| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Regular Articles |

From the Multi Organ Transplant Program, Toronto General Hospital
and The University of Toronto,*
Toronto, Ontario, Canada;
and Texas A & M University,
College
Station, Texas
| Abstract |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|
A novel murine cDNA fgl2, encoding a protein with prothrombinase-like activity, was previously cloned in our laboratory.2 The sequence of the cDNA was essentially identical to a previously described sequence corresponding to a gene encoding a mouse fibrinogen-like protein, originally described as a cytotoxic T-cell-specific gene. When the cDNA containing the entire coding region was expressed in RAW 264.7 cells, a prothrombinase activity was detected by both a one-stage clotting assay and cleavage of 125I-labeled prothrombin. Using a model of fulminant viral hepatitis, we demonstrated a causal relationship between the induction of fgl2 prothrombinase and the mortality of murine hepatitis virus infection (MHV-3).3 We demonstrated that after MHV-3 infection in susceptible mice, mRNA transcripts of fgl2 were seen in macrophages and endothelial cells in the liver followed by fibrin deposition and liver necrosis.4 The infusion of high-titered monoclonal antibodies to fgl2 prevented the coagulation disturbance, the hepatic necrosis, and mortality associated with MHV-3 infection.5
Here we report the isolation and characterization of the HFGL2 gene, which encodes for a potent prothrombinase and demonstrate mRNA transcripts of this gene in the earliest hepatic lesions of fulminant viral hepatitis. This study defines distinctive aspects of the cellular and molecular pathology of fulminant viral hepatitis and implicates viral-induced up-regulation of the potent human fgl2 prothrombinase gene in this lethal disease. Therapies directed toward this prothrombinase offer the potential for attenuation of disease in man, similar to exciting recent findings in a murine model of fulminant viral hepatitis.
| Materials and Methods |
|---|
|
|
|---|
Primers Used in Pi Artificial Choromosome (PAC) Library Screening
Primers specific to a recently reported cDNA sequence6 which correspond to exon 2 of mouse fgl2 were used to amplify the genomic DNA from human liver; the sense primer CAA AAG AAG CAG TGA TAC CTA CA (huflp7) at position 693 and the antisense primer TTA TCT GGA GTG AAA AAC TT (huflp8) at position 1115 of the reported human cDNA generated a probe of 423 nucleotides which was used to screen the human PAC library (Genome Systems, St. Louis, MO) and 3 clones were isolated. Restriction mapping of three PAC clones was performed with the frequently cutting enzymes EcoRI, HindIII, PstI, and PvuII and the rare cutting enzymes NotI, SalI, and SmaI. A plasmid sublibrary was prepared using partial Sau3A digestion and subcloned into the BamHI site of PBluescript 1 (Sk-; Stratagene, La Jolla, CA) as previously described.7
Construction of HFGL2 Expression Vector and Transient Expression of HFGL2 in CHO Cells
The HFGL2 cDNA coding region was amplified by polymerase chain reaction (PCR) from human small intestine total RNA using the forward primer TGA GCA GCA CTG TAA AGA TG 17 bp upstream of the translation start codon ATG and the reverse primer GTG GCT TAA AGT GCT TGG GT starting 6 bp upstream of the stop codon TAA to 11 bp downstream of TAA. The PCR product was first cloned into PCR II cloning vector (Invitrogen), sequenced, and subcloned into pcDNA 3.1 his mammalian expression vector inframe with the his-tag. Transfection of HFGL2 into CHO cells was performed using the lipofectamine reagent (Gibco, Mississauga, Ontario).
Northern Blot Analysis
The method of extraction of total RNA from tissue has been described elsewhere.8 In brief, 100 mg of tissue was homogenized in a denaturing solution containing 4 mol/L guanidine isothiocyanate, 25 mmol/L sodium citrate, 0.1 mol/L 2-mercaptoethanol, and 0.5% N-lauroylsarcosine. The homogenate was then mixed with 2 mol/L sodium acetate (pH 4.0), water-saturated phenol, and choloroform-isoamyl alcohol (49:1) and incubated on ice for 15 minutes. The mixture was centrifuged at 15,800 x g at 4°C for 20 minutes. The upper aqueous phase was transferred to a fresh tube and then mixed with an equal volume of 100% isopropanol and precipitated at -20°C for 20 minutes. RNA was pelleted by centrifugation at 15,800 x g at 4°C for 30 minutes and then dissolved in the denaturing solution, to which an equal volume of 100% isopropanol was added for reprecipitation of RNA at -20°C. After centrifugation, the RNA pellet was washed with 75% ethanol twice, dried in vacuum, and resuspended in DEPC-treated water.
