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)

Tissue-type plasminogen activator (tPA) is an endothelium-derived vasoactive substance which is released to the blood stream by exercise, blood occlusion, and desmopressin (DDAVP). The increased capacity of the plasma tPA level raised by these factors is thought to reflect in vivo endothelial function. On the other hand, endothelial dysfunction has been reported in patients with hypercholesteremia as well as in those with diabetes mellitus. Therefore, diabetic patients with hypercholesteremia were administered 5 mg of simvastatin daily for one month and plasma tPA responses evoked by DDAVP were examined before and after treatment for hypercholesteremia. While the treatment of simvastatin for one month significantly reduced serum cholesterol levels from 257 +/- 12 mg to 206 +/- 10 mg (no change in HbA1c was observed during the study), plasma tPA levels and % delta vWF (von Willebrand factor) following DDAVP infusion significantly increased from 11.4 +/- 1.2 ng/ml to 13.4 +/- 1.4 ng/ml and from 69.3 +/- 23.4% to 126.5 +/- 47.4%, respectively. However, neither increase in plasma levels of guanosine 3', 5'-cyclic monophosphate (cGMP) nor change in the depressive response of blood pressure was observed following DDAVP infusion after the treatment of simvastatin. In addition, no change in urinary albumin excretion rate was observed with the treatment of hypercholesteremia. Therefore, it was suggested that improvement in hypercholesteremia may ameliorate vascular endothelial dysfunction in diabetic patients with hypercholesteremia and that hypercholesteremia may enhance endothelial dysfunction in these patients.
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PMID:[Effect of hypercholesteremia on vascular endothelial function and albumin excretion rate in patients with diabetes mellitus]. 895 5

The physiological and pathophysiological state of tissues determines the exudation of plasma proteins, hemostasis, and fibrinolysis, i.e., inflammation, injury, and malignancy. The physiological controls of extravascular fibrinolysis ultimately rest on a balance between generation of the fibrinolytic enzyme(s), i.e., plasmin, elastase, cathepsins, etc., and inhibitors of the fibrinolytic enzyme(s), i.e., plasminogen activator inhibitors, alpha-2 plasmin inhibitor, alpha 1-protease inhibitors, etc. Moreover, it is the structural modification of fibrin that determines its stability toward proteolytic enzymes and physical duress. The structural modification of fibrin involves factor XIIIa-mediated cross-linking of interfibrin chains and alpha 2-plasmin inhibitor to fibrin. In turn, there are a number of agents that influence factor XIIIa catalytic activity (e.g., sulfhydryl agents, albumin, erythrocytes). The two key proenzymes, factor XIII and plasminogen, are tightly bound with the circulating fibrinogen molecules. Such high selective affinity for fibrin(ogen) provides the reaction specificity in a complex tissue fluid milieu and governs the kinetics of fibrinolysis. Any agents that interfere with such binding reactions, e.g., autoantibodies, may also affect the fibrinolytic reactions. Understanding these unique biochemical controls of factors involved in fibrinolysis may provide an insight into the complex regulatory process of extravascular fibrinolysis.
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PMID:Factors that control extravascular fibrinolysis. 912 12

