[Novel frame-shift mutation of 540 A deletion in GP IIb gene from a patient with Glanzmann thrombasthenia].

OBJECTIVE: To explore the molecular mechanism of Glanzmann thrombasthenia (GT). METHODS: All 45 exons of alphaIIb and beta3 subunit genes as well as their splicing sites were amplified by polymerase chain reaction(PCR) with 40 primer pairs, and then the PCR products were used to screen the gene mutation by single strand conformation polymorphism-polyacrylamide gel electrophoresis (SSCP-PAGE). The mutation was further confirmed by direct DNA sequencing. RESULTS: A DNA band alterated migration was detected after SSCP-PAGE. DNA sequencing showed that a base deletion within the band at the site of 540 in GPIIb gene(540A) was found. CONCLUSION: The frame-shift mutation caused by the deletion of 540A in GPIIb gene is a novel mutation which is a genetic defect in patients with GT.

[Study on platelet-associated tissue factor and its significance].

OBJECTIVE: To explore whether normal platelet contains tissue factor (TF), and the significance of platelet-associated TF (PATF). METHODS: Platelets were isolated by Sepharose 2B gel column. ELISA was used to detect the TF content in the lysates of washed platelets. Procoagulant activity of PATF was measured by one stage clotting time assay. The mRNA of TF was detected by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: A certain amount of TF antigen (16.37 +/- 6.39) ng/L was detected in the washed-platelet lysates. Upon activation by collagen, platelets released TF and caused a marked increase in TF level in plasma (P <0.05). Resting platelets had no TF procoagulant activity, while procoagulant activity of platelets activated by collagen increased significantly, which could be blocked by TF McAb and poor VII plasma. TF mRNA could not be detected in washed platelets. TF content in platelets from patients with coronary heart disease was significantly higher than that from normal controls (P < 0.05). Resting platelets from the patients showed a higher procoagulant activity, which could be inhibited by TF McAb. CONCLUSION: Platelets contain TF and the latter released by activated platelet was functionally active. Platelet itself might not synthesize TF. Protein content and procoagulant activity of PATF in patients with coronary heart disease were higher than that in controls. All these indicate that platelet may be involved in coagulation and thrombosis by releasing TF.

[Effect of angiotensin II on tissue factor expression in human peripheral blood monocytes and its mechanisms].

OBJECTIVE: To elucidate the effect of angiotensin II (AngII) on the expression of tissue factor (TF) by monocytes and its mechanisms. METHODS: Monocytes were isolated from healthy volunteers by Ficoll-Hypaque gradient and Percoll, and cultured in RPMI-1640. Procoagulant activity (PCA) was determined by one-stage clotting method, TF antigen by ELISA. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the TF gene mRNA. The levels of IkappaBalpha was detected by Western blot. Electrophoretic mobility shift assays (EMSA) were performed to evaluate the activity of NF-kappaB. RESULTS: AngII (10(-9) - 10(-7) mol/L) significantly increased monocyte PCA, TF antigen and TF mRNA expression in a dose and time dependent manner. Losartan (10(-6) - 10(-5) mol/L) significantly inhibited the effects of AngII on TF activity, antigen and mRNA expression in a dose-dependent effects. Staurosporine (2.5 x 10(-7) mol/L) and genistein (4 x 10(-5) mol/L) lowered TF level of monocytes (P < 0.05). Western blot analysis revealed that after exposure to AngII (10(-7) mol/L), IkappaBalpha level decreased at 15 min, reached nadir at 60 min, and recovered at 180 min. EMSA showed NF-kappaB binding activity increased at 15 min, reached peak at 60 min, and recovered at 180 min. Pyrrolidine dithiocarbamate (PDTC, 10(-4) mol/L), an inhibitor of NF-kappaB, or AT1R antagonist losartan (10(-5)mol/L) inhibited AngII-induced NF-kappaB translocation. CONCLUSIONS: AngII could induce the expression of TF in human monocytes, and this effect was mediated by AT1R. The PKC pathway played the most important role in AngII-induced TF expression. The activation of NF-kappaB was involved in TF expression in monocytes.

[Observation on tissue factor pathway during the onset of acute cerebral infarction].

OBJECTIVE: To establish the possible relationship between some coagulation factors and the onset of acute cerebral infarction (ACI). METHODS: The study population consisted of 71 patients with ACI confirmed by CT and 50 age-matched healthy volunteers. Blood samples were obtained during the onset period of ACI. Tissue factor (TF) and tissue factor pathway inhibitor (TFPI) activity in plasma were assayed with the chromogenic assay. Plasma TF and TFPI antigen were measured with enzyme linked immunoadsorbent assay (ELISA). Plasma F VII coagulation activity (F VII: C) and F VIII coagulation activity (F VIII: C) were developed in the one-stage system. Plasma prothrombin (FII) was determined with Ecarin assay. Plasma fibrinogen (Fbg) was measured with thrombin assay. Plasma antithrombin III activity (ATIII) was determined using heparin cofactor activity assay. RESULTS: Compared with the control, plasma TF activity and antigen in patients with ACI were significantly higher (both P<0.05). But plasma TFPI activity and antigen were remarkably lower in the ACI group (both P<0.05). Plasma F VII: C was significantly higher (P<0.01), and F VIII: C was markedly lower (P<0.05). Plasma FII was remarkably higher (P<0.01). Similarly the Fbg was significantly higher in the ACI than that in the control group (P<0.01), whereas ATIII was significantly lower (P<0.01). CONCLUSION: The initiation of TF pathway is contributed to the onset of ACI and the blood is in hypercoagulable state during the early period of ACI.

[Study on expression of cell surface L-selectin and soluble L-selectin in patients with acute leukemia].

To study the relationship between the level of the soluble L-selectin (sL-selectin) in plasma and surface L-selectin expression on leukemic cells and episode and state of illness in acute leukemia patients, the plasma level of sL-selectin was measured by a sandwich enzyme-linked immunosorbent assay, and the expressions of surface L-selectin and its gene (lyam-1) were detected by immunohistochemistry and RT-PCR. The results showed that the levels of sL-selectin were significantly higher in untreated and therapy-resistant acute leukemia patients, and expression of L-selectin mRNA and cell surface L-selectinin in untreated and NR patients were significantly lower than that in CR patients and control group (P < 0.05). The plasma levels of sL-selectin were significantly increased in patients with splenomegaly and hepatomegaly (extramedullary infiltration). The levels of sL-selectin were related to the clinical course of the acute leukemia patients. A significant correalation existed between expressions of L-selectin mRNA and surface L-selectin in acute leukemia patients (gamma = 0.782, P < 0.05). It is concluded that expression of L-selectin gene was down-regulated in level of mRNA and protein in acute leukemia patients and both changes were highly correlated. Monitoring of the plasma level of sL-selectin is possibly useful for early diagnosis of relapse and extramedullary infiltration in acute leukemia.