Expression and Purification of Human Coagulation Factor X in Mammalian CHO-DG44 Cells

[Objectives]This study was conducted to obtain a Chinese hamster ovary cell line that stably expresses recombinant human coagulation factor X(rhFX),and to induce efficient expression of the target gene with different concentrations of methotrexate(MTX).[Methods]PCR was performed to obtain the rhFX gene,and a recombinant expression plasmid pOptiVEC-rhFX was constructed and subjected to double restriction endonuclease digestion and sequencing identification.CHO-DG44(DHFR-)cells were transfected by the liposome method,and the target protein was purified by affinity chromatography and detected by SDS-PAGE electrophoresis and Western blot.A cell line with efficient and stable expression of the target gene was obtained by increasing the concentration of MTX to select positive clones.[Results]PCR yielded a 1509 bp rhFX sequence,and the results of double digestion and sequencing showed that the constructed pOptiVEC-rhFX plasmid was correct.After transfection of cells,MTX significantly increased protein expression.When MTX reached 1.0μmol/L,the expression efficiency of the target protein was(9±0.27)μg/ml.The purity of the target protein purified by affinity chromatography was 93%,which could be used for subsequent experiments.The expression efficiency of rhFX in eukaryotic mammalian cells was improved by increasing MTX concentration,and an affinity chromatography purification process for the target protein was preliminarily established.[Conclusions]The results of this study provide data support for the expression and purification of rhFX,and will lay a solid foundation for the development of drugs related to rhFX.

Effects on coagulation factor production following primary hepatomitogen-induced direct hyperplasia

AIM： To investigate the molecular mechanisms involved in coagulation factor expression and/or function during direct hyperplasia （DH）-mediated liver regeneration. METHODS： Direct hyperplasia-mediated liver regeneration was induced in female C57BL/6 mice by administering 1,4-bisr2-（3,5-dichloropyridyloxy）] benzene （TCPOBOP）, a representative hepatomitogen. Mice were weighed and sacrificed at various time points [Day 0 （D0： prior to injection）, 3 h, D1, D2, D3, and D10] after TCPOBOP administration to obtain liver and blood samples. Using the RNA samples extracted from the liver, a comprehensive analysis was performed on the hepatic gene expression profiling of coagulation-related factors by real-time RT-PCR （fibrinogen, prothrombin, factors Ⅴ, Ⅶ, Ⅷ, Ⅸ, Ⅹ, Ⅺ, Ⅻ, ⅩⅢβ , plasminogen, antithrombin, protein C, protein S, ADAMTS13, and VWF）. The corresponding plasma levels of coagulation factors （fibrinogen, prothrombin, factors Ⅴ, Ⅶ, Ⅷ, Ⅸ, Ⅹ, Ⅺ, Ⅻ, ⅩⅢ, and VWF） were also analyzed and compared with their mRNA levels. RESULTS： Gavage administration of TCPOBOP （3 mg/kg body weight） resulted in a marked and gradual increase in the weight of the mouse livers relative to the total body weight to 220% by D10 relative to the DO （control） ratios. At the peak of liver regeneration （D1 and D2）, the gene expression levels for most of the coagulationrelated factors （fibrinogen, prothrombin, factors Ⅴ, Ⅶ, Ⅷ, Ⅸ,Ⅺ, Ⅻ, ⅩⅢβ, plasminogen, antithrombin, protein C, ADAMTS13, VWF） were found to be downregulated in a time-dependent manner, and gradually recovered by D10 to the basal levels. Only mRNA levels of factor X and protein S failed to show any decrease during the regenerative phase. As for the plasma levels, 5 clotting factors （prothrombin, factors Ⅷ, Ⅸ, Ⅺ, and Ⅻ） demonstrated a significant decrease （P 〈 0.05） during the regeneration phase compared with DO. Among these 5 factors, factor Ⅸ and factor Ⅺ showed the most dramatic decline in their activities by about 50% at D2 compared to the basal levels, and these reductions in plasma activity for both factors were consistent with our RT-PCR findings. In contrast, the plasma activities of the other coagulation factors （fibrinogen, factors Ⅴ, Ⅶ, ⅩⅢ, and VWF） were not significantly reduced, despite the reduction in the liver mRNA levels. Unlike the other factors, FX showed a temporal increase in its plasma activity, with significant increases （P 〈 0.05） detected at DI. CONCLUSION： Investigating the coagulation cascade protein profiles during liver regeneration by DH may help to better understand the basic biology of the liver under normal and pathological conditions.

Binding of EGF1 Domain Peptide in Coagulation Factor Ⅶ with Tissue Factor and Its Implications for the Triggering of Coagulation

The binding function of EGF1 domain peptide with tissue factor(TF)and its ability of triggering coagulation were explored.The TF expression model in vitro was established by lipopolysaccha-ride induction.The affinity of EGFP-EGF1 and TF expressing cells was analyzed by fluorescence microscopy and flow cytometry(FCM).The affinity of EGFP-EGF1 and rat soluble TF was quantitated by surface plasmon resonance(SPR).The ability of EGFP-EGF1 in triggering coagulation was tested by prothrombin time assay.The FCM res...

Polymorphisms in the genes for coagulation factor II,V,VII in patients undergoing coronary angiography

Objective: To determine whether polymorphisms in the genes for coagulation factor II,V, VII could predispose an individual to increase risk for coronary artery disease (CAD) and/or myocardial infarction (MI) in Chinese. Methods: We screened coagulation factor II(G20210A),V(G1691A),VII (R353Q and HVR4) genotype in 374 patients undergoing coronary angiography by polymerase chain reaction and restriction fragment length polymorphism (PCR RFLP) assay. Results: The R353Q and HVR4 genotype of the factor VII distribution was in accordance with Hardy Weinberg equilibrium. The frequencies of FVII genotype or allele did not show statistically significant differences between CAD group and controls or between male and female. The frequencies of the Q allele and (RQ+QQ) genotype were significantly higher among the CAD patients without myocardial infarction (MI) history than among those with MI history ( P <0.05). However, HVR4 polymorphism was not significantly different within groups. We only find one normal control of factorII(G20210A) mutation. No coagulation factor V(G1691A) mutation was found in the CAD patients and controls. Conclusion: The factor II(G20210A),V(G1691A) mutation is absent and may not be a major genetic factor for CAD and/or MI; the Q allele of the R353Q polymorphism of the factor VII gene may be a protective genetic factor against myocardial infarction in Chinese.

Acquired coagulation dysfunction resulting from vitamin Kdependent coagulation factor deficiency associated with rheumatoid arthritis: A case report

BACKGROUND Rheumatoid arthritis(RA)is a common chronic inflammatory autoimmune disease with the main clinical feature of progressive joint synovial inflammation,which can lead to joint deformities as well as disability.RA often causes damage to multiple organs and systems within the body,including the blood hemostasis system.Few reports have focused on acquired coagulation dysfunction resulting from vitamin K-dependent coagulation factor deficiency associated with RA.CASE SUMMARY A 64-year-old woman with a history of RA presented to our hospital,complaining of painless gross hematuria for 2 wk.Blood coagulation function tests showed increased prothrombin time,international normalized ratio,and activated partial thromboplastin time.Abnormal blood coagulation factor(F)activity was detected(FII,7.0%;FV,122.0%;and FX,6.0%),indicating vitamin K-dependent coagulation factor deficiency.Thromboelastography and an activated partial thromboplastin time mixed correction experiment also suggested decreased coagulation factor activity.Clinically,the patient was initially diagnosed with hematuria,RA,and vitamin K-dependent coagulation factor deficiency.The patient received daily intravenous administration of vitamin K120 mg,etamsylate 3 g,and vitamin C 3000 mg for 10 d.Concurrently,oral leflunomide tablets and prednisone were administered for treatment of RA.After the treatment,the patient's symptoms improved markedly and she was discharged on day 12.There were no hemorrhagic events during 18 mo of follow-up.CONCLUSION RA can result in vitamin K-dependent coagulation factor deficiency,which leads to acquired coagulation dysfunction.Vitamin K1 supplementation has an obvious effect on coagulation dysfunction under these circumstances.

Treatment of vitamin K-dependent coagulation factor deficiency and subarachnoid hemorrhage

BACKGROUND： In adults, vitamin K-dependent coagulation factor deficiency （VKCFD） increases in the recent years. We treated a VKCFD patient with subarachnoid hemorrhage, with favorable outcomes.METHODS： A 19-year-old male student with VKCFD was treated at our hospital. The initial treatment was injection of a large dose of vitamin K and fresh plasma, and then with oral high dose of vitamin K4.RESULTS： At 4 weeks after admission, the focus of hemorrhage subsided, neurological examination was normal, and the patient was discharged.CONCLUSIONS： VKCFD is rare and its diagnosis should be based on the history of the patient and the results of laboratory examinations. A large dose of vitamin K is the fi rst choice of treatment.

Preparation and Structure of a New Coagulation Factor XI Catalytic Domain for Drug Discovery

Human blood coagulation factor XI （FXI） is a key enzyme in the amplification phase of blood coagulation cascade, and is recognized as an important target for anti-coagulant development in recent years. We designed a new mutant form of FXIa catalytic domain rhFXI370-607 （N73Q-N113Q-C123S）, and report here the facile preparation, protein crystallization, and crystal structure of this protein. We highlight a few unique structural features of FXIa after comparison with the trypsin family serine proteases at sequence and structural levels. This work provides a foundation to develop new small molecular FXIa inhibitors with increased potency and specificity.

Maltose-binding Protein Improving the Crystallizability of C2 Domain of Human Coagulation Factor V

Human coagulation Factor V（FV）, together with Factor Xa, assembles to prothrombinase complex on activated cell surface, which converts prothrombin into thrombin, leading to fibrin deposition. The C2 domain of FV is believed to be a primary anchor for the assembly of pro- thrombinase on the cell surface, and was proposed as a target to intervene with pathological thrombotic events. We report here the crystal structure of the C2 domain of FV fused to maltose-binding protein（MBP）. The fusion tag of MBP is critical to generate the crystal for this study. There is no strong interaction between MBP and FVC2. The overall structure of FVC2 is similar to the previous FVC2 structures, suggesting the MBP fusion does not perturb the molecular structure of FVC2. This crystal form of FVC2 can be used for future study of molecular interaction between FVC2 and its inhibitors.

ABO Blood Groups and Their Relationship with Coagulation Factor VIII in Healthy Adults

Background: ABO blood group distribution defers with racial and geographic variations. They are related to diseases like cardiovascular diseases, cerebral thromboembolism. ABO blood group system may influence coagulation factor VIII which may increase the future risk of thrombosis. Aim: To assess the relation of ABO blood group with coagulation factor VIII in healthy adults. Material and Methods: A prospective type of analytical cross-sectional study was conducted in the Department of Physiology, Dhaka Medical College, Dhaka from July 2019 to June 2020. After obtaining ethical clearance, a total of 190 healthy adults were selected from different areas of Dhaka city based on inclusion and exclusion criteria, with ages ranging from 18 - 45 years. The subjects were interviewed and detailed history regarding personal, family, medical and drug were taken. Prior to sample collection, informed written consent was taken from the participants. Individuals of blood group A were selected as group A, blood group B as group B, blood group AB as group AB and blood group O as group O. Coagulation factor VIII was measured in the Department of Hematology and BMT Unit, Dhaka Medical College Hospital, Dhaka. Blood grouping was done in the Department of Physiology, Dhaka Medical College, Dhaka. Statistical Analysis: For statistical analysis, ONE way ANOVA followed by Bonferroni test were considered using SPSS 25.0 version. Results: In this study, blood group B was most common (33.2%). Coagulation factor VIII was significantly higher (p < 0.001) in blood group A (105.76% ± 11.82%), B (112.00% ± 15.02%), AB (109.80% ± 11.93%) than blood group O (82.00% ± 12.86%). No significant difference was observed among A, B and AB blood groups regarding coagulation factor VIII. Conclusions: It can be concluded that blood group A, B, AB individuals may have more chance of thrombosis due to significantly higher coagulation factor VIII than blood group O individuals.

Change of Coagulation Factor Ⅷ and Antithrombin Ⅲ Activity in Bank-Stored Blood

Coagulation factor Ⅷ and antithrombin Ⅲ activity were detected in 15 health donors. It was found that antithrombin Ⅲ activity decreased obviously 12 h after blood drawing. It lost 56 % of the activity at the 3rd day, and 70 % of the activity at the 7th day. FⅧ:c showed no obvious change after 24 h, until the 3rd day. It lost 40 %-60 % of the activity after 36 h and was reduced to the 30 % of the original activity at the 5th day. Our results suggested that at the 3rd day coagulation factor Ⅷ of bank stored blood can be used to replenish antithrombin Ⅲ, while bank stored blood in one day can be used to replenish FⅧ.

Extrahepatic synthesis of coagulation factor Ⅶ by colorectal cancer cells promotes tumor invasion and metastasis

Background Blood coagulation factor Ⅶ （FⅦ） is physiologically synthesized in the liver and released into the blood. Binding of FⅦ to tissue factor （TF） is related to the metastatic potential of tumor cells, also a significant risk factor in the development of hepatic metastasis in patients with colorectal cancer （CRC）. It has been found that some cancer cells can produce FⅦ extrahepatically. However, litte is known about FⅦ and CRC. We therefore hypothesized that CRC cells may synthese FⅦ, leading to tumor invasion and metastasis.Methods We detected the expression of FⅦ protein in 55 CRC specimens by immunohistochemical staining. The FⅦ mRNA in 45 of 55 CRC cases, 6 colon cancer cell lines and one hepatoma cell line was measured by real-time reverse transcription-PCR （RT-PCR）. Transwell invasion assays were performed to evaluate the changes of cell migration and invasion of LoVo cancer cells in vitro. We further observed the likely effectors regulated by the TF/FⅦa complex Western blotting assay.Results Extrahepatic synthesis of FⅦ was detected in the cytoplasm of 32 （58.2%） CRC specimens byimmunohistochemistry, but not in normal mucosa. Liver metastasis （P=0.003） and TNM staging （P=0.005） were significantly correlated with FⅦ antigen expression. The positive ratios in stages Ⅰ, Ⅱ, Ⅲ and Ⅳ were 33.3%, 40.0%,52.4% and 87.5%, respectively. The expression of FⅦ mRNA in CRC with hepatic metastasis was significantly higher than CRC without hepatic metastasis （5.33±2.88 vs. 1.47±0.51, P=0.03）. Ectopic FⅦa induced a slight increase （1.34-fold） in the number of migrating cells, which was inhibited by the specific TF antibody. The formation of TF/FⅦacomplex resulted in a marked increase in the expression of matrix metalloproteinases （MMP）-2 （3.5-fold） and MMP-9（4.7-fold） in a time-dependent and dose-dependent manner.Conclusions Extrahepatic synthesis of FⅦ by CRC cells may promote tumor invasion and metastasis. MMPs, as downstream effectors of TF/FⅦa signaling, facilitate the development of metastasis in colon cancer.

Association of coagulation factor Ⅶ with the risk of myocardial infarction in the Chinese

To elucidate the association of plasma factor Ⅶ coagulant activity (FⅦc) with the risk of myocardial infarction (MI) and to assess the influence of factor Ⅶ gene MspI polymorphism and lipid metabolism on FⅦc in the Chinese Methods A total of 137 patients with angiographically confirmed MI and 125 healthy individuals were evaluated retrospectively Plasma FⅦc was measured by one stage prothrombin time, and FⅦ genotype was determined after MspI digestion of polymerase chain reaction amplified genomic DNA Serum lipid levels were assessed by routine methods Results MI patients had significantly higher levels of FⅦc (119 5%±22 7% vs 99 9%±21 8%, P <0 01) and total serum cholesterol (5 80±1 06?mmol/L vs 5 53±1 08?mmol/L, P <0 05) than controls, but only FⅦc independently correlated with the risk of MI (OR=1 04, P <0 01) There were no significant differences in FⅦ genotype or allele frequency between patients and controls ( P >0 05) Subjects with the Gln353 allele were associated with significantly lower FⅦc levels than Arg353 homozygotes (99 7%±19 3% vs 111 4%±24 6%, P <0 05) Serum triglyceride was positively correlated with plasma FⅦc in both control ( r =0 25, P <0 01) and case ( r =0 87, P <0 01) groups, but this correlation was restricted to Arg/Arg genotype ( r =0 68, P <0 01) A significant correlation of total serum cholesterol with FⅦc only appeared in Arg/Arg homozygotes ( r =0 17, P <0 01) Conclusions Our findings support the role of plasma FⅦc as a risk factor for MI in Chinese Plasma triglyceride and FⅦ gene MspI polymorphism are two independent determinants of FⅦc Assay of this polymorphism will be helpful in determining who will benefit most from lipid lowing therapy

Polymorphisms of the coagulation factor Ⅶ gene and its plasma levels in relation to acute cerebral infarction differences in allelic frequencies between Chinese Han and European populations

Background Coagulation factor Ⅶ (F Ⅶ) levels in plasma are usually related to ischemic heart disease (IHD) and cerebral infarction shares many of the risk factors related to IHD. Is there any relationship between factor Ⅶ and cerebral infarction? We investigated the relationship between F Ⅶ and acute cerebral infarction and reported genotype frequencies and allelic frequencies of FⅦ gene polymorphisms in the Chinese Han population. Methods We recruited 62 patients with acute cerebral infarction confirmed by magnetic resonance imaging (MRI) from Ruijin Hospital,and 149 age-matched patients clinically free of vascular disease to act as controls. All of them were unrelated,and were from the Chinese Han population. FⅦ coagulant activity (FⅦc) was determined using an clotting assay,activated FⅦ (FⅦa) and FⅦ Ag were assayed using enzyme immunoassay kits. The FⅦ gene polymorphisms to be detected included-401G/T,-402G/A,5’F7A1/A2,IVS7 and R353Q. 5’F7 and IVS7 were revealed by means of a PCR and direct agarose gel electrophoresis. The rest were examined by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results The results showed that FⅦc,FⅦAg and FⅦa were higher in the acute cerebral infarction group than in the control group ( P <0.01, P <0.05, P <0.05,respectively). There were no significant differences in the genotype frequencies of FⅦ gene polymorphisms between the two groups. The allelic frequencies in the Chinese Han population were as follows: -401G/T (96.64/3.36), -402G/A (52.01/47.99),5’F7A1/A2(96.64/3.36),IVS7 H5/H6/H7/H8 (0.34/52.35/46.98/0.34) and R353Q (95.64/4.36). There were significant differences ( P <0.01, P <0.001, P <0.001, P <0.001, P <0.001,respectively) in these allelic frequencies between the Chinese Han and European populations. Conclusions The results indicate that increased plasma FⅦ levels may contribute to thrombosis in cerebral infarction. And there was no significant difference in genotype frequencies of these five FⅦ gene polymorphisms between the acute cerebral infarction and control groups. Moreover,these results showed that the frequencies of protective allele, including -401T,5’F7 A2 and 353Q were lower, but that -402A, which was previously found to be associated with increased plasma FⅦ levels,is higher in Chinese Han population.

Advances of Coagulation Factor XIII

Objective： To provide a comprehensive literature review on roles of coagulation factor XIII （FXIII） in coagulation, wound healing, neoplasm, bone metabolism, and pregnancy. Data Sources： All articles in PubMed with key words ＂Coagulation factor XIII＂, ＂wound＂, ＂＇leukeraia＂, ＂tumor＂, ＂bone,＂ and ＂pregnancy＇＂ with published date from 2001 to 2016 were included in the study. Frequently cited publications before 2000 were also included. Study Selection： We reviewed the role of FXIll in biologic processes as documented in clinical, animal, and in vitro studies. Results： FXIII, a nlember of the transglutaminase （TG） family, plays key roles in various biological processes. Besides its well-known function in coagulation, the cross-linking of small molecules catalyzed by FXIII has been found in studies to help promote wound healing, improve bone metabolism, and prevent miscarriages. The study has also shown that FXIII concentration level differs in the blood of patients with leukemia and solid tumors and offers promises as a diagnostic indicator Conclusions： FXIII has many more biologic functions besides being known as coagulation factor. The TG activity of FXIII contributes to several processes, including wound healing, bone extracellular matrix stabilization, and the interaction between embryo and decidua of uterus. Further research is needed to elucidate the link between FXIII and leukemia and solid tumors.

Polymorphisms in the coagulation factor Ⅶ gene and the risk of myocardial infarction in patients undergoing coronary angiography

Objective To investigate whether coagulation factor Ⅶ (FⅦ) polymorphisms play a role in the pathogenesis of coronary artery disease (CAD) and/or myocardial infarction (MI) in a series of Hans.Methods The Arg 353 Gln and HVR4 polymorphisms of FⅦ gene were determined in 374 patients undergoing selective coronary angiography by PCR and restriction fragment length polymorphism assay.Results The FⅦ genotype distribution was in accordance with Hardy-Weinberg equilibrium. The frequencies of FⅦ genotypes or alleles did not show significant differences between the CAD group and the controls or between the males and the females. The frequencies of carriers of the Gln 353 allele and (Arg/Gln+Gln/Gln) genotypes were significantly higher in the CAD patients without MI than in those with MI ( P =0.031,odds ratio 0.37,95% CI: 0.15-0.94). However,HVR4 polymorphisms were not significantly different between the two groups ( P >0.05).Conclusion Carrying the F Ⅶ Gln 353 gene may be a protective factor against MI in the Chinese Hans.

