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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At least four native plasminogen activators were detected in bovine milk, and two partially purified plasminogen activators were characterized. The plasminogen activators were dissociated from casein proteins by treatments with sulfuric acid and dimethylformamide. The plasminogen activators in the resulting fractions were partially purified with size exclusion, affinity, or metal chelate chromatographic techniques. Molecular weights of the two partially purified plasminogen activators were 47.2 and 30.5 kDa by gel electrophoresis. Size exclusion chromatography gave a molecular weight of 43.2 kDa for the first plasminogen activator. The isoelectric points of the two plasminogen activators were in the pH range 6.2 to 6.7. Because activity was not enhanced by the presence of fibrinogen fragments in a plasminogen activator assay mixture and decreased when human anti-urokinase Ig were added, at least some bovine milk native plasminogen activators appear to be urokinase-type plasminogen activators.
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PMID:Partial purification and characterization of native plasminogen activators from bovine milk. 189 5

The present study documents the effect of the planar, polar differentiation promoter N,N-dimethylformamide (DMF) on urokinase binding to colon carcinoma cells. Exposure of the colon carcinoma cell lines to the agent resulted in enhanced specific binding of radioactive urokinase to all cells tested. Insulin binding to the cells was, however, unaffected by DMF. A DMF exposure period of 45 h was required to observe maximum urokinase binding to two representative cell lines FET and RKO. Optimal stimulation of both cell lines occurred with 0.8% DMF. Scatchard analysis revealed the dissociation constants to be unchanged by the agent with the increased binding of radioactive plasminogen activator reflecting an up-regulation of binding sites. In this regard, the cell line RKO upon exposure to DMF, displayed approx. 700,000 receptors/cell, the highest value published, to date, for any cell line.
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PMID:Modulation of the urokinase receptor in human colon cell lines by N,N-dimethylformamide. 283 92

The effects of maturation inducing agents on the production of plasminogen activator (PA) and plasminogen activator inhibitor (PAI) by the human promyelocytic leukemia cell line HL-60 were examined. PA activity, which was calibrated with a urokinase standard, was 3-6 mU/10(6) cells when measured in supernatants from control cells. This activity increased at least two-fold after dimethylformamide (DMF) or retinoic acid (RA) was added to cell cultures, and as much as ten to thirty-fold when cells were exposed to 12-O-tetradecanoylphorbol-13-acetate (PMA), an agent that induces monocytoid differentiation in HL-60 cells. The PA activity produced by control and induced cells had the same molecular weight as urokinase (UK), and was completely inhibited by antibodies to UK. Cells that were induced with PMA but not with RA or DMF also produced an inhibitor to UK that was identified as PAI-2, the plasminogen activator inhibitor that is produced by monocytes. Because of its dual capacity to produce both UK and PAI, the HL-60 cell line represents a useful model for studies of the fibrinolytic mediators that are generated and released by leukemia cells.
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PMID:Stimulated production of urokinase and plasminogen activator inhibitor-2 by the human promyelocytic leukemia cell line HL-60. 314 93

Treatment of low-metastatic Lewis lung carcinoma cells (P-29) with dimethylsulfoxide (DMSO) in vitro enhanced their lung-colonizing ability. The effects of other highly polar compounds on the lung-colonizing ability of P-29 cells were examined. The following compounds were found to enhance the lung-colonizing ability of the cells: acetamide, N-methylacetamide, N-methylformamide, N,N-dimethylformamide, piperidone and hexamethylphosphoric triamide. Treatment of P-29 cells with DMSO or other polar compounds resulted in increases in activities of degradative enzymes, such as cathepsin B and plasminogen activator. The increases in cathepsin B and plasminogen activator activities were apparent after a 24 h treatment with DMSO and were suppressed by simultaneous treatment with cycloheximide, which suggested that they were due to syntheses of new proteins. DMSO-treated P-29 cells degraded [3H]leucine-labelled subendothelial matrix much more than did untreated cells. P-29 cells treated with DMSO or other polar compounds became attached to culture dishes more rapidly and were more resistant to detachment by trypsin treatment than untreated cells. A significant correlation was found between the degrees of adhesiveness of P-29 cells treated with various polar compounds and their lung-colonizing abilities.
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PMID:Enhancement of lung-colonizing ability of cloned low-metastatic Lewis lung carcinoma cells by treatment with highly polar compounds. 654 Feb 47

Administration to rats of monocrotaline pyrrole (MCTP), a putative metabolite of the pyrrolizidine alkaloid, monocrotaline, causes pulmonary microvascular thrombosis that is associated with vascular remodeling and pulmonary hypertension. It is possible that vascular thrombi contribute to the lesions that occur after MCTP treatment. Since MCTP is toxic to pulmonary endothelial cells and because the pulmonary endothelium is in a unique position to influence procoagulant and fibrinolytic reactions in the lungs, we examined changes in the procoagulant and fibrinolytic properties of cultured pulmonary artery endothelial cells exposed to MCTP to see if they might favor thrombosis. Monolayers of confluent bovine pulmonary arterial endothelial cells received a single administration of MCTP or N,N-dimethylformamide vehicle, and the media or lysates were examined at 4, 24, 48, or 120 hr after treatment. MCTP caused a time-dependent cell detachment and an increase in release of lactate dehydrogenase into culture medium. Although cell numbers decreased dramatically with time, the protein concentration of cell monolayer lysates was unchanged by treatment. MCTP treatment caused no change in the amount of tissue factor activity/micrograms cellular protein in bovine endothelial cell lysates and only a small increase in the activity of Factor V in the culture medium at 120 hr. In addition, the medium from bovine endothelial cells treated with MCTP had a time-dependent increase in the activity of plasminogen activators and a decrease in the activity of plasminogen activator inhibitors. Thus bovine endothelial cells exposed to MCTP in vitro do not produce changes in these procoagulant or fibrinolytic properties that would explain the thrombosis observed in vivo.
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PMID:Procoagulant and fibrinolytic properties of bovine endothelial cells treated with monocrotaline pyrrole. 837 34

