Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

For diseases in which thrombosis plays a pivotal role, such as virus-induced fulminant hepatitis, fetal loss syndrome, and xenograft rejection, the major procoagulant has remained elusive. Here we describe the isolation and functional expression of a distinct human prothrombinase, termed FGL2. The murine fgl2 gene product has been implicated in the pathophysiology of murine fulminant hepatitis. The predicted ORF corresponds to a 439-amino-acid type II integral membrane protein that contains a carboxy-terminal Fibrinogen-related domain. Functional analysis showed that FGL2-encoded protein is indeed a prothrombinase. This enzyme is a serine protease and directly cleaves prothrombin to thrombin. The FGL2 gene is a single-copy gene in the haploid human genome and has two exons separated by a 2195-bp intron expressing two mRNA transcripts of 1.5 and 5.0 kb. The 5'-flanking region contains putative cis-elements including a TATA box, an AP1 site, CEBP sites, Sp1 site, and Ets binding domains. By both radiation hybrid analyses and fluorescence in situ hybridization, human FGL2 was localized to 7q11.23.
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PMID:Genomic characterization, localization, and functional expression of FGL2, the human gene encoding fibroleukin: a novel human procoagulant. 1117 Jul 50

fgl2 prothrombinase, by its ability to generate thrombin, has been shown to be pivotal to the pathogenesis of viral-induced hepatitis, cytokine-induced fetal loss syndrome, and xeno- and allograft rejection. In this study, the molecular basis of fgl2 prothrombinase activity was examined in detail. Purified fgl2 protein generated in a baculovirus expression system had no measurable prothrombinase activity, whereas the activity was restored when the purified protein was reconstituted into phosphatidyl-L-serine-containing vesicles. Reconstituted fgl2 catalyzed the cleavage of human prothrombin to thrombin with kinetics consistent with a first order reaction, with an apparent V(max) value of 6 mol/min/mol fgl2 and an apparent K(m) value for prothrombin of 8.3 microM. The catalytic activity was totally dependent on calcium, and factor Va (500 nM) enhanced the catalytic efficiency of fgl2 by increasing the apparent V(max) value to 3670 mol/min/mol fgl2 and decreasing the apparent K(m) value for prothrombin to 7.2 microM. By a combination of site-directed mutagenesis and production of truncated proteins, it was clearly shown that residue Ser(89) was critical for the prothrombinase activity of fgl2. Furthermore, fgl2 prothrombinase activity was not inhibited by antithrombin III, soybean trypsin inhibitor, 4-aminobenzamidine, aprotinin, or phenylmethylsulfonyl fluoride, whereas diisopropylfluorophosphate completely abrogated the activity. In this work we provide direct evidence that fgl2 cleaves prothrombin to thrombin consistent with serine protease activity and requires calcium, phospholipids, and factor Va for its full activity.
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PMID:Kinetic analysis of a unique direct prothrombinase, fgl2, and identification of a serine residue critical for the prothrombinase activity. 1199 72

Fresh frozen plasma (FFP) contains higher levels of intact coagulation factors and coagulation and fibrinolysis inhibitors than solvent/detergent-treated plasma (SD plasma), and also greater residual cell contamination. SD plasma is a particle-free plasma of uniform quality. SD treatment, however, has the specific result of reducing the activities of some inhibitors. Both plasma types carry a minimal residual risk of transmitting human immunodeficiency virus (HIV)-1/2, hepatitis virus B (HBV), and hepatitis virus C (HCV), but SDP is, in addition, also safe with respect to other lipid-enveloped viruses and perhaps with respect to hepatitis virus A (HAV), also due to its antibody (Ab) content. Future revisions of therapeutic plasma safety and quality standards should consider the following points:For FFP:reduce residual cell count in all FFP units to values below 5 x 10(6) leukocytes/l;screen donors for Parvovirus B19 genome and antibodies in order to establish a sufficiently large collection of genome-negative and antibody-positive donors whose FFP can be used for selected patients;For SDP:introduce pool testing for Parvovirus B19 genome; fix an upper limit for genome and a lower limit for antibody content;in addition to the standard quality control methods for therapeutic plasma, focus on assays to test for functionally intact proteinase inhibitors such as alpha(2)antiplasmin (alpha(2)AP) and alpha(1)proteinase inhibitor (alpha(1)PI) that are important for plasma indications. Commercially available kits may not be sufficient to show changes in inhibition kinetics. For both types:introduce an activation marker such as thrombin-antithrombin complex (TAT) as a random test to monitor activation processes during withdrawal, separation, manufacturing, and storage;abolish inappropriate parameters like Antithrombin III (AT III) and coagulation factor XI that are not relevant for changes in plasma quality;finally, support every effort towards establishing an efficient documentation and reporting system on efficacy and side effects of plasma transfusions. Effective reporting alone might help to reveal deficiencies of specific plasma quality and to overcome them through modifications to manufacturing processes and testing, or by defining its indications more precisely.
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PMID:Quality of therapeutic plasma-requirements for marketing authorization. 1237 93

