scholarly journals A peptide mimetic of the mycobacterial mannosylated lipoarabinomannan: characterization and potential applications

2007 ◽  
Vol 56 (5) ◽  
pp. 579-586 ◽  
Author(s):  
Ayelet Barenholz ◽  
Avi-Hai Hovav ◽  
Yolanta Fishman ◽  
Galia Rahav ◽  
Jonathan M. Gershoni ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Phage Display ◽  
Peptide Libraries ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Keyhole Limpet Haemocyanin ◽  
Peptide Epitope ◽  
Specificity And Sensitivity ◽  
Potential Applications ◽  
Good Substitute

Mannosylated lipoarabinomannan (ManLAM), a complex lipoglycan, is a major component of Mycobacterium tuberculosis, the agent of tuberculosis (TB), and is an antigen used for serological diagnosis of TB. Screening random phage-display peptide libraries with anti-ManLAM mAb CS40 for peptide epitope mimics (mimotopes) led to the isolation of a panel of peptides. One of these peptides (B11) was characterized as a ManLAM mimotope: it bound the anti-ManLAM CS40 mAb and competed with ManLAM for antibody binding. Mice immunized with keyhole limpet haemocyanin-conjugated B11 peptide in a proper adjuvant developed antibodies that recognized ManLAM. Competition experiments demonstrated that the B11 peptide inhibited binding of mAb CS40 to ManLAM in a concentration-dependent manner. The data indicated that the affinity of CS40 mAb to B11 (K D 1.33×10−8) is higher than its affinity to ManLAM (K D 3.00×10−7). The sera of TB patients, as well as the sera of mice experimentally infected with M. tuberculosis, contained significant levels of antibodies that recognized both the B11 peptide and ManLAM. The specificity and sensitivity of the ELISA B11-based test were similar to those of the ELISA ManLAM-based test, indicating that the B11 antigen could be a good substitute for ManLAM serology for the diagnosis of TB.

Functional Analysis of Phage Display Selected Single-Chain Variable Antibody Fragments (scFvs) Specific for Anti-FVIII Antibodies

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1499-1499
Author(s):  
Kerstin Brettschneider ◽  
Anja Naumann ◽  
Sonja Neimanis ◽  
Joerg Kahle ◽  
Christine Heller ◽  
...  
Keyword(s):  
Phage Display ◽  
Hemophilia A ◽  
Antibody Fragments ◽  
Dependent Manner ◽  
Single Chain ◽  
Concentration Dependent Manner ◽  
Fviii Activity ◽  
Inhibitory Antibodies

Abstract The development of inhibitory antibodies against coagulation factor VIII (FVIII) is currently the most serious complication for hemophilia A patients that undergo FVIII replacement therapy. In addition, non-hemophilia A patients can spontaneously develop inhibitory auto-antibodies to FVIII, which results in acquired haemophilia A. The control of the allo- or autoimmune response to FVIII apparently includes the elicitation of anti-idiotypic antibodies. In this study the capacity of anti-idiotypic single-chain variable antibody fragments (scFvs) for neutralization of inhibitory anti-FVIII antibodies (FVIII inhibitors) was evaluated in vitro and in vivo. Anti-idiotypic scFvs were selected from phage-displayed libraries against murine monoclonal FVIII-specific inhibitors. As the majority of inhibitory antibodies is directed against the A2 or C2 domain of FVIII, strongly inhibitory A2- and C2-specific antibodies served as targets. Selected scFvs were expressed as scFv-Fc fusion proteins. Analysis of the scFv-Fcs by ELISA confirmed the specific binding to the cognate targets and binding studies via surface plasmon resonance revealed high affinities within the nanomolar range. Further characterization showed that binding of inhibitors to immobilized FVIII was blocked by specific scFv-Fcs in vitro. The ability of scFv-Fcs to neutralize their corresponding inhibitors was analyzed in a functional clotting assay. By adding scFv-Fcs to plasma spiked with inhibitors, FVIII activity was restored to 80% in a concentration dependent manner. FVIII knockout mice served as model organism for testing the capacity of scFv-Fcs to restore coagulation in vivo. Subsequent injection of FVIII following the injection of the inhibitors resulted in a largely reduced FVIII activity. However, FVIII activity was recovered in a concentration dependent manner by adding cognate anti-idiotypes. The scFv-Fcs were either preincubated with the corresponding inhibitor or added to the FVIII mixture without preincubation. The latter represents an adaption to a therapeutic setting. In conclusion, phage display selected anti-idiotypic scFvs are able to bind and effectively neutralize their target inhibitors in vitro and in vivo. Based on these promising results the potential of anti-idiotypic scFvs for the development of specific cell based immunotherapies for hemophilia A patients with inhibitors is currently under investigation. Disclosures No relevant conflicts of interest to declare.