Total cellular RNA (20 µg) from each tissue was first quantitated
spectroscopically and then electrophoresed in a 1% denaturing agarose
gel with 1.7% formaldehyde and then transferred to nitrocellulose
membranes (Schleicher & Schuell, Keene, NH) in 20 x SSC (1
x SSC in 0.15 mol/L NaCl plus 0.015 mol/L sodium citrate). RNA was
immobilized by baking the membrane at 80°C for 2 hours in vacuum and
was hybridized in 50% formamide-5 x SSPE (1 x SSPE
is 0.18 mol/L NaC1, 10 mm
NaH2PO4, and 1 mm
ethylenediaminetetraacetic acid [pH 7.1])-5 x Denhardts
solution-0.5% sodium dodecyl sulfate-100 µg of denatured salmon
sperm DNA per ml at 42°C for 18 hours with an
[
-32P]dCTP-labeled 539-bp DNA probe of human
fgl2 cDNA (7 x 108
cpm/µg) encompassing
nucleotides 100 (GCAAACAAT... ) to 639 (... ATACAGTCA). Labeled
human glyceraldehyde-3-phosphate dehydrogenase cDNA was used to ensure
the integrity of the RNA in each tissue. The membrane was washed with
1 x SSPE and 0.1% sodium dodecyl sulfate at room temperature for
15 minutes and then autoradiographed by exposure to Kodak film (X-OMAT;
Eastman Kodak Company, Rochester, NY).
Western Blot Methodology
Forty-eight hours after transfection, CHO cells were washed twice with phosphate-buffered saline before addition of 200 µl of lysis buffer (10 mmol/L Tris-HCI, pH 7.5, 150 nmol/L NaC1, 1 mmol/L ethylenediaminetetraacetic acid, 0.25% NP-40, 0.2 mg of phenylmethylsulfonyl fluoride per ml) at 106 cells/100 µl for 20 minutes at 4°C. Lysates were clarified by centrifugation, and 20 µl of each was separated by 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to a Hybond-N nitrocellulose membrane (Amersham, Mississauga, Ontario). Membranes were probed with monoclonal anti-His antibody (Invitrogen). Bound antibodies were visualized with an enhanced chemiluminescence detection system (Amersham).
Clotting Assay
Transfected CHO cells were harvested after 48 hours of transfection and suspended in unsupplemented RPMI 1640 at a concentration of 2 x 106 cells/ml. The cells were then subjected to three cycles of freeze-thawing to obtain maximal total cellular procoagulant activity. Samples were assayed for the ability to shorten the spontaneous clotting time of normal citrated human platelet-poor plasma.7 Milliunits of procoagulant activity were assigned by reference to a standard curve generated with serial log dilutions of a standard rabbit brain thromboplastin (Sigma Chemical Co., St. Louis, MO) as previously described.9 Media and reagents were without activity.
Prothrombin Cleavage Assay
Factor X and prothrombin were isolated from Cohn fraction III.10 For assay of cleavage, prothrombin was radioiodinated enzymatically with immobilized lactoperoxidase and glucose oxidase (Enzymobeads; Biorad, Richmond, CA) to a specific activity of 6.2 µCi/µg. To 25 µl of cellular homogenate, 10 µl of 125I-prothrombin and 10 µl of 25 mmol/L CaC12 were added. The reaction was allowed to proceed at 37°C for 30 minutes. Human factor Xa (0.5 µg/ml), generated by incubating 0.6 ng human factor X with 0.06 ng of Russells viper venom as previously described, in the presence of homogenates of CHO cells was used as a positive control for 125I-prothrombin cleavage. Each reaction mixture was electrophoresed on 10% polyacrylamide gel. After electrophoresis, the gels were fixed, dried, and subjected to autoradiography.