Blood collected by 11 Red Cross Regional Blood Centers were screened by the method of agar gel diffusion (AGD) for the presence of hepatitis-B antibody. Of the 185,134 units tested, 114 were found to be positive for HBAb by the Regional Centers and were forwarded to National Special Projects Laboratory for confirmation. Only five out of 114 samples revealed lines of identity with a control anti-HBAg when reacted with a pool of plasma positive for hepatitis-B antigen that was different from that which was provided to the Centers. Apparently, the precipitation reactions observed by the Centers were largely due to the antithrombin antibodies in the donors' sera reacting with the residual thrombin used by the manufacturer to convert HBAg positive plasma to serum. We conclude that the incidence of hepatitis-B antibody as measured by agar gel diffusion in the Red Cross Blood donor population was extremely low.
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PMID:American National Red Cross experience with hepatitis-B antibody (HBAb or anti-HBAg) testing. 1273 88

Fibrin sealants are prepared from fibrinogen, thrombin and sometimes also factor XIII that have been purified from human plasma. Bovine aprotinin is also included in some preparations. Each of these components has the potential to carry blood-borne pathogens, albeit at a very low frequency. In order to minimize the risk of viral transmission from commercial fibrin sealants, plasma donations undergo a series of procedures that contribute to avoiding, inactivating and eliminating potential contaminants. The procedures for selection and screening of plasma donors, and the testing of donated plasma, incorporates highly sensitive molecular techniques (e.g. PCR testing) and contributes significantly to reducing the theoretical possibility of viral transmission. The starting material for bovine aprotinin is also carefully selected, and the manufacturing process rigorously assessed, to minimize the putative risk of transmission of bovine spongiform encephalopathies. The manufacturing process for commercial fibrin sealants comprises a range of procedures, including heat treatment (e.g. pasteurization, dry or vapor heating), filtration, solvent/detergent treatment, precipitation, pH treatment and chromatography. Some steps are an inherent part of the purification process and others (e.g. pasteurization, nanofiltration) are deliberately introduced to inactivate/eliminate potential pathogens. Current manufacturing processes provide a very high degree of safety for fibrin sealants. In 20 years of worldwide use, there have been no known cases of hepatitis or HIV transmission associated with the use of commercial fibrin sealants.
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PMID:The safety of fibrin sealants. 1286 85

Both osteopontin (OPN) and natural killer T (NKT) cells play a role in the development of immunological disorders. We examined a functional link between OPN and NKT cells. Concanavalin A (Con A)-induced hepatitis is a well-characterized murine model of T cell-mediated liver diseases. Here, we show that NKT cells secrete OPN, which augments NKT cell activation and triggers neutrophil infiltration and activation. Thus, OPN- and NKT cell-deficient mice were refractory to Con A-induced hepatitis. In addition, a neutralizing antibody specific for a cryptic epitope of OPN, exposed by thrombin cleavage, ameliorated hepatitis. These findings identify NKT cell-derived OPN as a novel target for the treatment of inflammatory liver diseases.
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PMID:Osteopontin as a mediator of NKT cell function in T cell-mediated liver diseases. 1548 31

