Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The capacity of immunoglobulin for intravenous application (IgG-IV) to interact with Fc receptors of human monocytes and macrophages was tested by quantifying the inhibition of phagocytosis of IgG-sensitized erythrocytes. To this end a spectrometric phagocytosis test has been used. When compared with IgG for i.m. use (IgG-IM), all IgG-IV had reduced activity. This reduction was related, in part, to the reduced amount of IgG dimers and polymers in IgG-IV. On a weight basis dimeric IgG and polymeric IgG exerted 6-fold and 14-fold higher activity, respectively, than monomeric IgG. When this difference was corrected for, chemically modified IgG-IV still had significantly reduced inhibitory activity; DEAE-Sephadex-treated IgG and acid-treated IgG had an activity similar to IgG-IM, and PEG-treated IgG showed a slightly reduced activity. Pepsin-treated IgG was greater than 100-fold less active than IgG-IM. The reactivity of IgG-IV with monocyte and macrophage Fc receptors was closely correlated. The most conspicuous differences found were related to the concentration at which IgG was used. Thus, beta-propiolactone-treated IgG and plasmin-treated IgG were found to have significantly reduced activity at concentrations greater than 20 micrograms/ml, but almost normal activity when used at lower concentrations.
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PMID:The capacity of various types of immunoglobulin for intravenous use to interact with Fc receptors of human monocytes and macrophages. 375 58

It has been recognized in the experiments of animals, that high dose of administration of IgG suppresses the immunoglobulin production in vitro, because of masking of antigen determinants. The study evaluated the effect of several gammaglobulin preparations on in vitro immunoglobulin production induced by pokeweed mitogen. And the effect of these preparations was estimated by following system. Mononuclear cells (5 X 10(5)/ml) were incubated (37 degrees C, 5% CO2) in the presence of gammaglobulin preparations (0.01 mg/ml-1.0 mg/ml). On the sixth day of culture, the cells were spun down, washed three times, resuspended in MEM without L-4,5 [3H]-leucine. After 24 hours, supernatants were harvested, and the concentration of immunoglobulin produced by mononuclear cells was analyzed by solid-phase RIA. And the results which have been obtained as follows. PWM induced immunoglobulin production (IgG) was analyzed in the presence of immunoglobulin preparations. Among these preparations, the suppressive effect of ISG was most significant, and the effect was dose dependent. S-sulfonated and PEG-treated preparations also suppressed the IgG production, but not so strong as ISG. In the suppressive effect between S-sulfonation and PEG treatment, no significant difference was found. Pepsin treated preparation had no suppressive effect. Not only IgG production, but also IgA, IgM production were suppressed by the co-culture of ISG, S-sulfonated, and PEG treated IgG. ISG inhibits directly the differentiation of B cells, and also induces the activation of suppressor T cells. ISG was considered to suppress immunoglobulin production in vitro by these both pathways. The suppressor T cells, which are induced by ISG, are radiation resistant, hydrocortisone resistant and same population with OKT 8 positive cells.
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PMID:[The effect of gammaglobulin preparations on in vitro immunoglobulin production induced by pokeweed mitogen]. 620 26

The equilibrium mixture of yeast enolase with substrate, 2-phospho-D-glycerate (2-PGA), and product, phosphoenolpyruvate (P-enolpyruvate), has been crystallized from solutions of poly(ethylene glycol) (PEG) at pH 8.0. Crystals belong to the space group C2 and have unit cell dimensions a = 121.9 A, b = 73.2 A, c = 93.9 A, and beta = 93.3 degrees. The crystals have one dimer per asymmetric unit. Crystals of the equilibrium mixture and of the enolase complex of phosphonoacetohydroxamate (PhAH) are isomorphous, and the structure of the former complex was solved from the coordinates of enolase-(Mg2+)2-PhAH [Wedekind, J. E., Poyner, R. R., Reed, G. H., & Rayment, I. (1994) Biochemistry 33, 9333-9342]. The current crystallographic R-factor is 17.7% for all recorded data (92% complete) to 1.8 A resolution. The electron density map is unambiguous with respect to the positions and liganding of both magnesium ions and with respect to the stereochemistry of substrate/product binding. Both magnesium ions are complexed to functional groups of the substrate/product. The higher affinity Mg2+ coordinates to the carboxylate side chains of Asp 246, Glu 295, and Asp 320, both carboxylate oxygens of the substrate/product, and a water molecule. One of the carboxylate oxygens of the substrate/product also coordinates to the lower affinity Mg2+-thus forming a mu-carboxylato bridge. The other ligands of the second Mg2+ are a phosphoryl oxygen of the substrate/product, two water molecules, and the carbonyl and gamma-oxygens of Ser 39 from the active site loop. The intricate coordination of both magnesium ions to the carboxylate group suggests that both metal ions participate in stabilizing negative charge in the carbanion (aci-carboxylate) intermediate. The epsilon-amino group of Lys 345 is positioned to serve as the base in the forward reaction whereas the carboxylate side chain of Glu 211 is positioned to interact with the 3-OH of 2-PGA. The structure provides a candid view of the catalytic machinery of enolase.
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PMID:A carboxylate oxygen of the substrate bridges the magnesium ions at the active site of enolase: structure of the yeast enzyme complexed with the equilibrium mixture of 2-phosphoglycerate and phosphoenolpyruvate at 1.8 A resolution. 860 83

