Napaporn Archararit

Risk factors of venous thromboembolism in thai patients.

Venous thromboembolism (VTE) has been reported to be less common among Thais than Caucasians. Whether this observation reflects genetic or environmental factors, or both, is uncertain. To identify genetic and acquired risk factors of Thai patients with VTE, we enrolled in the study 105 consecutive Thai patients (34 men, 71 women) who had an objectively confirmed history of VTE. A complete clinical summary was obtained from each patient, with emphasis on personal and family history of VTE, as well as circumstantial vascular risk factors (surgery, immobilization, pregnancy, postpartum condition, trauma, oral contraceptive use, and malignancy). Of the 105 patients, 19% were found to have a malignancy. The mean age at the time of the first thrombotic episode was 52.1 years (range, 29–76 years), compared with 42.6 years (range, 17–82 years) for the patients without malignancy. Of the 85 patients without malignancy, 12.3% had protein S deficiency, 8.9% had protein C deficiency, 4.7% had antithrombin deficiency, 10.4% had antiphospholipid antibody, 30.4% had an elevated factor VIII level, 26.8% had an elevated factor XI level, 5.3% had hyperhomocysteinemia, and 16.5% were on oral contraceptives before the thrombotic episode. Factor V Leiden, the G20210A prothrombin gene mutation, and homozygosity for the C677T methylenetetrahydrofolate reductase (MTHFR) gene variant were not found. The VTE in 7.1% of the patients was considered to be secondary to recent surgery, trauma, and/or immobilization. Compared with studies of Caucasian patients, there were significant differences in the risk factors for VTE, with protein S deficiency and protein C deficiency being more common in the Thai patients. In contrast, factor V Leiden, the G20210A prothrombin gene mutation, and the C677T MTHFR gene mutation are not genetic risk factors among Thai patients with VTE. Malignancy and the use of oral contraceptives were the most common acquired risk factors for VTE in the Thai patients.

Activation of mononuclear phagocytes and its relationship to asplenia and phosphatidylserine exposing red blood cells in hemoglobin E/β-thalassemia patients.

Aged or abnormal red blood cells with exposed phosphatidylserine (PSRBCs) are cleared from the circulation by splenic macrophages. In asplenic patients, other mononuclear phagocytic cells in tissues and in circulation may function in this capacity. To better understand these changes and the relationship among splenic status, PS-RBCs, blood monocytes, and serum tumor necrosis factor (TNF-α), a product of mononuclear phagocyte activation, patients with hemoglobin E/β-thalassemia (E/β-Thal) were studied. Whole blood of 20 nonsplenectomized, 20 splenectomized E/β-Thal patients, and 20 healthy subjects was assayed for PS-RBCs; for monocytes, activated monocytes, and monocyte response to lipopolysaccharide stimulation; and serum was assayed for TNF-α. Asplenic E/β-Thal patients had significantly increased (P < 0.05) amounts of PS-RBCs, monocytes, activated monocytes, and levels of serum TNF-α. The amount of PS-RBCs correlated with levels of serum TNF-α, but the amount of activated monocytes did not correlate with either the amount of PS-RBCs or levels of serum TNF-α. Monocyte response to lipopolysaccharide stimulation in asplenic patients was not as efficient as in the other patients or in normals (77 vs. 404, and 304 folds increment, respectively). The results suggest that splenectomy in E/β-Thal patients led to an increased amount of PSRBCs and activation in the mononuclear phagocytic system.

Normalized coagulation markers and anticoagulation proteins in children with severe β-thalassemia disease after stem cell transplantation.

The hypercoagulable state is well recognized in patients with severe β-thalassemia disease. One of the mechanisms of chronic hypercoagulable state is the abnormal expression of phosphatidylserine on red blood cells (RBC). This study aimed to determine the coagulable state in patients with severe β-thalassemia disease following successful stem cell transplantation (SCT). Subjects were classified into three groups: normal controls (NC), β-thalassemia disease receiving regular transfusion (Thal-RT) and β-thalassemia disease post SCT (Thal-SCT). Sixty eight subjects, aged 3-17years, consisting of 21 NC, 28 Thal-RT and 19 Thal-SCT were enrolled. After SCT, the annexin V level in Thal-SCT was normalized. At the median follow-up time of 70.3 (50.9-84.2) months after SCT, the levels of coagulation markers (thrombin antithrombin complex, prothrombin fragment and D-dimer) and anticoagulation proteins (protein C, S and antithrombin activities) returned to the levels similar to controls.