Procarboxypeptidase R (proCPR), also known as thrombin-activatable fibrinolysis inhibitor (TAFI), is present in plasma and can be activated to carboxypeptidase R (CPR) by trypsin-like enzymes such as thrombin and plasmin. CPR has the carboxypeptidase B-like activity that can inactivate the inflammatory peptides such as C5a by removing the C-terminal arginine and can interfere with fibrinolysis by removing C-terminal lysine residue of fibrin. In the present study, we conducted to produce monoclonal antibodies (mAbs) by using spleen cells from proCPR-deficient mice immunized by partially purified mouse proCPR. The mAbs obtained were IgM isotype and reacted with proCPR and interfered with activation of proCPR to CPR by thrombin-thrombomodulin complex. Some BALB/c mice implanted with the hybridoma died in 7 days, and intravenous injection of the mAb to BALB/c mice induced transient elevation of GOT and GPT in plasma although injection to the deficient mice did not. Furthermore, the histological features showed the focally lesions in liver tissue of BALB/c mice injected with the mAb. Since liver is the major site of proCPR synthesis, IgM mAb to proCPR should have induced local inflammation at the side resulting in induction of hepatitis.
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PMID:Hepatitis induced by an IgM monoclonal antibody against procarboxypeptidase R. 1584 Sep 63

Control of blood loss during urologic surgery is paramount to the success of patient recovery. Hemostatic agents and tissue sealants are used routinely to prevent excess blood loss and in reconstruction during surgical repair. Some of the available products include thrombin sealant, fibrin glue, bovine serum/albumin/glutaraldehyde, and gelatin matrix. Each of these agents differs in mechanism, cost, and application. Complications can include allergic reactions or thromboembolism and the risk of contracting bovine spongiform encephalitis or hepatitis. Many new hemostatic agents are being developed and approved. The benefits and risks of use of these agents versus conventional treatment need to be considered on a case-by-case basis by the surgeon.
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PMID:New generation tissue sealants and hemostatic agents: innovative urologic applications. 1704 7

Separation of concentrated bile acids from hepatic parenchymal cells is a key function of the bile duct epithelial cells (BDECs) that form intrahepatic bile ducts. Using coimmunostaining, we found that tissue factor (TF), the principal activator of coagulation, colocalized with cytokeratin 19, a marker of BDECs in the adult mouse liver. BDEC injury induced by xenobiotics such as alpha-naphthylisothiocyanate (ANIT) causes cholestasis, inflammation, and hepatocellular injury. We tested the hypothesis that acute ANIT-induced cholestatic hepatitis is associated with TF-dependent activation of coagulation and determined the role of TF in ANIT hepatotoxicity. Treatment of mice with ANIT (60 mg/kg) caused multifocal hepatic necrosis and significantly increased serum biomarkers of cholestasis and hepatic parenchymal cell injury. ANIT treatment also significantly increased liver TF expression and activity. ANIT-induced activation of the coagulation cascade was shown by increased plasma thrombin-antithrombin levels and significant deposition of fibrin within the necrotic foci. ANIT-induced coagulation and liver injury were reduced in low-TF mice, which express 1% of normal TF levels. The results indicate that ANIT-induced liver injury is accompanied by TF-dependent activation of the coagulation cascade and that TF contributes to the progression of injury during acute cholestatic hepatitis.
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PMID:Tissue factor-dependent coagulation contributes to alpha-naphthylisothiocyanate-induced cholestatic liver injury in mice. 1917 21

Although their central role is in the prevention of bleeding, platelets probably contribute to diverse processes that extend beyond hemostasis and thrombosis. For example, platelets can recruit leukocytes and progenitor cells to sites of vascular injury and inflammation; they release proinflammatory and anti-inflammatory and angiogenic factors and microparticles into the circulation; and they spur thrombin generation. Data from animal models suggest that these functions may contribute to atherosclerosis, sepsis, hepatitis, vascular restenosis, acute lung injury, and transplant rejection. This article represents an integrated summary of presentations given at the Fourth Annual Platelet Colloquium in January 2009. The process of and factors mediating platelet-platelet and platelet-leukocyte interactions in inflammatory and immune responses are discussed, with the roles of P-selectin, chemokines and Src family kinases being highlighted. Also discussed are specific disorders characterized by local or systemic platelet activation, including coronary artery restenosis after percutaneous intervention, alloantibody-mediated transplant rejection, wound healing, and heparin-induced thrombocytopenia.
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PMID:Platelet functions beyond hemostasis. 1969 83


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