Activation of covalently intact plasminogen by tissue-type plasminogen activator (tPA) is facilitated by a majority of proteins subjected to denaturing conditions. Except for heat-denatured apoferritin, the denatured proteins examined require partial proteolysis by plasmin for cofactor activity. The same proteins in their native state are resistant to proteolysis with plasmin and develop no activity. Denatured preparations of apoferritin, antithrombin, alpha1-protease inhibitor, alpha2-macroglobulin, and albumin also accelerate des(1-77)-plasminogen activation by tPA. The rate enhancements are comparable with that of the fibrin(ogen) fragments on a w/w basis. The cofactor activities are inhibited by 6-aminohexanoate and inactivated by pepsin. Analysis of heat-denatured apoferritin and albumin preparations by ultracentrifugation and gel chromatography indicates that cofactor is associated predominately with aggregates, which have binding capacity for both tPA and zymogen. Heat-denatured albumin pretreated with plasmin decreases K(M) and increases k(cat) for both intact plasminogen and des(1-77)-plasminogen activation by tPA, yielding catalytic efficiencies in excess of 8 x 10(3) M(-1) s(-1) and 2 x 10(4) M(-1) s(-1), respectively. Because of enhanced plasmin-catalyzed proteolysis of plasminogen to des(1-77)-plasminogen, activation by urokinase-type plasminogen activator is also facilitated by denatured proteins; activation of des(1-77)-plasminogen is not affected. It is concluded that denatured proteins serve as both cofactors and substrates in the fibrinolytic system, and that enhancement of plasminogen activation by denatured proteins is mechanistically indistinguishable from that observed with fibrin.
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PMID:Denatured proteins as cofactors for plasminogen activation. 926 48

We measured the plasma levels of fibrinogen, D-dimer, thrombin-antithrombin complex (TAT), plasmin-plasmin inhibitor complex (PPIC), soluble fibrin monomer (SFM), tissue-type plasminogen activator (t-PA) and thrombomodulin (TM) in patients with non-insulin-dependent diabetes mellitus (NIDDM). There were no significant differences in the hemostatic parameters between the 77 patients with NIDDM and healthy control subjects, although the plasma levels of fibrinogen, D-dimer, TAT, and PPIC in the NIDDM patients were slightly higher than those in the healthy controls. Among the NIDDM patients divided into three groups by the urinary albumin excretion (UAE) level, there was no significant difference in age or sex among the normo-, micro-, and macroalbuminuria groups, and the HbA1C level in the micro- and macroalbuminuria groups were slightly higher than those in the normoalbuminuria group. There was no significant difference in activated partial thromboplastin time, prothrombin time, fibrinogen, TAT, PPIC, D-dimer, or t-PA among these three groups. The plasma SFM and TM levels in the macroalbuminuria group were significantly higher than those in the normo- and microalbuminuria groups. The relationships between HbA1C and the hemostatic parameters were poor, but the plasma TM and SFM levels were significantly correlated with the urine albumin index.
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PMID:Increased soluble fibrin monomer and soluble thrombomodulin levels in non-insulin-dependent diabetes mellitus. 928 95

A 5.25-year-old male Yorkshire Terrier was evaluated for suspected thrombosis of the distal portion of the aorta following protein-losing enteropathy. Hind limb paralysis was evident, extremities were hypothermic, and femoral pulses were not palpable. A thrombus was found in the distal portion of the aorta using Doppler ultrasonography. Enteropathy-induced loss of albumin and antithrombin III was the suspected cause of hypercoagulability in this dog. Alteplase, a recombinant tissue-plasminogen activator, was used to recanalize the distal portion of the aorta without inducing clinically evident systemic fibrinogenolysis. Alteplase is a fibrin-specific activator of plasminogen and may be safer and more efficacious than conventional streptokinase treatment. Current information on use in thromboembolic disease in human beings suggests that administration of alteplase as a bolus leads to earlier arterial patency and reduced risk of hemorrhage.
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PMID:Use of recombinant tissue-plasminogen activator for aortic thrombolysis in a hypoproteinemic dog. 949 Nov 62

