Lu Gao

St George Hospital, Sydney, New South Wales, Australia

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Publications (3)17.23 Total impact

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    ABSTRACT: Factor XI (FXI), a disulfide-linked covalent homodimer, circulates in plasma, and upon activation initiates the intrinsic/consolidation phase of coagulation. We present evidence that disulfide bonds in FXI are reduced to free thiols by oxidoreductases thioredoxin-1 (TRX-1) and protein disulfide isomerase (PDI). We identified that Cys362-Cys482 and Cys118-Cys147 disulfide bonds are reduced by TRX-1. The activation of TRX-1-treated FXI by thrombin, FXIIa or FXIa was significantly increased compared to non-reduced FXI, indicating that the reduced factor is more efficiently activated than the oxidized protein. Using a novel ELISA system, we compared the amount of reduced FXI in antiphospholipid syndrome (APS) thrombosis patients with levels in healthy controls, and found that APS patients have higher levels of reduced FXI. This may have implication for understanding the contribution of FXI to APS thrombosis, and the predisposition to thrombosis in patients with elevated plasma levels of reduced FXI.
    No preview · Article · Jun 2012 · Journal of Autoimmunity
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    ABSTRACT: Beta-2-glycoprotein I (β2 GPI) constitutes the major autoantigen in the antiphospholipid syndrome (APS), a common acquired cause of arterial and venous thrombosis. We recently described the novel observation that β2 GPI may exist in healthy individuals in a free thiol (biochemically reduced) form. The present study was undertaken to quantify the levels of total, reduced, and posttranslationally modified oxidized β2 GPI in APS patients compared to various control groups. In a retrospective multicenter analysis, the proportion of β2 GPI with free thiols in serum from healthy volunteers was quantified. Assays for measurement of reduced as well as total circulating β2 GPI were developed and tested in the following groups: APS (with thrombosis) (n=139), autoimmune disease with or without persistent antiphospholipid antibodies (aPL) but without APS (n=188), vascular thrombosis without APS or aPL (n=38), and healthy volunteers (n=91). Total β2 GPI was significantly elevated in patients with APS (median 216.2 μg/ml [interquartile range 173.3-263.8]) as compared to healthy subjects (median 178.4 μg/ml [interquartile range 149.4-227.5] [P<0.0002]) or control patients with autoimmune disease or vascular thrombosis (both P<0.0001). The proportion of total β2 GPI in an oxidized form (i.e., lacking free thiols) was significantly greater in the APS group than in each of the 3 control groups (all P<0.0001). This large retrospective multicenter study shows that posttranslational modification of β2 GPI via thiol-exchange reactions is a highly specific phenomenon in the setting of APS thrombosis. Quantification of posttranslational modifications of β2 GPI in conjunction with standard laboratory tests for APS may offer the potential to more accurately predict the risk of occurrence of a thrombotic event in the setting of APS.
    Full-text · Article · Sep 2011 · Arthritis & Rheumatology
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    Lu Gao · De-min Yu
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    ABSTRACT: Currently, there are still divergent opinions about the mechanisms of the impaired neovascularization in diabetic subjects. Due to the remarkable therapeutic effect of angiotensin-converting enzyme inhibititors (ACEIs) on the reduction of blood pressure and the protection of target organs, the clinical application of this kind of drugs is very widespread. However, it is still not clear about the role and related molecular pathway of this kind of drugs in the limbs' postischemic revascularization. It is of major therapeutic importance to resolve these questions. This study aimed to investigate the reasons of the impaired angiogenesis in the hind limbs of rats with diabetic ischemia, the role and related molecular mechanisms of ACEI in postischemic revascularization. Hind limbs ischemia was induced in diabetic rats by right femoral artery excision. Diabetic rats were randomly allocated to one of the following treatments for 4 weeks: ACEI by perindopril; perindopril in combination with a nitric oxide synthase (NOS) inhibitor; perindopril in combination with bradykinin (BK)-B1 receptor (B1R) antagonist or saline. The differences of angiogenesis, the mRNA and protein expression of endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF) and basic fibroblast (bFGF), constitutive nitric oxide synthase (cNOS) activity and nitric oxide (NO) content were observed after treatment. In non-ischemic hind limbs, no significant changes in capillary density, or the mRNA and protein expression of eNOS, VEGF and bFGF, or the NO content and the cNOS activity were observed among all groups. On the contrary, in ischemic hind limbs, the capillary density in diabetic rats decreased by 27% when compared with the control rats, so did the mRNA and protein expression of eNOS, VEGF and bFGF, or the NO content and the cNOS activity (P < 0.05). The capillary density was increased by 1.65-fold in the perindopril treatment group in reference to untreated diabetic rats. Moreover, administration of perindopril enhanced the mRNA expression of eNOS, VEGF, and bFGF by 1.45-, 1.44-, and 1.33-fold, increased the protein content of the above indices by 1.55-, 1.30- and 1.50-fold compared with the untreated diabetic rats respectively. Perindopril also increased NO content and cNOS activity to 1.33- and 1.38-fold of that in untreated diabetic rats. The combination of BK-B1R antagonist significantly decreased the above indices (P < 0.05). In contrast, the combination of NOS inhibitor decreased the expression of eNOS and bFGF, the NO content and the cNOS activity, while the expression of VEGF did not change. Diabetes mellitus reduces the neovascularization, related growth factors expression and activity in the diabetic rat ischemic legs model. Treatment of perindopril improves postischemic revascularization. This effect is mediated, at least in part, by the BK-B1R-related pathway, and the activation of VEGF/eNOS/bFGF signals may be involved in the pro-angiogenic effect.
    Preview · Article · Nov 2008 · Chinese medical journal