Adhesion of bacteria at the surface of implanted materials is the first step in microbial infection, leading to post-surgical complications. In order to reduce this adhesion, we show that poly(L-lysine)/poly(L-glutamic acid) (PLL/PGA) multilayers ending by several PLL/PGA-g-PEG bilayers can be used, PGA-g-PEG corresponding to PGA grafted by poly(ethylene glycol). Streaming potential and quartz crystal microbalance-dissipation measurements were used to characterize the buildup of these films. The multilayer films terminated by PGA and PGA-g-PEG were found to adsorb an extremely small amount of serum proteins as compared to a bare silica surface but the PGA ending films do not reduce bacterial adhesion. On the other hand, the adhesion of Escherichia coli bacteria is reduced by 72% on films ending by one (PLL/PGA-g-PEG) bilayer and by 92% for films ending by three (PLL/PGA-g-PEG) bilayers compared to bare substrate. Thus, our results show the ability of PGA-g-PEG to be inserted into multilayer films and to drastically reduce both protein adsorption and bacterial adhesion. This kind of anti-adhesive films represents a new and very simple method to coat any type of biomaterials for protection against bacterial adhesion and therefore limiting its pathological consequences.
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PMID:Polyelectrolyte multilayer films with pegylated polypeptides as a new type of anti-microbial protection for biomaterials. 1474 14

Poly(lactide-co-glycolide) (PLGA), a biocompatible and biodegradable polyester co-polymer of PLA and PGA, has been recognized for its ability to deliver genes. However, gene delivery by PLGA nanoparticles is limited by their negative charge and their poor transport through mucosal barriers. In this study, PLGA nanoparticles were surface modified with cationic chitosan in an effort to improve their gene delivery capability. PLGA nanoparticles were synthesized by emulsion-diffusion-evaporation technique using PVA-chitosan (PLGA1) or PVA-chitosan-PEG (PLGA2) blend as stabilizers. This method is reproducible and produces nanoparticles with hydrodynamic diameter <200 nm. The nanoparticles were characterized by zetasizer, photon correlation spectroscopy and atomic force microscopy. A549 epithelial cells were transfected in vitro with PLGA particles complexed with a reporter plasmid encoding green fluorescent protein. PLGA particles transferred EGFP gene, but were less efficient than the lipofectamine control. The nanoparticles were also tested for their ability to transport across the nasal mucosa in vivo in mice. The results show that both PLGA1 and PLGA2 facilitate gene delivery and expression in vivo with increased efficiency and without causing inflammation, as measured by IL-6. Together, these results indicate that chitosan-modified PLGA nanoparticles have greater potential as gene carriers.
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PMID:Cationic poly(lactide-co-glycolide) nanoparticles as efficient in vivo gene transfection agents. 1565 92

The amidase reaction of trypsin, which is a member of the serine proteinase family, is accelerated by its complexation with block ionomers containing a polycarboxylate block, such as PEG-PAA, PEG-PGA, or PEG-PMA. PEG-PAA and PEG-PGA had similar effects, causing an increase in the k(cat) value and a shift in the pH profile to a lower pH region. On the other hand, PEG-PMA showed not only an increase in the k(cat) value, but also a decrease in the activation energy; however, there was no shift in the pH dependence of the initial reaction rate. Such differences might be induced by the difference in pK(a) values of the polycarboxylate block in block ionomers.
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PMID:Effect of polycarboxylate blocks on the amidase activity of trypsin through complexation with PEG/polycarboxylate block ionomers. 1737 Feb 72