The irreversible proteinase inhibitor Pefabloc (4-[2-aminoethyl] benzenesulfonyl fluoride) inactivates LDL-catalyzed hydrolysis of the short-chain fluorescent phospholipid C6-NBD-PC (1-acyl-2-(N-4-nitrobenzo-2-oxa-1,3-diazole)-aminocaproyl phosphatidylcholine). The dose-dependence of this inactivation is similar to that obtained previously for the inhibitory effect of Pefabloc on the hydrolysis of platelet activating factor (PAF) by the LDL-associated PAF acetylhydrolase (PAF-AH), in agreement with the notion that the hydrolysis of C6-NBD-PC and PAF is catalyzed by the same enzyme (LDL-associated phospholipase A; LDL-PLA). This conclusion is also supported by the finding that hydrolysis of C6-NBD-PC by LDL becomes inactivated by LDL oxidation only at late stages of the oxidation, similar to the effect of oxidation on the hydrolysis of PAF by the LDL-associated PAF-AH. Under conditions of complete inactivation of this enzyme towards C6-NBD-PC, the kinetics of lipid peroxidation, induced either by copper ions or by the free radical generator AAPH at varying doses of the prooxidant, was similar to that observed when the PLA was active (i.e., in the absence of Pefabloc). Hence, LDL-associated PLA (PAF-AH) does not protect LDL lipids from peroxidation. Similar results were obtained with fractionated LDL in albumin-containing buffer and for non-fractionated serum, in which copper-induced peroxidation was also not influenced by inactivation of the enzyme responsible for hydrolysis of C6-NBD-PC. Phospholipolysis of short chain phospholipids by LDL-PLA may still play a protective role against the toxic effects of oxidized phospholipids by reducing their internalization into cells (Schmitt et al. 1995).
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PMID:LDL-associated phospholipase A does not protect LDL against lipid peroxidation in vitro. 962 86

Biodegradable particulate systems have been considered as parenteral drug delivery systems. The adsorption of plasma proteins on micro- and nanoparticles is determined by the surface properties and may, in turn, strongly influence the biocompatibility and biodistribution of both carriers. In the present study the influence of the polymer composition and the production method of microspheres on the in vitro plasma protein adsorption were investigated using two-dimensional electrophoresis (2-DE). Microparticles were prepared from poly(l-lactide) (l-PLA), poly(d,l-lactide-co-glycolide) (PLGA), and ABA triblock copolymers containing hydrophilic poly(oxyethylene) (B-blocks) domains connected to hydrophobic polyesters (A-blocks). Two different microencapsulation methods were employed, namely the w/o/w emulsion solvent evaporation method and the spray-drying technique. It could be demonstrated that the polymer composition and, especially, the encapsulation technique, influenced the interactions with plasma proteins significantly. For example, the percentages of several apolipoproteins in the plasma protein adsorption patterns of spray-dried PLGA- and l-PLA-particles were distinctly higher when compared to the adsorption patterns of the particles produced by the w/o/w-technique. Some adsorbed proteins were found to be characteristic or even specific for particles produced by the same method or consisting of identical polymers. Polyvinyl alcohol used as stabilizer in the w/o/w-technique may decisively influence the surface properties relevant for protein adsorption. The plasma protein adsorption on particles composed of ABA copolymers was drastically reduced when compared to microspheres made from pure polyesters. The adsorption patterns of ABA-particles were dominated by albumin. The plasma protein adsorption patterns detected on the different microspheres are likely to affect their in vivo performance as parenteral drug delivery systems.
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PMID:Plasma protein adsorption on biodegradable microspheres consisting of poly(D,L-lactide-co-glycolide), poly(L-lactide) or ABA triblock copolymers containing poly(oxyethylene). Influence of production method and polymer composition. 979 26

The feasibility of biodegradable polyester microspheres (MS) for single injection vaccines will greatly depend on the toxoid stability within the MS exposed to in vivo conditions. This study examined the effects of polymer type and co-encapsulated additives on diphtheria (Dtxd) and tetanus (Ttxd) toxoid entrapment and stability. The co-encapsulated stabilizers influenced significantly the entrapment of Dtxd and Ttxd in PLA/PLGA MS. Typically, 5% BSA or trehalose decreased the amount of Dtxd entrapped in spray-dried MS, whereas BSA increased the entrapment in coacervated MS. Further, the entrapment of Dtxd decreased as a function of polymer hydrophobicity in spray-dried MS. Without additives, approx. 64, 43 and 16% entrapment efficiency of ELISA-reactive antigen was obtained for 14-17 kDa PLGA 50:50, PLGA 75:25 and PLA, respectively. The novel end-group stearylated 1-PLAs were only processed by coacervation. Satisfactory entrapment of 30-60% Dtxd was obtained. Here, albumin was a prerequisite for toxoid encapsulation, as BSA-free formulations produced strong toxoid precipitation. Furthermore, protein burst release increased with the more hydrophobic polymers, with Dtxd, Ttxd and the co-encapsulated BSA following a similar pattern and magnitude. This investigation also revealed that the method of protein extraction from the microspheres (O/W-partition or polymer hydrolysis) as well as the analytical methods (HPLC or ELISA) strongly influenced the determined amount of encapsulated toxoid and BSA. In conclusion, the study revealed the complexity of antigen microencapsulation when using different preparation and analytical techniques, as well as different types of materials.
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PMID:Diphtheria and tetanus toxoid microencapsulation into conventional and end-group alkylated PLA/PLGAs. 1038 3

