epithelial cycle-it is conceivable that ERM proteins are playing an active role in these events. Although these proteins were first reported almost 25 years and have since been extensively studied in multiple epithelia/endothelia, few reports are found in the literature to examine their role in the actin filament bundles at the ES. Studies have shown that ezrin is also a constituent protein of the actin-based tunneling nanotubes (TNT) also known as intercellular bridges, which are transient cytoplasmic tubular ultrastructures that transport signals, molecules and even organelles between adjacent and distant cells in an epithelium to coordinate cell events that occur across an epithelium. Herein, we critically evaluate recent data on ERM in light of recent findings in the field in particular ezrin regarding its role in actin dynamics at the ES in the testis, illustrating additional studies are warranted to examine its physiological significance in spermatogenesis. PMID:25652626

  13. Cortisol affects tight junction morphology between pavement cells of rainbow trout gills in single-seeded insert culture.

    PubMed

    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

  14. Zipper and freeway shear zone junctions

    NASA Astrophysics Data System (ADS)

    Passchier, Cees; Platt, John

    2016-04-01

    Ductile shear zones are usually presented as isolated planar high-strain domains in a less deformed wall rock, characterised by shear sense indicators such as characteristic deflected foliation traces. Many shear zones, however, form branched systems and if movement on such branches is contemporaneous, the resulting geometry can be complicated and lead to unusual fabric geometries in the wall rock. For Y-shaped shear zone junctions with three simultaneously operating branches, and with slip directions at a high angle to the branch line, eight basic types of shear zone triple junctions are possible, divided into three groups. The simplest type, called freeway junctions, have similar shear sense on all three branches. If shear sense is different on the three branches, this can lead to space problems. Some of these junctions have shear zone branches that join to form a single branch, named zipper junctions, or a single shear zone which splits to form two, known as wedge junctions. Closing zipper junctions are most unusual, since they form a non-active high-strain zone with opposite deflection of foliations. Shear zipper and shear wedge junctions have two shear zones with similar shear sense, and one with the opposite sense. All categories of shear zone junctions show characteristic flow patterns in the shear zone and its wall rock. Shear zone junctions with slip directions normal to the branch line can easily be studied, since ideal sections of shear sense indicators lie in the plane normal to the shear zone branches and the branch line. Expanding the model to allow slip oblique and parallel to the branch line in a full 3D setting gives rise to a large number of geometries in three main groups. Slip directions can be parallel on all branches but oblique to the branch line: two slip directions can be parallel and a third oblique, or all three branches can have slip in different directions. Such more complex shear zone junctions cannot be studied to advantage in a

  15. Apical Polarity of N-CAM and EMMPRIN in Retinal Pigment Epithelium Resulting from Suppression of Basolateral Signal Recognition

    PubMed Central

    Marmorstein, Alan D.; Gan, Yunbo C.; Bonilha, Vera L.; Finnemann, Silvia C.; Csaky, Karl G.; Rodriguez-Boulan, Enrique

    1998-01-01

    Retinal pigment epithelial (RPE) cells apically polarize proteins that are basolateral in other epithelia. This reversal may be generated by the association of RPE with photoreceptors and the interphotoreceptor matrix, postnatal expansion of the RPE apical surface, and/or changes in RPE sorting machinery. We compared two proteins exhibiting reversed, apical polarities in RPE cells, neural cell adhesion molecule (N-CAM; 140-kD isoform) and extracellular matrix metalloproteinase inducer (EMMPRIN), with the cognate apical marker, p75-neurotrophin receptor (p75-NTR). N-CAM and p75-NTR were apically localized from birth to adulthood, contrasting with a basolateral to apical switch of EMMPRIN in developing postnatal rat RPE. Morphometric analysis demonstrated that this switch cannot be attributed to expansion of the apical surface of maturing RPE because the basolateral membrane expanded proportionally, maintaining a 3:1 apical/basolateral ratio. Kinetic analysis of polarized surface delivery in MDCK and RPE-J cells showed that EMMPRIN has a basolateral signal in its cytoplasmic tail recognized by both cell lines. In contrast, the basolateral signal of N-CAM is recognized by MDCK cells but not RPE-J cells. Deletion of N-CAM's basolateral signal did not prevent its apical localization in vivo. The data demonstrate that the apical polarity of EMMPRIN and N-CAM in mature RPE results from suppressed decoding of specific basolateral signals resulting in randomized delivery to the cell surface. PMID:9700159

  16. Ethanol-induced disruption of Golgi apparatus morphology, primary neurite number and cellular orientation in developing cortical neurons.

    PubMed

    Powrozek, Teresa A; Olson, Eric C

    2012-11-01

    Prenatal ethanol exposure disrupts cortical neurite initiation and outgrowth, but prior studies have reported both ethanol-dependent growth promotion and inhibition. To resolve this ambiguity and better approximate in vivo conditions, we quantitatively analyzed neuronal morphology using a new, whole hemisphere explant model. In this model, Layer 6 (L6) cortical neurons migrate, laminate and extend neurites in an organotypic fashion. To selectively label L6 neurons, we performed ex utero electroporation of a GFP expression construct at embryonic day 13 and allowed the explants to develop for 2 days in vitro. Explants were exposed to (400 mg/dL) ethanol for either 4 or 24 h prior to fixation. Complete 3-D reconstructions were made of >80 GFP-positive neurons in each experimental condition. Acute responses to ethanol exposure included compaction of the Golgi apparatus accompanied by elaboration of supernumerary primary apical neurites, as well as a modest (∼15%) increase in higher order apical neurite length. With longer exposure time, ethanol exposure leads to a consistent, significant disorientation of the cell (cell body, primary apical neurite, and Golgi) with respect to the pial surface. The effects on cellular orientation were accompanied by decreased expression of cytoskeletal elements, microtubule-associated protein 2 and F-actin. These findings indicate that upon exposure to ethanol, developing L6 neurons manifest disruptions in Golgi apparatus and cytoskeletal elements which may in turn trigger selective and significant perturbations to primary neurite formation and neuronal polarity.

  17. Shear zone junctions: Of zippers and freeways

    NASA Astrophysics Data System (ADS)

    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.

  18. Involvement of the helix-loop-helix protein Id-1 in the glucocorticoid regulation of tight junctions in mammary epithelial cells.