Phage Display Screening of Epithelial Cell Monolayers Treated with EGTA: Identification of Peptide FDFWITP that Modulates Tight Junction Activity

2007 ◽  
Vol 12 (8) ◽  
pp. 1092-1101 ◽  
Author(s):  
Richard E. Herman ◽  
Ekaterina G. Makienko ◽  
Mary G. Prieve ◽  
Mark Fuller ◽  
Michael E. Houston ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Tight Junction ◽  
Phage Display ◽  
Tight Junctions ◽  
Phage Library ◽  
Junctional Complex ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cell Monolayers ◽  
Lysine Residues

Phage display was used to screen for peptides that modulate the activity of epithelial cell tight junctions. Panning with a phage library that displays random 7-mers was performed using monolayers of human bronchial epithelial cells (16HBE14o—) treated with a calcium chelator, ethylene glycol-bis(2-aminoethylether)- N, N, N′, N′-tetraacetic acid (EGTA), to increase accessibility to the junctional complex/paracellular space, followed by subtractive panning. A novel peptide, FDFWITP, identified as a potential tight junction modulator, was synthesized in linear and cyclic forms with lysine residues added to improve solubility. The cyclic form of the peptide reduced transepithelial electrical resistance (TER) in a concentration-dependent manner (80% reduction at 100 µM and 95% reduction at 500 µM) and was reversible within 2 h; the linear form only affected TER at the highest concentration. Interestingly, the constrained peptide did not increase permeation of the model small molecule, fluorescein. The highly selective activity of FDFWITP supports the hypothesis that ions and small molecules may be transported paracellularly across tight junctions by separate pathways. ( Journal of Biomolecular Screening 2007:1092-1101)

scholarly journals Steroid inhibition of calcitriol-induced prolactin production in GH4C1 cells. Specificity and sensitivity

1987 ◽  
Vol 241 (2) ◽  
pp. 397-401 ◽  
Author(s):  
J D Wark ◽  
V Gurtler
Keyword(s):  
Pituitary Tumour ◽  
Dependent Manner ◽  
Hormone Production ◽  
Concentration Dependent Manner ◽  
Dihydroxyvitamin D3 ◽  
Specificity And Sensitivity ◽  
Rat Pituitary ◽  
Increased Sensitivity ◽  
Ic50 Concentration ◽  
Glucocorticoid Effect

The induction of prolactin (PRL)-gene expression by calcitriol (1,25-dihydroxyvitamin D3, 1,25-dihydroxycholecalciferol) in clonal rat pituitary tumour (GH4C1) cells was selectively inhibited by cortisol [IC50 (concentration causing 50% inhibition) = 3.2-4.1 nM]. The steroid specificity of this effect was investigated and various steroids were found to inhibit calcitriol-stimulated PRL production with the following relative potencies: cortisol, 1; dexamethasone, 8; 11-deoxycortisol, 0.5; corticosterone, 0.4; aldosterone, 0.07; testosterone and oestradiol, less than 0.003. The steroid antagonist RU 38486 did not affect basal or calcitriol-stimulated PRL production, but antagonized the effect of 10 nM-cortisol in a concentration-dependent manner. Neither progesterone nor 11-deoxycortisol antagonized the effect of 10 nM-cortisol. Calcitriol-induced PRL production was 14 times more sensitive to dexamethasone inhibition than was non-stimulated PRL production. Growth-hormone production was stimulated by dexamethasone, in the presence or absence of calcitriol, with a concentration-dependence similar to that of dexamethasone inhibition of basal PRL production. These data indicate that steroid inhibition of calcitriol-stimulated PRL production is a specific glucocorticoid effect. The sensitivity of calcitriol-stimulated PRL production to dexamethasone was 14-26-fold greater than that of other measured responses in the same cells. Two of the possible explanations for this selectively increased sensitivity to glucocorticoids are: amplification of the glucocorticoid effect via an induced mediator; and the presence of very-high-affinity glucocorticoid-receptor-binding sites on DNA.

