Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies in purified systems have demonstrated that fibrin structure influences the rate of conversion of plasminogen to plasmin by t-PA as well as the rate of plasmin-mediated clot digestion. The present study extended these observations to a plasma system in which fibrin structure was altered by varying the thrombin concentration, varying the plasma ionic strength, or by adding dextran 40. The effect of fibrin structure on the rate of fibrinolysis was assessed by adding plasminogen activators (t-PA or urokinase (UK)) either before or after clot formation. Gel formation and dissolution were monitored optically (turbidity) and isotopically (125I-fibrinogen). Clots formed under conditions of high ionic strength and/or high thrombin concentration were composed of thin fibrin fibres that dissolved slowly. Clots formed at lower ionic strengths, at lower thrombin concentrations or in the presence of dextran were composed of thicker fibres and dissolved more rapidly. The difference in fibrinolytic rate between thin and thick fibres was noted when t-PA or UK was added before or after clot formation. These data indicate that even in a plasma milieu fibre diameter is a factor in determining fibrinolytic rate induced by either UK or t-PA. The method by which fibre diameter is altered does not influence the conclusion that fibrinolytic rate is increased with increasing diameter.
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PMID:Effect of fibrin structure on plasmin-mediated dissolution of plasma clots. 757

The primary structure of the major N-linked carbohydrate chains attached to Asn302 of urinary-type plasminogen activator (urokinase) have been determined. Urokinase was completely deglycosylated with peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase F from Flavobacterium meningosepticum. Released oligosaccharides were separated from the remaining protein using gel-permeation chromatography on Bio-Gel P-100, and then on Bio-Gel P-6. Fractionation of the oligosaccharides was achieved by a combination of FPLC anion-exchange chromatography on Mono Q HR 5/5 and amine-adsorption HPLC on LiChrospher 100-NH2. Analysis by 1H-NMR spectroscopy demonstrated that the collection of N-glycans comprises di-, tri-, and tri'-antennary structures. The glycans contain predominantly GalNAc beta 1-4GlcNAc beta instead of Gal beta 1-4GlcNAc beta elements. The GalNAc residue is mainly sulfated at O4, or to a lesser extent it bears N-acetylneuraminic acid at O6; alternatively the GlcNAc residue can be fucosylated at O3. The major component, which accounts for more than 30 mol/100 mol of the total oligosaccharide pool, consists of an (alpha 1-6)-fucosylated diantennary N-linked carbohydrate chain with (SO4-)-4GalNAc beta 1-4GlcNAc beta 1-2 antennae.
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PMID:The major N-linked carbohydrate chains from human urokinase. The occurrence of 4-O-sulfated, (alpha 2-6)-sialylated or (alpha 1-3)-fucosylated N-acetylgalactosamine(beta 1-4)-N-acetylglucosamine elements. 773 45

A recent report described a thrombin inhibitory activity in the soluble fraction of human placenta and the cytosolic fraction of K562 cells. Isolation and characterization of the functionally inactive 35-38-kDa placental form of this protein revealed that it was a novel serine proteinase inhibitor (Coughlin, P. B., Tetaz, T., and Salem, H. H. (1993) J. Biol. Chem. 268, 9541-9547). In the present study, we observed a 67-kDa sodium dodecyl sulfate (SDS)-stable complex when 125I-thrombin was incubated with the cytosolic fraction of a monkey kidney epithelial cell line, BSC-1. This complex was not observed in either the particulate cell fraction extracted with 0.2% Triton X-100 or medium conditioned by cells, suggesting that the thrombin-complexing factor is confined to the cytoplasm. The cytoplasmic antithrombin activity was purified to apparent homogeneity from the cytosol of BSC-1 cells previously pulsed with [35S]methionine by a combination of heparin-agarose chromatography, Mono Q fast protein liquid chromatography, and anhydrotrypsin-Affi-Gel 10 affinity chromatography. Analysis of the affinity-purified preparation by SDS-polyacrylamide gel electrophoresis and fluorography revealed a single protein with an apparent molecular mass of 38 kDa. The purified 38-kDa protein inhibited the amidolytic activities of thrombin, trypsin, urokinase, and factor Xa but not that of elastase. Incubation of the 38-kDa protein with excess thrombin identified approximately 60% of the labeled 38-kDa protein in an SDS-stable 67-kDa complex. The purified 38-kDa inhibitor was cleaved with cyanogen bromide and the isolated peptides subjected to microsequencing. Amino acid sequence obtained for a region within this protein exhibited significant homology with human antithrombin III and plasminogen activator inhibitors 1 and 2. This homologous peptide contained the full complement of residues designated as highly conserved in helix F of the greater serine proteinase inhibitor superfamily. In addition, an internal sequence of GGGGDIHQGF was found in the monkey cytoplasmic inhibitor, which is identical to that reported for an internal sequence of the human placental inhibitor. These findings confirm the existence of a novel cytoplasmic serine proteinase inhibitor in mammalian cells and provide additional details of its molecular properties. The physiological function of this novel serine proteinase inhibitor in cytoplasm is unknown.
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PMID:Isolation and characterization of an intracellular serine proteinase inhibitor from a monkey kidney epithelial cell line. 840 7

