Exploring genomic structure differences and similarities between the Greek and European HapMap populations: implications for association studies.

Studies of the genomic structure of the Greek population and Southeastern Europe are limited, despite the central position of the area as a gateway for human migrations into Europe. HapMap has provided a unique tool for the analysis of human genetic variation. Europe is represented by the CEU (Northwestern Europe) and the TSI populations (Tuscan Italians from Southern Europe), which serve as reference for the design of genetic association studies. Furthermore, genetic association findings are often transferred to unstudied populations. Although initial studies support the fact that the CEU can, in general, be used as reference for the selection of tagging SNPs in European populations, this has not been extensively studied across Europe. We set out to explore the genomic structure of the Greek population (56 individuals) and compare it to the HapMap TSI and CEU populations. We studied 1112 SNPs (27 regions, 13 chromosomes). Although the HapMap European populations are, in general, a good reference for the Greek population, regions of population differentiation do exist and results should not be light-heartedly generalized. We conclude that, perhaps due to the individual evolutionary history of each genomic region, geographic proximity is not always a perfect guide for selecting a reference population for an unstudied population.

Phenotype and genotype frequency of ß-thalassemia and sickle cell disease carriers in Halkidiki, Northern Greece.

A decade of screening (years 2000 to 2010) for hemoglobinopathies in 3,931 patients was performed at the General Hospital of Poligiros, Halkidiki, Northern Greece. Among the patients examined, 10.8% heterozygotes for ß-thalassemia (ß-thal) were found, as well as 4.1% with sickle cell disease and 1.2% with double ß-thal/Hb S [ß6(A3)Glu→Val] heterozygosity. Iron deficiency was observed in 23.4%. The geographical distribution in the region revealed a substantial incidence of hemoglobinopathies even in mountainous areas. This pattern did not follow the typical distribution according to the malaria hypothesis, as incidence did not dovetail with swamp locations recorded in the past. The HBB gene mutations for 85 patients were also analyzed. Most prevalent in Halkidiki, Northern Greece, was the codon 39 (C>T) mutation (27.1%) followed by the IVS-I-110 (G>A) mutation (22.4%); this was in direct contrast to the current distribution of the same mutations seen in the rest of Greece (Greek National Genetic Database, GNGD). This frequency inversion was statistically significant, with the difference from the GNGD being 20.6% for the IVS-I-110 mutation (p <0.0005) and 7.6% for the codon 39 mutation (p = 0.0238). The history of Halkidiki, denoting a clear example of geographical isolation from the rest of the country, may possibly account for a potentially diverse genetical identity of the disease in this region.

Pregnancy in beta-thalassemia trait carriers: an uneventful journey.

Normochromic normocytic anemia during pregnancy reflects the significant increase in plasma volume, which disproportionately exceeds the increase in the red cell volume. In beta-thalassemia (beta-thal) trait carriers who become pregnant the plasma volume expansion may cause more pronounced anemia because the anemia of pregnancy is added to the pre-existed hypochromic microcytic anemia. In beta-thal women, pregnancy outcome and obstetric complications do not differ from the general population. Anemia in beta-thal carriers is generally not severe enough to warrant anxiety. No specific therapy is indicated and pregnant women generally require only supportive care with an anticipated favorable pregnancy outcome.

Effect of HbS in the determination of HbA2 with the Biorad Variant II analyzer.

OBJECTIVES: The effect of the presence of HbS in the determination of HbA2 using the Biorad Variant II analyzer. DESIGN AND METHODS: The effect of HbS presence in the samples was quantified using the HELENA SAS-MX alkaline gel electrophoresis kit as the reference method. RESULTS: The %HbA2 values from the Variant II analyzer and the HELENA SAS-MX alkaline gel electrophoresis kit show a good linear correlation in the absence of HbS. A strong positive bias in the %HbA2 values from the Variant II is apparent in the presence of HbS in the samples, when compared to the alkaline electrophoresis gel. CONCLUSION: The Variant II analyzer gives reliable results for %HbA2 determination when no HbS is detectable in the samples. When HbS is present, the gel electrophoresis method gives more accurate results.

Leukocyte activation after coronary stenting in patients during the subacute phase of a previous ST-elevation myocardial infarction.