scholarly journals Highly Sensitive and Cost-Effective Portable Sensor for Early Gastric Carcinoma Diagnosis

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2639
Author(s):  
Saw Lin Oo ◽  
Shishir Venkatesh ◽  
Vaithinathan Karthikeyan ◽  
Clement Manohar Arava ◽  
Spoorthy Pathikonda ◽  
...  
Keyword(s):  
Gastric Carcinoma ◽  
High Specificity ◽  
Cost Effective ◽  
Electrical Current ◽  
Early Gastric Carcinoma ◽  
Rna Modification ◽  
Dependent Manner ◽  
Cancer Antigen ◽  
Concentration Dependent Manner ◽  
Specificity And Sensitivity

Facile and efficient early detection of cancer is a major challenge in healthcare. Herein we developed a novel sensor made from a polycarbonate (PC) membrane with nanopores, followed by sequence-specific Oligo RNA modification for early gastric carcinoma diagnosis. In this design, the gastric cancer antigen CA72-4 is specifically conjugated to the Oligo RNA, thereby inhibiting the electrical current through the PC membrane in a concentration-dependent manner. The device can determine the concentration of cancer antigen CA72-4 in the range from 4 to 14 U/mL, possessing a sensitivity of 7.029 µAU−1mLcm−2 with a linear regression (R2) of 0.965 and a lower detection limit of 4 U/mL. This device has integrated advantages including high specificity and sensitivity and being simple, portable, and cost effective, which collectively enables a giant leap for cancer screening technologies towards clinical use. This is the first report to use RNA aptamers to detect CA72-4 for gastric carcinoma diagnosis.

Enzymatic Extraction of Polysaccharides from Laminaria Japonica and their Free Radical Scavenging Activity and Antimicrobial Activity Evaluation

2012 ◽  
Vol 479-481 ◽  
pp. 605-610 ◽  
Author(s):  
Jing Chen ◽  
Miao Ping Tian ◽  
Shang Gui Deng ◽  
Xu Bo Fang
Keyword(s):  
Hydroxyl Radicals ◽  
Ph Value ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Laminaria Japonica ◽  
Dependent Manner ◽  
Scavenging Activity ◽  
Enzymatic Extraction ◽  
Concentration Dependent Manner ◽  
Potential Applications

Complex enzymes, including cellulase, pectinase and neutral protease were used for extraction of laminaria polysaccharides, which have a broad range of applications in the food, pharmaceutical, agricultural and chemical industries. The enzymatic extraction conditions were optimized and the maximum polysaccharides yield was achieved with the addition of 2.5% of enzymes under a pH value of 5.0 and temperature of 55 °C for 210 min. Polysaccharides prepared under the above conditions were effective against some pathogenic and spoilage microorganisms, including Salmonella sp, Bacillus subtilis, Enterococcus faecalis, Proteus vulgaris, Staphylococcus aureus, Escherichia coli, Pseudomonas fluorescens, with a diameter range of 5.1 ± 0.29-12.5 ± 0.78 mm. In addition, antioxidant activity of laminaria polysaccharides against hydroxyl radicals was also investigated and it was observed that the polysaccharides displayed obvious scavenging activity on hydroxyl radicals in concentration-dependent manner. Overall, polysaccharides from Laminaria Japonica demonstrated potential applications in food safety and control.

The Anti-Atherogenic Properties of Sesamin are Mediated via Improved Macrophage Cholesterol Efflux Through PPARγ1-LXRα and MAPK Signaling

2014 ◽  
Vol 84 (1-2) ◽  
pp. 79-91 ◽  
Author(s):  
Amin F. Majdalawieh ◽  
Hyo-Sung Ro
Keyword(s):  
Cholesterol Efflux ◽  
Transcriptional Activity ◽  
Molecular Mechanisms ◽  
Foam Cell ◽  
Mapk Signaling ◽  
Luciferase Reporter ◽  
Foam Cell Formation ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Macrophage Cholesterol Efflux

