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Sample records for adhesion protein-1 vap-1

  1. The oxidase activity of vascular adhesion protein-1 (VAP-1) is essential for function.

    PubMed

    Noonan, Thomas; Lukas, Susan; Peet, Gregory W; Pelletier, Josephine; Panzenbeck, Mark; Hanidu, Adedayo; Mazurek, Suzanne; Wasti, Ruby; Rybina, Irina; Roma, Teresa; Kronkaitis, Anthony; Shoultz, Alycia; Souza, Donald; Jiang, Huiping; Nabozny, Gerald; Modis, Louise Kelly

    2013-01-01

    Vascular adhesion protein-1 (VAP-1) has been implicated in the pathogenesis of inflammatory diseases and is suggested to play a role in immune cell trafficking. It is not clear whether this effect is mediated by the oxidase activity or by other features of the protein such as direct adhesion. In order to study the role of VAP-1 oxidase activity in vivo, we have generated mice carrying an oxidase activity-null VAP-1 protein. We demonstrate that the VAP-1 oxidase null mutant mice have a phenotype similar to the VAP-1 null mice in animal models of sterile peritonitis and antibody induced arthritis suggesting that the oxidase activity is responsible for the inflammatory function of VAP-1.

  2. Localization of Vascular Adhesion Protein-1 (VAP-1) in the Human Eye

    PubMed Central

    Almulki, Lama; Noda, Kousuke; Nakao, Shintaro; Hisatomi, Toshio; Thomas, Kennard L.; Hafezi-Moghadam, Ali

    2009-01-01

    Recently we showed a critical role for Vascular Adhesion Protein-1 (VAP-1) in rodents during acute ocular inflammation, angiogenesis, and diabetic retinal leukostasis. However, the expression of VAP-1 in the human eye is unknown. VAP-1 localization was investigated by immunohistochemistry. Five μm thick sections were generated from human ocular tissues embedded in paraffin. Sections were incubated overnight with primary mAbs against VAP-1 (5μg/ml), smooth muscle actin (1μg/ml), CD31 or isotype-matched IgG at 4°C. Subsequently, a secondary mAb was used for 30min at room temperature, followed by Dako Envision + HRP (AEC) System for signal detection. The stained sections were examined using light microscopy and the signal intensity was quantified by two masked evaluators and graded into 4 discrete categories. In all examined ocular tissues, VAP-1 staining was confined to the vasculature. VAP-1 labeling showed the highest intensity in both arteries and veins of neuronal tissues; retina, and optic nerve, and the lowest intensity in the iris vasculature (p<0.05). Scleral and choroidal vessels showed moderate staining for VAP-1. VAP-1 intensity was significantly higher in the arteries compared to veins (p<0.05). Furthermore, VAP-1 staining in arteries co-localized with both CD31 and smooth muscle actin (sm-actin) staining, suggesting expression of VAP-1 in endothelial cells, smooth muscle cells or potentially pericytes. In conclusion, Immunohistochemistry reveals constitutive expression of VAP-1 in human ocular tissues. VAP-1 expression is exclusive to the vasculature with arteries showing significantly higher expression than veins. Furthermore, VAP-1 expression in the ocular vasculature is heterogeneous, with the vessels of the optic nerve and the retina showing highest expressions. These results characterize VAP-1 expression in human ocular tissues. PMID:19761765

  3. Novel pyridazinone inhibitors for vascular adhesion protein-1 (VAP-1): old target-new inhibition mode.

    PubMed

    Bligt-Lindén, Eva; Pihlavisto, Marjo; Szatmári, István; Otwinowski, Zbyszek; Smith, David J; Lázár, László; Fülöp, Ferenc; Salminen, Tiina A

    2013-12-27

    Vascular adhesion protein-1 (VAP-1) is a primary amine oxidase and a drug target for inflammatory and vascular diseases. Despite extensive attempts to develop potent, specific, and reversible inhibitors of its enzyme activity, the task has proven challenging. Here we report the synthesis, inhibitory activity, and molecular binding mode of novel pyridazinone inhibitors, which show specificity for VAP-1 over monoamine and diamine oxidases. The crystal structures of three inhibitor-VAP-1 complexes show that these compounds bind reversibly into a unique binding site in the active site channel. Although they are good inhibitors of human VAP-1, they do not inhibit rodent VAP-1 well. To investigate this further, we used homology modeling and structural comparison to identify amino acid differences, which explain the species-specific binding properties. Our results prove the potency and specificity of these new inhibitors, and the detailed characterization of their binding mode is of importance for further development of VAP-1 inhibitors.

  4. Lymphocyte binding to vascular endothelium in inflamed skin revisited: a central role for vascular adhesion protein-1 (VAP-1).

    PubMed

    Arvilommi, A M; Salmi, M; Kalimo, K; Jalkanen, S

    1996-04-01

    The binding of leukocytes to vascular endothelium and their migration into tissues is mediated by adhesion molecules on the endothelial cells and leukocytes. Vascular adhesion protein-1 (VAP-1) is a 170-180/90-kDa endothelial molecule expressed most prominently in high endothelial venules in peripheral lymph node (PLN) type lymphatic tissues. VAP-1 mediates lymphocyte binding to PLN, tonsil and synovium. The expression of VAP-1 is induced in inflammatory diseases such as arthritis and gut inflammation. We examined the expression, structure and function of VAP-1 in normal and inflamed skin and compared it to those of other adhesion molecules implicated in skin homing. In psoriasis lichen ruber planus, pemphigoid and allergic lesions, VAP-1 was markedly upregulated. The expression of VAP-1 was also increased in biopsies of healthy skin of the patients. The VAP-1 molecule induced in skin is decorated with abundant sialic acids. VAP-1 inflamed skin is functional, since inhibition with anti-VAP-1 monoclonal antibodies caused a 60% reduction in lymphocytes adhesion to vascular endothelium. Antibodies against E-selectin, which has been regarded as the major vascular addressin directing cutaneous lymphocyte traffic, and, surprisingly, against peripheral lymph node addressin (PNAd), caused inhibitions of 30% and 60%, respectively, in the frozen section adhesion assay. These findings suggest important roles also for VAP-1 and PNAd in lymphocyte homing into inflamed skin. PMID:8625974

  5. Synthesis and SAR study of new thiazole derivatives as vascular adhesion protein-1 (VAP-1) inhibitors for the treatment of diabetic macular edema: part 2.

    PubMed

    Inoue, Takayuki; Morita, Masataka; Tojo, Takashi; Nagashima, Akira; Moritomo, Ayako; Imai, Keisuke; Miyake, Hiroshi

    2013-05-01

    Novel thiazole derivatives were synthesized and evaluated as vascular adhesion protein-1 (VAP-1) inhibitors. Although our previous compound 1 showed potent VAP-1 inhibitory activity, the activity differed between humans and rats. This issue was overcome by a hybrid design using human VAP-1 specific inhibitor 2, which was found by high-throughput screening (HTS), a docking study of a human VAP-1 homology model, and an analysis of sequence information for humans and rats. As a result, we identified compound 35c, which showed strong VAP-1 inhibitory activity (human IC(50) of 20 nM; rat IC(50) of 72 nM) and significant inhibitory effects in the ex vivo test.

  6. Novel 1H-imidazol-2-amine derivatives as potent and orally active vascular adhesion protein-1 (VAP-1) inhibitors for diabetic macular edema treatment.

    PubMed

    Inoue, Takayuki; Morita, Masataka; Tojo, Takashi; Nagashima, Akira; Moritomo, Ayako; Miyake, Hiroshi

    2013-07-01

    Novel thiazole derivatives were synthesized and evaluated as vascular adhesion protein-1 (VAP-1) inhibitors. Although we previously identified a compound (2) with potent VAP-1 inhibitory activity in rats, the human activity was relatively weak. Here, to improve the human VAP-1 inhibitory activity of compound 2, we first evaluated the structure-activity relationships of guanidine bioisosteres as simple small molecules and identified a 1H-benzimidazol-2-amine (5) with potent activity compared to phenylguanidine (1). Based on the structure of compound 5, we synthesized a highly potent VAP-1 inhibitor (37b; human IC50=0.019 μM, rat IC50=0.0051 μM). Orally administered compound 37b also markedly inhibited ocular permeability in streptozotocin-induced diabetic rats after oral administration, suggesting it is a promising compound for the treatment of diabetic macular edema.

  7. In Vivo Detection of Vascular Adhesion Protein-1 in Experimental Inflammation

    PubMed Central

    Jaakkola, Kimmo; Nikula, Tuomo; Holopainen, Riikka; Vähäsilta, Tommi; Matikainen, Marja-Terttu; Laukkanen, Marja-Leena; Huupponen, Risto; Halkola, Lauri; Nieminen, Lauri; Hiltunen, Jukka; Parviainen, Sakari; Clark, Michael R.; Knuuti, Juhani; Savunen, Timo; Kääpä, Pekka; Voipio-Pulkki, Liisa Maria; Jalkanen, Sirpa

    2000-01-01

    Vascular adhesion protein-1 (VAP-1) is an inflammation-inducible endothelial glycoprotein which mediates leukocyte-endothelial cell interactions. To study the pathogenetic significance of VAP-1 in inflammatory disorders, an in vivo immunodetection method was used to detect the regulation of luminally expressed VAP-1 in experimental skin and joint inflammation in the pig and dog. Moreover, VAP-1 was studied as a potential target to localize inflammation by radioimmunoscintigraphy. Up-regulation of VAP-1 in experimental dermatitis and arthritis could be visualized by specifically targeted immunoscintigraphy. Moreover, the translocation of VAP-1 to the functional position on the endothelial surface was only seen in inflamed tissues. These results suggest that VAP-1 is both an optimal candidate for anti-adhesive therapy and a potential target molecule for imaging inflammation. PMID:10934150

  8. Vascular adhesion protein-1 promotes liver inflammation and drives hepatic fibrosis

    PubMed Central

    Weston, Chris J.; Shepherd, Emma L.; Claridge, Lee C.; Rantakari, Pia; Curbishley, Stuart M.; Tomlinson, Jeremy W.; Hubscher, Stefan G.; Reynolds, Gary M.; Aalto, Kristiina; Anstee, Quentin M.; Jalkanen, Sirpa; Salmi, Marko; Smith, David J.; Day, Christopher P.; Adams, David H.

    2014-01-01

    Nonalcoholic fatty liver disease (NAFLD) encompasses a range of manifestations, including steatosis and cirrhosis. Progressive disease is characterized by hepatic leukocyte accumulation in the form of steatohepatitis. The adhesion molecule vascular adhesion protein-1 (VAP-1) is a membrane-bound amine oxidase that promotes leukocyte recruitment to the liver, and the soluble form (sVAP-1) accounts for most circulating monoamine oxidase activity, has insulin-like effects, and can initiate oxidative stress. Here, we determined that hepatic VAP-1 expression is increased in patients with chronic liver disease and that serum sVAP-1 levels are elevated in patients with NAFLD compared with those in control individuals. In 4 murine hepatic injury models, an absence or blockade of functional VAP-1 reduced inflammatory cell recruitment to the liver and attenuated fibrosis. Moreover, disease was reduced in animals expressing a catalytically inactive form of VAP-1, implicating enzyme activity in the disease pathogenesis. Within the liver, hepatic stromal cells expressed functional VAP-1, and evaluation of cultured cells revealed that sVAP-1 promotes leukocyte migration through catalytic generation of ROS, which depended on VAP-1 enzyme activity. VAP-1 enhanced stromal cell spreading and wound closure and modulated expression of profibrotic genes. Together, these results link the amine oxidase activity of VAP-1 with hepatic inflammation and fibrosis and suggest that targeting VAP-1 has therapeutic potential for NAFLD and other chronic fibrotic liver diseases. PMID:25562318

  9. Organ-selective regulation of vascular adhesion protein-1 expression in man.

    PubMed

    Arvilommi, A M; Salmi, M; Jalkanen, S

    1997-07-01

    Vascular adhesion protein-1 (VAP-1) is an endothelial molecule which mediates lymphocyte binding to endothelium in peripheral lymph nodes and at certain sites of inflammation. The expression of VAP-1 in vivo is strongly up-regulated in inflamed tissues, such as gut and skin. The purpose of this work was to examine the factors responsible for this induction of VAP-1. Since the expression of VAP-1 could not be induced in cultured endothelial cells with a large panel of mediators, we used an organ culture technique for the investigation of the regulation of VAP-1 expression in a more physiological micromilieu. Indeed, we found that the expression of endothelial VAP-1 could be up-regulated in human tonsillar tissue with interleukin (IL)-1, IL-4, tumor necrosis factor (TNF-alpha), interferon (IFN)-gamma and lipopolysaccharide, whereas histamine, thrombin, dibutyryl cAMP, N-formyl-Met-Leu-Phe (fMLP) and phorbol 12-myristate 13-acetate (PMA) had no effect. The induced VAP-1 protein was similar in molecular weight to the non-induced VAP-1, suggesting that VAP-1 synthesized de novo carries appropriate carbohydrate moieties. In contrast to tonsil organ culture, similar inductions performed with human appendix showed no up-regulation of VAP-1 expression, indicating that the regulation of VAP-1 expression exhibits organ-selective characteristics. Furthermore, in these tissues the smooth muscle cells, which constitutively express VAP-1, could not be stimulated to alter their level of expression of this molecule. In conclusion, the expression of VAP-1 can be markedly up-regulated with several mediators in tonsil but not in appendix organ culture, whereas cultured endothelial cells cannot be induced to express VAP-1. These results indicate that the expression of VAP-1 is regulated in a tissue- and cell type-selective manner, and a correct micromilieu is required for the up-regulation to occur. PMID:9247594

  10. Evaluation of Serum Vascular Adhesion Protein-1 as a Potential Biomarker in Thyroid Cancer

    PubMed Central

    Zhao, Pengxin; Zhang, Kaili

    2016-01-01

    Vascular adhesion protein-1 (VAP-1) is a glycoprotein that mediates tissue-selective lymphocyte adhesion. The prognostic value of VAP-1 has been determined in gastric cancer. The aim of this study was to evaluate the changes and the predictive value of serum VAP-1 in patients with thyroid cancer. A total of 126 patients with thyroid nodules and 53 healthy controls participated in this study. The patients were further divided into subgroup 1 (69 cases with benign thyroid nodules) and subgroup 2 (57 cases with thyroid cancer). Serum VAP-1 was measured by time-resolved immunofluorometric assay. Diagnostic value of presurgical VAP-1 for thyroid cancer was conducted by receiver operating characteristic (ROC) curves. Serum levels of VAP-1 were significantly lower in thyroid cancer group than in healthy control and benign thyroid nodule groups. VAP-1 concentrations negatively correlated with serum thyroglobulin (Tg) levels in thyroid cancer patients (r = −0.81; p < 0.001). The optimum cut-off value of VAP-1 was 456.6 ng/mL with a 77.4% specificity and 66.7% sensitivity for thyroid cancer diagnosis. Serum VAP-1 decreased in thyroid cancer patients and VAP-1 could be a potential useful adjunct biomarker in the diagnosis of thyroid cancer. PMID:27446209

  11. Leukocyte trafficking-associated vascular adhesion protein 1 is expressed and functionally active in atherosclerotic plaques

    PubMed Central

    Silvola, Johanna M. U.; Virtanen, Helena; Siitonen, Riikka; Hellberg, Sanna; Liljenbäck, Heidi; Metsälä, Olli; Ståhle, Mia; Saanijoki, Tiina; Käkelä, Meeri; Hakovirta, Harri; Ylä-Herttuala, Seppo; Saukko, Pekka; Jauhiainen, Matti; Veres, Tibor Z.; Jalkanen, Sirpa; Knuuti, Juhani; Saraste, Antti; Roivainen, Anne

    2016-01-01

    Given the important role of inflammation and the potential association of the leukocyte trafficking-associated adhesion molecule vascular adhesion protein 1 (VAP-1) with atherosclerosis, this study examined whether functional VAP-1 is expressed in atherosclerotic lesions and, if so, whether it could be targeted by positron emission tomography (PET). First, immunohistochemistry revealed that VAP-1 localized to endothelial cells of intra-plaque neovessels in human carotid endarterectomy samples from patients with recent ischemic symptoms. In low-density lipoprotein receptor-deficient mice expressing only apolipoprotein B100 (LDLR−/−ApoB100/100), VAP-1 was expressed on endothelial cells lining inflamed atherosclerotic lesions; normal vessel walls in aortas of C57BL/6N control mice were VAP-1-negative. Second, we discovered that the focal uptake of VAP-1 targeting sialic acid-binding immunoglobulin-like lectin 9 based PET tracer [68Ga]DOTA-Siglec-9 in atherosclerotic plaques was associated with the density of activated macrophages (r = 0.58, P = 0.022). As a final point, we found that the inhibition of VAP-1 activity with small molecule LJP1586 decreased the density of macrophages in inflamed atherosclerotic plaques in mice. Our results suggest for the first time VAP-1 as a potential imaging target for inflamed atherosclerotic plaques, and corroborate VAP-1 inhibition as a therapeutic approach in the treatment of atherosclerosis. PMID:27731409

  12. Overexpression of vascular adhesion protein-1 is associated with poor prognosis of astrocytomas.

    PubMed

    Kostoro, Joanna; Chang, Shu-Jyuan; Clark Lai, Yen-Chang; Wu, Chun-Chieh; Chai, Chee-Yin; Kwan, Aij-Lie

    2016-06-01

    Vascular adhesion protein-1 (VAP-1) is one of the endothelial adhesion molecules that is believed to play a role in tumor progression and metastasis, supporting cancer cell extravasation. Very few studies have been performed on analyzing the contribution of VAP-1 in brain tumor. Astrocytomas are the most common type of brain tumors, which are classified by World Health Organization (WHO) into four grades according to the degree of malignancy. This study was designed to investigate VAP-1 expression level in different astrocytoma grades and its correlation with clinicopathological features as well as prognosis of astrocytoma patients. Eighty-seven patients with different grades of astrocytoma (WHO Grade I-Grade IV) were enrolled in this study. The expression of VAP-1 was assayed by immunohistochemistry. The correlation between VAP-1 expression and clinicopathological features was evaluated by Chi-square test, and overall survival was analyzed by Kaplan-Meier method. Cox regression analysis was applied to analyze the independent influence of each parameter on overall survival. The expression level of VAP-1 was significantly higher in diffuse astrocytoma than those of pilocytic astrocytoma (p < 0.0001). In the subgroup analysis, upregulated VAP-1 expression was frequently found in older age patients (≥50 years). The VAP-1 expression was found to be significantly correlated with the overall survival (p = 0.0002). There was a statistical correlation between VAP-1(high) tumors in diffuse astrocytoma and VAP-1(low) tumors in pilocytic astrocytoma (p < 0.0001). Multivariate Cox analysis indicated VAP-1 was an independent predictive marker for poorer prognosis (p = 0.0036). Therefore, VAP-1 could be a promising prognostic biomarker in astrocytoma.

  13. Blockade of Vascular Adhesion Protein-1 Inhibits Lymphocyte Infiltration in Rat Liver Allograft Rejection

    PubMed Central

    Martelius, Timi; Salaspuro, Ville; Salmi, Marko; Krogerus, Leena; Höckerstedt, Krister; Jalkanen, Sirpa; Lautenschlager, Irmeli

    2004-01-01

    Vascular adhesion protein-1 (VAP-1) has been shown to mediate lymphocyte adhesion to endothelia at sites of inflammation, but its functional role in vivo has not been tested in any rodent model. Here we report the effects of VAP-1 blockade on rat liver allograft rejection. BN recipients of PVG liver allografts (known to develop acute rejection by day 7) were treated with 2 mg/kg anti-VAP-1 (a new anti-rat VAP-1 mAb 174–5) or isotype-matched irrelevant antibody (NS1) every other day (n = 6/group) and one group with anti-VAP-1 2 mg/kg daily (n = 7). On day 7, samples were collected for transplant aspiration cytology, histology, and immunohistochemistry. Lymphocyte infiltration to the graft was clearly affected by VAP-blockade. The total inflammation, mainly the number of active lymphoid cells, in transplant aspiration cytology was significantly decreased in animals treated with anti-VAP-1 (4.7 ± 1.0 and 2.4 ± 1.0 corrected increment units, respectively) compared to control (6.6 ± 1.0) (P < 0.05). In histology, the intensity of portal inflammation was significantly decreased (P < 0.05). The amount of T cells expressing activation markers diminished. This is the first demonstration in any prolonged in vivo model that VAP-1 plays an important role in lymphocyte infiltration to sites of inflammation, and, in particular, liver allograft rejection. PMID:15579442

  14. VAP-1 in peritoneally dialyzed patients.

    PubMed

    Koc-Zorawska, Ewa; Malyszko, Jolanta; Zbroch, Edyta; Malyszko, Jacek; Mysliwiec, Michal

    2013-01-01

    VAP-1 (vascular adhesion protein-1) possesses semicarbazide-sensitive amine oxidase (SSAO) activity. It has also been found that serum VAP-1 was elevated in acute and chronic hyperglycemia and in patients with diabetes as well as in chronic kidney disease. Renalase, with possible monoamine oxidase activity, which breaks down catecholamines such as SSAO, is expressed in the endothelium as well as in the kidney. The aim of the study was to assess serum VAP-1 levels in peritoneally dialyzed (PD) patients and factors explaining its variability. This pilot study was performed on 25 peritoneally dialyzed patients, including 4 patients with type 2 diabetes. We found that the mean VAP-1 was significantly higher in chronic ambulatory peritoneal dialysis (CAPD) patients when compared to the control group (p<0.05). Dopamine was significantly lower in PD patients when compared to the healthy volunteers (p<0.05), whereas noradrenaline was significantly higher in PD patients relative to the healthy volunteers (p<0.01). There was a significant difference in the VAP-1 concentration in the group with and without residual renal function (p<0.05) as well as between 10 patients with hyperglycemia when compared to patients with normoglycemia (p<0.05). There was no effect of gender on the serum VAP-1 levels. In PD patients VAP-1 correlated with systolic blood pressure (r=-0.4, p<005), residual renal function (r=-0.62, p<0.05), and glucose (=0.54, p<0.05). We concluded that VAP-1, elevated in patients on PD, was predominantly dependent on residual kidney function and glucose level, factors both linked to endothelial damage and cardiovascular complications.

  15. Circulating renalase, catecholamines, and vascular adhesion protein 1 in hypertensive patients.

    PubMed

    Maciorkowska, Dominika; Zbroch, Edyta; Malyszko, Jolanta

    2015-11-01

    The aim of the study was to estimate and correlate circulating levels of renalase, vascular adhesion protein-1 (VAP-1), catecholamines in patients with primary hypertension. The renalase, VAP-1, and catecholamines concentration was estimated in 121 hypertensive patients. The correlation between renalase, VAP-1 levels and catecholamine concentration in blood, blood pressure control, pharmacological therapy, and medical history were taken in to consideration. The median office blood pressure was 145.5/86 mm Hg and was significantly higher than the median home blood pressure measurement value, which was 135/80 mm Hg, P < .05. Circulating renalase and VAP-1 (Me 9.57 μg/mL and Me = 326.7 ng/mL) levels were significantly higher in patients with hypertension comparing to healthy individuals (3.83 μg/mL and 248.37 ng/mL, P < .05). The correlation between renalase and noradrenalin concentration in blood was observed (r = 0.549; P < .05), also the correlation between VAP-1 and noradrenaline was noticed (r = 0.21, P = .029). Renalase level was higher in patients with coronary artery disease and correlated with decreased ejection fraction. VAP-1 concentration correlated also with left ventricular ejection fraction (r = -0.23, P = .013). Hypertensive patients with diabetes mellitus had almost statistically significant higher VAP-1 concentration compared with hypertensive patients without diabetes mellitus (Me = 403.22 ng/mL vs. Me = 326,68 ng/mL, P = .064). In multiple regression analysis, renalase was predicted by plasma dopamine and norepinephrine as also diastolic office blood pressure and left ventricle ejection fraction. Circulating renalase and VAP-1 levels are elevated in patients with poor blood pressure control. Its correlation with noradrenalin concentration need further studies to find out the role of renalase as also VAP-1 in pathogenesis and treatment of hypertension.

  16. Cellular localization and trafficking of vascular adhesion protein-1 as revealed by an N-terminal GFP fusion protein.

    PubMed

    Weston, Chris J; Shepherd, Emma L; Adams, David H

    2013-06-01

    Recent studies of vascular adhesion protein-1 (VAP-1) have greatly advanced our understanding of the important role this protein plays in the establishment and progression of inflammatory disease. To facilitate more detailed studies on the function of VAP-1, we developed a GFP-fusion protein that enabled us to monitor the trafficking of the protein in three selected cell types: hepatic sinusoidal endothelial cells, liver myofibroblasts and an hepatic stellate cell line (LX-2). The fusion protein was detected as punctate cytoplasmic GFP staining, but was present only at low levels at the cell surface in all cell types studied. The subcellular distribution of the protein was not altered in a catalytically inactive mutant form of the protein (Tyr471Phe) or in the presence of exogenous VAP-1 substrate (methylamine) or inhibitor (semicarbazide). The GFP-VAP-1 protein was localized to the Golgi apparatus (GM-130), endoplasmic reticulum (GRP94) and early endosomes (EEA-1). Additional staining for VAP-1 revealed that the overexpressed protein was also present in vesicles that were negative for GFP fluorescent signal and did not express EEA-1. We propose that these vesicles are responsible for recycling the fusion protein and that the fluorescence of the GFP moiety is quenched at the low pH within these vesicles. This feature of the protein makes it well suited for live cell imaging studies where we wish to track protein that is being actively trafficked within the cell in preference to that which is being recycled.

  17. VCAM-1 and VAP-1 recruit myeloid cells that promote pulmonary metastasis in mice.

    PubMed

    Ferjančič, Špela; Gil-Bernabé, Ana M; Hill, Sally A; Allen, Philip D; Richardson, Peter; Sparey, Tim; Savory, Edward; McGuffog, Jane; Muschel, Ruth J

    2013-04-18

    Pulmonary metastasis is a frequent cause of poor outcome in cancer patients. The formation of pulmonary metastasis is greatly facilitated by recruitment of myeloid cells, which are crucial for tumor cell survival and extravasation. During inflammation, homing of myeloid cells is mediated by endothelial activation, raising the question of a potential role for endothelial activation in myeloid cell recruitment during pulmonary metastasis. Here, we show that metastatic tumor cell attachment causes the induction of the endothelial activation markers vascular cell adhesion molecule-1 (VCAM-1) and vascular adhesion protein-1 (VAP-1). Induction of VCAM-1 is dependent on tumor cell-clot formation, decreasing upon induction of tissue factor pathway inhibitor or treatment with hirudin. Furthermore, inhibition of endothelial activation with a VCAM-1 blocking antibody or a VAP-1 small molecule inhibitor leads to reduced myeloid cell recruitment and diminished tumor cell survival and metastasis without affecting tumor cell adhesion. Simultaneous inhibition of VCAM-1 and VAP-1 does not result in further reduction in myeloid cell recruitment and tumor cell survival, suggesting that both act through closely related mechanisms. These results establish VCAM-1 and VAP-1 as mediators of myeloid cell recruitment in metastasis and identify VAP-1 as a potential target for therapeutic intervention to combat early metastasis.

  18. Lack of association between VAP-1/SSAO activity and corneal neovascularization in a rabbit model.

    PubMed

    Énzsöly, Anna; Markó, Katalin; Tábi, Tamás; Szökő, Éva; Zelkó, Romána; Tóth, Miklós; Petrash, J Mark; Mátyus, Péter; Németh, János

    2013-06-01

    The aim of this study is to determine the efficacy of a potent and specific vascular adhesive protein-1/semicarbazide-sensitive amine oxidase (VAP-1/SSAO) inhibitor, LJP 1207, as a potential antiangiogenic and anti-inflammatory agent in the therapy of corneal neovascularization. Corneal neovascularization was induced with intrastromal suturing in rabbits (n = 20). Topical treatment with VAP-1/SSAO inhibitor LJP 1207 (n = 5, 4 times a day), bevacizumab (n = 5, daily), their combination (n = 5) and vehicle only (n = 5, 4 times a day) were applied postoperatively for 2 weeks. The development and extent of corneal neovascularization were evaluated by digital image analysis. At the end of the observation period, the level of corneal and serum VAP-1/SSAO activity was measured fluorometrically and radiochemically. The corneal VAP-1/SSAO activity was significantly elevated in the suture-challenged vehicle-treated group (3,075 ± 1,009 pmol/mg/h) as compared to unoperated controls (464.2 ± 135 pmol/mg/h, p < 0.001). Treatment with LJP 1207 resulted in slower early phase neovascularization compared to vehicle-treated animals (not significant). At days 7-14, there was no significant difference in the extent of corneal neovascularization between inhibitor- and vehicle-treated corneas, even though inhibitor treatment caused a normalization of corneal VAP-1/SSAO activity (885 ± 452 pmol/mg/h). Our results demonstrate that the significant elevation of VAP-1/SSAO activity due to corneal injury can be prevented with VAP-1/SSAO inhibitor LJP 1207 treatment. However, normalization of VAP-1/SSAO activity in this model does not prevent the development of corneal neovascularization.

  19. Immunohistochemical study of semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 in the hippocampal vasculature: pathological synergy of Alzheimer's disease and diabetes mellitus.

    PubMed

    Valente, Tony; Gella, Alejandro; Solé, Montse; Durany, Núria; Unzeta, Mercedes

    2012-10-01

    Semicarbazide-sensitive amine oxidase/vascular adhesion protein-1 (SSAO/VAP-1) is involved in vascular endothelial damage as well as in the vascular degeneration underlying diabetes mellitus and Alzheimer's disease (AD). Recent evidence suggests that classic pathological features of AD are more pronounced in diabetic mellitus patients. To investigate the expression and distribution of SSAO/VAP-1 in the two pathologies, we have performed an immunohistochemical study in human hippocampal vessels of AD, AD with diabetic mellitus (ADD), diabetic mellitus (DM), and nondemented (ND) patients. The present results demonstrate major vessel accumulation of both SSAO/VAP-1 and amyloid-β immunolabeling intensity in ADD compared with AD patients. Interestingly, nearly damaged vessels with high levels of SSAO/VAP-1 also showed increased oxidative damage markers (AGE, RAGE, and SOD-1) and glial activation (GFAP and HLA). Overall, this work suggests that high vascular SSAO/VAP-1 levels in human hippocampus may contribute to vascular degeneration, which can explain the severe progression in patients with both pathologies.

  20. Glitazones inhibit human monoamine oxidase but their anti-inflammatory actions are not mediated by VAP-1/semicarbazide-sensitive amine oxidase inhibition.

    PubMed

    Carpéné, Christian; Bizou, Mathilde; Tréguer, Karine; Hasnaoui, Mounia; Grès, Sandra

    2015-09-01

    Glitazones are peroxisome proliferator-activated receptor gamma (PPARγ) agonists widely used as antidiabetic drugs also known as thiazolidinediones. Most of them exert other effects such as anti-inflammatory actions via mechanisms supposed to be independent from PPARγ activation (e.g., decreased plasma monocyte chemoattractant protein-1 (MCP-1) levels). Recently, pioglitazone has been shown to inhibit the B form of monoamine oxidase (MAO) in mouse, while rosiglitazone and troglitazone were described as non-covalent inhibitors of both human MAO A and MAO B. Since molecules interacting with MAO might also inhibit semicarbazide-sensitive amine oxidase (SSAO), known as vascular adhesion protein-1 (VAP-1), and since VAP-1/SSAO inhibitors exhibit anti-inflammatory activity, our aim was to elucidate whether VAP-1/SSAO inhibition could be a mechanism involved in the anti-inflammatory behaviour of glitazones. To this aim, MAO and SSAO activities were measured in human subcutaneous adipose tissue biopsies obtained from overweight women undergoing plastic surgery. The production of hydrogen peroxide, an end-product of amine oxidase activity, was determined in tissue homogenates using a fluorometric method. The oxidation of 1 mM tyramine was inhibited by pargyline and almost resistant to semicarbazide, therefore predominantly MAO-dependent. Rosiglitazone was more potent than pioglitazone in inhibiting tyramine oxidation. By contrast, benzylamine oxidation was only abolished by semicarbazide: hence SSAO-mediated. Pioglitazone hampered SSAO activity only when tested at 1 mM while rosiglitazone was inefficient. However, rosiglitazone exhibited anti-inflammatory activity in human adipocytes by limiting MCP-1 expression. Our observations rule out any involvement of VAP-1/SSAO inhibition and subsequent limitation of leukocyte extravasation in the anti-inflammatory action of glitazones.

  1. PXS-4681A, a potent and selective mechanism-based inhibitor of SSAO/VAP-1 with anti-inflammatory effects in vivo.

    PubMed

    Foot, Jonathan S; Yow, Tin T; Schilter, Heidi; Buson, Alberto; Deodhar, Mandar; Findlay, Alison D; Guo, Lily; McDonald, Ian A; Turner, Craig I; Zhou, Wenbin; Jarolimek, Wolfgang

    2013-11-01

    Semicarbazide-sensitive amine oxidase (SSAO), also known as vascular adhesion protein-1 (VAP-1), is a member of the copper-dependent amine oxidase family that is associated with various forms of inflammation and fibrosis. To investigate the therapeutic potential of SSAO/VAP-1 inhibition, potent and selective inhibitors with drug-like properties are required. PXS-4681A [(Z)-4-(2-(aminomethyl)-3-fluoroallyloxy)benzenesulfonamide hydrochloride] is a mechanism-based inhibitor of enzyme function with a pharmacokinetic and pharmacodynamic profile that ensures complete, long-lasting inhibition of the enzyme after a single low dose in vivo. PXS-4681A irreversibly inhibits the enzyme with an apparent Ki of 37 nM and a kinact of 0.26 min(-1) with no observed turnover in vitro. It is highly selective for SSAO/VAP-1 when profiled against related amine oxidases, ion channels, and seven-transmembrane domain receptors, and is superior to previously reported inhibitors. In mouse models of lung inflammation and localized inflammation, dosing of this molecule at 2 mg/kg attenuates neutrophil migration, tumor necrosis factor-α, and interleukin-6 levels. These results demonstrate the drug-like properties of PXS-4681A and its potential use in the treatment of inflammation.

  2. VAP-1 blockade prevents subarachnoid hemorrhage-associated cerebrovascular dilating dysfunction via repression of a neutrophil recruitment-related mechanism.

    PubMed

    Xu, Haoliang; Testai, Fernando D; Valyi-Nagy, Tibor; N Pavuluri, Mani; Zhai, Fengguo; Nanegrungsunk, Danop; Paisansathan, Chanannait; Pelligrino, Dale A

    2015-04-01

    Our previous findings indicated that in rats subjected to subarachnoid hemorrhage (SAH), suppression of post-SAH neuroinflammation via vascular adhesion protein-1 (VAP-1) blockade provides significant neuroprotection. We and others have reported that neuroinflammation contributes to cerebral microvascular impairment. Thus, in the present study, we tested the hypotheses that: (1) treatment with LJP-1586, a selective VAP-1 blocker, prevents SAH-associated pial arteriolar dilating dysfunction; and (2) the vasculoprotective effect of LJP-1586 arises from inhibiting SAH-elicited neutrophil recruitment. We utilized an endovascular perforation model of SAH. Rats subjected to SAH were either treated with LJP-1586 or rendered neutropenic via anti-neutrophil-antibody treatment. Findings from these groups were compared to their respective control groups. At 48 h post-SAH, rats were evaluated for neurobehavioral function, pial venular leukocyte trafficking, and pial arteriolar reactivity to topically-applied acetylcholine (ACh) and S-nitroso-N-acetyl penicillamine (SNAP). Pial arteriolar responses decreased at 48 h post-SAH. However, in the presence of LJP-1586, those responses were significantly preserved. Neutrophil-depletion yielded a substantial suppression of SAH-associated leukocyte adhesion and infiltration. This was accompanied by a significant preservation of pial arteriolar dilating function, suggesting a direct link between neutrophil recruitment and the loss of cerebral microvascular reactivity. Moreover, neutrophil depletion also was associated with significant protection of neurobehavioral function. The present findings suggest that attenuating SAH-linked elevation in neutrophil trafficking will protect against the development of microvascular dysfunction and subsequent neurological impairment.

  3. Glutamate Receptor Interacting Protein 1 Mediates Platelet Adhesion and Thrombus Formation.

    PubMed

    Modjeski, Kristina L; Ture, Sara K; Field, David J; Cameron, Scott J; Morrell, Craig N

    2016-01-01

    Thrombosis-associated pathologies, such as myocardial infarction and stroke, are major causes of morbidity and mortality worldwide. Because platelets are necessary for hemostasis and thrombosis, platelet directed therapies must balance inhibiting platelet function with bleeding risk. Glutamate receptor interacting protein 1 (GRIP1) is a large scaffolding protein that localizes and organizes interacting proteins in other cells, such as neurons. We have investigated the role of GRIP1 in platelet function to determine its role as a molecular scaffold in thrombus formation. Platelet-specific GRIP1-/- mice were used to determine the role of GRIP1 in platelets. GRIP1-/- mice had normal platelet counts, but a prolonged bleeding time and delayed thrombus formation in a FeCl3-induced vessel injury model. In vitro stimulation of WT and GRIP1-/- platelets with multiple agonists showed no difference in platelet activation. However, in vivo platelet rolling velocity after endothelial stimulation was significantly greater in GRIP1-/- platelets compared to WT platelets, indicating a potential platelet adhesion defect. Mass spectrometry analysis of GRIP1 platelet immunoprecipitation revealed enrichment of GRIP1 binding to GPIb-IX complex proteins. Western blots confirmed the mass spectrometry findings that GRIP1 interacts with GPIbα, GPIbβ, and 14-3-3. Additionally, in resting GRIP1-/- platelets, GPIbα and 14-3-3 have increased interaction compared to WT platelets. GRIP1 interactions with the GPIb-IX binding complex are necessary for normal platelet adhesion to a stimulated endothelium. PMID:27631377

  4. Calcium- and integrin-binding protein 1 regulates megakaryocyte ploidy, adhesion, and migration

    PubMed Central

    Kostyak, John C.; Naik, Meghna U.

    2012-01-01

    Megakaryocytes are large, polyploid cells that produce platelets. We have previously reported that calcium- and integrin-binding protein 1 (CIB1) regulates endomitosis in Dami cells. To further characterize the role of CIB1 in megakaryopoiesis, we used a Cib1−/− mouse model. Cib1−/− mice have more platelets and BM megakaryocytes than wild-type (WT) controls (P < .05). Furthermore, subsequent analysis of megakaryocyte-CFU production revealed an increase with Cib1 deletion compared with WT (P < .05). In addition, BM from Cib1−/− mice, cultured with thrombopoietin (TPO) for 24 hours, produced more highly polyploid megakaryocytes than WT BM (P < .05). Subsequent analysis of TPO signaling revealed enhanced Akt and ERK1/2 phosphorylation, whereas FAKY925 phosphorylation was reduced in Cib1−/− megakaryocytes treated with TPO. Conversely, platelet recovery in Cib1−/− mice after platelet depletion was attenuated compared with WT (P < .05). This could be the result of impaired adhesion and migration, as adhesion to fibrinogen and fibronectin and migration toward an SDF-1α gradient were reduced in Cib1−/− megakaryocytes compared with WT (P < .05). In addition, Cib1−/− megakaryocytes formed fewer proplatelets compared with WT (P < .05), when plated on fibrinogen. These data suggest that CIB1 plays a dual role in megakaryopoiesis, initially by negatively regulating TPO signaling and later by augmenting proplatelet production. PMID:22128142

  5. Glutamate Receptor Interacting Protein 1 Mediates Platelet Adhesion and Thrombus Formation

    PubMed Central

    Modjeski, Kristina L.; Ture, Sara K.; Field, David J.; Cameron, Scott J.; Morrell, Craig N.

    2016-01-01

    Thrombosis-associated pathologies, such as myocardial infarction and stroke, are major causes of morbidity and mortality worldwide. Because platelets are necessary for hemostasis and thrombosis, platelet directed therapies must balance inhibiting platelet function with bleeding risk. Glutamate receptor interacting protein 1 (GRIP1) is a large scaffolding protein that localizes and organizes interacting proteins in other cells, such as neurons. We have investigated the role of GRIP1 in platelet function to determine its role as a molecular scaffold in thrombus formation. Platelet-specific GRIP1-/- mice were used to determine the role of GRIP1 in platelets. GRIP1-/- mice had normal platelet counts, but a prolonged bleeding time and delayed thrombus formation in a FeCl3-induced vessel injury model. In vitro stimulation of WT and GRIP1-/- platelets with multiple agonists showed no difference in platelet activation. However, in vivo platelet rolling velocity after endothelial stimulation was significantly greater in GRIP1-/- platelets compared to WT platelets, indicating a potential platelet adhesion defect. Mass spectrometry analysis of GRIP1 platelet immunoprecipitation revealed enrichment of GRIP1 binding to GPIb-IX complex proteins. Western blots confirmed the mass spectrometry findings that GRIP1 interacts with GPIbα, GPIbβ, and 14-3-3. Additionally, in resting GRIP1-/- platelets, GPIbα and 14-3-3 have increased interaction compared to WT platelets. GRIP1 interactions with the GPIb-IX binding complex are necessary for normal platelet adhesion to a stimulated endothelium. PMID:27631377

  6. Induction of the neural cell adhesion molecule and neuronal aggregation by osteogenic protein 1.

    PubMed Central

    Perides, G; Safran, R M; Rueger, D C; Charness, M E

    1992-01-01

    The neural cell adhesion molecule (N-CAM) plays a fundamental role in nervous system development and regeneration, yet the regulation of the expression of N-CAM in different brain regions has remained poorly understood. Osteogenic protein 1 (OP-1) is a member of the transforming growth factor beta superfamily that is expressed in the nervous system. Treatment of the neuroblastoma-glioma hybrid cell line NG108-15 for 1-4 days with recombinant human OP-1 (hOP-1) induced alterations in cell shape, formation of epithelioid sheets, and aggregation of cells into multilayered clusters. Immunofluorescence studies and Western blots demonstrated a striking differential induction of the three N-CAM isoforms in hOP-1-treated cells. hOP-1 caused a 6-fold up-regulation of the 140-kDa N-CAM, the isoform showing the highest constitutive expression, and a 29-fold up-regulation of the 180-kDa isoform. The 120-kDa isoform was not detected in control NG108-15 cells but was readily identified in hOP-1-treated cells. Incubation of NG108-15 cells with an antisense N-CAM oligonucleotide reduced the induction of N-CAM by hOP-1 and decreased the formation of multilayered cell aggregates. Anti-N-CAM monoclonal antibodies also diminished the formation of multilayered cell aggregates by hOP-1 and decreased cell-cell adhesion when hOP-1-treated NG108-15 cells were dispersed and replated. Thus, hOP-1 produces morphologic changes in NG108-15 cells, at least in part, by inducing N-CAM. These observations suggest that OP-1 or a homologue may participate in the regulation of N-CAM during nervous system development and regeneration. Images PMID:1438217

  7. Low density lipoprotein receptor-related protein 1 mediated endocytosis of β1-integrin influences cell adhesion and cell migration.

    PubMed

    Rabiej, Verena K; Pflanzner, Thorsten; Wagner, Timo; Goetze, Kristina; Storck, Steffen E; Eble, Johannes A; Weggen, Sascha; Mueller-Klieser, Wolfgang; Pietrzik, Claus U

    2016-01-01

    The low density lipoprotein receptor-related protein 1 (LRP1) has been shown to interact with β1-integrin and regulate its surface expression. LRP1 knock-out cells exhibit altered cytoskeleton organization and decreased cell migration. Here we demonstrate coupled endocytosis of LRP1 and β1-integrin and the involvement of the intracellular NPxY2 motif of LRP1 in this process. Mouse embryonic fibroblasts harboring a knock in replacement of the NPxY2 motif of LRP1 by a multiple alanine cassette (AAxA) showed elevated surface expression of β1-integrin and decreased β1-integrin internalization rates. As a consequence, cell spreading was altered and adhesion rates were increased in our cell model. Cells formed more focal adhesion complexes, whereby in vitro cell migration rates were decreased. Similar results could be observed in a corresponding mouse model, the C57Bl6 LRP1 NPxYxxL knock in mice, therefore, the biochemistry of cellular adhesion was altered in primary cortical neurons. In vivo cell migration experiments demonstrated a disturbance of neuroblast cell migration along the rostral migratory stream. In summary, our results indicate that LRP1 interacts with β1-integrin mediating integrin internalization and thus correlates with downstream signaling of β1-integrin such as focal adhesion dynamics. Consequently, the disturbance of this interaction resulted in a dysfunction in in vivo and in vitro cell adhesion and cell migration.

  8. A standardized bamboo leaf extract inhibits monocyte adhesion to endothelial cells by modulating vascular cell adhesion protein-1

    PubMed Central

    Choi, Sunga; Park, Myoung Soo; Lee, Yu Ran; Lee, Young Chul; Kim, Tae Woo; Do, Seon-Gil; Kim, Dong Seon

    2013-01-01

    Bamboo leaves (Phyllostachys pubescens Mazel ex J. Houz (Poacea)) have a long history of food and medical applications in Asia, including Japan and Korea. They have been used as a traditional medicine for centuries. We investigated the mechanism of anti-inflammatory activity of a bamboo leaf extract (BLE) on tumor necrosis factor-alpha (TNF-α)-induced monocyte adhesion in human umbilical vein endothelial cells (HUVECs). Exposure of HUVECs to BLE did not inhibit cell viability or cause morphological changes at concentrations ranging from 1 µg/ml to 1 mg/ml. Treatment with 0.1 mg/ml BLE caused 63% inhibition of monocyte adhesion in TNF-α-activated HUVECs, which was associated with 38.4% suppression of vascular cell adhesion molecule-1 expression. Furthermore, TNF-α-induced reactive oxygen species generation was decreased to 47.9% in BLE treated TNF-α-activated HUVECs. BLE (0.05 mg/ml) also caused about 50% inhibition of interleukin-6 secretion from lipopolysaccharide-stimulated monocyte. The results indicate that BLE may be clinically useful as an anti-inflammatory or anti-oxidant for human cardiovascular disease including atherosclerosis. PMID:23422838

  9. Facilitation of cell adhesion by immobilized dengue viral nonstructural protein 1 (NS1): arginine-glycine-aspartic acid structural mimicry within the dengue viral NS1 antigen.

    PubMed

    Chang, Hsin-Hou; Shyu, Huey-Fen; Wang, Yo-Ming; Sun, Der-Shan; Shyu, Rong-Hwa; Tang, Shiao-Shek; Huang, Yao-Shine

    2002-09-15

    Dengue virus infection causes life-threatening hemorrhagic fever. Increasing evidence implies that dengue viral nonstructural protein 1 (NS1) exhibits a tendency to elicit potentially hazardous autoantibodies, which show a wide spectrum of specificity against extracellular matrix and platelet antigens. How NS1 elicits autoantibodies remains unclear. To address the hypothesis that NS1 and matrix proteins may have structural and functional similarity, cell-matrix and cell-NS1 interactions were evaluated using a cell-adhesion assay. The present study showed that dengue NS1 immobilized on coverslips resulted in more cell adhesion than did the control proteins. This cell adhesion was inhibited by peptides containing arginine-glycine-aspartic acid (RGD), a motif important for integrin-mediated cell adhesion. In addition, anti-NS1 antibodies blocked RGD-mediated cell adhesion. Although there is no RGD motif in the NS1 protein sequence, these data indicate that RGD structural mimicry exists within the NS1 antigen.

  10. Secreted Frizzled-related protein 1 (sFRP1) regulates spermatid adhesion in the testis via dephosphorylation of focal adhesion kinase and the nectin-3 adhesion protein complex

    PubMed Central

    Wong, Elissa W. P.; Lee, Will M.; Cheng, C. Yan

    2013-01-01

    Development of spermatozoa in adult mammalian testis during spermatogenesis involves extensive cell migration and differentiation. Spermatogonia that reside at the basal compartment of the seminiferous epithelium differentiate into more advanced germ cell types that migrate toward the apical compartment until elongated spermatids are released into the tubule lumen during spermiation. Apical ectoplasmic specialization (ES; a testis-specific anchoring junction) is the only cell junction that anchors and maintains the polarity of elongating/elongated spermatids (step 8–19 spermatids) in the epithelium. Little is known regarding the signaling pathways that trigger the disassembly of the apical ES at spermiation. Here, we show that secreted Frizzled-related protein 1 (sFRP1), a putative tumor suppressor gene that is frequently down-regulated in multiple carcinomas, is a crucial regulatory protein for spermiation. The expression of sFRP1 is tightly regulated in adult rat testis to control spermatid adhesion and sperm release at spermiation. Down-regulation of sFRP1 during testicular development was found to coincide with the onset of the first wave of spermiation at approximately age 45 d postpartum, implying that sFRP1 might be correlated with elongated spermatid adhesion conferred by the apical ES before spermiation. Indeed, administration of sFRP1 recombinant protein to the testis in vivo delayed spermiation, which was accompanied by down-regulation of phosphorylated (p)-focal adhesion kinase (FAK)-Tyr397 and retention of nectin-3 adhesion protein at the apical ES. To further investigate the functional relationship between p-FAK-Tyr397 and localization of nectin-3, we overexpressed sFRP1 using lentiviral vectors in the Sertoli-germ cell coculture system. Consistent with the in vivo findings, overexpression of sFRP1 induced down-regulation of p-FAK-Tyr397, leading to a decline in phosphorylation of nectin-3. In summary, this report highlights the critical role of s

  11. Amyloid precursor-like protein 1 (APLP1) exhibits stronger zinc-dependent neuronal adhesion than amyloid precursor protein and APLP2.

    PubMed

    Mayer, Magnus C; Schauenburg, Linda; Thompson-Steckel, Greta; Dunsing, Valentin; Kaden, Daniela; Voigt, Philipp; Schaefer, Michael; Chiantia, Salvatore; Kennedy, Timothy E; Multhaup, Gerhard

    2016-04-01

    The amyloid precursor protein (APP) and its paralogs, amyloid precursor-like protein 1 (APLP1) and APLP2, are metalloproteins with a putative role both in synaptogenesis and in maintaining synapse structure. Here, we studied the effect of zinc on membrane localization, adhesion, and secretase cleavage of APP, APLP1, and APLP2 in cell culture and rat neurons. For this, we employed live-cell microscopy techniques, a microcontact printing adhesion assay and ELISA for protein detection in cell culture supernatants. We report that zinc induces the multimerization of proteins of the amyloid precursor protein family and enriches them at cellular adhesion sites. Thus, zinc facilitates the formation of de novo APP and APLP1 containing adhesion complexes, whereas it does not have such influence on APLP2. Furthermore, zinc-binding prevented cleavage of APP and APLPs by extracellular secretases. In conclusion, the complexation of zinc modulates neuronal functions of APP and APLPs by (i) regulating formation of adhesion complexes, most prominently for APLP1, and (ii) by reducing the concentrations of neurotrophic soluble APP/APLP ectodomains. Earlier studies suggest a function of the amyloid precursor protein (APP) family proteins in neuronal adhesion. We report here that adhesive function of these proteins is tightly regulated by zinc, most prominently for amyloid precursor-like protein 1 (APLP1). Zinc-mediated APLP1 multimerization, which induced formation of new neuronal contacts and decreased APLP1 shedding. This suggests that APLP1 could function as a zinc receptor processing zinc signals to stabilized or new neuronal contacts.

  12. Amyloid precursor-like protein 1 (APLP1) exhibits stronger zinc-dependent neuronal adhesion than amyloid precursor protein and APLP2.

    PubMed

    Mayer, Magnus C; Schauenburg, Linda; Thompson-Steckel, Greta; Dunsing, Valentin; Kaden, Daniela; Voigt, Philipp; Schaefer, Michael; Chiantia, Salvatore; Kennedy, Timothy E; Multhaup, Gerhard

    2016-04-01

    The amyloid precursor protein (APP) and its paralogs, amyloid precursor-like protein 1 (APLP1) and APLP2, are metalloproteins with a putative role both in synaptogenesis and in maintaining synapse structure. Here, we studied the effect of zinc on membrane localization, adhesion, and secretase cleavage of APP, APLP1, and APLP2 in cell culture and rat neurons. For this, we employed live-cell microscopy techniques, a microcontact printing adhesion assay and ELISA for protein detection in cell culture supernatants. We report that zinc induces the multimerization of proteins of the amyloid precursor protein family and enriches them at cellular adhesion sites. Thus, zinc facilitates the formation of de novo APP and APLP1 containing adhesion complexes, whereas it does not have such influence on APLP2. Furthermore, zinc-binding prevented cleavage of APP and APLPs by extracellular secretases. In conclusion, the complexation of zinc modulates neuronal functions of APP and APLPs by (i) regulating formation of adhesion complexes, most prominently for APLP1, and (ii) by reducing the concentrations of neurotrophic soluble APP/APLP ectodomains. Earlier studies suggest a function of the amyloid precursor protein (APP) family proteins in neuronal adhesion. We report here that adhesive function of these proteins is tightly regulated by zinc, most prominently for amyloid precursor-like protein 1 (APLP1). Zinc-mediated APLP1 multimerization, which induced formation of new neuronal contacts and decreased APLP1 shedding. This suggests that APLP1 could function as a zinc receptor processing zinc signals to stabilized or new neuronal contacts. PMID:26801522

  13. The ancillary protein 1 of Streptococcus pyogenes FCT-1 pili mediates cell adhesion and biofilm formation through heterophilic as well as homophilic interactions

    PubMed Central

    Becherelli, Marco; Manetti, Andrea G O; Buccato, Scilla; Viciani, Elisa; Ciucchi, Laura; Mollica, Giulia; Grandi, Guido; Margarit, Imma

    2012-01-01

    Summary Gram-positive pili are known to play a role in bacterial adhesion to epithelial cells and in the formation of biofilm microbial communities. In the present study we undertook the functional characterization of the pilus ancillary protein 1 (AP1_M6) from Streptococcus pyogenes isolates expressing the FCT-1 pilus variant, known to be strong biofilm formers. Cell binding and biofilm formation assays using S. pyogenes in-frame deletion mutants, Lactococcus expressing heterologous FCT-1 pili and purified recombinant AP1_M6, indicated that this pilin is a strong cell adhesin that is also involved in bacterial biofilm formation. Moreover, we show that AP1_M6 establishes homophilic interactions that mediate inter-bacterial contact, possibly promoting bacterial colonization of target epithelial cells in the form of three-dimensional microcolonies. Finally, AP1_M6 knockout mutants were less virulent in mice, indicating that this protein is also implicated in GAS systemic infection. PMID:22320452

  14. Cilostazol prevents remnant lipoprotein particle-induced monocyte adhesion to endothelial cells by suppression of adhesion molecules and monocyte chemoattractant protein-1 expression via lectin-like receptor for oxidized low-density lipoprotein receptor activation.

    PubMed

    Park, So Youn; Lee, Jeong Hyun; Kim, Yong Ki; Kim, Chi Dae; Rhim, Byung Yong; Lee, Won Suk; Hong, Ki Whan

    2005-03-01

    This study shows cilostazol effect to prevent remnant lipoprotein particle (RLP)-induced monocyte adhesion to human umbilical vein endothelial cells (HUVECs). Upon incubation of HUVECs with RLP (50 microg/ml), adherent monocytes significantly increased by 3.3-fold with increased cell surface expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1, E-selectin, and monocyte chemoattractant protein-1 (MCP-1). Cilostazol ( approximately 1-100 microM) concentration dependently repressed these variables as did (E)3-[(4-t-butylphenyl)sulfonyl]-2-propenenitrile (BAY 11-7085) (10 microM), a specific nuclear factor-kappaB (NF-kappaB) inhibitor. Cilostazol effects were significantly antagonized by iberiotoxin (1 microM), a maxi-K channel blocker. RLP significantly increased expression of lectin-like receptor for oxidized low-density lipoprotein (LDL) (LOX-1) receptor protein. Upon transfection with antisense LOX-1 oligodeoxynucleotide (As-LOX-1), LOX-1 receptor expression was reduced, whereas HUVECs with sense LOX-1 oligodeoxynucleotide did express high LOX-1 receptor. RLP-stimulated superoxide and tumor necrosis factor-alpha levels were significantly lowered with decreased expression of VCAM-1 and MCP-1 by transfection with As-LOX-1 as did polyinosinic acid (10 microg/ml, a LOX-1 receptor inhibitor). RLP significantly degraded inhibitory kappaBalpha in the cytoplasm and activated nuclear factor-kappaB (NF-kappaB) p65 in the nucleus of HUVECs with increased luciferase activity of NF-kappaB, all of which were reversed by cilostazol (10 microM), BAY 11-7085, and polyinosinic acid. Together, cilostazol suppresses RLP-stimulated increased monocyte adhesion to HUVECs by suppression of LOX-1 receptor-coupled NF-kappaB-dependent nuclear transcription via mediation of the maxi-K channel opening.

  15. α2-Macroglobulin Can Crosslink Multiple Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) Molecules and May Facilitate Adhesion of Parasitized Erythrocytes.

    PubMed

    Stevenson, Liz; Laursen, Erik; Cowan, Graeme J; Bandoh, Betty; Barfod, Lea; Cavanagh, David R; Andersen, Gregers R; Hviid, Lars

    2015-07-01

    Rosetting, the adhesion of Plasmodium falciparum-infected erythrocytes to uninfected erythrocytes, involves clonal variants of the parasite protein P. falciparum erythrocyte membrane protein 1 (PfEMP1) and soluble serum factors. While rosetting is a well-known phenotypic marker of parasites associated with severe malaria, the reason for this association remains unclear, as do the molecular details of the interaction between the infected erythrocyte (IE) and the adhering erythrocytes. Here, we identify for the first time a single serum factor, the abundant serum protease inhibitor α2-macroglobulin (α2M), which is both required and sufficient for rosetting mediated by the PfEMP1 protein HB3VAR06 and some other rosette-mediating PfEMP1 proteins. We map the α2M binding site to the C terminal end of HB3VAR06, and demonstrate that α2M can bind at least four HB3VAR06 proteins, plausibly augmenting their combined avidity for host receptors. IgM has previously been identified as a rosette-facilitating soluble factor that acts in a similar way, but it cannot induce rosetting on its own. This is in contrast to α2M and probably due to the more limited cross-linking potential of IgM. Nevertheless, we show that IgM works synergistically with α2M and markedly lowers the concentration of α2M required for rosetting. Finally, HB3VAR06+ IEs share the capacity to bind α2M with subsets of genotypically distinct P. falciparum isolates forming rosettes in vitro and of patient parasite isolates ex vivo. Together, our results are evidence that P. falciparum parasites exploit α2M (and IgM) to expand the repertoire of host receptors available for PfEMP1-mediated IE adhesion, such as the erythrocyte carbohydrate moieties that lead to formation of rosettes. It is likely that this mechanism also affects IE adhesion to receptors on vascular endothelium. The study opens opportunities for broad-ranging immunological interventions targeting the α2M--(and IgM-) binding domains of PfEMP1

  16. Adhesion

    MedlinePlus

    ... as the shoulder Eyes Inside the abdomen or pelvis Adhesions can become larger or tighter over time. ... Other causes of adhesions in the abdomen or pelvis include: Appendicitis , most often when the appendix breaks ...

  17. Plasmodium falciparum erythrocyte membrane protein 1 is a parasitized erythrocyte receptor for adherence to CD36, thrombospondin, and intercellular adhesion molecule 1.

    PubMed Central

    Baruch, D I; Gormely, J A; Ma, C; Howard, R J; Pasloske, B L

    1996-01-01

    Adherence of mature Plasmodium falciparum parasitized erythrocytes (PRBCs) to microvascular endothelium contributes directly to acute malaria pathology. We affinity purified molecules from detergent extracts of surface-radioiodinated PRBCs using several endothelial cell receptors known to support PRBC adherence, including CD36, thrombospondin (TSP), and intercellular adhesion molecule 1 (ICAM-1). All three host receptors affinity purified P. falciparum erythrocyte membrane protein 1 (PfEMP1), a very large malarial protein expressed on the surface of adherent PRBCs. Binding of PfEMP1 to particular host cell receptors correlated with the binding phenotype of the PRBCs from which PfEMP1 was extracted. Preadsorption of PRBC extracts with anti-PfEMP1 antibodies, CD36, or TSP markedly reduced PfEMP1 binding to CD36 or TSP. Mild trypsinization of intact PRBCs of P. falciparum strains shown to express antigenically different PfEMP1 released different (125)I-labeled tryptic fragments of PfEMP1 that bound specifically to CD36 and TSP. In clone C5 and strain MC, these activities resided on different tryptic fragments, but a single tryptic fragment from clone ItG-ICAM bound to both CD36 and TSP. Hence, the CD36- and TSP-binding domains are distinct entities located on a single PfEMP1 molecule. PfEMP1, the malarial variant antigen on infected erythrocytes, is therefore a receptor for CD36, TSP, and ICAM-1. A therapeutic approach to block or reverse adherence of PRBCs to host cell receptors can now be pursued with the identification of PfEMP1 as a malarial receptor for PRBC adherence to host proteins. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8622965

  18. Adhesions

    MedlinePlus

    ... surfaces so they can shift easily as the body moves. Adhesions cause tissues and organs to stick together. They might connect the loops of the intestines to each other, to nearby ... can occur anywhere in the body. But they often form after surgery on the ...

  19. Expression of Adhesion Molecules in Synovia of Patients with Treatment-Resistant Lyme Arthritis

    PubMed Central

    Akin, Evren; Aversa, John; Steere, Allen C.

    2001-01-01

    The expression of adhesion molecules in synovium in patients with Lyme arthritis is surely critical in the control of Borrelia burgdorferi infection but may also have pathologic consequences. For example, molecular mimicry between a dominant T-cell epitope of B. burgdorferi outer surface protein A and an adhesion molecule, human lymphocyte function-associated antigen 1 (LFA-1), has been implicated in the pathogenesis of treatment-resistant Lyme arthritis. Using immunohistochemical methods, we examined synovial samples for expression of adhesion molecules in 29 patients with treatment-resistant Lyme arthritis and in 15 patients with rheumatoid arthritis or chronic inflammatory monoarthritis. In Lyme arthritis synovia, endothelial cells showed intense expression of P-selectin and vascular adhesion protein-1 (VAP-1). Expression of LFA-1 was also intense on infiltrating cells, particularly in lymphoid aggregates, and intercellular adhesion molecule-1 (ICAM-1) was markedly expressed on synovial lining and endothelial and infiltrating cells. Moderate expression of vascular cell adhesion molecule-1 (VCAM-1) was seen on synovial lining and endothelial cells, and mild expression of its ligand, very late antigen-4, was apparent in perivascular lymphoid infiltrates. Except for lesser expression of VCAM-1 in Lyme synovia, the levels of expression of these adhesion molecules were similar in the three patient groups. We conclude that certain adhesion molecules, including ICAM-1 and LFA-1, are expressed intensely in the synovia of patients with Lyme arthritis. Upregulation of LFA-1 on lymphocytes in this lesion may be critical in the pathogenesis of treatment-resistant Lyme arthritis. PMID:11179355

  20. Dentin bond strength of an experimental adhesive system containing calcium chloride, synthetic peptides derived from dentin matrix protein 1 (pA and pB), and hydroxyapatite for direct pulp capping and as a bonding agent.

    PubMed

    Shinkai, Koichi; Taira, Yoshihisa; Suzuki, Masaya; Kato, Chikage; Yamauchi, Junichi; Suzuki, Shiro; Katoh, Yoshiroh

    2010-07-01

    The purpose of this study was to evaluate the microtensile bond strength (microTBS) of an experimental adhesive system containing calcium chloride (CaCl(2)), synthetic peptides derived from dentin matrix protein 1 (DMP1: pA and pB), and hydroxyapatite experimentally developed for direct pulp capping to human dentin. Clearfil SE Bond/Primer (SEP) and Bond (SEB) were used for each experimental group as the matrix agents. Experimental self-etching primers included: primer-I, SEP containing 10 wt% CaCl(2), and primer-II, SEP containing a 10 wt% compound of pA and pB. The experimental bonding agent was a mixture of SEB and 10 wt% hydroxyapatite. Specimens were divided into five experimental groups, including the control, according to the mode of primer application. Primer-I was primarily applied, followed by primer-II for group 1, primer-I as the primary and SEP as the secondary for group 2, SEP as the primary and primer-II as the secondary for group 3, and SEP was applied twice for group 4, and SEP was applied once for the control. Clearfil SE Bond adhesive system was used as the control. Flat dentin surfaces of human molars were assigned to bonding tests. After each experimental primer was applied to the dentin surface, each experimental bonding agent was applied and photopolymerized, and then resin composite paste (Clearfil Flow FX and Clearfil AP-X) was placed and photopolymerized. The specimens were subjected to microTBS testing. The data were compared using analysis of variance (ANOVA) and post-hoc Bonferroni/Dunn tests. Results showed that the minimum mean value of microTBS was 15.4 MPa for group 1, while the maximum mean value of microTBS was 52.7 MPa for the control. There were significant differences among the experimental groups, except for group 4 and the control. The experimental primers containing CaCl(2) or DMP1 negatively affected the microTBS value of the experimental adhesive system to dentin.