OBJECTIVE: To study leukocyte activation after percutaneous coronary intervention in patients with previous ST elevation myocardial infarction. METHODS: Neutrophil and monocyte activation (by flow cytometric assessment of the surface expression of CD11b and CD62L adhesion molecules) was assessed in 39 patients during the subacute period of a previous ST elevation myocardial infarction initially treated with fibrinolytic agents, before and after diagnostic coronary angiography (coronary angiography control phase) as well as before and after stent implantation (percutaneous coronary intervention phase). Simultaneous evaluation of C-reactive protein (C-reactive protein immonoturbidimetry) and plasma cytokine levels (interleukins-1, -6, -10 and tumor necrosis alpha by immunoassay) was also performed. To track the earliest detectable change in the first few minutes after stent deployment, all measurements were performed before and 60 min after the procedures. RESULTS: CD11b expression increased 1 h after stent deployment in neutrophils (P<0.0001) and monocytes (P<0.0001). A comparable increase, however, was also observed after coronary angiography (neutrophils, P=0.03; monocytes, P=0.01), although the increase of CD11b expression was greater after percutaneous coronary intervention on both neutrophils (90 vs. 40%, P=0.014) and monocytes (65 vs. 33%, P=0.04). CD62L expression decreased significantly after percutaneous coronary intervention (neutrophils, P=0.01; monocytes, P=0.006), but remained unchanged after coronary angiography. Plasma cytokine and C-reactive protein concentrations did not change after the procedures. CONCLUSION: CD62L appears to be a specific and reliable early cellular biomarker of leukocyte activation after percutaneous coronary intervention, when this procedure is performed in patients with previous ST elevation myocardial infarction. Whether this marker represents also a potential predictor of future events and/or restenosis in this group of patients remains to be defined.

Effect of HbS in the determination of HbA(2) with the TOSOH HLC-723G7 analyzer and the HELENA Beta-Thal Quik column kit.

OBJECTIVES: The analytical performance of the TOSOH HLC-723G7 hemoglobin HPLC analyzer and the effect of the presence of HbS in the determination of HbA(2) using HPLC and manual column methods. DESIGN AND METHODS: The performance characteristics of the TOSOH HLC-723G7 analyzer in the determination of HbA(2) were compared to those of the HELENA Beta-Thal Quik column. The effect of HbS presence in the samples was quantified using the HELENA SAS-MX alkaline gel electrophoresis kit as the reference method. RESULTS: Within-run and between-run CVs for HbA(2) were better for the TOSOH HPLC analyzer than for the HELENA manual column method. The presence of HbS in the samples produces a strong positive bias in the %HbA(2) values when using both the HPLC and manual column methods, compared to the alkaline electrophoresis gel. CONCLUSION: Both the TOSOH HPLC and the manual column are reliable methods for %HbA(2) determination when no HbS is detectable in the samples. When HbS is present, the gel electrophoresis method gives more accurate results.

Clotting state after cardioversion of atrial fibrillation: a haemostasis index could detect the relationship with the arrhythmia duration.

BACKGROUND: Fibrin D-dimer levels have been advocated as an useful clinical marker of thrombogenesis. HYPOTHESIS: We hypothesized that i) there is a hyperclotting state after the return of atrial fibrillation to sinus rhythm, ii) the measurement of plasma D-Dimer levels might be a good screening tool of this clotting status, and iii) the duration of arrhythmia influences the haemostasis measured by plasma D-Dimer levels. METHODS: Forty-two patients with atrial fibrillation undergoing cardioversion were divided into two groups: in Group A (n = 24,14 male, 56 +/- 11 years) the duration of atrial fibrillation was 72 hours or more (142.7 +/- 103.8 hours), in Group B (n = 18, 10 male, 61 +/- 13 years) the duration of atrial fibrillation was less than 72 hours (25 +/- 16 hours). Plasma fibrin D-dimer levels were measured by enzyme immunoassay before, and 36 hours after, cardioversion. The change of plasma D-dimer levels 36 hours after cardioversion was calculated as delta-D-dimer. RESULTS: There were no significant differences in demographic, clinical, and echocardiographic data, and the success of cardioversion between the two groups. Compared to the control, the baseline D-dimer levels were significantly higher in both groups. The delta D-dimer levels were significantly higher in Group A than in Group B (p < 0.005). Furthermore, plasma D-dimer levels 36 hours after cardioversion (r = 0.52, p = 0.0016) and delta-D-dimer levels (r = 0.73, p < 0.0001) showed significant correlations with the duration of atrial fibrillation. CONCLUSION: The longer duration of the atrial fibrillation episode could lead to a more prominent cardiovascular hyperclotting state after cardioversion, and the mean changes of plasma D-Dimer levels could be used as an useful clinical marker of the clotting state after atrial systole return.

Assessment of platelet adhesiveness and aggregation in mild acute pancreatitis using the PFA-100 system.

CONTEXT: Acute pancreatitis constitutes a systemic inflammatory process which is often accompanied by thrombosis and bleeding disorders. The role of platelets in the pathophysiology of the disease remains to be elucidated. OBJECTIVE: In the present study, we evaluated the alterations of platelet function in patients suffering from acute edematous pancreatitis using the recently developed platelet function analyzer PFA-100. DESIGN: A cohort study with one end-point (difference between patients with acute edematous pancreatitis and normal controls concerning at least one PFA-100 closure time at the P<0.01 level of statistical significance). MAIN OUTCOME MEASURE: The hemostatic capacity of platelets was tested in citrated blood and standard cartridges containing collagen-ADP or collagen-epinephrine. PATIENTS: We studied 16 patients (6 women and 10 men, mean age 62.1 years) with acute edematous pancreatitis, who had been admitted to our Internal Medicine Department, along with 32 normal controls of similar age and having the same woman-man ratio. RESULTS: The mean closure time using collagen-ADP cartridges was 69.6 s (95% CI: 60.4-78.7 s) in patients and 96.1 s (95% CI: 93.0-99.3 s) in normal controls (t-value: 7.2; P<0.001). The mean closure time using collagen-epinephrine cartridges was 110.7 s (95% CI: 100.1-121.3 s) in patients and 119.7 s (95% CI: 114.6-124.8 s) in normal controls (t-value: 1.8; P=0.078). The hematocrit in all patients was less than the upper reference value. CONCLUSIONS: The PFA-100 represents a simple and easy to use test for investigating primary hemostasis. Although the method has been widely used in hemorrhagic conditions, this is the first time it has been applied in the prethrombotic model of acute pancreatitis, suggesting increased platelet adhesiveness and aggregation.

