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

Macrophages were obtained by peritoneal lavage from untreated mice or from mice which had received either Brewer's thioglycollate broth or a suspension of streptococcus A cell walls intraperitoneally 4 days before. 3 h after harvesting, adherent cells from untreated mice were allowed to phagocytose zymosan, formaldehyde-treated sheep erythrocytes, or latex beads. Phagocytosis was stopped after 1 h and culture was continued for up to 10 days. Phagocytosis of zymosan or sheep erythrocytes triggered the immediate release of lysosomal glycosidases, stimulated the synthesis of cellular lactate dehydrogenase, and induced the delayed production and secretion of plasminogen activator . No such changes were observed upon phagocytosis of latex. Although all three particles used were phagocytosed, only zymosan and sheep erythrocytes stimulated glucose oxidation via the hexose monophosphate shunt. Similar findings were obtained in macrophages elicited with streptococcus A cell walls after zymosan phagocytosis. Thioglycollate-elicited macrophages, however, which were already secreting lysosomal hydrolases and plasminogen activator, could not be activated further by zymosan. The results of this study show that macrophages become activated after phagocytosis of particles that stimulate the activity of their hexose monophosphate shunt. The triggering event appears to be the burst of shunt activity itself or shunt-related biochemical reactions rather than phagocytic uptake per se or particle-dependent complement activation by the alternative pathway. Once initiated, macrophage activation proceeds independently of the intracellular fate of the ingested material .
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PMID:Role of phagocytosis in the activation of macrophages. 72 42

Tumour cells possess the cell surface protease guanidinobenzoatase (GB) which can be located by the fluorescent probe 9-amino acridine (9-AA). Frozen sections and formaldehyde fixed sections of tumour tissue were used to demonstrate the interactions between GB, 9-AA and two protein inhibitors of GB. A cytoplasmic extract from the tumour tissue, and a purified inhibitor of plasminogen activator (PAI-1) were shown to be exchangeable components of the enzyme-inhibitor complex on the fixed tumour cell surfaces. The evidence suggests that GB is functionally very similar to plasminogen activator and that this enzyme can be regulated by protein inhibitors in vivo and also by changes in the redox potential at the cell surface.
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PMID:The inhibitor reacting with a tumour cell surface protease can be exchanged with plasminogen activator inhibitor (PAI-1). 203 70

Primary cultures of corneal epithelial cells from adult albino rabbits were exposed briefly to various concentrations of NaOH and formaldehyde. The release of plasminogen activator from the cells was stimulated or inhibited during a 6-day recovery period. This differential effect was dependent on the chemical concentration and duration of cell recovery. The modulation of plasminogen activator release in the in vitro system would be useful for predicting ocular toxicity of substances.
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PMID:Chemical injury to an in vitro ocular system: differential release of plasminogen activator. 372 Mar 41

Endothelial cell seeding, a promising method to improve the performance of small-diameter vascular grafts, requires a suitable substrate, such as crosslinked collagen. Commonly used crosslinking agents such as glutaraldehyde and formaldehyde cause, however, cytotoxic reactions and thereby hamper endothelialization of currently available collagen-coated vascular graft materials. The aim of this study was to investigate the effects of an alternative method for crosslinking of collagen, using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) in combination with N-hydroxysuccinimide (NHS), on various cellular functions of human umbilical vein endothelial cells (HUVECs) in vitro. Compared to non-crosslinked type I collagen, proliferation of seeded endothelial cells was significantly increased on EDC/NHS-crosslinked collagen. Furthermore, higher cell numbers were found with increasing crosslink densities. Neither the morphology of the cells nor the secretion of prostacyclin (PGI2), von Willebrand factor (vWF), tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) was affected by the crosslink density of the collagen substrate. Therefore, EDC/NHS-crosslinked collagen is candidate substrate for in vivo application such as endothelial cell seeding of collagen-coated vascular grafts.
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PMID:Endothelial cell seeding on crosslinked collagen: effects of crosslinking on endothelial cell proliferation and functional parameters. 1095 8