Intravascular Hemolysis, Vascular Endothelial Cell Activation and Thrombophilia in Splenectomized Patients with Hemoglobin E/β-Thalassemia Disease

The relationship between asplenia and thrombophilia in β-thalassemia disease patients is not yet completely understood. One hundred and ten adult hemoglobin (Hb) E/β-thalassemia (E/β-Thal) disease outpatients, dichotomized according to the presence or absence of the spleen, were prospectively studied for evidence of intravascular hemolysis (IVH) and vascular endothelial cell (EC) activation. Biomarkers of IVH (serum cell-free Hb), EC [soluble E-selectin (sE-selectin) and soluble vascular cell adhesion molecule 1 (sVCAM-1)], platelet and EC [soluble P-selectin (sP-selectin)], inflammation [high-sensitivity C-reactive protein (hs-CRP)], and coagulation [thrombin-antithrombin complexes (TAT)] activation, as well as other selected blood tests were determined. The 61 splenectomized patients had a more severe hemolytic disease and higher levels of cell-free Hb and ferritin (p = 0.003), sE-selectin, sP-selectin, hs-CRP, and TAT (p < 0.05). However, serum levels of sVCAM-1 were not different between the two groups. The findings suggested IVH and EC activation. Together with chronic iron overload and chronic low-grade inflammation activation, the findings extend our understanding of the mechanism of thrombophilia in splenectomized E/β-Thal disease patients.

Specificity and sensitivity of anti-β2-glycoprotein I as compared with anticardiolipin antibody and lupus anticoagulant in Thai systemic lupus erythematosus patients with clinical features of antiphospholipid syndrome

Antibodies to β2-glycoprotein I (anti-β2-GPI) have been reported to have stronger association with clinical antiphospholipid syndrome (APS) than anticardiolipin antibodies (aCL) and lupus anticoagulant (LAC). We investigated the sensitivity and specificity of ELISA for anti-β2-GPI in Thai systemic lupus erythematosus (SLE) patients with clinical features of APS and compared the results with IgG/IgM aCL and LAC to find the test with the best association. The hospital records of 151 Thai SLE patients whose sera had been sent for either IgG/IgM anticardiolipin antibodies or lupus anticoagulant testing were reviewed. Sera of patients either without complete clinical records or those with APS-related manifestations other than vascular thrombosis and pregnancy morbidity (according to the international consensus statement on preliminary classification criteria for definite APS) were excluded. For the remaining subjects (112 patients), their sera were tested for anti-β2-GPI antibody, IgG and IgM anticardiolipin, and lupus anticoagulant. The sensitivity and specificity of each method were compared by using the chi-square test. Among the 112 (74.2%) SLE patients in the study, 35 (31.3%) presented with preliminary clinical criteria for APS (i.e., vascular thrombosis and pregnancy morbidity) whereas 77 (68.7%) did not. The sensitivity and specificity of anti-β2-GPI determination were 57.1 and 79.2%, respectively, whereas those of IgG aCL were 25.7 and 94.8%, of IgM aCL were 5.7 and 98.7%, and of LAC were 44.8 and 77.3%, respectively. The accuracy of the four tests showed similar association with clinical APS (accuracy of test = 72.3, 73.2, 69.6, and 68.3%, respectively). Concerning the sensitivity, specificity, and difficulty of the methods, the combination of anti-β2-GPI and IgG aCL tests was the best for the diagnosis of APS in Thai SLE patients.