Five molecular weight grades of poly(DL-lactic acid) (PLA) were incorporated as organic and aqueous pseudolatex binders into matrix tablet formulations containing microcrystalline cellulose and the model drug theophylline. The tablets were thermally treated to temperatures above and below the glass transition temperature (Tg) of the PLA. The results of the dissolution studies showed that thermally treating the tablets to temperatures above the Tg of the PLA significantly retarded the matrix drug release compared to tablets which were not thermally treated. The retardation in drug release could be attributed to a stronger compact and a more efficient redistribution of polymer throughout the tablet matrix, based on fundamental principles of annealing. In addition, results from tablet index testing supported the dissolution results. The bonding index of the compact formulations increased after thermal treatment above the Tg of the PLA. Gel permeation chromatography and differential scanning calorimetry studies demonstrated that thermal treatment had no significant effect on the molecular weight and the glass transition temperature of (PLA) alone and in combination with other components of the tablet formulation.
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PMID:The influence of thermal treatment on the physical-mechanical and dissolution properties of tablets containing poly(DL-lactic acid). 848 36

The glycosylation of tissue plasminogen activator (t-PA) obtained from the Bowes melanoma cell line was re-examined using methods of serial lectin affinity chromatography coupled with Bio-Gel P-4 gel filtration chromatography and exoglycosidase sequencing. This study clarified an earlier discrepancy in the literature and confirmed that the major complex N-linked glycans on Bowes t-PA that carry sialic acid as their sole charged group are bi-antennary, core fucosylated, with terminal N-acetylgalactosamine residues. We also report the characterization of a series of related and previously unidentified sialylated glycans. Further we show that Bowes t-PA expresses glucuronic acid/sulphate containing N-linked glycans and is recognized by anti-carbohydrate L2/HNK-1 monoclonal antibodies. The presence on Bowes t-PA of glycans associated primarily with the nervous system is consistent with its expression in a cell line of neuroectodermal origin.
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PMID:The glycosylation of Bowes melanoma tissue plasminogen activator: lectin mapping, reaction with anti-L2/HNK-1 antibodies and the presence of sulphated/glucuronic acid containing glycans. 868 84

The present paper shows that conformationally changed fibrinogen can expose the sites A alpha-(148-160) and gamma-(312-324) involved in stimulation of the tissue-type plasminogen activator (t-PA)-catalysed plasminogen activation. The exposure of the stimulating sites was determined by ELISA using mABs directed to these sites, and was shown to coincide with stimulation of t-PA-catalysed plasminogen activation as assessed in an assay using a chromogenic substrate for plasmin. Gel permeation chromatography of fibrinogen conformationally changed by heat (46.5 degrees C for 25 min) demonstrated the presence of both aggregated and monomeric fibrinogen. The aggregated fibrinogen, but not the monomeric fibrinogen, has exposed the epitopes A alpha-(148-160) and gamma-(312-324) involved in t-PA-stimulation. Fibrinogen subjected to heat in the presence of 3 mM of the tetrapeptide GPRP neither aggregates nor exposes the rate-enhancing sites. Thus, aggregation and exposure of t-PA-stimulating sites in fibrinogen seem to be related phenomena, and it is tempting to believe that the exposure of stimulating sites is a consequence of the conformational changes that occur during aggregation, or self-association. Fibrin monomers kept in a monomeric state by a final GPRP concentration of 3 mM do not expose the epitopes A alpha-(148-160) and gamma-(312-324) involved in t-PA-stimulation, whereas dilution of GPRP to a concentration that is not longer anti-polymerizing, results in exposure of these sites. Consequently, the exposure of t-PA-stimulating sites in fibrin as well is due to the conformational changes that occur during self-association.
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PMID:Aggregated, conformationally changed fibrinogen exposes the stimulating sites for t-PA-catalysed plasminogen activation. 881 85

The effect of processing techniques on the molecular weight of the polymer in biodegradable microspheres of poly(dl-lactic acid) (PLA) and poly(dl-lactic-co-glycolic acid) (PLGA) was investigated. Multiphase microspheres were produced by conventional agitation, potentiometric dispersion, or sonication. Gel permeation chromatography was used to determine the molecular weight of the polymer before and after processing. Polymer in microspheres of PLA produced by sonication experienced a 21% decrease in molecular weight of the polymer after 90 s of sonication, while microspheres made by potentiometric dispersion or mechanical agitation exhibited insignificant changes in molecular weight. Microspheres produced by potentiometric dispersion were found to have a more narrow particle size distribution compared to the other methods. A decrease in the internal diameter of the infusion tube used to produce multiphase microspheres by the potentiometric dispersion method was found to decrease the mean particle size of the resultant microspheres. Two surfactants were investigated at varied levels for utilization in the continuous phase, and particle size analysis revealed that increased surfactant levels caused an increase in the mean particle size of microspheres containing BSA produced by potentiometric dispersion. This phenomenon was attributed to an increase in conductivity of the continuous phase as the surfactant level was increased.
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PMID:Properties of multiphase microspheres of poly(dl-lactic acid) or poly(dl-lactic-co-glycolic acid) produced by mechanical agitation, sonication, or potentiometric dispersion. 893 52