  1. Rosetting Plasmodium falciparum-infected erythrocytes bind to human brain microvascular endothelial cells in vitro, demonstrating a dual adhesion phenotype mediated by distinct P. falciparum erythrocyte membrane protein 1 domains.

    PubMed

    Adams, Yvonne; Kuhnrae, Pongsak; Higgins, Matthew K; Ghumra, Ashfaq; Rowe, J Alexandra

    2014-03-01

    Adhesion interactions between Plasmodium falciparum-infected erythrocytes (IE) and human cells underlie the pathology of severe malaria. IE cytoadhere to microvascular endothelium or form rosettes with uninfected erythrocytes to survive in vivo by sequestering IE in the microvasculature and avoiding splenic clearance mechanisms. Both rosetting and cytoadherence are mediated by the parasite-derived IE surface protein family Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). Rosetting and cytoadherence have been widely studied as separate entities; however, the ability of rosetting P. falciparum strains to cytoadhere has received little attention. Here, we show that IE of the IT/R29 strain expressing a rosette-mediating PfEMP1 variant (IT4var09) cytoadhere in vitro to a human brain microvascular endothelial cell line (HBEC-5i). Cytoadherence was inhibited by heparin and by treatment of HBEC-5i with heparinase III, suggesting that the endothelial receptors for IE binding are heparan sulfate proteoglycans. Antibodies to the N-terminal regions of the IT4var09 PfEMP1 variant (NTS-DBL1α and DBL2γ domains) specifically inhibited and reversed cytoadherence down to low concentrations (<10 μg/ml of total IgG). Surface plasmon resonance experiments showed that the NTS-DBLα and DBL2γ domains bind strongly to heparin, with half-maximal binding at a concentration of ∼0.5 μM in both cases. Therefore, cytoadherence of IT/R29 IE is distinct from rosetting, which is primarily mediated by NTS-DBL1α interactions with complement receptor 1. These data show that IT4var09-expressing parasites are capable of dual interactions with both endothelial cells and uninfected erythrocytes via distinct receptor-ligand interactions.

  2. Expression of mRNAs coding for VAP1/crotastatin-like metalloproteases in the venom glands of three South American pit vipers assessed by quantitative real-time PCR.

    PubMed

    Tavares, N A C; Correia, J M; Guarnieri, M C; Lima-Filho, J L; Prieto-da-Silva, A R B; Rádis-Baptista, G

    2008-12-15

    Snake venom metalloproteases encompass a large family of toxins, with approximately 200 members already catalogued, which exhibit a diversity of structures and biological functions. From this relatively large number, only a dozen examples of apoptosis-inducing metalloproteases, like VAP1 and 2 from the venom of Crotalus atrox, are known. Since most VAP1-like toxins ever characterized were purified from the venom of Viperidae species inhabiting diverse places on earth, we investigate the expression of VAP-like metalloproteases in the venom gland of three representative pit vipers of the Brazilian territory. By molecular cloning and quantitative real-time polymerase chain reaction, using as calibrator gene the Crotalus durissus terrificus homolog of VAP1, named crotastatin, it is reported here that VAP1/crotastatin-like homologues in the venom gland of Bothrops atrox, C. d. cascavella and Lachesis m. rhombeata are expressed at different levels. Hence, batroxstatins, the crotastatin-like precursors from B. atrox, are expressed 87 times more than crotastatin-1, from C. d. cascavella, and 7.5-fold that lachestatins, from L. m. rhombeata. Moreover, in silico structural analysis of amino acid sequences indicates that batroxstatin-2, crotastatins and lachestatin-1 and -2 which share the archetypal motifs and metal- binding sites of VAP1, are subgrouped in a branch that comprises some apoptosis-inducing toxins. PMID:18926840

  3. Adhesive plasters

    DOEpatents

    Holcombe, Jr., Cressie E.; Swain, Ronald L.; Banker, John G.; Edwards, Charlene C.

    1978-01-01

    Adhesive plaster compositions are provided by treating particles of Y.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Gd.sub.2 O.sub.3 or Nd.sub.2 O.sub.3 with dilute acid solutions. The resulting compositions have been found to spontaneously harden into rigid reticulated masses resembling plaster of Paris. Upon heating, the hardened material is decomposed into the oxide, yet retains the reticulated rigid structure.

  4. AUXIN BINDING PROTEIN1: The Outsider

    PubMed Central

    Sauer, Michael; Kleine-Vehn, Jürgen

    2011-01-01

    AUXIN BINDING PROTEIN1 (ABP1) is one of the first characterized proteins that bind auxin and has been implied as a receptor for a number of auxin responses. Early studies characterized its auxin binding properties and focused on rapid electrophysiological and cell expansion responses, while subsequent work indicated a role in cell cycle and cell division control. Very recently, ABP1 has been ascribed a role in modulating endocytic events at the plasma membrane and RHO OF PLANTS-mediated cytoskeletal rearrangements during asymmetric cell expansion. The exact molecular function of ABP1 is still unresolved, but its main activity apparently lies in influencing events at the plasma membrane. This review aims to connect the novel findings with the more classical literature on ABP1 and to point out the many open questions that still separate us from a comprehensive model of ABP1 action, almost 40 years after the first reports of its existence. PMID:21719690

  5. Thermal Characterization of Adhesive

    NASA Technical Reports Server (NTRS)

    Spomer, Ken A.

    1999-01-01

    The current Space Shuttle Reusable Solid Rocket Motor (RSRM) nozzle adhesive bond system is being replaced due to obsolescence. Down-selection and performance testing of the structural adhesives resulted in the selection of two candidate replacement adhesives, Resin Technology Group's Tiga 321 and 3M's EC2615XLW. This paper describes rocket motor testing of these two adhesives. Four forty-pound charge motors were fabricated in configurations that would allow side by side comparison testing of the candidate replacement adhesives and the current RSRM adhesives. The motors provided an environment where the thermal performance of adhesives in flame surface bondlines was compared. Results of the FPC testing show that: 1) The phenolic char depths on radial bond lines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used; 2) The adhesive char depth of the candidate replacement adhesives is less than the char depth of the current adhesives; 3) The heat-affected depth of the candidate replacement adhesives is less than the heat-affected depth of the current adhesives; and 4) The ablation rates for both replacement adhesives are slower than that of the current adhesives.

  6. Understanding Marine Mussel Adhesion

    PubMed Central

    Roberto, Francisco F.

    2007-01-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are water-impervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion. PMID:17990038

  7. Understanding Marine Mussel Adhesion

    SciTech Connect

    H. G. Silverman; F. F. Roberto

    2007-12-01

    In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are waterimpervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion.

  8. PH dependent adhesive peptides

    DOEpatents

    Tomich, John; Iwamoto, Takeo; Shen, Xinchun; Sun, Xiuzhi Susan

    2010-06-29

    A novel peptide adhesive motif is described that requires no receptor or cross-links to achieve maximal adhesive strength. Several peptides with different degrees of adhesive strength have been designed and synthesized using solid phase chemistries. All peptides contain a common hydrophobic core sequence flanked by positively or negatively charged amino acids sequences.

  9. Mini-review: barnacle adhesives and adhesion.

    PubMed

    Kamino, Kei

    2013-01-01

    Barnacles are intriguing, not only with respect to their importance as fouling organisms, but also in terms of the mechanism of underwater adhesion, which provides a platform for biomimetic and bioinspired research. These aspects have prompted questions regarding how adult barnacles attach to surfaces under water. The multidisciplinary and interdisciplinary nature of the studies makes an overview covering all aspects challenging. This mini-review, therefore, attempts to bring together aspects of the adhesion of adult barnacles by looking at the achievements of research focused on both fouling and adhesion. Biological and biochemical studies, which have been motivated mainly by understanding the nature of the adhesion, indicate that the molecular characteristics of barnacle adhesive are unique. However, it is apparent from recent advances in molecular techniques that much remains undiscovered regarding the complex event of underwater attachment. Barnacles attached to silicone-based elastomeric coatings have been studied widely, particularly with respect to fouling-release technology. The fact that barnacles fail to attach tenaciously to silicone coatings, combined with the fact that the mode of attachment to these substrata is different to that for most other materials, indicates that knowledge about the natural mechanism of barnacle attachment is still incomplete. Further research on barnacles will enable a more comprehensive understanding of both the process of attachment and the adhesives used. Results from such studies will have a strong impact on technology aimed at fouling prevention as well as adhesion science and engineering.

  10. Adhesion at metal interfaces

    NASA Technical Reports Server (NTRS)

    Banerjea, Amitava; Ferrante, John; Smith, John R.

    1991-01-01

    A basic adhesion process is defined, the theory of the properties influencing metallic adhesion is outlined, and theoretical approaches to the interface problem are presented, with emphasis on first-principle calculations as well as jellium-model calculations. The computation of the energies of adhesion as a function of the interfacial separation is performed; fully three-dimensional calculations are presented, and universality in the shapes of the binding energy curves is considered. An embedded-atom method and equivalent-crystal theory are covered in the framework of issues involved in practical adhesion.

  11. Gecko adhesion: evolutionary nanotechnology.

    PubMed

    Autumn, Kellar; Gravish, Nick

    2008-05-13

    If geckos had not evolved, it is possible that humans would never have invented adhesive nanostructures. Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1ms-1. Climbing presents a significant challenge for an adhesive in requiring both strong attachment and easy rapid removal. Conventional pressure-sensitive adhesives (PSAs) are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). The gecko adhesive differs dramatically from conventional adhesives. Conventional PSAs are soft viscoelastic polymers that degrade, foul, self-adhere and attach accidentally to inappropriate surfaces. In contrast, gecko toes bear angled arrays of branched, hair-like setae formed from stiff, hydrophobic keratin that act as a bed of angled springs with similar effective elastic modulus to that of PSAs. Setae are self-cleaning and maintain function for months during repeated use in dirty conditions. Setae are an anisotropic 'frictional adhesive' in that adhesion requires maintenance of a proximally directed shear load, enabling either a tough bond or spontaneous detachment. Gecko-like synthetic adhesives may become the glue of the future-and perhaps the screw of the future as well.

  12. Electro-dry-adhesion.

    PubMed

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample.

  13. Electro-dry-adhesion.

    PubMed

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample. PMID:22397643

  14. Reversible Thermoset Adhesives

    NASA Technical Reports Server (NTRS)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  15. Neuron adhesion and strengthening

    NASA Astrophysics Data System (ADS)

    Rocha, Aracely; Jian, Kuihuan; Ko, Gladys; Liang, Hong

    2010-07-01

    Understanding the neuron/material adhesion is important for neuron stimulation and growth. The current challenges remain in the lack of precision of measuring techniques and understanding the behavior of neuron. Here, we report a fluid shear method to investigate adhesion at the neuron/poly-D-lysine interface. In this study, the adhesion of 12-day-old chick embryo-retina neurons cultured on poly-D-lysine coated glass coverslips was measured via parallel disk rotational flow. The shear stress experienced by the cells increases with the disk radius. There is a critical point along the radius (Rc) where the stress experienced by the neurons equals their adhesion. The measured Rc can be used to calculate the neuron adhesion. Our results demonstrate that neurons adhered to the poly-D-lysine had a strain hardening effect. The adhesive shear stress of the neuron-material increased with applied shear (τa). When the τa reached or exceeded the value of 40 dyn/cm2, the adhesion remained constant at approximately 30 dyn/cm2. The present work allowed us not only to quantify the adhesive strength and force but also to evaluate the value of strain hardening at the neuron/poly-D-lysine interface.

  16. Postoperative Peritoneal Adhesions

    PubMed Central

    Ryan, Graeme B.; Grobéty, Jocelyne; Majno, Guido

    1971-01-01

    This paper describes an experimental model of peritoneal adhesions, in the rat, based on two relatively minor accidents that may occur during abdominal surgery in man: drying of the serosa, and bleeding. Drying alone had little effect; drying plus bleeding consistently produced adhesions to the dried area. Fresh blood alone produced adhesions between the three membranous structures [omentum and pelvic fat bodies (PFBs)]. The formation of persistent adhesions required whole blood. Preformed clots above a critical size induced adhesions even without previous serosal injury; they were usually captured by the omentum and PFBs. If all three membranous structures were excised, the clots caused visceral adhesions. The protective role of the omentum, its structure, and the mechanism of omental adhesions, are discussed. These findings are relevant to the pathogenesis of post-operative adhesions in man. ImagesFig 3Fig 4Fig 5Fig 6Fig 7Fig 12Fig 13Fig 1Fig 2Fig 14Fig 15Fig 8Fig 9Fig 10Fig 11 PMID:5315369

  17. Instant acting adhesive system

    NASA Technical Reports Server (NTRS)

    Davis, T. R.; Haines, R. C.

    1971-01-01

    Adhesive developes 80 percent of minimum bond strength of 250 psi less than 30 sec after activation is required. Adhesive is stable, handles easily, is a low toxic hazard, and is useful in industrial and domestic prototype bonding and clamping operations.

  18. Adhesives in larynx repair.

    PubMed

    Lyons, M B; Lyons, G D; Webster, D; Wheeler, V R

    1989-04-01

    Guinea pig laryngeal fractures were used as a model to compare the ease of application and effectiveness of the fibrinogen-adhesive system with the ease of application and effectiveness of cyanoacrylate glue and control fractures stinted with contralateral gelatin film. Seven fibrin adhesive-treated and two cyanoacrylate glue-treated guinea pigs were perfused after 60 and 35 days, respectively. The larynges were serial sectioned, and the wound sites were compared. The fibrinogen adhesive system was easier to dispense than cyanoacrylate glue, did not require a completely dry surface, and stabilized within 3 minutes. Cartilage segment alignment with focal, complete fracture healing and symmetrical chondrocyte proliferation were seen in fibrogen adhesive-stinted larynges. In the cyanoacrylate glue-treated larynges, there was no alignment and minimal, asymmetrical chondrocyte proliferation. Gelatin film-stinted controls exhibited similar features. Thus, fibrogen adhesive was easier to apply and more effectively bound laryngeal fractures than cyanoacrylate glue or gelatin film.

  19. Cytotoxicity of denture adhesives.

    PubMed

    de Gomes, Pedro Sousa; Figueiral, Maria Helena; Fernandes, Maria Helena R; Scully, Crispian

    2011-12-01

    Ten commercially available denture adhesives, nine soluble formulations (six creams, three powders) and one insoluble product (pad), were analyzed regarding the cytotoxicity profile in direct and indirect assays using L929 fibroblast cells. In the direct assay, fibroblasts were seeded over the surface of a thick adhesive gel (5%, creams; 2.5%, powders and pad). In the indirect assay, cells were cultured in the presence of adhesive extracts prepared in static and dynamic conditions (0.5-2%, creams; 0.25-1%, powders and pad). Cell toxicity was assessed for cell viability/proliferation (MTT assay) and cell morphology (observation of the F-actin cytoskeleton organization by confocal laser scanning microscopy). Direct contact of the L929 fibroblasts with the thick adhesive gels caused no, or only a slight, decrease in cell viability/proliferation. The adhesive extracts (especially those prepared in dynamic conditions) caused significantly higher growth inhibition of fibroblasts and, in addition, caused dose- and time-dependent effects, throughout the 6-72 h exposure time. Also, dose-dependent effects on cell morphology, with evident disruption of the F-actin cytoskeleton organization, were seen in the presence of most adhesives. In conclusion, the adhesives possessed different degrees of cytotoxicity, but similar dose- and time-dependent biological profiles.

  20. [Endothelial cell adhesion molecules].

    PubMed

    Ivanov, A N; Norkin, I A; Puchin'ian, D M; Shirokov, V Iu; Zhdanova, O Iu

    2014-01-01

    The review presents current data concerning the functional role of endothelial cell adhesion molecules belonging to different structural families: integrins, selectins, cadherins, and the immunoglobulin super-family. In this manuscript the regulatory mechanisms and factors of adhesion molecules expression and distribution on the surface of endothelial cells are discussed. The data presented reveal the importance of adhesion molecules in the regulation of structural and functional state of endothelial cells in normal conditions and in pathology. Particular attention is paid to the importance of these molecules in the processes of physiological and pathological angiogenesis, regulation of permeability of the endothelial barrier and cell transmigration.

  1. Focal adhesions in osteoneogenesis

    PubMed Central

    Biggs, M.J.P; Dalby, M.J

    2010-01-01

    As materials technology and the field of tissue engineering advances, the role of cellular adhesive mechanisms, in particular the interactions with implantable devices, becomes more relevant in both research and clinical practice. A key tenet of medical device technology is to use the exquisite ability of biological systems to respond to the material surface or chemical stimuli in order to help develop next-generation biomaterials. The focus of this review is on recent studies and developments concerning focal adhesion formation in osteoneogenesis, with an emphasis on the influence of synthetic constructs on integrin mediated cellular adhesion and function. PMID:21287830

  2. Cell adhesion force microscopy

    PubMed Central

    Sagvolden, G.; Giaever, I.; Pettersen, E. O.; Feder, J.

    1999-01-01

    The adhesion forces of cervical carcinoma cells in tissue culture were measured by using the manipulation force microscope, a novel atomic force microscope. The forces were studied as a function of time and temperature for cells cultured on hydrophilic and hydrophobic polystyrene substrates with preadsorbed proteins. The cells attached faster and stronger at 37°C than at 23°C and better on hydrophilic than on hydrophobic substrates, even though proteins adsorb much better to the hydrophobic substrates. Because cell adhesion serves to control several stages in the cell cycle, we anticipate that the manipulation force microscope can help clarify some cell-adhesion related issues. PMID:9892657

  3. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  4. A functional analysis of Wnt inducible signalling pathway protein -1 (WISP-1/CCN4).

    PubMed

    Stephens, Sarah; Palmer, Joanne; Konstantinova, Irena; Pearce, Andrew; Jarai, Gabor; Day, Elizabeth

    2015-03-01

    Wnt-1 inducible signalling pathway protein 1 (WISP-1/CCN4) is an extracellular matrix protein that belongs to the Cyr61 (cysteine-rich protein 61), CTGF (connective tissue growth factor) and NOV (CCN) family and plays a role in multiple cellular processes. No specific WISP-1 receptors have been identified but emerging evidence suggests WISP-1 mediates its downstream effects by binding to integrins. Here we describe a functional analysis of integrin receptor usage by WISP-1. Truncated WISP-1 proteins were produced using a baculovirus expression system. Full length WISP-1 and truncated proteins were evaluated for their ability to induce adhesion in A549 epithelial cells and β-catenin activation and CXCL3 secretion in fibroblasts (NRK49-F cells). Subsequent inhibition of these responses by neutralising integrin antibodies was evaluated. A549 cells demonstrated adhesion to full-length WISP-1 whilst truncated proteins containing VWC, TSP or CT domains also induced adhesion, with highest activity observed with proteins containing the C-terminal TSP and CT domains. Likewise the ability to induce β-catenin activation and CXCL3 secretion was retained in truncations containing C-terminal domains. Pre-treatment of A549s with either integrin αVβ5, αVβ3 or β1 neutralising antibodies partially inhibited full length WISP-1 induced adhesion whilst combining integrin αVβ5 and β1 antibodies increased the potency of this effect. Incubation of NRK49-F cells with integrin neutralising antibodies failed to effect β-catenin translocation or CXCL3 secretion. Analysis of natural WISP-1 derived from human lung tissue showed the native protein is a high order oligomer. Our data suggest that WISP-1 mediated adhesion of A549 cells is an integrin-driven event regulated by the C-terminal domains of the protein. Activation of β-catenin signalling and CXCL3 secretion also resides within the C-terminal domains of WISP-1 but are not regulated by integrins. The oligomeric nature of native

  5. Feasibility of 68Ga-labeled Siglec-9 peptide for the imaging of acute lung inflammation: a pilot study in a porcine model of acute respiratory distress syndrome

    PubMed Central

    Retamal, Jaime; Sörensen, Jens; Lubberink, Mark; Suarez-Sipmann, Fernando; Borges, João Batista; Feinstein, Ricardo; Jalkanen, Sirpa; Antoni, Gunnar; Hedenstierna, Göran; Roivainen, Anne; Larsson, Anders; Velikyan, Irina

    2016-01-01

    There is an unmet need for noninvasive, specific and quantitative imaging of inherent inflammatory activity. Vascular adhesion protein-1 (VAP-1) translocates to the luminal surface of endothelial cells upon inflammatory challenge. We hypothesized that in a porcine model of acute respiratory distress syndrome (ARDS), positron emission tomography (PET) with sialic acid-binding immunoglobulin-like lectin 9 (Siglec-9) based imaging agent targeting VAP-1 would allow quantification of regional pulmonary inflammation. ARDS was induced by lung lavages and injurious mechanical ventilation. Hemodynamics, respiratory system compliance (Crs) and blood gases were monitored. Dynamic examination using [15O]water PET-CT (10 min) was followed by dynamic (90 min) and whole-body examination using VAP-1 targeting 68Ga-labeled 1,4,7,10-tetraaza cyclododecane-1,4,7-tris-acetic acid-10-ethylene glycol-conjugated Siglec-9 motif peptide ([68Ga]Ga-DOTA-Siglec-9). The animals received an anti-VAP-1 antibody for post-mortem immunohistochemistry assay of VAP-1 receptors. Tissue samples were collected post-mortem for the radioactivity uptake, histology and immunohistochemistry assessment. Marked reduction of oxygenation and Crs, and higher degree of inflammation were observed in ARDS animals. [68Ga]Ga-DOTA-Siglec-9 PET showed significant uptake in lungs, kidneys and urinary bladder. Normalization of the net uptake rate (Ki) for the tissue perfusion resulted in 4-fold higher uptake rate of [68Ga]Ga-DOTA-Siglec-9 in the ARDS lungs. Immunohistochemistry showed positive VAP-1 signal in the injured lungs. Detection of pulmonary inflammation associated with a porcine model of ARDS was possible with [68Ga]Ga-DOTA-Siglec-9 PET when using kinetic modeling and normalization for tissue perfusion. PMID:27069763

  6. Feasibility of (68)Ga-labeled Siglec-9 peptide for the imaging of acute lung inflammation: a pilot study in a porcine model of acute respiratory distress syndrome.

    PubMed

    Retamal, Jaime; Sörensen, Jens; Lubberink, Mark; Suarez-Sipmann, Fernando; Borges, João Batista; Feinstein, Ricardo; Jalkanen, Sirpa; Antoni, Gunnar; Hedenstierna, Göran; Roivainen, Anne; Larsson, Anders; Velikyan, Irina

    2016-01-01

    There is an unmet need for noninvasive, specific and quantitative imaging of inherent inflammatory activity. Vascular adhesion protein-1 (VAP-1) translocates to the luminal surface of endothelial cells upon inflammatory challenge. We hypothesized that in a porcine model of acute respiratory distress syndrome (ARDS), positron emission tomography (PET) with sialic acid-binding immunoglobulin-like lectin 9 (Siglec-9) based imaging agent targeting VAP-1 would allow quantification of regional pulmonary inflammation. ARDS was induced by lung lavages and injurious mechanical ventilation. Hemodynamics, respiratory system compliance (Crs) and blood gases were monitored. Dynamic examination using [(15)O]water PET-CT (10 min) was followed by dynamic (90 min) and whole-body examination using VAP-1 targeting (68)Ga-labeled 1,4,7,10-tetraaza cyclododecane-1,4,7-tris-acetic acid-10-ethylene glycol-conjugated Siglec-9 motif peptide ([(68)Ga]Ga-DOTA-Siglec-9). The animals received an anti-VAP-1 antibody for post-mortem immunohistochemistry assay of VAP-1 receptors. Tissue samples were collected post-mortem for the radioactivity uptake, histology and immunohistochemistry assessment. Marked reduction of oxygenation and Crs, and higher degree of inflammation were observed in ARDS animals. [(68)Ga]Ga-DOTA-Siglec-9 PET showed significant uptake in lungs, kidneys and urinary bladder. Normalization of the net uptake rate (Ki) for the tissue perfusion resulted in 4-fold higher uptake rate of [(68)Ga]Ga-DOTA-Siglec-9 in the ARDS lungs. Immunohistochemistry showed positive VAP-1 signal in the injured lungs. Detection of pulmonary inflammation associated with a porcine model of ARDS was possible with [(68)Ga]Ga-DOTA-Siglec-9 PET when using kinetic modeling and normalization for tissue perfusion. PMID:27069763

  7. Thrombin Cleavage of Plasmodium falciparum Erythrocyte Membrane Protein 1 Inhibits Cytoadherence

    PubMed Central

    Gillrie, Mark R.; Renaux, Bernard; Russell-Goldman, Eleanor; Avril, Marion; Brazier, Andrew J.; Mihara, Koichiro; Di Cera, Enrico; Milner, Danny A.; Hollenberg, Morley D.; Smith, Joseph D.

    2016-01-01

    ABSTRACT Plasmodium falciparum malaria remains one of the most deadly infections worldwide. The pathogenesis of the infection results from the sequestration of infected erythrocytes (IRBC) in vital organs, including the brain, with resulting impairment of blood flow, hypoxia, and lactic acidosis. Sequestration occurs through the adhesion of IRBC to host receptors on microvascular endothelium by Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a large family of variant surface antigens, each with up to seven extracellular domains that can bind to multiple host receptors. Consequently, antiadhesive therapies directed at single endothelial adhesion molecules may not be effective. In this study, we demonstrated that the serine protease thrombin, which is pivotal in the activation of the coagulation cascade, cleaved the major parasite adhesin on the surface of IRBC. As a result, adhesion under flow was dramatically reduced, and already adherent IRBC were detached. Thrombin cleavage sites were mapped to the Duffy binding-like δ1 (DBLδ1) domain and interdomains 1 and 2 in the PfEMP1 of the parasite line IT4var19. Furthermore, we observed an inverse correlation between the presence of thrombin and IRBC in cerebral malaria autopsies of children. We investigated a modified (R67A) thrombin and thrombin inhibitor, hirugen, both of which inhibit the binding of substrates to exosite I, thereby reducing its proinflammatory properties. Both approaches reduced the barrier dysfunction induced by thrombin without affecting its proteolytic activity on PfEMP1, raising the possibility that thrombin cleavage of variant PfEMP1 may be exploited as a broadly inhibitory antiadhesive therapy. PMID:27624125

  8. Optical adhesive property study

    SciTech Connect

    Sundvold, P.D.

    1996-01-01

    Tests were performed to characterize the mechanical and thermal properties of selected optical adhesives to identify the most likely candidate which could survive the operating environment of the Direct Optical Initiation (DOI) program. The DOI system consists of a high power laser and an optical module used to split the beam into a number of channels to initiate the system. The DOI requirements are for a high shock environment which current military optical systems do not operate. Five candidate adhesives were selected and evaluated using standardized test methods to determine the adhesives` physical properties. EC2216, manufactured by 3M, was selected as the baseline candidate adhesive based on the test results of the physical properties.

  9. Adhesion of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.

    2007-01-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  10. Adhesives for Aerospace

    NASA Technical Reports Server (NTRS)

    Meade, L. E.

    1985-01-01

    The industry is hereby challenged to integrate adhesive technology with the total structure requirements in light of today's drive into automation/mechanization. The state of the art of adhesive technology is fairly well meeting the needs of the structural designers, the processing engineer, and the inspector, each on an individual basis. The total integration of these needs into the factory of the future is the next collective hurdle to be achieved. Improved processing parameters to fit the needs of automation/mechanization will necessitate some changes in the adhesive forms, formulations, and chemistries. Adhesives have, for the most part, kept up with the needs of the aerospace industry, normally leading the rest of the industry in developments. The wants of the aerospace industry still present a challenge to encompass all elements, achieving a totally integrated joined and sealed structural system. Better toughness with hot-wet strength improvements is desired. Lower cure temperatures, longer out times, and improved corrosion inhibition are desired.

  11. Mussel foot protein-1 (mcfp-1) interaction with titania surfaces†

    PubMed Central

    Harrington, Matthew J.; Lu, Qingye; Masic, Admir

    2012-01-01

    Marine mussels utilize a variety of DOPA-rich proteins for purposes of underwater adhesion, as well as for creating hard and flexible surface coatings for their tough and stretchy byssal fibers. In the present study, moderately strong, yet reversible wet adhesion between the protective mussel coating protein, mcfp-1, and amorphous titania was measured with a surface force apparatus (SFA). In parallel, resonance Raman spectroscopy was employed to identify the presence of bidentate DOPA–Ti coordination bonds at the TiO2–protein interface, suggesting that catechol–TiO2 complexation contributes to the observed reversible wet adhesion. These results have important implications for the design of protective coatings on TiO2. PMID:23100857

  12. Dry adhesives with sensing features

    NASA Astrophysics Data System (ADS)

    Krahn, J.; Menon, C.

    2013-08-01

    Geckos are capable of detecting detachment of their feet. Inspired by this basic observation, a novel functional dry adhesive is proposed, which can be used to measure the instantaneous forces and torques acting on an adhesive pad. Such a novel sensing dry adhesive could potentially be used by climbing robots to quickly realize and respond appropriately to catastrophic detachment conditions. The proposed torque and force sensing dry adhesive was fabricated by mixing Carbon Black (CB) and Polydimethylsiloxane (PDMS) to form a functionalized adhesive with mushroom caps. The addition of CB to PDMS resulted in conductive PDMS which, when under compression, tension or torque, resulted in a change in the resistance across the adhesive patch terminals. The proposed design of the functionalized dry adhesive enables distinguishing an applied torque from a compressive force in a single adhesive pad. A model based on beam theory was used to predict the change in resistance across the terminals as either a torque or compressive force was applied to the adhesive patch. Under a compressive force, the sensing dry adhesive was capable of measuring compression stresses from 0.11 Pa to 20.9 kPa. The torque measured by the adhesive patch ranged from 2.6 to 10 mN m, at which point the dry adhesives became detached. The adhesive strength was 1.75 kPa under an applied preload of 1.65 kPa for an adhesive patch with an adhesive contact area of 7.07 cm2.

  13. Magnetic field switchable dry adhesives.

    PubMed

    Krahn, Jeffrey; Bovero, Enrico; Menon, Carlo

    2015-02-01

    A magnetic field controllable dry adhesive device is manufactured. The normal adhesion force can be increased or decreased depending on the presence of an applied magnetic field. If the magnetic field is present during the entire normal adhesion test cycle which includes both applying a preloading force and measuring the pulloff pressure, a decrease in adhesion is observed when compared to when there is no applied magnetic field. Similarly, if the magnetic field is present only during the preload portion of the normal adhesion test cycle, a decrease in adhesion is observed because of an increased stiffness of the magnetically controlled dry adhesive device. When the applied magnetic field is present during only the pulloff portion of the normal adhesion test cycle, either an increase or a decrease in normal adhesion is observed depending on the direction of the applied magnetic field.

  14. Regulation of Cell Adhesion Strength by Peripheral Focal Adhesion Distribution

    PubMed Central

    Elineni, Kranthi Kumar; Gallant, Nathan D.

    2011-01-01

    Cell adhesion to extracellular matrices is a tightly regulated process that involves the complex interplay between biochemical and mechanical events at the cell-adhesive interface. Previous work established the spatiotemporal contributions of adhesive components to adhesion strength and identified a nonlinear dependence on cell spreading. This study was designed to investigate the regulation of cell-adhesion strength by the size and position of focal adhesions (FA). The cell-adhesive interface was engineered to direct FA assembly to the periphery of the cell-spreading area to delineate the cell-adhesive area from the cell-spreading area. It was observed that redistributing the same adhesive area over a larger cell-spreading area significantly enhanced cell-adhesion strength, but only up to a threshold area. Moreover, the size of the peripheral FAs, which was interpreted as an adhesive patch, did not directly govern the adhesion strength. Interestingly, this is in contrast to the previously reported functional role of FAs in regulating cellular traction where sizes of the peripheral FAs play a critical role. These findings demonstrate, to our knowledge for the first time, that two spatial regimes in cell-spreading area exist that uniquely govern the structure-function role of FAs in regulating cell-adhesion strength. PMID:22208188

  15. Adhesive particle shielding

    DOEpatents

    Klebanoff, Leonard Elliott; Rader, Daniel John; Walton, Christopher; Folta, James

    2009-01-06

    An efficient device for capturing fast moving particles has an adhesive particle shield that includes (i) a mounting panel and (ii) a film that is attached to the mounting panel wherein the outer surface of the film has an adhesive coating disposed thereon to capture particles contacting the outer surface. The shield can be employed to maintain a substantially particle free environment such as in photolithographic systems having critical surfaces, such as wafers, masks, and optics and in the tools used to make these components, that are sensitive to particle contamination. The shield can be portable to be positioned in hard-to-reach areas of a photolithography machine. The adhesive particle shield can incorporate cooling means to attract particles via the thermophoresis effect.

  16. Natural Underwater Adhesives

    PubMed Central

    Stewart, Russell J.; Ransom, Todd C.; Hlady, Vladimir

    2011-01-01

    The general topic of this review is protein-based underwater adhesives produced by aquatic organisms. The focus is on mechanisms of interfacial adhesion to native surfaces and controlled underwater solidification of natural water-borne adhesives. Four genera that exemplify the broad range of function, general mechanistic features, and unique adaptations are discussed in detail: blue mussels, acorn barnacles, sandcastle worms, and freshwater caddisfly larva. Aquatic surfaces in nature are charged and in equilibrium with their environment, populated by an electrical double layer of ions as well as adsorbed natural polyelectrolytes and microbial biofilms. Surface adsorption of underwater bioadhesives likely occurs by exchange of surface bound ligands by amino acid sidechains, driven primarily by relative affinities and effective concentrations of polymeric functional groups. Most aquatic organisms exploit modified amino acid sidechains, in particular phosphorylated serines and hydroxylated tyrosines (dopa), with high-surface affinity that form coordinative surface complexes. After delivery to the surfaces as a fluid, permanent natural adhesives solidify to bear sustained loads. Mussel plaques are assembled in a manner superficially reminiscent of in vitro layer-by-layer strategies, with sequentially delivered layers associated through Fe(dopa)3 coordination bonds. The adhesives of sandcastle worms, caddisfly larva, and barnacles may be delivered in a form somewhat similar to in vitro complex coacervation. Marine adhesives are secreted, or excreted, into seawater that has a significantly higher pH and ionic strength than the internal environment. Empirical evidence suggests these environment triggers could provide minimalistic, fail-safe timing mechanisms to prevent premature solidification (insolubilization) of the glue within the secretory system, yet allow rapid solidification after secretion. Underwater bioadhesives are further strengthened by secondary covalent

  17. Sphingosylphosphorylcholine inhibits macrophage adhesion to vascular smooth muscle cells.

    PubMed

    Wirrig, Christiane; McKean, Jenny S; Wilson, Heather M; Nixon, Graeme F

    2016-09-01

    Inflammation in de-endothelialised arteries contributes to the development of cardiovascular diseases. The process that initiates this inflammatory response is the adhesion of monocytes/macrophages to exposed vascular smooth muscle cells, typically stimulated by cytokines such as tumour necrosis factor-α (TNF). The aim of this study was to determine the effect of the sphingolipid sphingosylphosphorylcholine (SPC) on the interaction of monocytes/macrophages with vascular smooth muscle cells. Rat aortic smooth muscle cells and rat bone marrow-derived macrophages were co-cultured using an in vitro assay following incubation with sphingolipids to assess inter-cellular adhesion. We reveal that SPC inhibits the TNF-induced adhesion of macrophages to smooth muscle cells. This anti-adhesive effect was the result of SPC-induced changes to the smooth muscle cells (but not the macrophages) and was mediated, at least partly, via the sphingosine 1-phosphate receptor subtype 2. Lipid raft domains were also required. Although SPC did not alter expression or membrane distribution of the adhesion proteins intercellular adhesion molecule-1 and vascular cellular adhesion protein-1 in smooth muscle cells, SPC preincubation inhibited the TNF-induced increase in inducible nitric oxide synthase (NOS2) resulting in a subsequent decrease in nitric oxide production. Inhibiting NOS2 activation in smooth muscle cells led to a decrease in the adhesion of macrophages to smooth muscle cells. This study has therefore delineated a novel pathway which can inhibit the interaction between macrophages and vascular smooth muscle cells via SPC-induced repression of NOS2 expression. This mechanism could represent a potential drug target in vascular disease.

  18. Sphingosylphosphorylcholine inhibits macrophage adhesion to vascular smooth muscle cells.

    PubMed

    Wirrig, Christiane; McKean, Jenny S; Wilson, Heather M; Nixon, Graeme F

    2016-09-01

    Inflammation in de-endothelialised arteries contributes to the development of cardiovascular diseases. The process that initiates this inflammatory response is the adhesion of monocytes/macrophages to exposed vascular smooth muscle cells, typically stimulated by cytokines such as tumour necrosis factor-α (TNF). The aim of this study was to determine the effect of the sphingolipid sphingosylphosphorylcholine (SPC) on the interaction of monocytes/macrophages with vascular smooth muscle cells. Rat aortic smooth muscle cells and rat bone marrow-derived macrophages were co-cultured using an in vitro assay following incubation with sphingolipids to assess inter-cellular adhesion. We reveal that SPC inhibits the TNF-induced adhesion of macrophages to smooth muscle cells. This anti-adhesive effect was the result of SPC-induced changes to the smooth muscle cells (but not the macrophages) and was mediated, at least partly, via the sphingosine 1-phosphate receptor subtype 2. Lipid raft domains were also required. Although SPC did not alter expression or membrane distribution of the adhesion proteins intercellular adhesion molecule-1 and vascular cellular adhesion protein-1 in smooth muscle cells, SPC preincubation inhibited the TNF-induced increase in inducible nitric oxide synthase (NOS2) resulting in a subsequent decrease in nitric oxide production. Inhibiting NOS2 activation in smooth muscle cells led to a decrease in the adhesion of macrophages to smooth muscle cells. This study has therefore delineated a novel pathway which can inhibit the interaction between macrophages and vascular smooth muscle cells via SPC-induced repression of NOS2 expression. This mechanism could represent a potential drug target in vascular disease. PMID:27402344

  19. Elastomer toughened polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L. (Inventor)

    1983-01-01

    A rubber-toughened addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state, and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride was mixed, and utilizing solvent or mixture of solvents for the reaction.

  20. Adhesion in hydrogel contacts

    NASA Astrophysics Data System (ADS)

    Torres, J. R.; Jay, G. D.; Kim, K.-S.; Bothun, G. D.

    2016-05-01

    A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.

  1. Switchable bio-inspired adhesives

    NASA Astrophysics Data System (ADS)

    Kroner, Elmar

    2015-03-01

    Geckos have astonishing climbing abilities. They can adhere to almost any surface and can run on walls and even stick to ceilings. The extraordinary adhesion performance is caused by a combination of a complex surface pattern on their toes and the biomechanics of its movement. These biological dry adhesives have been intensely investigated during recent years because of the unique combination of adhesive properties. They provide high adhesion, allow for easy detachment, can be removed residue-free, and have self-cleaning properties. Many aspects have been successfully mimicked, leading to artificial, bio-inspired, patterned dry adhesives, and were addressed and in some aspects they even outperform the adhesion capabilities of geckos. However, designing artificial patterned adhesion systems with switchable adhesion remains a big challenge; the gecko's adhesion system is based on a complex hierarchical surface structure and on advanced biomechanics, which are both difficult to mimic. In this paper, two approaches are presented to achieve switchable adhesion. The first approach is based on a patterned polydimethylsiloxane (PDMS) polymer, where adhesion can be switched on and off by applying a low and a high compressive preload. The switch in adhesion is caused by a reversible mechanical instability of the adhesive silicone structures. The second approach is based on a composite material consisting of a Nickel- Titanium (NiTi) shape memory alloy and a patterned adhesive PDMS layer. The NiTi alloy is trained to change its surface topography as a function of temperature, which results in a change of the contact area and of alignment of the adhesive pattern towards a substrate, leading to switchable adhesion. These examples show that the unique properties of bio-inspired adhesives can be greatly improved by new concepts such as mechanical instability or by the use of active materials which react to external stimuli.

  2. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects.

  3. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives

    PubMed Central

    2015-01-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm2 provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  4. Switchable Adhesion in Vacuum Using Bio-Inspired Dry Adhesives.

    PubMed

    Purtov, Julia; Frensemeier, Mareike; Kroner, Elmar

    2015-11-01

    Suction based attachment systems for pick and place handling of fragile objects like glass plates or optical lenses are energy-consuming and noisy and fail at reduced air pressure, which is essential, e.g., in chemical and physical vapor deposition processes. Recently, an alternative approach toward reversible adhesion of sensitive objects based on bioinspired dry adhesive structures has emerged. There, the switching in adhesion is achieved by a reversible buckling of adhesive pillar structures. In this study, we demonstrate that these adhesives are capable of switching adhesion not only in ambient air conditions but also in vacuum. Our bioinspired patterned adhesive with an area of 1 cm(2) provided an adhesion force of 2.6 N ± 0.2 N in air, which was reduced to 1.9 N ± 0.2 N if measured in vacuum. Detachment was induced by buckling of the structures due to a high compressive preload and occurred, independent of air pressure, at approximately 0.9 N ± 0.1 N. The switch in adhesion was observed at a compressive preload between 5.6 and 6.0 N and was independent of air pressure. The difference between maximum adhesion force and adhesion force after buckling gives a reasonable window of operation for pick and place processes. High reversibility of the switching behavior is shown over 50 cycles in air and in vacuum, making the bioinspired switchable adhesive applicable for handling operations of fragile objects. PMID:26457864

  5. Wood Composite Adhesives

    NASA Astrophysics Data System (ADS)

    Gomez-Bueso, Jose; Haupt, Robert

    The global environment, in which phenolic resins are being used for wood composite manufacture, has changed significantly during the last decade. This chapter reviews trends that are driving the use and consumption of phenolic resins around the world. The review begins with recent data on volume usage and regional trends, followed by an analysis of factors affecting global markets. In a section on environmental factors, the impact of recent formaldehyde emission regulations is discussed. The section on economics introduces wood composite production as it relates to the available adhesive systems, with special emphasis on the technical requirement to improve phenolic reactivity. Advances in composite process technology are introduced, especially in regard to the increased demands the improvements place upon adhesive system performance. The specific requirements for the various wood composite families are considered in the context of adhesive performance needs. The results of research into current chemistries are discussed, with a review of recent findings regarding the mechanisms of phenolic condensation and acceleration. Also, the work regarding alternate natural materials, such as carbohydrates, lignins, tannins, and proteinaceous materials, is presented. Finally, new developments in alternative adhesive technologies are reported.

  6. Rapid adhesive bonding concepts

    NASA Technical Reports Server (NTRS)

    Stein, B. A.; Tyeryar, J. R.; Hodges, W. T.

    1984-01-01

    Adhesive bonding in the aerospace industry typically utilizes autoclaves or presses which have considerable thermal mass. As a consequence, the rates of heatup and cooldown of the bonded parts are limited and the total time and cost of the bonding process is often relatively high. Many of the adhesives themselves do not inherently require long processing times. Bonding could be performed rapidly if the heat was concentrated in the bond lines or at least in the adherends. Rapid adhesive bonding concepts were developed to utilize induction heating techniques to provide heat directly to the bond line and/or adherends without heating the entire structure, supports, and fixtures of a bonding assembly. Bonding times for specimens are cut by a factor of 10 to 100 compared to standard press bonding. The development of rapid adhesive bonding for lap shear specimens (per ASTM D1003 and D3163), for aerospace panel bonding, and for field repair needs of metallic and advanced fiber reinforced polymeric matrix composite structures are reviewed.

  7. Resistance heating releases structural adhesive

    NASA Technical Reports Server (NTRS)

    Glemser, N. N.

    1967-01-01

    Composite adhesive package bonds components together for testing and enables separation when testing is completed. The composite of adhesives, insulation and a heating element separate easily when an electrical current is applied.

  8. 3-D foam adhesive deposition

    NASA Technical Reports Server (NTRS)

    Lemons, C. R.; Salmassy, O. K.

    1976-01-01

    Bonding method, which reduces amount and weight of adhesive, is applicable to foam-filled honeycomb constructions. Novel features of process include temperature-viscosity control and removal of excess adhesive by transfer to cellophane film.

  9. Coating Reduces Ice Adhesion

    NASA Technical Reports Server (NTRS)

    Smith, Trent; Prince, Michael; DwWeese, Charles; Curtis, Leslie

    2008-01-01

    The Shuttle Ice Liberation Coating (SILC) has been developed to reduce the adhesion of ice to surfaces on the space shuttle. SILC, when coated on a surface (foam, metal, epoxy primer, polymer surfaces), will reduce the adhesion of ice by as much as 90 percent as compared to the corresponding uncoated surface. This innovation is a durable coating that can withstand several cycles of ice growth and removal without loss of anti-adhesion properties. SILC is made of a binder composed of varying weight percents of siloxane(s), ethyl alcohol, ethyl sulfate, isopropyl alcohol, and of fine-particle polytetrafluoroethylene (PTFE). The combination of these components produces a coating with significantly improved weathering characteristics over the siloxane system alone. In some cases, the coating will delay ice formation and can reduce the amount of ice formed. SILC is not an ice prevention coating, but the very high water contact angle (greater than 140 ) causes water to readily run off the surface. This coating was designed for use at temperatures near -170 F (-112 C). Ice adhesion tests performed at temperatures from -170 to 20 F (-112 to -7 C) show that SILC is a very effective ice release coating. SILC can be left as applied (opaque) or buffed off until the surface appears clear. Energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS) data show that the coating is still present after buffing to transparency. This means SILC can be used to prevent ice adhesion even when coating windows or other objects, or items that require transmission of optical light. Car windshields are kept cleaner and SILC effectively mitigates rain and snow under driving conditions.

  10. Adhesion behaviors on superhydrophobic surfaces.

    PubMed

    Zhu, Huan; Guo, Zhiguang; Liu, Weimin

    2014-04-18

    The adhesion behaviors of superhydrophobic surfaces have become an emerging topic to researchers in various fields as a vital step in the interactions between materials and organisms/materials. Controlling the chemical compositions and topological structures via various methods or technologies is essential to fabricate and modulate different adhesion properties, such as low-adhesion, high-adhesion and anisotropic adhesion on superhydrophobic surfaces. We summarize the recent developments in both natural superhydrophobic surfaces and artificial superhydrophobic surfaces with various adhesions and also pay attention to superhydrophobic surfaces switching between low- and high-adhesion. The methods to regulate or translate the adhesion of superhydrophobic surfaces can be considered from two perspectives. One is to control the chemical composition and change the surface geometric structure on the surfaces, respectively or simultaneously. The other is to provide external stimulations to induce transitions, which is the most common method for obtaining switchable adhesions. Additionally, adhesion behaviors on solid-solid interfaces, such as the behaviors of cells, bacteria, biomolecules and icing on superhydrophobic surfaces are also noticeable and controversial. This review is aimed at giving a brief and crucial overview of adhesion behaviors on superhydrophobic surfaces.

  11. Environmentally compliant adhesive joining technology

    SciTech Connect

    Tira, J.S.

    1996-08-01

    Adhesive joining offers one method of assembling products. Advantages of adhesive joining/assembly include distribution of applied forces, lighter weight, appealing appearance, etc. Selecting environmentally safe adhesive materials and accompanying processes is paramount in today`s business climate if a company wants to be environmentally conscious and stay in business. Four areas of adhesive joining (adhesive formulation and selection, surface preparation, adhesive bonding process, waste and pollution generation/cleanup/management) all need to be carefully evaluated before adhesive joining is selected for commercial as well as military products. Designing for six sigma quality must also be addressed in today`s global economy. This requires material suppliers and product manufacturers to work even closer together.

  12. Ceramic microstructure and adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1985-01-01

    When a ceramic is brought into contact with a ceramic, a polymer, or a metal, strong bond forces can develop between the materials. The bonding forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between a ceramic and another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to interface resulting from solid state contact. Surface properties of ceramics correlated with adhesion include, orientation, reconstruction and diffusion as well as the chemistry of the surface specie. Where a ceramic is in contact with a metal their interactive chemistry and bond strength is considered. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structures and crystallographic orientation. Materials examined with respect to interfacial adhesive interactions include silicon carbide, nickel zinc ferrite, manganese zinc ferrite, and aluminum oxide. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  13. Development of phosphorylated adhesives

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Giants, T. W.; Jenkins, R. K.; Campbell, P. L.

    1983-01-01

    The synthesis of epoxy prepolymers containing phosphorus was carried out in such a manner as to provide adhesives containing at least 5 percent of this element. The purpose of this was to impart fire retardant properties to the adhesive. The two epoxy derivatives, bis(4-glycidyl-oxyphenyl)phenylphosphine oxide and bis(4-glycidyl-2-methoxyphenyl)phenylphosphonate, and a curing agent, bis(3-aminophenyl)methylphosphine oxide, were used in conjunction with one another and along with conventional epoxy resins and curing agents to bond Tedlar and Polyphenylethersulfone films to Kerimid-glass syntactic foam-filled honeycomb structures. Elevated temperatures are required to cure the epoxy resins with the phosphorus-contaning diamine; however, when Tedlar is being bonded, lower curing temperatures must be used to avoid shrinkage and the concomitant formation of surface defects. Thus, the phosphorus-containing aromatic amine curing agent cannot be used alone, although it is possible to use it in conjunction with an aliphatic amine which would allow lower cure temperatures to be used. The experimental epoxy resins have not provided adhesive bonds quite as strong as those provided by Epon 828 when compared in peel tests, but the differences are not very significant. It should be noted, if optimum properties are to be realized. In any case the fire retardant characteristics of the neat resin systems obtained are quite pronounced, since in most cases the self-extinguishing properties are evident almost instantly when specimens are removed from a flame.

  14. Ceramic microstructure and adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When a ceramic is brought into contact with a ceramic, a polymer, or a metal, strong bond forces can develop between the materials. The bonding forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between a ceramic and another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to interface resulting from solid state contact. Surface properties of ceramics correlated with adhesion include, orientation, reconstruction and diffusion as well as the chemistry of the surface specie. Where a ceramic is in contact with a metal their interactive chemistry and bond strength is considered. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structures and crystallographic orientation. Materials examined with respect to interfacial adhesive interactions include silicon carbide, nickel zinc ferrite, manganese zinc ferrite, and aluminum oxide. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  15. Adhesion barrier reduces postoperative adhesions after cardiac surgery.

    PubMed

    Kaneko, Yukihiro; Hirata, Yasutaka; Achiwa, Ikuya; Morishita, Hiroyuki; Soto, Hajime; Kobayahsi, Jotaro

    2012-06-01

    Reoperation in cardiac surgery is associated with increased risk due to surgical adhesions. Application of a bioresorbable material could theoretically reduce adhesions and allow later development of a free dissection plane for cardiac reoperation. Twenty-one patients in whom a bioresorbable hyaluronic acid-carboxymethylcellulose adhesion barrier had been applied in a preceding surgery underwent reoperations, while 23 patients underwent reoperations during the same period without a prior adhesion barrier. Blinded observers graded the tenacity of the adhesions from surgical video recordings of the reoperations. No excessive bleeding requiring wound reexploration, mediastinal infection, or other complication attributable to the adhesion barrier occurred. Multiple regression analysis showed that shorter duration of the preceding surgery, non-use of cardiopulmonary bypass in the preceding surgery, and use of the adhesion barrier were significantly associated with less tenacious surgical adhesions. The use of a bioresorbable material in cardiac surgery reduced postoperative adhesions, facilitated reoperation, and did not promote complications. The use of adhesion barrier is recommended in planned staged procedures and those in which future reoperation is likely.

  16. Monocyte Chemoattractant Protein 1 (MCP-1) in Obesity and Diabetes

    PubMed Central

    Panee, Jun

    2012-01-01

    Monocyte chemoattractant protein-1 (MCP-1) is the first discovered and most extensively studied CC chemokine, and the amount of studies on its role in the etiologies of obesity- and diabetes-related diseases have increased exponentially during the past 2 decades. This review attempted to provide a panoramic perspective of the history, regulatory mechanisms, functions, and therapeutic strategies of this chemokine. The highlights of this review include the roles of MCP-1 in the development of obesity, diabetes, cardiovascular diseases, insulitis, diabetic nephropathy, and diabetic retinopathy. Therapies that specifically or non-specifically inhibit MCP-1 overproduction have been summarized. PMID:22766373

  17. Nonstructural Protein 1 of Influenza A Virus Interacts with Human Guanylate-Binding Protein 1 to Antagonize Antiviral Activity

    PubMed Central

    Yan, Wenjun; Wei, Jianchao; Shao, Donghua; Deng, Xufang; Wang, Shaohui; Li, Beibei; Tong, Guangzhi; Ma, Zhiyong

    2013-01-01

    Human guanylate-binding protein 1 (hGBP1) is an interferon-inducible protein involved in the host immune response against viral infection. In response to infection by influenza A virus (IAV), hGBP1 transcript and protein were significantly upregulated. Overexpression of hGBP1 inhibited IAV replication in a dose-dependent manner in vitro. The lysine residue at position 51 (K51) of hGBP1 was essential for inhibition of IAV replication. Mutation of K51 resulted in an hGBP1 that was unable to inhibit IAV replication. The viral nonstructural protein 1 (NS1) was found to interact directly with hGBP1. K51 of hGBP1 and a region between residues 123 and 144 in NS1 were demonstrated to be essential for the interaction between NS1 and hGBP1. Binding of NS1 to hGBP1 resulted in a significant reduction in both GTPase activity and the anti-IAV activity of hGBP1. These findings indicated that hGBP1 contributed to the host immune response against IAV replication and that hGBP1-mediated antiviral activity was antagonized by NS1 via binding to hGBP1. PMID:23405236

  18. Nonstructural protein 1 of influenza A virus interacts with human guanylate-binding protein 1 to antagonize antiviral activity.

    PubMed

    Zhu, Zixiang; Shi, Zixue; Yan, Wenjun; Wei, Jianchao; Shao, Donghua; Deng, Xufang; Wang, Shaohui; Li, Beibei; Tong, Guangzhi; Ma, Zhiyong

    2013-01-01

    Human guanylate-binding protein 1 (hGBP1) is an interferon-inducible protein involved in the host immune response against viral infection. In response to infection by influenza A virus (IAV), hGBP1 transcript and protein were significantly upregulated. Overexpression of hGBP1 inhibited IAV replication in a dose-dependent manner in vitro. The lysine residue at position 51 (K51) of hGBP1 was essential for inhibition of IAV replication. Mutation of K51 resulted in an hGBP1 that was unable to inhibit IAV replication. The viral nonstructural protein 1 (NS1) was found to interact directly with hGBP1. K51 of hGBP1 and a region between residues 123 and 144 in NS1 were demonstrated to be essential for the interaction between NS1 and hGBP1. Binding of NS1 to hGBP1 resulted in a significant reduction in both GTPase activity and the anti-IAV activity of hGBP1. These findings indicated that hGBP1 contributed to the host immune response against IAV replication and that hGBP1-mediated antiviral activity was antagonized by NS1 via binding to hGBP1.

  19. [Adhesive cutaneous pharmaceutical forms].

    PubMed

    Gafiţanu, E; Matei, I; Mungiu, O C; Pavelescu, M; Mîndreci, I; Apostol, I; Ionescu, G

    1989-01-01

    The adhesive cutaneous pharmaceutical forms aimed to local action release the drug substance in view of a dermatological, traumatological, antirheumatic, cosmetic action. Two such preparations were obtained and their stability, consistency and pH were determined. The "in vitro" tests of their bioavailability revealed the dynamics of calcium ions release according to the associations of each preparation. The bioavailability determined by evaluating the pharmacological response demonstrated the antiinflammatory action obtained by the association of calcium ions with the components extracted from poplar muds. The therapeutical efficiency of the studied preparations has proved in the treatment of some sport injuries.

  20. Molecular energy dissipation in nanoscale networks of Dentin Matrix Protein 1 is strongly dependent on ion valence

    PubMed Central

    Adams, J; Fantner, G E; Fisher, L W; Hansma, P K

    2008-01-01

    The fracture resistance of biomineralized tissues such as bone, dentin, and abalone is greatly enhanced through the nanoscale interactions of stiff inorganic mineral components with soft organic adhesive components. A proper understanding of the interactions that occur within the organic component, and between the organic and inorganic components, is therefore critical for a complete understanding of the mechanics of these tissues. In this paper, we use Atomic Force Microscope (AFM) force spectroscopy and dynamic force spectroscopy to explore the effect of ionic interactions within a nanoscale system consisting of networks of Dentin Matrix Protein 1 (DMP1) (a component of both bone and dentin organic matrix), a mica surface, and an AFM tip. We find that DMP1 is capable of dissipating large amounts of energy through an ion-mediated mechanism, and that the effectiveness increases with increasing ion valence. PMID:18843380

  1. Molecular energy dissipation in nanoscale networks of dentin matrix protein 1 is strongly dependent on ion valence

    NASA Astrophysics Data System (ADS)

    Adams, J.; Fantner, G. E.; Fisher, L. W.; Hansma, P. K.

    2008-09-01

    The fracture resistance of biomineralized tissues such as bone, dentin, and abalone is greatly enhanced through the nanoscale interactions of stiff inorganic mineral components with soft organic adhesive components. A proper understanding of the interactions that occur within the organic component, and between the organic and inorganic components, is therefore critical for a complete understanding of the mechanics of these tissues. In this paper, we use atomic force microscope (AFM) force spectroscopy and dynamic force spectroscopy to explore the effect of ionic interactions within a nanoscale system consisting of networks of dentin matrix protein 1 (DMP1) (a component of both bone and dentin organic matrix), a mica surface and an AFM tip. We find that DMP1 is capable of dissipating large amounts of energy through an ion-mediated mechanism, and that the effectiveness increases with increasing ion valence.

  2. Puerperal endometritis and intrauterine adhesions.

    PubMed

    Polishuk, W Z; Anteby, S O; Weinstein, D

    1975-08-01

    The role of puerperal endometritis in intrauterine adhesion formation was studied by hysterography in 171 women who had cesarean sections. Of 28 patients who developed significant endometritis, only one developed intracervical adhesions. In the control group of 143 cases, there was also only one such case. Endometritis alone apparently does not play a significant role in intrauterine and endocervical adhesion formation. The possible role of placental fibroblasts in preventing endometrial regeneration is discussed. PMID:1158622

  3. Adhesion properties of gecko setae

    NASA Astrophysics Data System (ADS)

    Hill, Ginel; Peattie, Anne; Daniels, Roxanne; Full, Robert; Kenny, Thomas

    2005-03-01

    Millions of keratin hairs on gecko feet, called setae, act as a spectacular dry adhesive. Each seta branches into hundreds of smaller fibers that terminate in spatula-shaped ends. Morphological differences between the setae from different gecko species are suspected to affect both single-seta and whole-animal adhesion properties. Single-seta adhesive force measurements made using a MEMS piezoresistive cantilever capable of two-axis measurements are presented.

  4. Small Molecule Inhibitors Targeting Activator Protein 1 (AP-1)

    PubMed Central

    2015-01-01

    Activator protein 1 (AP-1) is a pivotal transcription factor that regulates a wide range of cellular processes including proliferation, apoptosis, differentiation, survival, cell migration, and transformation. Accumulating evidence supports that AP-1 plays an important role in several severe disorders including cancer, fibrosis, and organ injury, as well as inflammatory disorders such as asthma, psoriasis, and rheumatoid arthritis. AP-1 has emerged as an actively pursued drug discovery target over the past decade. Excitingly, a selective AP-1 inhibitor T-5224 (51) has been investigated in phase II human clinical trials. Nevertheless, no effective AP-1 inhibitors have yet been approved for clinical use. Despite significant advances achieved in understanding AP-1 biology and function, as well as the identification of small molecules modulating AP-1 associated signaling pathways, medicinal chemistry efforts remain an urgent need to yield selective and efficacious AP-1 inhibitors as a viable therapeutic strategy for human diseases. PMID:24831826

  5. Structural studies of human glioma pathogenesis-related protein 1

    SciTech Connect

    Asojo, Oluwatoyin A.; Koski, Raymond A.; Bonafé, Nathalie

    2011-10-01

    Structural analysis of a truncated soluble domain of human glioma pathogenesis-related protein 1, a membrane protein implicated in the proliferation of aggressive brain cancer, is presented. Human glioma pathogenesis-related protein 1 (GLIPR1) is a membrane protein that is highly upregulated in brain cancers but is barely detectable in normal brain tissue. GLIPR1 is composed of a signal peptide that directs its secretion, a conserved cysteine-rich CAP (cysteine-rich secretory proteins, antigen 5 and pathogenesis-related 1 proteins) domain and a transmembrane domain. GLIPR1 is currently being investigated as a candidate for prostate cancer gene therapy and for glioblastoma targeted therapy. Crystal structures of a truncated soluble domain of the human GLIPR1 protein (sGLIPR1) solved by molecular replacement using a truncated polyalanine search model of the CAP domain of stecrisp, a snake-venom cysteine-rich secretory protein (CRISP), are presented. The correct molecular-replacement solution could only be obtained by removing all loops from the search model. The native structure was refined to 1.85 Å resolution and that of a Zn{sup 2+} complex was refined to 2.2 Å resolution. The latter structure revealed that the putative binding cavity coordinates Zn{sup 2+} similarly to snake-venom CRISPs, which are involved in Zn{sup 2+}-dependent mechanisms of inflammatory modulation. Both sGLIPR1 structures have extensive flexible loop/turn regions and unique charge distributions that were not observed in any of the previously reported CAP protein structures. A model is also proposed for the structure of full-length membrane-bound GLIPR1.

  6. Topographically Tuning Polymer Adhesion

    NASA Astrophysics Data System (ADS)

    Crosby, Alfred

    2003-03-01

    Nature often uses geometry on micro and nano length scales to systematically tailor performance in multivariable environments. A great example, which has received much attention recently, is the foot of a gecko. The gecko's foot is covered with hundreds of thousands of "hair"-like protrusions which dictate a gecko's precise control of adhesion through van der Waals forces.(1) In our research, we fabricate controlled structures ranging from the nano to micro length scales on elastomeric surfaces. Our initial results are based on the topography of spherical caps and high-aspect ratio posts that decorate the surface of polydimethylsiloxane layers. Based on initial calculations, we demonstrate how the aspect ratio and inter-feature spacing greatly affects the near-surface compliance, thus impacting the processes of interface formation. The density and shape of the features are also shown to enhance the prevention of interfacial failure. These results are relevant for the refinement of the soft lithography processing technique, the development of smart adhesives, and the fabrication of bonding sites for biological implants. (1) Autumn, K.; Liang, Y.A.; Hsieh, S.T.; Zesch, W.; Chan, W.P.; Kenny,T.W.; Fearing, R.; Full, R.J. Nature 2000, 405, 681-685.

  7. Principles of adhesion.

    PubMed

    Baier, R E

    1992-01-01

    Understanding interfacial phenomena has been of direct relevance and practical benefit to extending the use of dental adhesives. Both surface physics, which describes properties of the inorganic materials' interfacial zones from their actual phase boundaries toward the bulk phases of the solids, and surface chemistry, which describes phenomena at the solid/biological interface and beyond it into the variable organic environment, have been important. High-energy materials include solids that are very hard, have high melting points, strong intermolecular forces, and basically crystalline structures, such as dental enamel. Low-energy materials, such as dentinal collagen, salivary films, and the organic resins of restorative materials, are softer, lower melting, and have weaker intermolecular forces, poorer crystallinity, and surface energies generally less than 100 ergs/cm. It has been a properly renewed emphasis on wetting of dental surfaces and their modification by primer coats, displacing or mixing with water and adsorbed proteinaceous films, that has promoted the success of many recently developed fourth-generation dentin adhesives. Their improved wettability for biological phases correlates directly with their better infiltration and anchoring of composites.

  8. Analysis and testing of adhesive bonds

    NASA Technical Reports Server (NTRS)

    Anderson, G. P.; Bennett, S. J.; Devries, K. L.

    1977-01-01

    An adhesive fracture mechanics approach is described with reference to the identification and design of the best tests for evaluating a given adhesive, the definition of the most meaningful fundamental parameters by which adhesives might be characterized, and the application of these parameters to the design of joints and to the prediction of their performance. Topics include standard adhesive test techniques, the theory of adhesive fracture, and adhesive fracture energy tests. Analytical methods and computer techniques for adhesive bonding, chemical and physical aspects of adhesive fracture, and specific applications and aspects of adhesive fracture mechanics are discussed.

  9. Stickiness--some fundamentals of adhesion.

    PubMed

    Gay, Cyprien

    2002-12-01

    We review some adhesion mechanisms that have been understood in the field of synthetic adhesives, and more precisely for adhesives that adhere instantaneously (a property named tackiness) and whose adhesive strength usually depends on the applied pressure (pressure-sensitive adhesives). The discussion includes effects of surface roughness, elasticity, cavitation, viscous and elastic fingering, substrate flexibility. PMID:21680396

  10. Stickiness--some fundamentals of adhesion.

    PubMed

    Gay, Cyprien

    2002-12-01

    We review some adhesion mechanisms that have been understood in the field of synthetic adhesives, and more precisely for adhesives that adhere instantaneously (a property named tackiness) and whose adhesive strength usually depends on the applied pressure (pressure-sensitive adhesives). The discussion includes effects of surface roughness, elasticity, cavitation, viscous and elastic fingering, substrate flexibility.