Nanocomposites of high molecular poly(D,L-lactide) (PLA) with Ca-deficient hydroxyapatite nanocrystals (d-HAP) were successfully prepared through solvent-cast technique. Such composites are of great importance to make bone-like substitutes as d-HAP nanocrystals have similar composition, morphology and crystal structure as natural apatite crystals. Of all the PLA solvents studied, N,N-dimethylformamide is the best one to disperse d-HAP nanocrystals. The resultant sol is a blue, stable dispersion that could preserve several days with only slight precipitation. The bright-field TEM micrograph shows that d-HAP nanocrystals form homogeneous dispersion in the PLA matrix at a microscopic level. The tensile modulus for PLA/d-HAP nanocomposites increases with d-HAP loading. Theoretical prediction of the modulus has been made by assuming the nanocomposites as short fiber filled systems. The calculated values based on Halpin-Tsai equations show excellent agreement with the experimental results. The yield stress for the nanocomposites has not been undermined by the presence of the nanocrystals. This preservation of strength for PLA/d-HAP nanocomposites may be due to the homogeneous dispersion of d-HAP nanocrystals in the PLA matrix as well as the good interfacial adhesion.
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PMID:Preparation and mechanical properties of nanocomposites of poly(D,L-lactide) with Ca-deficient hydroxyapatite nanocrystals. 1156 92

This article reports on a novel two-step strategy for the coating of cardiovascular stents by strongly adhering biocompatible and biodegradable aliphatic polyesters. First, a precoating of poly(ethylacrylate) (PEA) was electrografted onto the metallic substrate by cathodic reduction of the parent monomer in dimethylformamide (DMF). The electrodeposition of PEA, in a good solvent of it, was confirmed by both Infra-red and Raman spectroscopies. The pendant ester groups of PEA were then chemically reduced into aluminum alkoxides, able to initiate the ring-opening polymerization (ROP) of either D,L-lactide (LA) or epsilon-caprolactone (CL). Growth of biodegradable PLA or PCL coatings from the adhering precoating was confirmed by both Infra-red and Raman spectroscopies, and directly observed by scanning electron microscopy (SEM). This type of coating can act as an anchoring layer for the subsequent casting of drug-loaded polyester films allowing the controlled release of antiproliferative agents for the treatment of in-stent restenosis.
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PMID:Surface modification of metallic cardiovascular stents by strongly adhering aliphatic polyester coatings. 1631 21

Ultrafine poly (D, L-lactide) (PLA) fibers with diameter less than 200 nm produced by electrospinning were studied to obtain tissue restoration resembling extracellular matrix. Scanning electron microscopy was used to observe the fiber morphology. Results showed that the solvent was the critical factor to determine the formation of the electrospun PLA fibers. Compared with acetone, N,N-dimethylformamide (DMF) was a better solvent for PLA to electrospin. Entrance of an organic salt, triethylbenzylammonium chlorate, led to a great increase of the conductivity of PLA/DMF solutions, so that the average fiber diameter of the electrospun PLA fibers decreased dramatically from 500 nm to 100-200 nm. The addition of surfactant, Span-80, did not improve the fiber morphology but formed beaded fiber web.
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PMID:[Electrospinning and morphology of ultrafine poly (D, L-lactide) fibers]. 1642 11

Ultra-fine fibers of poly(vinyl alcohol)/polyethylenimine (PVA/PEI) were prepared by electrospinning of their blend solutions in water. Effects of PVA/PEI mass ratio and the polymer concentration on the fiber morphology were discussed by analysis of scanning electron micrographs. Results showed that uniform ultra-fine fibers could be obtained from an 8% PVA/PEI solution with 75:25 mass ratio. It was supposed that the introduction of PVA could promote electrospinning of PEI by weakening the intermolecular interaction and increasing solution viscosity. A composite membrane of PVA/PEI with poly(D,L-lactide) (PLA) was produced by co-electrospinning simultaneously from the aqueous 8% PVA/PEI (75:25) solution and a 20% PLA solution in N,N-dimethylformamide in two separated syringes. Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy verified the existence of PVA/PEI and PLA in the fibrous membrane. We attempted to incorporate PEI with PLA as ultra-fine fibers to diminish the acidic inflammation caused by biodegradation of PLA. The fibrous composite membrane of PVA/PEI-PLA could provide better biocompatibility and would be used as drug-delivery carriers or tissue-engineering scaffolds.
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PMID:Preparation of PVA/PEI ultra-fine fibers and their composite membrane with PLA by electrospinning. 1689 25

In this study, poly(lactic acid) (PLA) ultrafine fibers have been prepared by electrospinning method using mix-solvent. The results showed that the variation of solvent ratio (N,N-dimethylformamide (DMF)/Dichloromethane (DCM)) could change the surface morphology of PLA nanofibers. By adjusting the solvent ratio, the quercetin release rate from the fiber membranes could be controlled. Furthermore, by adjusting the PLA concentration, the nanofibers without beads could be obtained. After addition of quercetin to polymer solution, the spindle-shaped beads on the fiber disappeared, but surface morphology of the fiber changed little with increase in quercetin dosage, and the release rate of quercetin increased with increase of quercetin dosage.
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PMID:Preparation and release characteristic of quercetin loaded poly(lactic acid) ultrafine fibers. 2177 51


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