    PubMed

    Woo, P L; Cercek, A; Desprez, P Y; Firestone, G L

    2000-09-15

    Mammary epithelial cell-cell junctions undergo morphological and structural differentiation during pregnancy and lactation, but little is known about the transcriptional regulators that are involved in this process. In Con8 mammary epithelial tumor cells, we have previously documented that the synthetic glucocorticoid, dexamethasone, induces the reorganization of the tight junction and adherens junction and stimulates the monolayer transepithelial electrical resistance (TER), a reliable in vitro measurement of tight junction sealing. Western blots demonstrated that dexamethasone treatment rapidly and strongly stimulated the level of the Id-1 protein, which is a serum-inducible helix-loop-helix transcriptional repressor. The steroid induction of Id-1 was robust by 4 h of treatment and maintained over a 24-h period. Isopropyl-1-thio-beta-d-galactopyranoside-inducible expression of exogenous Id-1 in Con8 cells was shown to strongly facilitate the dexamethasone induction of TER in the absence of serum without altering the dexamethasone-dependent reorganization of ZO-1, beta-catenin, or F-actin. Ectopic overexpression of Id-1 in the SCp2 nontumorigenic mammary epithelial cells, which does not undergo complete dexamethasone-dependent tight junction reorganization, enhanced the dexamethasone-induced ZO-1 tight junction localization and stimulated the monolayer TER. Moreover, antisense reduction of Id-1 protein in SCp2 cells prevented the apical junction reorganization and dexamethasone-stimulated TER. Our results implicate Id-1 as acting as a critical regulator of mammary epithelial cell-cell interactions at an early step in the glucocorticoid-dependent signaling pathway that controls tight junction integrity.

  19. Gap junctional communication modulates gene transcription by altering the recruitment of Sp1 and Sp3 to connexin-response elements in osteoblast promoters

    NASA Technical Reports Server (NTRS)

    Stains, Joseph P.; Lecanda, Fernando; Screen, Joanne; Towler, Dwight A.; Civitelli, Roberto

    2003-01-01

    Loss-of-function mutations of gap junction proteins, connexins, represent a mechanism of disease in a variety of tissues. We have shown that recessive (gene deletion) or dominant (connexin45 overexpression) disruption of connexin43 function results in osteoblast dysfunction and abnormal expression of osteoblast genes, including down-regulation of osteocalcin transcription. To elucidate the molecular mechanisms of gap junction-sensitive transcriptional regulation, we systematically analyzed the rat osteocalcin promoter for sensitivity to gap junctional intercellular communication. We identified an Sp1/Sp3 containing complex that assembles on a minimal element in the -70 to -57 region of the osteocalcin promoter in a gap junction-dependent manner. This CT-rich connexin-response element is necessary and sufficient to confer gap junction sensitivity to the osteocalcin proximal promoter. Repression of osteocalcin transcription occurs as a result of displacement of the stimulatory Sp1 by the inhibitory Sp3 on the promoter when gap junctional communication is perturbed. Modulation of Sp1/Sp3 recruitment also occurs on the collagen Ialpha1 promoter and translates into gap junction-sensitive transcriptional control of collagen Ialpha1 gene expression. Thus, regulation of Sp1/Sp3 recruitment to the promoter may represent a potential general mechanism for transcriptional control of target genes by signals passing through gap junctions.

  20. Do Parameters Of Irradiation Influences The Apical Sealing Of Er:YAG Laser Apicetomies?

    NASA Astrophysics Data System (ADS)

    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, p<0.05). There was a significantly difference between the groups. It is concluded that the apicectomies carried out with 400 mJ/6 Hz showed the smallest infiltration value.

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

    PubMed

    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.

  2. Ex vivo accuracy of three electronic apex locators using different apical file sizes.

    PubMed

    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.

  3. Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

    SciTech Connect

    Cleland, A.N.

    1991-04-01

    Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q {approx} 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement.

  4. Assembly of the cochlear gap junction macromolecular complex requires connexin 26.

    PubMed

    Kamiya, Kazusaku; Yum, Sabrina W; Kurebayashi, Nagomi; Muraki, Miho; Ogawa, Kana; Karasawa, Keiko; Miwa, Asuka; Guo, Xueshui; Gotoh, Satoru; Sugitani, Yoshinobu; Yamanaka, Hitomi; Ito-Kawashima, Shioko; Iizuka, Takashi; Sakurai, Takashi; Noda, Tetsuo; Minowa, Osamu; Ikeda, Katsuhisa

    2014-04-01

    Hereditary deafness affects approximately 1 in 2,000 children. Mutations in the gene encoding the cochlear gap junction protein connexin 26 (CX26) cause prelingual, nonsyndromic deafness and are responsible for as many as 50% of hereditary deafness cases in certain populations. Connexin-associated deafness is thought to be the result of defective development of auditory sensory epithelium due to connexion dysfunction. Surprisingly, CX26 deficiency is not compensated for by the closely related connexin CX30, which is abundantly expressed in the same cochlear cells. Here, using two mouse models of CX26-associated deafness, we demonstrate that disruption of the CX26-dependent gap junction plaque (GJP) is the earliest observable change during embryonic development of mice with connexin-associated deafness. Loss of CX26 resulted in a drastic reduction in the GJP area and protein level and was associated with excessive endocytosis with increased expression of caveolin 1 and caveolin 2. Furthermore, expression of deafness-associated CX26 and CX30 in cell culture resulted in visible disruption of GJPs and loss of function. Our results demonstrate that deafness-associated mutations in CX26 induce the macromolecular degradation of large gap junction complexes accompanied by an increase in caveolar structures.

  5. Quantitative cell polarity imaging defines leader-to-follower transitions during collective migration and the key role of microtubule-dependent adherens junction formation.