  11. Effect of adhesive thickness on adhesively bonded T-joint

    NASA Astrophysics Data System (ADS)

    Abdullah, A. R.; Afendi, Mohd; Majid, M. S. Abdul

    2013-12-01

    The aim of this work is to analyze the effect of adhesive thickness on tensile strength of adhesively bonded stainless steel T-joint. Specimens were made from SUS 304 Stainless Steel plate and SUS 304 Stainless Steel perforated plate. Four T-joint specimens with different adhesive thicknesses (0.5, 1.0, 1.5 and 2.0 mm) were made. Experiment result shows T-joint specimen with adhesive thickness of 1.0 mm yield highest maximum load. Identical T-joint specimen jointed by spot welding was also tested. Tensile test shows welded T-Joint had eight times higher tensile load than adhesively bonded T-joint. However, in low pressure application such as urea granulator chamber, high tensile strength is not mandatory. This work is useful for designer in fertilizer industry and others who are searching for alternative to spot welding.

  12. Improved Adhesion and Compliancy of Hierarchical Fibrillar Adhesives.

    PubMed

    Li, Yasong; Gates, Byron D; Menon, Carlo

    2015-08-01

    The gecko relies on van der Waals forces to cling onto surfaces with a variety of topography and composition. The hierarchical fibrillar structures on their climbing feet, ranging from mesoscale to nanoscale, are hypothesized to be key elements for the animal to conquer both smooth and rough surfaces. An epoxy-based artificial hierarchical fibrillar adhesive was prepared to study the influence of the hierarchical structures on the properties of a dry adhesive. The presented experiments highlight the advantages of a hierarchical structure despite a reduction of overall density and aspect ratio of nanofibrils. In contrast to an adhesive containing only nanometer-size fibrils, the hierarchical fibrillar adhesives exhibited a higher adhesion force and better compliancy when tested on an identical substrate.

  13. Stretchable, adhesion-tunable dry adhesive by surface wrinkling.

    PubMed

    Jeong, Hoon Eui; Kwak, Moon Kyu; Suh, Kahp Y

    2010-02-16

    We introduce a simple yet robust method of fabricating a stretchable, adhesion-tunable dry adhesive by combining replica molding and surface wrinkling. By utilizing a thin, wrinkled polydimethyl siloxane (PDMS) sheet with a thickness of 1 mm with built-in micropillars, active, dynamic control of normal and shear adhesion was achieved. Relatively strong normal (approximately 10.8 N/cm(2)) and shear adhesion (approximately 14.7 N/cm(2)) forces could be obtained for a fully extended (strained) PDMS sheet (prestrain of approximately 3%), whereas the forces could be rapidly reduced to nearly zero once the prestrain was released (prestrain of approximately 0.5%). Moreover, durability tests demonstrated that the adhesion strength in both the normal and shear directions was maintained over more than 100 cycles of attachment and detachment.

  14. Fire-Retardant Epoxy Adhesives

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Giants, T. W.

    1982-01-01

    Phosphorus-containing epoxy is fire-retardant and translucent. Intended as adhesive for laminated plastic sheets, new material bonds well to titanium dioxide-filled plastic film, which ordinarily shows little surface interaction with adhesives. Fire retardancy has been demonstrated, and smoke density is low enough to avoid smoke obscuration.

  15. Platelet adhesiveness in diabetes mellitus

    PubMed Central

    Shaw, S.; Pegrum, G. D.; Wolff, Sylvia; Ashton, W. L.

    1967-01-01

    Platelet adhesiveness has been assessed on whole blood from a series of 34 diabetics and 50 control subjects using adenosine diphosphate (A.D.P.) and by adherence to glass microspherules (ballotini). Using both techniques it was possible to demonstrate a significant increase in platelet adhesiveness in the diabetic patients. PMID:5614070

  16. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  17. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  18. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  19. 21 CFR 880.5240 - Medical adhesive tape and adhesive bandage.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Medical adhesive tape and adhesive bandage. 880... Personal Use Therapeutic Devices § 880.5240 Medical adhesive tape and adhesive bandage. (a) Identification. A medical adhesive tape or adhesive bandage is a device intended for medical purposes that...

  20. Epidural Lysis of Adhesions

    PubMed Central

    Lee, Frank; Jamison, David E.; Hurley, Robert W.

    2014-01-01

    As our population ages and the rate of spine surgery continues to rise, the use epidural lysis of adhesions (LOA) has emerged as a popular treatment to treat spinal stenosis and failed back surgery syndrome. There is moderate evidence that percutaneous LOA is more effective than conventional ESI for both failed back surgery syndrome, spinal stenosis, and lumbar radiculopathy. For cervical HNP, cervical stenosis and mechanical pain not associated with nerve root involvement, the evidence is anecdotal. The benefits of LOA stem from a combination of factors to include the high volumes administered and the use of hypertonic saline. Hyaluronidase has been shown in most, but not all studies to improve treatment outcomes. Although infrequent, complications are more likely to occur after epidural LOA than after conventional epidural steroid injections. PMID:24478895

  1. Adhesion testing device

    NASA Technical Reports Server (NTRS)

    LaPeyronnie, Glenn M. (Inventor); Huff, Charles M. (Inventor)

    2010-01-01

    The present invention provides a testing apparatus and method for testing the adhesion of a coating to a surface. The invention also includes an improved testing button or dolly for use with the testing apparatus and a self aligning button hook or dolly interface on the testing apparatus. According to preferred forms, the apparatus and method of the present invention are simple, portable, battery operated rugged, and inexpensive to manufacture and use, are readily adaptable to a wide variety of uses, and provide effective and accurate testing results. The device includes a linear actuator driven by an electric motor coupled to the actuator through a gearbox and a rotatable shaft. The electronics for the device are contained in the head section of the device. At the contact end of the device, is positioned a self aligning button hook, attached below the load cell located on the actuator shaft.

  2. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, R.A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe with an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough. 4 figs.

  3. Biological adhesives and fastening devices

    NASA Astrophysics Data System (ADS)

    Wolpert, H. D.

    2012-04-01

    Sea creatures are a leading source to some of the more interesting discoveries in adhesives. Because sea water naturally breaks down even the strongest conventional adhesive, an alternative is important that could be used in repairing or fabricating anything that might have regular contact with moisture such as: Repairing broken and shattered bones, developing a surgical adhesive, use in the dental work, repairing and building ships, and manufacturing plywood. Some of nature's prototypes include the common mussel, limpet, some bacteria and abalone. As we learn more about these adhesives we are also developing non adhesive fasteners, such as mimicked after studying the octopus, burdock burrs (i.e. Velcro®) and the gecko.

  4. Corrugated pipe adhesive applicator apparatus

    DOEpatents

    Shirey, Ray A.

    1983-06-14

    Apparatus for coating selected portions of the troughs of a corrugated pipe within an adhesive includes a support disposed within the pipe with a reservoir containing the adhesive disposed on the support. A pump, including a spout, is utilized for supplying the adhesive from the reservoir to a trough of the pipe. A rotatable applicator is supported on the support and contacts the trough of the pipe. The applicator itself is sized so as to fit within the trough, and contacts the adhesive in the trough and spreads the adhesive in the trough upon rotation. A trough shield, supported by the support and disposed in the path of rotation of the applicator, is utilized to prevent the applicator from contacting selected portions of the trough. A locator head is also disposed on the support and provides a way for aligning the spout, the applicator, and the trough shield with the trough.

  5. Neutrophil adhesion in leukocyte adhesion deficiency syndrome type 2.

    PubMed Central

    Phillips, M L; Schwartz, B R; Etzioni, A; Bayer, R; Ochs, H D; Paulson, J C; Harlan, J M

    1995-01-01

    We have previously reported a newly discovered congenital disorder of neutrophil adhesion, leukocyte adhesion deficiency syndrome type 2 (LAD II). The clinical manifestations of this syndrome are similar to those seen in the classic leukocyte adhesion deficiency syndrome, now designated type 1 (LAD I), but the two syndromes differ in the molecular basis of their adhesion defects. LAD I is caused by a deficiency in the CD18 integrin adhesion molecules while LAD II patients are deficient in expression of sialyl-Lewis X (SLeX), a carbohydrate ligand for selectins. In this report we demonstrate that neutrophils from a LAD II patient bind minimally or not at all to recombinant E-selectin, purified platelet P-selectin, or P-selectin expressed on histamine-activated human umbilical vein endothelial cells, but have normal levels of L-selectin and CD11b/CD18 integrin, and adhere to and migrate across endothelium when CD11b/CD18 is activated. We compare LAD I and LAD II patient neutrophil function in vitro, demonstrating that integrin and selectin adhesion molecules have distinct but interdependent roles in neutrophil adhesion during an inflammatory response. Images PMID:8675661

  6. Revisiting Apoplastic Auxin Signaling Mediated by AUXIN BINDING PROTEIN 1

    PubMed Central

    Feng, Mingxiao; Kim, Jae-Yean

    2015-01-01

    It has been suggested that AUXIN BINDING PROTEIN 1 (ABP1) functions as an apoplastic auxin receptor, and is known to be involved in the post-transcriptional process, and largely independent of the already well-known SKP-cullin-F-box-transport inhibitor response (TIR1) /auxin signaling F-box (AFB) (SCFTIR1/AFB) pathway. In the past 10 years, several key components downstream of ABP1 have been reported. After perceiving the auxin signal, ABP1 interacts, directly or indirectly, with plasma membrane (PM)-localized transmembrane proteins, transmembrane kinase (TMK) or SPIKE1 (SPK1), or other unidentified proteins, which transfer the signal into the cell to the Rho of plants (ROP). ROPs interact with their effectors, such as the ROP interactive CRIB motif-containing protein (RIC), to regulate the endocytosis/exocytosis of the auxin efflux carrier PIN-FORMED (PIN) proteins to mediate polar auxin transport across the PM. Additionally, ABP1 is a negative regulator of the traditional SCFTIR1/AFB auxin signaling pathway. However, Gao et al. (2015) very recently reported that ABP1 is not a key component in auxin signaling, and the famous abp1-1 and abp1-5 mutant Arabidopsis lines are being called into question because of possible additional mutantion sites, making it necessary to reevaluate ABP1. In this review, we will provide a brief overview of the history of ABP1 research. PMID:26467289

  7. Iron Regulatory Protein-1 Protects against Mitoferrin-1-deficient Porphyria*

    PubMed Central

    Chung, Jacky; Anderson, Sheila A.; Gwynn, Babette; Deck, Kathryn M.; Chen, Michael J.; Langer, Nathaniel B.; Shaw, George C.; Huston, Nicholas C.; Boyer, Leah F.; Datta, Sumon; Paradkar, Prasad N.; Li, Liangtao; Wei, Zong; Lambert, Amy J.; Sahr, Kenneth; Wittig, Johannes G.; Chen, Wen; Lu, Wange; Galy, Bruno; Schlaeger, Thorsten M.; Hentze, Matthias W.; Ward, Diane M.; Kaplan, Jerry; Eisenstein, Richard S.; Peters, Luanne L.; Paw, Barry H.

    2014-01-01

    Mitochondrial iron is essential for the biosynthesis of heme and iron-sulfur ([Fe-S]) clusters in mammalian cells. In developing erythrocytes, iron is imported into the mitochondria by MFRN1 (mitoferrin-1, SLC25A37). Although loss of MFRN1 in zebrafish and mice leads to profound anemia, mutant animals showed no overt signs of porphyria, suggesting that mitochondrial iron deficiency does not result in an accumulation of protoporphyrins. Here, we developed a gene trap model to provide in vitro and in vivo evidence that iron regulatory protein-1 (IRP1) inhibits protoporphyrin accumulation. Mfrn1+/gt;Irp1−/− erythroid cells exhibit a significant increase in protoporphyrin levels. IRP1 attenuates protoporphyrin biosynthesis by binding to the 5′-iron response element (IRE) of alas2 mRNA, inhibiting its translation. Ectopic expression of alas2 harboring a mutant IRE, preventing IRP1 binding, in Mfrn1gt/gt cells mimics Irp1 deficiency. Together, our data support a model whereby impaired mitochondrial [Fe-S] cluster biogenesis in Mfrn1gt/gt cells results in elevated IRP1 RNA-binding that attenuates ALAS2 mRNA translation and protoporphyrin accumulation. PMID:24509859

  8. Iron regulatory protein-1 protects against mitoferrin-1-deficient porphyria.

    PubMed

    Chung, Jacky; Anderson, Sheila A; Gwynn, Babette; Deck, Kathryn M; Chen, Michael J; Langer, Nathaniel B; Shaw, George C; Huston, Nicholas C; Boyer, Leah F; Datta, Sumon; Paradkar, Prasad N; Li, Liangtao; Wei, Zong; Lambert, Amy J; Sahr, Kenneth; Wittig, Johannes G; Chen, Wen; Lu, Wange; Galy, Bruno; Schlaeger, Thorsten M; Hentze, Matthias W; Ward, Diane M; Kaplan, Jerry; Eisenstein, Richard S; Peters, Luanne L; Paw, Barry H

    2014-03-14

    Mitochondrial iron is essential for the biosynthesis of heme and iron-sulfur ([Fe-S]) clusters in mammalian cells. In developing erythrocytes, iron is imported into the mitochondria by MFRN1 (mitoferrin-1, SLC25A37). Although loss of MFRN1 in zebrafish and mice leads to profound anemia, mutant animals showed no overt signs of porphyria, suggesting that mitochondrial iron deficiency does not result in an accumulation of protoporphyrins. Here, we developed a gene trap model to provide in vitro and in vivo evidence that iron regulatory protein-1 (IRP1) inhibits protoporphyrin accumulation. Mfrn1(+/gt);Irp1(-/-) erythroid cells exhibit a significant increase in protoporphyrin levels. IRP1 attenuates protoporphyrin biosynthesis by binding to the 5'-iron response element (IRE) of alas2 mRNA, inhibiting its translation. Ectopic expression of alas2 harboring a mutant IRE, preventing IRP1 binding, in Mfrn1(gt/gt) cells mimics Irp1 deficiency. Together, our data support a model whereby impaired mitochondrial [Fe-S] cluster biogenesis in Mfrn1(gt/gt) cells results in elevated IRP1 RNA-binding that attenuates ALAS2 mRNA translation and protoporphyrin accumulation.

  9. Revisiting Apoplastic Auxin Signaling Mediated by AUXIN BINDING PROTEIN 1.

    PubMed

    Feng, Mingxiao; Kim, Jae-Yean

    2015-10-01

    It has been suggested that AUXIN BINDING PROTEIN 1 (ABP1) functions as an apoplastic auxin receptor, and is known to be involved in the post-transcriptional process, and largely independent of the already well-known SKP-cullin-F-box-transport inhibitor response (TIR1) /auxin signaling F-box (AFB) (SCF(TIR1/AFB)) pathway. In the past 10 years, several key components downstream of ABP1 have been reported. After perceiving the auxin signal, ABP1 interacts, directly or indirectly, with plasma membrane (PM)-localized transmembrane proteins, transmembrane kinase (TMK) or SPIKE1 (SPK1), or other unidentified proteins, which transfer the signal into the cell to the Rho of plants (ROP). ROPs interact with their effectors, such as the ROP interactive CRIB motif-containing protein (RIC), to regulate the endocytosis/exocytosis of the auxin efflux carrier PIN-FORMED (PIN) proteins to mediate polar auxin transport across the PM. Additionally, ABP1 is a negative regulator of the traditional SCF(TIR1/AFB) auxin signaling pathway. However, Gao et al. (2015) very recently reported that ABP1 is not a key component in auxin signaling, and the famous abp1-1 and abp1-5 mutant Arabidopsis lines are being called into question because of possible additional mutantion sites, making it necessary to reevaluate ABP1. In this review, we will provide a brief overview of the history of ABP1 research.

  10. Immunohistochemical localization of dentin matrix protein 1 in human dentin.

    PubMed

    Orsini, G; Ruggeri, A; Mazzoni, A; Nato, F; Falconi, M; Putignano, A; Di Lenarda, R; Nanci, A; Breschi, L

    2008-01-01

    Dentin matrix protein 1 (DMP1) is a non-collagenous matrix protein with a recognized role in the formation of mineralized tissues such as dentin. The aim of this study was to analyze the distribution of DMP1 in human dentin by means of immunofluorescence and high-resolution immunogold labeling. Fully developed, sound human dentin specimens were submitted to fluorescence labeling and post-embedding immunolabeling techniques with a rabbit polyclonal antihuman DMP1 antibody followed by corresponding fluorochrome-conjugated or gold-conjugated secondary antibodies. Both immunofluorescence and immunogold labeling showed an intense labeling associated with the peritubular dentin. In addition, at the ultrastructural level, there was also a moderate and diffuse immunoreaction over intertubular dentin, and a weak labeling within predentin which increased in density towards the mineralization front. This study suggests that in adult human teeth, like in rodents, DMP1 is prevalently concentrated at the level of peritubular dentin and this feature is preserved also in fully developed-teeth. These data are consistent with what has been observed in rodents and suggest that DMP1 plays a role in maintenance of the dentin tubular space.

  11. Glycosylation of Dentin Matrix Protein 1 is critical for osteogenesis

    PubMed Central

    Sun, Yao; Weng, Yuteng; Zhang, Chenyang; Liu, Yi; Kang, Chen; Liu, Zhongshuang; Jing, Bo; Zhang, Qi; Wang, Zuolin

    2015-01-01

    Proteoglycans play important roles in regulating osteogenesis. Dentin matrix protein 1 (DMP1) is a highly expressed bone extracellular matrix protein that regulates both bone development and phosphate metabolism. After glycosylation, an N-terminal fragment of DMP1 protein was identified as a new proteoglycan (DMP1-PG) in bone matrix. In vitro investigations showed that Ser89 is the key glycosylation site in mouse DMP1. However, the specific role of DMP1 glycosylation is still not understood. In this study, a mutant DMP1 mouse model was developed in which the glycosylation site S89 was substituted with G89 (S89G-DMP1). The glycosylation level of DMP1 was down-regulated in the bone matrix of S89G-DMP1 mice. Compared with wild type mice, the long bones of S89G-DMP1 mice showed developmental changes, including the speed of bone remodeling and mineralization, the morphology and activities of osteocytes, and activities of both osteoblasts and osteoclasts. These findings indicate that glycosylation of DMP1 is a key posttranslational modification process during development and that DMP1-PG functions as an indispensable proteoglycan in osteogenesis. PMID:26634432

  12. Glycosylation of Dentin Matrix Protein 1 is critical for osteogenesis.

    PubMed

    Sun, Yao; Weng, Yuteng; Zhang, Chenyang; Liu, Yi; Kang, Chen; Liu, Zhongshuang; Jing, Bo; Zhang, Qi; Wang, Zuolin

    2015-12-04

    Proteoglycans play important roles in regulating osteogenesis. Dentin matrix protein 1 (DMP1) is a highly expressed bone extracellular matrix protein that regulates both bone development and phosphate metabolism. After glycosylation, an N-terminal fragment of DMP1 protein was identified as a new proteoglycan (DMP1-PG) in bone matrix. In vitro investigations showed that Ser(89) is the key glycosylation site in mouse DMP1. However, the specific role of DMP1 glycosylation is still not understood. In this study, a mutant DMP1 mouse model was developed in which the glycosylation site S(89) was substituted with G(89) (S89G-DMP1). The glycosylation level of DMP1 was down-regulated in the bone matrix of S89G-DMP1 mice. Compared with wild type mice, the long bones of S89G-DMP1 mice showed developmental changes, including the speed of bone remodeling and mineralization, the morphology and activities of osteocytes, and activities of both osteoblasts and osteoclasts. These findings indicate that glycosylation of DMP1 is a key posttranslational modification process during development and that DMP1-PG functions as an indispensable proteoglycan in osteogenesis.

  13. The Bone Morphogenetic Protein 1/Tolloid-like Metalloproteinases

    PubMed Central

    Hopkins, Delana R.; Keles, Sunduz; Greenspan, Daniel S.

    2009-01-01

    A decade ago, bone morphogenetic protein 1 (BMP1) was shown to provide the activity necessary for proteolytic removal of the C-propeptides of procollagens I–III: precursors of the major fibrillar collagens. Subsequent studies have shown BMP1 to be the prototype of a small group of extracellular metalloproteinases that play manifold roles in regulating formation of the extracellular matrix (ECM). Soon after initial cloning of BMP1, genetic studies showed the related Drosophila proteinase Tolloid (TLD) to be necessary for formation of the dorsal-ventral axis in early embryogenesis. It is now clear that the BMP1/TLD-like proteinases, conserved in species ranging from Drosophila to humans, act in dorsal-ventral patterning via activation of transforming growth factor β (TGFβ)-like proteins BMP2, BMP4 (vertebrates) and decapentaplegic (arthropods). More recently, it has become apparent that the BMP1/TLD-like proteinases are key activators of a broader subset of the TGFβ superfamily of proteins, with implications that these proteinases may be key in orchestrating formation of ECM with growth factor activation and BMP signaling in morphogenetic processes. PMID:17560775

  14. Differential regulation of dentin matrix protein 1 expression during odontogenesis.

    PubMed

    Lu, Yongbo; Zhang, Shubin; Xie, Yixia; Pi, Yuli; Feng, Jian Q

    2005-01-01

    Dentin matrix protein 1 (DMP1) is highly expressed in mineralized tooth and bone. Both in vitro and in vivo data show that DMP1 is critical for mineralization and tooth morphogenesis (growth and development). In this study, we studied Dmp1 gene regulation. The in vitro transient transfection assay identified two important DNA fragments, the 2.4- and 9.6-kb promoter regions. We next generated and analyzed transgenic mice bearing the beta-galactosidase (lacZ) reporter gene driven by the 2.4- or 9.6-kb promoter with the complete 4-kb intron 1. The 9.6-kb Dmp1-lacZ mice conferred a DMP1 expression pattern in odontoblasts identical to that in the endogenous Dmp1 gene. This is reflected by lacZ expression in Dmp1-lacZ knock-in mice during all stages of odontogenesis. In contrast, the 2.4-kb Dmp1-lacZ mice display activity in odontoblast cells only at the early stage of odontogenesis. Thus, we propose that different transcription factors regulate early or later cis-regulatory domains of the Dmp1 promoter, which gives rise to the unique spatial and temporal expression pattern of Dmp1 gene at different stages of tooth development.

  15. Cloning and expression of recombinant adhesive protein Mefp-1 of the blue mussel, Mytilus edulis

    DOEpatents

    Silverman, Heather G.; Roberto, Francisco F.

    2006-01-17

    The present invention comprises a Mytilus edulis cDNA sequenc having a nucleotide sequence that encodes for the Mytilus edulis foot protein-1 (Mefp-1), an example of a mollusk foot protein. Mefp-1 is an integral component of the blue mussels' adhesive protein complex, which allows the mussel to attach to objects underwater. The isolation, purification and sequencing of the Mefp-1 gene will allow researchers to produce Mefp-1 protein using genetic engineering techniques. The discovery of Mefp-1 gene sequence will also allow scientists to better understand how the blue mussel creates its waterproof adhesive protein complex.

  16. Enhanced adhesion by gecko-inspired hierarchical fibrillar adhesives.

    PubMed

    Murphy, Michael P; Kim, Seok; Sitti, Metin

    2009-04-01

    The complex structures that allow geckos to repeatably adhere to surfaces consist of multilevel branching fibers with specialized tips. We present a novel technique for fabricating similar multilevel structures from polymer materials and demonstrate the fabrication of arrays of two- and three-level structures, wherein each level terminates in flat mushroom-type tips. Adhesion experiments are conducted on two-level fiber arrays on a 12-mm-diameter glass hemisphere, which exhibit both increased adhesion and interface toughness over one-level fiber samples and unstructured control samples. These adhesion enhancements are the result of increased surface conformation as well as increased extension during detachment.

  17. Wet Adhesion and Adhesive Locomotion of Snails on Anti-Adhesive Non-Wetting Surfaces

    PubMed Central

    Shirtcliffe, Neil J.; McHale, Glen; Newton, Michael I.

    2012-01-01

    Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted), texture (smooth, rough or granular) or wetting property (hydrophilic or hydrophobic) via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces. PMID:22693563

  18. Marine Bioinspired Underwater Contact Adhesion.

    PubMed

    Clancy, Sean K; Sodano, Antonio; Cunningham, Dylan J; Huang, Sharon S; Zalicki, Piotr J; Shin, Seunghan; Ahn, B Kollbe

    2016-05-01

    Marine mussels and barnacles are sessile biofouling organisms that adhere to a number of surfaces in wet environments and maintain remarkably strong bonds. Previous synthetic approaches to mimic biological wet adhesive properties have focused mainly on the catechol moiety, present in mussel foot proteins (mfps), and especially rich in the interfacial mfps, for example, mfp-3 and -5, found at the interface between the mussel plaque and substrate. Barnacles, however, do not use Dopa for their wet adhesion, but are instead rich in noncatecholic aromatic residues. Due to this anomaly, we were intrigued to study the initial contact adhesion properties of copolymerized acrylate films containing the key functionalities of barnacle cement proteins and interfacial mfps, for example, aromatic (catecholic or noncatecholic), cationic, anionic, and nonpolar residues. The initial wet contact adhesion of the copolymers was measured using a probe tack testing apparatus with a flat-punch contact geometry. The wet contact adhesion of an optimized, bioinspired copolymer film was ∼15.0 N/cm(2) in deionized water and ∼9.0 N/cm(2) in artificial seawater, up to 150 times greater than commercial pressure-sensitive adhesive (PSA) tapes (∼0.1 N/cm(2)). Furthermore, maximum wet contact adhesion was obtained at ∼pH 7, suggesting viability for biomedical applications. PMID:27046671

  19. Osteoblast adhesion on nanophase ceramics.

    PubMed

    Webster, T J; Siegel, R W; Bizios, R

    1999-07-01

    Osteoblast adhesion on nanophase alumina (Al2O3) and titania (TiO2) was investigated in vitro. Osteoblast adhesion to nanophase alumina and titania in the absence of serum from Dulbecco's modified Eagle medium (DMEM) was significantly (P < 0.01) less than osteoblast adhesion to alumina and titania in the presence of serum. In the presence of 10% fetal bovine serum in DMEM osteoblast adhesion on nanophase alumina (23 nm grain size) and titania (32 nm grain size) was significantly (P < 0.05) greater than on conventional alumina (177 nm grain size) and titania (2.12 microm grain size), respectively, after 1, 2, and 4 h. Further investigation of the dependence of osteoblast adhesion on alumina and titania grain size indicated the presence of a critical grain size for osteoblast adhesion between 49 and 67 nm for alumina and 32 and 56 nm for titania. The present study provides evidence of the ability of nanophase alumina and titania to simulate material characteristics (such as surface grain size) of physiological bone that enhance protein interactions (such as adsorption, configuration, bioactivity, etc.) and subsequent osteoblast adhesion.

  20. Identification and characterization of merozoite surface protein 1 epitope

    PubMed Central

    Singh, Satarudra Prakash; Mishra, Bhartendu Nath

    2009-01-01

    Malaria is an important tropical infection which urgently requires intervention of an effective vaccine. Antigenic variations of the parasite and allelic diversity of the host are main problems in the development of an effective malaria vaccine. Cytotoxic T lymphocytes (CTL) directed against Plasmodium falciparum­derived antigens are shown to play an important role for the protection against malaria. The merozoite surface protein 1 (MSP1) is expressed in all the four life-cycle stages of Plasmodium falciparum and did not find any sequence similarity to human and mouse reference proteins. MSP1 is a known target of the immune response and a single CTL epitope binding to the HLA­A*0201 is available for merozoite form. Here, we report the results from the computational characterization of MSP1, precursor (1720 residue) and screening of highest scoring potential CTL epitopes for 1712 overlapping peptides binding to thirty four HLA class­I alleles and twelve HLA class­I supertypes (5 HLA­A and 7 HLA­B) using bioinformatics tools. Supertypes are the clustered groups of HLA class­I molecules, representing a sets of molecules that share largely overlapping peptide binding specificity. The prediction results for MSP1 as adhesin and adhesin-like in terms of probability is 1.0. Results also show that MSP1 has orthologs to other related species as well as having non allergenicity and single transmembrane properties demonstrating its suitability as a vaccine candidate. The predicted peptides are expected to be useful in the design of multi-epitope vaccines without compromising the human population coverage. PMID:20011145

  1. Adhesives from modified soy protein

    DOEpatents

    Sun, Susan; Wang, Donghai; Zhong, Zhikai; Yang, Guang

    2008-08-26

    The, present invention provides useful adhesive compositions having similar adhesive properties to conventional UF and PPF resins. The compositions generally include a protein portion and modifying ingredient portion selected from the group consisting of carboxyl-containing compounds, aldehyde-containing compounds, epoxy group-containing compounds, and mixtures thereof. The composition is preferably prepared at a pH level at or near the isoelectric point of the protein. In other preferred forms, the adhesive composition includes a protein portion and a carboxyl-containing group portion.

  2. Foreign material in postoperative adhesions.

    PubMed Central

    Luijendijk, R W; de Lange, D C; Wauters, C C; Hop, W C; Duron, J J; Pailler, J L; Camprodon, B R; Holmdahl, L; van Geldorp, H J; Jeekel, J

    1996-01-01

    OBJECTIVE: The authors determined the prevalence of foreign body granulomas in intra-abdominal adhesions in patients with a history of abdominal surgery. PATIENTS AND METHODS: In a cross-sectional, multicenter, multinational study, adult patients with a history of one or more previous abdominal operations and scheduled for laparotomy between 1991 and 1993 were examined during surgery. Patients in whom adhesions were present were selected for study. Quantity, distribution, and quality of adhesions were scored, and adhesion samples were taken for histologic examination. RESULTS: In 448 studied patients, the adhesions were most frequently attached to the omentum (68%) and the small bowel (67%). The amount of adhesions was significantly smaller in patients with a history of only one minor operation or one major operation, compared with those with multiple laparotomies (p < 0.001). Significantly more adhesions were found in patients with a history of adhesions at previous laparotomy (p < 0.001), with presence of abdominal abscess, hematoma, and intestinal leakage as complications after former surgery (p = 0.01, p = 0.002, and p < 0.001, respectively), and with a history of an unoperated inflammatory process (p = 0.04). Granulomas were found in 26% of all patients. Suture granulomas were found in 25% of the patients. Starch granulomas were present in 5% of the operated patients whose surgeons wore starch-containing gloves. When suture granulomas were present, the median interval between the present and the most recent previous laparotomy was 13 months. When suture granulomas were absent, this interval was significantly longer--i.e., 30 months (p = 0.002). The percentage of patients with suture granulomas decreased gradually from 37% if the previous laparotomy had occurred up to 6 months before the present operation, to 18% if the previous laparotomy had occurred more than 2 years ago (p < 0.001). CONCLUSIONS: The number of adhesions found at laparotomy was significantly

  3. Interfacial adhesion of carbon fibers

    NASA Technical Reports Server (NTRS)

    Bascom, Willard D.

    1987-01-01

    Relative adhesion strengths between AS4, AS1, and XAS carbon fibers and thermoplastic polymers were determined using the embedded single filament test. Polymers studied included polycarbonate, polyphenylene oxide, polyetherimide, polysulfone, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate polysiloxane block copolymer. Fiber surface treatments and sizings improved adhesion somewhat, but adhesion remained well below levels obtained with epoxy matrices. An explanation for the differences between the Hercules and Grafil fibers was sought using X ray photon spectroscopy, wetting, scanning electron microscopy and thermal desorption analysis.

  4. Notch-Mediated Cell Adhesion

    PubMed Central

    Murata, Akihiko; Hayashi, Shin-Ichi

    2016-01-01

    Notch family members are generally recognized as signaling molecules that control various cellular responses in metazoan organisms. Early fly studies and our mammalian studies demonstrated that Notch family members are also cell adhesion molecules; however, information on the physiological roles of this function and its origin is limited. In this review, we discuss the potential present and ancestral roles of Notch-mediated cell adhesion in order to explore its origin and the initial roles of Notch family members dating back to metazoan evolution. We hypothesize that Notch family members may have initially emerged as cell adhesion molecules in order to mediate multicellularity in the last common ancestor of metazoan organisms. PMID:26784245

  5. Photovoltaic module with adhesion promoter

    DOEpatents

    Xavier, Grace

    2013-10-08

    Photovoltaic modules with adhesion promoters and methods for fabricating photovoltaic modules with adhesion promoters are described. A photovoltaic module includes a solar cell including a first surface and a second surface, the second surface including a plurality of interspaced back-side contacts. A first glass layer is coupled to the first surface by a first encapsulating layer. A second glass layer is coupled to the second surface by a second encapsulating layer. At least a portion of the second encapsulating layer is bonded directly to the plurality of interspaced back-side contacts by an adhesion promoter.

  6. Advances in light curing adhesives

    NASA Astrophysics Data System (ADS)

    Bachmann, Andy

    2001-11-01

    This paper describes the development of a new family of light curing adhesives containing a new reactive additive previously not used in optical grade light curing adhesives are obtained with the addition of functionalized cellulositics. Outgassing as low as 10-6 grams/gram has been observed based on headspace sampling. Other additives have lowered the shrinkage rates of positioning adhesives from near 1 percent to less than 0.1 percent with fractional, percentage movements over thermal range of -40 degrees C to +200 degrees C.

  7. Wear mechanism based on adhesion

    NASA Technical Reports Server (NTRS)

    Yamamoto, T.; Buckley, D. H.

    1982-01-01

    Various concepts concerning wear mechanisms and deformation behavior observed in the sliding wear track are surveyed. The mechanisms for wear fragment formation is discussed on the basis of adhesion. The wear process under unlubricated sliding conditions is explained in relation to the concept of adhesion at the interface during the sliding process. The mechanism for tearing away the surface layer from the contact area and forming the sliding track contour is explained by assuming the simplified process of material removal based on the adhesion theory.

  8. Reversing Adhesion: A Triggered Release Self‐Reporting Adhesive

    PubMed Central

    Schenzel, Alexander M.; Klein, Christopher; Rist, Kai; Moszner, Norbert

    2016-01-01

    Here, the development of an adhesive is reported – generated via free radical polymerization – which can be degraded upon thermal impact within minutes. The degradation is based on a stimuli responsive moiety (SRM) that is incorporated into the network. The selected SRM is a hetero Diels‐Alder (HDA) moiety that features three key properties. First, the adhesive can be degraded at relatively low temperatures (≈80 °C), second the degradation occurs very rapidly (less than 3 min), and third, the degradation of the network can readily be analyzed and quantified due to its self‐reporting nature. The new reversible self‐reporting adhesion system is characterized in detail starting from molecular studies of the retro HDA reaction. Moreover, the mechanical properties of the network, as well as the adhesion forces, are investigated in detail and compared to common methacrylate‐based systems, demonstrating a significant decrease in mechanic stability at elevated temperatures. The current study thus represents a significant advance of the current state of the art for debonding on demand adhesives, making the system interesting for several fields of application including dental adhesives. PMID:27812461

  9. Adhesion in vascular biology

    PubMed Central

    de Rooij, Johan

    2014-01-01

    The vasculature delivers vital support for all other tissues by supplying oxygen and nutrients for growth and by transporting the immune cells that protect and cure them. Therefore, the microvasculature developed a special barrier that is permissive for gasses like oxygen and carbon dioxide, while fluids are kept inside and pathogens are kept out. While maintaining this tight barrier, the vascular wall also allows immune cells to exit at sites of inflammation or damage, a process that is called transmigration. The endothelial cell layer that forms the inner lining of the vasculature is crucial for the vascular barrier function as well as the regulation of transmigration. Therefore, adhesions between vascular endothelial cells are both tight and dynamic and the mechanisms by which they are established, and the mechanisms by which they are controlled have been extensively studied over the past decades. Because of our fundamental strive to understand biology, but also because defects in vascular barrier control cause a variety of clinical problems and treatment strategies may evolve from our detailed understanding of its mechanisms. This special focus issue features a collection of articles that review key components of the development and control of the endothelial cell-cell junction that is central to endothelial barrier function. PMID:25422845

  10. Seafood delicacy makes great adhesive

    ScienceCinema

    Idaho National Laboratory - Frank Roberto, Heather Silverman

    2016-07-12

    Technology from Mother Nature is often hard to beat, so Idaho National Laboratory scientistsgenetically analyzed the adhesive proteins produced by blue mussels, a seafood delicacy. Afterobtaining full-length DNA sequences encoding these proteins, reprod

  11. Seafood delicacy makes great adhesive

    SciTech Connect

    Idaho National Laboratory - Frank Roberto, Heather Silverman

    2008-03-26

    Technology from Mother Nature is often hard to beat, so Idaho National Laboratory scientistsgenetically analyzed the adhesive proteins produced by blue mussels, a seafood delicacy. Afterobtaining full-length DNA sequences encoding these proteins, reprod

  12. Adhesive interactions between vesicles in the strong adhesion limit

    PubMed Central

    Ramachandran, Arun; Anderson, Travers H.; Leal, L. Gary; Israelachvili, Jacob N.

    2010-01-01

    We consider the adhesive interaction energy between a pair of vesicles in the strong adhesion limit, in which bending forces play a negligible role in determining vesicle shape compared to forces due to membrane stretching. Although force-distance or energy distance relationships characterizing adhesive interactions between fluid bilayers are routinely measured using the surface forces apparatus, the atomic force microscope and the biomembrane force probe, the interacting bilayers in these methods are supported on surfaces (e.g. mica sheet) and cannot be deformed. However, it is known that in a suspension, vesicles composed of the same bilayer can deform by stretching or bending, and can also undergo changes in volume. Adhesively interacting vesicles can thus form flat regions in the contact zone, which will result in an enhanced interaction energy as compared to rigid vesicles. The focus of this paper is to examine the magnitude of the interaction energy between adhesively interacting, deformed vesicles relative to free, undeformed vesicles as a function of the intervesicle separation. The modification of the intervesicle interaction energy due to vesicle deformability can be calculated knowing the undeformed radius of the vesicles, R0, the bending modulus kb, the area expansion modulus Ka, and the adhesive minimum WP(0) and separation DP(0) in the energy of interaction between two flat bilayers, which can be obtained from the force-distance measurements made using the above supported-bilayer methods. For vesicles with constant volumes, we show that adhesive potentials between non-deforming bilayers such as ∣WP(0)∣∼5×10−4mJ/m2, which are ordinarily considered weak in colloidal physics literature, can result in significantly deep (>10×) energy minima due to increase in vesicle area and flattening in the contact region. If the osmotic expulsion of water across the vesicles driven by the tense, stretched membrane in the presence of an osmotically active

  13. Adhesive interactions between vesicles in the strong adhesion limit.

    PubMed

    Ramachandran, Arun; Anderson, Travers H; Leal, L Gary; Israelachvili, Jacob N

    2011-01-01

    We consider the adhesive interaction energy between a pair of vesicles in the strong adhesion limit, in which bending forces play a negligible role in determining vesicle shape compared to forces due to membrane stretching. Although force−distance or energy−distance relationships characterizing adhesive interactions between fluid bilayers are routinely measured using the surface forces apparatus, the atomic force microscope, and the biomembrane force probe, the interacting bilayers in these methods are supported on surfaces (e.g., mica sheet) and cannot be deformed. However, it is known that, in a suspension, vesicles composed of the same bilayer can deform by stretching or bending, and can also undergo changes in volume. Adhesively interacting vesicles can thus form flat regions in the contact zone, which will result in an enhanced interaction energy as compared to rigid vesicles. The focus of this paper is to examine the magnitude of the interaction energy between adhesively interacting, deformed vesicles relative to free, undeformed vesicles as a function of the intervesicle separation. The modification of the intervesicle interaction energy due to vesicle deformability can be calculated knowing the undeformed radius of the vesicles, R0, the bending modulus, k(b), the area expansion modulus, k(a), and the adhesive minimum, W(P)(0), and separation, D(P)(0), in the energy of interaction between two flat bilayers, which can be obtained from the force−distance measurements made using the above supported-bilayer methods. For vesicles with constant volumes, we show that adhesive potentials between nondeforming bilayers such as |W(P)(0)| 5 × 10(−4) mJ/m2, which are ordinarily considered weak in the colloidal physics literature, can result in significantly deep (>10×) energy minima due to increase in vesicle area and flattening in the contact region. If the osmotic expulsion of water across the vesicles driven by the tense, stretched membrane in the presence

  14. Mechanisms of adhesion in geckos.

    PubMed

    Autumn, Kellar; Peattie, Anne M

    2002-12-01

    The extraordinary adhesive capabilities of geckos have challenged explanation for millennia, since Aristotle first recorded his observations. We have discovered many of the secrets of gecko adhesion, yet the millions of dry, adhesive setae on the toes of geckos continue to generate puzzling new questions and valuable answers. Each epidermally-derived, keratinous seta ends in hundreds of 200 nm spatular tips, permitting intimate contact with rough and smooth surfaces alike. Prior studies suggested that adhesive force in gecko setae was directly proportional to the water droplet contact angle (θ) , an indicator of the free surface energy of a substrate. In contrast, new theory suggests that adhesion energy between a gecko seta and a surface (W(GS)) is in fact proportional to (1 + cosθ), and only for θ > 60°. A reanalysis of prior data, in combination with our recent study, support the van der Waals hypothesis of gecko adhesion, and contradict surface hydrophobicity as a predictor of adhesion force. Previously, we and our collaborators measured the force production of a single seta. Initial efforts to attach a seta failed because of improper 3D orientation. However, by simulating the dynamics of gecko limbs during climbing (based on force plate data) we discovered that, in single setae, a small normal preload, combined with a 5 μm displacement yielded a very large adhesive force of 200 microNewton (μN), 10 times that predicted by whole-animal measurements. 6.5 million setae of a single tokay gecko attached maximally could generate 130 kg force. This raises the question of how geckos manage to detach their feet in just 15 ms. We discovered that simply increasing the angle that the setal shaft makes with the substrate to 30° causes detachment. Understanding how simultaneous attachment and release of millions of setae are controlled will require an approach that integrates levels ranging from molecules to lizards.

  15. Silorane adhesive system: a case report.

    PubMed

    Ruschel, Vanessa Carla; Baratieri, Luiz Narciso; Monteiro Júnior, Sylvio; Andrada, Mauro Amaral Caldeira de

    2014-01-01

    Silorane-based composite resin requires a specific adhesive system: a 2-step self-etching adhesive. Clinical protocols are well established and are based on the principles of adhesion to mineralized dental tissues. In this paper, we present a clinical application of the silorane adhesive system in a class-II restoration using silorane-based composite resin.

  16. Fibrillar Adhesive for Climbing Robots

    NASA Technical Reports Server (NTRS)

    Pamess, Aaron; White, Victor E.

    2013-01-01

    A climbing robot needs to use its adhesive patches over and over again as it scales a slope. Replacing the adhesive at each step is generally impractical. If the adhesive or attachment mechanism cannot be used repeatedly, then the robot must carry an extra load of this adhesive to apply a fresh layer with each move. Common failure modes include tearing, contamination by dirt, plastic deformation of fibers, and damage from loading/ unloading. A gecko-like fibrillar adhesive has been developed that has been shown useful for climbing robots, and may later prove useful for grasping, anchoring, and medical applications. The material consists of a hierarchical fibrillar structure that currently contains two levels, but may be extended to three or four levels in continuing work. The contacting level has tens of thousands of microscopic fibers made from a rubberlike material that bend over and create intimate contact with a surface to achieve maximum van der Waals forces. By maximizing the real area of contact that these fibers make and minimizing the bending energy necessary to achieve that contact, the net amount of adhesion has been improved dramatically.

  17. Neuropeptides, via specific receptors, regulate T cell adhesion to fibronectin.

    PubMed

    Levite, M; Cahalon, L; Hershkoviz, R; Steinman, L; Lider, O

    1998-01-15

    The ability of T cells to adhere to and interact with components of the blood vessel walls and the extracellular matrix is essential for their extravasation and migration into inflamed sites. We have found that the beta1 integrin-mediated adhesion of resting human T cells to fibronectin, a major glycoprotein component of the extracellular matrix, is induced by physiologic concentrations of three neuropeptides: calcitonin gene-related protein (CGRP), neuropeptide Y, and somatostatin; each acts via its own specific receptor on the T cell membrane. In contrast, substance P (SP), which coexists with CGRP in the majority of peripheral endings of sensory nerves, including those innervating the lymphoid organs, blocks T cell adhesion to fibronectin when induced by CGRP, neuropeptide Y, somatostatin, macrophage inflammatory protein-1beta, and PMA. Inhibition of T cell adhesion was obtained both by the intact SP peptide and by its 1-4 N-terminal and its 4-11, 5-11, and 6-11 C-terminal fragments, used at similar nanomolar concentrations. The inhibitory effects of the parent SP peptide and its fragments were abrogated by an SP NK-1 receptor antagonist, suggesting they all act through the same SP NK-1 receptor. These findings suggest that neuropeptides, by activating their specific T cell-expressed receptors, can provide the T cells with both positive (proadhesive) and negative (antiadhesive) signals and thereby regulate their function. Thus, neuropeptides may influence diverse physiologic processes involving integrins, including leukocyte-mediated migration and inflammation. PMID:9551939

  18. Focal adhesion kinase

    PubMed Central

    Stone, Rebecca L; Baggerly, Keith A; Armaiz-Pena, Guillermo N; Kang, Yu; Sanguino, Angela M; Thanapprapasr, Duangmani; Dalton, Heather J; Bottsford-Miller, Justin; Zand, Behrouz; Akbani, Rehan; Diao, Lixia; Nick, Alpa M; DeGeest, Koen; Lopez-Berestein, Gabriel; Coleman, Robert L; Lutgendorf, Susan; Sood, Anil K

    2014-01-01

    This investigation describes the clinical significance of phosphorylated focal adhesion kinase (FAK) at the major activating tyrosine site (Y397) in epithelial ovarian cancer (EOC) cells and tumor-associated endothelial cells. FAK gene amplification as a mechanism for FAK overexpression and the effects of FAK tyrosine kinase inhibitor VS-6062 on tumor growth, metastasis, and angiogenesis were examined. FAK and phospho-FAKY397 were quantified in tumor (FAK-T; pFAK-T) and tumor-associated endothelial (FAK-endo; pFAK-endo) cell compartments of EOCs using immunostaining and qRT-PCR. Associations between expression levels and clinical variables were evaluated. Data from The Cancer Genome Atlas were used to correlate FAK gene copy number and expression levels in EOC specimens. The in vitro and in vivo effects of VS-6062 were assayed in preclinical models. FAK-T and pFAK-T overexpression was significantly associated with advanced stage disease and increased microvessel density (MVD). High MVD was observed in tumors with elevated endothelial cell FAK (59%) and pFAK (44%). Survival was adversely affected by FAK-T overexpression (3.03 vs 2.06 y, P = 0.004), pFAK-T (2.83 vs 1.78 y, P < 0.001), and pFAK-endo (2.33 vs 2.17 y, P = 0.005). FAK gene copy number was increased in 34% of tumors and correlated with expression levels (P < 0.001). VS-6062 significantly blocked EOC and endothelial cell migration as well as endothelial cell tube formation in vitro. VS-6062 reduced mean tumor weight by 56% (P = 0.005), tumor MVD by 40% (P = 0.0001), and extraovarian metastasis (P < 0.01) in orthotopic EOC mouse models. FAK may be a unique therapeutic target in EOC given the dual anti-angiogenic and anti-metastatic potential of FAK inhibitors. PMID:24755674

  19. Investigation of organic adhesives for hybrid microcircuits

    NASA Technical Reports Server (NTRS)

    Perkins, K. L.; Licari, J. J.

    1975-01-01

    The properties of organic adhesives were investigated to acquire information for a guideline document regarding the selection of adhesives for use in high reliability hybrid microcircuits. Specifically, investigations were made of (1) alternate methods for determining the outgassing of cured adhesives, (2) effects of long term aging at 150 C on the electrical properties of conductive adhesives, (3) effects of shelf life age on adhesive characteristics, (4) bond strengths of electrically conductive adhesives on thick film gold metallization, (5) a copper filled adhesive, (6) effects of products outgassed from cured adhesives on device electrical parameters, (7) metal migration from electrically conductive adhesives, and (8) ionic content of electrically insulative adhesives. The tests performed during these investigations are described, and the results obtained are discussed.

  20. Plasma polymerization for cell adhesive/anti-adhesive implant coating

    NASA Astrophysics Data System (ADS)

    Meichsner, Juergen; Testrich, Holger; Rebl, Henrike; Nebe, Barbara

    2015-09-01

    Plasma polymerization of ethylenediamine (C2H8N2, EDA) and perfluoropropane (C3F8, PFP) with admixture of argon and hydrogen, respectively, was studied using an asymmetric 13.56 MHz CCP. The analysis of the plasma chemical gas phase processes for stable molecules revealed consecutive reactions: C2H8N2 consumption, intermediate product NH3, and main final product HCN. In C3F8- H2 plasma the precursor molecule C3F8 and molecular hydrogen are consumed and HF as well as CF4 and C2F6 are found as main gaseous reaction products. The deposited plasma polymer films on the powered electrode are strongly cross-linked due to ion bombardment. The stable plasma polymerized films from EDA are characterized by high content of nitrogen with N/C ratio of about 0.35. The plasma polymerized fluorocarbon film exhibit a reduced F/C ratio of about 1.2. Adhesion tests with human osteoblast cell line MG-63 on coated Ti6Al4V samples (polished) compared with uncoated reference sample yielded both, the enhanced cell adhesion for plasma polymerized EDA and significantly reduced cell adhesion for fluorocarbon coating, respectively. Aging of the plasma polymerized EDA film, in particular due to the reactions with oxygen from air, showed no significant change in the cell adhesion. The fluorocarbon coating with low cell adhesion is of interest for temporary implants. Funded by the Campus PlasmaMed.

  1. Optimizing Adhesive Design by Understanding Compliance.

    PubMed

    King, Daniel R; Crosby, Alfred J

    2015-12-23

    Adhesives have long been designed around a trade-off between adhesive strength and releasability. Geckos are of interest because they are the largest organisms which are able to climb utilizing adhesive toepads, yet can controllably release from surfaces and perform this action over and over again. Attempting to replicate the hierarchical, nanoscopic features which cover their toepads has been the primary focus of the adhesives field until recently. A new approach based on a scaling relation which states that reversible adhesive force capacity scales with (A/C)(1/2), where A is the area of contact and C is the compliance of the adhesive, has enabled the creation of high strength, reversible adhesives without requiring high aspect ratio, fibrillar features. Here we introduce an equation to calculate the compliance of adhesives, and utilize this equation to predict the shear adhesive force capacity of the adhesive based on the material components and geometric properties. Using this equation, we have investigated important geometric parameters which control force capacity and have shown that by controlling adhesive shape, adhesive force capacity can be increased by over 50% without varying pad size. Furthermore, we have demonstrated that compliance of the adhesive far from the interface still influences shear adhesive force capacity. Utilizing this equation will allow for the production of adhesives which are optimized for specific applications in commercial and industrial settings. PMID:26618537

  2. Optimizing Adhesive Design by Understanding Compliance.

    PubMed

    King, Daniel R; Crosby, Alfred J

    2015-12-23

    Adhesives have long been designed around a trade-off between adhesive strength and releasability. Geckos are of interest because they are the largest organisms which are able to climb utilizing adhesive toepads, yet can controllably release from surfaces and perform this action over and over again. Attempting to replicate the hierarchical, nanoscopic features which cover their toepads has been the primary focus of the adhesives field until recently. A new approach based on a scaling relation which states that reversible adhesive force capacity scales with (A/C)(1/2), where A is the area of contact and C is the compliance of the adhesive, has enabled the creation of high strength, reversible adhesives without requiring high aspect ratio, fibrillar features. Here we introduce an equation to calculate the compliance of adhesives, and utilize this equation to predict the shear adhesive force capacity of the adhesive based on the material components and geometric properties. Using this equation, we have investigated important geometric parameters which control force capacity and have shown that by controlling adhesive shape, adhesive force capacity can be increased by over 50% without varying pad size. Furthermore, we have demonstrated that compliance of the adhesive far from the interface still influences shear adhesive force capacity. Utilizing this equation will allow for the production of adhesives which are optimized for specific applications in commercial and industrial settings.

  3. Innovative Electrostatic Adhesion Technologies

    NASA Astrophysics Data System (ADS)

    Gagliano, L.; Bryan, T.; Williams, S.; McCoy, B.; MacLeod, T.

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and development

  4. Innovative Electrostatic Adhesion Technologies

    NASA Technical Reports Server (NTRS)

    Bryan, Tom; Macleod, Todd; Gagliano, Larry; Williams, Scott; McCoy, Brian

    2015-01-01

    Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA gripper pad surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and

  5. Elastocapilllarity in insect adhesion: the case of beetle adhesive hair

    NASA Astrophysics Data System (ADS)

    Gernay, Sophie; Gilet, Tristan; Lambert, Pierre; Federle, Walter

    2014-11-01

    The feet of many insects are covered with dense arrays of hair-like structures called setae. Liquid capillary bridges at the tip of these micrometric structures are responsible for the controlled adhesion of the insect on a large variety of substrates. The resulting adhesion force can exceed several times the body weight of the insect. The high aspect-ratio of setae suggests that flexibility is a key ingredient in this capillary-based adhesion mechanism. There is indeed a strong coupling between their elastic deformation and the shape of the liquid meniscus. In this experimental work, we observe and quantify the local deflection of dock beetle seta tips under perpendicular loading using interference microscopy. Our results are then interpreted in the light of an analytic model of elastocapillarity. This research has been funded by the FRIA/FNRS and the Interuniversity Attraction Poles Programme (IAP 7/38 MicroMAST) initiated by the Belgian Science Policy Office.

  6. Interactions between Plasmodium falciparum skeleton-binding protein 1 and the membrane skeleton of malaria-infected red blood cells

    PubMed Central

    Buckingham, Donna W.; Blanc, Lionel; Hale, John; Guo, Xinhua; Pei, Xinhong; Herrmann, Susann; Hanssen, Eric G.; Coppel, Ross L.; Mohandas, Narla; An, Xiuli; Cooke, Brian M.

    2015-01-01

    During development inside red blood cells (RBCs), Plasmodium falciparum malaria parasites export proteins that associate with the RBC membrane skeleton. These interactions cause profound changes to the biophysical properties of RBCs that underpin the often severe and fatal clinical manifestations of falciparum malaria. P. falciparum erythrocyte membrane protein 1 (PfEMP1) is one such exported parasite protein that plays a major role in malaria pathogenesis since its exposure on the parasitised RBC surface mediates their adhesion to vascular endothelium and placental syncytioblasts. En route to the RBC membrane skeleton, PfEMP1 transiently associates with Maurer's clefts (MCs), parasite-derived membranous structures in the RBC cytoplasm. We have previously shown that a resident MC protein, skeleton-binding protein 1 (SBP1), is essential for the placement of PfEMP1 onto the RBC surface and hypothesised that the function of SBP1 may be to target MCs to the RBC membrane. Since this would require additional protein interactions, we set out to identify binding partners for SBP1. Using a combination of approaches, we have defined the region of SBP1 that binds specifically to defined subdomains of two major components of the RBC membrane skeleton, protein 4.1R and spectrin. We show that these interactions serve as one mechanism to anchor MCs to the RBC membrane skeleton, however, while they appear to be necessary, they are not sufficient for the translocation of PfEMP1 onto the RBC surface. The N-terminal domain of SBP1 that resides within the lumen of MCs clearly plays an essential, but presently unknown role in this process. PMID:25883090

  7. Interactions between Plasmodium falciparum skeleton-binding protein 1 and the membrane skeleton of malaria-infected red blood cells.

    PubMed

    Kats, Lev M; Proellocks, Nicholas I; Buckingham, Donna W; Blanc, Lionel; Hale, John; Guo, Xinhua; Pei, Xinhong; Herrmann, Susann; Hanssen, Eric G; Coppel, Ross L; Mohandas, Narla; An, Xiuli; Cooke, Brian M

    2015-07-01

    During development inside red blood cells (RBCs), Plasmodium falciparum malaria parasites export proteins that associate with the RBC membrane skeleton. These interactions cause profound changes to the biophysical properties of RBCs that underpin the often severe and fatal clinical manifestations of falciparum malaria. P. falciparum erythrocyte membrane protein 1 (PfEMP1) is one such exported parasite protein that plays a major role in malaria pathogenesis since its exposure on the parasitised RBC surface mediates their adhesion to vascular endothelium and placental syncytioblasts. En route to the RBC membrane skeleton, PfEMP1 transiently associates with Maurer's clefts (MCs), parasite-derived membranous structures in the RBC cytoplasm. We have previously shown that a resident MC protein, skeleton-binding protein 1 (SBP1), is essential for the placement of PfEMP1 onto the RBC surface and hypothesised that the function of SBP1 may be to target MCs to the RBC membrane. Since this would require additional protein interactions, we set out to identify binding partners for SBP1. Using a combination of approaches, we have defined the region of SBP1 that binds specifically to defined sub-domains of two major components of the RBC membrane skeleton, protein 4.1R and spectrin. We show that these interactions serve as one mechanism to anchor MCs to the RBC membrane skeleton, however, while they appear to be necessary, they are not sufficient for the translocation of PfEMP1 onto the RBC surface. The N-terminal domain of SBP1 that resides within the lumen of MCs clearly plays an essential, but presently unknown role in this process.

  8. Capillarity-based switchable adhesion.

    PubMed

    Vogel, Michael J; Steen, Paul H

    2010-02-23

    Drawing inspiration from the adhesion abilities of a leaf beetle found in nature, we have engineered a switchable adhesion device. The device combines two concepts: The surface tension force from a large number of small liquid bridges can be significant (capillarity-based adhesion) and these contacts can be quickly made or broken with electronic control (switchable). The device grabs or releases a substrate in a fraction of a second via a low-voltage pulse that drives electroosmotic flow. Energy consumption is minimal because both the grabbed and released states are stable equilibria that persist with no energy added to the system. Notably, the device maintains the integrity of an array of hundreds to thousands of distinct interfaces during active reconfiguration from droplets to bridges and back, despite the natural tendency of the liquid toward coalescence. We demonstrate the scaling of adhesion strength with the inverse of liquid contact size. This suggests that strengths approaching those of permanent bonding adhesives are possible as feature size is scaled down. In addition, controllability is fast and efficient because the attachment time and required voltage also scale down favorably. The device features compact size, no solid moving parts, and is made of common materials.

  9. Capillarity-based switchable adhesion

    PubMed Central

    Vogel, Michael J.; Steen, Paul H.

    2010-01-01

    Drawing inspiration from the adhesion abilities of a leaf beetle found in nature, we have engineered a switchable adhesion device. The device combines two concepts: The surface tension force from a large number of small liquid bridges can be significant (capillarity-based adhesion) and these contacts can be quickly made or broken with electronic control (switchable). The device grabs or releases a substrate in a fraction of a second via a low-voltage pulse that drives electroosmotic flow. Energy consumption is minimal because both the grabbed and released states are stable equilibria that persist with no energy added to the system. Notably, the device maintains the integrity of an array of hundreds to thousands of distinct interfaces during active reconfiguration from droplets to bridges and back, despite the natural tendency of the liquid toward coalescence. We demonstrate the scaling of adhesion strength with the inverse of liquid contact size. This suggests that strengths approaching those of permanent bonding adhesives are possible as feature size is scaled down. In addition, controllability is fast and efficient because the attachment time and required voltage also scale down favorably. The device features compact size, no solid moving parts, and is made of common materials. PMID:20133725

  10. High performance Cu adhesion coating

    SciTech Connect

    Lee, K.W.; Viehbeck, A.; Chen, W.R.; Ree, M.

    1996-12-31

    Poly(arylene ether benzimidazole) (PAEBI) is a high performance thermoplastic polymer with imidazole functional groups forming the polymer backbone structure. It is proposed that upon coating PAEBI onto a copper surface the imidazole groups of PAEBI form a bond with or chelate to the copper surface resulting in strong adhesion between the copper and polymer. Adhesion of PAEBI to other polymers such as poly(biphenyl dianhydride-p-phenylene diamine) (BPDA-PDA) polyimide is also quite good and stable. The resulting locus of failure as studied by XPS and IR indicates that PAEBI gives strong cohesive adhesion to copper. Due to its good adhesion and mechanical properties, PAEBI can be used in fabricating thin film semiconductor packages such as multichip module dielectric (MCM-D) structures. In these applications, a thin PAEBI coating is applied directly to a wiring layer for enhancing adhesion to both the copper wiring and the polymer dielectric surface. In addition, a thin layer of PAEBI can also function as a protection layer for the copper wiring, eliminating the need for Cr or Ni barrier metallurgies and thus significantly reducing the number of process steps.

  11. Interfacial adhesion: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Ferrante, John; Bozzolo, Guillermo H.; Finley, Clarence W.; Banerjea, Amitava

    1988-01-01

    Adhesion, the binding of different materials at an interface, is of general interest to many branches of technology, e.g., microelectronics, tribology, manufacturing, construction, etc. However, there is a lack of fundamental understanding of such diverse interfaces. In addition, experimental techniques generally have practical objectives, such as the achievement of sufficient strength to sustain mechanical or thermal effects and/or have the proper electronic properties. In addition, the theoretical description of binding at interfaces is quite limited, and a proper data base for such theoretical analysis does not exist. This presentation will review both experimental and theoretical aspects of adhesion in nonpolymer materials. The objective will be to delineate the critical parameters needed, governing adhesion testing along with an outline of testing objectives. A distinction will be made between practical and fundamental objectives. Examples are given where interfacial bonding may govern experimental consideration. The present status of theory is presented along wiith recommendations for future progress and needs.

  12. Interfacial adhesion - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Ferrante, John; Banerjea, Amitava; Bozzolo, Guillermo H.; Finley, Clarence W.

    1988-01-01

    Adhesion, the binding of different materials at an interface, is of general interest to many branches of technology, e.g., microelectronics, tribology, manufacturing, construction, etc. However, there is a lack of fundamental understanding of such diverse interfaces. In addition, experimental techniques generally have practical objectives, such as the achievement of sufficient strength to sustain mechanical or thermal effects and/or have the proper electronic properties. In addition, the theoretical description of binding at interfaces is quite limited, and a proper data base for such theoretical analysis does not exist. This presentation will review both experimental and theoretical aspects of adhesion in nonpolymer materials. The objective will be to delineate the critical parameters needed, governing adhesion testing along with an outline of testing objectives. A distinction will be made between practical and fundamental objectives. Examples are given where interfacial bonding may govern experimental consideration. The present status of theory is presented along with recommendations for future progress and needs.

  13. Platelet adhesiveness after blood donation.

    PubMed

    Pegrum, G D; Harrison, K M; Shaw, S

    1971-03-13

    Platelet adhesiveness to glass was measured in healthy blood donors at the time of and eight days after donating 500 ml of blood. By a whole blood method a highly significant increase was found whereas by a method using platelet-rich plasma with added adenosine diphosphate there was only a slightly significant increase. The discrepancy suggested that changes in the red cell population might influence the results. Packed red cells from 19 blood donors obtained at the time of donation and eight days later were mixed with fresh pooled platelets from the same independent persons on each occasion. The whole blood platelet adhesiveness on this mixture showed an increase in every case after blood donation. It is postulated that the increased adhesiveness is influenced by the presence of young red cells.

  14. UV curable pressure sensitive adhesives

    SciTech Connect

    Glotfelter, C.A.

    1995-12-01

    Pressure sensitive adhesives (PSA`s) have become a ubiquitous element in our society, so much so, that the relative status of a society can be determined by the per capita consumption of PSA`s. We discuss new monomers as components of PSA formulations which enable adhesion to be achieved on a variety of substrates. Since solventless coating systems are desirable, the UV PSA market is of utmost importance to meeting the strict environmental guidelines now being imposed worldwide. In addition, highly ethoxylated monomers have shown promise in water dispersed PSA formulations, and a self-emulsifying acrylate monomer has been developed to offer dispersive abilities without using traditional emulsifying agents. This talk will focus on the effects of the materials described on properties of adhesive strength and shear strength in UV PSA formulations.

  15. Adhesive capsulitis: a case report

    PubMed Central

    Kazemi, Mohsen

    2000-01-01

    Adhesive capsulitis or frozen shoulder is an uncommon entity in athletes. However, it is a common cause of shoulder pain and disability in the general population. Although it is a self limiting ailment, its rather long, restrictive and painful course forces the affected person to seek treatment. Conservative management remains the mainstay treatment of adhesive capsulitis. This includes chiropractic manipulation of the shoulder, therapeutic modalities, mobilization, exercise, soft tissue therapy, nonsteroidal anti-inflammatory drugs, and steroid injections. Manipulation under anesthesia is advocated when the conservative treatment fails. A case of secondary adhesive capsulitis in a forty-seven-year-old female recreational squash player is presented to illustrate clinical presentation, diagnosis, radiographic assessment and conservative chiropractic management. The patient’s shoulder range of motion was full and pain free with four months of conservative chiropractic care. ImagesFigure 1Figure 2Figure 3

  16. A novel addition polyimide adhesive

    NASA Technical Reports Server (NTRS)

    St.clair, T. L.; Progar, D. J.