Methods for Cellular and Molecular Histopathological Analysis
Eight cases of fulminant viral hepatitis were examined (virus types: hepatitis B, 3; syncytial giant cell hepatitis with paramyxoviral like particles, 1; hepatitis virus non-A non-B non-C, 4). The micrographs shown are from one of the latter cases which are representative of all cases presented. Histological sections were stained with hematoxylin and eosin.
Immunoperoxidase staining (dark brown) used the avidin-biotin complex method. For fibrin detection, a rabbit-anti-human fibrinogen antibody (DAKO, Carpenteria, CA), known to react with fibrinogen and fibrin in human tissues was used. The CD68 antibody (DAKO) was used to detect macrophages (histiocytes). A 216-bp DNA fragment from the conserved carboxyl end of the hfgl2 coding region was used as a template, to synthesize, with T3 and T7 RNA polymerases, digoxigenin-11-UTP (Boehringer Mannheim, Laval, PQ)-labeled sense and antisense cRNA probes for the in situ hybridization studies.4 Alkaline phosphatase (dark blue) served as a marker of the reaction product. Tissue for electron microscopy was prepared by routine methods,11 ultra-thin epon embedded sections were stained with lead citrate and examined in a Philips 400 electron microscope (Einthoven, The Netherlands).
| Results |
|---|
|
|
|---|
The HFGL2 gene was isolated using three genomic
clones from a human PAC library (Genome Systems Inc., St Louis, MO)
using a PCR-based approach (Figure 1)
.
The HFGL2 gene was localized to the short arm of
chromosome 7 by fluorescence in situ hybridization and
radiation hybrid mapping (data not shown). The HFGL2
gene is approximately 7 kb in length. This size was determined by the
known mRNA sequence that contains exon I and II (4.4 kb) plus an intron
sequence of 2.2 kb. Exon II encodes for the last 235 amino acids of the
HFGL2 protein and contains the 3' UTR. The putative
promoter region contains cis element consensus sequences
such as a TATA box, an AP1 site, a C/EBP binding site (CAAT), and
multiple Ets sites which suggest the inducibility of
HFGL2. Of interest, the C/EBP binding sites have been
shown to play a pivotal role in the induction of acute phase response
genes of the liver and cytokine genes of macrophages.12,13
|
|
|
|
|
The eight instances of fulminant viral hepatitis examined all had
classical pathological features. The patients ranged in age from 0.5 to
53 years; 6 were females and 2 were males (Table 2)
. The livers were removed at
transplantation for fulminant hepatic failure and showed widespread
(range, 60% to 90%) hepatocellular necrosis (Table 3)
. In six instances, there were
surviving areas of parenchyma comprising less than 40% of the liver.
These areas typically showed earlier stages of active hepatitis with
focal, confluent, or bridging necrosis (Figure 5)
. In two instances, the entire liver
showed end-stage liver disease with total panlobular necrosis. All were
examined by in situ hybridization for the presence of
HFGL2 prothrombinase mRNA transcripts and by
immunohistochemical methods for CD68-positive macrophages or
histiocytes as well as fibrin. In the four cases in which surviving
parenchyma was seen, fgl2 prothrombinase RNA was detected in
macrophages in association with fibrin deposits in vascular sinusoids
located selectively in the areas of acute focal, confluent, or bridging
necrosis but was infrequent or absent in the more advanced areas of
panlobular necrosis in which only the consequences of the active
hepatocellular necrotizing process remained. Fibrin deposits were
observed by immunoperoxidase staining with an antibody specific for
fibrinogen and fibrin, and fibrin thrombi in sinusoids were confirmed
by electron microscopy. Panels A to E in Figure 5
are all from areas of
residual parenchyma to show regions of bridging necrosis and for
comparison, a large area of complete hepatic necrosis and collapse.