Background: Foam cell formation resulting from disrupted macrophage cholesterol efflux, which is triggered by PPARγ1 and LXRα, is a hallmark of atherosclerosis. Sesamin and sesame oil exert anti-atherogenic effects in vivo. However, the exact molecular mechanisms underlying such effects are not fully understood. Aim: This study examines the potential effects of sesamin (0, 25, 50, 75, 100 μM) on PPARγ1 and LXRα expression and transcriptional activity as well as macrophage cholesterol efflux. Methods: PPARγ1 and LXRα expression and transcriptional activity are assessed by luciferase reporter assays. Macrophage cholesterol efflux is evaluated by ApoAI-specific cholesterol efflux assays. Results: The 50 μM, 75 μM, and 100 μM concentrations of sesamin up-regulated the expression of PPARγ1 (p< 0.001, p < 0.001, p < 0.001, respectively) and LXRα (p = 0.002, p < 0.001, p < 0.001, respectively) in a concentration-dependent manner. Moreover, 75 μM and 100 μM concentrations of sesamin led to 5.2-fold (p < 0.001) and 6.0-fold (p<0.001) increases in PPAR transcriptional activity and 3.9-fold (p< 0.001) and 4.2-fold (p < 0.001) increases in LXR transcriptional activity, respectively, in a concentration- and time-dependent manner via MAPK signaling. Consistently, 50 μM, 75 μM, and 100 μM concentrations of sesamin improved macrophage cholesterol efflux by 2.7-fold (p < 0.001), 4.2-fold (p < 0.001), and 4.2-fold (p < 0.001), respectively, via MAPK signaling. Conclusion: Our findings shed light on the molecular mechanism(s) underlying sesamin’s anti-atherogenic effects, which seem to be due, at least in part, to its ability to up-regulate PPARγ1 and LXRα expression and transcriptional activity, improving macrophage cholesterol efflux. We anticipate that sesamin may be used as a therapeutic agent for treating atherosclerosis.

Neutrophil Elastase Potentiates Cathepsin G-lnduced Platelet Activation

1992 ◽  
Vol 68 (05) ◽  
pp. 570-576 ◽  
Author(s):  
Mary A Selak
Keyword(s):  
Neutrophil Elastase ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Creatine Phosphate ◽  
Dense Granule ◽  
Cathepsin G ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations

SummaryWe have previously demonstrated that human neutrophil cathepsin G is a strong platelet agonist that binds to a specific receptor. This work describes the effect of neutrophil elastase on cathepsin G-induced platelet responses. While platelets were not activated by high concentrations of neutrophil elastase by itself, elastase enhanced aggregation, secretion and calcium mobilization induced by low concentrations of cathepsin G. Platelet aggregation and secretion were potentiated in a concentration-dependent manner by neutrophil elastase with maximal responses observable at 200 nM. Enhancement was observed when elastase was preincubated with platelets for time intervals of 10–60 s prior to addition of a low concentration of cathepsin G and required catalytically-active elastase since phenylmethanesulphonyl fluoride-inhibited enzyme failed to potentiate cell activation. Neutrophil elastase potentiation of platelet responses induced by low concentrations of cathepsin G was markedly inhibited by creatine phosphate/creatine phosphokinase and/or indomethacin, indicating that the synergism between elastase and cathepsin G required the participation of ADP and thromboxane A2. On the other hand, platelet responses were not attenuated by the PAF antagonist BN 52021, signifying that PAF-acether did not play a role in elastase potentiation. At higher concentrations porcine pancreatic elastase exhibits similar effects to neutrophil elastase, demonstrating that the effect of elastase was not unique to the neutrophil protease. While neutrophil elastase failed to alter the ability of cathepsin G to hydrolyze a synthetic chromogenic substrate, preincubation of platelets with elastase increased the apparent affinity of cathepsin G binding to platelets. In contrast to their effect on cathepsin G-induced platelet responses, neither neutrophil nor pancreatic elasatse potentiated aggregation or dense granule release initiated by ADP, PAF-acether, arachidonic acid or U46619, a thromboxane A2 mimetic. Moreover, unlike its effect on cathepsin G, neutrophil elastase inhibited thrombin-induced responses. The current observations demonstrate that elastase can potentiate platelet responses mediated by low concentrations of cathepsin G, suggesting that both enzymes may function synergistically to activate platelets under conditions where neutrophil degranulation occurs.