Composting of extruded poly(lactic acid) (PLA) in combination with pre-composted yard waste in a laboratory composting system was studied. Yard waste and PLA mixtures containing 0%, 10%, or 30% PLA (dry weight basis) were placed in composting vessels for four weeks. Exhaust gases were analyzed for carbon dioxide concentration twice per week. After the first week, significantly greater (P < 0.05) amounts of carbon dioxide were generated in vessels with 10% or 30% PLA than in control (0% PLA) vessels. Data indicated that microbial degradation of PLA occurred. There was no significant difference (P > 0.05) in carbon dioxide emission between 10% and 30% PLA mixtures. Compost pH dropped (from 6.0 to 4.0) after 4 weeks of composting for 30% PLA, but remained unchanged (6.3) for 0% or 10% PLA. Most likely, in the case of 30% PLA, substantial chemical hydrolysis and lactic acid generation lowered the compost pH. The lowered pH likely suppressed microbial activity, thus explaining the lack of difference in carbon dioxide emissions between 10% and 30% PLA mixtures. Gel permeation chromatography showed a notable decrease in PLA molecular weight as a result of composting. It was demonstrated that PLA can be efficiently composted when added in small amounts (<30% by weight) to pre-composted yard waste.
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PMID:Laboratory composting of extruded poly(lactic acid) sheets. 1131 11

Accidental skin contact with the Lonomia caterpillar bristles causes a severe hemorrhagic syndrome. While fibrinolytic activation is considered to be the main cause of hemorrhage in Lonomia achelous envenomation, a consumptive coagulopathy was found to be a major component involved in the bleeding complications observed in patients envenomed by contact with Lonomia obliqua. Although we have previously observed that in L. obliqua envenomations, fibrinolysis activation appeared to be secondary to coagulation system activation, there are no reports regarding the ability of L. obliqua venom to activate directly fibrinolytic pathways. We examined the action of L. obliqua crude bristles extract (LOCBE) on several fibrinolytic system components. We demonstrated that LOCBE degraded the A-alpha fibrinogen chain only at high concentrations and after long incubation times. Under these conditions, LOCBE also induced prolongation of the fibrinogen clotting time, but no clot lysis was observed before 24 h. LOCBE did not contain t-PA- or u-PA-like activities. Gel filtration and SDS-PAGE showed that LOCBE did not induce FXIII digestion. In addition, no FXIII activity inhibition was detected by dansylcadaverin method. FXIII levels remained unchanged when FXIII was measured in fibrinogen-depleted LOCBE-treated rat plasma, suggesting that the observed 50% FXIII reduction in rats was related to consumption. In conclusion, our results clearly demonstrated that LOCBE did not display either FXIII inhibition or degradation nor fibrinolytic activity. Furthermore, although proteolytic activity on Aalpha fibrinogen chain was observed, cross-linked fibrin was not affected by LOCBE.
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PMID:Lonomia obliqua venom action on fibrinolytic system. 1501 81

The biocompatibility and biodegradation rate of component materials are critical when designing a drug-delivery device. The degradation products and rate of degradation may play important roles in determining the local cellular response to the implanted material. In this study, we investigated the biocompatibility and relative biodegradation rates of PLA, PGA and two poly(lactic-co-glycolic acid) (PLGA) polymers of 50:50 mol ratio, thin-film component materials of a drug-delivery microchip developed in our laboratory. The in vivo biocompatibility and both in vivo and in vitro degradation of these materials were characterized using several techniques. Total leukocyte concentration measurements showed normal acute and chronic inflammatory responses to the PGA and low-molecular-weight PLGA that resolved by 21 days, while the normal inflammatory responses to the PLA and high-molecular-weight PLGA were resolved but at slower rates up to 21 days. These results were paralleled by thickness measurements of fibrous capsules surrounding the implants, which showed greater maturation of the capsules for the more rapidly degrading materials after 21 days, but less mature capsules of sustained thicknesses for the PLA and high-molecular-weight PLGA up to 49 days. Gel-permeation chromatography of residual polymer samples confirmed classification of the materials as rapidly or slowly degrading. These materials showed thinner fibrous capsules than have been reported for other materials by our laboratory and have suitable biocompatibility and biodegradation rates for an implantable drug-delivery device.
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PMID:Differential degradation rates in vivo and in vitro of biocompatible poly(lactic acid) and poly(glycolic acid) homo- and co-polymers for a polymeric drug-delivery microchip. 1555 50


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