Pulmonary artery pressure correlates directly with spleen volume in non-splenectomized hemoglobin E/β-thalassemia patients.

ratory features of the two groups are different [7] , they should affect the three governing factors of PAP differently. While a huge spleen with sinusoidal dilatation and associated increased blood volume, together with lack of evidence of thrombophilia [7] , in non-splenectomized patients would mainly affect the cardiac output, the thrombophilia-associated thrombotic pulmonary arteriopathy in splenectomized counterparts would lead to increased PVR [5] . Because right heart catheterization, which is an invasive procedure, is required to verify this, a less informative transthoracic echocardiography is routinely utilized, particularly to estimate PAP. To establish the relationship of PAP with cardiac output in non-splenectomized patients, blood volume results are helpful. However, our experience with blood volume measurement by isotopic dilution technique is far from satisfactory, particularly in patients with red blood cell (RBC) disorders. Therefore, spleen volume as determined by a CT scan was used as a surrogate for the altered blood volume to accommodate the marked sinusoidal dilataPulmonary arterial hypertension (PAH) in patients with thalassemia/hemoglobinopathy is a clinical entity which is not uncommon though often overlooked due to its subtle and overlapping symptoms with those of chronic anemia. Its prevalence, as assessed by transthoracic echocardiography, is 30–50% [1, 2] . Together with a high occurrence of thalassemia/hemoglobinopathy [3] , it is likely the most common cause of PAH globally. Thus, acquiring knowledge about its pathogenesis or mechanism of disease seems essential. Compared to sickle cell disease (SCD) patients with functional asplenia, the spleen in thalassemia patients can be very large or can be absent due to therapeutic splenectomy. These different splenic statuses would very likely lead to different mechanisms and managements of PAH in these two groups of patients. Pulmonary artery pressure (PAP) is governed by cardiac output, pulmonary capillary wedge pressure and pulmonary vascular resistance (PVR) [4] . Increased values of these three governing factors, particularly PVR, were shown by right heart catheterization in splenectomized hemoglobin E/β-thalassemia (E/β-Thal) patients [5] . However, until now, there has been no study on the mechanism of the infrequently found mild PAH in nonsplenectomized counterparts [6] . Since clinical and laboReceived: June 4, 2012 Accepted after revision: March 4, 2013 Published online: June 1, 2013

Correction of coagulation and inflammation activation by chronic blood transfusion in an asplenic patient with haemoglobin E/β-thalassaemia and pulmonary arterial hypertension

Dear Sir, Chronic low-grade coagulation and systemic inflammation have been shown to be associated with increased amount of circulating phosphatidylserine-exposing red blood cells (PS-RBCs) in splenectomised haemoglobin E/β-thalassaemia (E/β-Thal) patients (Atichartakarn et al., 2002; Banyatsuppasin et al., 2011), some of whom may also have pulmonary arterial hypertension (PAH) due to thrombotic pulmonary arteriopathy (TPA) (Atichartakarn et al., 2003). Blood transfusion is recommended in the management of this complication (Cogliandro et al., 2008). However, the role of transfusion in modulating the pathophysiology of this condition is poorly described. We gave chronic blood transfusion to a splenectomised E/β-Thal patient with PAH and showed a concomitant reduction in the amount of circulating PS-RBCs, level of plasma thrombin antithrombin complex (TAT), pulmonary vascular resistance and PA pressure (Atichartakarn et al., 2004). The findings suggest that there is a role of PS-RBCs and hypercoagulability in the pathogenesis of TPA-associated PAH. Because of the close relationship between inflammation and coagulation (Esmon, 2003), studying concomitant changes in biomarkers of inflammation could extend our understanding of the hypercoagulable state in these patients. Therefore, sera of this patient were assayed for soluble tumour necrosis factor-α receptors I & II (sTNFR I & II) as sensitive surrogate biomarkers of inflammation (Hanai et al., 2004). Here, we report the findings. All treatment programs and interventions were clearly explained to the patient and signed written consent was obtained. Approval from the Ramathibodi Hospital Institutional Ethics Committee (# 105/1997) was also obtained. Complete blood count; haemoglobin (Hb) typing; serum ferritin; plasma TAT; serology for hepatitis B (HBV), hepatitis C (HCV) and human immunodeficiency virus (HIV) and the amount of PS-RBCs were determined as detailed previously (Atichartakarn et al., 2004). Levels of serum sTNFR I & II were determined by enzyme-linked immunoassay kits (R&D system, Minneapolis, MN) on samples stored at −70 ◦C.