Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have generated for the first time monoclonal antibodies (mAbs) specific for topoisomerase I (topo I) from scleroderma patients, and tight skin mice which develop a scleroderma-like syndrome. The epitope specificity of these antibodies has been determined using a series of fusion proteins containing contiguous portions of topo I polypeptide. Western blot analysis demonstrated that both human and mouse mAbs bound strongly to fusion protein C encompassing the NH2-terminal portion of the enzyme, and weakly to fusion proteins F and G containing regions close to the COOH-terminal end of the molecule. This crossreactivity is related to a tripeptide sequence homology in F, G, and C fusion proteins. It is interesting that a pentapeptide sequence homologous to that in fusion protein C was identified in the UL70 protein of cytomegalovirus, suggesting that activation of autoreactive B cell clones by molecular mimicry is possible. Both human and mouse mAbs exhibiting the same antigen specificity, also share an interspecies cross-reactive idiotope. These data suggest that B cell clones producing antitopo autoantibodies present in human and mouse repertoire are conserved during phylogeny, and are activated during the development of scleroderma disease.
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PMID:Antitopoisomerase I monoclonal autoantibodies from scleroderma patients and tight skin mouse interact with similar epitopes. 137 44

The authors have investigated the effects of double-membrane filtration with hollow fiber membranes made of different artificial materials and low-density lipoprotein (LDL)-adsorbent dextran sulfate cellulose (DS) columns on coagulation-related proteins and complement components to evaluate their hemocompatibility. All membrane filters showed similar sieving effects, which depended upon the molecular weights of the proteins. In the double-membrane filtration system, free protein S, protein C, antithrombin III, and alpha 1-antitrypsin were returned to the intracorporeal circulation, whereas alpha 2-macroglobulin and fibrinogen were almost completely removed from the circulation; C4b-binding protein (C4BP)-protein S complexes were also trapped by the second membrane, and in some instances were even blocked by the first membrane, if it was made of material that activated the classic pathway of the complement system. The DS column adsorbed C4BP-protein S complex, but free protein S was almost completely recovered in the eluate.
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PMID:The effect of low-density lipoprotein apheresis on plasma thrombomodulating factors. 138 16

Multiple elements in the upstream region of the GAPDH gene play a role in mediating the acute and chronic effect of insulin on GAPDH gene expression. The complexity of this regulation provides many layers of control. In differentiated tissues, the transcriptional response to insulin results from the additive effects of g/TRE, IRE-A and IRE-B. The gTRE may interact with newly synthesized c-fos/c-jun heterodimer to activate GAPDH gene transcription. Studies are underway to determine whether protein synthesis inhibitors affect the regulation of GAPDH. Because there are several elements that mediate the effect, it will be difficult to determine the significance of these findings until each cis-acting factor and its binding protein can be studied in isolation. IRE-A and IRE-B act together to promote a 5- to 8-fold insulin effect on HGAPDH-CAT in H35 hepatoma cells and a 3-fold effect in 3T3 adipocytes. We have succeeded in detecting an insulin-sensitive DNA-binding protein referred to as IREA-BP with an element -480 to -435. Insulin treatment of differentiated 3T3 adipocytes for 1 hr results in a 4-fold increase in the amount of this binding protein, as estimated by the amount of 32P-labelled oligonucleotide retarded on non-denaturing PAGE (11). The effect of insulin on IRP-B is comparable. Furthermore, IREA-BP is induced during the process of fasting and refeeding rats, an important in vivo correlate with our tissue culture models (11). These observations imply that the binding proteins IREA-BP and IRP-B are essential components in the signal transduction pathway of insulin action on GAPDH gene expression in metabolically active tissues such as fat and liver. Differentiation-dependence and tissue-specificity are achieved through multiple regulatory elements and involve pre- and post-translational regulation of multiple transcription factors. IREA-BP is present in preadipocytes but activity in highly induced upon differentiation of preadipocytes to adipocytes. The IRE-B (-408 to -269) DNA binding protein is not detected in 3T3 preadipocytes. A gC/EBP like-protein takes part in the formation of this complex which may explain the inductive effect of differentiation on binding. Finally, footprint and cotransfection studies indicate that the differentiation-dependent protein C/EBP also regulates GAPDH gene transcription through a motif located within one hundred nucleotides of the promoter. We have begun to clone the IRE-A and IRE-B DNA binding proteins. An IRE-A binding protein that footprints the 3' domain of the IRE-A has been cloned.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Multiple insulin-responsive elements regulate transcription of the GAPDH gene. 138 8