Panels D and E are deeper sections of the same block that are matched
to show equivalent areas of acute bridging necrosis. The positive cells
(dark blue stained cells) in the in situ micrograph (E)
correspond to the large macrophages (CD68-positive cells) in micrograph
(D). Panel C (electron micrograph) is also from an area of acute
bridging necrosis.
|
|
|
| Discussion |
|---|
|
|
|---|
Of particular relevance to this study, are recent studies of murine viral hepatitis caused by mouse Coronavirus (murine hepatitis virus type 3, MHV-3) in susceptible strains which is an excellent animal model for studying the pathogenesis of fulminant viral hepatitis.3 Especially important is that MHV-3 infection in susceptible BALB/cJ mice causes the de novo synthesis of a unique procoagulant fgl2 prothrombinase by macrophages.2 The murine fgl2 gene has been cloned, sequenced, and characterized in this laboratory.2,4,14,15 Recent sequential studies showed that the development of fulminant viral hepatitis always followed the same pattern: initiation by viral-induced up-regulation of the fgl2 prothrombinase gene with focal deposits of fibrin in sinusoids and accumulation of inflammatory cells with a predominance of neutrophils and macrophages and focal individual liver cell necrosis. Progression ensued by further fibrin deposition and arrest of sinusoidal blood flow leading to the rapid development of confluent multicellular hepatic necrosis resulting in fulminant hepatic failure and death in 4 days.4 There is strong evidence for implicating fgl2 prothrombinase as pivotal in the pathogenesis of this disease in the mouse model: levels of this prothrombinase activity correlate with the severity of the disease;16,17 and there is concordance between expression of fgl2 prothrombinase in the liver with fibrin deposition; and neutralizing antibodies attenuate the pathological and clinical manifestations.5 Indeed, it is not the viral load that determines the occurrence of massive necrosis but the viral induced up-regulation of the fgl2 gene which initiates the pathological process.5,18 Although, treatment with neutralizing antibodies to the fgl2 gene abrogates the disease, a high viral load persists.5 Fulminant murine hepatitis and fgl2 gene expression were shown to be genetically linked and it is likely that host genetic factors are also important in human fulminant hepatitis.19
The similarities in the putative promoter elements in human and mouse fgl2 indicate they are both regulated in a similar manner. Recently we have shown that the nucleocapsid protein of strains of MHV which cause fulminant hepatic failure is responsible for transcription of the fgl2 gene.20 By mapping of the fgl2 promoter, we have defined an enhanceosome consisting of three transcription elements LF-A1, GMCSF, and IE1.2. Interestingly, LF-A1 is a liver specific promoter element that regulates transcription of known coagulation factors.21-23 The fact that the severity of both hepatitis B and hepatitis C are related to expression of the nucleocapsid protein (core protein) suggests that these studies of MHV may parallel the pathogenesis of human viral hepatitis.20
Other investigators have implicated thrombin as a pivotal mediator in liver injury, and in particular in acute viral fulminant hepatitis.24-27 The local production of thrombin may explain the fibrin deposition during acute liver injury. In favor of this, is the recent report demonstrating increased expression of the thrombin receptor in patients with fulminant hepatitis.28
Other inflammatory mediators including tumor necrosis factor-
(TNF-
), interleukin-1 (IL-1), and reactive oxygen intermediates have
also been implicated in the pathogenesis of organ
failure.29,30
Treatment of rats with recombinant
neutralizing antibody to TNF-
has been shown to protect against
hypotension, hypothermia, and mortality of Gram-negative
sepsis.31,32
Furthermore, the mortality associated with
endotoxin shock was reduced with an IL-1 receptor
antagonist.33
We have previously reported that IL-1 and
TNF-
induce endothelial cell transcription of fgl2 linking cytokines
and induction of coagulation.18
However, antibodies to TNF
or IL-1 were unable to prevent the hepatic necrosis caused by
MHV-3.3
The role of the immune coagulation system in
fulminant hepatic failure is controversial.33
Mori et
al34
have reported that fibrin is a classical feature but
this has not been substantiated by others. The reason for not finding
fibrin may be attributed to its transient nature as reported here, and
also the lack of precision of the histological methodologies used to
detect fibrin in tissues. It is also pertinent to mention here that
other investigators have cloned and sequenced HFGL2 and
termed it musfblp in the mouse35
and fibroleukin in
humans.36
Both groups isolated the molecule from T
lymphocytes and postulated its role as an extracellular matrix protein
important in regulatory T-cell activation. It is also important to note
that other molecules with homology to fgl2 such as
cytotaxin37
or tenascin,38
have potent
immunoregulatory effects on T cells. Thus, expression of
HFGL2 may explain accumulation of inflammatory cells in
areas of liver injury and immunological disturbances that may
contribute to the hepatic necrosis. Preliminary results from our
laboratory have shown that recombinant fgl2 is a potent inhibitor of
mixed lymphocyte reaction and cytotoxic T cell responses (work
in progress). These findings may explain the immunosuppressant status
and inability to clear the virus in patients and mice with fulminant
hepatic failure.