A formaldehyde-mediated aggregation pathway (FMAP) has been shown to be primarily responsible for the solid-state aggregation of lyophilized formalinized protein antigens [e.g., tetanus toxoid (TT) and formalinized bovine serum albumin (f-BSA)] in the presence of moisture and physiological temperature. Coincorporation of the formaldehyde-interacting amino acid, histidine, strongly inhibits the FMAP. The purpose of this study was to test whether previous solid-state data are applicable toward the stabilization of formalinized antigens encapsulated in poly(lactide-co-glycolide) (PLGA)-based microspheres. Formaldehyde-treated bovine serum albumin (f-BSA) and BSA were selected as a model formalinized protein antigen and a nonformalinized control, respectively. As in the solid state, we found that the FMAP was dominant in the aggregation of f-BSA encapsulated in PLGA 50/50 microspheres, whereas the aggregation mechanism of encapsulated BSA was mostly converted from thiol-disulfide interchange to an acid-catalyzed noncovalent pathway. The lack of noncovalent aggregation in encapsulated f-BSA could be explained by its higher thermodynamic stability after formalinization, which inhibits protein unfolding. Targeting the FMAP, coencapsulation of histidine and trehalose successfully inhibited the aggregation of f-BSA in microspheres. By combining the use of an optimized oil-in-oil (o/o) encapsulation method, coencapsulation of histidine and trehalose, and use of low-acid-content poly(D,L-lactide) (PLA) and poly(ethylene glycol) (PEG) blends, a 2-month continuous release of f-BSA was achieved with the absence of aggregation.
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PMID:Stabilization of a model formalinized protein antigen encapsulated in poly(lactide-co-glycolide)-based microspheres. 1174 14

Bone substitutes have been used for the treatment of bone defects. The objective of this study was to ultrastructurally evaluate the healing pattern of bone defects filled with a copolymer of polylactic/polyglycolic acid (FisiograftR) at a time point in which it is expected to be only partially degraded, with the purpose to ultrastructurally analyze how the bone is forming around the grafting material. Three 5-mm-diameter bone defects were created in each tibia from 5 rabbits (average weight 2.5 kg) in which the material was randomly implanted. Animals were sacrificed 30 days after surgery and the 30 bone defects were fixed in 2% glutaraldehyde-2.5% formaldehyde, under microwave irradiation, decalcified in EDTA, embedded in Spurr resin, and examined in a Jeol 1010 TEM. All the bone defects were filled with connective tissue, interspersed with different amounts of the filling material and newly formed bone trabeculae. In areas where the degrading copolymer was present in small amounts, newly formed bone matrix was detected; it was deposited by osteoblast-like cells in close relation to the copolymer. In areas where the degrading copolymer formed accumulates, an amorphous multilayered material was identified between the connective tissue and the copolymer. In summary, the copolymer of PLA/PGA studied appears to be an osteoconductive material when it is used to fill bone defects.
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PMID:Ultrastructure of bone healing in defects grafted with a copolymer of polylactic/polyglycolic acids. 1594 3

A series of new alkoxy-amino-bis(phenols) (H2L 1-6) has been synthesized by Mannich condensations of substituted phenols, formaldehyde, and amino ethers or diamines. The coordination properties of these dianionic ligands towards yttrium, lanthanum, and neodymium have been studied. The resulting Group 3 metal complexes have been used as initiators for the ring-opening polymerization of rac-lactide to provide poly(lactic acid)s (PLAs). The polymerizations are living, as evidenced by the narrow polydispersities of the isolated polymers, together with the linear natures of number average molecular weight versus conversion plots and monomer-to-catalyst ratios. Complex [Y(L6){N(SiHMe2)2}(THF)] (17) polymerized rac-lactide to heterotactic PLA (Pr = 0.90 at 20 degrees C) and meso-lactide to syndiotactic PLA (Pr = 0.75 at 20 degrees C). The in situ formation of [Y(L6)(OiPr)(THF)] (18) from 17 and 2-propanol resulted in narrower molecular weight distributions (PDI = 1.06). With complex 18, highly heterotactic PLAs with narrow molecular weight distributions were obtained with high activities and productivities at room temperature. The natures of the ligand substituents were shown to have a significant influence on the degree of control of the polymerizations, and in particular on the tacticity of the polymer.
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PMID:Ring-opening polymerization of lactide with group 3 metal complexes supported by dianionic alkoxy-amino-bisphenolate ligands: combining high activity, productivity, and selectivity. 1622 8