Atrial fibrillation and hypercoagulability: dependent on clinical factors or/and on genetic alterations?

UNLABELLED: It is well known that atrial fibrillation is associated with high incidence of thromboembolic events, propably due to a prothrombotic or hypercoagulable state. However, it is unclear whether or not there is any difference of this prothrombotic state in the clinical subgroups of atrial fibrillation patients, that is, in those with paroxysmal, persistent or permanent atrial fibrillation. From the other side the role of the arrhythmia duration on the changes of coagulative variables in atrial fibrillation patients is not clearly enough. The contribution of genetic and functional alterations in factors of the coagulation and fibrinolytic pathways (that is hemostatic risk factors) to the development of hypercoagulation state in atrial fibrillation requires clarification. We investigated therefore (1) if there are differences in the prothrombotic state between patients with different clinical status of the arrhythmia, (2) if the arrhythmia duration per se could be an independent determinant of the prothrombotic state in all atrial fibrillation patients and (3) if coexistent genetic alterations in haemostatic risk factors in patients with atrial fibrillation could contribute to the development of prothrombotic abnormalities. METHODS: Over a period of 23 months, we studied 55 patients with chronic non-valvular atrial fibrillation. We recruited 18 consecutive patients (13 men, mean age 59 +/- 10 years) with paroxysmal atrial fibrillation 17 patients (11 men, mean age 61 +/- 7 years) with persistent atrial fibrillation who underwent elective successful DC and remained in sinus rhythm at the 3 month visit and 20 patients (14 men mean age 64 +/- 9) with permanent atrial fibrillation. Blood results were compared to 17 age-sex- and race-matched controls. The prothrombotic state was quantified by measurement of plasma levels of fibrinogen, soluble P -selectin (an index of platelet activation) and von Willebrand factor (a marker of endothelial dysfunction). We assessed the frequencies of factor V Leiden and prothrombin variant G20210A to determine whether particular inherited haemostatic risk factors may have contribution to the development of prothrombotic state in atrial fibrillation patients. RESULTS: Permanent atrial fibrillation was associated with significant raised levels of von Willebrand factor, fibrinogen levels and soluble P -selectin compared to matched controls (all p < 0.001) and matched patients with paroxysmal and permanent AF (all p ranged between <0.003 and <0.002). Patients with persistent atrial fibrillation had significantly elevated von Willebrand factor levels (p = 0.0064) and fibrinogen levels (p = 0.002), but not Soluble P -selectin (p = 0.509). when compared to controls. Patients with paroxysmal atrial fibrillation had significantly elevated levels of P -selectin (p = 0.005) and fibrinogen (p = 0.003), but not von Willebrand factor (p =.0.61) compared to controls. Stepwise multiple regression analyses demonstrated that the arrhythmia duration (approximately 3 years) was an independent predictor of abnormal von Willebrand factor, fibrinogen and soluble P -selectin levels. Restoration of sinus rhythm in paroxysmal atrial fibrillation subgroup and successful electrical cardioversion of patients with permanent fibrillation atrial fibrillation did not significantly alter levels of the affected factors. The frequency of factor V Leiden was 8.9 in all studied patients with atrial fibrillation, versus 2.4% in the control group (odds ratio [OR] 4.6 [95% confidence (CI) 1.4-17.5], p = 0.02). The frequency of the prothrombin variant G20210A was 6.4.% compared with control group 1.6% (OR 4.9 [95% confidence interval (CI) 1.2-2.9], p = 0.04). There was a trend towards an increased frequency of factor V Leiden and/or prothrombin variant G20210A in patients age <55 years and in patients living at a particular area of Thrace mountains. CONCLUSIONS: Our results showed that there were significant differences in the prothrombotic state when patients with paroxysmal, and persistent atrial fibrillation were compared to matched that there were significant differences in the prothrombotic state when patients with paroxysmal, and persistent atrial fibrillation were compared to matched patients with permanent atrial fibrillation and controls in sinus rhythm. The duration of the arrhythmia (about 3 years) was an independent predictor of abnormal measured factors. We found for the first time that some genetic alterations in haemostatic risk factors could be coexist in atrial fibrillation patients and may be a contributor to the development of hypercoagulability in atrial fibrillation patients.