The amino acid sequence suggests that both HFGL2 and fgl2 are either secreted or type II transmembrane proteins. Ruegg and Pytela6 have suggested that HFGL2 is a secreted protein. However, further analysis of the sequence suggests that the protein is a type II transmembrane protein. This is based on the fact that the region from position 3 to 23 is hydrophobic. This 21-amino acid log stretch is sufficiently long enough to span the layered phospholipid cell membrane. Furthermore, the amino terminus has a tendency to maintain a helical configuration characteristic of transmembrane domains.39 Previously, we reported that fgl2 was a serine protease based on inhibition studies with diisopropyl fluorophosphate and other serine protease inhibitors.40 Unlike the serine proteases of the coagulation cascade with the catalytic domain GDSGG, belonging to clan SA, HFGL2 could belong to clan SE serine protease with the active site motif S..K. The motifs at positions 91 and 142 could potentially serve as the catalytic sites. Preliminary data using site-directed mutagenesis suggest that the motif at position 91 is the active catalytic domain (unpublished data). After the cystein at position 213, the rest of the carboxyl end of the HFGL2 protein consists of a domain homologous to the FREDs (fibrinogen related domain) which is found on a number of different proteins with functional diversity. Examples of these proteins are the three chains of fibrinogen, tenacin, ficolin, and HFREP-1.41-43
The molecular and cellular results reported here in human fulminant hepatitis mimic closely the changes observed in the murine model in which the pathogenesis of the disease has been studied in a stepwise fashion.3,4 A common molecular mechanism is suggested. The viral induced up-regulation of the fgl2 gene and the potent prothrombinase molecule it encodes plays a pivotal role in initiating the immunothrombotic microcirculatory changes that lead to the rapidly spreading necrosis. Thus, there is a causal link between fgl2 gene up-regulation that initiates immune coagulation and the transient but devastating microthrombosis in sinusoids resulting in rapid, progressive, and widespread hepatocellular necrosis both in humans and in mice. Having established this relationship, the provocative and exciting findings of successful abrogation of the lethal effects of the fgl2 gene in murine fulminant viral hepatitis offers the potential for developing methods for attenuating the disease in man.
| Footnotes |
|---|
Supported by group grant GR13298 from the Medical Research Council of Canada.
Accepted for publication December 9, 1999.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
M. Han, W. Yan, Y. Huang, H. Yao, Z. Wang, D. Xi, W. Li, Y. Zhou, J. Hou, X. Luo, et al. The Nucleocapsid Protein of SARS-CoV Induces Transcription of hfgl2 Prothrombinase Gene Dependent on C/EBP Alpha J. Biochem., July 1, 2008; 144(1): 51 - 62. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. Shalev, H. Liu, C. Koscik, A. Bartczak, M. Javadi, K. M. Wong, A. Maknojia, W. He, M. F. Liu, J. Diao, et al. Targeted Deletion of fgl2 Leads to Impaired Regulatory T Cell Activity and Development of Autoimmune Glomerulonephritis J. Immunol., January 1, 2008; 180(1): 249 - 260. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Phillippe, D. F. Bradley, K. Phillippe, and D. Engle Tissue Prothrombinase Activity in Myometrium From Timed-Pregnant Rats Reproductive Sciences, October 1, 2006; 13(7): 477 - 482. [Abstract] [PDF] |
||||
![]() |