    PubMed

    Revenu, Céline; Streichan, Sebastian; Donà, Erika; Lecaudey, Virginie; Hufnagel, Lars; Gilmour, Darren

    2014-03-01

    The directed migration of cell collectives drives the formation of complex organ systems. A characteristic feature of many migrating collectives is a 'tissue-scale' polarity, whereby 'leader' cells at the edge of the tissue guide trailing 'followers' that become assembled into polarised epithelial tissues en route. Here, we combine quantitative imaging and perturbation approaches to investigate epithelial cell state transitions during collective migration and organogenesis, using the zebrafish lateral line primordium as an in vivo model. A readout of three-dimensional cell polarity, based on centrosomal-nucleus axes, allows the transition from migrating leaders to assembled followers to be quantitatively resolved for the first time in vivo. Using live reporters and a novel fluorescent protein timer approach, we investigate changes in cell-cell adhesion underlying this transition by monitoring cadherin receptor localisation and stability. This reveals that while cadherin 2 is expressed across the entire tissue, functional apical junctions are first assembled in the transition zone and become progressively more stable across the leader-follower axis of the tissue. Perturbation experiments demonstrate that the formation of these apical adherens junctions requires dynamic microtubules. However, once stabilised, adherens junction maintenance is microtubule independent. Combined, these data identify a mechanism for regulating leader-to-follower transitions within migrating collectives, based on the relocation and stabilisation of cadherins, and reveal a key role for dynamic microtubules in this process.

  6. The plastidial folylpolyglutamate synthetase and root apical meristem maintenance

    PubMed Central

    Srivastava, Avinash C; Tang, Yuhong; Díaz de la Garza, Rocío I

    2011-01-01

    Folylpolyglutamate synthetase (FPGS) catalyzes the attachment of glutamate residues to the folate molecule in plants. Three isoforms of FPGS have been identified in Arabidopsis and these are localized in the plastid (AtDFB), mitochondria (AtDFC) and cytosol (AtDFD). We recently determined that mutants in the AtDFB (At5G05980) gene disrupt primary root development in Arabidopsis thaliana seedlings. Transient expression of AtDFB-green fluorescent protein (GFP) fusion under the control of the native AtDFB promoter in Nicotiana tabacum leaf epidermal cells verified the plastid localization of AtDFB. Furthermore, low concentrations of methotrexate (MTX), a compound commonly used as a folate antagonist in plant and mammalian cells induced primary root defects in wild type seedlings that were similar to atdfb. In addition, atdfb seedlings were more sensitive to MTX when compared to wild type. Quantitative (q) RT-PCR showed lower transcript levels of the mitochondrial and cytosolic FPGS in roots of 7-day-old atdfb seedling suggesting feedback regulation of AtDFB on the expression of other FPGS isoforms during early seedling development. The primary root defects of atdfb, which can be traced in part to altered quiescent center (QC) identity, pave the way for future studies that could link cell type specific folate and FPGS isoform requirements to whole organ development. PMID:21502816

  7. Probiotics ameliorate the hydrogen peroxide-induced epithelial barrier disruption by a PKC- and MAP kinase-dependent mechanism

    PubMed Central

    Seth, A.; Yan, Fang; Polk, D.Brent; Rao, R. K.

    2009-01-01

    Probiotics promote intestinal epithelial integrity and reduce infection and diarrhea. We evaluated the effect of Lactobacillus rhamnosus GG-produced soluble proteins (p40 and p75) on the hydrogen peroxide-induced disruption of tight junctions and barrier function in Caco-2 cell monolayers. Pretreatment of cell monolayers with p40 or p75 attenuated the hydrogen peroxide-induced decrease in transepithelial resistance and increase in inulin permeability in a time- and dose-dependent manner. p40 and p75 also prevented hydrogen peroxide-induced redistribution of occludin, ZO-1, E-cadherin, and β-catenin from the intercellular junctions and their dissociation from the detergent-insoluble fractions. Both p40 and p75 induced a rapid increase in the membrane translocation of PKCβI and PKCε. The attenuation of hydrogen peroxide-induced inulin permeability and redistribution of tight junction proteins by p40 and p75 was abrogated by Ro-32-0432, a PKC inhibitor. p40 and p75 also rapidly increased the levels of phospho-ERK1/2 in the detergent-insoluble fractions. U0126 (a MAP kinase inhibitor) attenuated the p40- and p75-mediated reduction of hydrogen peroxide-induced tight junction disruption and inulin permeability. These studies demonstrate that probiotic-secretory proteins protect the intestinal epithelial tight junctions and the barrier function from hydrogen peroxide-induced insult by a PKC- and MAP kinase-dependent mechanism. PMID:18292183

  8. Probiotics ameliorate the hydrogen peroxide-induced epithelial barrier disruption by a PKC- and MAP kinase-dependent mechanism.

    PubMed

    Seth, A; Yan, Fang; Polk, D Brent; Rao, R K

    2008-04-01

    Probiotics promote intestinal epithelial integrity and reduce infection and diarrhea. We evaluated the effect of Lactobacillus rhamnosus GG-produced soluble proteins (p40 and p75) on the hydrogen peroxide-induced disruption of tight junctions and barrier function in Caco-2 cell monolayers. Pretreatment of cell monolayers with p40 or p75 attenuated the hydrogen peroxide-induced decrease in transepithelial resistance and increase in inulin permeability in a time- and dose-dependent manner. p40 and p75 also prevented hydrogen peroxide-induced redistribution of occludin, ZO-1, E-cadherin, and beta-catenin from the intercellular junctions and their dissociation from the detergent-insoluble fractions. Both p40 and p75 induced a rapid increase in the membrane translocation of PKCbetaI and PKCepsilon. The attenuation of hydrogen peroxide-induced inulin permeability and redistribution of tight junction proteins by p40 and p75 was abrogated by Ro-32-0432, a PKC inhibitor. p40 and p75 also rapidly increased the levels of phospho-ERK1/2 in the detergent-insoluble fractions. U0126 (a MAP kinase inhibitor) attenuated the p40- and p75-mediated reduction of hydrogen peroxide-induced tight junction disruption and inulin permeability. These studies demonstrate that probiotic-secretory proteins protect the intestinal epithelial tight junctions and the barrier function from hydrogen peroxide-induced insult by a PKC- and MAP kinase-dependent mechanism.

  9. Revitalization of open apex teeth with apical periodontitis using a collagen-hydroxyapatite scaffold.

    PubMed

    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.