A study of the practical applications of the addition of paramagnetic spin relaxation (PSR) ions to a variety of polymers (PLL, PAA, PGA, PVP, and polysaccharides such as hyaluronic acid, chitosan, mannan, and dextran) in solution (D2O and DMSO-d6) is described. Use of Gd(III), Cu(II), and Mn(II) allows a reduction of up to 500% in the 1H longitudinal relaxation times (T1), and so in the time necessary for recording quantitative NMR spectra (sensitivity enhancement) neither an increase of the spectral line width nor chemical shift changes resulted from addition of any of the PSR agents tested. Selective suppression of the 1H and 13C NMR signals of certain components (low MW molecules and polymers) in the spectrum of a mixture was attained thanks to their different sensitivity [transverse relaxation times (T2)] to Gd(III) (PSR filter). Illustration of this strategy with block copolymers (PGA-g-PEG) and mixtures of polymers and low MW molecules (i.e., lactose-hyaluronic acid, dextran-PAA, PVP-glutamic acid) in 1D and 2D NMR experiments (COSY and HMQC) is presented. In those mixtures where PSR and CPMG filters alone failed in the suppression of certain components (i.e., PVP-mannan-hyaluronic acid) due to their similarity of 1H T2 values and sensitivities to Gd(III), use of the PSR filter in combination with CPMG sequences (PSR-CPMG filter) successfully resulted in the sequential suppression of the components (hyaluronic acid first and then mannan).
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PMID:Paramagnetic NMR relaxation in polymeric matrixes: sensitivity enhancement and selective suppression of embedded species (1H and 13C PSR filter). 1800 45

Prospective biomedical applications of hollow polyelectrolyte microcapsules, for example, as drug delivery systems, require surface modifications that help to escape clearance by the mononuclear phagocytic system (MPS). Layer-by-layer assembled microcapsules that were alternatingly composed of polystyrene sulfonate (PSS) and polyallylamine hydrochloride (PAH) were coated with adlayers of poly(ethylene glycol) (PEG)-grafted poly-L-lysine (PLL-g-PEG) and poly-L-glutamic acid (PGA-g-PEG). Their effects on MPS recognition were studied in primary cell cultures of human monocyte derived dendritic cells and macrophages. PGA-g-PEG coatings had no significant effect on cellular recognition, which may be explained by insufficient PEG density of the adlayer. Contrary, PLL-g-PEG effectively blocked phagocytosis of coated microcapsules. In addition, PLL-g-PEG coatings showed efficient adlayer stability for at least 3 weeks, and PAH/PSS microcapsules did not impair phagocyte viability. Our results demonstrate that layer-by-layer assembled polyelectrolyte microcapsules coated with a PEG-grafted polyelectrolyte, PLL-g-PEG, represent a promising platform for a drug delivery system that escapes fast clearance by the MPS.
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PMID:Stable stealth function for hollow polyelectrolyte microcapsules through a poly(ethylene glycol) grafted polyelectrolyte adlayer. 1807 22

An investigation of encapsulated plasmid DNA release from degradable poly(ethylene glycol)-co-poly(glycolic acid) hydrogels (PEG-co-PGA) is presented. We determined by varying the chemistry of the cross-linker group, significant variations in hydrogel degradation kinetics could be achieved to control the release profiles of plasmid DNA. We prepared three analogues of PEG-co-PGA hydrogels by a photopolymerization process and measured variation in degradation rates by monitoring mechanical properties and release of plasmid DNA. 1H 1D DOSY NMR (one-dimensional diffusion ordered nuclear magnetic resonance spectroscopy) was used to measure conversion of vinyl groups after photocross-linking. Nearly full vinyl conversion was reached after 10 min exposure under ultraviolet light. Gel electrophoresis analysis confirmed that plasmid DNA remained structurally intact after photoencapsulation and release from the gels. This approach provides an additional strategy for controlling the release of biologically active compounds from hydrogels.
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PMID:Influence of cross-linker chemistry on release kinetics of PEG-co-PGA hydrogels. 1849 97

We report the synthesis of covalently stabilized hollow capsules from biodegradable materials using a combination of click chemistry and layer-by-layer (LbL) assembly. The biodegradable polymers poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) were modified with alkyne and azide moieties. Linear film buildup was observed for both materials on planar surfaces and colloidal silica templates. A variation of the assembly conditions, such as an increase in the salt concentration and variations in pH, was shown to increase the individual layer thickness by almost 200%. The biodegradable click capsules were analyzed with optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Capsules were uniform in size and had a regular, spherical shape. They were found to be stable between pH 2 and 11 and showed reversible, pH-responsive shrinking/swelling behavior. We also show that covalently stabilized PLL films can be postfunctionalized by depositing a monolayer of heterobifunctional poly(ethylene glycol) (PEG), which provides low-fouling properties and simultaneously enhances specific protein binding. The responsive, biodegradable click films reported herein are promising for a range of applications in the biomedical field.
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PMID:Low-fouling, biofunctionalized, and biodegradable click capsules. 1899 59


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