We have studied the behaviour of total protein S, free protein S, protein C and C4b-binding protein fifteen neonates with severe infections, eight with septic shock and in a group of ten healthy newborns. Protein C was decreased in shock and septic patients, but only the shock group showed significant differences compared to normal neonates. Total protein S was normal in both groups of patients, although free protein S had significantly lower values in shock and nonshock infants. C4b-binding protein was higher than normal in septic and shock patients compared to the control group. Decreased values of protein C and free protein S can be explained by the activation of coagulation and their subsequent consumption. On the other hand, the increased levels of C4b-binding protein can affect the distribution of protein S in plasma, producing a shift in protein S to the complexed inactive form. These findings can contribute to an increased risk of microthrombosis during neonatal sepsis.
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PMID:Protein C, protein S and C4b-binding protein in neonatal severe infection and septic shock. 138 81

The plasma concentrations of antithrombin III, protein C and protein S in capillary and venous blood samples obtained simultaneously from 30 neonates were compared in order to determine the suitability of using capillary blood for estimation of these proteins with anticoagulant action. Our findings showed that while capillary and venous blood did not differ significantly in antithrombin III functional activity and protein C antigen levels, the capillary samples had significantly lower protein C functional activity and higher antithrombin III antigen level. Protein S antigen level was also significantly higher in the capillary samples although the difference was relatively small. The capillary and venous concentrations of the binding protein of protein S, C4b binding protein, were almost identical.
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PMID:Comparison of antithrombin III, protein C and protein S levels in capillary and venous blood of newborn infants. 138 30

Coronary thrombolysis reduces morbidity and mortality in patients with acute myocardial infarction, however, the exact effects of thrombolytic agents on the status of intrinsic hemostases are not fully understood. In the present study, we examined serial changes in plasma thrombin and protein C activities of 6 patients with acute myocardial infarction treated with urokinase. Fibrinolysis occurred immediately after urokinase injection with an increase in the plasma thrombin-antithrombin III complex, suggesting a subsequent procoagulant state due to thrombin generation. Correspondent increases in plasma protein C activity were observed, however, protein S levels did not change at all. Our findings suggest that urokinase administration for coronary thrombolysis not only causes fibrinolysis, but also induces thrombin activity, which may be antagonized by augmented intrinsic protein C activity.
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PMID:Augmented plasma protein C activity after coronary thrombolysis with urokinase in patients with acute myocardial infarction. 138 46

Rate constants for human factor Va inactivation by activated human protein C (APC) were determined in the absence and presence of Ca2+ ions, protein S and varying concentrations of phospholipid vesicles of different lipid composition. APC-catalyzed factor Va inactivation in free solution (in the presence of 2 mM Ca2+) was studied under first-order reaction conditions with respect to both APC and factor Va and was characterized by an apparent second-order rate constant of 6.1 x 10(5) M-1 s-1. Stimulation of APC-catalyzed factor Va inactivation by phospholipids was dependent on the concentration and composition of the phospholipid vesicles. Optimal acceleration (230-fold) of factor Va inactivation was observed with 10 microM phospholipid vesicles composed of 20 mol% dioleoylglycerophosphoserine (Ole2GroPSer) and 80 mol% dioleoylglycerophosphocholine (Ole2GroPCho). At higher vesicle concentrations and at higher molar fractions of Ole2GroPSer some inhibition of APC-catalyzed factor Va inactivation was observed. Membranes that contained anionic phospholipids other than phosphatidylserine also promoted factor Va inactivation. The ability of different anionic lipids to enhance factor Va inactivation increased in the order phosphatidylethanolamine less than oleic acid less than phosphatidic acid less than phosphatidylglycerol less than phosphatidylmethanol less than phosphatidylserine. APC-catalyzed factor Va inactivation in the presence of phospholipid vesicles could be saturated with respect to factor Va and the reaction obeyed Michaelis-Menten kinetics. Both the Km for factor Va and the Vmax of factor Va inactivation were a function of the phospholipid concentration. The Km increased from 1 nM at 2.5 microM phospholipid (Ole2GroPSer/Ole2GroPCho 20:80, mol/mol) to 65 nM at 250 microM phospholipid. The Vmax increased from 20 mol factor Va inactivated.min-1.mol APC-1 at 2.5 microM phospholipid to 62 mol factor Va inactivated.min-1.mol APC-1 at 10 microM phospholipid and remained constant at higher phospholipid concentrations. Protein S appeared to be a rather poor stimulator of APC-catalyzed factor Va inactivation. Protein-S-dependent rate enhancements were only observed in reaction mixtures that contained negatively charged phospholipid vesicles. Independent of the concentration and the lipid composition of the vesicles, protein S caused a twofold stimulation of APC-catalyzed factor Va inactivation. This suggests that, in the human system, enhancement of APC binding to phospholipid vesicles by protein S is of minor importance. Considering that protein S is a physiologically essential antithrombotic agent, it is likely that other factors or phenomena contribute to the in vivo antithrombotic action of protein S.
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PMID:The effect of phospholipids, calcium ions and protein S on rate constants of human factor Va inactivation by activated human protein C. 138 59