  10. In vitro evaluation of Root ZX and Raypex 6 in teeth with different apical diameters

    PubMed Central

    Aydin, Ugur; Karataslioglu, Emrah; Aksoy, Fatih; Yildirim, Cihan

    2015-01-01

    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). Intra-group results of Root ZX and Raypex 6 were similar (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. PMID:25657531

  11. Prevalence of occlusal pulpar exposure in 110 equine cheek teeth with apical infections and idiopathic fractures.

    PubMed

    van den Enden, M S D; Dixon, P M

    2008-12-01

    Examination of 110 cheek teeth (CT) that were clinically extracted (between 2004 and 2008) because of apical infection (n=79; mean dental age 3.5 years) or idiopathic CT fractures (n=31; median dental age 8.5 years), including examinations of transverse and longitudinal sections, showed the apical infections to be mainly (68%) due to anachoresis, with the residual cases caused by periodontal spread, infundibular caries spread, fissure fractures and dysplasia. The idiopathic fracture patterns were similar to previously described patterns. Occlusal pulpar exposure was found in 32% of apically infected CT, including multiple pulps in 27% and a single pulp in 5%. However, 10% of apically infected CT had changes to the occlusal secondary dentine, termed occlusal pitting, but did not have exposure of the underlying pulp. Multiple pulpar exposures occurred in some CT with apical infections, and the combination of pulp involvement reflects the anatomical relationships of these pulps. A higher proportion (42%) of CT extracted because idiopathic fractures had pulpar exposure (26% multiple, 16% single pulps), especially with midline sagittal maxillary and miscellaneous pattern mandibular CT fractures, but only (3%) had occlusal pitting.

  12. Cholinergic modulation differs between basal and apical dendritic excitation of hippocampal CA1 pyramidal cells.

    PubMed

    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.

  13. Synaptotagmin-Like Proteins Control Formation of a Single Apical Membrane Domain in Epithelial Cells

    PubMed Central

    Gálvez-Santisteban, Manuel; Rodriguez-Fraticelli, Alejo E.; Bryant, David M.; Vergarajauregui, Silvia; Yasuda, Takao; Bañón-Rodríguez, Inmaculada; Bernascone, Ilenia; Datta, Anirban; Spivak, Natalie; Young, Kitty; Slim, Christiaan L.; Brakeman, Paul R.; Fukuda, Mitsunori; Mostov, Keith E.; Martín-Belmonte, Fernando

    2012-01-01

    SUMMARY The formation of epithelial tissues requires both the generation of apical-basal polarity and the co-ordination of this polarity between neighboring cells to form a central lumen. During de novo lumen formation, vectorial membrane transport contributes to formation of a singular apical membrane, resulting in contribution of each cell to only a single lumen. Here, from a functional screen for genes required for 3D epithelial architecture we identify key roles for Synaptotagmin-like proteins 2-a and 4-a (Slp2-a/4-a) in generation of a single apical surface per cell. Slp2-a localizes to the luminal membrane in a PI(4,5)P2-dependent manner, where it targets Rab27-loaded vesicles to initiate a single lumen. Vesicle tethering and fusion is controlled by Slp4-a, in conjunction with Rab27/Rab3/Rab8 and the SNARE Syntaxin-3. Together, Slp2-a/4-a co-ordinate the spatiotemporal organization of vectorial apical transport to ensure only a single apical surface, and thus formation of a single lumen, occurs per cell. PMID:22820376

  14. Function of BMPs in the apical ectoderm of the developing mouse limb.

    PubMed

    Wang, Chi-Kuang Leo; Omi, Minoru; Ferrari, Deborah; Cheng, Hsu-Chen; Lizarraga, Gail; Chin, Hsian-Jean; Upholt, William B; Dealy, Caroline N; Kosher, Robert A

    2004-05-01

    Several bone morphogenetic proteins (BMPs) are expressed in the apical ectodermal ridge (AER), a critical signaling center that directs the outgrowth and patterning of limb mesoderm, but little is known about their function. To study the functions of apical ectodermal BMPs, an AER-specific promoter element from the Msx2 gene was used to target expression of the potent BMP antagonist noggin to the apical ectoderm of the limbs of transgenic mice. Msx2-noggin mutant mice have severely malformed limbs characterized by syndactyly, postaxial polydactyly, and dorsal transformations of ventral structures indicated by absence of ventral footpads and presence of supernumerary ventral nails. Mutant limb buds exhibit a dorsoventral (DV) and anteroposterior (AP) expansion in the extent of the AER. AER activity persists longer than normal and is maintained in regions of the apical ectoderm where its activity normally ceases. Mutant limbs possess a broad band of mesodermal tissue along the distal periphery that is absent from normal limbs and which fails to undergo the apoptosis that normally occurs in the subectodermal mesoderm. Taken together, our results suggest that apical ectodermal BMPs may delimit the boundaries of the AER by preventing adjacent nonridge ectodermal cells from becoming AER cells; negatively modulate AER activity and thus fine-tune the strength of AER signaling; and regulate the apoptosis of the distal subectodermal mesoderm that occurs as AER activity attenuates, an event that is essential for normal limb development. Our results also confirm that ectodermal BMP signaling regulates DV patterning.

  15. Abnormal apical cell membrane in cystic fibrosis respiratory epithelium. An in vitro electrophysiologic analysis.

    PubMed Central

    Cotton, C U; Stutts, M J; Knowles, M R; Gatzy, J T; Boucher, R C

    1987-01-01

    The transepithelial chloride permeability of airway and sweat ductal epithelium has been reported to be decreased in patients with cystic fibrosis (CF). In the present study, we investigated whether the airway epithelial defect was in the cell path by characterizing the relative ion permeabilities of the apical membrane of respiratory epithelial cells from CF and normal subjects. Membrane electric potential difference (PD) and the responses to luminal Cl- replacement, isoproterenol, and amiloride were measured with intracellular microelectrodes. The PD across the apical barrier was smaller for CF (-11 mV) than normal (-29 mV) epithelia whereas the PD across the basolateral barrier was similar, (-26 and -34 mV respectively). In contrast to normal nasal epithelium, the apical membrane in CF epithelia was not Cl- permselective and was not responsive to isoproterenol. Amiloride, a selective Na+ channel blocker, induced a larger apical membrane hyperpolarization and a greater increase in transepithelial resistance in CF epithelia. Both reduced apical cell membrane Cl- conductance and increased Na+ conductance appear to contribute to the abnormal function of respiratory epithelia of CF patients. PMID:3793933

  16. Local auxin sources orient the apical-basal axis in Arabidopsis embryos.

    PubMed

    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.