The antiinflammatory effect of the aqueous leaf extract of Byrsocarpus coccineus was evaluated using the carrageenan and egg albumin induced rat paw edema, xylene induced mouse ear edema and formaldehyde induced arthritis inflammation tests. The extract administered orally at doses of 50, 100, 200 and 400 mg/kg b.w produced a significant (P<0.05) dose dependent inhibition of edema formation in all four methods used. The results obtained suggest that the aqueous leaf extract of B. coccineus is endowed with effective antiinflammatory activity mediated via either inhibition of phospholipase A(2) (PLA(2)) activity or cyclooxygenase cascade and by blocking the release of vasoactive substances (histamine, serotonin and kinins). These findings seem to justify the use of the plant in traditional African medicine in the treatment of inflammation, including arthritic conditions.
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PMID:Antiinflammatory activity of the aqueous leaf extract of Byrsocarpus coccineus. 1711 72

The interactions of post-culture treatments reagents used for fixing, lysing and cell quantification on poly(lactide-co-glycolide) (PLGA) flat sheet membrane scaffolds are presented. Lysing with Alkaline buffer solution/Triton X-100/MilliQ water (ATM) and fixing with 10% Neutral Buffered Formalin (10% NBF) had no affect on membrane structure while fixing with 95% ethanol caused smoothing of the surface, shrinkage and a reduction in surface area of 55, 48 and 33, for 100:0, 75:25 and 50:50 (PLA:PGA), respectively. PicoGreen assay was selected for cell (560pZIPv.neo) quantification since the background noise would not affect readings for cell numbers over 3,000 cells/cm(2), while the background reading was too high for MTT and Methylene Blue (MB). MB at 0.5% (w/v) was, however, deemed suitable for visualising cell morphology on the membranes. Furthermore ATM buffer was suitable for the PicoGreen assay, which allows the same samples to be used for quantification of alkaline phosphatase activity.
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PMID:Post-culture treatment protocols for PLGA membrane scaffolds. 1982 Oct 75

Applications of poly(l-lactide) (PLA) and poly(d,l-lactide-co-glycolide) (PLGA) microspheres are widely used in the biomedical and pharmaceutical fields. The effects of PLA/PLGA on microsphere properties when using conventional particulate preparation methods are not easily defined due to the uncontrollable particle size and size distribution. This study was aimed to synthesize uniform PLA and PLGA microspheres using a phenol formaldehyde resin-based microfluidic chip, which has the advantage of being solvent-resistant, flexible, and is readily disassembled for cleaning. The proposed chip can rapidly fabricate reproducible PLA and PLGA microspheres. Uniform emulsion droplets can be achieved by hydrodynamic flow focusing. After solvent evaporation, the free-flowing PLA and PLGA microspheres have a high level of morphological uniformity and size, allowing for a clear comparison of material effects. The results indicate that the sizes of the PLA and PLGA microspheres for the various flow rates of dispersed/continuous phases are very similar. The PLA/PLGA materials do not have a significant effect on particle size, but the particle surface indicates a different morphology. The result of the cytotoxicity evaluation shows no difference between PLA and PLGA and ensures the biocompatibility of both prepared PLA and PLGA microspheres for biomedical and pharmaceutical applications in the future.
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PMID:Synthesis of uniform poly(d,l-lactide) and poly(d,l-lactide-co-glycolide) microspheres using a microfluidic chip for comparison. 2385 79


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