Biodegradable polyester microspheres (MS) have shown potential for single-dose vaccines. This study examined the immunogenicity of diphtheria toxoid (Dtxd) microencapsulated in different types of poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA) MS prepared by the methods of spray-drying and coacervation. We investigated the influence of polymer type (PLGA 50:50 of low M(w); PLA of high M(w); end-group stearylated PLAs of low M(w)) and co-encapsulated excipients (BSA and/or trehalose) on Dtxd content, in vitro release and immunogenicity in guinea pigs. The co-encapsulated trehalose lowered the Dtxd entrapment efficiency in the spray-dried particles from 75 to 56%, whereas albumin alone had no effect in the spray-drying, but improved the encapsulation in the coacervation process. With the hydrophobic, end-group stearylated PLAs, Dtxd could only be encapsulated in the presence of albumin. Guinea pigs immunised with Dtxd-MS made with the relatively hydrophilic PLGA 50:50 exhibited specific and sustained antibody responses over 40 weeks, comparable to the responses to alum-adjuvanted toxoid. In contrast, undetectable or very low antibody responses were determined after immunisation with MS made with hydrophobic polymers. Surprisingly, large (15-60 microm) and small (1-5 microm) MS gave comparable primary antibody responses. In conclusion, the data presented confirm the feasibility of MS vaccines to induce strong, long-lasting protective antibody responses after a single immunisation.
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PMID:Immunogenicity of single-dose diphtheria vaccines based on PLA/PLGA microspheres in guinea pigs. 1050 44

Hemorrhagic shock due to major trauma predisposes to the development of acute respiratory distress syndrome. Because lung fibrin deposition is one of the hallmarks of this syndrome, we hypothesized that resuscitated shock might predispose to the development of a net procoagulant state in the lung. A rodent model of shock/resuscitation followed by low-dose intratracheal lipopolysaccharide (LPS), a clinically relevant "two-hit" model, was used to test this hypothesis. Resuscitated shock primed the lungs for an increased tissue factor and plasminogen activator (PA) inhibitor-1 gene expression in response to LPS, while the fibrinolytic PA was reduced. These alterations were recapitulated in isolated alveolar macrophages, suggesting their role in the process. LPS-induced tumor necrosis factor (TNF) was also augmented in animals after antecedent shock/resuscitation, and studies using anti-TNF antibodies revealed that TNF expression was critical to the induction of the procoagulant molecules and the reduction in PA. By contrast, TNF did not appear to play an important role in neutrophil sequestration in this model, inasmuch as anti-TNF had no effect on lung neutrophil accumulation or chemokine expression. However, treatment prevented albumin leak by preventing alveolar neutrophil activation. The inclusion of the antioxidant N-acetyl-cysteine in the resuscitation fluid resulted in prevention of both the development of the net procoagulant state and lung neutrophil sequestration, suggesting a role for upstream oxidant effects in the priming process. These studies provide a cellular and molecular basis for lung fibrin deposition after resuscitated shock and demonstrate a divergence of pathways responsible for fibrin generation and neutrophil accumulation.
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PMID:Priming for enhanced alveolar fibrin deposition after hemorrhagic shock: role of tumor necrosis factor. 1074 20


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