    1981-01-01

    An addition polyimide adhesive, LARC 13, was developed which shows promise for bonding both titanium and composites for applications which require service temperatures in excess of 533 K. The LARC 13 is based on an oligomeric bis nadimide containing a meta linked aromatic diamine. The adhesive melts prior to polymerization due to its oligomeric nature, thereby allowing it to be processed at 344 kPa or less. Therefore, LARC 13 is ideal for the bonding of honeycomb sandwich structures. After melting, the resin thermosets during the cure of the nadic endcaps to a highly crosslinked system. Few volatiles are evolved, thus allowing large enclosed structures to be bonded. Preparation of the adhesive as well as bonding, aging, and testing of lap shear and honeycomb samples are discussed.

  17. Adhesive, elastomeric gel impregnating composition

    DOEpatents

    Shaw, David Glenn; Pollard, John Randolph; Brooks, Robert Aubrey

    2002-01-01

    An improved capacitor roll with alternating film and foil layers is impregnated with an adhesive, elastomeric gel composition. The gel composition is a blend of a plasticizer, a polyol, a maleic anhydride that reacts with the polyol to form a polyester, and a catalyst for the reaction. The impregnant composition is introduced to the film and foil layers while still in a liquid form and then pressure is applied to aid with impregnation. The impregnant composition is cured to form the adhesive, elastomeric gel. Pressure is maintained during curing.

  18. Dual-Mode Adhesive Pad

    NASA Technical Reports Server (NTRS)

    Hartz, Leslie

    1994-01-01

    Tool helps worker grip and move along large, smooth structure with no handgrips or footholds. Adheres to surface but easily released by actuating simple mechanism. Includes handle and segmented contact-adhesive pad. Bulk of pad made of soft plastic foam conforming to surface of structure. Each segment reinforced with rib. In sticking mode, ribs braced by side catches. In peeling mode, side catches retracted, and segmented adhesive pad loses its stiffness. Modified versions useful in inspecting hulls of ships and scaling walls in rescue operations.

  19. Protein adhesion force dynamics and single adhesion events.

    PubMed Central

    Sagvolden, G

    1999-01-01

    Using the manipulation force microscope, a novel atomic force microscope, the adhesion forces of bovine serum albumin, myoglobin, ferritin, and lysozyme proteins to glass and polystyrene substrates were characterized by following the force necessary to displace an adsorbed protein-covered microsphere over several orders of magnitude in time. This force was consistent with a power law with exponent a = 0.37 +/- 0.03 on polystyrene, indicating that there is no typical time scale for adhesion on this substrate. On glass, the rate of adhesion depended strongly on protein charge. Forces corresponding to single protein adhesion events were identified. The typical rupture force of a single lysozyme, ferritin, bovine serum albumin, and myoglobin protein adhering to glass was estimated to be 90 +/- 10 pN, 115 +/- 13 pN, 277 +/- 44 pN, and 277 +/- 44 pN, respectively, using a model of the experimental system. These forces, as well as the force amplitudes on hydrophobic polystyrene, correlate with protein stiffness. PMID:10388777

  20. [FTIR spectroscopic studies of facial prosthetic adhesives].

    PubMed

    Kang, Biao; Yang, Qing-fang; Liang, Jian-feng; Zhao, Yi-min

    2008-10-01

    According to the composition of the traditional facial prosthetic adhesives, most of adhesives can be classified into two categories: acrylic polymer-based adhesive and silicone-based adhesive. In previous studies, measurements of various mechanical bond strengths were carried out, whereas the functional groups of the adhesives were evaluated seldom during the adhesion. In the present study the analysis of two facial prosthetic adhesives (Epithane and Secure Adhesive) was carried out by using infrared spectroscopy. Two adhesives in the form of fluid or semisolid were submitted to FTIR spectroscopy, respectively. The results showed that water and ammonia residue volatilized during the solidification of Epithane, and absorption peak reduction of carbonyl was due to the volatilization of acetate vinyl from Secure Adhesive. Similar silicone functional groups both in the silicone-based adhesive and in silicone elastomer could be the key to higher bond strength between silicone elastomer and skin with silicone-based adhesive. The position, shape of main absorption peaks of three adhesives didn't change, which showing that their main chemicals and basic structures didn't change during solidification. PMID:19123392

  1. Fibrinogen up-regulates the expression of monocyte chemoattractant protein 1 in human saphenous vein endothelial cells.

    PubMed Central

    Harley, S L; Powell, J T

    1999-01-01

    High concentrations of fibrinogen in plasma have been associated with an increased risk of saphenous vein graft pathology. We have investigated the ability of fibrinogen to up-regulate the expression of monocyte chemoattractant protein 1 (MCP-1) in cultured human saphenous vein endothelial cells (HSVEC) isolated from saphenous vein. Increasing concentrations of fibrinogen (0-4 microM) stimulated a 20-fold increase in MCP-1 secretion within 4 h. Incubation of HSVEC with 2 microM fibrinogen for 4 h also caused a 2-fold increase in the MCP-1-to-glyceraldehyde-3-phosphate dehydrogenase mRNA ratio. The fibrinogen-mediated MCP-1 secretion fell to basal levels after preincubation of HSVEC with the complex of fibrinogen fragments D and E but remained unchanged after preincubation of HSVEC with either fibrinogen fragment E, s-ICAM-1 or the pentapeptide GRGDV. In contrast, fibrinogen fragment D acted as a potent inhibitor of fibrinogen-mediated MCP-1 secretion. Labelled fibrinogen fragment D bound to HSVEC with a K(d) of 6.5 microM. These findings indicate that fibrinogen, at physiological concentrations, uses an epitope on the fibrinogen D domain to bind to a receptor on HSVEC to up-regulate MCP-1 expression and secretion. This receptor seems to be distinct from intercellular adhesion molecule 1 and the integrins previously recognized as fibrinogen receptors. PMID:10417339

  2. Epidermal growth factor, latrophilin, and seven transmembrane domain-containing protein 1 marker, a novel angiogenesis marker

    PubMed Central

    Serban, Florentina; Artene, Stefan-Alexandru; Georgescu, Ada Maria; Purcaru, Stefana Oana; Tache, Daniela Elise; Alexandru, Oana; Dricu, Anica

    2015-01-01

    Epidermal growth factor, latrophilin, and seven transmembrane domain-containing protein 1 on chromosome 1 (ELTD1), an orphan adhesion G-protein coupled receptor, was reported as a regulator of angiogenesis, also involved in cancer progression and development. More recently, ELTD1 was identified as a potential new tumor marker for high-grade glioma. ELTD1, belongs to the G-protein coupled receptor superfamily that comprises the biggest receptor family in the human genome. Following the discovery of ELTD1 almost a decade ago, only a few research groups have attempted to find its role in normal and tumor cells, important information about this receptor remaining still unknown. The ELTD1 ligand has not currently been identified and intracellular signaling studies have not yet been performed in normal or tumor cells. Although the current published data on ELTD1 function and structure are rather limited, this receptor seems to be very important, not only as biomarker, but also as molecular target in glioblastoma. This review summarizes and discusses the current knowledge on ELTD1 structure, function, and its role in both physiological and tumoral angiogenesis. PMID:26719704

  3. New adhesive withstands temperature extremes

    NASA Technical Reports Server (NTRS)

    Park, J. J.; Seidenberg, B.

    1978-01-01

    Adhesive, developed for high-temperature components aboard satellites, is useful at both high and low temperatures and exhibits low-vacuum volatility and low shrinkage. System uses polyfunctional epoxy with high aromatic content, low equivalent weight, and more compact polymer than conventional bisphenol A tape.

  4. Candida biofilms: is adhesion sexy?

    PubMed

    Soll, David R

    2008-08-26

    The development of Candida albicans biofilms requires two types of adhesion molecule - the Als proteins and Hwp1. Mutational analyses have recently revealed that these molecules play complementary roles, and their characteristics suggest that they may have evolved from primitive mating agglutinins.

  5. Candida biofilms: is adhesion sexy?

    PubMed

    Soll, David R

    2008-08-26

    The development of Candida albicans biofilms requires two types of adhesion molecule - the Als proteins and Hwp1. Mutational analyses have recently revealed that these molecules play complementary roles, and their characteristics suggest that they may have evolved from primitive mating agglutinins. PMID:18727911

  6. Photoresist substrate having robust adhesion

    DOEpatents

    Dentinger, Paul M.

    2005-07-26

    A substrate material for LIGA applications w hose general composition is Ti/Cu/Ti/SiO.sub.2. The SiO.sub.2 is preferably applied to the Ti/Cu/Ti wafer as a sputtered coating, typically about 100 nm thick. This substrate composition provides improved adhesion for epoxy-based photoresist materials, and particularly the photoresist material SU-8.

  7. Unfolding Grammars in Adhesive Categories

    NASA Astrophysics Data System (ADS)

    Baldan, Paolo; Corradini, Andrea; Heindel, Tobias; König, Barbara; Sobociński, Paweł

    We generalize the unfolding semantics, previously developed for concrete formalisms such as Petri nets and graph grammars, to the abstract setting of (single pushout) rewriting over adhesive categories. The unfolding construction is characterized as a coreflection, i.e. the unfolding functor arises as the right adjoint to the embedding of the category of occurrence grammars into the category of grammars.

  8. Fluorescence Reveals Contamination From Adhesives

    NASA Technical Reports Server (NTRS)

    Nikolia, William

    1992-01-01

    Contamination of nearby surfaces from ingredients in some adhesive materials detected by ultraviolet illumination and observation of resulting fluorescence. Identification of contaminants via telltale fluorescence not new; rather, significance lies in method of implementation and potential extension to wider variety of materials and applications.

  9. Computational Chemistry of Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Phillips, Donald H.

    1999-01-01

    This investigation is intended to determine the electrical mechanical, and chemical properties of adhesive bonds at the molecular level. The initial determinations will be followed by investigations of the effects of environmental effects on the chemistry and properties of the bond layer.

  10. Tackifier Dispersions to Make Pressure Sensitive Adhesives

    SciTech Connect

    2003-02-01

    Development of new processes for tackifier dispersion could improve the production of pressure sensitive adhesives. Pressure sensitive adhesives (PSAs) have the ability to adhere to different surfaces with manual or finger pressure.

  11. Disaccharides generated from heparan sulphate or heparin modulate chemokine-induced T-cell adhesion to extracellular matrix.

    PubMed

    Hershkoviz, R; Schor, H; Ariel, A; Hecht, I; Cohen, I R; Lider, O; Cahalon, L

    2000-01-01

    We have found previously that disaccharides (DS) enzymatically generated from heparin or heparan sulphate can modulate tumour necrosis factor-alpha (TNF-alpha) secretion from immune cells in vitro and cell-mediated immune reactions in vivo. Here, we show that such DS can modulate the adhesion and migration of human T cells. We found that certain heparin- and heparan sulphate-derived DS induced, in a dose-dependent manner, the adhesion of human T cells to both extracellular matrix (ECM) and immobilized fibronectin (FN); maximal T-cell adhesion occurred with 1 ng/ml of DS. The levels of T-cell adhesion to ECM that were induced by the tested DS molecules resembled those induced by the prototypic chemokine, macrophage inflammatory protein 1beta (MIP-1beta). However, the kinetics of DS-induced T-cell adhesion to FN resembled that induced by phorbol myristate acetate (PMA), but not that induced by MIP-1beta. This adhesion appeared to involve beta1 integrin recognition and activation, and was associated with specific intracellular activation pathways. Although a first exposure of T cells to certain DS molecules appeared to result in cell adhesion, a subsequent exposure of T cells to pro-adhesive chemokines, such as MIP-1beta or RANTES, but not to other pro-adhesive stimuli, for example interleukin-2 or CD3 cross-linking, resulted in inhibition of T-cell adhesion to and chemotactic migration through FN. Hence, we propose that the breakdown products of tissues generated by inflammatory enzymes are part of an intrinsic functional programme, and not necessarily molecular waste. Moreover, because the DS molecules exert their modulatory functions within a limited time, it appears that the historical encounters of the tissue-invading cells with the constituents of inflamed loci may dictate the cells' behaviour upon subsequent exposure to proinflammatory mediators. PMID:10651945

  12. Self-Adjustable Adhesion of Polyampholyte Hydrogels.

    PubMed

    Roy, Chanchal Kumar; Guo, Hong Lei; Sun, Tao Lin; Ihsan, Abu Bin; Kurokawa, Takayuki; Takahata, Masakazu; Nonoyama, Takayuki; Nakajima, Tasuku; Gong, Jian Ping

    2015-12-01

    Developing nonspecific, fast, and strong adhesives that can glue hydrogels and biotissues substantially promotes the application of hydrogels as biomaterials. Inspired by the ubiquitous adhesiveness of bacteria, it is reported that neutral polyampholyte hydrogels, through their self-adjustable surface, can show rapid, strong, and reversible adhesion to charged hydrogels and biological tissues through the Coulombic interaction.

  13. Nonwoven glass fiber mat reinforces polyurethane adhesive

    NASA Technical Reports Server (NTRS)

    Roseland, L. M.

    1967-01-01

    Nonwoven glass fiber mat reinforces the adhesive properties of a polyurethane adhesive that fastens hardware to exterior surfaces of aluminum tanks. The mat is embedded in the uncured adhesive. It ensures good control of the bond line and increases the peel strength.

  14. Ceramic adhesive restorations and biomimetic dentistry: tissue preservation and adhesion.

    PubMed

    Tirlet, Gil; Crescenzo, Hélène; Crescenzo, Dider; Bazos, Panaghiotis

    2014-01-01

    Thanks to sophisticated adhesive techniques in contemporary dentistry, and the development of composite and ceramic materials, it is possible to reproduce a biomimetic match between substitution materials and natural teeth substrates. Biomimetics or bio-emulation allows for the association of two fundamental parameters at the heart of current therapeutic treatments: tissue preservation and adhesion. This contemporary concept makes the retention of the integrity of the maximum amount of dental tissue possible, while offering exceptional clinical longevity, and maximum esthetic results. It permits the conservation of the biological, esthetic, biomechanical and functional properties of enamel and dentin. Today, it is clearly possible to develop preparations allowing for the conservation of the enamel and dentin in order to bond partial restorations in the anterior and posterior sectors therefore limiting, as Professor Urs Belser from Geneva indicates, "the replacement of previous deficient crowns and devitalized teeth whose conservation are justified but whose residual structural state are insufficient for reliable bonding."1 This article not only addresses ceramic adhesive restoration in the anterior area, the ambassadors of biomimetic dentistry, but also highlights the possibility of occasionally integrating one or two restorations at the heart of the smile as a complement to extensive rehabilitations that require more invasive treatment.

  15. Ceramic adhesive restorations and biomimetic dentistry: tissue preservation and adhesion.

    PubMed

    Tirlet, Gil; Crescenzo, Hélène; Crescenzo, Dider; Bazos, Panaghiotis

    2014-01-01

    Thanks to sophisticated adhesive techniques in contemporary dentistry, and the development of composite and ceramic materials, it is possible to reproduce a biomimetic match between substitution materials and natural teeth substrates. Biomimetics or bio-emulation allows for the association of two fundamental parameters at the heart of current therapeutic treatments: tissue preservation and adhesion. This contemporary concept makes the retention of the integrity of the maximum amount of dental tissue possible, while offering exceptional clinical longevity, and maximum esthetic results. It permits the conservation of the biological, esthetic, biomechanical and functional properties of enamel and dentin. Today, it is clearly possible to develop preparations allowing for the conservation of the enamel and dentin in order to bond partial restorations in the anterior and posterior sectors therefore limiting, as Professor Urs Belser from Geneva indicates, "the replacement of previous deficient crowns and devitalized teeth whose conservation are justified but whose residual structural state are insufficient for reliable bonding."1 This article not only addresses ceramic adhesive restoration in the anterior area, the ambassadors of biomimetic dentistry, but also highlights the possibility of occasionally integrating one or two restorations at the heart of the smile as a complement to extensive rehabilitations that require more invasive treatment. PMID:25126616

  16. Expression of adhesion molecules, chemokines and matrix metallo- proteinases (MMPs) in viable and degenerating stage of Taenia solium metacestode in swine neurocysticercosis.

    PubMed

    Singh, Satyendra K; Singh, Aloukick K; Prasad, Kashi N; Singh, Amrita; Singh, Avinash; Rai, Ravi P; Tripathi, Mukesh; Gupta, Rakesh K; Husain, Nuzhat

    2015-11-30

    Neurocysticercosis (NCC) is a parasitic infection of central nervous system (CNS). Expression of adhesion molecules, chemokines and matrix metalloproteinases (MMPs) were investigated on brain tissues surrounding viable (n=15) and degenerating cysticerci (n=15) of Taenia solium in swine by real-time RT-PCR and ELISA. Gelatin gel zymography was performed for MMPs activity. ICAM-1 (intercellular adhesion molecule-1), E-selectin, MIP-1α (macrophage inflammatory protein-1α), Eotaxin-1 and RANTES (regulated on activation, normal T cell expressed and secreted) were associated with degenerating cysticerci (cysts). However, VCAM-1 (vascular cell adhesion molecule-1), MCP-1 (monocyte chemotactic protein-1), MMP-2 and MMP-9 were associated with both viable and degenerating cysts. In conclusion, viable and degenerating cysticerci have different immune molecule profiles and role of these molecules in disease pathogenesis needs to be investigated. PMID:26412140

  17. Expression of adhesion molecules, chemokines and matrix metallo- proteinases (MMPs) in viable and degenerating stage of Taenia solium metacestode in swine neurocysticercosis.

    PubMed

    Singh, Satyendra K; Singh, Aloukick K; Prasad, Kashi N; Singh, Amrita; Singh, Avinash; Rai, Ravi P; Tripathi, Mukesh; Gupta, Rakesh K; Husain, Nuzhat

    2015-11-30

    Neurocysticercosis (NCC) is a parasitic infection of central nervous system (CNS). Expression of adhesion molecules, chemokines and matrix metalloproteinases (MMPs) were investigated on brain tissues surrounding viable (n=15) and degenerating cysticerci (n=15) of Taenia solium in swine by real-time RT-PCR and ELISA. Gelatin gel zymography was performed for MMPs activity. ICAM-1 (intercellular adhesion molecule-1), E-selectin, MIP-1α (macrophage inflammatory protein-1α), Eotaxin-1 and RANTES (regulated on activation, normal T cell expressed and secreted) were associated with degenerating cysticerci (cysts). However, VCAM-1 (vascular cell adhesion molecule-1), MCP-1 (monocyte chemotactic protein-1), MMP-2 and MMP-9 were associated with both viable and degenerating cysts. In conclusion, viable and degenerating cysticerci have different immune molecule profiles and role of these molecules in disease pathogenesis needs to be investigated.

  18. X-box-binding protein 1-modified neural stem cells for treatment of Parkinson's disease.

    PubMed

    Si, Lihui; Xu, Tianmin; Wang, Fengzhang; Liu, Qun; Cui, Manhua

    2012-04-01

    X-box-binding protein 1-transfected neural stem cells were transplanted into the right lateral ventricles of rats with rotenone-induced Parkinson's disease. The survival capacities and differentiation rates of cells expressing the dopaminergic marker tyrosine hydroxylase were higher in X-box-binding protein 1-transfected neural stem cells compared to non-transfected cells. Moreover, dopamine and 3,4-dihydroxyphenylacetic acid levels in the substantia nigra were significantly increased, α-synuclein expression was decreased, and neurological behaviors were significantly ameliorated in rats following transplantation of X-box-binding protein 1-transfected neural stem cells. These results indicate that transplantation of X-box-binding protein 1-transfected neural stem cells can promote stem cell survival and differentiation into dopaminergic neurons, increase dopamine and 3,4-dihydroxyphenylacetic acid levels, reduce α-synuclein aggregation in the substantia nigra, and improve the symptoms of Parkinson's disease in rats.

  19. Gecko adhesion pad: a smart surface?

    NASA Astrophysics Data System (ADS)

    Pesika, Noshir S.; Zeng, Hongbo; Kristiansen, Kai; Zhao, Boxin; Tian, Yu; Autumn, Kellar; Israelachvili, Jacob

    2009-11-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  20. Gecko adhesion pad: a smart surface?

    PubMed

    Pesika, Noshir S; Zeng, Hongbo; Kristiansen, Kai; Zhao, Boxin; Tian, Yu; Autumn, Kellar; Israelachvili, Jacob

    2009-11-18

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  1. Nanocapillary Adhesion between Parallel Plates.

    PubMed

    Cheng, Shengfeng; Robbins, Mark O

    2016-08-01

    Molecular dynamics simulations are used to study capillary adhesion from a nanometer scale liquid bridge between two parallel flat solid surfaces. The capillary force, Fcap, and the meniscus shape of the bridge are computed as the separation between the solid surfaces, h, is varied. Macroscopic theory predicts the meniscus shape and the contribution of liquid/vapor interfacial tension to Fcap quite accurately for separations as small as two or three molecular diameters (1-2 nm). However, the total capillary force differs in sign and magnitude from macroscopic theory for h ≲ 5 nm (8-10 diameters) because of molecular layering that is not included in macroscopic theory. For these small separations, the pressure tensor in the fluid becomes anisotropic. The components in the plane of the surface vary smoothly and are consistent with theory based on the macroscopic surface tension. Capillary adhesion is affected by only the perpendicular component, which has strong oscillations as the molecular layering changes.

  2. Particle adhesion in powder coating

    SciTech Connect

    Mazumder, M.K.; Wankum, D.L.; Knutson, M.; Williams, S.; Banerjee, S.

    1996-12-31

    Electrostatic powder coating is a widely used industrial painting process. It has three major advantages: (1) it provides high quality durable finish, (2) the process is environmentally friendly and does not require the use of organic solvents, and (3) it is economically competitive. The adhesion of electrostatically deposited polymer paint particles on the grounded conducting substrate depends upon many parameters: (a) particle size and shape distributions, (b) electrostatic charge distributions, (c) electrical resistivity, (d) dielectric strength of the particles, (e) thickness of the powder film, (f) presence and severity of the back corona, and (g) the conductivity and surface properties of the substrate. The authors present a model on the forces of deposition and adhesion of corona charged particles on conducting substrates.

  3. Nanocapillary Adhesion between Parallel Plates.

    PubMed

    Cheng, Shengfeng; Robbins, Mark O

    2016-08-01

    Molecular dynamics simulations are used to study capillary adhesion from a nanometer scale liquid bridge between two parallel flat solid surfaces. The capillary force, Fcap, and the meniscus shape of the bridge are computed as the separation between the solid surfaces, h, is varied. Macroscopic theory predicts the meniscus shape and the contribution of liquid/vapor interfacial tension to Fcap quite accurately for separations as small as two or three molecular diameters (1-2 nm). However, the total capillary force differs in sign and magnitude from macroscopic theory for h ≲ 5 nm (8-10 diameters) because of molecular layering that is not included in macroscopic theory. For these small separations, the pressure tensor in the fluid becomes anisotropic. The components in the plane of the surface vary smoothly and are consistent with theory based on the macroscopic surface tension. Capillary adhesion is affected by only the perpendicular component, which has strong oscillations as the molecular layering changes. PMID:27413872

  4. Host Selection of Microbiota via Differential Adhesion.

    PubMed

    McLoughlin, Kirstie; Schluter, Jonas; Rakoff-Nahoum, Seth; Smith, Adrian L; Foster, Kevin R

    2016-04-13

    The host epithelium is the critical interface with microbial communities, but the mechanisms by which the host regulates these communities are poorly understood. Here we develop the hypothesis that hosts use differential adhesion to select for and against particular members of their microbiota. We use an established computational, individual-based model to study the impact of host factors that regulate adhesion at the epithelial surface. Our simulations predict that host-mediated adhesion can increase the competitive advantage of microbes and create ecological refugia for slow-growing species. We show how positive selection via adhesion can be transformed into negative selection if the host secretes large quantities of a matrix such as mucus. Our work predicts that adhesion is a powerful mechanism for both positive and negative selection within the microbiota. We discuss molecules-mucus glycans and IgA-that affect microbe adhesion and identify testable predictions of the adhesion-as-selection model. PMID:27053168

  5. Theory of adhesion: Role of surface roughness

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.; Scaraggi, M.

    2014-09-01

    We discuss how surface roughness influences the adhesion between elastic solids. We introduce a Tabor number which depends on the length scale or magnification, and which gives information about the nature of the adhesion at different length scales. We consider two limiting cases relevant for (a) elastically hard solids with weak (or long ranged) adhesive interaction (DMT-limit) and (b) elastically soft solids with strong (or short ranged) adhesive interaction (JKR-limit). For the former cases we study the nature of the adhesion using different adhesive force laws (F ˜ u-n, n = 1.5-4, where u is the wall-wall separation). In general, adhesion may switch from DMT-like at short length scales to JKR-like at large (macroscopic) length scale. We compare the theory predictions to results of exact numerical simulations and find good agreement between theory and simulation results.

  6. Adhesive mechanisms in cephalopods: a review.

    PubMed

    von Byern, Janek; Klepal, Waltraud

    2006-01-01

    Several genera of cephalopods (Nautilus, Sepia, Euprymna and Idiosepius) produce adhesive secretions, which are used for attachment to the substratum, for mating and to capture prey. These adhesive structures are located in different parts of the body, viz. in the digital tentacles (Nautilus), in the ventral surface of the mantle and fourth arm pair (Sepia), in the dorsal epidermis (Euprymna), or in the dorsal mantle side and partly on the fins (Idiosepius). Adhesion in Sepia is induced by suction of dermal structures on the mantle, while for Nautilus, Euprymna and Idiosepius adhesion is probably achieved by chemical substances. Histochemical studies indicate that in Nautilus and Idiosepius secretory cells that appear to be involved in adhesion stain for carbohydrates and protein, whilst in Euprymna only carbohydrates are detectable. De-adhesion is either achieved by muscle contraction of the tentacles and mantle (Nautilus and Sepia) or by secretion of substances (Euprymna). The de-adhesive mechanism used by Idiosepius remains unknown. PMID:17110356

  7. Adhesion effects in contact interaction of solids

    NASA Astrophysics Data System (ADS)

    Goryacheva, Irina; Makhovskaya, Yulya

    2008-01-01

    An approach to solving problems of the interaction of axisymmetric elastic bodies in the presence of adhesion is developed. The different natures of adhesion, i.e. capillary adhesion, or molecular adhesion described by the Lennard-Jones potential are examined. The effect of additional loading of the interacting bodies outside the contact zone is also investigated. The approach is based on the representation of the pressure outside the contact zone arising from adhesion by a step function. The analytical solution is obtained and is used to analyze the influence of the form of the adhesion interaction potential, of the surface energy of interacting bodies or the films covering the bodies, their shapes (parabolic, higher power exponential function), volume of liquid in the meniscus, density of contact spots, of elastic modulus and the Poisson ratio on the characteristics of the interaction of the bodies in the presence of adhesion. To cite this article: I. Goryacheva, Y. Makhovskaya, C. R. Mecanique 336 (2008).

  8. Adhesive mechanisms in cephalopods: a review.

    PubMed

    von Byern, Janek; Klepal, Waltraud

    2006-01-01

    Several genera of cephalopods (Nautilus, Sepia, Euprymna and Idiosepius) produce adhesive secretions, which are used for attachment to the substratum, for mating and to capture prey. These adhesive structures are located in different parts of the body, viz. in the digital tentacles (Nautilus), in the ventral surface of the mantle and fourth arm pair (Sepia), in the dorsal epidermis (Euprymna), or in the dorsal mantle side and partly on the fins (Idiosepius). Adhesion in Sepia is induced by suction of dermal structures on the mantle, while for Nautilus, Euprymna and Idiosepius adhesion is probably achieved by chemical substances. Histochemical studies indicate that in Nautilus and Idiosepius secretory cells that appear to be involved in adhesion stain for carbohydrates and protein, whilst in Euprymna only carbohydrates are detectable. De-adhesion is either achieved by muscle contraction of the tentacles and mantle (Nautilus and Sepia) or by secretion of substances (Euprymna). The de-adhesive mechanism used by Idiosepius remains unknown.

  9. Approaching improved adhesive bonding repeatability

    NASA Astrophysics Data System (ADS)

    Schlette, Christian; Müller, Tobias; Roβmann, Jürgen; Brecher, Christian

    2016-03-01

    Today, the precision of micro-optics assembly is mostly limited by the accuracy of the bonding process ― and in the case of adhesive bonding by the prediction and compensation of adhesive shrinkage during curing. In this contribution, we present a novel approach to address adhesive bonding based on hybrid control system theory. In hybrid control, dynamic systems are described as "plants" which produce discrete and/or continuous outputs from given discrete and/or continuous inputs, thus yielding a hybrid state space description of the system. The task of hybrid controllers is to observe the plant and to generate a discrete and/or continuous input sequence that guides or holds the plant in a desired target state region while avoiding invalid or unwanted intermediate states. Our approach is based on a series of experiments carried out in order to analyze, define and decouple the dependencies of adhesive shrinkage on multiple parameters, such as application geometries, fixture forces and UV intensities. As some of the dependencies describe continuous effects (e.g. shrinkage from UV intensity) and other dependencies describe discrete state transitions (e.g. fixture removal during curing), the resulting model of the overall bonding process is a hybrid dynamic system in the general case. For this plant model, we then propose a concept of sampling-based parameter search as a basis to design suitable hybrid controllers, which have the potential to optimize process control for a selection of assembly steps, thus improving the repeatability of related production steps like beam-shaping optics or mounting of turning mirrors for fiber coupling.

  10. Polymer nanocarriers for dentin adhesion.

    PubMed

    Osorio, R; Osorio, E; Medina-Castillo, A L; Toledano, M

    2014-12-01

    To obtain more durable adhesion to dentin, and to protect collagen fibrils of the dentin matrix from degradation, calcium- and phosphate-releasing particles have been incorporated into the dental adhesive procedure. The aim of the present study was to incorporate zinc-loaded polymeric nanocarriers into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide calcium ions for mineral deposition within the resin-dentin bonded interface. PolymP- N : Active nanoparticles (nanoMyP) were zinc-loaded through 30-minute ZnCl2 immersion and tested for bioactivity by means of 7 days' immersion in simulated body fluid solution (the Kokubo test). Zinc-loading and calcium phosphate depositions were examined by scanning and transmission electron microscopy, elemental analysis, and x-ray diffraction. Nanoparticles in ethanol solution infiltrated into phosphoric-acid-etched human dentin and Single Bond (3M/ESPE) were applied to determine whether the nanoparticles interfered with bonding. Debonded sticks were analyzed by scanning electron microscopy. A metalloproteinase collagen degradation assay was also performed in resin-infiltrated dentin with and without nanoparticles, measuring C-terminal telopeptide of type I collagen (ICTP) concentration in supernatants, after 4 wk of immersion in artificial saliva. Numerical data were analyzed by analysis of variance (ANOVA) and Student-Newman-Keuls multiple comparisons tests (p < .05). Nanoparticles were effectively zinc-loaded and were shown to have a chelating effect, retaining calcium regardless of zinc incorporation. Nanoparticles failed to infiltrate demineralized intertubular dentin and remained on top of the hybrid layer, without altering bond strength. Calcium and phosphorus were found covering nanoparticles at the hybrid layer, after 24 h. Nanoparticle application in etched dentin also reduced MMP-mediated collagen degradation. Tested nanoparticles may be

  11. Culinary Medicine-Jalebi Adhesions.

    PubMed

    Kapoor, Vinay K

    2016-02-01

    Culinary terms have been used to describe anatomy (bean-shaped kidneys), pathology (strawberry gall bladder), clinical signs (café-au-lait spots), radiological images (sausage-shaped pancreas), etc. While Indian cuisine is popular all over the world, no Indian dish finds mention in medical terminology. In intra-abdominal adhesions, sometimes, the intestinal loops are so densely adherent that it is difficult to make out proximal from distal and it is impossible to separate them without injuring the bowel resulting in spill of contents-resection is the only option (Fig. 1). Jalebi, an Indian dessert, has a single long tubular strip of fried batter filled with sugary syrup so intertwined that it is impossible to discern its ends; if broken, the syrup spills out-the best way to relish it is to chew the whole piece (Fig. 2). Because of these similarities between them, I propose to name dense intra-abdominal adhesions as 'jalebi adhesions.' PMID:27186047

  12. Adhesive evaluation of new polyimides

    NASA Technical Reports Server (NTRS)

    Stclair, Terry L.; Progar, Donald J.

    1987-01-01

    During the past 10 to 15 years, the Materials Division at NASA Langley Research Center (LaRC) has developed several novel high temperature polyimide adhesives for anticipated needs of the aerospace industry. These developments have resulted from fundamental studies of structure-property relationships in polyimides. Recent research at LaRC has involved the synthesis and evaluation of copolyimides which incorporate both flexibilizing bridging groups and meta-linked benzene rings. The purpose was to develop systems based on low cost, readily available monomers. Two of these copolyimides evaluated as adhesives for bonding titanium alloy, Ti(6Al-4V), are identified as LARC-STPI and STPI-LARC-2. Lap shear strength (LSS) measurements were used to determine the strength and durability of the adhesive materials. LSS results are presented for LARC-TPI and LARC-STPI lap shear specimens thermally exposed in air at 232 C for up to 5000 hrs. LARC-TPI was shown to perform better than the copolymer LARC-STPI which exhibited poor thermooxidative performance possibly due to the amines used which would tend to oxidize easier than the benzophenone system in LARC-TPI.

  13. Increased erythrocyte adhesion to VCAM-1 during pulsatile flow: Application of a microfluidic flow adhesion bioassay

    PubMed Central

    White, Jennell; Lancelot, Moira; Sarnaik, Sharada; Hines, Patrick

    2015-01-01

    Abstract Sickle cell disease (SCD) is characterized by microvascular occlusion mediated by adhesive interactions of sickle erythrocytes (SSRBCs) to the endothelium. Most in vitro flow adhesion assays measure SSRBC adhesion during continuous flow, although in vivo SSRBC adhesive interactions occur during pulsatile flow. Using a well-plate microfluidic flow adhesion system, we demonstrate that isolated SSRBCs adhere to vascular cell adhesion molecule (VCAM-1) at greater levels during pulsatile versus continuous flow. A significant increase in adhesive interactions was observed between all pulse frequencies 1 Hz to 2 Hz (60–120 beats/min) when compared to non-pulsatile flow. Adhesion of isolated SSRBCs and whole blood during pulsatile flow was unaffected by protein kinase A (PKA) inhibition, and exposure of SSRBCs to pulsatile flow did not affect the intrinsic adhesive properties of SSRBCs. The cell type responsible for increased adhesion of whole blood varied from patient to patient. We conclude that low flow periods of the pulse cycle allow more adhesive interactions between sickle erythrocytes and VCAM-1, and sickle erythrocyte adhesion in the context of whole blood may better reflect physiologic cellular interactions. The microfluidic flow adhesion bioassay used in this study may have applications for clinical assessment of sickle erythrocyte adhesion during pulsatile flow. PMID:24898561

  14. The Plasmodium vivax Merozoite Surface Protein 1 Paralog Is a Novel Erythrocyte-Binding Ligand of P. vivax

    PubMed Central

    Cheng, Yang; Wang, Yue; Ito, Daisuke; Kong, Deok-Hoon; Ha, Kwon-Soo; Chen, Jun-Hu; Lu, Feng; Li, Jian; Wang, Bo; Takashima, Eizo; Sattabongkot, Jetsumon

    2013-01-01

    Merozoite surface protein 1 of Plasmodium vivax (PvMSP1), a glycosylphosphatidylinositol-anchored protein (GPI-AP), is a malaria vaccine candidate for P. vivax. The paralog of PvMSP1, named P. vivax merozoite surface protein 1 paralog (PvMSP1P; PlasmoDB PVX_099975), was recently identified and predicted as a GPI-AP. The similarities in genetic structural characteristics between PvMSP1 and PvMSP1P (e.g., size of open reading frames, two epidermal growth factor-like domains, and GPI anchor motif in the C terminus) led us to study this protein. In the present study, different regions of the PvMSP1P protein, demarcated based on the processed forms of PvMSP1, were expressed successfully as recombinant proteins [i.e., 83 (A, B, and C), 30, 38, 42, 33, and 19 fragments]. We studied the naturally acquired immune response against each fragment of recombinant PvMSP1P and the potential ability of each fragment to bind erythrocytes. The N-terminal fragment (83A) and two C-terminal fragments (33 and 19) reacted strongly with sera from P. vivax-infected patients, with 50 to 68% sensitivity and 95 to 96% specificity, respectively. Due to colocalization of PvMSP1P with PvMSP1, we supposed that PvMSP1P plays a similar role as PvMSP1 during erythrocyte invasion. An in vitro cytoadherence assay showed that PvMSP1P, especially the 19-kDa C-terminal region, could bind to erythrocytes. We also found that human sera from populations naturally exposed to vivax malaria and antisera obtained by immunization using the recombinant molecule PvMSP1P-19 inhibited in vitro binding of human erythrocytes to PvMSP1P-19. These results provide further evidence that the PvMSP1P might be an essential parasite adhesion molecule in the P. vivax merozoite and is a potential vaccine candidate against P. vivax. PMID:23460511

  15. Chitosan Adhesive Films for Photochemical Tissue Bonding

    NASA Astrophysics Data System (ADS)

    Lauto, Antonio; Mawad, Damia; Barton, Matthew; Piller, Sabine C.; Longo, Leonardo

    2011-08-01

    Photochemical tissue bonding (PTB) is a promising sutureless technique for tissue repair. PTB is often achieved by applying a solution of rose bengal (RB) between two tissue edges, which are irradiated by a green laser to crosslink collagen fibers with minimal heat production. In this study, RB has been incorporated in chitosan films to create a novel tissue adhesive that is laser-activated. Materials and Methods. Adhesive films, based on chitosan and containing ˜0.1wt% RB were manufactured and bonded to calf intestine by a solid state laser (wavelength = 532 nm, Fluence ˜110 J/cm2, spot size ˜5 mm). A single-column tensiometer, interfaced with a personal computer, tested the bonding strength. K-type thermocouples recorded the temperature (T) at the adhesive-tissue interface during laser irradiation. Human fibroblasts were also seeded on the adhesive and cultured for 48 hours to assess cell growth. Results and Conclusion. The RB-chitosan adhesive bonded firmly to the intestine (15±2 kPa, n = 31). The adhesion strength dropped to 0.5±0.1 kPa (n = 8) when the laser was not applied to the adhesive. The average temperature of the adhesive increased from 26 °C to 32 °C during laser exposure. Fibroblasts grew confluent on the adhesive without morphological changes. A new biocompatible chitosan adhesive has been developed that bonds photochemically to tissue with minimal temperature increase.

  16. Sundew adhesive: a naturally occurring hydrogel

    PubMed Central

    Huang, Yujian; Wang, Yongzhong; Sun, Leming; Agrawal, Richa; Zhang, Mingjun

    2015-01-01

    Bioadhesives have drawn increasing interest in recent years, owing to their eco-friendly, biocompatible and biodegradable nature. As a typical bioadhesive, sticky exudate observed on the stalked glands of sundew plants aids in the capture of insects and this viscoelastic adhesive has triggered extensive interests in revealing the implied adhesion mechanisms. Despite the significant progress that has been made, the structural traits of the sundew adhesive, especially the morphological characteristics in nanoscale, which may give rise to the viscous and elastic properties of this mucilage, remain unclear. Here, we show that the sundew adhesive is a naturally occurring hydrogel, consisting of nano-network architectures assembled with polysaccharides. The assembly process of the polysaccharides in this hydrogel is proposed to be driven by electrostatic interactions mediated with divalent cations. Negatively charged nanoparticles, with an average diameter of 231.9 ± 14.8 nm, are also obtained from this hydrogel and these nanoparticles are presumed to exert vital roles in the assembly of the nano-networks. Further characterization via atomic force microscopy indicates that the stretching deformation of the sundew adhesive is associated with the flexibility of its fibrous architectures. It is also observed that the adhesion strength of the sundew adhesive is susceptible to low temperatures. Both elasticity and adhesion strength of the sundew adhesive reduce in response to lowering the ambient temperature. The feasibility of applying sundew adhesive for tissue engineering is subsequently explored in this study. Results show that the fibrous scaffolds obtained from sundew adhesive are capable of increasing the adhesion of multiple types of cells, including fibroblast cells and smooth muscle cells, a property that results from the enhanced adsorption of serum proteins. In addition, in light of the weak cytotoxic activity exhibited by these scaffolds towards a variety of

  17. Adhesion enhancement of biomimetic dry adhesives by nanoparticle in situ synthesis

    NASA Astrophysics Data System (ADS)

    Díaz Téllez, J. P.; Harirchian-Saei, S.; Li, Y.; Menon, C.

    2013-10-01

    A novel method to increase the adhesion strength of a gecko-inspired dry adhesive is presented. Gold nanoparticles are synthesized on the tips of the microfibrils of a polymeric dry adhesive to increase its Hamaker constant. Formation of the gold nanoparticles is qualitatively studied through a colour change in the originally transparent substance and quantitatively analysed using ultraviolet-visible spectrophotometry. A pull-off force test is employed to quantify the adhesion enhancement. Specifically, adhesion forces of samples with and without embedded gold nanoparticles are measured and compared. The experimental results indicate that an adhesion improvement of 135% can be achieved.

  18. Osteoblast-derived WNT-induced secreted protein 1 increases VCAM-1 expression and enhances prostate cancer metastasis by down-regulating miR-126.

    PubMed

    Tai, Huai-Ching; Chang, An-Chen; Yu, Hong-Jeng; Huang, Chao-Yuan; Tsai, Yu-Chieh; Lai, Yu-Wei; Sun, Hui-Lung; Tang, Chih-Hsin; Wang, Shih-Wei

    2014-09-15

    Bone metastases of prostate cancer (PCa) may cause intractable pain. Wnt-1-induced secreted protein 1 (WISP-1) belongs to the CCN family (CTGF/CYR61/NOV) that plays a key role in bone formation. We found that osteoblast-conditioned medium (OBCM) stimulates migration and vascular adhesion molecule-1 (VCAM)-1 expression in human PCa (PC3 and DU145) cells. Osteoblast transfection with WISP-1 shRNA reduced OBCM-mediated PCa migration and VCAM-1 expression. Stimulation of PCa with OBCM or WISP-1 elevated focal adhesion kinase (FAK) and p38 phosphorylation. Either FAK and p38 inhibitors or siRNA abolished osteoblast-derived WISP-1-induced migration and VCAM-1 expression. Osteoblast-derived WISP-1 inhibited miR-126 expression. Moreover, miR-216 mimic reversed the WISP-1-enhanced migration and VCAM-1 expression. This study suggests that osteoblast-derived WISP-1 promotes migration and VCAM-1 expression in human PCa cells by down-regulating miR-126 expression via αvβ1 integrin, FAK, and p38 signaling pathways. Thus, WISP-1 may be a new molecular therapeutic target in PCa bone metastasis.

  19. Plasmodium falciparum Plasmodium helical interspersed subtelomeric proteins contribute to cytoadherence and anchor P. falciparum erythrocyte membrane protein 1 to the host cell cytoskeleton.

    PubMed

    Oberli, Alexander; Zurbrügg, Laura; Rusch, Sebastian; Brand, Françoise; Butler, Madeleine E; Day, Jemma L; Cutts, Erin E; Lavstsen, Thomas; Vakonakis, Ioannis; Beck, Hans-Peter

    2016-10-01

    Adherence of Plasmodium falciparum-infected erythrocytes to host endothelium is conferred through the parasite-derived virulence factor P. falciparum erythrocyte membrane protein 1 (PfEMP1), the major contributor to malaria severity. PfEMP1 located at knob structures on the erythrocyte surface is anchored to the cytoskeleton, and the Plasmodium helical interspersed subtelomeric (PHIST) gene family plays a role in many host cell modifications including binding the intracellular domain of PfEMP1. Here, we show that conditional reduction of the PHIST protein PFE1605w strongly reduces adhesion of infected erythrocytes to the endothelial receptor CD36. Adhesion to other endothelial receptors was less affected or even unaltered by PFE1605w depletion, suggesting that PHIST proteins might be optimized for subsets of PfEMP1 variants. PFE1605w does not play a role in PfEMP1 transport, but it directly interacts with both the intracellular segment of PfEMP1 and with cytoskeletal components. This is the first report of a PHIST protein interacting with key molecules of the cytoadherence complex and the host cytoskeleton, and this functional role seems to play an essential role in the pathology of P. falciparum.

  20. Monocyte tethering by P-selectin regulates monocyte chemotactic protein-1 and tumor necrosis factor-alpha secretion. Signal integration and NF-kappa B translocation.

    PubMed Central

    Weyrich, A S; McIntyre, T M; McEver, R P; Prescott, S M; Zimmerman, G A

    1995-01-01

    Adhesion molecules that tether circulating leukocytes to endothelial cells may also transduce or modulate outside-in signals for cellular activation, providing an initial regulatory point in the inflammatory response. Adhesion of human monocytes to P-selectin, the most rapidly expressed endothelial tethering factor, increased the secretion of monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-alpha) by the leukocytes when they were stimulated with platelet-activating factor. Increased cytokine secretion was specifically inhibited by G1, an anti-P-selectin mAb that prevents P-selectin from binding to its ligand (P-selectin glycoprotein ligand-1) on myeloid cells. Moreover, tethering by P-selectin specifically enhanced nuclear translocation of nuclear factor-kappa B (NF-kappa B), a transcription factor required for expression of MCP-1, TNF-alpha, and other immediate-early genes. These results demonstrate that P-selectin, through its ligands on monocytes, may locally regulate cytokine secretion in inflamed tissues. Images PMID:7537762

  1. Multiple Plasmodium falciparum Erythrocyte Membrane Protein 1 Variants per Genome Can Bind IgM via Its Fc Fragment Fcμ.

    PubMed

    Jeppesen, Anine; Ditlev, Sisse Bolm; Soroka, Vladyslav; Stevenson, Liz; Turner, Louise; Dzikowski, Ron; Hviid, Lars; Barfod, Lea

    2015-10-01

    The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) adhesive proteins expressed on the surfaces of infected erythrocytes (IEs) are of key importance in the pathogenesis of P. falciparum malaria. Several structurally and functionally defined PfEMP1 types have been associated with severe clinical manifestations, such as cerebral malaria in children and placental malaria in pregnant women. PfEMP1 that can bind the Fc part of IgM (Fcμ) characterizes one such type, although the functional significance of this IgM binding to PfEMP1 remains unclear. In this study, we report the identification and functional analysis of five IgM-binding PfEMP1 proteins encoded by P. falciparum NF54. In addition to the VAR2CSA-type PFL0030c protein, already known to bind Fcμ and to mediate chondroitin sulfate A (CSA)-specific adhesion of IEs in the placenta, we found four PfEMP1 proteins not previously known to bind IgM this way. Although they all contained Duffy binding-like ε (DBLε) domains similar to those in VAR2CSA-type PfEMP1, they did not mediate IE adhesion to CSA, and IgM binding did not shield IEs from phagocytosis of IgG-opsonized IEs. In this way, these new IgM-binding PfEMP1 proteins resemble the rosette-mediating and IgM-binding PfEMP1 HB3VAR06, but none of them mediated formation of rosettes. We could map the capacity for Fc-specific IgM binding to DBLε domains near the C terminus for three of the four PfEMP1 proteins tested. Our study provides new evidence regarding Fc-dependent binding of IgM to PfEMP1, which appears to be a common and multifunctional phenotype.

  2. Proteomic dataset of the sea urchin Paracentrotus lividus adhesive organs and secreted adhesive.

    PubMed

    Lebesgue, Nicolas; da Costa, Gonçalo; Ribeiro, Raquel Mesquita; Ribeiro-Silva, Cristina; Martins, Gabriel G; Matranga, Valeria; Scholten, Arjen; Cordeiro, Carlos; Heck, Albert J R; Santos, Romana

    2016-06-01

    Sea urchins have specialized adhesive organs called tube feet, which mediate strong but reversible adhesion. Tube feet are composed by a disc, producing adhesive and de-adhesive secretions for substratum attachment, and a stem for movement. After detachment the secreted adhesive remains bound to the substratum as a footprint. Recently, a label-free quantitative proteomic approach coupled with the latest mass-spectrometry technology was used to analyze the differential proteome of Paracentrotus lividus adhesive organ, comparing protein expression levels in the tube feet adhesive part (the disc) versus the non-adhesive part (the stem), and also to profile the proteome of the secreted adhesive (glue). This data article contains complementary figures and results related to the research article "Deciphering the molecular mechanisms underlying sea urchin reversible adhesion: a quantitative proteomics approach" (Lebesgue et al., 2016) [1]. Here we provide a dataset of 1384 non-redundant proteins, their fragmented peptides and expression levels, resultant from the analysis of the tube feet differential proteome. Of these, 163 highly over-expressed tube feet disc proteins (>3-fold), likely representing the most relevant proteins for sea urchin reversible adhesion, were further annotated in order to determine the potential functions. In addition, we provide a dataset of 611 non-redundant proteins identified in the secreted adhesive proteome, as well as their functional annotation and grouping in 5 major protein groups related with adhesive exocytosis, and microbial protection. This list was further analyzed to identify the most abundant protein groups and pinpoint putative adhesive proteins, such as Nectin, the most abundant adhesive protein in sea urchin glue. The obtained data uncover the key proteins involved in sea urchins reversible adhesion, representing a step forward to the development of new wet-effective bio-inspired adhesives.

  3. Proteomic dataset of the sea urchin Paracentrotus lividus adhesive organs and secreted adhesive.

    PubMed

    Lebesgue, Nicolas; da Costa, Gonçalo; Ribeiro, Raquel Mesquita; Ribeiro-Silva, Cristina; Martins, Gabriel G; Matranga, Valeria; Scholten, Arjen; Cordeiro, Carlos; Heck, Albert J R; Santos, Romana

    2016-06-01

    Sea urchins have specialized adhesive organs called tube feet, which mediate strong but reversible adhesion. Tube feet are composed by a disc, producing adhesive and de-adhesive secretions for substratum attachment, and a stem for movement. After detachment the secreted adhesive remains bound to the substratum as a footprint. Recently, a label-free quantitative proteomic approach coupled with the latest mass-spectrometry technology was used to analyze the differential proteome of Paracentrotus lividus adhesive organ, comparing protein expression levels in the tube feet adhesive part (the disc) versus the non-adhesive part (the stem), and also to profile the proteome of the secreted adhesive (glue). This data article contains complementary figures and results related to the research article "Deciphering the molecular mechanisms underlying sea urchin reversible adhesion: a quantitative proteomics approach" (Lebesgue et al., 2016) [1]. Here we provide a dataset of 1384 non-redundant proteins, their fragmented peptides and expression levels, resultant from the analysis of the tube feet differential proteome. Of these, 163 highly over-expressed tube feet disc proteins (>3-fold), likely representing the most relevant proteins for sea urchin reversible adhesion, were further annotated in order to determine the potential functions. In addition, we provide a dataset of 611 non-redundant proteins identified in the secreted adhesive proteome, as well as their functional annotation and grouping in 5 major protein groups related with adhesive exocytosis, and microbial protection. This list was further analyzed to identify the most abundant protein groups and pinpoint putative adhesive proteins, such as Nectin, the most abundant adhesive protein in sea urchin glue. The obtained data uncover the key proteins involved in sea urchins reversible adhesion, representing a step forward to the development of new wet-effective bio-inspired adhesives. PMID:27182547

  4. A batch fabricated biomimetic dry adhesive

    NASA Astrophysics Data System (ADS)

    Northen, Michael T.; Turner, Kimberly L.

    2005-08-01

    The fine hair adhesive system found in nature is capable of reversibly adhering to just about any surface. This dry adhesive, best demonstrated in the pad of the gecko, makes use of a multilevel conformal structure to greatly increase inelastic surface contact, enhancing short range interactions and producing significant amounts of attractive forces. Recent work has attempted to reproduce and test the terminal submicrometre 'hairs' of the system. Here we report the first batch fabricated multi-scale conformal system to mimic nature's dry adhesive. The approach makes use of massively parallel MEMS processing technology to produce 20-150 µm platforms, supported by single slender pillars, and coated with ~2 µm long, ~200 nm diameter, organic looking polymer nanorods, or 'organorods'. To characterize the structures a new mesoscale nanoindenter adhesion test technique has been developed. Experiments indicate significantly improved adhesion with the multiscale system. Additional processing caused a hydrophilic to hydrophobic transformation of the surface and testing indicated further improvement in adhesion.

  5. Control of vascular permeability by adhesion molecules

    PubMed Central

    Sarelius, Ingrid H; Glading, Angela J

    2014-01-01

    Vascular permeability is a vital function of the circulatory system that is regulated in large part by the limited flux of solutes, water, and cells through the endothelial cell layer. One major pathway through this barrier is via the inter-endothelial junction, which is driven by the regulation of cadherin-based adhesions. The endothelium also forms attachments with surrounding proteins and cells via 2 classes of adhesion molecules, the integrins and IgCAMs. Integrins and IgCAMs propagate activation of multiple downstream signals that potentially impact cadherin adhesion. Here we discuss the known contributions of integrin and IgCAM signaling to the regulation of cadherin adhesion stability, endothelial barrier function, and vascular permeability. Emphasis is placed on known and prospective crosstalk signaling mechanisms between integrins, the IgCAMs- ICAM-1 and PECAM-1, and inter-endothelial cadherin adhesions, as potential strategic signaling nodes for multipartite regulation of cadherin adhesion. PMID:25838987

  6. Functionally Graded Adhesives for Composite Joints

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott E.; Waas, Anthony M.; Arnold, Steven M.

    2012-01-01

    Adhesives with functionally graded material properties are being considered for use in adhesively bonded joints to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. An enhanced joint finite element, which uses an analytical formulation to obtain exact shape functions, is used to model the joint. Furthermore, proof of concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint.

  7. Adhesive curing through low-voltage activation

    NASA Astrophysics Data System (ADS)

    Ping, Jianfeng; Gao, Feng; Chen, Jian Lin; Webster, Richard D.; Steele, Terry W. J.

    2015-08-01

    Instant curing adhesives typically fall within three categories, being activated by either light (photocuring), heat (thermocuring) or chemical means. These curing strategies limit applications to specific substrates and can only be activated under certain conditions. Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine dendrimers and dissolving in aqueous solvents to form viscous gels. The electrocuring adhesives are activated at -2 V versus Ag/AgCl, allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage discontinued, crosslinking immediately terminated. Thus, crosslinking initiation and propagation are observed to be voltage and time dependent, enabling tuning of both material properties and adhesive strength. The electrocuring adhesive has immediate implications in manufacturing and development of implantable bioadhesives.

  8. Synaptic Cell Adhesion Molecules in Alzheimer's Disease

    PubMed Central

    Leshchyns'ka, Iryna

    2016-01-01

    Alzheimer's disease (AD) is a neurodegenerative brain disorder associated with the loss of synapses between neurons in the brain. Synaptic cell adhesion molecules are cell surface glycoproteins which are expressed at the synaptic plasma membranes of neurons. These proteins play key roles in formation and maintenance of synapses and regulation of synaptic plasticity. Genetic studies and biochemical analysis of the human brain tissue, cerebrospinal fluid, and sera from AD patients indicate that levels and function of synaptic cell adhesion molecules are affected in AD. Synaptic cell adhesion molecules interact with Aβ, a peptide accumulating in AD brains, which affects their expression and synaptic localization. Synaptic cell adhesion molecules also regulate the production of Aβ via interaction with the key enzymes involved in Aβ formation. Aβ-dependent changes in synaptic adhesion affect the function and integrity of synapses suggesting that alterations in synaptic adhesion play key roles in the disruption of neuronal networks in AD. PMID:27242933

  9. Adhesive curing through low-voltage activation

    PubMed Central

    Ping, Jianfeng; Gao, Feng; Chen, Jian Lin; Webster, Richard D.; Steele, Terry W. J.

    2015-01-01

    Instant curing adhesives typically fall within three categories, being activated by either light (photocuring), heat (thermocuring) or chemical means. These curing strategies limit applications to specific substrates and can only be activated under certain conditions. Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine dendrimers and dissolving in aqueous solvents to form viscous gels. The electrocuring adhesives are activated at −2 V versus Ag/AgCl, allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage discontinued, crosslinking immediately terminated. Thus, crosslinking initiation and propagation are observed to be voltage and time dependent, enabling tuning of both material properties and adhesive strength. The electrocuring adhesive has immediate implications in manufacturing and development of implantable bioadhesives. PMID:26282730

  10. Mussel-Inspired Adhesives and Coatings

    PubMed Central

    Lee, Bruce P.; Messersmith, P.B.; Israelachvili, J.N.; Waite, J.H.

    2011-01-01

    Mussels attach to solid surfaces in the sea. Their adhesion must be rapid, strong, and tough, or else they will be dislodged and dashed to pieces by the next incoming wave. Given the dearth of synthetic adhesives for wet polar surfaces, much effort has been directed to characterizing and mimicking essential features of the adhesive chemistry practiced by mussels. Studies of these organisms have uncovered important adaptive strategies that help to circumvent the high dielectric and solvation properties of water that typically frustrate adhesion. In a chemical vein, the adhesive proteins of mussels are heavily decorated with Dopa, a catecholic functionality. Various synthetic polymers have been functionalized with catechols to provide diverse adhesive, sealant, coating, and anchoring properties, particularly for critical biomedical applications. PMID:22058660

  11. NR-150B2 adhesive development

    NASA Technical Reports Server (NTRS)

    Blatz, P. S.

    1978-01-01

    Adhesive based polyimide solutions which are more easily processed than conventional aromatic polyimide systems and show potential for use for extended times at 589K are discussed. The adhesive system is based on a solution containing diglyme as the solvent and 2,2 bis(3',4'-dicarboxyphenyl)hexafluoropropane, paraphenylenediamine, and oxydianiline. The replacement of N-methylpyrrolidone with diglyme as the solvent was found to improve the adhesive strengths of lap shear samples and simplify the processing conditions for bonding both titanium and graphite fiber/polyimide matrix resin composites. Information was obtained on the effects of various environments including high humidity, immersion in jet fuel and methylethylketone on aluminum filled adhesive bonds. The adhesive was also evaluated in wide area bonds and flatwise tensile specimens using titanium honeycomb and composite face sheets. It was indicated that the developed adhesive system has the potential for use in applications requiring long term exposure to at least 589K (600 F).

  12. Control of vascular permeability by adhesion molecules.

    PubMed

    Sarelius, Ingrid H; Glading, Angela J

    2015-01-01

    Vascular permeability is a vital function of the circulatory system that is regulated in large part by the limited flux of solutes, water, and cells through the endothelial cell layer. One major pathway through this barrier is via the inter-endothelial junction, which is driven by the regulation of cadherin-based adhesions. The endothelium also forms attachments with surrounding proteins and cells via 2 classes of adhesion molecules, the integrins and IgCAMs. Integrins and IgCAMs propagate activation of multiple downstream signals that potentially impact cadherin adhesion. Here we discuss the known contributions of integrin and IgCAM signaling to the regulation of cadherin adhesion stability, endothelial barrier function, and vascular permeability. Emphasis is placed on known and prospective crosstalk signaling mechanisms between integrins, the IgCAMs- ICAM-1 and PECAM-1, and inter-endothelial cadherin adhesions, as potential strategic signaling nodes for multipartite regulation of cadherin adhesion. PMID:25838987

  13. Adhesion and wear resistance of materials

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1986-01-01

    Recent studies into the nature of bonding at the interface between two solids in contact or a solid and deposited film have provided a better understanding of those properties important to the adhesive wear resistance of materials. Analytical and experimental progress are reviewed. For simple metal systems the adhesive bond forces are related to electronic wave function overlap. With metals in contact with nonmetals, molecular-orbital energy, and density of states, respectively can provide insight into adhesion and wear. Experimental results are presented which correlate adhesive forces measured between solids and the electronic surface structures. Orientation, surface reconstruction, surface segregation, adsorption are all shown to influence adhesive interfacial strength. The interrelationship between adhesion and the wear of the various materials as well as the life of coatings applied to substrates are discussed. Metallic systems addressed include simple metals and alloys and these materials in contact with themselves, both oxide and nonoxide ceramics, diamond, polymers, and inorganic coating compounds, h as diamondlike carbon.

  14. Innate Non-Specific Cell Substratum Adhesion

    PubMed Central

    Loomis, William F.; Fuller, Danny; Gutierrez, Edgar; Groisman, Alex; Rappel, Wouter-Jan

    2012-01-01

    Adhesion of motile cells to solid surfaces is necessary to transmit forces required for propulsion. Unlike mammalian cells, Dictyostelium cells do not make integrin mediated focal adhesions. Nevertheless, they can move rapidly on both hydrophobic and hydrophilic surfaces. We have found that adhesion to such surfaces can be inhibited by addition of sugars or amino acids to the buffer. Treating whole cells with αlpha-mannosidase to cleave surface oligosaccharides also reduces adhesion. The results indicate that adhesion of these cells is mediated by van der Waals attraction of their surface glycoproteins to the underlying substratum. Since glycoproteins are prevalent components of the surface of most cells, innate adhesion may be a common cellular property that has been overlooked. PMID:22952588

  15. Bacterial Adhesion at Synthetic Surfaces

    PubMed Central

    Cunliffe, D.; Smart, C. A.; Alexander, C.; Vulfson, E. N.

    1999-01-01

    A systematic investigation into the effect of surface chemistry on bacterial adhesion was carried out. In particular, a number of physicochemical factors important in defining the surface at the molecular level were assessed for their effect on the adhesion of Listeria monocytogenes, Salmonella typhimurium, Staphylococcus aureus, and Escherichia coli. The primary experiments involved the grafting of groups varying in hydrophilicity, hydrophobicity, chain length, and chemical functionality onto glass substrates such that the surfaces were homogeneous and densely packed with functional groups. All of the surfaces were found to be chemically well defined, and their measured surface energies varied from 15 to 41 mJ · m−2. Protein adsorption experiments were performed with 3H-labelled bovine serum albumin and cytochrome c prior to bacterial attachment studies. Hydrophilic uncharged surfaces showed the greatest resistance to protein adsorption; however, our studies also showed that the effectiveness of poly(ethyleneoxide) (PEO) polymers was not simply a result of its hydrophilicity and molecular weight alone. The adsorption of the two proteins approximately correlated with short-term cell adhesion, and bacterial attachment for L. monocytogenes and E. coli also correlated with the chemistry of the underlying substrate. However, for S. aureus and S. typhimurium a different pattern of attachment occurred, suggesting a dissimilar mechanism of cell attachment, although high-molecular-weight PEO was still the least-cell-adsorbing surface. The implications of this for in vivo attachment of cells suggest that hydrophilic passivating groups may be the best method for preventing cell adsorption to synthetic substrates provided they can be grafted uniformly and in sufficient density at the surface. PMID:10543814

  16. Influence of Sodium Periodate and Tyrosinase on Binding of Alginate to Adlayers of Mytilus edulis Foot Protein 1.

    PubMed

    Suci; Geesey

    2000-10-15

    Mytilus edulis foot protein 1 (Mefp-1) is the most well-characterized component of this sea mussel's adhesive plaque. The plaque is a condensed, heterogeneous mixture consisting of a large proportion of cross-linked biopolymers that bonds the mussel to a chosen mooring. Mefp-1 is densely populated with lysine and L-3,4-dihyroxyphenylalanine (L-dopa) residues incorporated into a repeating amino acid sequence motif. It has been proposed that one plaque cross-linking reaction is the nucleophilic addition of the epsilon-amino groups of the lysine residues into the oxidized catechol (o-diphenol) functionality (quinone) of the L-dopa residues. In order to determine if this reaction occurs in adlayers of Mefp-1, a previously developed assay for epsilon-amino groups was applied. Adlayers of Mefp-1 were exposed to an oxidant, either the enzyme, mushroom tyrosinase, or sodium periodate. Binding of alginate to adlayers was used to probe for accessibility of epsilon-amino groups. It was found that lysine residues lose the ability to bind alginate after exposure to sodium periodate, but that this loss is not clearly due to a reaction with L-dopa residues. There is a slight decrease of binding of alginate to adlayers of Mefp-1 exposed to either active or thermally deactivated mushroom tyrosinase, probably due to the obstruction of binding sites by bound enzyme. Adsorption kinetics of mushroom tyrosinase onto adlayers of Mefp-1 for active and thermally inactivated enzyme were nearly identical. Attenuated total reflection Fourier transform infrared spectroscopy was used to characterize these interactions at a germanium (Ge) interface. Copyright 2000 Academic Press. PMID:11017742

  17. Applicator for cyanoacrylate tissue adhesive.

    PubMed

    Wessels, I F; McNeill, J I

    1989-03-01

    Cyanoacrylate tissue adhesive (CTA) is very useful for emergency treatment of corneal perforations. Lack of Food and Drug Administration approval as well as concerns about toxicity from the application of large amounts of glue, however, have limited its use. It is difficult to apply a sufficiently small amount of glue or to achieve a water tight seal using published techniques of glue application. We have found a commercially available micropipette (used in dental work) to be more effective than other methods of CTA application. With this apparatus, precise and accurate placement of minimal amounts of CTA at the slit lamp is consistently possible.

  18. Curcumin attenuates adhesion molecules and matrix metalloproteinase expression in hypercholesterolemic rabbits.

    PubMed

    Um, Min Young; Hwang, Kwang Hyun; Choi, Won Hee; Ahn, Jiyun; Jung, Chang Hwa; Ha, Tae Youl

    2014-10-01

    Curcumin, the yellow substance found in turmeric, possesses antioxidant, anti-inflammation, anticancer, and lipid-lowering properties. Because we hypothesized that curcumin could ameliorate the development of atherosclerosis, the present study focused on the effects and potential mechanisms of curcumin consumption on high-cholesterol diet-induced atherosclerosis in rabbits. During our study, New Zealand white rabbits were fed 1 of 3 experimental diets: a normal diet, a normal diet enriched with 1% cholesterol (HCD), or an HCD supplemented with 0.2% curcumin. At the end of 8 weeks, blood samples were collected to determine the levels of serum lipids, cytokines, and soluble adhesion molecule levels. Gene expression of adhesion molecules and matrix metalloproteinases (MMPs) in aortas were measured by quantitative real-time polymerase chain reaction and Western blot. Compared with the HCD group, rabbits fed an HCD supplemented with 0.2% curcumin had significantly less aortic lesion areas and neointima thickening. Curcumin reduced the levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol, and oxidized low-density lipoprotein cholesterol in serum by 30.7%, 41.3%, 30.4%, and 66.9% (all P < .05), respectively, but did not affect high-density lipoprotein cholesterol levels. In addition, curcumin attenuated HCD-induced CD36 expression, circulating inflammatory cytokines, and soluble adhesive molecule levels. Curcumin reduced the mRNA and protein expression of intracellular adhesion molecule-1, vascular cell adhesion molecule-1, P-selectin, and monocyte chemotactic protein-1, and it inhibited HCD-induced up-regulation of MMP-1, MMP-2, and MMP-9. Our results demonstrate that curcumin exerts an antiatherosclerotic effect, which is mediated by multiple mechanisms that include lowering serum lipids and oxidized low-density lipoprotein, thus modulating the proinflammatory cytokine levels and altering adhesion molecules and MMP gene expression. PMID

  19. Curcumin attenuates adhesion molecules and matrix metalloproteinase expression in hypercholesterolemic rabbits.

    PubMed

    Um, Min Young; Hwang, Kwang Hyun; Choi, Won Hee; Ahn, Jiyun; Jung, Chang Hwa; Ha, Tae Youl

    2014-10-01

    Curcumin, the yellow substance found in turmeric, possesses antioxidant, anti-inflammation, anticancer, and lipid-lowering properties. Because we hypothesized that curcumin could ameliorate the development of atherosclerosis, the present study focused on the effects and potential mechanisms of curcumin consumption on high-cholesterol diet-induced atherosclerosis in rabbits. During our study, New Zealand white rabbits were fed 1 of 3 experimental diets: a normal diet, a normal diet enriched with 1% cholesterol (HCD), or an HCD supplemented with 0.2% curcumin. At the end of 8 weeks, blood samples were collected to determine the levels of serum lipids, cytokines, and soluble adhesion molecule levels. Gene expression of adhesion molecules and matrix metalloproteinases (MMPs) in aortas were measured by quantitative real-time polymerase chain reaction and Western blot. Compared with the HCD group, rabbits fed an HCD supplemented with 0.2% curcumin had significantly less aortic lesion areas and neointima thickening. Curcumin reduced the levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol, and oxidized low-density lipoprotein cholesterol in serum by 30.7%, 41.3%, 30.4%, and 66.9% (all P < .05), respectively, but did not affect high-density lipoprotein cholesterol levels. In addition, curcumin attenuated HCD-induced CD36 expression, circulating inflammatory cytokines, and soluble adhesive molecule levels. Curcumin reduced the mRNA and protein expression of intracellular adhesion molecule-1, vascular cell adhesion molecule-1, P-selectin, and monocyte chemotactic protein-1, and it inhibited HCD-induced up-regulation of MMP-1, MMP-2, and MMP-9. Our results demonstrate that curcumin exerts an antiatherosclerotic effect, which is mediated by multiple mechanisms that include lowering serum lipids and oxidized low-density lipoprotein, thus modulating the proinflammatory cytokine levels and altering adhesion molecules and MMP gene expression.

  20. Influence of composition on the adhesive strength and initial viscosity of denture adhesives.

    PubMed

    Han, Jian-min; Hong, Guang; Hayashida, Kentaro; Maeda, Takeshi; Murata, Hiroshi; Sasaki, Keiichi

    2014-01-01

    To investigate the effect of composition on the initial viscosity and adhesive strength between denture adhesives and the denture base. Two types of water-soluble polymers (methoxy ethylene maleic anhydride copolymer [PVM-MA] and sodium carboxymethyl cellulose [CMC]) were used. Samples were divided into three groups. Group 1 contained only PVM-MA; Group 2 contained only CMC; and Group 3 contained PVM-MA and CMC. The initial viscosity and adhesive strength were measured. For Group 1, the initial viscosity increased significantly as PVM-MA content increased. The adhesive strength of Group 1 lasted longer than Group 2. The adhesive strength of Group 3 varied greatly. The ratio of CMC and PVM-MA has a significant effect on the initial viscosity and adhesive strength of denture adhesives. Our results suggest that it is possible to improve the durability of a denture adhesive by combining different water-soluble polymers.

  1. Denture Adhesives in Prosthodontics: An Overview

    PubMed Central

    Kumar, P Ranjith; Shajahan, P A; Mathew, Jyothis; Koruthu, Anil; Aravind, Prasad; Ahammed, M Fazeel

    2015-01-01

    The use of denture adhesives is common among denture wearers, and it is also prescribed by many dentists. Prescribing denture adhesives has been viewed by many prosthodontists as a means of compensating for any defects in the fabrication procedures. Denture adhesives add to the retention and thereby improve chewing ability, reduce any instability, provide comfort and eliminate the accumulation of food debris beneath the dentures. Consequently, they increase the patient’s sense of security and satisfaction. However, obtaining the advice of the dental practitioner prior to the use of adhesives is a must. PMID:26225115

  2. Nucleation and growth of cadherin adhesions

    SciTech Connect

    Lambert, Mireille; Thoumine, Olivier; Brevier, Julien; Choquet, Daniel; Riveline, Daniel; Mege, Rene-Marc

    2007-11-15

    Cell-cell contact formation relies on the recruitment of cadherin molecules and their anchoring to actin. However, the precise chronology of events from initial cadherin trans-interactions to adhesion strengthening is unclear, in part due to the lack of access to the distribution of cadherins within adhesion zones. Using N-cadherin expressing cells interacting with N-cadherin coated surfaces, we characterized the formation of cadherin adhesions at the ventral cell surface. TIRF and RIC microscopies revealed streak-like accumulations of cadherin along actin fibers. FRAP analysis indicated that engaged cadherins display a slow turnover at equilibrium, compatible with a continuous addition and removal of cadherin molecules within the adhesive contact. Association of cadherin cytoplasmic tail to actin as well as actin cables and myosin II activity are required for the formation and maintenance of cadherin adhesions. Using time lapse microscopy we deciphered how cadherin adhesions form and grow. As lamellipodia protrude, cadherin foci stochastically formed a few microns away from the cell margin. Neo-formed foci coalesced aligned and coalesced with preformed foci either by rearward sliding or gap filling to form cadherin adhesions. Foci experienced collapse at the rear of cadherin adhesions. Based on these results, we present a model for the nucleation, directional growth and shrinkage of cadherin adhesions.

  3. Investigation of package sealing using organic adhesives

    NASA Technical Reports Server (NTRS)

    Perkins, K. L.; Licari, J. J.

    1977-01-01

    A systematic study was performed to evaluate the suitability of adhesives for sealing hybrid packages. Selected adhesives were screened on the basis of their ability to seal gold-plated Kovar butterfly-type packages that retain their seal integrity after individual exposures to increasingly severe temperature-humidity environments. Tests were also run using thermal shock, temperature cycling, mechanical shock and temperature aging. The four best adhesives were determined and further tested in a 60 C/98% RH environment and continuously monitored in regard to moisture content. Results are given, however, none of the tested adhesives passed all the tests.

  4. Comparison of three work of adhesion measurements

    SciTech Connect

    Emerson, J.A.; O`Toole, E.; Zamora, D.; Poon, B.

    1998-02-01

    Practical work of adhesion measurements are being studied for several types of polymer/metal combinations in order to obtain a better understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. The primary question is whether studies of model systems can be extended to systems of technological interest. The authors report on their first attempts to obtain the work of adhesion between a PDMS polymer and stainless steel. The work of adhesion measurements were made using three techniques -- contact angle, adhesive fracture energy at low deformation rates and JKR. Previous work by Whitesides` group show a good correlation between JKR and contact angle measurements for PDMS. Their initial work focused on duplicating the PDMS measurements of Chaudury. In addition, in this paper the authors extend the work of adhesion measurement to third technique -- interfacial failure energy. The ability to determine the reversible work of adhesion for practical adhesive joints allows understanding of several issues that control adhesion: surface preparation, nature of the interphase region, and bond durability.

  5. Adhesion of biocompatible and biodegradable micropatterned surfaces.

    PubMed

    Kaiser, Jessica S; Kamperman, Marleen; de Souza, Emerson J; Schick, Bernhard; Arzt, Eduard

    2011-02-01

    We studied the effects of pillar dimensions and stiffness of biocompatible and biodegradable micropatterned surfaces on adhesion on different compliant substrates. The micropatterned adhesives were based on biocompatible polydimethylsiloxane (PDMS) and biodegradable poly(lactic-co-glycolic) acid (PLGA) polymer systems. Micropatterned and non-patterned compliant PDMS did not show significant differences in adhesion on compliant mice ear skin or on gelatin-glycerin model substrates. However, adhesion measurements for micropatterned stiff PLGA on compliant gelatin-glycerin model substrates showed significant enhancement in pull-off strengths compared to non-patterned controls.

  6. The development of aerospace polyimide adhesives

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; St.clair, T. L.

    1983-01-01

    Few materials are available which can be used as aerospace adhesives at temperatures in the range of 300 C. The Materials Division at NASA-Langley Research Center developed several high temperature polyimide adhesives to fulfill the stringent needs of current aerospace programs. These adhesives are the result of a decade of basic research studies on the structure property relationships of both linear and addition aromatic polyimides. The development of both in house and commercially available polyimides is reviewed with regards to their potential for use as aerospace adhesives.

  7. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Pressure-sensitive adhesives. 175.125 Section 175... Adhesives § 175.125 Pressure-sensitive adhesives. Pressure-sensitive adhesives may be safely used as the... prescribed conditions: (a) Pressure-sensitive adhesives prepared from one or a mixture of two or more of...

  8. Design and fabrication of polymer based dry adhesives inspired by the gecko adhesive system

    NASA Astrophysics Data System (ADS)

    Jin, Kejia

    There has been significant interest in developing dry adhesives mimicking the gecko adhesive system, which offers several advantages compared to conventional pressure sensitive adhesives. Specifically, gecko adhesive pads have anisotropic adhesion properties: the adhesive pads (spatulae) stick strongly when sheared in one direction but are non-adherent when sheared in the opposite direction. This anisotropy property is attributed to the complex topography of the array of fine tilted and curved columnar structures (setae) that bear the spatulae. In this thesis, easy, scalable methods, relying on conventional and unconventional techniques are presented to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provide anisotropic adhesion properties. In the first part of the study, the anisotropic adhesion and friction properties of samples with various tilt angles to test the validity of a nanoscale tape-peeling model of spatular function are measured. Consistent with the Peel Zone model, samples with lower tilt angles yielded larger adhesion forces. Contact mechanics of the synthetic array were highly anisotropic, consistent with the frictional adhesion model and gecko-like. Based on the original design, a new design of gecko-like dry adhesives was developed which showed superior tribological properties and furthermore showed anisotropic adhesive properties without the need for tilt in the structures. These adhesives can be used to reversibly suspend weights from vertical surfaces (e.g., walls) and, for the first time to our knowledge, horizontal surfaces (e.g., ceilings) by simultaneously and judiciously activating anisotropic friction and adhesion forces. Furthermore, adhesion properties between artificial gecko-inspired dry adhesives and rough substrates with varying roughness are studied. The results suggest that both adhesion and friction forces on a rough substrate depends significantly on the

  9. Molecular Adhesion between Cartilage Extracellular Matrix Macromolecules

    PubMed Central

    2015-01-01

    In this study, we investigated the molecular adhesion between the major constituents of cartilage extracellular matrix, namely, the highly negatively charged proteoglycan aggrecan and the type II/IX/XI fibrillar collagen network, in simulated physiological conditions. Colloidal force spectroscopy was applied to measure the maximum adhesion force and total adhesion energy between aggrecan end-attached spherical tips (end radius R ≈ 2.5 μm) and trypsin-treated cartilage disks with undamaged collagen networks. Studies were carried out in various aqueous solutions to reveal the physical factors that govern aggrecan–collagen adhesion. Increasing both ionic strength and [Ca2+] significantly increased adhesion, highlighting the importance of electrostatic repulsion and Ca2+-mediated ion bridging effects. In addition, we probed how partial enzymatic degradation of the collagen network, which simulates osteoarthritic conditions, affects the aggrecan–collagen interactions. Interestingly, we found a significant increase in aggrecan–collagen adhesion even when there were no detectable changes at the macro- or microscales. It is hypothesized that the aggrecan–collagen adhesion, together with aggrecan–aggrecan self-adhesion, works synergistically to determine the local molecular deformability and energy dissipation of the cartilage matrix, in turn, affecting its macroscopic tissue properties. PMID:24491174

  10. Shear adhesion strength of aligned electrospun nanofibers.

    PubMed

    Najem, Johnny F; Wong, Shing-Chung; Ji, Guang

    2014-09-01

    Inspiration from nature such as insects' foot hairs motivates scientists to fabricate nanoscale cylindrical solids that allow tens of millions of contact points per unit area with material substrates. In this paper, we present a simple yet robust method for fabricating directionally sensitive shear adhesive laminates. By using aligned electrospun nylon-6, we create dry adhesives, as a succession of our previous work on measuring adhesion energies between two single free-standing electrospun polymer fibers in cross-cylinder geometry, randomly oriented membranes and substrate, and peel forces between aligned fibers and substrate. The synthetic aligned cylindrical solids in this study are electrically insulating and show a maximal Mode II shear adhesion strength of 27 N/cm(2) on a glass slide. This measured value, for the purpose of comparison, is 270% of that reported from gecko feet. The Mode II shear adhesion strength, based on a commonly known "dead-weight" test, is 97-fold greater than the Mode I (normal) adhesion strength of the same. The data indicate a strong shear binding on and easy normal lifting off. Anisotropic adhesion (Mode II/Mode I) is pronounced. The size and surface boundary effects, crystallinity, and bending stiffness of fibers are used to understand these electrospun nanofibers, which vastly differ from otherwise known adhesive technologies. The anisotropic strength distribution is attributed to a decreasing fiber diameter and an optimized laminate thickness, which, in turn, influences the bending stiffness and solid-state "wettability" of points of contact between nanofibers and surface asperities.

  11. Adhesive loose packings of small dry particles

    NASA Astrophysics Data System (ADS)

    Liu, Wenwei; Li, Shuiqing; Baule, Adrian; Makse, Hernán A.

    We explore adhesive loose packings of dry small spherical particles of micrometer size using 3D discrete-element simulations with adhesive contact mechanics. A dimensionless adhesion parameter ($Ad$) successfully combines the effects of particle velocities, sizes and the work of adhesion, identifying a universal regime of adhesive packings for $Ad>1$. The structural properties of the packings in this regime are well described by an ensemble approach based on a coarse-grained volume function that includes correlations between bulk and contact spheres. Our theoretical and numerical results predict: (i) An equation of state for adhesive loose packings that appears as a continuation from the frictionless random close packing (RCP) point in the jamming phase diagram; (ii) The existence of a maximal loose packing point at the coordination number $Z=2$ and packing fraction $\\phi=1/2^{3}$. Our results highlight that adhesion leads to a universal packing regime at packing fractions much smaller than the random loose packing, which can be described within a statistical mechanical framework. We present a general phase diagram of jammed matter comprising frictionless, frictional, adhesive as well as non-spherical particles, providing a classification of packings in terms of their continuation from the spherical frictionless RCP.

  12. Polyurethane adhesive with improved high temperature properties

    NASA Technical Reports Server (NTRS)

    Stuckey, J. M.

    1977-01-01

    A polyurethane resin with paste activator, capable of providing useful bond strengths over the temperature range of -184 C to 149 C, is described. The adhesive system has a pot life of over one hour. Tensile shear strength ratings are given for various adhesive formulations.

  13. Image analysis of blood platelets adhesion.

    PubMed

    Krízová, P; Rysavá, J; Vanícková, M; Cieslar, P; Dyr, J E

    2003-01-01

    Adhesion of blood platelets is one of the major events in haemostatic and thrombotic processes. We studied adhesion of blood platelets on fibrinogen and fibrin dimer sorbed on solid support material (glass, polystyrene). Adhesion was carried on under static and dynamic conditions and measured as percentage of the surface covered with platelets. Within a range of platelet counts in normal and in thrombocytopenic blood we observed a very significant decrease in platelet adhesion on fibrin dimer with bounded active thrombin with decreasing platelet count. Our results show the imperative use of platelet poor blood preparations as control samples in experiments with thrombocytopenic blood. Experiments carried on adhesive surfaces sorbed on polystyrene showed lower relative inaccuracy than on glass. Markedly different behaviour of platelets adhered on the same adhesive surface, which differed only in support material (glass or polystyrene) suggest that adhesion and mainly spreading of platelets depends on physical quality of the surface. While on polystyrene there were no significant differences between fibrin dimer and fibrinogen, adhesion measured on glass support material markedly differed between fibrin dimer and fibrinogen. We compared two methods of thresholding in image analysis of adhered platelets. Results obtained by image analysis of spreaded platelets showed higher relative inaccuracy than results obtained by image analysis of platelets centres and aggregates.

  14. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  15. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  16. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  17. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  18. 21 CFR 878.4380 - Drape adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Drape adhesive. 878.4380 Section 878.4380 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4380 Drape adhesive. (a) Identification....

  19. Sticky fingers: Adhesive properties of human fingertips.

    PubMed

    Spinner, Marlene; Wiechert, Anke B; Gorb, Stanislav N

    2016-02-29

    Fingertip friction is a rather well studied subject. Although the phenomenon of finger stickiness is known as well, the pull-off force and the adhesive strength of human finger tips have never been previously quantified. For the first time, we provided here characterization of adhesive properties of human fingers under natural conditions. Human fingers can generate a maximum adhesive force of 15mN on a smooth surface of epoxy resin. A weak correlation of the adhesive force and the normal force was found on all test surfaces. Up to 300mN load, an increase of the normal force leads to an increase of the adhesive force. On rough surfaces, the adhesive strength is significantly reduced. Our data collected from untreated hands give also an impression of an enormous scattering of digital adhesion depending on a large set of inter-subject variability and time-dependent individual factors (skin texture, moisture level, perspiration). The wide inter- and intra-individual range of digital adhesion should be considered in developing of technical and medical products. PMID:26892897

  20. Adhesion rings surround invadopodia and promote maturation

    PubMed Central

    Branch, Kevin M.; Hoshino, Daisuke; Weaver, Alissa M.

    2012-01-01

    Summary Invasion and metastasis are aggressive cancer phenotypes that are highly related to the ability of cancer cells to degrade extracellular matrix (ECM). At the cellular level, specialized actin-rich structures called invadopodia mediate focal matrix degradation by serving as exocytic sites for ECM-degrading proteinases. Adhesion signaling is likely to be a critical regulatory input to invadopodia, but the mechanism and location of such adhesion signaling events are poorly understood. Here, we report that adhesion rings surround invadopodia shortly after formation and correlate strongly with invadopodium activity on a cell-by-cell basis. By contrast, there was little correlation of focal adhesion number or size with cellular invadopodium activity. Prevention of adhesion ring formation by inhibition of RGD-binding integrins or knockdown (KD) of integrin-linked kinase (ILK) reduced the number of ECM-degrading invadopodia and reduced recruitment of IQGAP to invadopodium actin puncta. Furthermore, live cell imaging revealed that the rate of extracellular MT1-MMP accumulation at invadopodia was greatly reduced in both integrin-inhibited and ILK-KD cells. Conversely, KD of MT1-MMP reduced invadopodium activity and dynamics but not the number of adhesion-ringed invadopodia. These results suggest a model in which adhesion rings are recruited to invadopodia shortly after formation and promote invadopodium maturation by enhancing proteinase secretion. Since adhesion rings are a defining characteristic of podosomes, similar structures formed by normal cells, our data also suggest further similarities between invadopodia and podosomes. PMID:23213464

  1. ISOLATION OF INTEGRIN-BASED ADHESION COMPLEXES

    PubMed Central

    Jones, Matthew C.; Humphries, Jonathan D.; Byron, Adam; Millon-Frémillon, Angelique; Robertson, Joseph; Paul, Nikki R.; Ng, Daniel H. J.; Askari, Janet A.; Humphries, Martin J.

    2015-01-01

    The integration of cells with their extracellular environment is facilitated by cell surface adhesion receptors, such as integrins, which play important roles in both normal development and the onset of pathologies. Engagement of integrins with their ligands in the extracellular matrix, or counter receptors on other cells, initiates the intracellular assembly of a wide variety of proteins into adhesion complexes such as focal contacts, focal adhesions and fibrillar adhesions. The proteins recruited to these complexes mediate bidirectional signalling across the plasma membrane and as such help to coordinate and / or modulate the multitude of physical or chemical signals to which the cell is subjected. The protocols in this unit describe two approaches for the isolation or enrichment of proteins contained within integrin-associated adhesion complexes together with their local plasma membrane / cytosolic environments from cells in culture. In the first protocol integrin-associated adhesion structures are affinity isolated using microbeads coated with extracellular ligands or antibodies. The second protocol describes the isolation of ventral membrane preparations that are enriched for adhesion complex structures. The protocols permit the determination of adhesion complex components by subsequent downstream analysis by Western blotting or mass spectrometry. PMID:25727331

  2. Tensile and shear strength of adhesives

    NASA Technical Reports Server (NTRS)

    Stibolt, Kenneth A.

    1990-01-01

    This experiment is conducted in a freshman-level course: Introduction to Engineering Materials. There are no prerequisites for the course although students should have some knowledge of basic algebra. The objectives are to tension and shear test adhesives and to determine the tensile and shear properties of adhesives. Details of equipment of procedure are given.

  3. The effects of plasticity in adhesive fracture

    NASA Technical Reports Server (NTRS)

    Chang, M. D.; Devries, K. L.; Williams, M. L.

    1973-01-01

    An energy-balance analysis is presented for adhesive failure in end loaded cantilever beams. The analysis includes the effects of input work, stored strain energy, dissipated plastic energy, and specific adhesive surface energy. Experimental results obtained with 6061-T6 aluminum are presented as evidence for the validity of the approach.-

  4. Adhesion mechanism of a gecko-inspired oblique structure with an adhesive tip for asymmetric detachment

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Yu; Takahashi, Kunio; Sato, Chiaki

    2015-12-01

    An adhesion model of an oblique structure with an adhesive tip is proposed by considering a limiting stress for adhesion to describe the detachment mechanism of gecko foot hairs. When a force is applied to the root of the oblique structure, normal and shear stresses are generated at contact and the adhesive tip is detached from the surface when reaching the limiting stress. An adhesion criterion that considers both the normal and shear stresses is introduced, and the asymmetric detachment of the oblique structure is theoretically investigated. In addition, oblique beam array structures are manufactured, and an inclination effect of the structure on the asymmetric detachment is experimentally verified.

  5. Low density lipoprotein receptor related protein 1 variant interacts with saturated fatty acids in Puerto Ricans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low density lipoprotein related receptor protein 1 (LRP1) is a multi-functional endocytic receptor that is highly expressed in adipocytes and the hypothalamus. Animal models and in vitro studies support a role for LRP1 in adipocyte metabolism and leptin signaling, but genetic polymorphisms have not ...

  6. A review of the occurrence of grain softness protein-1 genes in wheat (Triticum aestivum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain softness protein-1 (Gsp-1) is a small, 495-bp intronless gene found throughout the Triticeae tribe at the distal end of group 5 chromosomes. With the Puroindolines, it constitutes a key component of the Hardness locus. In the polyploid wheats, Triticum aestivum and T. turgidum, the gene is pr...

  7. Adhesion through single peptide aptamers

    PubMed Central

    Aubin-Tam, Marie-Eve; Appleyard, David C.; Ferrari, Enrico; Garbin, Valeria; Fadiran, Oluwatimilehin O.; Kunkel, Jacquelyn; Lang, Matthew J.

    2014-01-01

    Aptamer and antibody mediated adhesion is central to biological function and valuable in the engineering of “lab on a chip” devices. Single molecule force spectroscopy using optical tweezers enables direct non-equilibrium measurement of these non-covalent interactions for three peptide aptamers selected for glass, polystyrene, and carbon nanotubes. A comprehensive examination of the strong attachment between anti-fluorescein 4-4-20 and fluorescein was also carried out using the same assay. Bond lifetime, barrier width, and free energy of activation are extracted from unbinding histogram data using three single molecule pulling models. The evaluated aptamers appear to adhere stronger than the fluorescein antibody under no- and low-load conditions, yet weaker than antibodies at loads above ~25pN. Comparison to force spectroscopy data of other biological linkages shows the diversity of load dependent binding and provides insight into linkages used in biological processes and those designed for engineered systems. PMID:20795685

  8. Bioinspired design of a hierarchically structured adhesive.

    PubMed

    Arul, Edward Peter; Ghatak, Animangsu

    2009-01-01

    The mechanism by which many creatures such as geckos can run at ease on a vertical wall and yet remain strongly adhered has been linked to hierarchically patterned microstructures: flexible pads, hairs, and subsurface fluidic vessels at their feet. Despite many advances, how these features of different length scales and the associated physical phenomena couple to engender this "smart" adhesive is yet to be understood and mimicked. In this context, we have designed elastomeric films of poly(dimethylsiloxane) embedded with stacks of planar microchannels, curved and straight, and channels with microscopically patterned walls. We have altered also chemically the adhesive surface including that of the microchannel walls by creating dangling chains. During indentation experiments, deformation and self-adhesion of these structures enhance the effective area of adhesion with a consequent increase in adhesion hysteresis over orders of magnitude. In addition, suitable orientation of these buried channels allows the generation of load dependent hysteresis and its spatial modulation. PMID:19063623

  9. Adhesion of elastomeric impression materials to trays.

    PubMed

    Bindra, B; Heath, J R

    1997-01-01

    The tensile and shear adhesive bond strengths of two addition cured silicones (Provil and Express) and a polyether (Impregum) impression material to brass, poly(methylmethacrylate) and visible light-cured (VLC) tray resin were determined. Adhesive application significantly increased the bond strength; Provil and Express adhered most strongly to brass; whilst the Impregum-VLC combination produced the strongest bond. Indeed, VLC resin generated greater adhesion than acrylic resin. Exchanging the adhesives specified for each silicone material generally resulted in higher bond strengths. No correlation was established between speed of separation of the test surfaces and bond strength. For optimum clinical performance, the impression material (adhesive) tray material giving the highest bond strength should be utilized.

  10. Critical length scale controls adhesive wear mechanisms.

    PubMed

    Aghababaei, Ramin; Warner, Derek H; Molinari, Jean-Francois

    2016-01-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients. PMID:27264270

  11. Adhesion, friction and micromechanical properties of ceramics

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1988-01-01

    The adhesion, friction, and micromechanical properties of ceramics, both in monolithic and coating form, are reviewed. Ceramics are examined in contact with themselves, other harder materials, and metals. For the simplicity of discussion, the tribological properties of concern in the processes are separated into two parts. The first part discusses the pull-off force (adhesion) and the shear force required to break the interfacial junctions between contacting surfaces. The role of chemical bonding in adhesion and friction, and the effects of surface contaminant films and temperature on tribological response with respect to adhesion and friction are discussed. The second part deals with abrasion of ceramics. Elastic, plastic, and fracture behavior of ceramics in solid state contact is discussed. The scratch technique of determining the critical load needed to fracture interfacial adhesive bonds of ceramic deposited on substrates is also addressed.

  12. [Adhesive and hemagglutinating properties of lactobacilli].

    PubMed

    Brilis, V I; Brilene, T A; Lentsner, Kh P; Lentsner, A A

    1982-09-01

    The study of the adhesive and hemagglutinating properties of the strains of different Lactobacillus species isolated from the human digestive tract and sour milk products were carried out. 49 strains of 9 Lactobacillus species were studied; of these, 10 strains had been isolated from saliva, 11 strains from feces, 7 strains from milk and 5 strains from sour cream. 11 collection strains and 2 strains used in the production of lactobacterin served as controls. Adhesion was studied in vitro on human red blood cells used as a model. Red blood cells used in the experiments had been taken from 23 donors aged 25-52 years. Lactobacilli were found to have certain inter and intraspecific differences in their adhesiveness. The adhesiveness of the lactobacilli isolated from human feces was considerably greater than that of the strains isolated from sour milk products and of the collection strains. Only the strains of lactobacilli with low adhesiveness possessed pronounced hemagglutinating properties. PMID:7148229

  13. Coating to enhance metal-polymer adhesion

    SciTech Connect

    Parthasarathi, A.; Mahulikar, D.

    1996-12-31

    An ultra-thin electroplated coating has been developed to enhance adhesion of metals to polymers. The coating was developed for microelectronic packaging applications where it greatly improves adhesion of metal leadframes to plastic molding compounds. Recent tests show that the coating enhances adhesion of different metals to other types of adhesives as well and may thus have wider applicability. Results of adhesion tests with this coating, as well as its other characteristics such as corrosion resistance, are discussed. The coating is a very thin transparent electroplated coating containing zinc and chromium. It has been found to be effective on a variety of metal surfaces including copper alloys, Fe-Ni alloys, Al alloys, stainless steel, silver, nickel, Pd/Ni and Ni-Sn. Contact resistance measurements show that the coating has little or no effect on electrical resistivity.

  14. Fatigue behavior of adhesively bonded joints

    NASA Technical Reports Server (NTRS)

    Mall, S.

    1983-01-01

    The fatigue damage mechanism of composite to composite adhesively bonded joints was characterized. The mechanics of the possible modes of fatigue damage propagation in these joints when subjected to constant amplitude cyclic mechanical loading were investigated. The possible failure modes in composite bonded joints may be cyclic debonding (i.e., progressive separation of the adhesive), interlaminar damage (delamination), adherend fatigue or a combination of these. Two composite systems - graphite/epoxy adhesively bonded to graphite/epoxy and Kevlar 49/epoxy adhesively bonded to Kevlar 49/epoxy were investigated. Both composite systems consisted of quasi-isotropic lay-ups, i.e., 0 deg/-45 deg/+45 deg/90 degs. The two adhesives, employed in the study were (1) EC 3445 with cure temperature of 250 F for secondary bonding and (2) FM 300 with cure temperature of 350 F for co-cure bonding.

  15. Critical length scale controls adhesive wear mechanisms

    PubMed Central

    Aghababaei, Ramin; Warner, Derek H.; Molinari, Jean-Francois

    2016-01-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients. PMID:27264270

  16. Critical length scale controls adhesive wear mechanisms

    NASA Astrophysics Data System (ADS)

    Aghababaei, Ramin; Warner, Derek H.; Molinari, Jean-Francois

    2016-06-01

    The adhesive wear process remains one of the least understood areas of mechanics. While it has long been established that adhesive wear is a direct result of contacting surface asperities, an agreed upon understanding of how contacting asperities lead to wear debris particle has remained elusive. This has restricted adhesive wear prediction to empirical models with limited transferability. Here we show that discrepant observations and predictions of two distinct adhesive wear mechanisms can be reconciled into a unified framework. Using atomistic simulations with model interatomic potentials, we reveal a transition in the asperity wear mechanism when contact junctions fall below a critical length scale. A simple analytic model is formulated to predict the transition in both the simulation results and experiments. This new understanding may help expand use of computer modelling to explore adhesive wear processes and to advance physics-based wear laws without empirical coefficients.

  17. Genetics Home Reference: leukocyte adhesion deficiency type 1

    MedlinePlus

    ... adhesion deficiency type 1 leukocyte adhesion deficiency type 1 Enable Javascript to view the expand/collapse boxes. ... All Close All Description Leukocyte adhesion deficiency type 1 is a disorder that causes the immune system ...

  18. Peritoneal adhesions after laparoscopic gastrointestinal surgery

    PubMed Central

    Mais, Valerio

    2014-01-01

    Although laparoscopy has the potential to reduce peritoneal trauma and post-operative peritoneal adhesion formation, only one randomized controlled trial and a few comparative retrospective clinical studies have addressed this issue. Laparoscopy reduces de novo adhesion formation but has no efficacy in reducing adhesion reformation after adhesiolysis. Moreover, several studies have suggested that the reduction of de novo post-operative adhesions does not seem to have a significant clinical impact. Experimental data in animal models have suggested that CO2 pneumoperitoneum can cause acute peritoneal inflammation during laparoscopy depending on the insufflation pressure and the surgery duration. Broad peritoneal cavity protection by the insufflation of a low-temperature humidified gas mixture of CO2, N2O and O2 seems to represent the best approach for reducing peritoneal inflammation due to pneumoperitoneum. However, these experimental data have not had a significant impact on the modification of laparoscopic instrumentation. In contrast, surgeons should train themselves to perform laparoscopy quickly, and they should complete their learning curves before testing chemical anti-adhesive agents and anti-adhesion barriers. Chemical anti-adhesive agents have the potential to exert broad peritoneal cavity protection against adhesion formation, but when these agents are used alone, the concentrations needed to prevent adhesions are too high and could cause major post-operative side effects. Anti-adhesion barriers have been used mainly in open surgery, but some clinical data from laparoscopic surgeries are already available. Sprays, gels, and fluid barriers are easier to apply in laparoscopic surgery than solid barriers. Results have been encouraging with solid barriers, spray barriers, and gel barriers, but they have been ambiguous with fluid barriers. Moreover, when barriers have been used alone, the maximum protection against adhesion formation has been no greater than

  19. Adhesion beyond the interface: Molecular adaptations of the mussel byssus to the intertidal zone

    NASA Astrophysics Data System (ADS)

    MIller, Dusty Rose

    The California mussel, Mytilus californianus, adheres robustly in the high-energy and oxidizing intertidal zone with a fibrous holdfast called the byssus using 3,4-dihydroxyphenyl-L-alanine (Dopa)-containing adhesive mussel foot proteins (mfps). There are many supporting roles to mussel adhesion that are intimately linked and ultimately responsible for mussel byssus's durable and dynamic adhesion. This dissertation explores these supporting mechanisms, including delivery of materials underwater, iron binding, friction, and antioxidant activity. As the outermost covering of the byssus, the cuticle deserves particular attention for its supporting roles to adhesion including the high stiffness and extensibility of the M. californianus byssal cuticle, which make it one of the most energy tolerant materials known. The cuticle's matrix-granule composite structure contributes to its toughness by microcracking between its harder granules and softer matrix. We investigated delivery of cuticular material underwater, cohesion of cuticle proteins, and surface damage mitigation by cuticle protein-based coacervates. To investigate underwater material delivery, we made cuticle matrix mimics by coacervating a key cuticular protein, Mytilus californianus foot protein 1, mfp-1, with hyaluronic acid. These matrix mimics coacervated over a wide range of solution conditions, delivered concentrated material, settled on and coated surfaces underwater. Because the granules are composed of mfp-1 condensed with iron, we used the surface forces apparatus to investigate the effects of iron on the cohesion of mfp-1 from two different species of mussels and found that subtle sequence variations modulate cohesion. Using the coacervate matrix mimics and, modeling the granules as a hard surface (mica), we investigated the wear protection of coacervated mfp-1/HA to mica under frictional shear and found that preventing wear depends critically on the presence of Dopa groups. In addition to cuticle

  20. Adhesion of cells to polystyrene surfaces

    PubMed Central

    1983-01-01

    The surface treatment of polystyrene, which is required to make polystyrene suitable for cell adhesion and spreading, was investigated. Examination of surfaces treated with sulfuric acid or various oxidizing agents using (a) x-ray photoelectron and attenuated total reflection spectroscopy and (b) measurement of surface carboxyl-, hydroxyl-, and sulfur-containing groups by various radiochemical methods showed that sulfuric acid produces an insignificant number of sulfonic acid groups on polystyrene. This technique together with various oxidation techniques that render surfaces suitable for cell culture generated high surface densities of hydroxyl groups. The importance of surface hydroxyl groups for the adhesion of baby hamster kidney cells or leukocytes was demonstrated by the inhibition of adhesion when these groups were blocked: blocking of carboxyl groups did not inhibit adhesion and may raise the adhesion of a surface. These results applied to cell adhesion in the presence and absence of serum. The relative unimportance of fibronectin for the adhesion and spreading of baby hamster kidney cells to hydroxyl-rich surfaces was concluded when cells spread on such surfaces after protein synthesis was inhibited with cycloheximide, fibronectin was removed by trypsinization, and trypsin activity was stopped with leupeptin. PMID:6355120

  1. Tissue Mechanics and Adhesion during Embryo Development

    PubMed Central

    Shawky, Joseph H.; Davidson, Lance A.

    2014-01-01

    During development cells interact mechanically with their microenvironment through cell-cell and cell-matrix adhesions. Many proteins involved in these adhesions serve both mechanical and signaling roles. In this review we will focus on the mechanical roles of these proteins and their complexes in transmitting force or stress from cell to cell or from cell to the extracellular matrix. As forces operate against tissues they establish tissue architecture, extracellular matrix assembly, and pattern cell shapes. As tissues become more established, adhesions play a major role integrating cells with the mechanics of their local environment. Adhesions may serve as both a molecular-specific glue, holding defined populations of cells together, and as a lubricant, allowing tissues to slide past one another. We review the biophysical principles and experimental tools used to study adhesion so that we may aid efforts to understand how adhesions guide these movements and integrate their signaling functions with mechanical function. As we conclude we review efforts to develop predictive models of adhesion that can be used to interpret experiments and guide future efforts to control and direct the process of tissue self-assembly during development. PMID:25512299

  2. Adhesive switching of membranes: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Bruinsma, Robijn; Behrisch, Almuth; Sackmann, Erich

    2000-04-01

    We report on a study of a model bioadhesion system: giant vesicles in contact with a supported lipid bilayer. Embedded in both membranes are very low concentrations of homophilic recognition molecules (contact site A receptors) competing with higher concentrations of repeller molecules: polyethylene glycol (PEG) lipids. These repellers mimic the inhibiting effect of the cell glycocalyx on adhesion. The effective adhesive interaction between the two membranes is probed by interferometric analysis of thermal fluctuations. We find two competing states of adhesion: initial weak adhesion is followed by slower aggregation of the adhesion molecules into small, tightly bound clusters that coexist with the regions of weak adhesion. We interpret our results in terms of a double-well intermembrane potential, and we present a theoretical analysis of the intermembrane interaction in the presence of mobile repeller molecules at a fixed chemical potential that shows that the interaction potential indeed should have just such a double-well shape. At a fixed repeller concentration we recover a conventional purely repulsive potential. We discuss the implications of our findings in terms of a general amplification mechanism of the action of sparse adhesion molecules by a nonspecific double-well potential. We also discuss the important role of the Helfrich undulation force for the proposed scenario.

  3. Adhesion in ceramics and magnetic media

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1989-01-01

    When a ceramic is brought into contact with a metal or a polymeric material such as a magnetic medium, strong bonds form between the materials. For ceramic-to-metal contacts, adhesion and friction are strongly dependent on the ductility of the metals. Hardness of metals plays a much more important role in adhesion and friction than does the surface energy of metals. Adhesion, friction, surface energy, and hardness of a metal are all related to its Young's modulus and shear modulus, which have a marked dependence on the electron configuration of the metal. An increase in shear modulus results in a decrease in area of contact that is greater than the corresponding increase in surface energy (the fond energy) with shear modulus. Consequently, the adhesion and friction decrease with increasing shear modulus. For ceramics in contact with polymeric magnetic tapes, environment is extremely important. For example, a nitrogen environment reduces adhesion and friction when ferrite contacts polymeric tape, whereas a vacuum environment strengthens the ferrite-to-tape adhesion and increases friction. Adhesion and friction are strongly dependent on the particle loading of the tape. An increase in magnetic particle concentration increases the complex modulus of the tape, and a lower real area of contact and lower friction result.

  4. Double-Stranded RNA-Induced Activation of Activating Protein-1 Promoter Is Differentially Regulated by the Non-structural Protein 1 of Avian Influenza A Viruses

    PubMed Central

    Zohari, Siamak; Belák, Sándor; Berg, Mikael

    2012-01-01

    Abstract Non-structural protein 1 (NS1) of influenza A viruses is a multifunctional protein that antagonizes the host immune response by interfering with several host signaling pathways. Based on putative amino acid sequences, NS1 proteins are categorized into two gene pools, allele A and allele B. Here we identified that allele A NS1 proteins of H6N8 and H4N6 are able to inhibit double-stranded RNA (dsRNA)-induced activating protein-1 (AP-1) promoter in cultured cell lines (human A549 and mink lung cells). Allele B NS1 proteins from corresponding subtypes of influenza A viruses are weak in this inhibition, despite significant levels of expression of each NS1 protein in human A549 cells. Furthermore, the capability to inhibit AP-1 promoter was mapped in the effector domain, since RNA binding domain alone lost its ability to inhibit this promoter activation. Chimeric forms of NS1 protein, composed of either RNA binding domain of allele A or B and effector domain of allele A or B, showed comparable inhibition to that of their wild-type NS1 proteins, or to the effector domain of corresponding NS1 proteins. Both alleles A and B NS1 proteins of H6N8 and H4N6 were expressed to significant levels, and were localized predominantly in the nucleus of human A549 cells. These results underscore the importance of the effector domain in inhibiting AP-1 promoter activation, and the biological function of the effector domain in stabilizing the RNA binding domain. Further, we revealed the versatile nature of NS1 in inhibiting the AP-1 transcription factor, in a manner dependent on allele type. Comprehensive studies, focusing on the molecular mechanisms behind this differential inhibition, may facilitate exploration of the zoonotic and pathogenic potential of influenza A viruses. PMID:22239235

  5. PTPRT regulates the interaction of Syntaxin-binding protein 1 with Syntaxin 1 through dephosphorylation of specific tyrosine residue

    SciTech Connect

    Lim, So-Hee; Moon, Jeonghee; Lee, Myungkyu; Lee, Jae-Ran

    2013-09-13

    Highlights: •PTPRT is a brain-specific, expressed, protein tyrosine phosphatase. •PTPRT regulated the interaction of Syntaxin-binding protein 1 with Syntaxin 1. •PTPRT dephosphorylated the specific tyrosine residue of Syntaxin-binding protein 1. •Dephosphorylation of Syntaxin-binding protein 1 enhanced the interaction with Syntaxin 1. •PTPRT appears to regulate the fusion of synaptic vesicle through dephosphorylation. -- Abstract: PTPRT (protein tyrosine phosphatase receptor T), a brain-specific tyrosine phosphatase, has been found to regulate synaptic formation and development of hippocampal neurons, but its regulation mechanism is not yet fully understood. Here, Syntaxin-binding protein 1, a key component of synaptic vesicle fusion machinery, was identified as a possible interaction partner and an endogenous substrate of PTPRT. PTPRT interacted with Syntaxin-binding protein 1 in rat synaptosome, and co-localized with Syntaxin-binding protein 1 in cultured hippocampal neurons. PTPRT dephosphorylated tyrosine 145 located around the linker between domain 1 and 2 of Syntaxin-binding protein 1. Syntaxin-binding protein 1 directly binds to Syntaxin 1, a t-SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein, and plays a role as catalysts of SNARE complex formation. Syntaxin-binding protein 1 mutant mimicking non-phosphorylation (Y145F) enhanced the interaction with Syntaxin 1 compared to wild type, and therefore, dephosphorylation of Syntaxin-binding protein 1 appeared to be important for SNARE-complex formation. In conclusion, PTPRT could regulate the interaction of Syntaxin-binding protein 1 with Syntaxin 1, and as a result, the synaptic vesicle fusion appeared to be controlled through dephosphorylation of Syntaxin-binding protein 1.

  6. Improving controllable adhesion on both rough and smooth surfaces with a hybrid electrostatic/gecko-like adhesive

    PubMed Central

    Ruffatto, Donald; Parness, Aaron; Spenko, Matthew

    2014-01-01

    This paper describes a novel, controllable adhesive that combines the benefits of electrostatic adhesives with gecko-like directional dry adhesives. When working in combination, the two technologies create a positive feedback cycle whose adhesion, depending on the surface type, is often greater than the sum of its parts. The directional dry adhesive brings the electrostatic adhesive closer to the surface, increasing its effect. Similarly, the electrostatic adhesion helps engage more of the directional dry adhesive fibrillar structures, particularly on rough surfaces. This paper presents the new hybrid adhesive's manufacturing process and compares its performance to three other adhesive technologies manufactured using a similar process: reinforced PDMS, electrostatic and directional dry adhesion. Tests were performed on a set of ceramic tiles with varying roughness to quantify its effect on shear adhesive force. The relative effectiveness of the hybrid adhesive increases as the surface roughness is increased. Experimental data are also presented for different substrate materials to demonstrate the enhanced performance achieved with the hybrid adhesive. Results show that the hybrid adhesive provides up to 5.1× greater adhesion than the electrostatic adhesive or directional dry adhesive technologies alone. PMID:24451392

  7. Improving controllable adhesion on both rough and smooth surfaces with a hybrid electrostatic/gecko-like adhesive.

    PubMed

    Ruffatto, Donald; Parness, Aaron; Spenko, Matthew

    2014-04-01

    This paper describes a novel, controllable adhesive that combines the benefits of electrostatic adhesives with gecko-like directional dry adhesives. When working in combination, the two technologies create a positive feedback cycle whose adhesion, depending on the surface type, is often greater than the sum of its parts. The directional dry adhesive brings the electrostatic adhesive closer to the surface, increasing its effect. Similarly, the electrostatic adhesion helps engage more of the directional dry adhesive fibrillar structures, particularly on rough surfaces. This paper presents the new hybrid adhesive's manufacturing process and compares its performance to three other adhesive technologies manufactured using a similar process: reinforced PDMS, electrostatic and directional dry adhesion. Tests were performed on a set of ceramic tiles with varying roughness to quantify its effect on shear adhesive force. The relative effectiveness of the hybrid adhesive increases as the surface roughness is increased. Experimental data are also presented for different substrate materials to demonstrate the enhanced performance achieved with the hybrid adhesive. Results show that the hybrid adhesive provides up to 5.1× greater adhesion than the electrostatic adhesive or directional dry adhesive technologies alone.

  8. Hierarchical bioinspired adhesive surfaces-a review.

    PubMed

    Brodoceanu, D; Bauer, C T; Kroner, E; Arzt, E; Kraus, T

    2016-01-01

    The extraordinary adherence and climbing agility of geckos on rough surfaces has been attributed to the multiscale hierarchical structures on their feet. Hundreds of thousands of elastic hairs called setae, each of which split into several spatulae, create a large number of contact points that generate substantial adhesion through van der Waals interactions. The hierarchical architecture provides increased structural compliance on surfaces with roughness features ranging from micrometers to millimeters. We review synthetic adhesion surfaces that mimic the naturally occurring hierarchy with an emphasis on microfabrication strategies, material choice and the adhesive performance achieved. PMID:27529743

  9. Molecular Architecture and Function of Matrix Adhesions

    PubMed Central

    Geiger, Benjamin; Yamada, Kenneth M.

    2011-01-01

    Cell adhesions mediate important bidirectional interactions between cells and the extracellular matrix. They provide an interactive interface between the extracellular chemical and physical environment and the cellular scaffolding and signaling machinery. This dynamic, reciprocal regulation of intracellular processes and the matrix is mediated by membrane receptors such as the integrins, as well as many other components that comprise the adhesome. Adhesome constituents assemble themselves into different types of cell adhesion structures that vary in molecular complexity and change over time. These cell adhesions play crucial roles in cell migration, proliferation, and determination of cell fate. PMID:21441590

  10. Method of making thermally removable adhesives

    DOEpatents

    Aubert, James H.

    2004-11-30

    A method of making a thermally-removable adhesive is provided where a bismaleimide compound, a monomeric furan compound, containing an oxirane group an amine curative are mixed together at an elevated temperature of greater than approximately 90.degree. C. to form a homogeneous solution, which, when cooled to less than approximately 70.degree. C., simultaneously initiates a Diels-Alder reaction between the furan and the bismaleimide and a epoxy curing reaction between the amine curative and the oxirane group to form a thermally-removable adhesive. Subsequent heating to a temperature greater than approximately 100.degree. C. causes the adhesive to melt and allows separation of adhered pieces.

  11. Weld bonding of titanium with polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Sheppard, C. H.; Orell, M. K.

    1975-01-01

    A conductive adhesive primer and a capillary flow adhesive were developed for weld bonding titanium alloy joints. Both formulations contained ingredients considered to be non-carcinogenic. Lap-shear joint test specimens and stringer-stiffened panels were weld bonded using a capillary flow process to apply the adhesive. Static property information was generated for weld bonded joints over the temperature range of 219K (-65 F) to 561K (550 F). The capillary flow process was demonstrated to produce weld bonded joints of equal strength to the weld through weld bonding process developed previously.

  12. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, Robert J.; McMillan, April D.; Paulauskas, Felix L.; Fathi, Zakaryae; Wei, Jianghua

    1998-01-01

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy.

  13. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

    1998-09-08

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

  14. Adhesive bonding using variable frequency microwave energy

    DOEpatents

    Lauf, R.J.; McMillan, A.D.; Paulauskas, F.L.; Fathi, Z.; Wei, J.

    1998-08-25

    Methods of facilitating the adhesive bonding of various components with variable frequency microwave energy are disclosed. The time required to cure a polymeric adhesive is decreased by placing components to be bonded via the adhesive in a microwave heating apparatus having a multimode cavity and irradiated with microwaves of varying frequencies. Methods of uniformly heating various articles having conductive fibers disposed therein are provided. Microwave energy may be selectively oriented to enter an edge portion of an article having conductive fibers therein. An edge portion of an article having conductive fibers therein may be selectively shielded from microwave energy. 26 figs.

  15. Adhesives and emollients in the preterm infant.

    PubMed

    Hoath, S B; Narendran, V

    2000-11-01

    This chapter focuses on recent advances in preterm infant skin care related to skin adhesion and skin emolliency. Different types of adhesives and hydrating agents are reviewed. Clinical applications are best guided by understanding the biology of epidermal barrier development. The role of xeric stress in accelerating formation of the stratum corneum is discussed along with the effects of occlusive agents and emollients on wound healing and epidermal barrier repair. The principles of skin moisturization are introduced. The concept is advanced that programmatic changes in skin adhesion and water handling occur during the normal ontogeny of superficial biofilms (sebum, sweat, acid mantle).

  16. The development of low temperature curing adhesives

    NASA Technical Reports Server (NTRS)

    Green, H. E.; Sutherland, J. D.; Hom, J. M.; Sheppard, C. H.

    1975-01-01

    An approach for the development of a practical low temperature (293 K-311 K/68 F-100 F) curing adhesive system based on a family of amide/ester resins was studied and demonstrated. The work was conducted on resin optimization and adhesive compounding studies. An improved preparative method was demonstrated which involved the reaction of an amine-alcohol precursor, in a DMF solution with acid chloride. Experimental studies indicated that an adhesive formulation containing aluminum powder provided the best performance when used in conjunction with a commercial primer.

  17. Stress-Inducible Protein 1 (STI1): Extracellular Vesicle Analysis and Quantification.

    PubMed

    Dias, Marcos Vinicios Salles; Martins, Vilma Regina; Hajj, Glaucia Noeli Maroso

    2016-01-01

    This chapter is derived from our experience in the study of stress-Inducible Protein 1 (STI1) in extracellular vesicles. We used different techniques to isolate, explore, and characterize the extracellular vesicles that contained this protein. Ultracentrifugation and gel chromatography were used to isolate extracellular vesicles of different sizes, nanotracking particle analysis (NTA) determined number and size of vesicles, while flow cytometry and ELISA were used to determine the specific protein content of vesicles. PMID:27665558

  18. Dickkopf-Related Protein 1 Inhibits the WNT Signaling Pathway and Improves Pig Oocyte Maturation

    PubMed Central

    Spate, Lee D.; Brown, Alana N.; Redel, Bethany K.; Whitworth, Kristin M.; Murphy, Clifton N.; Prather, Randall S.

    2014-01-01

    The ability to mature oocytes in vitro provides a tool for creating embryos by parthenogenesis, fertilization, and cloning. Unfortunately the quality of oocytes matured in vitro falls behind that of in vivo matured oocytes. To address this difference, transcriptional profiling by deep sequencing was conducted on pig oocytes that were either matured in vitro or in vivo. Alignment of over 18 million reads identified 1,316 transcripts that were differentially represented. One pathway that was overrepresented in the oocytes matured in vitro was for Wingless-type MMTV integration site (WNT) signaling. In an attempt to inhibit the WNT pathway, Dickkopf-related protein 1 was added to the in vitro maturation medium. Addition of Dickkopf-related protein 1 improved the percentage of oocytes that matured to the metaphase II stage, increased the number of nuclei in the resulting blastocyst stage embryos, and reduced the amount of disheveled segment polarity protein 1 protein in oocytes. It is concluded that transcriptional profiling is a powerful method for detecting differences between in vitro and in vivo matured oocytes, and that the WNT signaling pathway is important for proper oocyte maturation. PMID:24739947

  19. Porcine dentin matrix protein 1: gene structure, cDNA sequence, and expression in teeth.

    PubMed

    Kim, Jung-Wook; Yamakoshi, Yasuo; Iwata, Takanori; Hu, Yuan Yuan; Zhang, Hengmin; Hu, Jan C-C; Simmer, James P

    2006-02-01

    Dentin matrix protein 1 (DMP1) is an acidic non-collagenous protein that is necessary for the proper biomineralization of bone, cartilage, cementum, dentin, and enamel. Dentin matrix protein 1 is highly phosphorylated and potentially glycosylated, but there is no experimental data identifying which specific amino acids are modified. For the purpose of facilitating the characterization of DMP1 from pig, which has the advantage of large developing teeth for obtaining protein in quantity and extensive structural information concerning other tooth matrix proteins, we characterized the porcine DMP1 cDNA and gene structure, raised anti-peptide immunoglobulins that are specific for porcine DMP1, and detected DMP1 protein in porcine tooth extracts and histological sections. Porcine DMP1 has 510 amino acids, including a 16-amino acid signal peptide. The deduced molecular weight of the secreted, unmodified protein is 53.5 kDa. The protein has 93 serines and 12 threonines in the appropriate context for phosphorylation, and four asparagines in a context suitable for glycosylation. Dentin matrix protein 1 protein bands with apparent molecular weights between 30 and 45 kDa were observed in partially purified dentin extracts. In developing teeth, immunohistochemistry localized DMP1 in odontoblasts and the dentinal tubules of mineralized dentin and in ameloblasts, but not in the enamel matrix.

  20. Microtubules regulate focal adhesion dynamics through MAP4K4.

    PubMed

    Yue, Jiping; Xie, Min; Gou, Xuewen; Lee, Philbert; Schneider, Michael D; Wu, Xiaoyang

    2014-12-01

    Disassembly of focal adhesions (FAs) allows cell retraction and integrin detachment from the extracellular matrix, processes critical for cell movement. Growth of microtubules (MTs) can promote FA turnover by serving as tracks to deliver proteins essential for FA disassembly. The molecular nature of this FA "disassembly factor," however, remains elusive. By quantitative proteomics, we identified mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) as an FA regulator that associates with MTs. Knockout of MAP4K4 stabilizes FAs and impairs cell migration. By exploring underlying mechanisms, we further show that MAP4K4 associates with ending binding 2 (EB2) and IQ motif and SEC7 domain-containing protein 1 (IQSEC1), a guanine nucleotide exchange factor specific for Arf6, whose activation promotes integrin internalization. Together, our findings provide critical insight into FA disassembly, suggesting that MTs can deliver MAP4K4 toward FAs through EB2, where MAP4K4 can, in turn, activate Arf6 via IQSEC1 and enhance FA dissolution. PMID:25490267

  1. Evaluation of the adhesion of fiber posts cemented using different adhesive approaches.

    PubMed

    Radovic, Ivana; Mazzitelli, Claudia; Chieffi, Nicoletta; Ferrari, Marco

    2008-12-01

    The aim of this study was to investigate the adhesion of fiber posts cemented with luting agents that utilize three currently available adhesive approaches: etch-and-rinse, self-etch, and self-adhesive. Forty-two intact single-rooted human premolars were used in the study. Teeth were divided into six groups. In each group, a different resin cement with its adhesive system (if needed) and a fiber post were used. The groups were classified, according to the adhesive approach, into the following three categories. (i) Etch-and-rinse groups: Calibra resin cement/XPBond adhesive + self-curing activator (SCA)/RadiX Fiber Post (Dentsply Caulk), FluoroCore 2 core build-up material/XPBond + SCA/RadiX Fiber Post (Dentsply Caulk), and MultiCore Flow luting and core build-up material/Excite DSC adhesive/FRC Postec Plus fiber post (Ivoclar Vivadent). (ii) Self-etch group: Panavia F 2.0/ED primer (Kuraray)/RadiX Fiber Post (Dentsply Caulk). (iii) Self-adhesive groups: experimental self-adhesive cement/RadiX Fiber Post (Dentsply Caulk), and RelyX Unicem/RelyX Fiber Post (3M ESPE). The adhesion between the post and the root canal walls was assessed using the 'thin-slice' push-out test. In the test arrangement used, the self-etching approach may offer less favourable adhesion to root canal dentin in comparison with etch-and-rinse and self-adhesive approaches.

  2. Heat-shrinkable film improves adhesive bonds

    NASA Technical Reports Server (NTRS)

    Johns, J. M.; Reed, M. W.

    1980-01-01

    Pressure is applied during adhesive bonding by wrapping parts in heat-shrinkable plastic film. Film eliminates need to vacuum bag or heat parts in expensive autoclave. With procedure, operators are trained quickly, and no special skills are required.

  3. Chemistry technology: Adhesives and plastics: A compilation

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Technical information on chemical formulations for improving and/or producing adhesives is presented. Data are also reported on polymeric plastics with special characteristics or those plastics that were produced by innovative means.

  4. Recent Advances in Nanostructured Biomimetic Dry Adhesives

    PubMed Central

    Pattantyus-Abraham, Andras; Krahn, Jeffrey; Menon, Carlo

    2013-01-01

    The relatively large size of the gecko and its ability to climb a multitude of structures with ease has often been cited as the inspiration upon which the field of dry adhesives is based. Since 2010, there have been many advances in the field of dry adhesives with much of the new research focusing on developing nanoscale and hierarchical features in a concentrated effort to develop synthetic gecko-like dry adhesives which are strong, durable, and self-cleaning. A brief overview of the geckos and the hairs which it uses to adhere to many different surfaces is provided before delving into the current methods and materials used to fabricate synthetic gecko hairs. A summary of the recently published literature on bio-inspired, nanostructured dry adhesives is presented with an emphasis being placed on fabrication techniques. PMID:25023409

  5. Diverse evolutionary paths to cell adhesion.

    PubMed

    Abedin, Monika; King, Nicole

    2010-12-01

    The morphological diversity of animals, fungi, plants, and other multicellular organisms stems from the fact that each lineage acquired multicellularity independently. A prerequisite for each origin of multicellularity was the evolution of mechanisms for stable cell-cell adhesion or attachment. Recent advances in comparative genomics and phylogenetics provide critical insights into the evolutionary foundations of cell adhesion. Reconstructing the evolution of cell junction proteins in animals and their unicellular relatives exemplifies the roles of co-option and innovation. Comparative studies of volvocine algae reveal specific molecular changes that accompanied the evolution of multicellularity in Volvox. Comparisons between animals and Dictyostelium show how commonalities and differences in the biology of unicellular ancestors influenced the evolution of adhesive mechanisms. Understanding the unicellular ancestry of cell adhesion helps illuminate the basic cell biology of multicellular development in modern organisms. PMID:20817460

  6. Ins and Outs of Microbial Adhesion

    NASA Astrophysics Data System (ADS)

    Virji, Mumtaz

    Microbial adhesion is generally a complex process, involving multiple adhesins on a single microbe and their respective target receptors on host cells. In some situations, various adhesins of a microbe may co-operate in an apparently hierarchical and sequential manner whereby the first adhesive event triggers the target cell to express receptors for additional microbial adhesins. In other instances, adhesins may act in concert leading to high avidity interactions, often a prelude to cellular invasion and tissue penetration. Mechanisms used to target the host include both lectin-like interactions and protein-protein interactions; the latter are often highly specific for the host or a tissue within the host. This reflective chapter aims to offer a point of view on microbial adhesion by presenting some experiences and thoughts especially related to respiratory pathogens and explore if there can be any future hope of controlling bacterial infections via preventing adhesion or invasion stages of microbial pathogenesis.

  7. Advances in the Pathogenesis of Adhesion Development

    PubMed Central

    Awonuga, Awoniyi O.; Belotte, Jimmy; Abuanzeh, Suleiman; Fletcher, Nicole M.; Diamond, Michael P.

    2014-01-01

    Over the past several years, there has been increasing recognition that pathogenesis of adhesion development includes significant contributions of hypoxia induced at the site of surgery, the resulting oxidative stress, and the subsequent free radical production. Mitochondrial dysfunction generated by surgically induced tissue hypoxia and inflammation can lead to the production of reactive oxygen and nitrogen species as well as antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase which when optimal have the potential to abrogate mitochondrial dysfunction and oxidative stress, preventing the cascade of events leading to the development of adhesions in injured peritoneum. There is a significant cross talk between the several processes leading to whether or not adhesions would eventually develop. Several of these processes present avenues for the development of measures that can help in abrogating adhesion formation or reformation after intraabdominal surgery. PMID:24520085

  8. Ice adhesions in relation to freeze stress.

    PubMed

    Olien, C R; Smith, M N

    1977-10-01

    In freezing, competitive interaction between ice and hydrophilic plant substances causes an energy of adhesion to develop through the interstitial liquid. The thermodynamic basis for the adhesion energy is discussed, with estimates of the energies involved. In this research, effects of adhesion energy were observed microscopically in conjunction with energies of crystallization and frost desiccation. The complex character of ice in intact crown tissue of winter barley (Hordeum vulgare L.) and the problems of sectioning frozen tissue without producing artifacts led to an alternative study of single barley cells in a mesh of ice and cell wall polymers. Adhesions between ice, cell wall polymers, and the plasmalemma form a complexly interacting system in which the pattern of crystallization is a major factor in determination of stress and injury. PMID:16660124

  9. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4010 Tissue adhesive. (a) Tissue... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  10. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4010 Tissue adhesive. (a) Tissue... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  11. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4010 Tissue adhesive. (a) Tissue... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  12. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4010 Tissue adhesive. (a) Tissue... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  13. 21 CFR 878.4010 - Tissue adhesive.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4010 Tissue adhesive. (a) Tissue... intended for use in the embolization of brain arteriovenous malformation or for use in ophthalmic...

  14. Thread-Pull Test Of Curing Adhesive

    NASA Technical Reports Server (NTRS)

    Johnson, James A.

    1992-01-01

    Hardness (and degree of cure) of adhesive layer measured by pulling previously inserted thread out of layer. Strength of bond measured directly on assembly rather than on samples, which can be misleading.

  15. [Fiber-reinforced adhesive partial dentures].

    PubMed

    Kreulen, C M

    2003-06-01

    Dental applications of fiber-reinforced polymers include adhesive partial dentures. Dental resin composite materials can be reinforced by several types of fibres. Fiber orientation, proper wetting of the fibers by the resin and fiber volume are important. An application of fiber reinforced composites is the composite inlay bridge. This paper deals with some aspects of this type of adhesive partial denture. Advantages include the satisfactory esthetics and the minimally invasive character. Not clear yet is the long-term survival. The adhesive properties of fiber-reinforced adhesive partial dentures require an adaptation of the current dental philosophy, in which direct and indirect restorative techniques can be combined. An increase in knowledge and experience is needed to determine the dental applications. PMID:12852063

  16. Molecular dynamics simulation of interfacial adhesion

    SciTech Connect

    Yarovsky, I.; Chaffee, A.L.

    1996-12-31

    Chromium salts are often used in the pretreatment stages of steel painting processes in order to improve adhesion at the metal oxide/primer interface. Although well established empirically, the chemical basis for the improved adhesion conferred by chromia is not well understood. A molecular level understanding of this behaviour should provide a foundation for the design of materials offering improved adhesion control. Molecular modelling of adhesion involves simulation and analysis of molecular behaviour at the interface between two interacting phases. The present study concerns behaviour at the boundary between the metal coated steel surface (with or without chromium pretreatment) and an organic primer based on a solid epoxide resin produced from bisphenol A and epichlorohydrin. An epoxy resin oligomer of molecular weight 3750 was used as the model for the primer.

  17. Adhesion in hydrogels and model glassy polymers

    NASA Astrophysics Data System (ADS)

    Guvendiren, Murat

    Two main topics are addressed in this dissertation: (1) adhesion in hydrogels; (2) interfacial interactions between model glassy polymers. A self-assembly technique for the formation of hydrogels from acrylic triblock copolymer solutions was developed, based on vapor phase solvent exchange. Structure formation in the gels was characterized by small angle X-ray scattering, and swelling was measured in controlled pH buffer solutions. Strong gels are formed with polymer weight fractions between 0.01 and 0.15, and with shear moduli between 0.6 kPa and 3.5 kPa. Adhesive functionality, based on 3,4-dihydroxy-L-phenylalanine (DOPA) was also incorporated into the triblock copolymers. The effect of DOPA concentration on gel formation and swelling was investigated in detail. The adhesive properties of DOPA-functionalized hydrogels on TiO2 were investigated with an axisymmetric adhesion method. It was shown that the presence of DOPA enhances the adhesive properties of the hydrogels, but that the effect is minimized at pH values below 10, where the DOPA groups are hydrophobic. Thin film membranes were produced in order to study the specific interactions between DOPA and TiO2 and DOPA and tissue, using a membrane inflation method. The presence of DOPA in the membranes enhances the adhesion on TiO 2 and tissue, although adhesion to tissue requires that the DOPA groups be oxidized while in contact with the tissue of interest. Porous hydrogel scaffolds for tissue engineering applications were formed by adding salt crystals to the triblock copolymer solution prior to solvent exchange. Salt was then leached out by immersing the gel into water. Structures of the porous hydrogels were characterized by confocal laser scanning microscopy. These hydrogels were shown to be suitable for tissue regeneration and drug delivery applications. Diffusion-mediated adhesion between two component miscible polymer systems having very different glassy temperatures was also investigated. Axisymmetric

  18. Intercellular adhesion molecule-1 in the heart.

    PubMed

    Niessen, Hans W M; Krijnen, Paul A J; Visser, Cees A; Meijer, Chris J L M; Hack, C Erik

    2002-11-01

    Intercellular adhesion molecule-1 (ICAM-1) belongs to the superfamily of immunoglobulin-like adhesion molecules. Up-regulation of ICAM-1 occurs in many different pathophysiological processes. Also, cardiomyocytes can express ICAM-1-for example, in acute myocardial infarction. Moreover, inhibition of ICAM-1 expression in the heart dramatically reduces infarct size. Hence, inhibitors of ICAM-1 may provide a novel therapeutic option for acute myocardial infarction.

  19. Strengthening of dental adhesives via particle reinforcement.

    PubMed

    Belli, Renan; Kreppel, Stefan; Petschelt, Anselm; Hornberger, Helga; Boccaccini, Aldo R; Lohbauer, Ulrich

    2014-09-01

    The bond between methacrylic polymer adhesives and dental restoratives is not perfect and may fail either in the short or in the long term. This study aims to evaluate the effects of particle incorporation in a self-etch model adhesive on mechanical and physical properties that are relevant during application and service. Filled adhesives containing 5, 10, 15 or 25wt% glass fillers were compared to their unfilled counterpart in terms of water sorption and solubility; viscosity and dynamic viscosity during polymerization were recorded using rheological measurements and compared to FTIR analysis of the real-time degree of cure. Elastic modulus and ultimate tensile strength measurements were performed in uniaxial tension; the energy to fracture was used to calculate the fracture toughness of the adhesives. Finally, the experimental adhesives were applied on dentin substrate to test the bond strength using the microtensile test. Results showed that the incorporation of 5-10wt% nanofiller to self-etching dental adhesives is efficient in accelerating the polymerization reaction and increasing the degree of cure without compromising the film viscosity for good wettability or water sorption and solubility. Fillers increased the elastic modulus, tensile strength and fracture toughness to a plateau between 5 and 15wt% filler concentration, and despite the tendency to form agglomerations, active crack pinning/deflection toughening mechanisms have been observed. The bond strength between resin composite and dentin was also improved when adhesives with up to 10wt% fillers were used, with no additional improvements with further packing. The use of fillers to reinforce dental adhesives may therefore be of great practical benefit by improving curing and mechanical properties.

  20. Influence of surface roughness on gecko adhesion.

    PubMed

    Huber, Gerrit; Gorb, Stanislav N; Hosoda, Naoe; Spolenak, Ralph; Arzt, Eduard

    2007-07-01

    In this study we show the influence of surface roughness on gecko adhesion on both the nano- and macroscales. We present experimental data for the force necessary to pull off single spatulae from hard rough substrates and also detail observations on living geckos clinging to various surfaces. Both experiments consistently show that the effective adhesion shows a minimum for a root mean square roughness ranging from 100 to 300nm.

  1. New pressure-sensitive silicone adhesive

    NASA Technical Reports Server (NTRS)

    Leiffer, J. L.; Stoops, W. E., Jr.; St. Clair, T. L.; Watkins, V. E., Jr.; Kelly, T. P.

    1981-01-01

    Adhesive for high or low temperatures does not stretch severely under load. It is produced by combining intermediate-molecular-weight pressure sensitive adhesive which does not cure with silicone resin that cures with catalyst to rubbery tack-free state. Blend of silicone tackifier and cured rubbery silicone requires no solvents in either atmospheric or vacuum environments. Ratio of ingredients varies for different degrees of tack, creep resistance, and tensile strength.

  2. Cryogenic adhesives and sealants: Abstracted publications

    NASA Technical Reports Server (NTRS)

    Williamson, F. R.; Olien, N. A.

    1977-01-01

    Abstracts of primary documents containing original experimental data on the properties of adhesives and sealants at cryogenic temperatures are presented. The most important references mentioned in each document are cited. In addition, a brief annotation is given for documents considered secondary in nature, such as republications or variations of original reports, progress reports leading to final reports included as primary documents, and experimental data on adhesive properties at temperatures between about 130 K and room temperature.

  3. Processable polyimide adhesive and matrix composite resin

    NASA Technical Reports Server (NTRS)

    Pratt, J. Richard (Inventor); St.clair, Terry L. (Inventor); Progar, Donald J. (Inventor)

    1990-01-01

    A high temperature polyimide composition prepared by reacting 4,4'-isophthaloyldiphthalic anhydride with metaphenylenediamine is employed to prepare matrix resins, adhesives, films, coatings, moldings, and laminates, especially those showing enhanced flow with retention of mechanical and adhesive properties. It can be used in the aerospace industry, for example, in joining metals to metals or metals to composite structures. One area of application is in the manufacture of lighter and stronger aircraft and spacecraft structures.

  4. Analytical cell adhesion chromatography reveals impaired persistence of metastatic cell rolling adhesion to P-selectin.

    PubMed

    Oh, Jaeho; Edwards, Erin E; McClatchey, P Mason; Thomas, Susan N

    2015-10-15

    Selectins facilitate the recruitment of circulating cells from the bloodstream by mediating rolling adhesion, which initiates the cell-cell signaling that directs extravasation into surrounding tissues. To measure the relative efficiency of cell adhesion in shear flow for in vitro drug screening, we designed and implemented a microfluidic-based analytical cell adhesion chromatography system. The juxtaposition of instantaneous rolling velocities with elution times revealed that human metastatic cancer cells, but not human leukocytes, had a reduced capacity to sustain rolling adhesion with P-selectin. We define a new parameter, termed adhesion persistence, which is conceptually similar to migration persistence in the context of chemotaxis, but instead describes the capacity of cells to resist the influence of shear flow and sustain rolling interactions with an adhesive substrate that might modulate the probability of extravasation. Among cell types assayed, adhesion persistence to P-selectin was specifically reduced in metastatic but not leukocyte-like cells in response to a low dose of heparin. In conclusion, we demonstrate this as an effective methodology to identify selectin adhesion antagonist doses that modulate homing cell adhesion and engraftment in a cell-subtype-selective manner.

  5. Induction of the Gene Encoding Macrophage Chemoattractant Protein 1 by Orientia tsutsugamushi in Human Endothelial Cells Involves Activation of Transcription Factor Activator Protein 1

    PubMed Central

    Cho, Nam-Hyuk; Seong, Seung-Yong; Huh, Myung-Sook; Kim, Na-Hyun; Choi, Myung-sik; Kim, Ik-sang

    2002-01-01

    Human macrophage chemoattractant protein 1 (MCP-1) is a potent mediator of macrophage migration and therefore plays an essential role in early events of inflammation. In endothelial cells, at least three independent pathways regulate MCP-1 expression by NF-κB and AP-1. Orientia tsutsugamushi causes vasculitis in humans by replicating inside macrophages and endothelial cells. In the present study, we investigated the cis-acting and trans-acting elements involved in O. tsutsugamushi-induced MCP-1 gene expression in human umbilical vein endothelial cells (HUVEC). Although NF-κB activation was observed in HUVEC infected with O. tsutsugamushi, inhibition of NF-κB activation did not affect the MCP-1 expression. However, treatment of HUVEC with extracellular signal-regulated kinase (ERK) kinase inhibitor or p38 mitogen-activated protein kinase (MAPK) inhibitor suppressed expression of MCP-1 mRNA concomitant with downregulation of activator protein 1 (AP-1) activation. Deletion of triphorbol acetate response elements (TRE) at position −69 to −63 of MCP-1 gene abolished inducible promoter activity. Deletion of TRE at position −69 to −63−96 to −90 or deletion of NF-κB-binding site at position −69 to −63−88 to −79 did not affect the inducibility of promoter. Site-directed mutagenesis of the NF-κB binding sites at positions −2640 to −2632, −2612 to −2603 in the enhancer region, or the AP-1 biding site at position −2276 to −2270 decreased the inducible activity of the promoter. Taken together, AP-1 activation by both the ERK pathway and the p38 MAPK pathway as well as their binding to TRE at position −69 to −63 in proximal promoter and TRE at position −2276 to −2270 in enhancer region is altogether essential in induction of MCP-1 mRNA in HUVEC infected with O. tsutsugamushi. Although NF-κB activation is not essential per se, the κB site in the enhancer region is important in MCP-1 induction of HUVEC. This discrepancy in the

  6. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Pressure-sensitive adhesives. 175.125 Section 175... Substances for Use Only as Components of Adhesives § 175.125 Pressure-sensitive adhesives. Pressure-sensitive... accordance with the following prescribed conditions: (a) Pressure-sensitive adhesives prepared from one or...

  7. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Pressure-sensitive adhesives. 175.125 Section 175... Substances for Use Only as Components of Adhesives § 175.125 Pressure-sensitive adhesives. Pressure-sensitive... accordance with the following prescribed conditions: (a) Pressure-sensitive adhesives prepared from one or...

  8. 21 CFR 175.125 - Pressure-sensitive adhesives.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Pressure-sensitive adhesives. 175.125 Section 175...) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for Use Only as Components of Adhesives § 175.125 Pressure-sensitive adhesives....

  9. Single-molecule mechanics of mussel adhesion

    NASA Astrophysics Data System (ADS)

    Lee, Haeshin; Scherer, Norbert F.; Messersmith, Phillip B.

    2006-08-01

    The glue proteins secreted by marine mussels bind strongly to virtually all inorganic and organic surfaces in aqueous environments in which most adhesives function poorly. Studies of these functionally unique proteins have revealed the presence of the unusual amino acid 3,4-dihydroxy-L-phenylalanine (dopa), which is formed by posttranslational modification of tyrosine. However, the detailed binding mechanisms of dopa remain unknown, and the chemical basis for mussels' ability to adhere to both inorganic and organic surfaces has never been fully explained. Herein, we report a single-molecule study of the substrate and oxidation-dependent adhesive properties of dopa. Atomic force microscopy (AFM) measurements of a single dopa residue contacting a wet metal oxide surface reveal a surprisingly high strength yet fully reversible, noncovalent interaction. The magnitude of the bond dissociation energy as well as the inability to observe this interaction with tyrosine suggests that dopa is critical to adhesion and that the binding mechanism is not hydrogen bond formation. Oxidation of dopa, as occurs during curing of the secreted mussel glue, dramatically reduces the strength of the interaction to metal oxide but results in high strength irreversible covalent bond formation to an organic surface. A new picture of the interfacial adhesive role of dopa emerges from these studies, in which dopa exploits a remarkable combination of high strength and chemical multifunctionality to accomplish adhesion to substrates of widely varying composition from organic to metallic. 3,4-dihydroxylphenylalanine | atomic force microscopy | mussel adhesive protein

  10. Cell-Substrate Adhesion by Amoeboid Cells

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Panta, Krishna

    Amoeboid migration is a rapid (10 μm min-1) mode of migration that some tumor cells exhibit. To permit such rapid movement, the adhesive contacts between the cell and the substrate must be relatively short-lived and weak. In this study, we investigate the basic adhesive character of amoeboid cells (D. discoideum) in contact with silanized glass substrates. We observe the initiation and spreading of the adhesive contacts that these cells establish as they settle under gravity onto the substrate and relax towards mechanical equilibrium. The use of interference reflection microscopy and cellular tethering measurements have allowed us to determine the basic adhesive properties of the cell: the membrane-medium interfacial energy; the bending modulus; the equilibrium contact angle; and the work of adhesion. We find the time scale on which settling occurs to be longer than expected. Implications of these results on adhesion and migration will be discussed. The authors are grateful for support from NSF (CBET-1451903) and NIH (1R21EY026392).

  11. Factors influencing bacterial adhesion to contact lenses

    PubMed Central

    Dutta, Debarun; Willcox, Mark

    2012-01-01

    The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria. PMID:22259220

  12. Biomechanism of adhesion in gecko setae.

    PubMed

    Guo, Ce; Sun, Jiurong; Ge, Yingbin; Wang, Wenbo; Wang, Dapeng; Dai, Zhendong

    2012-02-01

    The study of the adhesion of millions of setae on the toes of geckos has been advanced in recent years with the emergence of new technology and measurement methods. The theory of the mechanism of adhesion by van der Waals forces is now accepted and broadly understood. However, this paper presents limitations of this theory and gives a new hypothesis of the biomechanism of gecko adhesion. The findings are obtained through measurements of the magnitude of the adhesion of setae under three different conditions, to show the close relationship between adhesion and status of the setae. They are reinforced by demonstrating two setal structures, follicle cells and hair, the former making the setae capable of producing bioelectrical charges, which play an important role in attachment and detachment processes. It is shown that the abundant muscular tissues at the base of the setae cells, which are controlled by peripheral nerves, are instrumental in producing the foot movement involved in attachment and detachment. Our study will further uncover the adhesion mechanism of geckos, and provide new ideas for designing and fabricating synthetic setae.

  13. Yielding elastic tethers stabilize robust cell adhesion.

    PubMed

    Whitfield, Matt J; Luo, Jonathon P; Thomas, Wendy E

    2014-12-01

    Many bacteria and eukaryotic cells express adhesive proteins at the end of tethers that elongate reversibly at constant or near constant force, which we refer to as yielding elasticity. Here we address the function of yielding elastic adhesive tethers with Escherichia coli bacteria as a model for cell adhesion, using a combination of experiments and simulations. The adhesive bond kinetics and tether elasticity was modeled in the simulations with realistic biophysical models that were fit to new and previously published single molecule force spectroscopy data. The simulations were validated by comparison to experiments measuring the adhesive behavior of E. coli in flowing fluid. Analysis of the simulations demonstrated that yielding elasticity is required for the bacteria to remain bound in high and variable flow conditions, because it allows the force to be distributed evenly between multiple bonds. In contrast, strain-hardening and linear elastic tethers concentrate force on the most vulnerable bonds, which leads to failure of the entire adhesive contact. Load distribution is especially important to noncovalent receptor-ligand bonds, because they become exponentially shorter lived at higher force above a critical force, even if they form catch bonds. The advantage of yielding is likely to extend to any blood cells or pathogens adhering in flow, or to any situation where bonds are stretched unequally due to surface roughness, unequal native bond lengths, or conditions that act to unzip the bonds.

  14. Controlled Adhesion of Silicone Elastomer Surfaces

    NASA Astrophysics Data System (ADS)

    Owen, Michael

    2000-03-01

    Opportunities exist for controllably enhancing the adhesion of silicone surfaces, ranging from modest enhancement of release force levels of pressure-sensitive adhesive (PSA) release liners by incorporation of adhesion promoters known as high release additives (HRA), to permanent bonding of silicone elastomers using surface modification techniques such as plasma or corona treatment. Although only a part of the complex interaction of factors contributing to adhesion, surface properties such as wettability are a critical component in the understanding and control of release and adhesion phenomena. Surface characterization studies of low-surface-energy silicones before and after various adhesion modification strategies are reviewed. The silicones include polydimethylsiloxane (PDMS) and fluorosiloxane elastomers and coatings. Techniques used include contact angle, the Johnson, Kendall and Roberts (JKR) contact mechanics approach, scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Topics addressed are: use of HRA in PDMS release liners, the interaction of PDMS PSAs with polytetrafluoroethylene (PTFE), and the effect of plasma treatment on PDMS and fluorosiloxane surfaces.

  15. Design guidelines for hybrid microcircuits; organic adhesives for hybrid microcircuits

    NASA Technical Reports Server (NTRS)

    Perkins, K. L.; Licari, J. J.

    1975-01-01

    The properties of organic adhesives were studied to acquire an adequate information base to generate a guideline document for the selection of adhesives for use in high reliability hybrid microcircuits. Specific areas covered include: (1) alternate methods for determining the outgassing of cured adhesives; (2) effects of long term aging at 150C on the electrical properties of conductive adhesives; (3) effects of shelf life age on adhesive characteristics; (4) bond strengths of electrically conductive adhesives on thick film gold metallization, (5) a copper filled adhesive; (6) effects of products outgassed from cured adhesives on device electrical parameters; (7) metal migration from electrically conductive adhesives; and (8) ionic content of electrically insulative adhesives. The tests performed during these investigations are described, and the results obtained are discussed in detail.

  16. Contribution from pressure-sensitive adhesives

    NASA Astrophysics Data System (ADS)

    Cunningham, Gilbert

    1996-03-01

    The successful use of many security papers, foils and films depends on the technology of chemical fastening systems -- especially pressure sensitive adhesives. These are adhesives activated not by heat or by the evaporation of water or some other solvent, but simply by the act of application -- by pressure. These adhesives provide the means whereby laminations, substrates and seals are made effective. In addition to their physical properties these adhesives are often required to possess optical properties to allow the security materials to be visibly active and indeed the adhesive system may itself contribute as a carrier for a variety of security materials. Recent advances in adhesives chemistry have made it possible to achieve virtually all the required physical performance characteristics combined with a choice of optical properties ranging from total opacity to invisibility and including controlled translucency and tinting. The implications for security printing and packaging are important. Opacity is easy to achieve, for example by loading the adhesive with aluminum powder, by the selection of totally opaque materials like metallized film or by various printing processes. But achieving transparency is a different matter, and transparency is mandatory for applications involving the protection of documents, photographs, etc. with a clear film over-laminate. Obvious examples would be for passports, visas and other personal identification. But some security devices may themselves require protection; for example holograms or embossings. And transparency in the test laboratory is not enough. The Australian driving licence is stuck to the windshield, so the transparency of the adhesive must be sustained over long periods without deterioration due to prolonged u/v exposure, climatic conditions or aging. The commercial label market has helped to push the technology forward. There is a strong demand for the 'no-label look' for packaging of clear plastic and glass

  17. Sargaquinoic Acid Inhibits TNF-α-Induced NF-κB Signaling, Thereby Contributing to Decreased Monocyte Adhesion to Human Umbilical Vein Endothelial Cells (HUVECs).

    PubMed

    Gwon, Wi-Gyeong; Lee, Bonggi; Joung, Eun-Ji; Choi, Min-Woo; Yoon, Nayoung; Shin, Taisun; Oh, Chul-Woong; Kim, Hyeung-Rak

    2015-10-21

    Sargaquinoic acid (SQA) has been known for its antioxidant and anti-inflammatory properties. This study investigated the effects of SQA isolated from Sargassum serratifolium on the inhibition of tumor necrosis factor (TNF)-α-induced monocyte adhesion to human umbilical vein endothelial cells (HUVECs). SQA decreased the expression of cell adhesion molecules such as intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 as well as chemotactic cytokines such as interleukin-8 and monocyte chemoattractant protein-1 in TNF-α-treated HUVECs. As a result, SQA prevented monocyte adhesion to TNF-α-induced adhesion. SQA also inhibited TNF-α-induced nuclear factor kappa B (NF-κB) translocation into the nucleus by preventing proteolytic degradation of inhibitor κB-α. Overall, SQA protects against TNF-α-induced vascular inflammation through inhibition of the NF-κB pathway in HUVECs. These data suggest that SQA may be used as a therapeutic agent for vascular inflammatory diseases such as atherosclerosis. PMID:26437568

  18. Hydrogen peroxide activates activator protein-1 and mitogen-activated protein kinases in pancreatic stellate cells.

    PubMed

    Kikuta, Kazuhiro; Masamune, Atsushi; Satoh, Masahiro; Suzuki, Noriaki; Satoh, Kennichi; Shimosegawa, Tooru

    2006-10-01

    Activated pancreatic stellate cells (PSCs) are implicated in the pathogenesis of pancreatic inflammation and fibrosis, where oxidative stress is thought to play a key role. Reactive oxygen species such as hydrogen peroxide (H(2)O(2)) may act as a second messenger to mediate the actions of growth factors and cytokines. But the role of reactive oxygen species in the activation and regulation of cell functions in PSCs remains largely unknown. We here examined the effects of H(2)O(2) on the activation of signal transduction pathways and cell functions in PSCs. PSCs were isolated from the pancreas of male Wistar rats, and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. Activation of transcription factors was examined by electrophoretic mobility shift assay and luciferase assay. Activation of mitogen-activated protein (MAP) kinases was assessed by Western blotting using anti-phosphospecific antibodies. The effects of H(2)O(2) on proliferation, alpha(1)(I)procollagen gene expression, and monocyte chemoattractant protein-1 production were evaluated. The effect of H(2)O(2) on the transformation of freshly isolated PSCs in culture was also assessed. H(2)O(2) at non-cytotoxic concentrations (up to 100 microM) induced oxidative stress in PSCs. H(2)O(2) activated activator protein-1, but not nuclear factor kappaB. In addition, H(2)O(2) activated three classes of MAP kinases: extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 MAP kinase. H(2)O(2) induced alpha(1)(I)procollagen gene expression but did not induce proliferation or monocyte chemoattractant protein-1 production. H(2)O(2) did not initiate the transformation of freshly isolated PSCs to myofibroblast-like phenotype. Specific activation of these signal transduction pathways and collagen gene expression by H(2)O(2) may play a role in the pathogenesis of pancreatic fibrosis.

  19. Adhesion of latex films. Influence of surfactants

    SciTech Connect

    Charmeau, J.Y.; Kientz, E.; Holl, Y.

    1996-12-31

    In the applications of film forming latexes in paint, paper, coating, adhesive, textile industries, one of the most important property of latex films is adhesion onto a support. From the point of view of adhesion, latex films have two specificities. The first one arises from the particular structure of the film which is usually not homogeneous but retains to a certain extent the memory of the particles it was made from. These structure effects are clearly apparent when one compares mechanical or adhesion properties of pure latex films and of films of the same polymers but prepared from a solution. Latex films show higher Young`s moduli and lower adhesion properties than solution films. The second specificity of latex films comes from the presence of the surfactant which was used in the synthesis and as stabilizer for the latex. Most industrial latexes contain low amounts of surfactant, typically in the range 0.1 to 2-3 wt%. However, being usually incompatible with the polymer, the surfactant is not homogeneously distributed in the film. It tends to segregate towards the film-air or film-support interfaces or to form domains in the bulk of the film. Distribution of surfactants in latex films has been studied by several authors. The influence of the surfactant on adhesion, as well as on other properties, is thus potentially very important. This article presents the results of the authors investigation of surfactant effects on adhesion properties of latex films. To the authors knowledge, there is no other example, in the open literature, of this kind of study.

  20. Multidrug resistance protein 1 (MRP1, ABCC1), a "multitasking" ATP-binding cassette (ABC) transporter.

    PubMed

    Cole, Susan P C

    2014-11-01

    The multidrug resistance protein 1 (MRP1) encoded by ABCC1 was originally discovered as a cause of multidrug resistance in tumor cells. However, it is now clear that MRP1 serves a broader role than simply mediating the ATP-dependent efflux of drugs from cells. The antioxidant GSH and the pro-inflammatory cysteinyl leukotriene C4 have been identified as key physiological organic anions effluxed by MRP1, and an ever growing body of evidence indicates that additional lipid-derived mediators are also substrates of this transporter. As such, MRP1 is a multitasking transporter that likely influences the etiology and progression of a host of human diseases.

  1. Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins

    PubMed Central

    Petrone, Luigi; Kumar, Akshita; Sutanto, Clarinda N.; Patil, Navinkumar J.; Kannan, Srinivasaraghavan; Palaniappan, Alagappan; Amini, Shahrouz; Zappone, Bruno; Verma, Chandra; Miserez, Ali

    2015-01-01

    Interfacial water constitutes a formidable barrier to strong surface bonding, hampering the development of water-resistant synthetic adhesives. Notwithstanding this obstacle, the Asian green mussel Perna viridis attaches firmly to underwater surfaces via a proteinaceous secretion (byssus). Extending beyond the currently known design principles of mussel adhesion, here we elucidate the precise time-regulated secretion of P. viridis mussel adhesive proteins. The vanguard 3,4-dihydroxy-L-phenylalanine (Dopa)-rich protein Pvfp-5 acts as an adhesive primer, overcoming repulsive hydration forces by displacing surface-bound water and generating strong surface adhesion. Using homology modelling and molecular dynamics simulations, we find that all mussel adhesive proteins are largely unordered, with Pvfp-5 adopting a disordered structure and elongated conformation whereby all Dopa residues reside on the protein surface. Time-regulated secretion and structural disorder of mussel adhesive proteins appear essential for optimizing extended nonspecific surface interactions and byssus' assembly. Our findings reveal molecular-scale principles to help the development of wet-resistant adhesives. PMID:26508080

  2. Cadherin-11 localizes to focal adhesions and promotes cell–substrate adhesion

    PubMed Central

    Langhe, Rahul P.; Gudzenko, Tetyana; Bachmann, Michael; Becker, Sarah F.; Gonnermann, Carina; Winter, Claudia; Abbruzzese, Genevieve; Alfandari, Dominique; Kratzer, Marie-Claire; Franz, Clemens M.; Kashef, Jubin

    2016-01-01

    Cadherin receptors have a well-established role in cell–cell adhesion, cell polarization and differentiation. However, some cadherins also promote cell and tissue movement during embryonic development and tumour progression. In particular, cadherin-11 is upregulated during tumour and inflammatory cell invasion, but the mechanisms underlying cadherin-11 stimulated cell migration are still incompletely understood. Here, we show that cadherin-11 localizes to focal adhesions and promotes adhesion to fibronectin in Xenopus neural crest, a highly migratory embryonic cell population. Transfected cadherin-11 also localizes to focal adhesions in different mammalian cell lines, while endogenous cadherin-11 shows focal adhesion localization in primary human fibroblasts. In focal adhesions, cadherin-11 co-localizes with β1-integrin and paxillin and physically interacts with the fibronectin-binding proteoglycan syndecan-4. Adhesion to fibronectin mediated by cadherin-11/syndecan-4 complexes requires both the extracellular domain of syndecan-4, and the transmembrane and cytoplasmic domains of cadherin-11. These results reveal an unexpected role of a classical cadherin in cell–matrix adhesion during cell migration. PMID:26952325

  3. Cadherin-11 localizes to focal adhesions and promotes cell-substrate adhesion.

    PubMed

    Langhe, Rahul P; Gudzenko, Tetyana; Bachmann, Michael; Becker, Sarah F; Gonnermann, Carina; Winter, Claudia; Abbruzzese, Genevieve; Alfandari, Dominique; Kratzer, Marie-Claire; Franz, Clemens M; Kashef, Jubin

    2016-01-01

    Cadherin receptors have a well-established role in cell-cell adhesion, cell polarization and differentiation. However, some cadherins also promote cell and tissue movement during embryonic development and tumour progression. In particular, cadherin-11 is upregulated during tumour and inflammatory cell invasion, but the mechanisms underlying cadherin-11 stimulated cell migration are still incompletely understood. Here, we show that cadherin-11 localizes to focal adhesions and promotes adhesion to fibronectin in Xenopus neural crest, a highly migratory embryonic cell population. Transfected cadherin-11 also localizes to focal adhesions in different mammalian cell lines, while endogenous cadherin-11 shows focal adhesion localization in primary human fibroblasts. In focal adhesions, cadherin-11 co-localizes with β1-integrin and paxillin and physically interacts with the fibronectin-binding proteoglycan syndecan-4. Adhesion to fibronectin mediated by cadherin-11/syndecan-4 complexes requires both the extracellular domain of syndecan-4, and the transmembrane and cytoplasmic domains of cadherin-11. These results reveal an unexpected role of a classical cadherin in cell-matrix adhesion during cell migration. PMID:26952325

  4. Mussel adhesion is dictated by time-regulated secretion and molecular conformation of mussel adhesive proteins

    NASA Astrophysics Data System (ADS)

    Petrone, Luigi; Kumar, Akshita; Sutanto, Clarinda N.; Patil, Navinkumar J.; Kannan, Srinivasaraghavan; Palaniappan, Alagappan; Amini, Shahrouz; Zappone, Bruno; Verma, Chandra; Miserez, Ali

    2015-10-01

    Interfacial water constitutes a formidable barrier to strong surface bonding, hampering the development of water-resistant synthetic adhesives. Notwithstanding this obstacle, the Asian green mussel Perna viridis attaches firmly to underwater surfaces via a proteinaceous secretion (byssus). Extending beyond the currently known design principles of mussel adhesion, here we elucidate the precise time-regulated secretion of P. viridis mussel adhesive proteins. The vanguard 3,4-dihydroxy-L-phenylalanine (Dopa)-rich protein Pvfp-5 acts as an adhesive primer, overcoming repulsive hydration forces by displacing surface-bound water and generating strong surface adhesion. Using homology modelling and molecular dynamics simulations, we find that all mussel adhesive proteins are largely unordered, with Pvfp-5 adopting a disordered structure and elongated conformation whereby all Dopa residues reside on the protein surface. Time-regulated secretion and structural disorder of mussel adhesive proteins appear essential for optimizing extended nonspecific surface interactions and byssus' assembly. Our findings reveal molecular-scale principles to help the development of wet-resistant adhesives.

  5. The de-adhesive activity of matricellular proteins: is intermediate cell adhesion an adaptive state?

    PubMed

    Murphy-Ullrich, J E

    2001-04-01

    The process of cellular de-adhesion is potentially important for the ability of a cell to participate in morphogenesis and to respond to injurious stimuli. Cellular de-adhesion is induced by the highly regulated matricellular proteins TSP1 and 2, tenascin-C, and SPARC. These proteins induce a rapid transition to an intermediate state of adhesiveness characterized by loss of actin-containing stress fibers and restructuring of the focal adhesion plaque that includes loss of vinculin and alpha-actinin, but not of talin or integrin. This process involves intracellular signaling mediators, which are engaged in response to matrix protein-receptor interactions. Each of these proteins employs different receptors and signaling pathways to achieve this common morphologic endpoint. What is the function of this intermediate adhesive state and what is the physiologic significance of this action of the matricellular proteins? Given that matricellular proteins are expressed in response to injury and during development, one can speculate that the intermediate adhesive state is an adaptive condition that facilitates expression of specific genes that are involved in repair and adaptation. Since cell shape is maintained in weakly adherent cells, this state might induce survival signals to prevent apoptosis due to loss of strong cell adhesion, but yet allow for cell locomotion. The three matricellular proteins considered here might each preferentially facilitate one or more aspects of this adaptive response rather than all of these equally. Currently, we have only preliminary data to support the specific ideas proposed in this article. It will be interesting in the next several years to continue to elucidate the biological roles of the intermediate adhesive state induced by these matricellular proteins. and focal adhesions in a cell that nevertheless maintains a spread, extended morphology and integrin clustering. TSP1, tenascin-C, and SPARC induce the intermediate adhesive state, as

  6. BIOLOGICAL ADHESIVES. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement.

    PubMed

    Maier, Greg P; Rapp, Michael V; Waite, J Herbert; Israelachvili, Jacob N; Butler, Alison

    2015-08-01

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (E(ad) ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a "one-two punch," whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides. PMID:26250681

  7. Role of tilted adhesion fibrils (setae) in the adhesion and locomotion of gecko-like systems.

    PubMed

    Zhao, Boxin; Pesika, Noshir; Zeng, Hongbo; Wei, Zhensong; Chen, Yunfei; Autumn, Kellar; Turner, Kimberly; Israelachvili, Jacob

    2009-03-26

    Geckos are super climbers: they can readily and rapidly stick to almost any surface, whether hydrophilic or hydrophobic, rough or smooth, in dry or wet conditions, and detach with equal rapidity within tens of milliseconds. In this paper, we discuss the rapid switching between the strong adhesion/friction (attached) state and zero adhesion/friction (detached) state, and present a finite element analysis of gecko setae in terms of their adhesion and friction forces. The analysis shows why the asymmetric, naturally curved setae with a directional tilt play a crucial role in the gecko's articulation mechanism, consistent with recent experimental studies of gecko setal arrays. We derive guidelines for designing synthetic versions of gecko adhesive pads, and propose a design for a "gecko-inspired" adhesive surface consisting of arrays of curved, asymmetric, and directionally oriented microfibrils, attached to a semirigid backing, and suggest a method for its actuation.

  8. The effect of polyethylene glycol adhesion barrier (Spray Gel) on preventing peritoneal adhesions.

    PubMed

    Dasiran, F; Eryilmaz, R; Isik, A; Okan, I; Somay, A; Sahin, M

    2015-01-01

    The prominent cells in the late phase of wound healing during proliferation and matrix deposition are fibroblasts. Foreign materials in the operation site like prosthesis prolong the inflammation and induce fibroblast proliferation (8). 3 different prostheses used in this study induced chronic inflammation and fibrosis and provided an effective repair. Dense and thick adhesions due to fibrosis also induced strong adhesions to omentum and small intestine if only polypropylene mesh used for hernia repair. However, there was no difference between SprayGel treated polypropylene mesh and Sepramesh when compared for fibrosis. It also prevents the intraabdominal adhesion formation. It is nontoxic, sticky adherent, non- immigrant and easy to use both in open and laparoscopic surgeries. This experimental study revealed that polyethyleneglycol applied polypropylene mesh accomplishes hernia repair with significantly less adhesion formation than polypropylene mesh alone while securing a remarkable economy than adhesion barrier coated dual meshes (Tab. 6, Fig. 7, Ref. 23). Text in PDF www.elis.sk. PMID:26084740

  9. Shear Strength of Conductive Adhesive Joints on Rigid and Flexible Substrates Depending on Adhesive Quantity

    NASA Astrophysics Data System (ADS)

    Hirman, Martin; Steiner, Frantisek

    2016-05-01

    This article deals with the impact of electrically conductive adhesive quantity on the shear strength of joints glued by adhesives "EPO-TEKⓇ H20S" and "MG8331S" on three types of substrates (FR-4, MELINEXⓇST504, DuPont™ PyraluxⓇAC). These joints were made by gluing chip resistors 1206, 0805 and 0603, with two curing profiles for each adhesive. Different thicknesses of stencil and reductions in the size of the hole in stencils were used for this experiment. These differences have an effect on the quantity of conductive adhesives which must be used on the samples. Samples were measured after the curing process by using a shear strength test applied by the device LabTest 3.030. This article presents the effects of different curing profiles, various types of substrates, and different quantities of adhesives on the mechanical strength of the joint.

  10. Supramolecular adhesives to hard surfaces: adhesion between host hydrogels and guest glass substrates through molecular recognition.

    PubMed

    Takashima, Yoshinori; Sahara, Taiga; Sekine, Tomoko; Kakuta, Takahiro; Nakahata, Masaki; Otsubo, Miyuki; Kobayashi, Yuichiro; Harada, Akira

    2014-10-01

    Supramolecular materials based on host-guest interactions should exhibit high selectivity and external stimuli-responsiveness. Among various stimuli, redox and photo stimuli are useful for its wide application. An external stimuli-responsive adhesive system between CD host-gels (CD gels) and guest molecules modified glass substrates (guest Sub) is focused. Here, the selective adhesion between host gels and guest substrates where adhesion depends on molecular complementarity is reported. Initially, it is thought that adhesion of a gel material onto a hard material might be difficult unless many guest molecules modified linear polymers immobilize on the surface of hard materials. However, reversible adhesion of the CD gels is observed by dissociating and re-forming inclusion complex in response to redox and photo stimuli.

  11. BIOLOGICAL ADHESIVES. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement.

    PubMed

    Maier, Greg P; Rapp, Michael V; Waite, J Herbert; Israelachvili, Jacob N; Butler, Alison

    2015-08-01

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (E(ad) ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a "one-two punch," whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides.

  12. Ultrasonic Nondestructive Characterization of Adhesive Bonds

    NASA Technical Reports Server (NTRS)

    Qu, Jianmin

    1999-01-01

    Adhesives and adhesive joints are widely used in various industrial applications to reduce weight and costs, and to increase reliability. For example, advances in aerospace technology have been made possible, in part, through the use of lightweight materials and weight-saving structural designs. Joints, in particular, have been and continue to be areas in which weight can be trimmed from an airframe through the use of novel attachment techniques. In order to save weight over traditional riveted designs, to avoid the introduction of stress concentrations associated with rivet holes, and to take full advantage of advanced composite materials, engineers and designers have been specifying an ever-increasing number of adhesively bonded joints for use on airframes. Nondestructive characterization for quality control and remaining life prediction has been a key enabling technology for the effective use of adhesive joints. Conventional linear ultrasonic techniques generally can only detect flaws (delamination, cracks, voids, etc) in the joint assembly. However, more important to structural reliability is the bond strength. Although strength, in principle, cannot be measured nondestructively, a slight change in material nonlinearity may indicate the onset of failure. Furthermore, microstructural variations due to aging or under-curing may also cause changes in the third order elastic constants, which are related to the ultrasonic nonlinear parameter of the polymer adhesive. It is therefore reasonable to anticipate a correlation between changes in the ultrasonic nonlinear acoustic parameter and the remaining bond strength. It has been observed that higher harmonics of the fundamental frequency are generated when an ultrasonic wave passes through a nonlinear material. It seems that such nonlinearity can be effectively used to characterize bond strength. Several theories have been developed to model this nonlinear effect. Based on a microscopic description of the nonlinear

  13. Elasto-capillarity in insect fibrillar adhesion.

    PubMed

    Gernay, Sophie; Federle, Walter; Lambert, Pierre; Gilet, Tristan

    2016-08-01

    The manipulation of microscopic objects is challenging because of high adhesion forces, which render macroscopic gripping strategies unsuitable. Adhesive footpads of climbing insects could reveal principles relevant for micro-grippers, as they are able to attach and detach rapidly during locomotion. However, the underlying mechanisms are still not fully understood. In this work, we characterize the geometry and contact formation of the adhesive setae of dock beetles (Gastrophysa viridula) by interference reflection microscopy. We compare our experimental results to the model of an elastic beam loaded with capillary forces. Fitting the model to experimental data yielded not only estimates for seta adhesion and compliance in agreement with previous direct measurements, but also previously unknown parameters such as the volume of the fluid meniscus and the bending stiffness of the tip. In addition to confirming the primary role of surface tension for insect adhesion, our investigation reveals marked differences in geometry and compliance between the three main kinds of seta tips in leaf beetles. PMID:27488250

  14. Characterizing Cell Adhesion by Using Micropipette Aspiration

    PubMed Central

    Hogan, Brenna; Babataheri, Avin; Hwang, Yongyun; Barakat, Abdul I.; Husson, Julien

    2015-01-01

    We have developed a technique to directly quantify cell-substrate adhesion force using micropipette aspiration. The micropipette is positioned perpendicular to the surface of an adherent cell and a constant-rate aspiration pressure is applied. Since the micropipette diameter and the aspiration pressure are our control parameters, we have direct knowledge of the aspiration force, whereas the cell behavior is monitored either in brightfield or interference reflection microscopy. This setup thus allows us to explore a range of geometric parameters, such as projected cell area, adhesion area, or pipette size, as well as dynamical parameters such as the loading rate. We find that cell detachment is a well-defined event occurring at a critical aspiration pressure, and that the detachment force scales with the cell adhesion area (for a given micropipette diameter and loading rate), which defines a critical stress. Taking into account the cell adhesion area, intrinsic parameters of the adhesion bonds, and the loading rate, a minimal model provides an expression for the critical stress that helps rationalize our experimental results. PMID:26200857

  15. Adhesive curing options for photonic packaging

    NASA Astrophysics Data System (ADS)

    Martin, Steven C.; Hubert, Manfred; Tam, Robin

    2002-06-01

    Varying the intensity of illumination used to cure photoactivated adhesives has been applied in medical and dental applications to improve the performance of polymer materials. For example, it has been observed that dental polymer composite materials express reduced shrinkage, important for durability of non-amalgam restorations, by introducing a phased time-intensity cure schedule. This work identified that curing conditions could influence the final properties of materials, and suggested the possibility of extending the characteristics that could be influenced beyond shrinkage to humidity resistance, Tg, outgassing and other important material properties. Obviously, these results have important ramifications for the photonic industry, with current efforts focused on improved manufacturing techniques. Improvement in low cost packaging solutions, including adhesives, will have to be made to bring the component cost down to address the needs of Metro and similar markets. However, there are perceived problems with the widespread use of adhesives, the most prevalent of these involving long term durability of the bond. Devices are typically aligned to sub-micron precision using active feedback and then must be locked in position to maintain performance. In contrast to traditional fastening methods, adhesive bonding is a highly attractive option due to the ease of deployment, lower equipment costs, and improved flexibility. Moreover, using methods analogous to those employed in dental applications, materials properties of photonic adhesives may be tailored using a programmed cure approach.

  16. Spiders Tune Glue Viscosity to Maximize Adhesion.

    PubMed

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali

    2015-11-24

    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives.

  17. Actin Foci Adhesion of D. discoideum

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Paneru, Govind

    2014-03-01

    Amoeboid migration is a fast (10 μm min-1) integrin-independent mode of migration that is important with D. discoideum, leukocytes, and breast cancer cells. It is poorly understood, but depends on the establishment of adhesive contacts to the substrate where the cell transmits traction forces. In pre-aggregative D. discoideum, a model system for learning about amoeboid migration, these adhesive contacts are discrete complexes that are known as actin-foci. They have an area of ~ 0.5 μm2 and a lifetime of ~ 20 s. This talk will present measurements of the adhesive character of actin foci that have been obtained using a submicron force transducer that was designed for this purpose. Results on the rupture stresses and lifetimes of individual acting foci under nano-newton level forces will be described in the context of a general theory for cellular adhesion. This theory depends on, essentially, three cellular properties: the membrane-medium surface tension, the number density of adhesion receptors in the membrane, and the receptor-substrate potential energy surface. Therefore, the use of the transducer to determine the surface tension will be presented, as well.

  18. Tumorigenic and adhesive properties of heparanase

    PubMed Central

    Levy-Adam, Flonia; Ilan, Neta; Vlodavsky, Israel

    2010-01-01

    Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains presumably at sites of low sulfation, activity that is strongly implicated with cell invasion associated with cancer metastasis, a consequence of structural modification that loosens the extracellular matrix barrier. In addition, heparanase exerts pro-adhesive properties, mediated by clustering of membrane heparan sulfate proteoglycans (i.e., syndecans) and activation of signaling molecules such as Akt, Src, EGFR, and Rac in a heparan sulfate-dependent and -independent manner. Activation of signaling cascades by enzymatically inactive heparanase and by a peptide corresponding to its substrate binding domain not only increases cell adhesion but also facilitates cancer cell growth. This notion is supported by preclinical and clinical settings, encouraging the development of anti-heparanase therapeutics. Here we summarize recent progress in heparanase research emphasizing the molecular mechanisms that govern its pro-tumorigenic and pro-adhesive properties. Pro-adhesive properties of the heparanase homolog, heparanase 2 (Hpa2), are also discussed. Enzymatic activity-independent function of proteases (i.e., matrix metalloproteinases) is discussed in the context of cell adhesion and tumor progression. Collectively, these examples suggest that enzyme function exceeds beyond the enzymatic aspect, thus significantly expanding the scope of the functional proteome. Cross-talk with matrix metalloproteinases and the role of heparanase in pathological settings other than cancer is also described. PMID:20619346

  19. Elasto-capillarity in insect fibrillar adhesion.

    PubMed

    Gernay, Sophie; Federle, Walter; Lambert, Pierre; Gilet, Tristan

    2016-08-01

    The manipulation of microscopic objects is challenging because of high adhesion forces, which render macroscopic gripping strategies unsuitable. Adhesive footpads of climbing insects could reveal principles relevant for micro-grippers, as they are able to attach and detach rapidly during locomotion. However, the underlying mechanisms are still not fully understood. In this work, we characterize the geometry and contact formation of the adhesive setae of dock beetles (Gastrophysa viridula) by interference reflection microscopy. We compare our experimental results to the model of an elastic beam loaded with capillary forces. Fitting the model to experimental data yielded not only estimates for seta adhesion and compliance in agreement with previous direct measurements, but also previously unknown parameters such as the volume of the fluid meniscus and the bending stiffness of the tip. In addition to confirming the primary role of surface tension for insect adhesion, our investigation reveals marked differences in geometry and compliance between the three main kinds of seta tips in leaf beetles.

  20. Spiders Tune Glue Viscosity to Maximize Adhesion.

    PubMed

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali

    2015-11-24

    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives. PMID:26513350

  1. Probing adhesion forces at the molecular scale

    SciTech Connect

    Thomas, R.C.; Houston, J.E.; Michalske, T.A.

    1996-12-31

    Measurements of adhesion forces at the molecular scale, such as those discussed here, are necessary to understand macroscopic boundary-layer behavior such as adhesion, friction, wear, lubrication, and many other important phenomena. The authors` recent interfacial force microscopy (IFM) studies have provided detailed information about the mechanical response of both self-assembled monolayer (SAM) films and the underlying substrates. In addition, they recently demonstrated that the IFM is useful for studying the chemical nature of such films. In this talk, the authors discuss a new method for studying surface interactions and chemical reactions using the IFM. To quantitatively measure the work of adhesion and bond energies between two organic thin films, they modify both a Au substrate and a Au probe with self-assembling organomercaptan molecules having either the same or different end groups (-CH{sub 3}, -NH{sub 2}, and -COOH), and then analyze the force-versus-displacement curves (force profiles) that result from the approach to contact of the two surfaces. Their results show that the magnitude of the adhesive forces measured between methyl-methyl interactions are in excellent agreement with van der Waals calculations using Lifshitz theory and previous experimentally determined values. Moreover, the measured peak adhesive forces scale as expected for van der Waals, hydrogen-bonding, and acid-base interactions.

  2. Dextran and gelatin based photocrosslinkable tissue adhesive.

    PubMed

    Wang, Tao; Nie, Jun; Yang, Dongzhi

    2012-11-01

    A two-component tissue adhesive based on biocompatible and bio-degradable polymers (oxidized urethane dextran (Dex-U-AD) and gelatin) was prepared and photocrosslinked under the ultraviolet (UV) irradiation. The adhesive could adhere to surface of gelatin, which simulated the human tissue steadily. The structures of above Dex-U-AD were characterized by FTIR, (1)H NMR spectroscopy and XRD. The adhesion property of result products was evaluated by lap-shear test. The maximum adhesion strength could reach to 4.16±0.72 MPa which was significantly higher than that of fibrin glue. The photopolymerization process of Dex-U-AD/gelatin was monitored by real time infrared spectroscopy (RTIR). It took less than 5 min to complete the curing process. The cytotoxicity of Dex-U-AD/gelatin also was evaluated which indicated that Dex-U-AD/gelatin gels were nontoxic to L929 cell. The relationship between all the above-mentioned properties and degree of oxidization of Dex-U-AD was assessed. The obtained products have the potential to serve as tissue adhesive in the future.

  3. Accommodation of structural rearrangements in the huntingtin-interacting protein 1 coiled-coil domain

    SciTech Connect

    Wilbur, Jeremy D.; Hwang, Peter K.; Brodsky, Frances M.; Fletterick, Robert J.

    2010-03-01

    Variable packing interaction related to the conformational flexibility within the huntingtin-interacting protein 1 coiled coil domain. Huntingtin-interacting protein 1 (HIP1) is an important link between the actin cytoskeleton and clathrin-mediated endocytosis machinery. HIP1 has also been implicated in the pathogenesis of Huntington’s disease. The binding of HIP1 to actin is regulated through an interaction with clathrin light chain. Clathrin light chain binds to a flexible coiled-coil domain in HIP1 and induces a compact state that is refractory to actin binding. To understand the mechanism of this conformational regulation, a high-resolution crystal structure of a stable fragment from the HIP1 coiled-coil domain was determined. The flexibility of the HIP1 coiled-coil region was evident from its variation from a previously determined structure of a similar region. A hydrogen-bond network and changes in coiled-coil monomer interaction suggest that the HIP1 coiled-coil domain is uniquely suited to allow conformational flexibility.

  4. Epilepsy, Behavioral Abnormalities, and Physiological Comorbidities in Syntaxin-Binding Protein 1 (STXBP1) Mutant Zebrafish

    PubMed Central

    Grone, Brian P.; Marchese, Maria; Hamling, Kyla R.; Kumar, Maneesh G.; Krasniak, Christopher S.; Sicca, Federico; Santorelli, Filippo M.; Patel, Manisha; Baraban, Scott C.

    2016-01-01

    Mutations in the synaptic machinery gene syntaxin-binding protein 1, STXBP1 (also known as MUNC18-1), are linked to childhood epilepsies and other neurodevelopmental disorders. Zebrafish STXBP1 homologs (stxbp1a and stxbp1b) have highly conserved sequence and are prominently expressed in the larval zebrafish brain. To understand the functions of stxbp1a and stxbp1b, we generated loss-of-function mutations using CRISPR/Cas9 gene editing and studied brain electrical activity, behavior, development, heart physiology, metabolism, and survival in larval zebrafish. Homozygous stxbp1a mutants exhibited a profound lack of movement, low electrical brain activity, low heart rate, decreased glucose and mitochondrial metabolism, and early fatality compared to controls. On the other hand, homozygous stxbp1b mutants had spontaneous electrographic seizures, and reduced locomotor activity response to a movement-inducing “dark-flash” visual stimulus, despite showing normal metabolism, heart rate, survival, and baseline locomotor activity. Our findings in these newly generated mutant lines of zebrafish suggest that zebrafish recapitulate clinical phenotypes associated with human syntaxin-binding protein 1 mutations. PMID:26963117

  5. Human climbing with efficiently scaled gecko-inspired dry adhesives.

    PubMed

    Hawkes, Elliot W; Eason, Eric V; Christensen, David L; Cutkosky, Mark R

    2015-01-01

    Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for synthetic materials, so can gecko adhesion systems provide a baseline for scaling efficiency. In the tokay gecko (Gekko gecko), a scaling power law has been reported relating the maximum shear stress σmax to the area A: σmax ∝ A(-1/4). We present a mechanical concept which improves upon the gecko's non-uniform load-sharing and results in a nearly even load distribution over multiple patches of gecko-inspired adhesive. We created a synthetic adhesion system incorporating this concept which shows efficient scaling across four orders of magnitude of area, yielding an improved scaling power law: σmax ∝ A(-1/50). Furthermore, we found that the synthetic adhesion system does not fail catastrophically when a simulated failure is induced on a portion of the adhesive. In a practical demonstration, the synthetic adhesion system enabled a 70 kg human to climb vertical glass with 140 cm(2) of adhesive per hand.

  6. Design and fabrication of gecko-inspired adhesives.

    PubMed

    Jin, Kejia; Tian, Yu; Erickson, Jeffrey S; Puthoff, Jonathan; Autumn, Kellar; Pesika, Noshir S

    2012-04-01

    Recently, there has been significant interest in developing dry adhesives mimicking the gecko adhesive system, which offers several advantages compared to conventional pressure-sensitive adhesives. Specifically, gecko adhesive pads have anisotropic adhesion properties; the adhesive pads (spatulae) stick strongly when sheared in one direction but are non-adherent when sheared in the opposite direction. This anisotropy property is attributed to the complex topography of the array of fine tilted and curved columnar structures (setae) that bear the spatulae. In this study, we present an easy, scalable method, relying on conventional and unconventional techniques, to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provides anisotropic adhesion properties. We measured the anisotropic adhesion and friction properties of samples with various tilt angles to test the validity of a nanoscale tape-peeling model of spatular function. Consistent with the peel zone model, samples with lower tilt angles yielded larger adhesion forces. The tribological properties of the synthetic arrays were highly anisotropic, reminiscent of the frictional adhesion behavior of gecko setal arrays. When a 60° tilt sample was actuated in the gripping direction, a static adhesion strength of ~1.4 N/cm(2) and a static friction strength of ~5.4 N/cm(2) were obtained. In contrast, when the dry adhesive was actuated in the releasing direction, we measured an initial repulsive normal force and negligible friction.

  7. Human climbing with efficiently scaled gecko-inspired dry adhesives

    PubMed Central

    Hawkes, Elliot W.; Eason, Eric V.; Christensen, David L.; Cutkosky, Mark R.

    2015-01-01

    Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for synthetic materials, so can gecko adhesion systems provide a baseline for scaling efficiency. In the tokay gecko (Gekko gecko), a scaling power law has been reported relating the maximum shear stress σmax to the area A: σmax ∝ A−1/4. We present a mechanical concept which improves upon the gecko's non-uniform load-sharing and results in a nearly even load distribution over multiple patches of gecko-inspired adhesive. We created a synthetic adhesion system incorporating this concept which shows efficient scaling across four orders of magnitude of area, yielding an improved scaling power law: σmax ∝ A−1/50. Furthermore, we found that the synthetic adhesion system does not fail catastrophically when a simulated failure is induced on a portion of the adhesive. In a practical demonstration, the synthetic adhesion system enabled a 70 kg human to climb vertical glass with 140 cm2 of adhesive per hand. PMID:25411404

  8. Thermal Characterization of Epoxy Adhesive by Hotfire Testing

    NASA Technical Reports Server (NTRS)

    Spomer, Ken A.; Haddock, M. Reed; McCool, Alex (Technical Monitor)

    2001-01-01

    This paper describes subscale solid-rocket motor hot-fire testing of epoxy adhesives in flame surface bondlines to evaluate heat-affected depth, char depth and ablation rate. Hot-fire testing is part of an adhesive down-selection program on the Space Shuttle Solid Rocket Motor Nozzle to provide additional confidence in the down-selected adhesives. The current nozzle structural adhesive bond system is being replaced due to obsolescence. Prior to hot-fire testing, adhesives were tested for chemical, physical and mechanical properties, which resulted in the selection of two potential replacement adhesives, Resin Technology Group's TIGA 321 and 3M's EC2615XLW. Hot-fire testing consisted of four forty-pound charge (FPC) motors fabricated in configurations that would allow side-by-side comparison testing of the candidate replacement adhesives with the current RSRM adhesives. Results of the FPC motor testing show that: 1) the phenolic char depths on radial bondlines is approximately the same and vary depending on the position in the blast tube regardless of which adhesive was used, 2) the replacement candidate adhesive char depths are equivalent to the char depths of the current adhesives, 3) the heat-affected depths of the candidate and current adhesives are equivalent, and 4) the ablation rates for both replacement adhesives were equivalent to the current adhesives.

  9. Surface tension and deformation in soft adhesion

    NASA Astrophysics Data System (ADS)

    Jensen, Katharine

    Modern contact mechanics was originally developed to account for the competition between adhesion and elasticity for relatively stiff deformable materials like rubber, but much softer sticky materials are ubiquitous in biology, engineering, and everyday consumer products. In such soft materials, the solid surface tension can also play an important role in resisting shape change, and significantly modify the physics of contact with soft matter. We report indentation and pull-off experiments that bring small, rigid spheres into adhesive contact with compliant silicone gel substrates, varying both the surface functionalization of the spheres and the bulk elastic properties of the gels. We map the resulting deformation profiles using optical microscopy and image analysis. We examine the substrate geometry in light of capillary and elastic theories in order to explore the interplay of surface tension and bulk elasticity in governing soft adhesion.

  10. Laparoscopic Management of Adhesive Small Bowel Obstruction

    PubMed Central

    Konjic, Ferid; Idrizovic, Enes; Hasukic, Ismar; Jahic, Alen

    2016-01-01

    Introduction: Adhesions are the reason for bowel obstruction in 80% of the cases. In well selected patients the adhesive ileus laparoscopic treatment has multiple advantages which include the shorter hospitalization period, earlier food taking, and less postoperative morbidity rate. Case report: Here we have a patient in the age of 35 hospitalized at the clinic due to occlusive symptoms. Two years before an opened appendectomy had been performed on him. He underwent the treatment of exploration laparoscopy and laparoscopic adhesiolysis. Dilated small bowel loops connected with the anterior abdominal wall in the ileocecal region by adhesions were found intraoperatively and then resected harmonically with scalpel. One strangulation around which a small bowel loop was wrapped around was found and dissected. Postoperative course was normal. PMID:27041815

  11. Optimizing Scale Adhesion on Single Crystal Superalloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Pint, Bruce A.

    2000-01-01

    To improve scale adhesion, single crystal superalloys have been desulfurized to levels below 1 ppmw by hydrogen annealing. A transition to fully adherent behavior has been shown to occur at a sulfur level of about 0.2 ppmw, as demonstrated for PWA 1480, PWA 1484, and Rene N5 single crystal superalloys in 1100-1150 C cyclic oxidation tests up to 2000 h. Small additions of yttrium (15 ppmw) also have been effective in producing adhesion for sulfur contents of about 5 ppmw. Thus the critical Y/S ratio required for adhesion was on the order of 3-to-1 by weight (1-to-1 atomic), in agreement with values estimated from solubility products for yttrium sulfides. While hydrogen annealing greatly improved an undoped alloy, yielding <= 0.01 ppmw S, it also produced benefits for Y-doped alloys without measurably reducing the sulfur content.

  12. [Inhibition of neutrophil adhesion by pectic galacturonans].

    PubMed

    Popov, S V; Ovodova, R G; Popova, G Iu; Nikitina, I R; Ovodov, Iu S

    2007-01-01

    The inhibition of the adhesion of neutrophils to fibronectin by the fragments of the main galacturonan chain of the following pectins was demonstrated: comaruman from the marsh cinquefoil Comarum polustre, bergenan from the Siberian tea Bergenia crassifolia, lemnan from the duckweed Lemna minor, zosteran from the seagrass Zostera marina, and citrus pectin. The parent pectins, except for comaruman, did not affect the cell adhesion. Galacturonans prepared from the starting pectins by acidic hydrolysis were shown to reduce the neutrophil adhesion stimulated by phorbol 12-myristate 13-acetate (1.625 microM) and dithiothreitol (0.5 mM) at a concentration of 50-200 microg/ml. The presence of carbohydrate chains with molecular masses higher than 300, from 100 to 300, and from 50 to 100 kDa in the galacturonan fractions was proved by membrane ultrafiltration. PMID:17375675

  13. Biologically Inspired Mushroom-Shaped Adhesive Microstructures

    NASA Astrophysics Data System (ADS)

    Heepe, Lars; Gorb, Stanislav N.

    2014-07-01

    Adhesion is a fundamental phenomenon with great importance in technology, in our everyday life, and in nature. In this article, we review physical interactions that resist the separation of two solids in contact. By using examples of biological attachment systems, we summarize and categorize various principles that contribute to the so-called gecko effect. Emphasis is placed on the contact geometry and in particular on the mushroom-shaped geometry, which is observed in long-term biological adhesive systems. Furthermore, we report on artificial model systems with this bio-inspired geometry and demonstrate that surface microstructures with this geometry are promising candidates for technical applications, in which repeatable, reversible, and residue-free adhesion under different environmental conditions—such as air, fluid, and vacuum—is required. Various applications in robotic systems and in industrial pick-and-place processes are discussed.

  14. Water based adhesive primers on aluminum substrates

    SciTech Connect

    Wightman, J.P.; Mori, S.

    1996-12-31

    The number of aluminum alloy bonding applications has been increasing recently in the automobile industry. Primer coating of aluminum substrates is one of the main processes used to promote bond performance. Solvent based organic primers have been used for a long time but environmental regulations now require the substitution of volatile organic compounds (VOC) by alternate materials such as water based adhesive primers. However, the bond strengths obtained with many water based primers are generally lower than for solvent based ones. Water based primers which have some reactive functional groups have been proposed recently but such primers require special treatment. This paper describes a study conducted to optimize bond strength using a water based adhesive as a primer in the adhesive bonding of anodized aluminum.

  15. Coatings for rubber bonding and paint adhesion

    NASA Astrophysics Data System (ADS)

    Boulos, M. S.; Petschel, M.

    1997-08-01

    Conversion coatings form an important base for the adhesion of paint to metal substrates and for the bonding of rubber to metal parts. Four types of conversion coatings were assessed as base treatments for the bonding of rubber to steel and for the corrosion protection of metal substrates under paint: amorphous iron phosphate, heavy zinc phosphate, and three types of modified zinc phosphates that utilized one or more metal cations in addition to zinc. When applied, these conversion coatings formed a thin film over the metal substrate that was characterized by scanning electron microscopy, x-ray diffraction, and chemical methods. The performance of the coatings was assessed using physical methods such as dry adhesion, conical mandrel, impact, and stress adhesion for the rubber-bonded parts, and by corrosion resistance methods such as humidity, salt spray, and cyclic corrosion. Coating characterization and performance were correlated.

  16. Adhesive bacterial colonization of exposed traumatized tendon.

    PubMed

    Webb, L X; Hobgood, C D; Meredith, J W; Gristina, A G

    1987-05-01

    Recent studies of compromised or damaged tissues, as well as biomaterials, have shown that they provide a particularly fertile substratum for bacterial colonization. Colonization in these environments is mediated by a process of microbial adhesion to surfaces of the substrata. In this report, we present electron microscopic studies of a portion of damaged and infected tendon. These studies demonstrate colonies of bacteria surrounded by a ruthenium red-staining exopolysaccharide biofilm and adhesion to the surface of the tendon by means of an exopolysaccharide polymer. We suggest that this adhesive form of bacterial colonization may partially explain the resistance of exposed tendon to effective debridement by simple mechanical measures and to coverage with granulation tissue, partial-thickness skin grafts, and vascularized tissue grafts.

  17. Fracture of composite-adhesive-composite systems

    NASA Technical Reports Server (NTRS)

    Ripling, E. J.; Santner, J. S.; Crosley, P. B.

    1984-01-01

    This program was undertaken to initiate the development of a test method for testing adhesive joints in metal-adhesive-composite systems. The uniform double cantilever beam (UDCB) and the width tapered beam (WTB) specimen geometries were evaluated for measuring Mode I fracture toughness in these systems. The WTB specimen is the preferred geometry in spite of the fact that it is more costly to machine than the UDCB specimen. The use of loading tabs attached to thin sheets of composites proved to be experimentally unsatisfactory. Consequently, a new system was developed to load thin sheets of adherends. This system allows for the direct measurement of displacement along the load line. In well made joints separation occurred between the plies rather than in the adhesive.

  18. Clinical status of ten dentin adhesive systems.

    PubMed

    Van Meerbeek, B; Peumans, M; Verschueren, M; Gladys, S; Braem, M; Lambrechts, P; Vanherle, G

    1994-11-01

    Laboratory testing of dentin adhesive systems still requires corroboration by long-term clinical trials for their ultimate clinical effectiveness to be validated. The objective of this clinical investigation was to evaluate, retrospectively, the clinical effectiveness of earlier-investigated dentin adhesive systems (Scotchbond, Gluma, Clearfil New Bond, Scotchbond 2, Tenure, and Tripton), and to compare their clinical results with those obtained with four modern total-etch adhesive systems (Bayer exp. 1 and 2, Clearfil Liner Bond System, and Scotchbond Multi-Purpose). In total, 1177 Class V cervical lesions in the teeth of 346 patients were restored following two cavity designs: In Group A, enamel was neither beveled nor intentionally etched, as per ADA guidelines; in Group B, adjacent enamel was beveled and conditioned. Clinical retention rates definitely indicated the improved clinical efficacy of the newest dentin adhesives over the earlier systems. With regard to adhesion strategy, adhesive systems that removed the smear layer and concurrently demineralized the dentin surface layer performed clinically better than systems that modified the disorderly layer of smear debris without complete removal. Hybridization by resin interdiffusion into the exposed dentinal collagen layer, combined with attachment of resin tags into the opened dentin tubules, appeared to be essential for reliable dentin bonding but might be insufficient by itself. The additional formation of an elastic bonding area as a polymerization shrinkage absorber and the use of a microfine restorative composite apparently guaranteed an efficient clinical result. The perfect one-year retention recorded for Clearfil Liner Bond System and Scotchbond Multi-Purpose must be confirmed at later recalls. PMID:7983255

  19. High-Temperature Adhesive Strain Gage Developed

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Roberts, Gary D.