M. Liu, M. Mendicino, Q. Ning, A. Ghanekar, W. He, I. McGilvray, I. Shalev, D. Pivato, D. A. Clark, M. J. Phillips, et al. Cytokine-Induced Hepatic Apoptosis Is Dependent on FGL2/Fibroleukin: The Role of Sp1/Sp3 and STAT1/PU.1 Composite cis Elements. J. Immunol., June 1, 2006; 176(11): 7028 - 7038. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Mendicino, M. Liu, A. Ghanekar, W. He, C. Koscik, I. Shalev, M. Javadi, J. Turnbull, W. Chen, L. Fung, et al. Targeted Deletion of Fgl-2/Fibroleukin in the Donor Modulates Immunologic Response and Acute Vascular Rejection in Cardiac Xenografts Circulation, July 12, 2005; 112(2): 248 - 256. [Abstract] [Full Text] [PDF] |
||||
![]() |
Q. Ning, Y. Sun, M. Han, L. Zhang, C. Zhu, W. Zhang, H. Guo, J. Li, W. Yan, F. Gong, et al. Role of Fibrinogen-Like Protein 2 Prothrombinase/Fibroleukin in Experimental and Human Allograft Rejection J. Immunol., June 1, 2005; 174(11): 7403 - 7411. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. E. Olson, V. P. Winfrey, S. K. NagDas, and M. H. Melner Region-specific Expression and Secretion of the Fibrinogen-related Protein, fgl2, by Epithelial Cells of the Hamster Epididymis and Its Role in Disposal of Defective Spermatozoa J. Biol. Chem., December 3, 2004; 279(49): 51266 - 51274. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Ghanekar, M. Mendicino, H. Liu, W. He, M. Liu, R. Zhong, M. J. Phillips, G. A. Levy, and D. R. Grant Endothelial Induction of fgl2 Contributes to Thrombosis during Acute Vascular Xenograft Rejection J. Immunol., May 1, 2004; 172(9): 5693 - 5701. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. W. Hancock, F. M. Szaba, K. N. Berggren, M. A. Parent, I. K. Mullarky, J. Pearl, A. M. Cooper, K. H. Ely, D. L. Woodland, I.-J. Kim, et al. Intact type 1 immunity and immune-associated coagulative responses in mice lacking IFN{gamma}-inducible fibrinogen-like protein 2 PNAS, March 2, 2004; 101(9): 3005 - 3010. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. A. Clark, K. Foerster, L. Fung, W. He, L. Lee, M. Mendicino, U. R. Markert, R. M. Gorczynski, P. A. Marsden, and G. A. Levy The fgl2 prothrombinase/fibroleukin gene is required for lipopolysaccharide-triggered abortions and for normal mouse reproduction Mol. Hum. Reprod., February 1, 2004; 10(2): 99 - 108. [Abstract] [Full Text] [PDF] |
||||
![]() |
Q. Ning, S. Lakatoo, M. Liu, W. Yang, Z. Wang, M. J. Phillips, and G. A. Levy Induction of Prothrombinase fgl2 by the Nucleocapsid Protein of Virulent Mouse Hepatitis Virus Is Dependent on Host Hepatic Nuclear Factor-4alpha J. Biol. Chem., April 25, 2003; 278(18): 15541 - 15549. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. W. Y. Chan, L. S. Kay, R. G. Khadaroo, M. W. C. Chan, S. Lakatoo, K. J. Young, L. Zhang, R. M. Gorczynski, M. Cattral, O. Rotstein, et al. Soluble Fibrinogen-Like Protein 2/Fibroleukin Exhibits Immunosuppressive Properties: Suppressing T Cell Proliferation and Inhibiting Maturation of Bone Marrow-Derived Dendritic Cells J. Immunol., April 15, 2003; 170(8): 4036 - 4044. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. F. Rychlik, E. K. Chien, D. Wolff, S. Phillippe, and M. Phillippe Cloning and Tissue expression of the Tissue Prothrombinase Fgl-2 in the Sprague-Dawley Rat Reproductive Sciences, February 1, 2003; 10(2): 67 - 73. [Abstract] [PDF] |
||||
![]() |
M. Phillippe, D. Wolff, T. Saunders, L. Thomas, and J. Chapa Intrauterine Expression of Prothrombin in the Sprague-Dawley Rat Reproductive Sciences, September 1, 2002; 9(5): 276 - 281. [Abstract] [PDF] |
||||
![]() |
C. W. Y. Chan, M. W. C. Chan, M. Liu, L. Fung, E. H. Cole, J. L. Leibowitz, P. A. Marsden, D. A. Clark, and G. A. Levy Kinetic Analysis of a Unique Direct Prothrombinase, fgl2, and Identification of a Serine Residue Critical for the Prothrombinase Activity J. Immunol., May 15, 2002; 168(10): 5170 - 5177. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |