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Objective: To investigate the susceptibility of von Willebrand factor (VWF) type 2A mutant A1500E to proteolysis by metalloprotease ADAMTS13 and to provide the direct supports for the pathogenesis of VWF mutation A1500E responsible for von Willebrand disease (VWD) type 2A., Methods: Recombinant wild-type VWF (WT-VWF) and A1500E mutant VWF transiently expressed on transfected HeLa cell lines. Expression media were collected and concentrated, then cleaved directly by recombinant ADAMTS13 (rADAMTS13). Compared with WT-VWF, the susceptibility of A1500E mutant VWF to proteolysis by ADAMTS13 was analyzed using SDS-agarose gel VWF multimers analysis., Results: In vitro the expression of VWF:Ag in the supernatants of WT-VWF and A1500E mutant VWF were 1.10 U/ml and 0.78 U/ml, respectively, while VWF:Ag in cells lysates of A1500E mutant VWF was 90.6% of that of WT-VWF. The SDS-agarose gel VWF multimers analysis showed that there were no differences between WT-VWF and A1500E mutant VWF. The A1500E mutant VWF could be efficiently cleaved by ADAMTS13 under static condition without denaturants such as urea and guanidine HCl. VWF multimeric analysis showed that high and intermediate molecular weight multimers dramatically decreased while low molecular weight multimers obviously increased. Conversely, WT-VWF could not be cleaved by ADAMTS13 under the same condition., Conclusion: The A1500E mutation resulted in VWF more susceptible to ADAMTS13-dependent proteolysis, which belonged to VWD type 2A group 2 mutation.

Objective: To construct the expression vectors of vWF73 and vWF114 fragments of von Willebrand factor (vWF) A2 domain, and to express glutathione S-transferase (GST) fusion proteins in E. coli, and to explore their values in measuring ADAMTS13 activity as substrates., Methods: The DNA fragments encoding vWF73 and vWF114 were generated using PCR and separately cloned into pGEX-6P-1, a Schistosoma japonicum GST fusion expression vector. The expression of GST-vWF73-H and GST-vWF114-H was induced in liquid culture, followed by purification with Ni-NTA agarose column. The cleavage of two GST fusion proteins by recombinant ADAMTS13 (rADAMTS13) or plasma from normal individuals and thrombotic thrombocytopenic purpura (TTP) patients were identified by Western blot. Based on an enzyme-linked immunosorbent assay (ELISA) with anti-GST and anti-His monoclonal antibodies, GST-vWF73-H and GST-vWF114-H were used to measure plasma ADAMTS13 activity as substrates., Results: Two small molecular substrates of ADAMTS13, GST-vWF73-H and GST-vWF114-H, are expressed and purified, which could be specifically cleaved by rADAMTS13 or plasma from healthy individuals, but not by plasma from congenital or idiopathic TTP patients. An ELISA assay was established to detect plasma ADAMTS13 activity using GST-vWF73-H and GST-vWF114-H as substrates., Conclusions: Two GST fusion proteins in vWF A2 domain, vWF73 and vWF114, were expressed effectively using a prokaryotic expression system and could be used to detect ADAMTS13 activity as substrates.

Objective: To establish NB4/VEGF-C cells xenograft in nude mice model, and explore the effect of VEGF-C on hematological malignancies, Methods: NB4/VEGF-C or NB4/pcDNA3.1 cell lines were established by transfecting the recombinant pcDNA3.1-VEGF-C plasmid and the vacant pcDNA3.1 vector into NB4 cells. The recombinant VEGF-C was identified by RT-PCR and Western blotting. Eighteen male BALB/c nude mice aged 4 - 5 weeks were equally divided into two groups. Mice irradiated by 4 Gy ⁶⁰Co were subcutaneously injected with 1 × 10⁷NB4/VEGF-C or NB4/pcDNA3.1 cells into one side of axilla. The volumes of xenograft tumor was evaluated according to L × t² × 0.52. Microvessel density (MVD) on the xenograft tumor section was detected by IHC with VWF antibody., Results: NB4 cell xenograft tumors were developed in all mice of both the two groups. The growth of NB4/VEGF-C cells in nude mice was faster than in controls. There were statistically significant differences in the volume and weight of xenograft tumor between NB4/VEGF-C and NB4/pcDNA3.1 cell groups \[(631.44 ± 114.42) mm³ vs (491.22 ± 70.05) mm³\] (P = 0.006) and \[(321.78 ± 27.84) mg vs (288.57 ± 40.12) mg\] (P = 0.031), respectively. MVD in xenograft tumor of NB4/VEGF-C cells \[(50.8 ± 11.7)/mm²\] was higher than that in controls \[(18.9 ± 7.0)/mm²\] (P = 0.021). The Bcl-2 protein level in NB4/VEGF-C cells xenografts was higher than that in controls., Conclusion: VEGF-C could promote proliferation of NB4 cells by inducing angiogenesis and inhibit cells apoptosis by upregulating antiapoptotic Bcl-2 protein expression in NB4 cells xenograft tumor.

Objective: To study the influence of C-terminal domain of ADAMTS13 on its cleaving activity., Methods: The full-length wild-type (WT) and C-terminal domain truncated type (TT, TSP8 + CUB domains were deleted) of human ADAMTS13 recombinant protein were transfected into and permanent expressed on Hela cells. Western blot and R-CBA were used to directly detect the activities of the two recombinant proteins under the static and stressed condition respectively. ELISA was used to compare the binding abilities of the two proteins by coating with vWF., Results: The recombinant proteins were identified by Western blot with anti-his-tag or anti-ADAMTS13 antibodies. With pretreatment of 1.5 M urea, the enzyme activity of TT was significantly higher than that of WT, and so did in binding ability with vWF While, only WT could cleave vWF under high stress., Conclusion: The distal carboxyl-terminal TSP8 together with CUB domains of ADAMTS13 may affect the enzyme activity by regulating the binding of ADAMTS13 to vWF in different conditions, and they are very important for the enzyme activity under high stress force condition.

Objective: To analyze the phenotype and genotype of a family with inherited dysfibrinogenemia., Methods: Assays of coagulation, including activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT), were carried out with Stago Compact in the proband and his family members. The activity and antigen of fibrinogen in plasma were determined by Clauss and immunoturbidimetry, respectively. Fibrinogen and its constituent were analyzed by Western blot with nonreducing 4%-20% SDS-polyacrylamide gel electrophoresis (PAGE). All exons and exon-intron boundaries of fibringen genes FGA, FGB and FGG were analyzed by PCR and then direct sequencing., Results: The proband had normal APTT and PT, but prolonged TT. The activity of fibrinogen in plasma was decreased while its antigen level was normal. These abnormalities were also found in his mother and a sister. Genetic analysis revealed heterozygous G1233A in the exon 2 of FGA originating from his mother, which resulted in Arg16His missense mutation., Conclusion: Inherited dysfibrinogenemia was caused by Arg16His mutation in exon 2 of FGA, and this is the first case reported in a Chinese family.

Objective: To investigate the effects of Annexin II (AnxA2) gene silencing by siRNA on proliferation and invasive potential of lymphoma cell line Jurkat cells., Methods: A synthesized siRNA duplex targeting to AnxA2 was transfected into Jurkat cells. Transfection efficiency was analyzed by real-time PCR and flow cytometry. MTT assay for cell proliferation and transwell plates for invasive potential were performed., Results: Compared with the negative controls, the cell proliferation inhibitory rate of the AnxA2 siRNA transfected Jurkat cells was significantly increased at 24 h, 48 h and 72 h [(17.4 +/- 2.3)%, (22.4 +/- 3.8)%, (37.6 +/- 1.5)% vs (-1.3 +/- 5.1)%, (-5.5 +/- 4.4)%, (-10.8 +/- 5.5)%, respectively, P<0.05]. The cell invasive potential of the transfected Jurkat cells was inhibited remarkably at 48 h (11.3 +/- 4.2 vs 54.3 +/- 8.7, P<0.01)., Conclusion: AnxA2 gene silenced by siRNA can inhibit the proliferation and the invasive potential of Jurkat cells remarkably.

Objective: To develop a monoclonal antibody (mAb) directed to FVIII C2 domain and investigate its effect on FVIII activity., Methods: FVIII C2 protein was expressed in E. coli and purified. A murine antihuman FVIII C2 domain mAb SZ-132 was developed by standard hybridoma technology and characterized. In coagulation assays, different concentrations of SZ-132 were incubated with freshly collected pooled human plasma and the residual activity of FVIII and activated partial thromboplastin time (APTT) were determined. The effects of SZ-132 on rhFVIII binding to purified human vWF, phosphatidylserine (PS) and platelets were assessed by enzyme linked immunosorbent assays (ELISA)., Results: SZ-132 could inhibit FVIII procoagulant activity in a dose-dependent manner within the concentrations of 0-25 microg/ml and the FVIII activity was completely inhibited on above 25 microg/ml. It could also prevent rhFVIII from binding to vWF, PS and platelets., Conclusions: SZ-132 is a neutralizing mAb against FVIII C2 domain and can inhibit FVIII procoagulant activity by preventing FVIII from binding to vWF and PS.

Objective: To investigate the ADAMTS13 antigen levels and activity in patients with acute myocardial infarction (AMI) and acute ischemic stroke (AIS), and explore its significance in these diseases., Methods: ADAMTS13 activity levels were detected by a new developed Frests-vWF73 kit, ADAMTS13 antigen levels by ELISA kit, and vWF multimers by electrophoresis., Results: ADAMTS13 antigen in normal control, AMI and AIS was (878 +/- 198), (618 +/- 188) and (702 +/- 155) U/L, and ADAMTS13 activity was (81.7 +/- 13.9)%, (59.2 +/- 22.1 )% and (65.4 +/- 15.8)%, respectively, being significantly decreased in AMI and AIS patients., Conclusion: ADMATS13 might involve in arterial infarction diseases.

Objective: To prepare anti-von Willebrand factor A3 (vWF-A3) domain monoclonal antibodies(mAbs) which block vWF-A3 binding to collagen, and characterize their biochemical properties and functions., Methods: BALB/c mice were immunized with purified recombinant vWF-A3 protein (rvWF-A3). Murine anti-human vWF-A3 mAbs were developed by standard hybridoma technology and identified with ELISA. The recognition of the mAbs with rvWF -A3 and reduced human vWF was identified by Western-blot. The effect of mAbs on binding of purified human vWF to human placenta or calf skin collagen III was studied with collagen binding inhibition test., Results: A group of 30 murine anti-human vWF-A3 mAbs was obtained, from which 2 clones were identified as inhibitory ones and designated as SZ-123 and SZ-125. SZ-123 and SZ-125 could react specifically with human vWF and rvWF-A3 respectively, while neither of them reacted with rvWF-A1 and rvWF-A2. Western-blot showed that SZ-123 and SZ-125 could recognize a 27 x 10(3) band of rvWF-A3 and 2 reduced human vWF bands at 250 x 10(3) and 170 x 10(3). SZ-123 and SZ-125 not only inhibited the binding of purified human vWF (1.5 and 3.0 microg/ml) to human type III collagen and to calf skin collagen III in a dose dependent manner, but also inhibited the binding of plasma vWF from human, rhesus monkeys or Beagle dogs to the two collagens., Conclusion: SZ-123 and SZ-125 are neutralizing mAbs against vWF-A3 domain and may have therapeutic potential as an antithrombotic agent.

Objective: To explore the biological effect on NB4 cells proliferation, all-trans retinoic acid (ATRA) inducing differentiation and resistance to apoptosis by vascular endothelial growth factor (VEGF)-C cDNA transfection., Methods: The recombinant eukaryotic expression plasmid pcDNA3.1-VEGF-C and the vacant pcDNA3.1 vector were introduced separately into NB4 cells by lipofectamine mediation. The positive clones were screened by G418 and identified by reverse transcriptase-PCR (RT-PCR) and Western blotting. The proliferation capacity of NB4/VEGF-C cells was analysed by MTT assay and colony forming assay in vitro. After NB4/VEGF-C cells were induced by ATRA, the expression level of C/EBPalpha gene, CD11b on cells surface and morphological alteration were analysed by real-time quantitative PCR (RQ-PCR), flow cytometry (FCM), and Wright-Giemsa staining, respectively. FCM Annexin V-FITC/PI dual labeling technique was performed to investigate the etoposide (Vp16) induced NB4/VEGF-C cells apoptosis and bcl-2 gene expression level in these cells was analysed by RQ-PCR. The NB4/pcDNA3.1 cells was used as control in the above experiments., Results: A stable NB4 cell line that secrets VEGF-C and its control lines were established. The proliferation capacity of the former was stronger than that of the latter. The expression level of C/EBPalpha gene of NB4/VEGF-C cells on ATRA treatment was only 1/32 that of NB4/pcDNA3.1 cells. The CD11b level and the degree of differentiation of NB4/VEGF-C were weaker than that of NB4/pcDNA3.1 cells. The percentage of apoptotic NB4/VEGF-C cells induced by Vp16 [(7.20 +/- 2.52)%] was significantly lower than that of NB4/pcDNA3.1 cells [(16.07 +/- 3.58)%] (P = 0.005), but the bcl-2 gene expression level of NB4/VEGF-C cells is 2.28-fold that of NB4/pcDNA3.1 cells., Conclusion: The VEGF-C via VEGFR-3 signaling pathway could promote the proliferation of leukemic cells by autocrine pathway and inhibit the cell differentiation mediated by ATRA and chemotherapy-induced apoptosis. VEGF-C/VEGFR-3 signaling loops might play an important role in disease progression and be potential therapeutic target for the treatment of leukemias.

Objective: To investigate the antigen levels and activity of von Willebrand factor cleaving protease ADAMTS13 in thrombotic thrombocytopenic purpura (TTP) patients and carriers., Methods: 28 samples from 13 TTP patients and 10 samples from the carriers were examined. The activity of ADAMTS13 was measured by residue collagen binding assay, and antigen by a newly developed sandwich ELISA., Results: The mean ADAMTS13 level in Chinese normal controls (CN) was (600.93 +/- 145.36) mU/ml (n = 26) comparable to the level (1000 mU/ml) in pooled normal Caucasian plasma, and the activity was (74.79 +/- 11.81)%. Both the antigen level and activity of ADAMTS13 in congenital TTP patients either before plasma exchange (pre-PE) or interval relapse were quite lower than those in normal control, but were increased after PE (post-PE). The antigen was (331.40 +/- 109.85) mU/ml (P < 0.01, n = 10), and activity was (66.79 +/- 12.82)% (P > 0.05). The ADAMTS13 levels pre-PE in idiopathic TTP was (98.7 +/- 82.08) mU/ml (n = 11, P < 0.01), and that post-PE was up to (449.4 +/- 232.33) mU/ml (P < 0.01, n = 10). The activity of ADAMTS13 in patients pre-PE and post-PE were (22.23 +/- 19.07)% (P < 0.01) and (60.92 +/- 22.33)% (P > 0.05) respectively. In a secondary TTP patient the ADAMTS13 antigen was much higher than that in CN, and the activity was 6.00%., Conclusion: The antigen and activity of ADAMTS13 in most TTP patients pre-PE are deficient, and these two indices in most TTP patients are paralleled. The reason for ADAMTS13 deficiency is congenital shortage or clearance by immune system, but it is unknown that why in some patients the ADAMTS13 antigen is extremely high but its activity is quite low.

Objective: To identify the genetic defect of inherited coagulation factor (F) deficiency in a Chinese family and to explore its molecular mechanism., Methods: The activity and antigen of plasma F were measured by photometric test and enzyme-linked immunosorbent assay, and rocket-electrophoresis, respectively. All the exons and exon-intron boundaries of the FA subunit gene were amplified by PCR and then DNA sequencing was performed. Restriction endonuclease analysis was used for the PCR products of the family members and 80 healthy donors to exclude gene polymorphism., Results: Rapid dissolution of the proband's fibrin clot occurred within 30 minutes, and antigen of his plasma F was significantly decreased, two compound heterozygous missense mutations (a C to T transition at nucleotide 177,246 which caused Arg703Trp, and a A to G transition at nucleotide 177,286 which caused His716Arg) in exon 15 of FA subunit gene were found. The possibility of gene polymorphism was excluded by restriction endonuclease analysing. Each of these two missense mutations was respectively found in his mother and father. Molecular modeling based on 3D crystallographic data predicted that the mutant protein decreased stability and was likely to be rapidly degraded., Conclusions: The inherited F deficiency in the Chinese family is caused by two compound heterozygous missense mutations-Arg703Trp and His716Arg in the FA subunit, which to our knowledge, are reported for the first time.

Objective: To investigate the gene mutations of ADAMTS13 in a highly suspected hereditary thrombocytopenic purpura (TTP) patient, and then make a progressive diagnosis and adjust the plan of therapy., Methods: ADAMTS13 activity and inhibitor were determined by residual-collagen binding assay during several episodes. Genomic DNA extracted from the proband's peripheral blood was used for amplification of 29 exons and exon/intron boundaries of ADAMTS13 by PCR. The PCR products were screened by direct sequencing and the gene alterations were further confirmed by direct sequencing in her family members., Result: The activity of the proband's ADAMTS13 was significantly reduced while no inhibitor was found. Two novel missense mutations were found in the TSPI repeated motif domain of ADAMTS13. In both mutations, thymine substituted for cytidine, resulting in the substitution of leucine for serine in nt 2708, exon 21 (codon S903L), and tryptophan for arginine in nt 3283, exon 25(codon R1095W). These two mutations were revealed as each heterozygote in the proband's parents., Conclusion: The deficiency of ADAMTS13 caused by two homozygote missense mutations might be responsible for episode of this TTP patient.

Objective: To identify the genetic defect underlying congenital afibrinogenemia in a Chinese family., Methods: Plasma fibrinogen (Fg) was assessed by both Clauss method and immunonephelometry. Genomic DNA was isolated from peripheral blood of the proband and 13 members of her family. All the exons and exon-intron boundaries of the three fibrinogen genes (FGA, FGB, FGG) were amplified by PCR followed by direct sequencing. Restriction endonuclease analysis was performed for the PCR products of the family members and 50 healthy donors to exclude gene polymorphism., Results: No Fg was detected in the plasma of the proband and her father by Clauss method, while low levels (< 0.02 g/L) were detected by immunonephelometry. A homozygous C to T mutation was found in the two cases at nucleotide 3108 in exon 4 of FGA gene, resulting in a null mutation which encoded severely truncated alpha-chains owing to its premature termination at the Gln 150 codon. The C-->T mutation eliminated a unique recognition site for restriction enzyme RsaI. The PCR amplified fragments of the proband and her father could not be digested by RsaI, showing that they are homozygous. Her mother and some family members are heterozygous at this site since the fragment could partly be digested, while the same fragment of controls could be completely digested as expected., Conclusion: The Gln (CAG)-->150stop (TAG) nonsense mutation in FGA gene is a novel genetic defect of congenital afibrinogenemia which, to our knowledge, has not been described before.

Objective: To investigate the T13254C polymorphism frequency in GPVI gene among Chinese Han population and its relevance to the arterial thrombotic diseases., Methods: The enrolled population in this study consisted of 314 healthy subjects and 274 patients with myocardial or cerebral infarctions. GPVI T13254C genotypes were determined by PCR amplification of a 355 bp fragment encompassing exon 5 of GPVI gene, followed by Msp I digestion of the product. The digested products were analyzed in 15% polyacrylamide gel electrophoresis (PAGE)., Results: The frequencies of the T allele and C allele in the T13254C polymorphism were 0.9809 and 0.0191, respectively, with a frequency of heterozygous of 0.0319, which were significantly different from those reported in western population (P < 0.01). As compared with controls, no significant difference in T13254C genotype distribution was found in the arterial thrombotic diseases group., Conclusion: The GPVI T13254C polymorphism appears in a low frequency in Chinese Han population. No relationship is found between T13254C polymorphism and the risk for thrombotic diseases.

Objective: To report a patient with congenital plasminogen activator inhibitor-1 (PAI-1) deficiency and explore its molecular mechanism., Methods: The activities of tissue plasminogen activator (tPA), alpha(2) antiplasmin (alpha(2)AP) and PAI-1 were measured by the methods of chromogenic substrate, the antigens of tPA and PAI-1 were measured by ELISA. PAI-1 gene was studied by PCR product sequencing and restriction endonuclease ana-lysing., Results: In the present patient, the euglobulin clot lysis time was 70 minutes and was corrected to normal range after added 50 ng/ml PAI-1 to his plasma. The activities of t-PA, alpha(2)AP, and factor were normal; the activity and antigen of PAI-1 in plasma were both significantly decreased. Nucleotide sequence analysis revealed that the patient had a heterozygous missense mutation in exon 2, a G to A transition at nucleotide 43. The possibility of gene polymorphism was excluded by restriction endonuclease analysing., Conclusions: It is the first patient with congenital PAI-1 deficiency reported in China. The PAI-1 deficiency in the patient may be caused by compound heterozygosity, one of which is the G to A transition at nt43, a new mutation in congenital PAI-1 deficiency.