    1997-01-01

    Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

  20. Molecular mechanics of mussel adhesion proteins

    NASA Astrophysics Data System (ADS)

    Qin, Zhao; Buehler, Markus J.

    2014-01-01

    Mussel foot protein (mfp), a natural glue produced by marine mussel, is an intriguing material because of its superior ability for adhesion in various environments. For example, a very small amount of this material is sufficient to affix a mussel to a substrate in water, providing structural support under extreme forces caused by the dynamic effects of waves. Towards a more complete understanding of its strength and underwater workability, it is necessary to understand the microscropic mechanisms by which the protein structure interacts with various substrates. However, none of the mussel proteins' structure is known, preventing us from directly using atomistic modeling to probe their structural and mechanical properties. Here we use an advanced molecular sampling technique to identify the molecular structures of two mussel foot proteins (mfp-3 and mfp-5) and use those structures to study their mechanics of adhesion, which is then incorporated into a continuum model. We calculate the adhesion energy of the mussel foot protein on a silica substrate, compute the adhesion strength based on results obtained from molecular modeling, and compare with experimental data. Our results show good agreement with experimental measurements, which validates the multiscale model. We find that the molecular structure of the folded mussel foot protein (ultimately defined by its genetic sequence) favors strong adhesion to substrates, where L-3,4-dihydroxyphenylalanine (or DOPA) protein subunits work in a cooperative manner to enhance adhesion. Our experimental data suggests a peak attachment force of 0.4±0.1 N, which compares favorably with the prediction from the multiscale model of Fc=0.21-0.33 N. The principles learnt from those results could guide the fabrication of new interfacial materials (e.g. composites) to integrate organic with inorganic surfaces in an effective manner.

  1. Urokinase does not prevent abdominal adhesion formation in rats.

    PubMed

    Rivkind, A I; Lieberman, N; Durst, A L

    1985-01-01

    Damage to the fibrinolytic system preventing the resolution of temporary fibrinous adhesions was repeatedly mentioned as an etiological factor in the process of adhesion formation. We experimentally induced abdominal adhesions in rats by gentle scraping of the entire small bowel. Severe adhesions, sometimes accompanied by intestinal obstruction, developed in all of the control animals. Urokinase, a commonly used and potent fibrinolytic agent and a known plasminogen activator, was administered intragastrically, intraperitoneally, or intravenously at various doses ranging from 5,000 to 100,000 U/kg. Urokinase had no effect on the prevention of abdominal adhesions, nor did it reduce the severity or frequency of adhesion formation. PMID:4043158

  2. Analysis of adhesively bonded composite lap joints

    SciTech Connect

    Tong, L.; Kuruppu, M.; Kelly, D.

    1994-12-31

    A new nonlinear formulation is developed for the governing equations for the shear and peel stresses in adhesively bonded composite double lap joints. The new formulation allows arbitrary nonlinear stress-strain characteristics in both shear and peel behavior. The equations are numerically integrated using a shooting technique and Newton-Raphson method behind a user friendly interface. The failure loads are predicted by utilizing the maximum stress criterion, interlaminar delamination and the energy density failure criteria. Numerical examples are presented to demonstrate the effect of the nonlinear adhesive behavior on the stress distribution and predict the failure load and the associated mode.

  3. Treatment of adhesive capsulitis: a review

    PubMed Central

    D’Orsi, Giovanni Maria; Via, Alessio Giai; Frizziero, Antonio; Oliva, Francesco

    2012-01-01

    Summary Adhesive capsulitis is a condition “difficult to define, difficult to treat and difficult to explain from the point of view of pathology”. This Codman’s assertion is still actual because of a variable nomenclature, an inconsistent reporting of disease staging and many types of treatment. There is no consensus on how the best way best to manage patients with this condition, so we want to provide an evidence-based overview regarding the effectiveness of conservative and surgical interventions to treat adhesive capsulitis. PMID:23738277

  4. Surgical Adhesives in Facial Plastic Surgery.

    PubMed

    Toriumi, Dean M; Chung, Victor K; Cappelle, Quintin M

    2016-06-01

    In facial plastic surgery, attaining hemostasis may require adjuncts to traditional surgical techniques. Fibrin tissue adhesives have broad applications in surgery and are particularly useful when addressing the soft tissue encountered in facial plastic surgery. Beyond hemostasis, tissue adhesion and enhanced wound healing are reported benefits associated with a decrease in operating time, necessity for drains and pressure dressings, and incidence of wound healing complications. These products are clinically accessible to most physicians who perform facial plastic surgery, including skin grafts, flaps, rhytidectomy, and endoscopic forehead lift. PMID:27267012

  5. [Investigation on bovine leukocyte adhesion deficiency].

    PubMed

    Ma, Jin-Zhu; Cui, Yu-Dong; Zhu, Zhan-Bo; Cao, Hong-Wei; Piao, Fan-Ze

    2006-10-01

    Bovine leukocyte adhesion deficiency (BLAD) is autosomal recessive disease. The pathogeny of BLAD is genic mutation of CD18-integrins on the leukocyte. In order to know the carrier and occurrence of bovine leukocyte adhesion deficiency (BLAD) among cows age from one to six years old in China, 1,000 cows were investigated by means of amplifying a CD18 gene fragment via reverse transcriptase-PCR followed by restriction digestion with Taq I. Results showed that 19 cows were BLAD carriers, indicating that the BLAD carrier rate was 1.9 percent. In addition, one cow was found to have BLAD. PMID:17035180

  6. Method of measuring metal coating adhesion

    DOEpatents

    Roper, John R.

    1985-01-01

    A method for measuring metal coating adhesion to a substrate material comprising the steps of preparing a test coupon of substrate material having the metal coating applied to one surface thereof, applying a second metal coating of gold or silver to opposite surfaces of the test coupon by hot hollow cathode process, applying a coating to one end of each of two pulling rod members, joining the coated ends of the pulling rod members to said opposite coated surfaces of the test coupon by a solid state bonding technique and finally applying instrumented static tensile loading to the pulling rod members until fracture of the metal coating adhesion to the substrate material occurs.

  7. Physics of cell elasticity, shape and adhesion

    NASA Astrophysics Data System (ADS)

    Safran, S. A.; Gov, N.; Nicolas, A.; Schwarz, U. S.; Tlusty, T.

    2005-07-01

    We review recent theoretical work that analyzes experimental measurements of the shape, fluctuations and adhesion properties of biological cells. Particular emphasis is placed on the role of the cytoskeleton and cell elasticity and we contrast the shape and adhesion of elastic cells with fluid-filled vesicles. In red blood cells (RBC), the cytoskeleton consists of a two-dimensional network of spectrin proteins. Our analysis of the wavevector and frequency dependence of the fluctuation spectrum of RBC indicates that the spectrin network acts as a confining potential that reduces the fluctuations of the lipid bilayer membrane. However, since the cytoskeleton is only sparsely connected to the bilayer, one cannot regard the composite cytoskeleton-membrane as a polymerized object with a shear modulus. The sensitivity of RBC fluctuations and shapes to ATP concentration may reflect topological defects induced in the cytoskeleton network by ATP. The shapes of cells that adhere to a substrate are strongly determined by the cytoskeletal elasticity that can be varied experimentally by drugs that depolymerize the cytoskeleton. This leads to a tension-driven retraction of the cell body and a pearling instability of the resulting ray-like protrusions. Recent experiments have shown that adhering cells exert polarized forces on substrates. The interactions of such “force dipoles” in either bulk gels or on surfaces can be used to predict the nature of self-assembly of cell aggregates and may be important in the formation of artificial tissues. Finally, we note that cell adhesion strongly depends on the forces exerted on the adhesion sites by the tension of the cytoskeleton. The size and shape of the adhesion regions are strongly modified as the tension is varied and we present an elastic model that relates this tension to deformations that induce the recruitment of new molecules to the adhesion region. In all these examples, cell shape and adhesion differ from vesicle shape and

  8. Friction and adhesion of hierarchical carbon nanotube structures for biomimetic dry adhesives: multiscale modeling.

    PubMed

    Hu, Shihao; Jiang, Haodan; Xia, Zhenhai; Gao, Xiaosheng

    2010-09-01

    With unique hierarchical fibrillar structures on their feet, gecko lizards can walk on vertical walls or even ceilings. Recent experiments have shown that strong binding along the shear direction and easy lifting in the normal direction can be achieved by forming unidirectional carbon nanotube array with laterally distributed tips similar to gecko's feet. In this study, a multiscale modeling approach was developed to analyze friction and adhesion behaviors of this hierarchical fibrillar system. Vertically aligned carbon nanotube array with laterally distributed segments at the end was simulated by coarse grained molecular dynamics. The effects of the laterally distributed segments on friction and adhesion strengths were analyzed, and further adopted as cohesive laws used in finite element analysis at device scale. The results show that the laterally distributed segments play an essential role in achieving high force anisotropy between normal and shear directions in the adhesives. Finite element analysis reveals a new friction-enhanced adhesion mechanism of the carbon nanotube array, which also exists in gecko adhesive system. The multiscale modeling provides an approach to bridge the microlevel structures of the carbon nanotube array with its macrolevel adhesive behaviors, and the predictions from this modeling give an insight into the mechanisms of gecko-mimicking dry adhesives.

  9. A randomized control clinical trial of fissure sealant retention: Self etch adhesive versus total etch adhesive

    PubMed Central

    Aman, Nadia; Khan, Farhan Reza; Salim, Aisha; Farid, Huma

    2015-01-01

    Context: There are limited studies on comparison of Total etch (TE) and Self etch (SE) adhesive for placement of sealants. Aims: The aim of the study was to compare the retention of fissure sealants placed using TE adhesive to those sealants placed using SE (seventh generation) adhesive. Settings and Design: The study was conducted in the dental section, Aga Khan University Hospital. This study was a randomized single blinded trial with a split mouth design. Materials and Methods: The study included 37 patients, 101 teeth were included in both study groups. The intervention arm was treated with SE Adhesive (Adper Easy One, 3M ESPE, US). Control arm received TE adhesive (Adper Single Bond 2, 3M ESPE, US) before sealant application. The patients were followed after 6 months for assessment of sealant retention. Statistical analysis used: Interexaminer agreement for outcome assessment was assessed by Kappa Statistics and outcome in intervention group was assessed by McNemar's test. Results: Ninety-one pairs of molar (90%) were reevaluated for sealant retention. Complete retention was 56% in TE arm and 28% in SE arm with an odds ratio (OR) of 3.7. Conclusions: Sealants applied with TE adhesives show higher rate of complete sealant retention than SE adhesive. PMID:25657521

  10. Differential adhesiveness between blood and marrow leukemic cells having similar pattern of VLA adhesion molecule expression.

    PubMed

    Thomas, X; Anglaret, B; Bailly, M; Maritaz, O; Magaud, J P; Archimbaud, E

    1998-10-01

    Functional adhesion of blood and marrow leukemic cells from 14 acute myeloid leukemia patients presenting with hyperleukocytosis was evaluated by performing cytoadhesion assays on purified (extracellular matrix proteins) and non-purified supports (MRC5 fibroblastic cell line). Results, in 30-min chromium release assay, show a mean +/- S.D. adhesion to fibronectin, collagen, and laminin respectively of 30 +/- 17%, 20 +/- 13%, 25 +/- 17% for blood leukemic cells and 18 +/- 11%, 11 +/- 10%, 11 +/- 8% for marrow leukemic cells. These differences between blood and marrow cells were statistically significant (respectively P = 0.005, P = 0.01 and P = 0.002), while no difference was noted regarding adhesion to non-purified supports. The higher adhesion of blood blast cells to purified supports was observed regardless of CD34 expression. No significant difference was observed in the expression of cell surface VLA-molecules (CD29, CD49b, CD49d, CD49e, CD49f) between blood and marrow blast cells. The addition of GM-CSF or G-CSF induced increased adhesion of marrow blasts and decreased adhesion of blood blasts leading to a loss of the difference between blood and marrow cells. In a 60-min chromium release assay, marrow blasts adhered even more than blood leukemic cells to fibronectin. In contrast, marrow blasts from 'aleukemic' acute myeloid leukemia patients did not show any modification regarding their adhesion to extracellular matrix proteins when co-cultured with growth factors. PMID:9766756

  11. A 90-Kilodalton Endothelial Cell Molecule Mediating Lymphocyte Binding in Humans

    NASA Astrophysics Data System (ADS)

    Salmi, Marko; Jalkanen, Sirpa

    1992-09-01

    Interactions between leukocyte surface receptors and their ligands on vascular endothelial cells control lymphocyte traffic between the blood and various lymphoid organs, as well as extravasation of leukocytes into sites of inflammation. A heretofore undescribed 90-kilodalton human endothelial cell adhesion molecule (VAP-1) defined by a monoclonal antibody 1B2 is described. The expression pattern, molecular mass, functional properties, and an amino-terminal amino acid sequence define VAP-1 as an endothelial ligand for lymphocytes. VAP-1 helps to elucidate the complex heterotypic cell interactions that direct tissue-selective lymphocyte migration in man.

  12. Makorin Ring Finger Protein 1 as Adjunctive Marker in Liquid-based Cervical Cytology

    PubMed Central

    Lee, Maria; Chang, Min Young; Shin, Ha-Yeon; Shin, Eunah; Hong, Sun Won; Kim, Kyung-Mi; Chay, Doo Byung; Cho, Hanbyoul; Kim, Jae-Hoon

    2016-01-01

    Abstract To assess the utility of makorin ring finger protein 1 (MKRN1) as a marker of cervical pathology. A PROspective specimen collection and retrospective Blinded Evaluation study was conducted. Liquid-based cytology samples were collected from 187 women, embedding all residuals as cell blocks for immunohistochemical staining of MKRN1 and P16 INK4a. Results of liquid-based cervical cytology, immunostained cell block sections, and human papillomavirus (HPV) hybrid capture (with real-time polymerase chain reaction) were analyzed. Clinical outcomes were analyzed overall and in subsets of specimens yielding atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesions. Makorin ring finger protein 1 positivity and grades (1–3) of cervical intraepithelial neoplasia (CIN) increased in tandem (CIN1, 32.4%; CIN2, 60.0%; and CIN3, 80.0%), reaching 92.3% in invasive cancer. Sensitivity, specificity, positive predictive value, and negative predictive value in detecting CIN2+ via MKRN1 were 73.8%, 76.8%, 75.6%, and 75.0%, respectively. The performance of liquid-based cytology was poorer by comparison (61.3%, 69.5%, 66.2%, and 64.8%, respectively), and HPV assay (versus MKRN1 immunohistochemical staining) displayed lower specificity (67.7%). Combined HPV + MKRN1 testing proved highest in sensitivity, specificity, positive predictive value, and negative predictive value (71.8%, 85.5%, 82.3%, and 76.5%, respectively), whereas corresponding values for cytology + HPV (60.6%, 81.8%, 75.4%, and 69.2%) and cytology + MKRN1 (58.8%, 84.1%, 78.3%, and 67.7%) were all similar. In instances of atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesions, the HPV + MKRN1 combination performed best by above measures (100%, 72.7%, 73.9%, and 100%), followed by cytology + MKRN1 (100%, 50.0%, 60.7%, and 100%). Makorin ring finger protein 1 displayed greater sensitivity and specificity than liquid

  13. Strong adhesion and friction coupling in hierarchical carbon nanotube arrays for dry adhesive applications.

    PubMed

    Hu, Shihao; Xia, Zhenhai; Gao, Xiaosheng

    2012-04-01

    The adhesion and friction coupling of hierarchical carbon nanotube arrays was investigated with a hierarchical multiscale modeling approach. At device level, vertically aligned carbon nanotube (VA-CNT) arrays with laterally distributed segments on top were analyzed via finite element methods to determine the macroscopic adhesion and friction force coupling. At the nanoscale, molecular dynamics simulation was performed to explore the origin of the adhesion enhancement due to the existence of the laterally distributed CNTs. The results show interfacial adhesion force is drastically promoted by interfacial friction force when a single lateral CNT is being peeled from an amorphous carbon substrate. By fitting with experiments, we find that under shearing loadings the maximum interfacial adhesion force is increased by a factor of ~5, compared to that under normal loadings. Pre-existing surface asperities of the substrate have proven to be the source of generating large interfacial friction, which in turn results in an enhanced adhesion. The critical peeling angles derived from the continuum and nano- levels are comparable to those of geckos and other synthetic adhesives. Our analysis indicates that the adhesion enhancement factor of the hierarchically structured VA-CNT arrays could be further increased by uniformly orienting the laterally distributed CNTs on top. Most importantly, a significant buckling of the lateral CNT at peeling front is captured on the molecular level, which provides a basis for the fundamental understanding of local deformation, and failure mechanisms of nanofibrillar structures. This work gives an insight into the durability issues that prevent the success of artificial dry adhesives.

  14. Monocyte chemotactic protein 1 is released during lethal and sublethal bacteremia in baboons.

    PubMed

    Jansen, P M; van Damme, J; Put, W; de Jong, I W; Taylor, F B; Hack, C E

    1995-06-01

    The chemokine monocyte chemotactic protein 1 (MCP-1) is a cytokine with chemotactic activity specific for mononuclear phagocytes. To investigate the possible involvement of MCP-1 in the pathogenesis of sepsis, its course was studied in baboons challenged intravenously with a sublethal or lethal dose of Escherichia coli. Levels of MCP-1 started to increase in both groups of animals 2 h after injection of E. coli, reaching peak levels 4 and 6 h after a sublethal (186 +/- 21 ng/mL) or a lethal (213 +/- 24 ng/mL) dose, respectively. Levels of MCP-1 correlated significantly with plasma levels of another chemokine, interleukin-8 (IL-8; r = .826. P < .001), suggesting that common stimuli mediate the release of both cytokines in this model.

  15. Molecular basis of cellular localization of poly C binding protein 1 in neuronal cells

    SciTech Connect

    Berry, Andrea M.; Flock, Kelly E.; Loh, Horace H.; Ko, Jane L. . E-mail: kojane@shu.edu

    2006-11-03

    Poly C binding protein 1 (PCBP) is involved in the transcriptional regulation of neuronal mu-opioid receptor gene. In this study, we examined the molecular basis of PCBP cellular/nuclear localization in neuronal cells using EGFP fusion protein. PCBP, containing three KH domains and a variable domain, distributed in cytoplasm and nucleus with a preferential nuclear expression. Domain-deletional analyses suggested the requirement of variable and KH3 domains for strong PCBP nuclear expression. Within the nucleus, a low nucleolar PCBP expression was observed, and PCBP variable domain contributed to this restricted nucleolar expression. Furthermore, the punctate nuclear pattern of PCBP was correlated to its single-stranded (ss) DNA binding ability, with both requiring cooperativity of at least three sequential domains. Collectively, certain PCBP domains thus govern its nuclear distribution and transcriptional regulatory activity in the nucleus of neurons, whereas the low nucleolar expression implicates the disengagement of PCBP in the ribosomal RNA synthesis.

  16. A Critical Role for Cysteine 57 in the Biological Functions of Selenium Binding Protein-1.

    PubMed

    Ying, Qi; Ansong, Emmanuel; Diamond, Alan M; Yang, Wancai

    2015-11-18

    The concentration of selenium-binding protein1 (SBP1) is often lower in tumors than in the corresponding tissue and lower levels have been associated with poor clinical outcomes. SBP1 binds tightly selenium although what role selenium plays in its biological functions remains unknown. Previous studies indicated that cysteine 57 is the most likely candidate amino acid for selenium binding. In order to investigate the role of cysteine 57 in SBP1, this amino acid was altered to a glycine and the mutated protein was expressed in human cancer cells. The SBP1 half-life, as well as the cellular response to selenite cytotoxicity, was altered by this change. The ectopic expression of SBP1(GLY) also caused mitochondrial damage in HCT116 cells. Taken together, these results indicated that cysteine 57 is a critical determinant of SBP1 function and may play a significant role in mitochondrial function.

  17. X-ray Structure of Engineered Human Aortic Preferentially Expressed Protein-1 (APEG-1)

    SciTech Connect

    Manjasetty,B.; Niesen, F.; Scheich, C.; Roske, Y.; Goetz, F.; Behlke, J.; Sievert, V.; Heinemann, U.; Buessow, K.

    2005-01-01

    Arterial smooth muscle cells (SMC) are essential for the formation and function of the cardiovascular system. Abnormalities in their growth can cause a wide range of human disorders such as atherosclerosis, the principal cause for heart failure, thus the leading cause for deaths in the western world. The molecular mechanisms that regulate SMC growth and differentiation are unclear partly due to the lack of specific markers and defined in vitro differentiation systems. The recently discovered Aortic Preferentially Expressed Protein-1 (APEG-1) may serve as a sensitive marker for vascular SMC differentiation. APEG-1 is expressed in differentiated vascular SMC in vivo and was found to be down-regulated rapidly in de-differentiated vascular SMC in vitro and in injured arteries in vivo.

  18. Molecular modeling of the human multidrug resistance protein 1 (MRP1/ABCC1)

    SciTech Connect

    DeGorter, Marianne K.; Conseil, Gwenaelle; Deeley, Roger G.; Campbell, Robert L.; Cole, Susan P.C.

    2008-01-04

    Multidrug resistance protein 1 (MRP1/ABCC1) is a 190 kDa member of the ATP-binding cassette (ABC) superfamily of transmembrane transporters that is clinically relevant for its ability to confer multidrug resistance by actively effluxing anticancer drugs. Knowledge of the atomic structure of MRP1 is needed to elucidate its transport mechanism, but only low resolution structural data are currently available. Consequently, comparative modeling has been used to generate models of human MRP1 based on the crystal structure of the ABC transporter Sav1866 from Staphylococcus aureus. In these Sav1866-based models, the arrangement of transmembrane helices differs strikingly from earlier models of MRP1 based on the structure of the bacterial lipid transporter MsbA, both with respect to packing of the twelve helices and their interactions with the nucleotide binding domains. The functional importance of Tyr{sup 324} in transmembrane helix 6 predicted to project into the substrate translocation pathway was investigated.

  19. Human Cementum Protein 1 induces expression of bone and cementum proteins by human gingival fibroblasts

    SciTech Connect

    Carmona-Rodriguez, Bruno; Alvarez-Perez, Marco Antonio; Narayanan, A. Sampath; Zeichner-David, Margarita; Reyes-Gasga, Jose; Molina-Guarneros, Juan; Garcia-Hernandez, Ana Lilia; Suarez-Franco, Jose Luis; Chavarria, Ivet Gil; Villarreal-Ramirez, Eduardo; Arzate, Higinio . E-mail: harzate@servidor.unam.mx

    2007-07-06

    We recently presented evidence showing that a human cementoblastoma-derived protein, named Cementum Protein 1 (CEMP1) may play a role as a local regulator of cementoblast differentiation and cementum-matrix mineralization. This protein was shown to be expressed by cementoblasts and progenitor cells localized in the periodontal ligament. In this study we demonstrate that transfection of CEMP1 into human gingival fibroblasts (HGF) induces mineralization and expression of bone and cementum-matrix proteins. The transfected HGF cells had higher alkaline phosphatase activity and proliferation rate and they expressed genes for alkaline phosphatase, bone sialoprotein, osteocalcin, osteopontin, the transcription factor Runx2/Cbfa1, and cementum attachment protein (CAP). They also produced biological-type hydroxyapatite. These findings indicate that the CEMP1 might participate in differentiation and mineralization of nonosteogenic cells, and that it might have a potential function in cementum and bone formation.

  20. Amyloid-beta peptide binds to microtubule-associated protein 1B (MAP1B).

    PubMed

    Gevorkian, Goar; Gonzalez-Noriega, Alfonso; Acero, Gonzalo; Ordoñez, Jorge; Michalak, Colette; Munguia, Maria Elena; Govezensky, Tzipe; Cribbs, David H; Manoutcharian, Karen

    2008-05-01

    Extracellular and intraneuronal formation of amyloid-beta aggregates have been demonstrated to be involved in the pathogenesis of Alzheimer's disease. However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of targets have deleterious effects on cellular functions. In the present study we have shown for the first time that amyloid-beta 1-42 bound to a peptide comprising the microtubule binding domain of the heavy chain of microtubule-associated protein 1B by the screening of a human brain cDNA library expressed on M13 phage. This interaction may explain, in part, the loss of neuronal cytoskeletal integrity, impairment of microtubule-dependent transport and synaptic dysfunction observed previously in Alzheimer's disease.

  1. AMYLOID-β PEPTIDE BINDS TO MICROTUBULE-ASSOCIATED PROTEIN 1B (MAP1B)

    PubMed Central

    Gevorkian, Goar; Gonzalez-Noriega, Alfonso; Acero, Gonzalo; Ordoñez, Jorge; Michalak, Colette; Munguia, Maria Elena; Govezensky, Tzipe; Cribbs, David H.; Manoutcharian, Karen

    2008-01-01

    Extracellular and intraneuronal formation of amyloid-beta aggregates have been demonstrated to be involved in the pathogenesis of Alzheimer’s disease. However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of targets have deleterious effects on cellular functions. In the present study we have shown for the first time that amyloid-beta 1-42 bound to a peptide comprising the microtubule binding domain of the heavy chain of microtubule-associated protein 1B by the screening of a human brain cDNA library expressed on M13 phage. This interaction may explain, in part, the loss of neuronal cytoskeletal integrity, impairment of microtubule-dependent transport and synaptic dysfunction observed previously in Alzheimer’s disease. PMID:18079022

  2. Arabidopsis dynamin-related protein 1A polymers bind, but do not tubulate, liposomes

    SciTech Connect

    Backues, Steven K.; Bednarek, Sebastian Y.

    2010-03-19

    The Arabidopsis dynamin-related protein 1A (AtDRP1A) is involved in endocytosis and cell plate maturation in Arabidopsis. Unlike dynamin, AtDRP1A does not have any recognized membrane binding or protein-protein interaction domains. We report that GTPase active AtDRP1A purified from Escherichia coli as a fusion to maltose binding protein forms homopolymers visible by negative staining electron microscopy. These polymers interact with protein-free liposomes whose lipid composition mimics that of the inner leaflet of the Arabidopsis plasma membrane, suggesting that lipid-binding may play a role in AtDRP1A function. However, AtDRP1A polymers do not appear to assemble and disassemble in a dynamic fashion and do not have the ability to tubulate liposomes in vitro, suggesting that additional factors or modifications are necessary for AtDRP1A's in vivo function.

  3. Phosphatidylethanolamine binding protein 1 in vacular endothelial cell autophagy and atherosclerosis

    PubMed Central

    Wang, Li; Li, HaiYing; Zhang, JinFeng; Lu, Wei; Zhao, Jing; Su, Le; Zhao, BaoXiang; Zhang, Yun; Zhang, ShangLi; Miao, JunYing

    2013-01-01

    We previously found that phosphatidylcholine-specific phospholipase C (PC-PLC) was a key inducing element of atherosclerosis, and might negatively regulate human umbilical vein endothelial cell (HUVEC) autophagy. To further investigate the mechanism of PC-PLC action, we initially identified phosphatidylethanolamine binding protein 1 (PEBP1) as a binding partner of PC-PLC by using mass spectrometry (MS, MALDI-TOF/TOF). We found that PEBP1 positively regulated PC-PLC activity in HUVECs, and inhibition of PC-PLC by its inhibitor D609 suppressed PEBP1 expression dramatically. Moreover, both PC-PLC and PEBP1 negatively regulated HUVEC autophagy independently of mammalian target of rapamycin (mTOR). Furthermore, the PEBP1 level was elevated during the development of atherosclerosis, while D609 significantly decreased the upregulated PEBP1 level in apoE−/− mice. PMID:23959677

  4. High-level expression and characterization of a glycosylated human cementum protein 1 with lectin activity.

    PubMed

    Romo-Arévalo, Enrique; Arzate, Higinio; Montoya-Ayala, Gonzalo; Rodríguez-Romero, Adela

    2016-01-01

    This work aims to contribute to the knowledge of human cementum protein 1 (CEMP1), its conformational characteristics and influence during the biomineralization process. The results revealed that hrCEMP1 expressed in Pichia pastoris is a 2.4% glycosylated, thermostable protein which possesses a molecular mass of 28,770 Da. The circular dichroism spectrum indicated a secondary structure content of 28.6% of alpha-helix, 9.9% of beta-sheet and 61.5% of random-coil forms. Biological activity assays demonstrated that hrCEMP1 nucleates and regulates hydroxyapatite crystal growth. Hereby, it is demonstrated for the first time that CEMP1 has a (C-type) lectin-like activity and specifically recognizes mannopyranoside. The information produced by this biochemical and structural characterization may contribute to understand more fully the biological functions of CEMP1.

  5. Regulation of pathogenesis-related protein-1a gene expression in tobacco.

    PubMed

    Uknes, S; Dincher, S; Friedrich, L; Negrotto, D; Williams, S; Thompson-Taylor, H; Potter, S; Ward, E; Ryals, J

    1993-02-01

    Pathogenesis-related protein-1a (PR-1a) is a protein of unknown function that is strongly induced during the onset of systemic acquired resistance (SAR) in tobacco. The expression of PR-1a is under complex regulation that is controlled at least partially by the rate of transcription. In this study, we demonstrated that 661 bp of 5' flanking DNA was sufficient to impart tobacco mosaic virus and salicylic acid inducibility to a reporter gene. The PR-1a promoter did not respond significantly to treatments with either auxin or cytokinin. Experiments with the protein synthesis inhibitor cycloheximide indicated that protein synthesis is required for salicylate-dependent mRNA accumulation. At flowering, the PR-1a gene was expressed primarily in the mesophyll and epidermal tissues of the leaf blade and the sepals of the flower. Several artifacts, most importantly ectopic expression in pollen, were associated with the use of the beta-glucuronidase reporter gene.

  6. Multiple Plasmodium falciparum Merozoite Surface Protein 1 Complexes Mediate Merozoite Binding to Human Erythrocytes.

    PubMed

    Lin, Clara S; Uboldi, Alessandro D; Epp, Christian; Bujard, Hermann; Tsuboi, Takafumi; Czabotar, Peter E; Cowman, Alan F

    2016-04-01

    Successful invasion of human erythrocytes byPlasmodium falciparummerozoites is required for infection of the host and parasite survival. The early stages of invasion are mediated via merozoite surface proteins that interact with human erythrocytes. The nature of these interactions are currently not well understood, but it is known that merozoite surface protein 1 (MSP1) is critical for successful erythrocyte invasion. Here we show that the peripheral merozoite surface proteins MSP3, MSP6, MSPDBL1, MSPDBL2, and MSP7 bind directly to MSP1, but independently of each other, to form multiple forms of the MSP1 complex on the parasite surface. These complexes have overlapping functions that interact directly with human erythrocytes. We also show that targeting the p83 fragment of MSP1 using inhibitory antibodies inhibits all forms of MSP1 complexes and disrupts parasite growthin vitro.

  7. A Critical Role for Cysteine 57 in the Biological Functions of Selenium Binding Protein-1.

    PubMed

    Ying, Qi; Ansong, Emmanuel; Diamond, Alan M; Yang, Wancai

    2015-01-01

    The concentration of selenium-binding protein1 (SBP1) is often lower in tumors than in the corresponding tissue and lower levels have been associated with poor clinical outcomes. SBP1 binds tightly selenium although what role selenium plays in its biological functions remains unknown. Previous studies indicated that cysteine 57 is the most likely candidate amino acid for selenium binding. In order to investigate the role of cysteine 57 in SBP1, this amino acid was altered to a glycine and the mutated protein was expressed in human cancer cells. The SBP1 half-life, as well as the cellular response to selenite cytotoxicity, was altered by this change. The ectopic expression of SBP1(GLY) also caused mitochondrial damage in HCT116 cells. Taken together, these results indicated that cysteine 57 is a critical determinant of SBP1 function and may play a significant role in mitochondrial function. PMID:26593911

  8. Structure of dual function iron regulatory protein 1 complexed with ferritin IRE-RNA

    SciTech Connect

    Walden, William E.; Selezneva, Anna I.; Dupuy, Jérôme; Volbeda, Anne; Fontecilla-Camps, Juan C.; Theil, Elizabeth C.; Volz1, Karl

    2011-07-27

    Iron regulatory protein 1 (IRP1) binds iron-responsive elements (IREs) in messenger RNAs (mRNAs), to repress translation or degradation, or binds an iron-sulfur cluster, to become a cytosolic aconitase enzyme. The 2.8 angstrom resolution crystal structure of the IRP1:ferritin H IRE complex shows an open protein conformation compared with that of cytosolic aconitase. The extended, L-shaped IRP1 molecule embraces the IRE stem-loop through interactions at two sites separated by {approx}30 angstroms, each involving about a dozen protein:RNA bonds. Extensive conformational changes related to binding the IRE or an iron-sulfur cluster explain the alternate functions of IRP1 as an mRNA regulator or enzyme.

  9. The transcription factor X-box binding protein-1 in neurodegenerative diseases

    PubMed Central

    2014-01-01

    Endoplasmic reticulum (ER) is the cellular compartment where secreted and integral membrane proteins are folded and matured. The accumulation of unfolded or misfolded proteins triggers a stress that is physiologically controlled by an adaptative protective response called Unfolded Protein Response (UPR). UPR is primordial to induce a quality control response and to restore ER homeostasis. When this adaptative response is defective, protein aggregates overwhelm cells and affect, among other mechanisms, synaptic function, signaling transduction and cell survival. Such dysfunction likely contributes to several neurodegenerative diseases that are indeed characterized by exacerbated protein aggregation, protein folding impairment, increased ER stress and UPR activation. This review briefly documents various aspects of the biology of the transcription factor XBP-1 (X-box Binding Protein-1) and summarizes recent findings concerning its putative contribution to the altered UPR response observed in various neurodegenerative disorders including Parkinson’s and Alzheimer’s diseases. PMID:25216759

  10. Tubulin polymerization promoting protein 1 (TPPP1): A DNA-damage induced microtubule regulatory gene.

    PubMed

    Schofield, Alice; Bernard, Ora

    2013-11-01

    The eukaryotic cell cycle relies heavily on the mechanical forces vested by the dynamic rearrangement of the microtubule (MT) network. Tubulin Polymerization promoting Protein 1 (TPPP1) alters MT dynamics by driving MT polymerization as well as stabilization, via increasing MT acetylation. It increases MT rigidity, which results in reduced cell proliferation through downregulation of G1/S-phase and mitosis to G1-phase cell cycle transitioning. In this communication, we provide further evidence that TPPP1 may be an important regulator of genomic homeostasis. Our preliminary data show that long-term TPPP1 overexpression reduces cell viability via induction of apoptotic cell death pathways. Moreover, induction of DNA-damage results in increased TPPP1 expression, which is inhibited in the absence of expression of the tumor suppressor p53.

  11. Dynamin-Related Protein 1 Translocates from the Cytosol to Mitochondria during UV-Induced Apoptosis

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenzhen; Wu, Shengnan; Feng, Jie

    2011-01-01

    Mitochondria are dynamic structures that frequently divide and fuse with one another to form interconnecting network. This network disintegrates into punctiform organelles during apoptosis. However, the mechanisms involved in these processes are still not well characterized. In this study, we investigate the role of dynamin-related protein 1 (Drp1), a large GTPase that mediates outer mitochondrial membrane fission, in mitochondrial dynamics in response to UV irradiation in human lung adenocarcinoma cells (ASTC-α-1) and HeLa cells. Using time-lapse fluorescent imaging, we find that Drp1 primarily distributes in cytosol under physiological conditions. After UV treatment, Drp1 translocates from cytosol to mitochondria, indicating the enhancement of Drp1 mitochondrial accumulation. Our results suggest that Drp1 is involved in the regulation of transition from an interconnecting network to a punctiform mitochondrial phenotype during UV-induced apoptosis.

  12. Osteogenic protein-1 (BMP-7) accelerates healing of scaphoid non-union with proximal pole sclerosis

    PubMed Central

    Bilic, R.; Simic, P.; Jelic, M.; Stern-Padovan, R.; Dodig, D.; van Meerdervoort, H. Pompe; Martinovic, S.; Ivankovic, D.; Pecina, M.

    2006-01-01

    We randomly assigned 17 patients with scaphoid non-union at the proximal pole to three treatment groups: (1) autologous iliac graft (n=6), (2) autologous iliac graft + osteogenic protein-1 (OP-1; n=6), and (3) allogenic iliac graft + OP-1 (n=5). Radiographic, scintigraphic, and clinical assessments were performed throughout the follow-up period of 24 months. OP-1 improved the performance of both autologous and allogenic bone implants and reduced radiographic healing time to 4 weeks compared with 9 weeks in group 1. Helical CT scans and scintigraphy showed that in OP-1-treated patients sclerotic bone was replaced by well-vascularised bone. The addition of OP-1 to allogenic bone implant equalised the clinical outcome with the autologous graft procedure. Consequently the harvesting of autologous graft can be avoided. PMID:16506027

  13. Secreted frizzled-related protein 1 regulates adipose tissue expansion and is dysregulated in severe obesity

    PubMed Central

    Lagathu, Claire; Christodoulides, Constantinos; Tan, Chong Yew; Virtue, Sam; Laudes, Matthias; Campbell, Mark; Ishikawa, Ko; Ortega, Francisco; Tinahones, Francisco J.; Fernández-Real, Jose-Manuel; Orešič, Matej; Sethi, Jaswinder K.; Vidal-Puig, Antonio

    2014-01-01

    Aim The Wnt/β-catenin signalling network offers potential targets to diagnose and uncouple obesity from its metabolic complications. Here we investigate the role of the Wnt antagonist, secreted Frizzled related protein 1 (SFRP1) in promoting adipogenesis in vitro and adipose tissue expansion in vivo. Methods We use a combination of human and murine, in vivo and in vitro models of adipogenesis, adipose tissue expansion and obesity-related metabolic syndrome to profile the involvement of SFRP1. Results Secreted Frizzled related protein 1 (SFRP1) is expressed in both murine and human mature adipocytes. The expression of SFRP1 is induced during in vitro adipogenesis and SFRP1 is preferentially expressed in mature adipocytes in human adipose tissue. Constitutive ectopic expression of SFRP1 is proadipogenic and inhibits the Wnt/β-catenin signalling pathway. In vivo endogenous levels of adipose SFRP1 are regulated in line with proadipogenic states. However, in longitudinal studies of high fat diet-fed mice we observed a dynamic temporal but biphasic regulation of endogenous SFRP1. In agreement with this profile we observed that SFRP1 expression in human tissues peaks in patients with mild obesity and gradually falls in morbidly obese subjects. Conclusions Our results suggest that SFRP1 is an endogenous modulator of Wnt/β-catenin signalling and participates in the paracrine regulation of human adipogenesis. The reduced adipose expression of SFRP1 in morbid obesity and its knock-on effect to prevent further adipose tissue expansion may contribute to the development of metabolic complications in these individuals. PMID:20514047

  14. Modulation of Kaposi's Sarcoma-Associated Herpesvirus Interleukin-6 Function by Hypoxia-Upregulated Protein 1

    PubMed Central

    Giffin, Louise; Yan, Feng; Major, M. Ben

    2014-01-01

    ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV, also called human herpesvirus 8) is linked to the development of Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). KSHV expresses several proteins that modulate host cell signaling pathways. One of these proteins is viral interleukin-6 (vIL-6), which is a homolog of human IL-6 (hIL-6). vIL-6 is able to prevent apoptosis and promote proinflammatory signaling, angiogenesis, and cell proliferation. Although it can be secreted, vIL-6 is mainly an intracellular protein that is retained in the endoplasmic reticulum (ER). We performed affinity purification and mass spectrometry to identify novel vIL-6 binding partners and found that a cellular ER chaperone, hypoxia-upregulated protein 1 (HYOU1), interacts with vIL-6. Immunohistochemical staining reveals that both PEL and KS tumor tissues express significant amounts of HYOU1. We also show that HYOU1 increases endogenous vIL-6 protein levels and that HYOU1 facilitates vIL-6-induced JAK/STAT signaling, migration, and survival in endothelial cells. Furthermore, our data suggest that HYOU1 also modulates vIL-6's ability to induce CCL2, a chemokine involved in cell migration. Finally, we investigated the impact of HYOU1 on cellular hIL-6 signaling. Collectively, our data indicate that HYOU1 is important for vIL-6 function and may play a role in the pathogenesis of KSHV-associated cancers. IMPORTANCE KSHV vIL-6 is detectable in all KSHV-associated malignancies and promotes tumorigenesis and inflammation. We identified a cellular protein, called hypoxia-upregulated protein 1 (HYOU1), that interacts with KSHV vIL-6 and is present in KSHV-infected tumors. Our data suggest that HYOU1 facilitates the vIL-6-induced signaling, migration, and survival of endothelial cells. PMID:24920810

  15. Nondestructive Evaluation of Adhesively Bonded Joints

    NASA Technical Reports Server (NTRS)

    Nayeb-Hashemi, Hamid; Rossettos, J. N.

    1997-01-01

    The final report consists of 5 published papers in referred journals and a technical letter to the technical monitor. These papers include the following: (1) Comparison of the effects of debonds and voids in adhesive; (2) On the peak shear stresses in adhesive joints with voids; (3) Nondestructive evaluation of adhesively bonded joints by acousto-ultrasonic technique and acoustic emission; (4) Multiaxial fatigue life evaluation of tubular adhesively bonded joints; (5) Theoretical and experimental evaluation of the bond strength under peeling loads. The letter outlines the progress of the research. Also included is preliminary information on the study of nondestructive evaluation of composite materials subjected to localized heat damage. The investigators studied the effects of localized heat on unidirectional fiber glass epoxy composite panels. Specimens of the fiber glass epoxy composites were subjected to 400 C heat for varying lengths of time. The specimens were subjected to nondestructive tests. The specimens were then pulled to their failure and acoustic emission of these specimens were measured. The analysis of the data was continuing as of the writing of the letter, and includes a finite element stress analysis of the problem.

  16. Wetting and phase separation in soft adhesion

    NASA Astrophysics Data System (ADS)

    Jensen, Katharine; Dufresne, Eric

    2015-11-01

    In the classic theories of solid adhesion, surface energies drive deformation to increase contact area while bulk elasticity opposes it. However, recently solid surface tension has also been shown to play an important role in resisting deformation in soft materials. We explore the consequences for the physics of adhesive contact by performing experiments bringing small, rigid spheres into contact with compliant silicone gel substrates. We measure the quasi-static deformation of the substrate, particularly focusing on its structure near the contact line. In order to satisfy the wetting condition prescribed by surface tension balance while avoiding an elastic singularity at the contact line, we find that the gels undergo an adhesion-induced phase separation. This creates a four-phase contact zone with two additional, hidden contact lines. Our results indicate that accurate theories of adhesion of soft gels need to account both for the compressibility of the gel elastic network and for a non-zero surface stress between the gel and its solvent.

  17. Towards a chemistry of cohesion and adhesion

    NASA Astrophysics Data System (ADS)

    Eberhart, M. E.; Donovan, M. M.; MacLaren, J. M.; Clougherty, D. P.

    Modern chemistry frequently describes the structure and reaction dynamics of molecules in terms of the general principle of “competition for bonds”; consequently, bonding forms the basis of the language of chemistry. The actual models used to represent these bonds are frequently system specific. Organic reactions are described in terms of bonds based on pairs of atomic valence electrons. Reactions of inorganic coordination complexes are described in terms of bonds based on a molecular orbital representation. In analogy to those chemistries, a representation for a bond and bond strength, suitable for describing the cohesive and adhesive properties of all classes of materials, is introduced. This representation proves to yield an explanation for the observed cohesive properties of a specific class of materials (cleavage in bcc metals), and it also provides a framework for exploring and analyzing the more complex phenomena of cohesion and adhesion, such as environmentally-induced embrittlement. A complete chemistry of cohesion and adhesion will require the demonstration that the specific bonding model used can form the basis for consistent interpretations for a wealth of experimental phenomena beyond environmentally-induced embrittlement; thus, as presented, this model does not provide a complete chemistry of cohesion and adhesion, but does embody the first steps in that direction.

  18. Cure-rate data for silicone adhesive

    NASA Technical Reports Server (NTRS)

    Clatterbuck, C.; Fisher, A.

    1978-01-01

    Report describes work with concentrations down to 0.07 percent and is useful when applying adhesives in terrestrial and space applications. Cured Silicone retains low-outgassing properties as well as its snap, elongation, and resilience. Tests for hardness of silicone material also showed good results. No gross hysteresis observable on recovery from stretching nor was there any decrease in hardness.

  19. Non-equilibrium Silk Fibroin Adhesives

    PubMed Central

    Yucel, Tuna; Kojic, Nikola; Leisk, Gary G.; Lo, Tim J.; Kaplan, David L.

    2009-01-01

    Regenerated silkworm silk solutions formed metastable, soft-solid-like materials (e-gels) under weak electric fields, displaying interesting mechanical characteristics such as dynamic adhesion and strain stiffening. Raman spectroscopy, in situ electric field dynamic oscillatory rheology and polarized optical microscopy indicated that silk fibroin electrogelation involved intermolecular self-assembly of silk molecules into amorphous, micron-scale, micellar structures and the formation of relatively long lifetime, intermicellar entanglement crosslinks. Overall, the electrogelation process did not require significant intramolecular β-strand or intermolecular β-sheet formation, unlike silk hydrogels. The kinetics of e-gel formation could be tuned by changing the field strength and assembly conditions, such as silk concentration and solution pH, while e-gel stiffness was partially reversible by removal of the applied field. Transient adhesion testing indicated that the adhesive characteristics of e-gels could at least partially be attributed to a local increase in proton concentration around the positive electrode due to the applied field and surface effects. A working model of electrogelation was described en route to understanding the origins of the adhesive characteristics. PMID:20026216

  20. Microfabricated adhesive mimicking gecko foot-hair

    NASA Astrophysics Data System (ADS)

    Geim, A. K.; Dubonos, S. V.; Grigorieva, I. V.; Novoselov, K. S.; Zhukov, A. A.; Shapoval, S. Yu.

    2003-07-01

    The amazing climbing ability of geckos has attracted the interest of philosophers and scientists alike for centuries. However, only in the past few years has progress been made in understanding the mechanism behind this ability, which relies on submicrometre keratin hairs covering the soles of geckos. Each hair produces a miniscule force ~10-7 N (due to van der Waals and/or capillary interactions) but millions of hairs acting together create a formidable adhesion of ~10 N cm-2: sufficient to keep geckos firmly on their feet, even when upside down on a glass ceiling. It is very tempting to create a new type of adhesive by mimicking the gecko mechanism. Here we report on a prototype of such 'gecko tape' made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion. Our approach shows a way to manufacture self-cleaning, re-attachable dry adhesives, although problems related to their durability and mass production are yet to be resolved.

  1. Adhesive contact of randomly rough surfaces

    NASA Astrophysics Data System (ADS)

    Pastewka, Lars; Robbins, Mark

    2012-02-01

    The contact area, stiffness and adhesion between rigid, randomly rough surfaces and elastic substrates is studied using molecular statics and continuum simulations. The surfaces are self-affine with Hurst exponent 0.3 to 0.8 and different short λs and long λL wavelength cutoffs. The rms surface slope and the range and strength of the adhesive potential are also varied. For parameters typical of most solids, the effect of adhesion decreases as the ratio λL/λs increases. In particular, the pull-off force decreases to zero and the area of contact Ac becomes linear in the applied load L. A simple scaling argument is developed that describes the increase in the ratio Ac/L with increasing adhesion and a corresponding increase in the contact stiffness [1]. The argument also predicts a crossover to finite contact area at zero load when surfaces are exceptionally smooth or the ratio of surface tension to bulk modulus is unusually large, as for elastomers. Results that test this prediction will be presented and related to the Maugis-Dugdale [2] theories for individual asperities and the more recent scaling theory of Persson [3]. [1] Akarapu, Sharp, Robbins, Phys. Rev. Lett. 106, 204301 (2011) [2] Maugis, J. Colloid Interface Sci. 150, 243 (1992) [3] Persson, Phys. Rev. Lett. 74, 75420 (2006)

  2. Si/Cu Interface Structure and Adhesion

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Smith, John

    2006-03-01

    An ab initio investigation of the Si(111)/Cu(111) interfacial atomic structure and adhesion is reported [1]. Misfit dislocations appear naturally, as do hcp interfacial silicide phases that vary with temperature. The silicides form in the interface even at relatively low temperatures. These results are consistent with available experimental data. [1] Xiao-Gang Wang, John Smith, Physical Review Letters 95, 156102 (2005).

  3. Adhesion of D. discoideum on Hydrophobic Substrate

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Ploscariu, Nicoleta

    2015-03-01

    Adhesion by amoeboid cells, such as D. discoideum, is poorly understood but critical for other behaviors such as phagocytosis and migration. Furthermore, both leucocytes and breast cancer cells employ the amoeboid mode of movement at various points in their life-cycles. Hence, improved knowledge of amoeboid adhesion may lead to be new strategies for controlling other important cellular processes. This study regards adhesion by D. discoideum on silanized glass substrates. Reflection interference contrast microscopy is used in conjunction with other methods to determine the contact angle, cell-medium interfacial energy, and adhesion energy of these cells. The contact angle of individual cells settling under gravity onto a substrate is observed to increase as the size of the contact patch increases. This behavior occurs on slower time-scales than expected for the settling of inert vesicles. The implications of this observation on the nature of the underlying forces will be discussed. This work was supported in part by NSF Grant PHY-646966.

  4. Method for making adhesive from biomass

    DOEpatents

    Russell, Janet A.; Riemath, William F.

    1985-01-01

    A method is described for making adhesive from biomass. A liquefaction oil is prepared from lignin-bearing plant material and a phenolic fraction is extracted therefrom. The phenolic fraction is reacted with formaldehyde to yield a phenol-formaldehyde resin.

  5. Method for making adhesive from biomass

    DOEpatents

    Russell, J.A.; Riemath, W.F.

    1984-03-30

    A method is described for making adhesive from biomass. A liquefaction oil is prepared from lignin-bearing plant material and a phenolic fraction is extracted therefrom. The phenolic fraction is reacted with formaldehyde to yield a phenol-formaldehyde resin. 2 figures.

  6. Microfabricated adhesive mimicking gecko foot-hair.

    PubMed

    Geim, A K; Dubonos, S V; Grigorieva, I V; Novoselov, K S; Zhukov, A A; Shapoval, S Yu

    2003-07-01

    The amazing climbing ability of geckos has attracted the interest of philosophers and scientists alike for centuries. However, only in the past few years has progress been made in understanding the mechanism behind this ability, which relies on submicrometre keratin hairs covering the soles of geckos. Each hair produces a miniscule force approximately 10(-7) N (due to van der Waals and/or capillary interactions) but millions of hairs acting together create a formidable adhesion of approximately 10 N x cm(-2): sufficient to keep geckos firmly on their feet, even when upside down on a glass ceiling. It is very tempting to create a new type of adhesive by mimicking the gecko mechanism. Here we report on a prototype of such 'gecko tape' made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion. Our approach shows a way to manufacture self-cleaning, re-attachable dry adhesives, although problems related to their durability and mass production are yet to be resolved.

  7. Guest editorial, special issue on biobased adhesives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article is a preface for a special issue that showcases significant developments on adhesives made with biorenewable materials, such as agricultural crops (soybean, corn), plant extractives (bark, tannins), and marine sources (mussels). This collection of pioneering studies and reviews on bioba...

  8. Microfabricated adhesive mimicking gecko foot-hair.

    PubMed

    Geim, A K; Dubonos, S V; Grigorieva, I V; Novoselov, K S; Zhukov, A A; Shapoval, S Yu

    2003-07-01

    The amazing climbing ability of geckos has attracted the interest of philosophers and scientists alike for centuries. However, only in the past few years has progress been made in understanding the mechanism behind this ability, which relies on submicrometre keratin hairs covering the soles of geckos. Each hair produces a miniscule force approximately 10(-7) N (due to van der Waals and/or capillary interactions) but millions of hairs acting together create a formidable adhesion of approximately 10 N x cm(-2): sufficient to keep geckos firmly on their feet, even when upside down on a glass ceiling. It is very tempting to create a new type of adhesive by mimicking the gecko mechanism. Here we report on a prototype of such 'gecko tape' made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion. Our approach shows a way to manufacture self-cleaning, re-attachable dry adhesives, although problems related to their durability and mass production are yet to be resolved. PMID:12776092

  9. Underwater Adhesives Retrofit Pipelines with Advanced Sensors

    NASA Technical Reports Server (NTRS)

    2015-01-01

    Houston-based Astro Technology Inc. used a partnership with Johnson Space Center to pioneer an advanced fiber-optic monitoring system for offshore oil pipelines. The company's underwater adhesives allow it to retrofit older deepwater systems in order to measure pressure, temperature, strain, and flow properties, giving energy companies crucial data in real time and significantly decreasing the risk of a catastrophe.

  10. The role of material properties in adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When two solid surfaces are brought into contact strong adhesive bond forces can develop between the materials. The magnitude of the forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between solids is addressed from a theoretical consideration of the electronic nature of the surfaces and experimentally relating bond forces to the nature of the interface resulting from solid state contact. Surface properties correlated with adhesion include, atomic or molecular orientation, reconstruction and segregation as well as the chemistry of the surface specie. Where dissimilar solids are in contact the contribution of each is considered as is the role of their interactive chemistry on bond strength. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structure, crystallographic orientation and state. Materials examined with respect to interfacial adhesive interactions include metals, alloys, ceramics, polymers and diamond. They are reviewed both in single and polycrystalline form. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  11. Nitrogen starvation affects bacterial adhesion to soil

    PubMed Central

    Borges, Maria Tereza; Nascimento, Antônio Galvão; Rocha, Ulisses Nunes; Tótola, Marcos Rogério

    2008-01-01

    One of the main factors limiting the bioremediation of subsoil environments based on bioaugmentation is the transport of selected microorganisms to the contaminated zones. The characterization of the physiological responses of the inoculated microorganisms to starvation, especially the evaluation of characteristics that affect the adhesion of the cells to soil particles, is fundamental to anticipate the success or failure of bioaugmentation. The objective of this study was to investigate the effect of nitrogen starvation on cell surface hydrophobicity and cell adhesion to soil particles by bacterial strains previously characterized as able to use benzene, toluene or xilenes as carbon and energy sources. The strains LBBMA 18-T (non-identified), Arthrobacter aurescens LBBMA 98, Arthrobacter oxydans LBBMA 201, and Klebsiella sp. LBBMA 204–1 were used in the experiments. Cultivation of the cells in nitrogen-deficient medium caused a significant reduction of the adhesion to soil particles by all the four strains. Nitrogen starvation also reduced significantly the strength of cell adhesion to the soil particles, except for Klebsiella sp. LBBMA 204–1. Two of the four strains showed significant reduction in cell surface hydrophobicity. It is inferred that the efficiency of bacterial transport through soils might be potentially increased by nitrogen starvation. PMID:24031246

  12. Performance of thermal adhesives in forced convection

    NASA Technical Reports Server (NTRS)

    Kundu, Nikhil K.

    1993-01-01

    Cooling is critical for the life and performance of electronic equipment. In most cases cooling may be achieved by natural convection but forced convection may be necessary for high wattage applications. Use of conventional type heat sinks may not be feasible from the viewpoint of specific applications and the costs involved. In a heat sink, fins can be attached to the well by ultrasonic welding, by soldering, or with a number of industrially available thermal adhesives. In this paper, the author investigates the heat transfer characteristics of several adhesives and compares them with ultrasonic welding and theoretically calculated values. This experiment was conducted in an air flow chamber. Heat was generated by using heaters mounted on the well. Thermstrate foil, Uniset A401, and Aremco 571 adhesives were tested along with an ultrasonically welded sample. Ultrasonic welding performed far better than the adhesives and Thermstrate foil. This type of experiment can be adapted for a laboratory exercise in an upper level heat transfer course. It gives students an exposure to industrial applications that help them appreciate the importance of the course material.

  13. Adhesive Bioactive Coatings Inspired by Sea Life.

    PubMed

    Rego, Sónia J; Vale, Ana C; Luz, Gisela M; Mano, João F; Alves, Natália M

    2016-01-19

    Inspired by nature, in particular by the marine mussels adhesive proteins (MAPs) and by the tough brick-and-mortar nacre-like structure, novel multilayered films are prepared in the present work. Organic-inorganic multilayered films, with an architecture similar to nacre based on bioactive glass nanoparticles (BG), chitosan, and hyaluronic acid modified with catechol groups, which are the main components responsible for the outstanding adhesion in MAPs, are developed for the first time. The biomimetic conjugate is prepared by carbodiimide chemistry and analyzed by ultraviolet-visible spectrophotometry. The buildup of the multilayered films is monitored with a quartz crystal microbalance with dissipation monitoring, and their topography is characterized by atomic force microscopy. The mechanical properties reveal that the films containing catechol groups and BG present an enhanced adhesion. Moreover, the bioactivity of the films upon immersion in a simulated body fluid solution is evaluated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. It was found that the constructed films promote the formation of bonelike apatite in vitro. Such multifunctional mussel inspired LbL films, which combine enhanced adhesion and bioactivity, could be potentially used as coatings of a variety of implants for orthopedic applications. PMID:26653103

  14. Flowmeter determines mix ratio for viscous adhesives

    NASA Technical Reports Server (NTRS)

    Lemons, C. R.

    1967-01-01

    Flowmeter determines mix ratio for continuous flow mixing machine used to produce an adhesive from a high viscosity resin and aliphatic amine hardener pumped through separate lines to a rotary blender. The flowmeter uses strain gages in the two flow paths and monitors their outputs with appropriate instrumentation.

  15. The evolution of adhesiveness as a social adaptation.

    PubMed

    Garcia, Thomas; Doulcier, Guilhem; De Monte, Silvia

    2015-11-27

    Cellular adhesion is a key ingredient to sustain collective functions of microbial aggregates. Here, we investigate the evolutionary origins of adhesion and the emergence of groups of genealogically unrelated cells with a game-theoretical model. The considered adhesiveness trait is costly, continuous and affects both group formation and group-derived benefits. The formalism of adaptive dynamics reveals two evolutionary stable strategies, at each extreme on the axis of adhesiveness. We show that cohesive groups can evolve by small mutational steps, provided the population is already endowed with a minimum adhesiveness level. Assortment between more adhesive types, and in particular differential propensities to leave a fraction of individuals ungrouped at the end of the aggregation process, can compensate for the cost of increased adhesiveness. We also discuss the change in the social nature of more adhesive mutations along evolutionary trajectories, and find that altruism arises before directly beneficial behavior, despite being the most challenging form of cooperation.

  16. Current pharmaceutical design on adhesive based transdermal drug delivery systems.

    PubMed

    Ghosh, Animesh; Banerjee, Subham; Kaity, Santanu; Wong, Tin W

    2015-01-01

    Drug-in-adhesive transdermal drug delivery matrix exploits intimate contact of the carrier with stratum corneum, the principal skin barrier to drug transport, to deliver the actives across the skin and into the systemic circulation. The main application challenges of drug-in-adhesive matrix lie in the physicochemical properties of skin varying with age, gender, ethnicity, health and environmental condition of patients. This in turn poses difficulty to design a universal formulation to meet the intended adhesiveness, drug release and drug permeation performances. This review focuses on pressure-sensitive adhesives, and their adhesiveness and drug release/permeation modulation mechanisms as a function of adhesive molecular structure and formulation attributes. It discusses approaches to modulate adhesive tackiness, strength, elasticity, hydrophilicity, molecular suspension capability and swelling capacity, which contribute to the net effect of adhesive on skin bonding, drug release and drug permeation. PMID:25925119

  17. Current pharmaceutical design on adhesive based transdermal drug delivery systems.

    PubMed

    Ghosh, Animesh; Banerjee, Subham; Kaity, Santanu; Wong, Tin W

    2015-01-01

    Drug-in-adhesive transdermal drug delivery matrix exploits intimate contact of the carrier with stratum corneum, the principal skin barrier to drug transport, to deliver the actives across the skin and into the systemic circulation. The main application challenges of drug-in-adhesive matrix lie in the physicochemical properties of skin varying with age, gender, ethnicity, health and environmental condition of patients. This in turn poses difficulty to design a universal formulation to meet the intended adhesiveness, drug release and drug permeation performances. This review focuses on pressure-sensitive adhesives, and their adhesiveness and drug release/permeation modulation mechanisms as a function of adhesive molecular structure and formulation attributes. It discusses approaches to modulate adhesive tackiness, strength, elasticity, hydrophilicity, molecular suspension capability and swelling capacity, which contribute to the net effect of adhesive on skin bonding, drug release and drug permeation.

  18. Piezoelectric inkjet printing of medical adhesives and sealants

    NASA Astrophysics Data System (ADS)

    Boehm, Ryan D.; Gittard, Shaun D.; Byrne, Jacqueline M. H.; Doraiswamy, Anand; Wilker, Jonathan J.; Dunaway, Timothy M.; Crombez, Rene; Shen, Weidian; Lee, Yuan-Shin; Narayan, Roger J.

    2010-07-01

    Piezoelectric inkjet printing is a noncontact process that enables microscale processing of biological materials. In this research summary, the use of piezoelectric inkjet printing for patterning medical adhesives and sealants, including a two-component polyethylene glycol hydrogel-based medical sealant, an N-butyl cyanoacrylate tissue adhesive, and a mussel adhesive protein biological adhesive, is described The effect of Fe(III) on mussel adhesive protein structure was evaluated by means of atomic force microscopy. The ability to process microscale patterns of medical sealants and adhesives will provide an improvement in tissue joining, including enhanced tissue integrity, reduced bond lines, and decreased adhesive toxicity. Piezoelectric inkjet deposition of medical adhesives and sealants may be used in wound closure, fracture fixation, and microscale vascular surgery.

  19. Environmental and viscoelastic effects on stresses in adhesive joints

    SciTech Connect

    Palazotto, A.N.; Birman, V.

    1995-04-01

    This paper considers the state of the art in several important areas of research on adhesively bonded joints. The paper reviews the studies dealing with environmental and viscoelastic effects on stresses in adhesive joints. Environmental factors that affect stresses include temperature and moisture. These factors are analyzed and practical examples that illustrate their impact on adhesives are given for the solid-rocket motor, which is a structural component paramount to the U.S. space program. The paper deals with viscoelastic effects on adhesive joints, and a number of viscoelastic models used in the analysis of viscoelastic materials, including adhesives, are reviewed. The use of the solid-rocket motor as an example characterizes the circumstances where viscoelastic properties of adhesive layers are essential. Close attention is paid to the fractional derivative model of Bagley and Torvik, which may be a good candidate for an analytical study of adhesive joints. Finally, existing studies on viscoelastic adhesive joints are considered. 54 refs.

  20. Strong, reversible underwater adhesion via gecko-inspired hydrophobic fibers.

    PubMed

    Soltannia, Babak; Sameoto, Dan

    2014-12-24

    Strong, reversible underwater adhesion using gecko-inspired surfaces is achievable through the use of a hydrophobic structural material and does not require surface modification or suction cup effects for this adhesion to be effective. Increased surface energy can aid in dry adhesion in an air environment but strongly degrades wet adhesion via reduction of interfacial energy underwater. A direct comparison of structurally identical but chemically different mushroom shaped fibers shows that strong, reversible adhesion, even in a fully wetted, stable state, is feasible underwater if the structural material of the fibers is hydrophobic and the mating surface is not strongly hydrophilic. The exact adhesion strength will be a function of the underwater interfacial energy between surfaces and the specific failure modes of individual fibers. This underwater adhesion has been calculated to be potentially greater than the dry adhesion for specific combinations of hydrophobic surfaces.

  1. Evaluation of the micro-shear bond strength of four adhesive systems to dentin with and without adhesive area limitation.