  17. Apical extrusion of debris: a literature review of an inherent occurrence during root canal treatment.

    PubMed

    Tanalp, J; Güngör, T

    2014-03-01

    Extrusion of intracanal debris as well as irrigants is a common occurrence during root canal treatment, and no instrument or technique has thoroughly solved this problem. Because flare-ups may arise with any irritation directed towards periapical tissues, a shaping or irrigation technique should minimize the risk of apical extrusion, even though it may not be prevented. There has been a rapid evolution of root canal instruments and irrigation systems through the last decade, and many have been assessed for their debris extrusion potential. The purpose of this review was to identify publications regarding the evaluation of debris, bacteria and irrigant extrusion during root canal treatment. A PubMed, Ovid and MEDLINE search was conducted using the keywords "apical extrusion", "debris extrusion" and "endodontic treatment". The literature search extended over a period of more than 30 years up to 2012. Content of the review was limited to apical extrusion of debris and irrigants, extrusion of liquid by irrigation methods and bacterial extrusion. Issues relevant to apical extrusion were obtained by further search in the reference sections of the retrieved articles. The review provides an update on the current status of apical extrusion.

  18. Online Education Cast as "Disruptive Innovation"

    ERIC Educational Resources Information Center

    Totter, Andrew

    2008-01-01

    Technology-based forces of "disruptive innovation" are gathering around public education and will overhaul the way K-12 students learn--with potentially dramatic consequences for established public schools, according to an upcoming book that draws parallels to disruptions in other industries. In his "Disrupting Class: How Disruptive Innovation…

  19. A New ITPA Disruption Database

    NASA Astrophysics Data System (ADS)

    Hyatt, A. W.; Wesley, J. C.; Strait, E. J.; Schissel, D. P.

    2003-10-01

    A new multi-institutional database of tokamak disruption relevant information is being proposed. Its purpose is to allow a user at any participating institution access to a broad range of disruption and preceding equilibrium data of vetted discharges from each institution. The goal is a common set of data allowing scientific exploration and engineering extrapolation. The data for any given discharge can be in many forms. For example, each discharge may have identifying information (shot number, type of disruption, institution/device, etc.), equilibrium scalar parameters (β, I_p, B_tor, etc.), disruption scalar parameters (max dI/dt, thermal quench time, toroidal asymmetry, etc.), equilibrium radial profile data [j(r), p(r), v_rot(r), etc.], time sequenced data [I(t), β(t), precursor amplitude (t), etc.]. Scalar data will be stored in a SQL format and cross-linked with vector data stored in a MDSPLUS format. Institutions will populate and maintain their own disruption data. Data visualization and analysis tools will be developed. Data available to all is managed by a principal at each institution. Data structure, accessibility and security issues will be discussed, and participation solicited.

  20. Electrostatic control of thermoelectricity in molecular junctions.

    PubMed

    Kim, Youngsang; Jeong, Wonho; Kim, Kyeongtae; Lee, Woochul; Reddy, Pramod

    2014-11-01

    Molecular junctions hold significant promise for efficient and high-power-output thermoelectric energy conversion. Recent experiments have probed the thermoelectric properties of molecular junctions. However, electrostatic control of thermoelectric properties via a gate electrode has not been possible due to technical challenges in creating temperature differentials in three-terminal devices. Here, we show that extremely large temperature gradients (exceeding 1 × 10(9) K m(-1)) can be established in nanoscale gaps bridged by molecules, while simultaneously controlling their electronic structure via a gate electrode. Using this platform, we study prototypical Au-biphenyl-4,4'-dithiol-Au and Au-fullerene-Au junctions to demonstrate that the Seebeck coefficient and the electrical conductance of molecular junctions can be simultaneously increased by electrostatic control. Moreover, from our studies of fullerene junctions, we show that thermoelectric properties can be significantly enhanced when the dominant transport orbital is located close to the chemical potential (Fermi level) of the electrodes. These results illustrate the intimate relationship between the thermoelectric properties and charge transmission characteristics of molecular junctions and should enable systematic exploration of the recent computational predictions that promise extremely efficient thermoelectric energy conversion in molecular junctions.

  1. Plakophilin 3 mediates Rap1-dependent desmosome assembly and adherens junction maturation

    PubMed Central

    Todorovic´, Viktor; Koetsier, Jennifer L.; Godsel, Lisa M.; Green, Kathleen J.

    2014-01-01

    The pathways driving desmosome and adherens junction assembly are temporally and spatially coordinated, but how they are functionally coupled is poorly understood. Here we show that the Armadillo protein plakophilin 3 (Pkp3) mediates both desmosome assembly and E-cadherin maturation through Rap1 GTPase, thus functioning in a manner distinct from the closely related plakophilin 2 (Pkp2). Whereas Pkp2 and Pkp3 share the ability to mediate the initial phase of desmoplakin (DP) accumulation at sites of cell–cell contact, they play distinct roles in later steps: Pkp3 is required for assembly of a cytoplasmic population of DP-enriched junction precursors, whereas Pkp2 is required for transfer of the precursors to the membrane. Moreover, Pkp3 forms a complex with Rap1 GTPase, promoting its activation and facilitating desmosome assembly. We show further that Pkp3 deficiency causes disruption of an E-cadherin/Rap1 complex required for adherens junction sealing. These findings reveal Pkp3 as a coordinator of desmosome and adherens junction assembly and maturation through its functional association with Rap1. PMID:25208567

  2. Hectd1 is required for development of the junctional zone of the placenta.

    PubMed

    Sarkar, Anjali A; Nuwayhid, Samer J; Maynard, Thomas; Ghandchi, Frederick; Hill, Jonathon T; Lamantia, Anthony S; Zohn, Irene E

    2014-08-15

    The placenta plays a critical role in the growth and survival of the fetus. Here we demonstrate that the Homologous to the E6-AP Carboxyl Terminus (HECT) domain E3 ubiquitin ligase, Hectd1, is essential for development of the mouse placenta. Hectd1 is widely expressed during placentation with enrichment in trophoblast giant cells (TGCs) and other trophoblast-derived cell subtypes in the junctional and labyrinth zones of the placenta. Disruption of Hectd1 results in mid-gestation lethality and intrauterine growth restriction (IUGR). Variable defects in the gross structure of the mutant placenta are found including alterations in diameter, thickness and lamination. The number and nuclear size of TGCs is reduced. Examination of subtype specific markers reveals altered TGC development with decreased expression of Placental lactogen-1 and -2 (Pl1 and Pl2) and increased expression of Proliferin (Plf). Reduced numbers of spongiotrophoblasts and glycogen trophoblasts were also found at the junctional zone of the Hectd1 mutant placenta. Finally, there was an increase in immature uterine natural killer (uNK) cells in the maternal decidua of the Hectd1 mutant placenta. Proliferation and apoptosis are differentially altered in the layers of the placenta with an increase in both apoptosis and proliferation in the maternal decidua, a decrease in proliferation and increase in apoptosis in the labyrinth layer and both unchanged in the junctional zone. Together these data demonstrate that Hectd1 is required for development of multiple cell types within the junctional zone of the placenta.