This report describes the development of microplate-based blood coagulation assays. The assays require a kinetic microplate reader to follow changes in absorbance at 405 nm caused by the coagulating plasma. Procedures for performing prothrombin time and activated partial thromboplastin time tests are described with intra- and inter-assay variability of a few percentage points. The prothrombin time of normal plasma was 64.5 +/- 3.6 s, and the activated partial thromboplastin time was 69.8 +/- 3.2 s. Clotting times were prolonged when normal plasma was mixed with plasmas deficient in particular coagulation factors, as expected. These assays take advantage of the microplate format (small sample size and multiple simultaneous assays) and can be customized for specific purposes, such as quantifying purified factor IX or assessing protein C activity in plasma.
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PMID:Microplate coagulation assays. 138 75

Surfactant protein C (SP-C) is a lung-specific, hydrophobic peptide found in organic extracts of pulmonary surfactant. Alveolar SP-C (3.5 kD) is produced from proteolytic cleavage of a larger precursor molecule (pro-SP-C; 21 kD). While SP-C is synthesized by type II cells, the pathways for processing and secretion have remained elusive due, in part, to the lack of monospecific antibodies against SP-C or its precursors. This report describes production and characterization of a new antibody directed against pro-SP-C epitopes. Polyclonal antisera (anti-CPRO-SP-C) was prepared using a synthetic peptide corresponding to a portion of rat SP-C cDNA sequence (Ile26-Ser72). This contained amino acids 3-35 of mature SP-C plus additional C-terminal residues (His59-Ser72). On Western blots, anti-CPRO-SP-C competitively reacted to CPRO-SP-C but not to mature SP-C. Immunoblots of in vitro synthesized pro-SP-C confirmed that the antisera also recognized native protein. Immunocytochemistry with anti-CPRO-SP-C demonstrated staining for pro-SP-C peptides in isolated type II cells as well as in alveolar epithelial cells of rat lung sections. Pro-SP-C preferentially co-localized to cells that stained positive for Maclura pomifera antigen. Anti-CPRO-SP-C staining was not observed in lung interstitium, pulmonary vasculature, or several control tissues (brain, heart, and liver were negative). Western blotting of subcellular fractions demonstrated pro-SP-C peptides in plasma membrane (20 kD) and microsomal (20 and 21 kD) fractions with a 16 kD peptide present in lamellar bodies. No pro-SP-C peptides were detected in purified surfactant. These results demonstrate the use of a synthetic peptide to generate specific antiserum against more hydrophilic domains of pro-SP-C sequences and confirm that SP-C propeptides are unique to the lung.
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PMID:An antibody with specificity for surfactant protein C precursors: identification of pro-SP-C in rat lung. 138 9

The hemostatic system is assumed to be similar in children and adults and reference ranges established for adults are commonly used to evaluate children suspected of having congenital or acquired hemostatic problems. However, we know that the hemostatic system is not fully mature by 6 months of age and comprehensive studies of healthy older children have not been published. Therefore, we conducted a prospective cohort study of the hemostatic system in healthy children having minor, elective day surgery. After obtaining informed consent, a 3-mL blood sample was obtained at the time routine preoperative blood work was drawn. The plasma was fractioned and stored at -70 degrees C for batch assaying. We measured the concentration of 33 components of the hemostatic system (functional and immunologic assays) and the bleeding time (automated pediatric device) in 246 children aged 1 to 16 inclusive (a minimum of four subjects at each age). Eleven components of hemostasis (fibrinogen, prekallikrein, high-molecular weight kininogen, factors VIII and XIII, antithrombin III [ATIII], heparin cofactor II [HCII], alpha 1-antitrypsin [alpha 1AT], protein S, plasminogen, alpha 2-antiplasmin [alpha 2AP]) had mean values and ranges of normal that were similar to adults. Mean values of seven coagulants (II, V, VII, IX, X, XI, XII) were significantly lower than adult values and varied with age. Values for three inhibitors, alpha 2-macroglobulin (alpha 2M), protein C, and protein C1-inhibitor (C1-Inh) also differed from adults. Alpha 2M and C1-Inh inhibitor levels were elevated throughout childhood, whereas protein C levels were low, with a lower limit of normal of 0.40 U/mL until the age of 11. Finally, the upper limit of normal for the bleeding time was longer in children during the first 10 years of life, but decreased to adult values in the teenage years. In summary, there are important physiologic differences in the hemostatic system in children compared with adults. The decreased levels of several critical coagulants and increased levels of alpha 2M may contribute in part to the lower risk of thrombotic events in childhood. Age-matched controls should be used for evaluation of the hemostatic system in children with suspected congenital or acquired defects.
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PMID:Maturation of the hemostatic system during childhood. 139 57


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