    PubMed

    Chai, Yuan; Lin, Hong; Zheng, Gang; Zhang, Xuehui; Niu, Guangliang; Du, Qiao

    2015-01-01

    The purpose of this study was to evaluate the bonding ability of four representative dentin-adhesive systems by applying the micro-shear bond strength (μ-SBS) test method and to evaluate the influence of adhesive area limitation on the bond strength. Two different adhesive application methods were used in the μ-SBS test (with and without adhesives area limitation), and four representative adhesive systems were used in this study. Each dentin surface was treated with one of the four representative adhesive systems, and with twenty samples per group (n=20), each of the four groups underwent a μ-SBS test. The results showed that the bond strength was significantly influenced by the adhesive application method (p<0.05), the adhesive type (p<0.05) and the interaction between the two factors (p<0.05). With regard to the four representative dentin-adhesive systems, 3-E&R has a much better bond quality compared to the other adhesive systems. Furthermore, the micro-shear bond strength test method of restricting the area of both the adhesive and the resin is more reliable for evaluating the bonding property of adhesives to dentin, and it is also adequate for comparing the different adhesives systems. PMID:26406058

  2. Adhesive small bowel adhesions obstruction: Evolutions in diagnosis, management and prevention

    PubMed Central

    Catena, Fausto; Di Saverio, Salomone; Coccolini, Federico; Ansaloni, Luca; De Simone, Belinda; Sartelli, Massimo; Van Goor, Harry

    2016-01-01

    Intra-abdominal adhesions following abdominal surgery represent a major unsolved problem. They are the first cause of small bowel obstruction. Diagnosis is based on clinical evaluation, water-soluble contrast follow-through and computed tomography scan. For patients presenting no signs of strangulation, peritonitis or severe intestinal impairment there is good evidence to support non-operative management. Open surgery is the preferred method for the surgical treatment of adhesive small bowel obstruction, in case of suspected strangulation or after failed conservative management, but laparoscopy is gaining widespread acceptance especially in selected group of patients. "Good" surgical technique and anti-adhesive barriers are the main current concepts of adhesion prevention. We discuss current knowledge in modern diagnosis and evolving strategies for management and prevention that are leading to stratified care for patients. PMID:27022449

  3. TOPICAL REVIEW: Recent advances in the fabrication and adhesion testing of biomimetic dry adhesives

    NASA Astrophysics Data System (ADS)

    Sameoto, D.; Menon, C.

    2010-10-01

    In the past two years, there have been a large number of publications on the topic of biomimetic dry adhesives from modeling, fabrication and testing perspectives. We review and compare the most recent advances in fabrication and testing of these materials. While there is increased convergence and consensus as to what makes a good dry adhesive, the fabrication of these materials is still challenging, particularly for anisotropic or hierarchal designs. Although qualitative comparisons between different adhesive designs can be made, quantifying the exact performance and rating each design is significantly hampered by the lack of standardized testing methods. Manufacturing dry adhesives, which can reliably adhere to rough surfaces, show directional and self-cleaning behavior and are relatively simple to manufacture, is still very challenging—great strides by multiple research groups have however made these goals appear achievable within the next few years.

  4. Measurement of surface adhesion force of adhesion promoter and release layer for UV-nanoimprint lithography.

    PubMed

    Choi, Dae-Geun; Lee, Dong-Il; Kim, Ki-Don; Jeong, Jun-Ho; Choi, Jun-Hyuk; Lee, Eung-Sug

    2009-02-01

    In this work, we investigated the effect of surface treatment as release layer and adhesion promoter for UV-Nanoimprint lithography and measured the surface adhesion force by using tensile separation force of Instron equipment. Several Self-Assembled Monolayers (SAMs) of 3-Acryloxypropyl methyl dichlorosilane (APMDS) 3-Aminopropyl-triethoxysilane (APTS), and 3-Glycidoxypropyltrimethoxysilane (GPTS) as adhesion promoters and (1H,1H,2H,2H-perfluorooctyl)trichlorosilane (FOTS) as release layer were fabricated by vapor deposition method and were compared with oxygen plasma treatment. APMDS could strongly improve the adhesion force between UV-curable acrylate resin and silicon substrate because of strong covalent bonding. Finally, we could successfully fabricate various imprint patterns by using proper surface treatment of SAMs.

  5. Surface pretreatments for medical application of adhesion

    PubMed Central

    Erli, Hans J; Marx, Rudolf; Paar, Othmar; Niethard, Fritz U; Weber, Michael; Wirtz, Dieter C

    2003-01-01

    Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body. PMID:14561228

  6. Assessment of piezoelectric sensor adhesive bonding

    NASA Astrophysics Data System (ADS)

    Wandowski, T.; Moll, J.; Malinowski, P.; Opoka, S.; Ostachowicz, W.

    2015-07-01

    Piezoelectric transducers are widely utilized in Structural Health Monitoring (SHM). They are used both in guided wave-based and electromechanical impedance-based methods. Transducer debonding or unevenly distributed glue underneath the transducer reduce the performance and reliability of the SHM system. Therefore, quality assessment methods for glue layer need to be developed. In this paper, the authors present results obtained from two methods that allow the quality assessment of adhesive bonds of piezoelectric transducers. The electromechanical impedance method is utilized to analyze transducer adhesive bonding. An improperly prepared bonding layer is a source for changes in the electromechanical impedance characteristics in comparison to a perfectly bonded transducer. In the resistance characteristics of the properly bonded transducer the resonance peaks of the structure were clearly visible. In the case when adhesive layer is not equally distributed under sensor, the amplitudes of structural resonance peaks are reduced. In the case of completely detached transducer, the structural resonance peaks disappear and only resonance peaks of the transducer itself are visible. These peaks (peaks of free transducer hanging on wires) are significantly larger than the resonance peaks of the investigated structure in the considered frequency interval. The bonding layer shape is also analyzed using time-domain terahertz spectroscopy in reflection mode. This method allows to visualize the adhesive layer distribution based on C-scan analysis. C-scans of signals or envelope-detected signals can be used to estimate the area of proper adhesion between bonding agent and transducer and hence provides a more quantitative approach towards transducer inspection.

  7. An adhesive protein capsule of Escherichia coli.

    PubMed Central

    Orskov, I; Birch-Andersen, A; Duguid, J P; Stenderup, J; Orskov, F

    1985-01-01

    The nature of the adhesive capacity of three hemagglutinating Escherichia coli strains that had earlier been described as nonfimbriated was studied. The strains that were isolated from human disease adhered to human buccal and urinary tract epithelial cells, an adhesion that was not inhibited by D-mannose. By crossed immunoelectrophoresis it was shown that the three strains produced a common antigen, Z1, developed after growth at 37 degrees C but not 18 degrees C. One of the strains produced an additional antigen, Z2, of almost the same electrophoretic mobility in crossed immunoelectrophoresis. A mutant of this strain deficient of its polysaccharide K antigen had maintained the adhesive capacity, indicating that the K antigen was not responsible for adhesion. A further mutant of the acapsular mutant produced a strongly reduced amount of the Z antigens and had lost the ability to adhere. The Z1 (and Z2?) antigens were therefore deemed to be responsible for adhesion. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis of extracts of cells of the three strains, a heavy Coomassie-blue stained line was seen, indicating the presence of a protein subunit of molecular weight slightly above 14,400. By immunoblotting with absorbed antiserum, it was shown that this protein was the same as that detected by crossed immunoelectrophoresis. Protease from Streptomyces griseus, but not trypsin, digested the protein. Heating to 100 degrees C did not affect it. By immunoelectron microscopy of embedded and sectioned bacteria that had first been treated with specific antisera and ferritin-labeled antirabbit immunoglobulin, the protein adhesin-antibody complex was found to surround the bacteria as a heavy capsule. After negative staining with uranylacetate (pH approximately 4), the capsule appeared as a mesh of very fine filaments. The possible role of this capsule in the pathogenesis of disease is discussed. Images PMID:2856913

  8. Extreme positive allometry of animal adhesive pads and the size limits of adhesion-based climbing

    PubMed Central

    Labonte, David; Clemente, Christofer J.; Dittrich, Alex; Kuo, Chi-Yun; Crosby, Alfred J.; Irschick, Duncan J.; Federle, Walter

    2016-01-01

    Organismal functions are size-dependent whenever body surfaces supply body volumes. Larger organisms can develop strongly folded internal surfaces for enhanced diffusion, but in many cases areas cannot be folded so that their enlargement is constrained by anatomy, presenting a problem for larger animals. Here, we study the allometry of adhesive pad area in 225 climbing animal species, covering more than seven orders of magnitude in weight. Across all taxa, adhesive pad area showed extreme positive allometry and scaled with weight, implying a 200-fold increase of relative pad area from mites to geckos. However, allometric scaling coefficients for pad area systematically decreased with taxonomic level and were close to isometry when evolutionary history was accounted for, indicating that the substantial anatomical changes required to achieve this increase in relative pad area are limited by phylogenetic constraints. Using a comparative phylogenetic approach, we found that the departure from isometry is almost exclusively caused by large differences in size-corrected pad area between arthropods and vertebrates. To mitigate the expected decrease of weight-specific adhesion within closely related taxa where pad area scaled close to isometry, data for several taxa suggest that the pads’ adhesive strength increased for larger animals. The combination of adjustments in relative pad area for distantly related taxa and changes in adhesive strength for closely related groups helps explain how climbing with adhesive pads has evolved in animals varying over seven orders of magnitude in body weight. Our results illustrate the size limits of adhesion-based climbing, with profound implications for large-scale bio-inspired adhesives. PMID:26787862

  9. Alterations in Adhesion, Transport, and Membrane Characteristics in an Adhesion-Deficient Pseudomonad

    PubMed Central

    DeFlaun, M. F.; Oppenheimer, S. R.; Streger, S.; Condee, C. W.; Fletcher, M.

    1999-01-01

    A stable adhesion-deficient mutant of Burkholderia cepacia G4, a soil pseudomonad, was selected in a sand column assay. This mutant (ENV435) was compared to the wild-type strain by examining the adhesion of the organisms to silica sand and their transport through two aquifer sediments that differed in their sand, silt, and clay contents. We compared the longitudinal transport of the wild type and the adhesion mutant to the transport of a conservative chloride tracer in 25-cm-long glass columns. The transport of the wild-type strain was severely retarded compared to the transport of the conservative tracer in a variety of aquifer sediments, while the adhesion mutant and the conservative tracer traveled at similar rates. An intact sediment core study produced similar results; ENV435 was transported at a faster rate and in much greater numbers than G4. The results of hydrophobic interaction chromatography revealed that G4 was significantly more hydrophobic than ENV435, and polyacrylamide gel electrophoresis revealed significant differences in the lipopolysaccharide O-antigens of the adhesion mutant and the wild type. Differences in this cell surface polymer may explain the decreased adhesion of strain ENV435. PMID:9925613

  10. Rheology and adhesion of poly(acrylic acid)/laponite nanocomposite hydrogels as biocompatible adhesives.

    PubMed

    Shen, Muxian; Li, Li; Sun, Yimin; Xu, Jun; Guo, Xuhong; Prud'homme, Robert K

    2014-02-18

    Biocompatible nanocomposite hydrogels (NC gels) consisting of poly(acrylic acid) (PAA) and nanosized clay (Laponite) were successfully synthesized by in situ free-radical polymerization of acrylic acid (AA) in aqueous solutions of Laponite. The obtained NC gels were uniform and transparent. Their viscosity, storage modulus G', and loss modulus G″ increased significantly upon increasing the content of Laponite and the dose of AA, while exhibiting a maximum with increasing the neutralization degree of AA. They showed tunable adhesion by changing the dose of Laponite and monomer as well as the neutralization degree of AA, as determined by 180° peel strength measurement. The maximal adhesion was shown when reaching a balance between cohesion and fluidity. A homemade Johnson-Kendall-Roberts (JKR) instrument was employed to study the surface adhesion behavior of the NC gels. The combination of peel strength, rheology, and JKR measurements offers the opportunity of insight into the mechanism of adhesion of hydrogels. The NC gels with tunable adhesion should be ideal candidates for dental adhesive, wound dressing, and tissue engineering. PMID:24460239

  11. Hierarchical macroscopic fibrillar adhesives: in situ study of buckling and adhesion mechanisms on wavy substrates.

    PubMed

    Bauer, Christina T; Kroner, Elmar; Fleck, Norman A; Arzt, Eduard

    2015-10-23

    Nature uses hierarchical fibrillar structures to mediate temporary adhesion to arbitrary substrates. Such structures provide high compliance such that the flat fibril tips can be better positioned with respect to asperities of a wavy rough substrate. We investigated the buckling and adhesion of hierarchically structured adhesives in contact with flat smooth, flat rough and wavy rough substrates. A macroscopic model for the structural adhesive was fabricated by molding polydimethylsiloxane into pillars of diameter in the range of 0.3-4.8 mm, with up to three different hierarchy levels. Both flat-ended and mushroom-shaped hierarchical samples buckled at preloads one quarter that of the single level structures. We explain this behavior by a change in the buckling mode; buckling leads to a loss of contact and diminishes adhesion. Our results indicate that hierarchical structures can have a strong influence on the degree of adhesion on both flat and wavy substrates. Strategies are discussed that achieve highly compliant substrates which adhere to rough substrates.

  12. Polymer adhesion at surfaces: biological adhesive proteins and their synthetic mimics

    NASA Astrophysics Data System (ADS)

    Messersmith, Phillip

    2008-03-01

    Mussels are famous for their ability to permanently adhere to a wide variety of wet surfaces, such as rocks, metal and polymer ship hulls, and wood structures. They accomplish this through specialized proteins collectively referred to as mussel adhesive proteins (MAPs). The biophysical aspects of MAP adhesion is being revealed through the use of single molecule force measurements. The results provide insight into the adhesive roles of key amino acids found in these proteins, including the magnitude of adhesive forces, cooperative effects, and their self-healing properties. This molecular-level information is being incorporated into designs of biomimetic polymer coatings for a variety of applications. Our biomimetic approach to polymer design will be illustrated by a few examples where adhesive constituents found in MAPs are exploited to make wet-adhesive polymer coatings. In addition, small molecule analogs of MAPs can be used to apply thin functional films onto virtually any material surface using a facile approach. These coatings have a variety of potential uses in microelectronics, water treatment, prevention of environmental biofouling, and for control of biointerfacial phenomena at the surfaces of medical/diagnostic devices.

  13. The Talin Head Domain Reinforces Integrin-Mediated Adhesion by Promoting Adhesion Complex Stability and Clustering

    PubMed Central

    Ellis, Stephanie J.; Lostchuck, Emily; Goult, Benjamin T.; Bouaouina, Mohamed; Fairchild, Michael J.; López-Ceballos, Pablo; Calderwood, David A.; Tanentzapf, Guy

    2014-01-01

    Talin serves an essential function during integrin-mediated adhesion in linking integrins to actin via the intracellular adhesion complex. In addition, the N-terminal head domain of talin regulates the affinity of integrins for their ECM-ligands, a process known as inside-out activation. We previously showed that in Drosophila, mutating the integrin binding site in the talin head domain resulted in weakened adhesion to the ECM. Intriguingly, subsequent studies showed that canonical inside-out activation of integrin might not take place in flies. Consistent with this, a mutation in talin that specifically blocks its ability to activate mammalian integrins does not significantly impinge on talin function during fly development. Here, we describe results suggesting that the talin head domain reinforces and stabilizes the integrin adhesion complex by promoting integrin clustering distinct from its ability to support inside-out activation. Specifically, we show that an allele of talin containing a mutation that disrupts intramolecular interactions within the talin head attenuates the assembly and reinforcement of the integrin adhesion complex. Importantly, we provide evidence that this mutation blocks integrin clustering in vivo. We propose that the talin head domain is essential for regulating integrin avidity in Drosophila and that this is crucial for integrin-mediated adhesion during animal development. PMID:25393120

  14. Rapid Development of Wet Adhesion between Carboxymethylcellulose Modified Cellulose Surfaces Laminated with Polyvinylamine Adhesive.

    PubMed

    Gustafsson, Emil; Pelton, Robert; Wågberg, Lars

    2016-09-14

    The surface of regenerated cellulose membranes was modified by irreversible adsorption of carboxymethylcellulose (CMC). Pairs of wet CMC-modified membranes were laminated with polyvinylamine (PVAm) at room temperature, and the delamination force for wet membranes was measured for both dried and never-dried laminates. The wet adhesion was studied as a function of PVAm molecular weight, amine content, and deposition pH of the polyelectrolyte. Surprisingly the PVAm-CMC system gave substantial wet adhesion that exceeded that of TEMPO-oxidized membranes with PVAm for both dried and never-dried laminates. The greatest wet adhesion was achieved for fully hydrolyzed high molecular weight PVAm. Bulk carboxymethylation of cellulose membranes gave inferior wet adhesion combined with PVAm as compared to CMC adsorption which indicates that a CMC layer of the order of 10 nm was necessary. There are no obvious covalent cross-linking reactions between CMC and PVAm at room temperature, and on the basis of our results, we are instead attributing the wet adhesion to complex formation between the PVAm and the irreversibly adsorbed CMC at the cellulose surface. We propose that interdigitation of PVAm chains into the CMC layer is responsible for the high wet adhesion values. PMID:27552256

  15. Intercellular adhesion molecule 1 is the major adhesion molecule expressed during schistosome granuloma formation.

    PubMed Central

    Ritter, D M; McKerrow, J H

    1996-01-01

    Endothelial cell adhesion molecules play a key role in inflammation by initiating leukocyte trafficking. One of the most complex inflammatory responses is the formation of a cellular granuloma. Expression of adhesion molecules during granuloma formation was investigated by using the murine host reaction to schistosome parasite eggs deposited in the liver as a model. By both immunohistochemistry and lymphocyte adhesion assays, the predominant interaction identified was between intercellular adhesion molecule 1 (ICAM-1) and its cognate integrin, leukocyte functional antigen 1 (LFA-1). ICAM-1 expression on sinusoidal endothelium was induced when eggs were first deposited in the liver, peaked in parallel with granuloma size, and was downregulated with modulation of the granuloma. Polyacrylamide beads coated with soluble parasite egg antigens could induce ICAM-1 expression on endothelial cells in vitro only in the presence of tumor necrosis factor alpha, a cytokine previously shown to be key to granuloma formation. A role for ICAM-1 in recruiting lymphocytes to the hepatic granuloma was also supported by the observation that lymphocytes preincubated with anti-LFA-1 antibody did not bind to granulomas in tissue sections. While ICAM-1 is the predominant adhesion molecule in schistosome egg granuloma formation in wild-type mice, when the ICAM-1 gene is knocked out, vascular cell adhesion molecule 1 is upregulated and granuloma formation is preserved. PMID:8890229

  16. Cell adhesion in zebrafish myogenesis: distribution of intermediate filaments, microfilaments, intracellular adhesion structures and extracellular matrix.

    PubMed

    Costa, Manoel L; Escaleira, Roberta C; Jazenko, Fernanda; Mermelstein, Claudia S

    2008-10-01

    To overcome the limitations of in vitro studies, we have been studying myogenesis in situ in zebrafish embryos, at a sub-cellular level. While in previous works we focused on myofibrillogenesis and some aspects of adhesion structures, here we describe in more detail cell adhesion structures and interactions among cytoskeletal components, membrane and extracellular matrix during zebrafish muscle development. We studied the intermediate filaments, and we describe the full range of desmin distribution in zebrafish development, from perinuclear to striated, until its deposition around the intersomite septa of older somites. This adhesion structure, positive for desmin and actin, has not been previously observed in myogenesis in vitro. We also show that actin is initially located in the intersomite septum region whereas it is confined to the myofibrils later on. While actin localization changes during development, the adhesion complex proteins vinculin, paxillin, talin, dystrophin, laminin and fibronectin always appear exclusively at the intersomite septa, and appear to be co-distributed, even though the extracellular proteins accumulates before the intracellular ones. Contrary to the adhesion proteins, that are continuously distributed, desmin and sarcomeric actin form triangular aggregates among the septa and the cytoskeleton. We studied the cytoskeletal linker plectin as well, and we show that it has a distribution similar to desmin and not to actin. We conclude that the in situ adhesion structures differ from their in vitro counterparts, and that the actual zebrafish embryo myogenesis is quite different than that which occurs in in vitro systems.

  17. Temperature Effects on Adhesive Bond Strengths and Modulus for Commonly Used Spacecraft Structural Adhesives

    NASA Technical Reports Server (NTRS)

    Ojeda, Cassandra E.; Oakes, Eric J.; Hill, Jennifer R.; Aldi, Dominic; Forsberg, Gustaf A.

    2011-01-01

    A study was performed to observe how changes in temperature and substrate material affected the strength and modulus of an adhesive bondline. Seven different adhesives commonly used in aerospace bonded structures were tested. Aluminum, titanium and Invar adherends were cleaned and primed, then bonded using the manufacturer's recommendations. Following surface preparation, the coupons were bonded with the adhesives. The single lap shear coupons were then pull tested per ASTM D 1002 Standard Test Method for Apparent Shear Strength of Single- Lap-Joint over a temperature range from -150 deg C up to +150 deg C. The ultimate strength was calculated and the resulting data were converted into B-basis design allowables. Average and Bbasis results were compared. Results obtained using aluminum adherends are reported. The effects of using different adherend materials and temperature were also studied and will be reported in a subsequent paper. Dynamic Mechanical Analysis (DMA) was used to study variations in adhesive modulus with temperature. This work resulted in a highly useful database for comparing adhesive performance over a wide range of temperatures, and has facilitated selection of the appropriate adhesive for spacecraft structure applications.

  18. Alterations in adhesion, transport, and membrane characteristics in an adhesion-deficient pseudomonad

    SciTech Connect

    DeFlaun, M.F.; Streger, S.; Condee, C.W.; Oppenheimer, S.R.; Fletcher, M.

    1999-02-01

    A stable adhesion-deficient mutant of Burkholderia cepacia G4, a soil pseudomonad, was selected in a sand column assay. This mutant (ENV435) was compared to the wild-type strain by examining the adhesion of the organisms to silica sand and their transport through two aquifer sediments that differed in their sand, silt, and clay contents. The authors compared the longitudinal transport of the wild type and the adhesion mutant to the transport of a conservative chloride tracer in 25-cm-long glass columns. The transport of the wild-type strain was severely retarded compared to the transport of the conservative tracer in a variety of aquifer sediments, while the adhesion mutant and the conservative tracer traveled at similar rates. An intact sediment core study produced similar results; ENV435 was transported at a faster rate and in much greater numbers than G4. The results of hydrophobic interaction chromatography revealed that G4 was significantly more hydrophobic than ENV435, and polyacrylamide gel electrophoresis revealed significant differences in the lipopolysaccharide O-antigens of the adhesion mutant and the wild type. Differences in this cell surface polymer may explain the decreased adhesion of strain ENV435.

  19. Humidity-enhanced wet adhesion on insect-inspired fibrillar adhesive pads

    PubMed Central

    Xue, Longjian; Kovalev, Alexander; Eichler-Volf, Anna; Steinhart, Martin; Gorb, Stanislav N.

    2015-01-01

    Many insect species reversibly adhere to surfaces by combining contact splitting (contact formation via fibrillar contact elements) and wet adhesion (supply of liquid secretion via pores in the insects’ feet). Here, we fabricate insect-inspired fibrillar pads for wet adhesion containing continuous pore systems through which liquid is supplied to the contact interfaces. Synergistic interaction of capillarity and humidity-induced pad softening increases the pull-off force and the work of adhesion by two orders of magnitude. This increase and the independence of pull-off force on the applied load are caused by the capillarity-supported formation of solid–solid contact between pad and the surface. Solid–solid contact dominates adhesion at high humidity and capillarity at low humidity. At low humidity, the work of adhesion strongly depends on the amount of liquid deposited on the surface and, therefore, on contact duration. These results may pave the way for the design of insect-inspired adhesive pads. PMID:25791574

  20. Soy and cottonseed protein blends as wood adhesives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As an environmentally friendlier alternative to adhesives from petroleum feedstock, soy proteins are currently being formulated as wood adhesives. Cottonseed proteins have also been found to provide good adhesive properties. In at least some cases, cottonseed proteins appear to form greater shear ...

  1. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  2. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  3. 7 CFR 3201.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Adhesive and mastic removers. 3201.16 Section 3201.16... Designated Items § 3201.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue,...

  4. 7 CFR 3201.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Adhesive and mastic removers. 3201.16 Section 3201.16... Designated Items § 3201.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue,...

  5. 7 CFR 3201.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Adhesive and mastic removers. 3201.16 Section 3201.16... Designated Items § 3201.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue,...

  6. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  7. 7 CFR 2902.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Adhesive and mastic removers. 2902.16 Section 2902.16... Items § 2902.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue, tape, and...

  8. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  9. 7 CFR 2902.16 - Adhesive and mastic removers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Adhesive and mastic removers. 2902.16 Section 2902.16... Items § 2902.16 Adhesive and mastic removers. (a) Definition. Solvent products formulated for use in removing asbestos, carpet, and tile mastics as well as adhesive materials, including glue, tape, and...

  10. 49 CFR 587.16 - Adhesive bonding procedure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Adhesive bonding procedure. 587.16 Section 587.16... Adhesive bonding procedure. Immediately before bonding, aluminum sheet surfaces to be bonded are thoroughly... the abrading process are removed, as these can adversely affect bonding. The adhesive is applied...

  11. Fabrication and characterization of hierarchical nanostructured smart adhesion surfaces.

    PubMed

    Lee, Hyungoo; Bhushan, Bharat

    2012-04-15

    The mechanics of fibrillar adhesive surfaces of biological systems such as a Lotus leaf and a gecko are widely studied due to their unique surface properties. The Lotus leaf is a model for superhydrophobic surfaces, self-cleaning properties, and low adhesion. Gecko feet have high adhesion due to the high micro/nanofibrillar hierarchical structures. A nanostructured surface may exhibit low adhesion or high adhesion depending upon fibrillar density, and it presents the possibility of realizing eco-friendly surface structures with desirable adhesion. The current research, for the first time uses a patterning technique to fabricate smart adhesion surfaces: single- and two-level hierarchical synthetic adhesive structure surfaces with various fibrillar densities and diameters that allows the observation of either the Lotus or gecko adhesion effects. Contact angles of the fabricated structured samples were measured to characterize their wettability, and contamination experiments were performed to study for self-cleaning ability. A conventional and a glass ball attached to an atomic force microscope (AFM) tip were used to obtain the adhesive forces via force-distance curves to study scale effect. A further increase of the adhesive forces on the samples was achieved by applying an adhesive to the surfaces.

  12. Mechanical properties of Hysol EA-9394 structural adhesive

    SciTech Connect

    Guess, T.R.; Reedy, E.D.; Stavig, M.E.

    1995-02-01

    Dextor`s Hysol EA-9394 is a room temperature curable paste adhesive representative of the adhesives used in wind turbine blade joints. A mechanical testing program has been performed to characterize this adhesive. Tension, compression stress relaxation, flexural, butt tensile, and fracture toughness test results are reported.

  13. Phyllostachys edulis Compounds Inhibit Palmitic Acid-Induced Monocyte Chemoattractant Protein 1 (MCP-1) Production

    PubMed Central

    Higa, Jason K.; Liang, Zhibin; Williams, Philip G.; Panee, Jun

    2012-01-01

    Background Phyllostachys edulis Carriere (Poaceae) is a bamboo species that is part of the traditional Chinese medicine pharmacopoeia. Compounds and extracts from this species have shown potential applications towards several diseases. One of many complications found in obesity and diabetes is the link between elevated circulatory free fatty acids (FFAs) and chronic inflammation. This study aims to present a possible application of P. edulis extract in relieving inflammation caused by FFAs. Monocyte chemoattractant protein 1 (MCP-1/CCL2) is a pro-inflammatory cytokine implicated in chronic inflammation. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activator protein 1 (AP-1) are transcription factors activated in response to inflammatory stimuli, and upregulate pro-inflammatory cytokines such as MCP-1. This study examines the effect of P. edulis extract on cellular production of MCP-1 and on the NF-κB and AP-1 pathways in response to treatment with palmitic acid (PA), a FFA. Methodology/Principal Findings MCP-1 protein was measured by cytometric bead assay. NF-κB and AP-1 nuclear localization was detected by colorimetric DNA-binding ELISA. Relative MCP-1 mRNA was measured by real-time quantitative PCR. Murine cells were treated with PA to induce inflammation. PA increased expression of MCP-1 mRNA and protein, and increased nuclear localization of NF-κB and AP-1. Adding bamboo extract (BEX) inhibited the effects of PA, reduced MCP-1 production, and inhibited nuclear translocation of NF-κB and AP-1 subunits. Compounds isolated from BEX inhibited MCP-1 secretion with different potencies. Conclusions/Significance PA induced MCP-1 production in murine adipose, muscle, and liver cells. BEX ameliorated PA-induced production of MCP-1 by inhibiting nuclear translocation of NF-κB and AP-1. Two O-methylated flavones were isolated from BEX with functional effects on MCP-1 production. These results may represent a possible therapeutic

  14. A plastic relationship between vinculin-mediated tension and adhesion complex area defines adhesion size and lifetime

    NASA Astrophysics Data System (ADS)

    Hernández-Varas, Pablo; Berge, Ulrich; Lock, John G.; Strömblad, Staffan

    2015-06-01

    Cell-matrix adhesions are central mediators of mechanotransduction, yet the interplay between force and adhesion regulation remains unclear. Here we use live cell imaging to map time-dependent cross-correlations between vinculin-mediated tension and adhesion complex area, revealing a plastic, context-dependent relationship. Interestingly, while an expected positive cross-correlation dominated in mid-sized adhesions, small and large adhesions display negative cross-correlation. Furthermore, although large changes in adhesion complex area follow vinculin-mediated tension alterations, small increases in area precede vinculin-mediated tension dynamics. Modelling based on this mapping of the vinculin-mediated tension-adhesion complex area relationship confirms its biological validity, and indicates that this relationship explains adhesion size and lifetime limits, keeping adhesions focal and transient. We also identify a subpopulation of steady-state adhesions whose size and vinculin-mediated tension become stabilized, and whose disassembly may be selectively microtubule-mediated. In conclusion, we define a plastic relationship between vinculin-mediated tension and adhesion complex area that controls fundamental cell-matrix adhesion properties.

  15. Physiological and pathological implications of semicarbazide-sensitive amine oxidase.

    PubMed

    Yu, Peter H; Wright, Shannon; Fan, Ellen H; Lun, Zhao-Rong; Gubisne-Harberle, Diana

    2003-04-11

    Semicarbazide-sensitive amine oxidase (SSAO) catalyzes the deamination of primary amines. Such deamination has been shown capable of regulating glucose transport in adipose cells. It has been independently discovered that the primary structure of vascular adhesion protein-1 (VAP-1) is identical to SSAO. VAP-1 regulates leukocyte migration and is related to inflammation. Increased serum SSAO activities have been found in patients with diabetic mellitus, vascular disorders and Alzheimer's disease. The SSAO-catalyzed deamination of endogenous substrates, that is, methylamine and aminoacetone, led to production of toxic formaldehyde and methylglyoxal, hydrogen peroxide and ammonia, respectively. These highly reactive aldehydes have been shown to initiate protein cross-linkage, exacerbate advanced glycation of proteins and cause endothelial injury. Hydrogen peroxide contributes to oxidative stress. 14C-methylamine is converted to 14C-formaldehyde, which then forms labeled long-lasting protein adduct in rodents. Chronic methylamine treatment increased the excretion of malondialdehyde and microalbuminuria, and enhanced the formation of fatty streaks in C57BL/6 mice fed with an atherogenic diet. Treatment with selective SSAO inhibitor reduces atherogenesis in KKAy diabetic mice fed with high-cholesterol diet. Aminoguanidine, which blocks advanced glycation and reduces nephropathy in animals, is in fact more potent at inhibiting SSAO than its effect on glycation. It suggests that SSAO is involved in vascular disorders under certain pathological conditions. Although SSAO has been known for several decades, its physiological and pathological implications are just beginning to be recognized.

  16. Universal adhesive (glue composition) for electrical porcelain products

    SciTech Connect

    Khristoforov, K.K.; Belen'kaya, E.S.; Omel'chenko, Y.A.; Vinogradova, T.K.

    1986-05-01

    The aim of this work is to develop an adhesive for porcelain insulators that exhibits high physicomechanical properties and increased resistance to the simultaneous action of heat and moisture. One method of solving this problem is to introduce special additives possessing hydrophobic (waterrepelling) properties into the adhesive composition during the process of its preparation. The adhesive based on the ED-20 epoxy resin and TEA hardened with 5 parts of AF-2 additive possesses higher resistance to the action of heat and moisture as compared to the adhesive used at the present time for assembling insulators. The improved and stable physiomechanical properties of the developed adhesive permit its use in any climactic conditions.

  17. Comparative biomorphologic analysis about three dentinal adhesives of last generations.

    PubMed

    Carini, F; Varia, P; Valenza, V

    2001-01-01

    The aim of this work consists in a comparative biomorphological analysis of the properties of infiltration and of adhesion to dental tissues of three among the more used enamel dentinal adhesives of the last generation known with the commercial name of Syntac, Excite and Prompt. The results have given evidence that Syntac has got short adhesion, Excite has got good capacity of infiltration and moderate adhesion, Prompt seems to possess a capacity of infiltration equal to Excite's one, but a better adhesion besides an easier modality of use.

  18. The effect of bending on the stresses in adhesive joints

    NASA Technical Reports Server (NTRS)

    Yuceoglu, U.; Updike, D. P.

    1975-01-01

    The problem of stress distribution in adhesive joints where two orthotropic plates are bonded through a flexible adhesive layer is analyzed. It is shown that the effect of bending of the adherends on the stresses in the adhesive layer is very significant. The transverse shear deformations of the adherends appear to have little influence on the adhesive layer stresses. The maximum transverse normal stress in the adhesive is shown to be larger than the maximum longitudinal shear stress. The method of solution is applied to several examples of specific joint geometries and material combinations, and is proven to be applicable to other related problems.

  19. Receptor FGFRL1 does not promote cell proliferation but induces cell adhesion

    PubMed Central

    YANG, XIAOCHEN; STEINBERG, FLORIAN; ZHUANG, LEI; BESSEY, RALPH; TRUEB, BEAT

    2016-01-01

    Fibroblast growth factor receptor (FGFR)-like protein 1 (FGFRL1) is the most recently discovered member of the FGFR family. Owing to the fact that it interacts with FGF ligands, but lacks the intracellular tyrosine kinase domain, several researchers have speculated that it may function as a decoy receptor and exert a negative effect on cell proliferation. In this study, we performed overexpression experiments with TetOn-inducible cell clones and downregulation experiments with siRNA oligonucleotides, and found that FGFRL1 had absolutely no effect on cell growth and proliferation. Likewise, we did not observe any influence of FGFRL1 on ERK1/2 activation and on the phosphorylation of 250 other signaling proteins analyzed by the Kinexus antibody microarray. On the other hand, with bacterial petri dishes, we observed a clear effect of FGFRL1 on cell adhesion during the initial hours after cell seeding. Our results suggest that FGFRL1 is a cell adhesion protein similar to the nectins rather than a signaling receptor similar to FGFR1-FGFR4. PMID:27220341

  20. Induction of Nerve Injury-Induced Protein 1 (Ninjurin 1) in Myeloid Cells in Rat Brain after Transient Focal Cerebral Ischemia

    PubMed Central

    Lee, Hye-Kyung; Lee, Hahnbie; Luo, Lidan

    2016-01-01

    Nerve injury-induced protein-1 (Ninjurin-1, Ninj1) was initially identified as a novel adhesion molecule in rat sciatic nerve and to be up-regulated in neurons and Schwann cells of distal nerve segments after nerve transection or crush injury. Recently, Ninj1 was found to act as a modulator of cell migration, angiogenesis, and apoptosis. Accumulating evidence indicates that innate immune response plays beneficial and deleterious roles in brain ischemia, and the trans-endothelial migration of blood-derived immune cells is key initiator of this response. In the present study, we examined the expression profile and cellular distribution of Ninj1 in rat brain after transient focal cerebral ischemia. Ninj1 expression was found to be significantly induced in cortical penumbras 1 day after 60 min of middle cerebral artery occlusion (MCAO) and to increase gradually for 8 days and then declined. In infarction cores of cortices, patterns of Ninj1 expression were similar to those observed in cortical penumbras, except induction was maintained for 10 days. At 1 day post-MCAO, Ninj1 inductions were detected mainly in neutrophils and endothelial cells in both infarction cores and penumbras, but reactive macrophages were the major cellular expressers of Ninj1 at 4 days post-MCAO. Expressional induction in reactive macrophages was maintained in infarction cores after 12 days post-MCAO but not in penumbras. These dynamic expressions of Ninj1 in different immune cells at different times suggest that this protein performs various, critical roles in the modulation of acute and delayed immune responses in the postischemic brain. PMID:27122992

  1. The multidrug resistance-associated protein 1 transports methoxychlor and protects the seminiferous epithelium from injury.

    PubMed

    Tribull, Tiffany E; Bruner, Richard H; Bain, Lisa J

    2003-04-30

    We examined the ability of the multidrug resistance-associated protein 1 (MRP1/ABCC1) to transport pesticides, as this transporter mediates the cellular efflux of a variety of xenobiotics, typically as glucuronide, sulfate, or glutathione conjugates. NIH3T3 cells stably expressing MRP1 were 3.37-fold more resistant to the toxicity of fenitrothion, 3.12-fold more resistant to chlorpropham, and 2.5-fold more resistant to methoxychlor, a pesticide with estrogenic and anti-androgenic metabolites. The cells expressing MRP1 also eliminated methoxychlor two times more rapidly than their mock-transfected counterparts. We then examined whether mrp1 expression could alter the toxicity of methoxychlor in vivo using male FVB/mrp1 knockout mice (FVB/mrp1-/-). Both control and knockout mice were fed 25 mg/kg methoxychlor in honey for 39 days, and its effects on testicular morphology were examined. Methoxychlor treatment did not significantly affect testicular morphology in the FVB mice, but markedly reduced the number of developing spermatocytes in the FVB/mrp1-/- mice. These results suggest that MRPI may play a role in protecting the seminiferous tubules from methoxychlor-induced damage.

  2. Structure of WDR5 bound to Mixed Lineage Leukemia protein-1 peptide

    SciTech Connect

    Patel, A.; Dharmarajan, V; Cosgrove, M

    2008-01-01

    The mixed lineage leukemia protein-1 (MLL1) catalyzes histone H3 lysine 4 methylation and is regulated by interaction with WDR5 (WD-repeat protein-5), RbBP5 (retinoblastoma-binding protein-5), and the Ash2L (absent, small, homeotic discs-2-like) oncoprotein. In the accompanying investigation, we describe the identification of a conserved arginine containing motif, called the 'Win' or WDR5 interaction motif, that is essential for the assembly and H3K4 dimethylation activity of the MLL1 core complex. Here we present a 1.7-A crystal structure of WDR5 bound to a peptide derived from the MLL1 Win motif. Our results show that Arg-3765 of MLL1 is bound in the same arginine binding pocket on WDR5 that was previously suggested to bind histone H3. Thermodynamic binding experiments show that the MLL1 Win peptide is preferentially recognized by WDR5. These results are consistent with a model in which WDR5 recognizes Arg-3765 of MLL1, which is essential for the assembly and enzymatic activity of the MLL1 core complex.

  3. Behavioral analysis of the huntingtin-associated protein 1 ortholog trak-1 in Caenorhabditis elegans.

    PubMed

    Norflus, Fran; Bu, Jingnan; Guyton, Evon; Gutekunst, Claire-Anne

    2016-09-01

    The precise role of huntingtin-associated protein 1 (HAP1) is not known, but studies have shown that it is important for early development and survival. A Caenorhabditis elegans ortholog of HAP1, T27A3.1 (also called trak-1), has been found and is expressed in a subset of neurons. Potential behavioral functions of three knockout lines of T27A3.1 were examined. From its suspected role in mice we hypothesize that T27A3.1 might be involved in egg hatching and early growth, mechanosensation, chemosensation, sensitivity to osmolarity, and synaptic transmission. Our studies show that the knockout worms are significantly different from the wild-type (WT) worms only in the synaptic transmission test, which was measured by adding aldicarb, an acetylcholinesterase inhibitor. The change in function was determined by measuring the number of worms paralyzed. However, when the T27A3.1 worms were tested for egg hatching and early growth, mechanosensation, chemosensation, and sensitivity to osmolarity, there were no significant differences between the knockout and WT worms. © 2016 Wiley Periodicals, Inc. PMID:27319755

  4. Heterochromatin Protein 1 Is Involved in Control of Telomere Elongation in Drosophila melanogaster

    PubMed Central

    Savitsky, Mikhail; Kravchuk, Oksana; Melnikova, Larisa; Georgiev, Pavel

    2002-01-01

    Telomeres of Drosophila melanogaster contain arrays of the retrotransposon-like elements HeT-A and TART. Their transposition to broken chromosome ends has been implicated in chromosome healing and telomere elongation. We have developed a genetic system which enables the determination of the frequency of telomere elongation events and their mechanism. The frequency differs among lines with different genotypes, suggesting that several genes are in control. Here we show that the Su(var)2-5 gene encoding heterochromatin protein 1 (HP1) is involved in regulation of telomere length. Different Su(var)2-5 mutations in the heterozygous state increase the frequency of HeT-A and TART attachment to the broken chromosome end by more than a hundred times. The attachment occurs through either HeT-A/TART transposition or recombination with other telomeres. Terminal DNA elongation by gene conversion is greatly enhanced by Su(var)2-5 mutations only if the template for DNA synthesis is on the same chromosome but not on the homologous chromosome. The Drosophila lines bearing the Su(var)2-5 mutations maintain extremely long telomeres consisting of HeT-A and TART for many generations. Thus, HP1 plays an important role in the control of telomere elongation in D. melanogaster. PMID:11940677

  5. BRCA-associated protein 1 mutant cholangiocarcinoma: an aggressive disease subtype

    PubMed Central

    Al-Shamsi, Humaid O.; Anand, Deepa; Shroff, Rachna T.; Jain, Apurva; Zuo, Mingxin; Conrad, Claudius; Vauthey, Jean-Nicolas

    2016-01-01

    Background BRCA-associated protein 1, an enzyme encoded by the BAP1 gene, is commonly mutated in uveal melanoma, mesothelioma, and renal cancers. Tumors with BAP1 mutation follow an aggressive course. BAP1 mutations have also been observed in cholangiocarcinoma (CCA). The clinical phenotype of BAP1 mutant CCA may yield useful prognostic and therapeutic information but has not been defined. Methods The records of CCA patients who underwent next-generation sequencing (NGS) were reviewed, and data on clinical, histopathological, genetic, and radiological features; response to therapy; time to progression; and survival were analyzed. Results Twenty-two cases of BAP1-mutation associated CCA were diagnosed from January 1, 2009, to February 1, 2015, at our center. Twenty patients had intrahepatic CCA and two had extrahepatic CCA. Tumor sizes (largest dimension) ranged from 2 to 16 cm (mean, 8.5 cm). Twelve patients had tumors that were poorly differentiated. Majority of the patients had advanced disease at presentation and 13 had bone metastases. Thirteen patients (59%) experienced rapidly progressive disease following primary therapy (chemotherapy or surgical resection). The mean time to tumor progression was 3.8 months after the first line chemotherapy. Conclusions BAP1 mutation in CCA may be associated with aggressive disease and poor response to standard therapies. Therefore, BAP1-targeted therapies need to be investigated. PMID:27563445

  6. Anthocyanidins inhibit activator protein 1 activity and cell transformation: structure-activity relationship and molecular mechanisms.

    PubMed

    Hou, De-Xing; Kai, Keiko; Li, Jian-Jian; Lin, Shigang; Terahara, Norihiko; Wakamatsu, Mika; Fujii, Makoto; Young, Mattew R; Colburn, Nancy

    2004-01-01

    Anthocyanins are the chemical components that give the intense color to many fruits and vegetables, such as blueberries, red cabbages and purple sweet potatoes. Extensive studies have indicated that anthocyanins have strong antioxidant activities. To investigate the mechanism of anthocyanidins as an anticancer food source, six kinds of anthocyanidins representing the aglycons of most anthocyanins, were used to examine their effects on tumor promotion in mouse JB6 cells, a validated model for screening cancer chemopreventive agents and elucidating the molecular mechanisms. Of the six anthocyanins tested, only those with an ortho-dihydroxyphenyl structure on the B-ring suppressed 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation and activator protein-1 transactivation, suggesting that the ortho-dihydroxyphenyl may contribute to the inhibitory action. Delphinidin, but not peonidin, blocked the phosphorylation of protein kinases in the extracellular signal-regulated protein kinase (ERK) pathway at early times and the c-Jun N-terminal kinase (JNK) signaling pathway at later times. p38 kinase was not inhibited by delphinidin. Furthermore, two mitogen-activated protein kinase (MAPK) specific inhibitors (SP600125 for JNK and UO126 for ERK) could specifically block the activation of JNK and ERK and cell transformation. Those results demonstrate that anthocyanidins contribute to the inhibition of tumorigenesis by blocking activation of the MAPK pathway. These findings provide the first molecular basis for the anticarcinogenic action of anthocyanidins. PMID:14514663

  7. NAP-1, Nucleosome assembly protein 1, a histone chaperone involved in Drosophila telomeres.

    PubMed

    López-Panadès, Elisenda; Casacuberta, Elena

    2016-03-01

    Telomere elongation is a function that all eukaryote cells must accomplish in order to guarantee, first, the stability of the end of the chromosomes and second, to protect the genetic information from the inevitable terminal erosion. The targeted transposition of the telomere transposons HeT-A, TART and TAHRE perform this function in Drosophila, while the telomerase mechanism elongates the telomeres in most eukaryotes. In order to integrate telomere maintenance together with cell cycle and metabolism, different components of the cell interact, regulate, and control the proteins involved in telomere elongation. Different partners of the telomerase mechanism have already been described, but in contrast, very few proteins have been related with assisting the telomere transposons of Drosophila. Here, we describe for the first time, the implication of NAP-1 (Nucleosome assembly protein 1), a histone chaperone that has been involved in nuclear transport, transcription regulation, and chromatin remodeling, in telomere biology. We find that Nap-1 and HeT-A Gag, one of the major components of the Drosophila telomeres, are part of the same protein complex. We also demonstrate that their close interaction is necessary to guarantee telomere stability in dividing cells. We further show that NAP-1 regulates the transcription of the HeT-A retrotransposon, pointing to a positive regulatory role of NAP-1 in telomere expression. All these results facilitate the understanding of the transposon telomere maintenance mechanism, as well as the integration of telomere biology with the rest of the cell metabolism.

  8. A mitochondrial uncoupling artifact can be caused by expression of uncoupling protein 1 in yeast.

    PubMed Central

    Stuart, J A; Harper, J A; Brindle, K M; Jekabsons, M B; Brand, M D

    2001-01-01

    Uncoupling protein 1 (UCP1) from mouse was expressed in yeast and the specific (GDP-inhibitable) and artifactual (GDP-insensitive) effects on mitochondrial uncoupling were assessed. UCP1 provides a GDP-inhibitable model system to help interpret the uncoupling effects of high expression in yeast of other members of the mitochondrial carrier protein family, such as the UCP1 homologues UCP2 and UCP3. Yeast expressing UCP1 at modest levels (approx. 1 microg/mg of mitochondrial protein) showed no growth defect, normal rates of chemically uncoupled respiration and an increased non-phosphorylating proton conductance that was completely GDP-sensitive. The catalytic-centre activity of UCP1 in these yeast mitochondria was similar to that in mammalian brown-adipose-tissue mitochondria. However, yeast expressing UCP1 at higher levels (approx. 11 microg/mg of mitochondrial protein) showed a growth defect. Their mitochondria had depressed chemically uncoupled respiration rates and an increased proton conductance that was partly GDP-insensitive. Thus, although UCP1 shows native behaviour at modest levels of expression in yeast, higher levels (or rates) of expression can lead to an uncoupling that is not a physiological property of the native protein and is therefore artifactual. This observation might be important in the interpretation of results from experiments in which the functions of UCP1 homologues are verified by their ability to uncouple yeast mitochondria. PMID:11389685

  9. Detection of Aichi virus with antibody targeting of conserved viral protein 1 epitope.

    PubMed

    Chen, Yao-Shen; Chen, Bao-Chen; Lin, You-Sheng; Chang, Jenn-Tzong; Huang, Tsi-Shu; Chen, Jih-Jung; Chang, Tsung-Hsien

    2013-10-01

    Aichi virus (AiV) is an emerging single-stranded, positive-sense, non-enveloped RNA virus in the Picornaviridae that causes acute gastroenteritis in humans. The first case of AiV infection in Taiwan was diagnosed in a human neonate with enterovirus-associated symptoms; the virus was successfully isolated and propagated. To establish a method to detect AiV, we analyzed the antigen epitope and generated a polyclonal antibody against AiV viral protein 1 (VP1). This peptide-purified anti-AiV VP1 antibody showed high specificity against AiV VP1 without cross-reaction to nine other tested strains of Picornaviruses. The anti-AiV VP1 antibody was used in immunofluorescence analysis, immunoblotting, and enzyme-linked immunosorbent assay to elucidate the cell tropism and replication kinetics of AiV. Use of the anti-AiV VP1 antibody also revealed AiV infection restriction with interferon type I and polyI/C antiviral treatment. The AiV infection and detection system may provide an in vitro platform for AiV virology study.

  10. Spliced X-box Binding Protein 1 Couples the Unfolded Protein Response to Hexosamine Biosynthetic Pathway

    PubMed Central

    Wang, Zhao V.; Deng, Yingfeng; Gao, Ningguo; Pedrozo, Zully; Li, Dan L.; Morales, Cyndi R.; Criollo, Alfredo; Luo, Xiang; Tan, Wei; Jiang, Nan; Lehrman, Mark A.; Rothermel, Beverly A.; Lee, Ann-Hwee; Lavandero, Sergio; Mammen, Pradeep P.A.; Ferdous, Anwarul; Gillette, Thomas G.; Scherer, Philipp E.; Hill, Joseph A.

    2014-01-01

    SUMMARY The hexosamine biosynthetic pathway (HBP) generates UDP-GlcNAc (uridine diphosphate N-acetylglucosamine) for glycan synthesis and O-linked GlcNAc (O-GlcNAc) protein modifications. Despite the established role of the HBP in metabolism and multiple diseases, regulation of the HBP remains largely undefined. Here, we show that spliced X-box binding protein 1 (Xbp1s), the most conserved signal transducer of the unfolded protein response (UPR), is a direct transcriptional activator of the HBP. We demonstrate that the UPR triggers HBP activation via Xbp1s-dependent transcription of genes coding for key, rate-limiting enzymes. We further establish that this previously unrecognized UPR-HBP axis is triggered in a variety of stress conditions. Finally, we demonstrate a physiologic role for the UPR-HBP axis, by showing that acute stimulation of Xbp1s in heart by ischemia/reperfusion confers robust cardioprotection in part through induction of the HBP. Collectively, these studies reveal that Xbp1s couples the UPR to the HBP to protect cells under stress. PMID:24630721

  11. Spliced X-box binding protein 1 couples the unfolded protein response to hexosamine biosynthetic pathway.

    PubMed

    Wang, Zhao V; Deng, Yingfeng; Gao, Ningguo; Pedrozo, Zully; Li, Dan L; Morales, Cyndi R; Criollo, Alfredo; Luo, Xiang; Tan, Wei; Jiang, Nan; Lehrman, Mark A; Rothermel, Beverly A; Lee, Ann-Hwee; Lavandero, Sergio; Mammen, Pradeep P A; Ferdous, Anwarul; Gillette, Thomas G; Scherer, Philipp E; Hill, Joseph A

    2014-03-13

    The hexosamine biosynthetic pathway (HBP) generates uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) for glycan synthesis and O-linked GlcNAc (O-GlcNAc) protein modifications. Despite the established role of the HBP in metabolism and multiple diseases, regulation of the HBP remains largely undefined. Here, we show that spliced X-box binding protein 1 (Xbp1s), the most conserved signal transducer of the unfolded protein response (UPR), is a direct transcriptional activator of the HBP. We demonstrate that the UPR triggers HBP activation via Xbp1s-dependent transcription of genes coding for key, rate-limiting enzymes. We further establish that this previously unrecognized UPR-HBP axis is triggered in a variety of stress conditions. Finally, we demonstrate a physiologic role for the UPR-HBP axis by showing that acute stimulation of Xbp1s in heart by ischemia/reperfusion confers robust cardioprotection in part through induction of the HBP. Collectively, these studies reveal that Xbp1s couples the UPR to the HBP to protect cells under stress.

  12. Functional and Immunological Relevance of Anaplasma marginale Major Surface Protein 1a Sequence and Structural Analysis

    PubMed Central

    Cabezas-Cruz, Alejandro; Passos, Lygia M. F.; Lis, Katarzyna; Kenneil, Rachel; Valdés, James J.; Ferrolho, Joana; Tonk, Miray; Pohl, Anna E.; Grubhoffer, Libor; Zweygarth, Erich; Shkap, Varda; Ribeiro, Mucio F. B.; Estrada-Peña, Agustín; Kocan, Katherine M.; de la Fuente, José

    2013-01-01

    Bovine anaplasmosis is caused by cattle infection with the tick-borne bacterium, Anaplasma marginale. The major surface protein 1a (MSP1a) has been used as a genetic marker for identifying A. marginale strains based on N-terminal tandem repeats and a 5′-UTR microsatellite located in the msp1a gene. The MSP1a tandem repeats contain immune relevant elements and functional domains that bind to bovine erythrocytes and tick cells, thus providing information about the evolution of host-pathogen and vector-pathogen interactions. Here we propose one nomenclature for A. marginale strain classification based on MSP1a. All tandem repeats among A. marginale strains were classified and the amino acid variability/frequency in each position was determined. The sequence variation at immunodominant B cell epitopes was determined and the secondary (2D) structure of the tandem repeats was modeled. A total of 224 different strains of A. marginale were classified, showing 11 genotypes based on the 5′-UTR microsatellite and 193 different tandem repeats with high amino acid variability per position. Our results showed phylogenetic correlation between MSP1a sequence, secondary structure, B-cell epitope composition and tick transmissibility of A. marginale strains. The analysis of MSP1a sequences provides relevant information about the biology of A. marginale to design vaccines with a cross-protective capacity based on MSP1a B-cell epitopes. PMID:23776456

  13. Heterochromatin Protein 1 Binding Protein 3 Expression as a Candidate Marker of Intrinsic 5-Fluorouracil Resistance

    PubMed Central

    HADAC, JAMIE N.; MILLER, DEVON D.; GRIMES, IAN C.; CLIPSON, LINDA; NEWTON, MICHAEL A.; SCHELMAN, WILLIAM R.; HALBERG, RICHARD B.

    2016-01-01

    Background Despite receiving post-operative 5-fluorouracil (5-FU)-based chemotherapy, approximately 50% of patients with stage IIIC colon cancer experience recurrence. Currently, no molecular signature can predict response to 5-FU. Materials and Methods Mouse models of colon cancer have been developed and characterized. Individual tumors in these mice can be longitudinally monitored and assessed to identify differences between those that are responsive and those that are resistant to therapy. Gene expression was analyzed in serial biopsies that were collected before and after treatment with 5-FU. Colon tumors had heterogeneous responses to treatment with 5-FU. Microarray analysis of pretreatment biopsies revealed that Hp1bp3, a gene encoding heterochromatin protein 1 binding protein 3, was differentially expressed between sensitive and resistant tumors. Conclusion Using mouse models of human colorectal cancer, Hp1bp3 was identified as a candidate marker of intrinsic 5-FU resistance and may represent a potential biomarker for patient stratification or a target of clinical importance. PMID:26976970

  14. Distribution of the SynDIG4/proline-rich transmembrane protein 1 in rat brain.

    PubMed

    Kirk, Lyndsey M; Ti, Shu W; Bishop, Hannah I; Orozco-Llamas, Mayra; Pham, Michelle; Trimmer, James S; Díaz, Elva

    2016-08-01

    The modulation of AMPA receptor (AMPAR) content at synapses is thought to be an underlying molecular mechanism of memory and learning. AMPAR content at synapses is highly plastic and is regulated by numerous AMPAR accessory transmembrane proteins such as TARPs, cornichons, and CKAMPs. SynDIG (synapse differentiation-induced gene) defines a family of four genes (SynDIG1-4) expressed in distinct and overlapping patterns in the brain. SynDIG1 was previously identified as a novel transmembrane AMPAR-associated protein that regulates synaptic strength. The related protein SynDIG4 [also known as Prrt1 (proline-rich transmembrane protein 1)] has recently been identified as a component of AMPAR complexes. In this study, we show that SynDIG1 and SynDIG4 have distinct yet overlapping patterns of expression in the central nervous system, with SynDIG4 having especially prominent expression in the hippocampus and particularly within CA1. In contrast to SynDIG1 and other traditional AMPAR auxiliary subunits, SynDIG4 is de-enriched at the postsynaptic density and colocalizes with extrasynaptic GluA1 puncta in primary dissociated neuron culture. These results indicate that, although SynDIG4 shares sequence similarity with SynDIG1, it might act through a unique mechanism as an auxiliary factor for extrasynaptic GluA1-containing AMPARs. J. Comp. Neurol. 524:2266-2280, 2016. © 2015 Wiley Periodicals, Inc.

  15. Regulation of muscle contraction by Drebrin-like protein 1 probed by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Garces, Renata; Butkevich, Eugenia; Platen, Mitja; Schmidt, Christoph F.; Biophysics Team

    Sarcomeres are the fundamental contractile units of striated muscle cells. They are composed of a variety of structural and regulatory proteins functioning in a precisely orchestrated fashion to enable coordinated force generation in striated muscles. Recently, we have identified a C. elegans drebrin-like protein 1 (DBN-1) as a novel sarcomere component, which stabilizes actin filaments during muscle contraction. To further characterize the function of DBN-1 in muscle cells, we generated a new dbn-1 loss-of-function allele. Absence of DBN-1 resulted in a unique worm movement phenotype, characterized by hyper-bending. It is not clear yet if DBN-1 acts to enhance or reduce the capacity for contraction. We present here an experimental mechanical study on C. elegans muscle mechanics. We measured the stiffness of the worm by indenting living C. eleganswith a micron-sized sphere adhered to the cantilever of an atomic force microscope (AFM). Modeling the worm as a pressurized elastic shell allows us to monitor the axial tension in the muscle through the measured stiffness. We compared responses of wild-type and mutant C. elegans in which DBN-1 is not expressed..

  16. Interaction between Cartilage Oligomeric Matrix Protein and Extracellular Matrix Protein 1 Mediates Endochondral Bone Growth

    PubMed Central

    Kong, Li; Tian, Qingyun; Guo, Fengjin; Mucignat, Maria T.; Perris, Roberto; Sercu, Sandy; Merregaert, Joseph; Di Cesare, Paul E.; Liu, Chuan-ju

    2010-01-01

    In an effort to define the biological functions of COMP, a functional genetic screen was performed. This led to the identification of extracellular matrix protein 1 (ECM1) as a novel COMP-associated partner. COMP directly binds to ECM1 both in vitro and in vivo. The EGF domain of COMP and the C-terminus of ECM1 mediate the interaction between them. COMP and ECM1 Colocalize in the Growth Plates in Vivo. ECM1 inhibits chondrocyte hypertrophy, matrix mineralization, and endochondral bone formation, and COMP overcomes the inhibition by ECM1. In addition, COMP-mediated neutralization of ECM1 inhibition depends on their interaction, since COMP largely fails to overcome the ECM1 inhibition in the presence of the EGF domain of COMP, which disturbs the association of COMP and ECM1. These findings provide the first evidence linking the association of COMP and ECM1 and the biological significance underlying the interaction between them in regulating endochondral bone growth. PMID:20138147

  17. Insights on regulation and function of the iron regulatory protein 1 (IRP1).

    PubMed

    Wang, Jian; Chen, Guohua; Filebeen, Carine; Pantopoulos, Kostas

    2008-01-01

    Iron regulatory protein 1 (IRP1) controls the translation or stability of several mRNAs by binding to iron responsive elements (IREs) within their untranslated regions. Its activity is regulated by an unusual iron-sulfur cluster (ICS) switch. Thus, in iron-replete cells, IRP1 assembles a cubane [4Fe-4S] cluster that prevents RNA-binding activity and renders the protein to cytosolic aconitase. We show that wild type or mutant forms of IRP1 that fail to assemble a [4Fe-4S] cluster are sensitized for iron-dependent degradation by the ubiquitin-proteasome pathway. The regulation of IRP1 abundance poses an alternative mechanism to prevent accumulation of inappropriately high IRE-binding activity when the ICS assembly pathway is impaired. To study functional aspects of IRP1, we overexpressed wild type or mutant forms of the protein in human H1299 lung cancer cells in a tetracycline-inducible fashion, and analyzed how this affects cell growth. While the induction of IRP1 did not affect cell proliferation in culture, it dramatically reduced the capacity of the cells to form solid tumor xenografts in nude mice. These data provide a first link between IRP1 and cancer.

  18. Gamma Interferon-Induced Guanylate Binding Protein 1 Is a Novel Actin Cytoskeleton Remodeling Factor

    PubMed Central

    Ostler, Nicole; Britzen-Laurent, Nathalie; Liebl, Andrea; Naschberger, Elisabeth; Lochnit, Günter; Ostler, Markus; Forster, Florian; Kunzelmann, Peter; Ince, Semra; Supper, Verena; Praefcke, Gerrit J. K.; Schubert, Dirk W.; Stockinger, Hannes; Herrmann, Christian

    2014-01-01

    Gamma interferon (IFN-γ) regulates immune defenses against viruses, intracellular pathogens, and tumors by modulating cell proliferation, migration, invasion, and vesicle trafficking processes. The large GTPase guanylate binding protein 1 (GBP-1) is among the cellular proteins that is the most abundantly induced by IFN-γ and mediates its cell biologic effects. As yet, the molecular mechanisms of action of GBP-1 remain unknown. Applying an interaction proteomics approach, we identified actin as a strong and specific binding partner of GBP-1. Furthermore, GBP-1 colocalized with actin at the subcellular level and was both necessary and sufficient for the extensive remodeling of the fibrous actin structure observed in IFN-γ-exposed cells. These effects were dependent on the oligomerization and the GTPase activity of GBP-1. Purified GBP-1 and actin bound to each other, and this interaction was sufficient to impair the formation of actin filaments in vitro, as demonstrated by atomic force microscopy, dynamic light scattering, and fluorescence-monitored polymerization. Cosedimentation and band shift analyses demonstrated that GBP-1 binds robustly to globular actin and slightly to filamentous actin. This indicated that GBP-1 may induce actin remodeling via globular actin sequestering and/or filament capping. These results establish GBP-1 as a novel member within the family of actin-remodeling proteins specifically mediating IFN-γ-dependent defense strategies. PMID:24190970

  19. Auxin binding protein 1 (ABP1) is not required for either auxin signaling or Arabidopsis development.

    PubMed

    Gao, Yangbin; Zhang, Yi; Zhang, Da; Dai, Xinhua; Estelle, Mark; Zhao, Yunde

    2015-02-17

    Auxin binding protein 1 (ABP1) has been studied for decades. It has been suggested that ABP1 functions as an auxin receptor and has an essential role in many developmental processes. Here we present our unexpected findings that ABP1 is neither required for auxin signaling nor necessary for plant development under normal growth conditions. We used our ribozyme-based CRISPR technology to generate an Arabidopsis abp1 mutant that contains a 5-bp deletion in the first exon of ABP1, which resulted in a frameshift and introduction of early stop codons. We also identified a T-DNA insertion abp1 allele that harbors a T-DNA insertion located 27 bp downstream of the ATG start codon in the first exon. We show that the two new abp1 mutants are null alleles. Surprisingly, our new abp1 mutant plants do not display any obvious developmental defects. In fact, the mutant plants are indistinguishable from wild-type plants at every developmental stage analyzed. Furthermore, the abp1 plants are not resistant to exogenous auxin. At the molecular level, we find that the induction of known auxin-regulated genes is similar in both wild-type and abp1 plants in response to auxin treatments. We conclude that ABP1 is not a key component in auxin signaling or Arabidopsis development. PMID:25646447

  20. The investigation on the role of mitochondrial fusion protein 1 in the development of myopia

    PubMed Central

    Cai, Yun-Lin; Zou, Yun-Chun; Lei, Jia-Hong; Zeng, Guan-Peng; Wang, Ying

    2016-01-01

    Purpose: The aim of this study is to preliminarily investigate the expression of mitochondrial fusion protein 1 (MFN1) in a lens-induced animal myopia (LIM) model and to explore the relationship between MFN1 and the visual development. Materials and Methods: MFN1 gene expression in guinea pigs was examined during the development of minus LIM, 15 tri-colored guinea pigs were obtained, and one eye of each pig was randomly selected and treated with −7.00D lenses. Ocular refraction and axial length were collected before intervention and 1, 2, and 3 weeks after intervention. After the refraction and axial length measurements at 1, 2, and 3 weeks of lens intervention, five guinea pigs were randomly selected. MFN1 expression in the retina of both eyes was tested by immunohistochemistry technique. Results: MFN1-positive cells could be observed in the retina of both eyes. The positive cells in the LIM eyes were staining deeper, and much more positive cells could be observed. Furthermore, MFN1-positive expression could be seen mainly in ganglion cells after 1 week of minus lens intervention, and with time extension, more and more positive cells appeared in the rod-cone cell and bipolar cell layer, and this phenomenon could not be found in the normal control eyes. Conclusion: This study suggested that MFN1 might be correlated to the development of myopia. PMID:27609161