  3. Abnormal endothelial tight junctions in active lesions and normal-appearing white matter in multiple sclerosis.

    PubMed

    Plumb, Jonnie; McQuaid, Stephen; Mirakhur, Meenakshi; Kirk, John

    2002-04-01

    Blood-brain barrier (BBB) breakdown, demonstrable in vivo by enhanced MRI is characteristic of new and expanding inflammatory lesions in relapsing-remitting and chronic progressive multiple sclerosis (MS). Subtle leakage may also occur in primary progressive MS. However, the anatomical route(s) of BBB leakage have not been demonstrated. We investigated the possible involvement of interendothelial tight junctions (TJ) by examining the expression of TJ proteins (occludin and ZO-1 ) in blood vessels in active MS lesions from 8 cases of MS and in normal-appearing white (NAWM) matter from 6 cases. Blood vessels (10-50 per frozen section) were scanned using confocal laser scanning microscopy to acquire datasets for analysis. TJ abnormalities manifested as beading, interruption, absence or diffuse cytoplasmic localization of fluorescence, or separation of junctions (putative opening) were frequent (affecting 40% of vessels) in oil-red-O-positive active plaques but less frequent in NAWM (15%), and in normal (< 2%) and neurological controls (6%). Putatively "open" junctions were seen in vessels in active lesions and in microscopically inflamed vessels in NAWM. Dual fluorescence revealed abnormal TJs in vessels with pre-mortem serum protein leakage. Abnormal or open TJs, associated with inflammation may contribute to BBB leakage in enhancing MRI lesions and may also be involved in subtle leakage in non-enhancing focal and diffuse lesions in NAWM. BBB disruption due to tight junctional pathology should be regarded as a significant form of tissue injury in MS, alongside demyelination and axonopathy.

  4. Molecular mechanism of double Holliday junction dissolution

    PubMed Central

    2014-01-01

    Processing of homologous recombination intermediates is tightly coordinated to ensure that chromosomal integrity is maintained and tumorigenesis avoided. Decatenation of double Holliday junctions, for example, is catalysed by two enzymes that work in tight coordination and belong to the same ‘dissolvasome’ complex. Within the dissolvasome, the RecQ-like BLM helicase provides the translocase function for Holliday junction migration, while the topoisomerase III alpha-RMI1 subcomplex works as a proficient DNA decatenase, together resulting in double-Holliday-junction unlinking. Here, we review the available architectural and biochemical knowledge on the dissolvasome machinery, with a focus on the structural interplay between its components. PMID:25061510

  5. Circuit Theory of Unconventional Superconductor Junctions

    NASA Astrophysics Data System (ADS)

    Tanaka, Y.; Nazarov, Yu. V.; Kashiwaya, S.

    2003-04-01

    We extend the circuit theory of superconductivity to cover transport and proximity effect in mesoscopic systems that contain unconventional superconductor junctions. The approach fully accounts for zero-energy Andreev bound states forming at the surface of unconventional superconductors. As a simple application, we investigate the transport properties of a diffusive normal metal in series with a d-wave superconductor junction. We reveal the competition between the formation of Andreev bound states and proximity effect that depends on the crystal orientation of the junction interface.

  6. Graded junction termination extensions for electronic devices

    NASA Technical Reports Server (NTRS)

    Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

    2006-01-01

    A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

  7. Graded junction termination extensions for electronic devices

    NASA Technical Reports Server (NTRS)

    Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

    2007-01-01

    A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

  8. Tidal disruption of inviscid planetesimals

    NASA Technical Reports Server (NTRS)

    Boss, A. P.; Cameron, A. G. W.; Benz, W.

    1991-01-01

    In view of previous efforts' demonstration that strongly dissipative planetesimals are immune to tidal disruption, an examination is presently conducted of the complementary case of inviscid planetesimals arising from collisions that are sufficiently energetic to entirely melt the resulting planetesimal and debris. The tidal disruption is numerically simulated by means of the smoothed particle hydrodynamics (SPH) code of Cameron and Benz (1991), concentrating on the tidal disruption of 0.01 earth-mass planetesimals passing by the earth with variations in the impact parameter at perigee and velocity at infinity. The SPH models show that tidal forces during a close encounter can efficiently convert orbital angular momentum into spin angular momentum, thereby initiating equatorial mass-shedding to inviscid planetesimals that have been spun up beyond the limit of rotational stability.

  9. Endocrine disrupters and menopausal health.

    PubMed

    Holmes, Philip; Rumsby, Paul; Harrison, Paul T C

    2004-06-01

    Chemicals known to disrupt the endocrine system of animal models are assessed for their potential impact on the health of menopausal and postmenopausal women. These "endocrine disrupters" consist of two groups of compounds - man-made and naturally occurring. There is some evidence to suggest that the naturally occurring phytoestrogens, derived from plant material, may have some beneficial effects on menopausal symptoms and the risk of breast cancer, cardiovascular disease and osteoporosis. Further studies are required to confirm these possibilities. Some man-made environmental pollutants appear to increase the risk of breast cancer, although again the evidence is inconclusive. Mechanistic experiments indicate that these chemicals interact with oestrogen receptors and alter metabolism in a number of different ways, some of which may be important in postmenopausal women. Further investigation of the differences in mode of action between the man-made and the natural endocrine disrupters may lead to important insights into their effects on women's health.

  10. Effect of bovine oviduct epithelial cell apical plasma membranes on sperm function assessed by a novel flow cytometric approach.