Molecular mechanism of microRNA125 regulating human coagulation factor IX gene with nonsense mutation

Objective To construct human coagulation factorⅨmini-gene(Mini-h F9)and some nonsense mutants,detect the levels of the Mini-h F9 mRNA,and analyze the molecular mechanism of microRNA125 regulating F9gene with nonsense mutation.Methods Three nonsense mutants were obtained by using PCR mutagenesis to ana-

Relationship between Acquired Deficiency of Vitamin K-dependent Clotting Factors And Hemorrhage

This study examined the changes of activities of vitamin K-dependent clotting factors(VKDCF) under various pathological conditions and explored the relationship between acquired deficiency of VKDCFs and hemorrhage.Clinical data of 35 patients who were diagnosed as having acquired deficiency of VKDCF were retrospectively analyzed.Coagulation factors involved in the intrinsic and extrinsic pathways were detected in these patients and 41 control subjects.The results showed that the average activities of VKDCFs were decreased in the patients in comparison to the control subjects and significantly increased after treatment of these patients with vitamin K and blood products.Multivariate regression analysis indicated that decreased activity of VKDCF was not an independent risk factor for bleeding disorders owing to deficiency or metabolic disturbance of vitamin K.It was concluded that acquired deficiency of VKDCF occurs under a variety of pathologic conditions and is closely associated with hemorrhagic events.Administration of vitamin K and transfusion of blood products containing high concentrations of VKDCFs helps alleviate the hemorrhagic diseases.

Factors predisposing to thrombosis after major joint arthroplasty

BACKGROUND Total joint arthroplasty is one of the most common options for end stage osteoarthritis of major joints.However,we must take into account that thrombosis after hip/knee arthroplasty may be related to mutations in genes encoding for blood coagulation factors and immune reactions to anticoagulants[heparininduced thrombocytopenia(HIT)/thrombosis].Identifying and characterizing genetic risk should help to develop diagnostic strategies or modify anticoagulant options in the search for etiological mechanisms that cause thrombophilia following major orthopedic surgery.AIM To evaluate the impact of patients’coagulation profiles and to study specific pharmacologic factors in the development of post-arthroplasty thrombosis.METHODS In 212(51 male and 161 female)patients that underwent primary total hip arthroplasty(100)or total knee arthroplasty(112)due to osteoarthritis during a period of 1 year,platelet counts and anti-platelet factor 4(PF4)/heparin antibodies were evaluated pre/postoperatively,and antithrombin III,methylenetetrahydrofolate reductase,factor V and prothrombin gene mutations were evaluated preoperatively.In a minimum follow-up of 3 years,196 patients receiving either low-molecular-weight heparins(173)or fondaparinux(23)were monitored for the development of thrombocytopenia,anti-PF4/heparin antibodies,HIT,and thrombosis.RESULTS Of 196 patients,32 developed thrombocytopenia(nonsignificant correlation between anticoagulant type and thrombocytopenia,P=0134.)and 18 developed anti-PF4/heparin antibodies(12/173 for low-molecular-weight heparins and 6/23 for fondaparinux;significant correlation between anticoagulant type and appearance of antibodies,P=0.005).Odds of antibody emergence:8.2%greater in patients receiving fondaparinux than low-molecular-weight heparins.Gene mutations in factor II or V(two heterozygotes for both factor V and II)were identified in 15 of 196 patients.Abnormal low protein C and/or S levels were found in 3 of 196(1.5%)patients,while all patients had normal levels of von Willebrand factor,lupus anticoagulant,and antithrombin III.Four patients developed HIT(insignificant correlation between thrombocytopenia and antibodies)and five developed thrombosis(two had positive antibodies and two were heterozygotes for both factor II&V mutations).Thrombosis was not significantly correlated to platelet counts or HIT.The correlation of thrombosis to antibodies,factor II,factor V was P=0.076,P=0.043,P=0.013,respectively.CONCLUSION Screening of coagulation profile,instead of platelet monitoring,is probably the safest way to minimize the risk of post-arthroplasty thrombosis.In addition,fondaparinux can lead to the formation of anti-PF4/heparin antibodies or HIT.