Trimucytin: A Collagen-Like Aggregating Inducer Isolated from Trimeresurus mucrosquamatus Snake Venom

1993 ◽  
Vol 69 (03) ◽  
pp. 286-292 ◽  
Author(s):  
Che-Ming Teng ◽  
Feng-Nien Ko ◽  
Inn-Ho Tsai ◽  
Man-Ling Hung ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Snake Venom ◽  
Inositol Phosphate ◽  
Shape Change ◽  
Platelet Activating Factor ◽  
Atp Release ◽  
Platelet Membrane ◽  
Thromboxane B2 ◽  
Dependent Manner ◽  
Concentration Dependent Manner

SummaryTrimucytin is a potent platelet aggregation inducer isolated from Trimeresurus mucrosquamatus snake venom. Similar to collagen, trimucytin has a run of (Gly-Pro-X) repeats at the N-terminal amino acids sequence. It induced platelet aggregation, ATP release and thromboxane formation in rabbit platelets in a concentration-dependent manner. The aggregation was not due to released ADP since it was not suppressed by creatine phosphate/creatine phosphokinase. It was not either due to thromboxane A2 formation because indomethacin and BW755C did not have any effect on the aggregation even thromboxane B2 formation was completely abolished by indomethacin. Platelet-activating factor (PAF) was not involved in the aggregation since a PAF antagonist, kadsurenone, did not affect. However, RGD-containing peptide triflavin inhibited the aggregation, but not the release of ATP, of platelets induced by trimucytin. Indomethacin, mepacrine, prostaglandin E1 and tetracaine inhibited the thromboxane B2 formation of platelets caused by collagen and trimucytin. Forskolin and sodium nitroprusside inhibited both platelet aggregation and ATP release, but not the shape change induced by trimucytin. In quin-2 loaded platelets, the rise of intracellular calcium concentration caused by trimucytin was decreased by 12-O-tetradecanoyl phorbol-13 acetate, imipramine, TMB-8 and indomethacin. In the absence of extracellular calcium, both collagen and trimucytin caused no thromboxane B2 formation, but still induced ATP release which was completely blocked by R 59022. Inositol phosphate formation in platelets was markedly enhanced by trimucytin and collagen. MAB1988, an antibody against platelet membrane glycoprotein Ia, inhibited trimucytinand collagen-induced platelet aggregation and ATP release. However, trimucytin did not replace the binding of 125I-labeled MAB1988 to platelets. Platelets pre-exposed to trimucytin were resistant to the second challenge with trimucytin itself or collagen. It is concluded that trimucytin may activate collagen receptors on platelet membrane, and cause aggregation and release mainly through phospholipase C-phosphoinositide pathway.

Influence of Brain Gangliosides on the Formation and Properties of Supported Lipid Bilayers for Binding Kinetics Studies

2018 ◽  
Author(s):  
Luke Jordan ◽  
Nathan Wittenberg
Keyword(s):  
Lipid Bilayers ◽  
Binding Kinetics ◽  
Supported Lipid Bilayers ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Supported Lipid Bilayer ◽  
Head Groups ◽  
Lipid Diffusion ◽  
Kinetics Of ◽  
Brain Gangliosides

This is a comprehensive study of the effects of the four major brain gangliosides (GM1, GD1b, GD1a, and GT1b) on the adsorption and rupture of phospholipid vesicles on SiO2 surfaces for the formation of supported lipid bilayer (SLB) membranes. Using quartz crystal microbalance with dissipation monitoring (QCM-D) we show that gangliosides GD1a and GT1b significantly slow the SLB formation process, whereas GM1 and GD1b have smaller effects. This is likely due to the net ganglioside charge as well as the positions of acidic sugar groups on ganglioside glycan head groups. Data is included that shows calcium can accelerate the formation of ganglioside-rich SLBs. Using fluorescence recovery after photobleaching (FRAP) we also show that the presence of gangliosides significantly reduces lipid diffusion coefficients in SLBs in a concentration-dependent manner. Finally, using QCM-D and GD1a-rich SLB membranes we measure the binding kinetics of an anti-GD1a antibody that has similarities to a monoclonal antibody that is a hallmark of a variant of Guillain-Barre syndrome.

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