    PubMed

    Boilard, Mathieu; Bailey, Janice; Collin, Simon; Dufour, Maurice; Sirard, Marc-André

    2002-10-01

    In the bovine, as in many mammalian species, sperm are temporarily stored in the oviduct before fertilization by binding to the oviduct epithelial cell apical plasma membranes. As the oviduct is able to maintain motility and viability of sperm and modulate capacitation, we propose that proteins present on the apical plasma membrane of oviduct epithelial cells contribute to these effects. To verify this hypothesis, the motility of frozen-thawed sperm was determined after incubation for 6 h with purified apical plasma membranes from fresh or cultured oviduct epithelial cells or from bovine mammary gland cells as a control. Analysis of intracellular calcium levels was performed by flow cytometry on sperm incubated with fresh membranes using Indo-1 to assess the membrane effect on intracellular calcium concentration. The coculture of sperm with fresh and cultured apical membranes maintained initial motility for 6 h (65% and 84%, respectively). This effect was significantly different from control sperm incubated without oviduct epithelial cell apical membranes (23%), with mammary gland cell apical membranes (23%), or with boiled epithelial cell apical membranes (21%). Apical membranes from oviduct epithelial cells diminished the percentage of sperm that reached a lethal calcium concentration over a 4-h period (18.7%) compared with the control (53.8%) and maintained lower intracellular calcium levels in viable sperm. These results show that the apical plasma membrane of bovine oviduct epithelial cells contains anchored proteinic factors that contribute to maintaining motility and viability and possibly to modulating capacitation of bovine sperm.

  11. Diurnal Variation of Tight Junction Integrity Associates Inversely with Matrix Metalloproteinase Expression in Xenopus laevis Corneal Epithelium: Implications for Circadian Regulation of Homeostatic Surface Cell Desquamation

    PubMed Central

    Wiechmann, Allan F.; Ceresa, Brian P.; Howard, Eric W.

    2014-01-01

    Background and Objectives The corneal epithelium provides a protective barrier against pathogen entrance and abrasive forces, largely due to the intercellular junctional complexes between neighboring cells. After a prescribed duration at the corneal surface, tight junctions between squamous surface cells must be disrupted to enable them to desquamate as a component of the tissue homeostatic renewal. We hypothesize that matrix metalloproteinase (MMPs) are secreted by corneal epithelial cells and cleave intercellular junctional proteins extracellularly at the epithelial surface. The purpose of this study was to examine the expression of specific MMPs and tight junction proteins during both the light and dark phases of the circadian cycle, and to assess their temporal and spatial relationships in the Xenopus laevis corneal epithelium. Methodology/Principal Findings Expression of MMP-2, tissue inhibitor of MMP-2 (TIMP-2), membrane type 1-MMP (MT1-MMP) and the tight junction proteins occludin and claudin-4 were examined by confocal double-label immunohistochemistry on corneas obtained from Xenopus frogs at different circadian times. Occludin and claudin-4 expression was generally uniformly intact on the surface corneal epithelial cell lateral membranes during the daytime, but was frequently disrupted in small clusters of cells at night. Concomitantly, MMP-2 expression was often elevated in a mosaic pattern at nighttime and associated with clusters of desquamating surface cells. The MMP-2 binding partners, TIMP-2 and MT1-MMP were also localized to surface corneal epithelial cells during both the light and dark phases, with TIMP-2 tending to be elevated during the daytime. Conclusions/Significance MMP-2 protein expression is elevated in a mosaic pattern in surface corneal epithelial cells during the nighttime in Xenopus laevis, and may play a role in homeostatic surface cell desquamation by disrupting intercellular junctional proteins. The sequence of MMP secretion and

  12. Three-dimensional Organization of Layered Apical Cytoskeletal Networks Associated with Mouse Airway Tissue Development

    PubMed Central

    Tateishi, Kazuhiro; Nishida, Tomoki; Inoue, Kanako; Tsukita, Sachiko

    2017-01-01

    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. PMID:28272499

  13. Apical and basal membrane ion transport mechanisms in bovine retinal pigment epithelium.

    PubMed Central

    Joseph, D P; Miller, S S

    1991-01-01

    1. Intracellular voltage recordings using conventional and double-barrelled chloride-selective microelectrodes have been used to identify several transport mechanisms at the apical and basolateral membranes of the isolated bovine retinal pigment epithelium (RPE)-choroid preparation. Intracellular recordings were obtained from two cell populations, melanotic (pigmented) and amelanotic (non-pigmented). The electrical properties of these two populations are practically identical. For melanotic cells the average apical resting membrane potential (VA) is -61 +/- 2 mV (mean +/- S.E.M., n = 49 cells, thirty-three eyes). For these cells the ratio of apical to basolateral membrane resistance (a) was 0.22 +/- 0.02. The mean transepithelial voltage and resistance were 6 +/- 1 mV and 138 +/- 7 omega cm2, respectively. 2. The apical membrane, which faces the distal retina, contains a Ba(2+)-inhibitable K+ conductance and a ouabain-inhibitable, electrogenic Na(+)-K+ pump. In addition it contains a bumetanide-sensitive mechanism, the putative Na(+)-K(+)-Cl- cotransporter. The basolateral membrane contains a DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonic acid)-inhibitable chloride channel. The relative conductances of the apical and basolateral membranes to K+ and Cl- are TK approximately 0.9 and TCl approximately 0.7, respectively. 3. The ouabain-induced fast phase of apical membrane depolarization (0-30 s) was used to calculate the equivalent resistances of the apical (RA) and basolateral (RB) cell membranes, as well as the paracellular or shunt resistance (RS). They are: 3190 +/- 400, 17920 +/- 2730 and 2550 +/- 200 omega (mean +/- S.E.M., n = 9 tissues), respectively. From these data the equivalent electromotive forces (EMF) at the apical (EA) and basolateral (EB) membranes were also calculated. They are: -69 +/- 5.0 and -24 +/- 5.0 mV, respectively. 4. Intracellular Cl- activity (aiCl) was measured using double-barreled ion-selective microelectrodes. In the steady state

  14. Analyses of Interactions Between Heparin and the Apical Surface Proteins of Plasmodium falciparum

    NASA Astrophysics Data System (ADS)

    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.

  15. Isolated Left Ventricular Apical Hypoplasia with Right Ventricular Outflow Tract Obstruction: A Rare Combination.

    PubMed

    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.

  16. A comparison of apical sealing and extrusion between Thermafil and lateral condensation techniques.

    PubMed

    Abarca, A M; Bustos, A; Navia, M

    2001-11-01

    Forty curved canals from 20 mesial roots of extracted human mandibular molars were instrumented (Profile .04) using a crown-down technique and divided into two groups. The experimental group was obturated using the Thermafil technique and the control group was obturated using the lateral condensation technique. Topseal sealer was used in both groups. Apical extrusion was recorded. Two molars were used as control teeth. All specimens were stored in 100% humidity for 1 wk, coated with nail polish, except for the apical 2 mm, and were suspended in black India ink for 48 h. Molars were decalcified, rendered transparent, and linear dye penetration was measured. Linear dye leakage and apical extrusion between the techniques were not statistically different (Mann-Whitney U test).

  17. Three-dimensional Organization of Layered Apical Cytoskeletal Networks Associated with Mouse Airway Tissue Development

    NASA Astrophysics Data System (ADS)

    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.

  18. An evaluation of the effect of methylene blue dye pH on apical leakage.

    PubMed

    Starkey, D L; Anderson, R W; Pashley, D H

    1993-09-01

    The effect of varying the pH of 2% methylene blue dye on apical leakage was evaluated. Eighty-four roots of extracted human teeth were used in this study. The roots were endodontically cleaned and shaped, obturated, apically resected, and amalgam or Temporary Endodontic Restorative Material retro-fillings were placed. The roots were immersed for 7 days in dye solutions of controlled pH of 1, 2, 3, 5 or 7, or in a 2% unbuffered deionized water solution of methylene blue. The results demonstrated significantly less leakage in the pH 1 and 2 amalgam groups. All other amalgam groups and the Temporary Endodontic Restorative Material groups showed no significant differences attributable to pH. Temporary Endodontic Restorative Material retrofilling groups demonstrated statistically significantly less apical leakage at each pH evaluated than the amalgam-retrofilled groups. Additionally, a significant buffering effect of the root structure on the dye solutions was measured.

  19. Tidal disruption of dissipative planetesimals

    NASA Technical Reports Server (NTRS)

    Mizuno, H.; Boss, A. P.

    1985-01-01

    A self-consistent numerical model is developed for the tidal disruption of a solid planetesimal. The planetesimal is treated as a highly viscous, slightly compressible fluid whose disturbed parts are an inviscid, pressureless fluid undergoing distortion and disruption. The distortions were constrained to being symmetrical above and below the equatorial plane. The tidal potential is expanded in terms of Legendre polynomials, which eliminates the center of mass acceleration effects, permitting definition of equations of motion in a noninertial frame. Consideration is given to viscous dissipation and to characteristics of the solid-atmosphere boundary. The model is applied to sample cases in one, two and three dimensions.

  20. Tidal disruption of viscous bodies

    NASA Technical Reports Server (NTRS)

    Sridhar, S.; Tremaine, S.

    1992-01-01

    Tidal disruptions are investigated in viscous-fluid planetesimals whose radius is small relative to the distance of closest (parabolic-orbit) approach to a planet. The planetesimal surface is in these conditions always ellipsoidal, facilitating treatment by coupled ODEs which are solvable with high accuracy. While the disrupted planetesimals evolve into needlelike ellipsoids, their density does not decrease. The validity of viscous fluid treatment holds for solid (ice or rock) planetesimals in cases where tidal stresses are greater than material strength, but integrity is maintained by self-gravity.

  1. The effect of an Nd-YAG pulsed laser on the cleaning of the root canal and the formation of a fused apical plug.

    PubMed

    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 (P<0.05). A further 20 teeth were not prepared and lased in the coronal one-third of the root canal at different energy levels; five teeth were not lased. The teeth were split and examined as previously. The results showed that lasing cleaned the coronal part of the root canal almost completely of pulpal tissue. In the final part of the study laser 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.

  2. The junctional adhesion molecule JAM-C regulates polarized transendothelial migration of neutrophils in vivo.

    PubMed

    Woodfin, Abigail; Voisin, Mathieu-Benoit; Beyrau, Martina; Colom, Bartomeu; Caille, Dorothée; Diapouli, Frantzeska-Maria; Nash, Gerard B; Chavakis, Triantafyllos; Albelda, Steven M; Rainger, G Ed; Meda, Paolo; Imhof, Beat A; Nourshargh, Sussan

    2011-06-26

    The migration of neutrophils into inflamed tissues is a fundamental component of innate immunity. A decisive step in this process is the polarized migration of blood neutrophils through endothelial cells (ECs) lining the venular lumen (transendothelial migration (TEM)) in a luminal-to-abluminal direction. By real-time confocal imaging, we found that neutrophils had disrupted polarized TEM ('hesitant' and 'reverse') in vivo. We noted these events in inflammation after ischemia-reperfusion injury, characterized by lower expression of junctional adhesion molecule C (JAM-C) at EC junctions, and they were enhanced by blockade or genetic deletion of JAM-C in ECs. Our results identify JAM-C as a key regulator of polarized neutrophil TEM in vivo and suggest that reverse TEM of neutrophils can contribute to the dissemination of systemic inflammation.

  3. Surgical Outcomes and Safety of Robotic Sacrocolpopexy in Women With Apical Pelvic Organ Prolapse

    PubMed Central

    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

  4. Cytokinin is required for escape but not release from auxin mediated apical dominance

    PubMed Central

    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

  5. Vasopressin induces apical expression of caveolin in rat kidney collecting duct principal cells

    PubMed Central

    Lu, Hua A. J.; Russo, Leileata M.; Pastor-Soler, Núria M.; McKee, Mary; McLaughlin, Margaret M.; Bartlett, Bianca E.; Breton, Sylvie; Brown, Dennis

    2013-01-01

    Caveolin (Cav)1 is expressed in the basolateral membrane domain of renal collecting duct (CD) principal cells (PCs), where it is associated with caveolae. To reveal any potential involvement of Cav1 in vasopressin signaling, we used specific monoclonal and polyclonal antibodies to examine its localization in CD PCs of Brattleboro (BB) rats treated with vasopressin (DDAVP). Compared with controls, immunofluorescence revealed a time-dependent increase in Cav1 expression in the