[Implication of platelet-activating factor receptor A224D mutation in susceptibility to relapsing-remitting multiple sclerosis: A Tunisian population study]. / Implication de la mutation A224D du récepteur de facteur activateur des plaquettes dans la susceptibilité à la forme rémittente de la sclérose en plaques : étude d'une population tunisienne.

AIM OF THE STUDY: Platelet-activating factor interacts with its specific receptor and mediates leucocytes transmigration into central nervous system and expression of HLA molecules on antigens-presenting cells. These features are the major characteristics of multiple sclerosis pathology. In the present study, we investigated the role of platelet-activating factor receptor A224 mutation in the susceptibility to relapsing-remitting form of MS in a Tunisian population. PATIENTS AND METHODS: Forty-seven multiple sclerosis patients and 72 healthy controls were genotyped for platelet-activating factor receptor A224D mutation using polymerase chain reaction-restriction fragment length polymorphism technique. RESULTS: We used three models of inheritance: the codominant, dominant and recessive models. Our results showed a predisposing effect of platelet-activating factor receptor 224D variant on susceptibility to relapsing-remitting multiple sclerosis (30% vs 48.1%, OR [IC 95%]=2.04 [1.04-3.99], P=0.023). Our results were also consistent with a dominant model of inheritance when comparing mild genotype (AA) with carriers of one or two copies of mutant allele (AD+DD) (55.7% vs 31.9%, OR [IC 95%]=2.92 [1.34-6.81], P=0.006). No effect of this mutation was shown when considering the age at disease onset, disease severity or gender. CONCLUSION: This first study reports an implication of platelet-activating factor receptor A224D mutation in the susceptibility to relapsing-remitting multiple sclerosis in Tunisian population. Further studies will be necessary to confirm the dominant role of PAFR A224D mutation and to elucidate the effect of this mutation on platelet-activating factor/platelet-activating factor receptor pathways.

[Cerebral venous thrombosis: Prospective etiological study of 26 Tunisian patients]. / La thrombose veineuse cérébrale : étude étiologique prospective de 26 patients tunisiens.

PURPOSE: The aim of the present study is to provide a clinical and etiological analysis of cerebral venous thrombosis (CVT) in the Tunisian population. METHODS: This is a prospective monocentric study including 26 patients referred to the Neurology Department of the Military Hospital of Tunis between January 2005 and January 2008. The diagnosis of CVT was confirmed in all patients by magnetic resonance imaging (MRI) and angiography. The clinical and biological risk factors of cerebral venous thrombosis were analyzed. The average follow-up was 18 months (range six to 30). The outcome was assessed clinically with the modified Rankin scale and with MRI. RESULTS: Mean age was 38.26 years, predominantly females (sex-ratio 4.2). The clinical onset was acute in 88.46% of the cases. Headache was the most common inaugural sign (84.6%). Lateral and superior longitudinal sinuses were the most commonly involved with equal frequency (61.53%). Parenchymal lesions were frequently noted (77%), especially hemorrhagic infarcts (46.15%). The causes of CVT were variable and usually combined (85%). Specifically, thrombophilia and obstetric-gynecological causes were predominant with a prevalence of 61.5 and 42.3%, respectively. Septic causes (38.46%) are also frequent, mainly oral infections (27%). Outcome was favorable in 77% of patients given heparin therapy, followed by oral anticoagulants and antibiotics as needed. CONCLUSION: Our Tunisian population presented distinct clinical features compared with previous studies, including a high frequency of thrombophilia and gyneco-obstetrical disorders as well as infectious causes.

[The ABO system polymorphism in Tunisian blood donors]. / Polymorphisme ABO dans une population de donneurs de sang tunisiens.

The present survey was carried out in the Military Center of Blood Transfusion from January 1998 to December 2001. 63,375 blood donors were concerned coming from different regions of Tunisia. Gene frequencies were found as follows: O = 0.686, A = 0.196 and B = 0.120. Important variations are observed between different regions of the country. The comparison with other countries' results traces the history of the Tunisian population, Tunisia being a strategic point in the Mediterranean region.

[Occlusion of the central retinal vein in a 6-month pregnant woman]. / Occlusion du tronc de la veine centrale de la rétine chez une femme enceinte au 6e mois.

The authors report the case of 27-year old woman who was 6 months pregnant (second pregnancy, first parity) and presented an occlusion of the central retinal vein. The etiological investigation revealed impaired fibrinolysis after venous stasis. The clinical course including evolution and therapy was stressed. The role of pregnancy as a supplementary risk factor by haemorrheological mechanism was suggested.

Lack of association between monocyte protein-1 (MCP-1) -2518 A>G chemoattractant and C-C chemokine receptor 2 (CCR2) Val64Ile polymorphisms and multiple sclerosis in a Tunisian population.

Chemokines and their receptors are known to mediate inflammation and tissue damage in autoimmune disorders such as multiple sclerosis (MS). Multiple sclerosis is an inflammatory disease of the central nervous system, characterized by myelin damage and neurological complications. Monocyte chemoattractant protein-1 (MCP-1) interacts with the C-C chemokine receptor 2 (CCR2) and plays a role in the migration of leukocytes into the central nervous system, thus contributing to the T cell-mediated pathogenesis of MS. Genomic DNA obtained from 58 MS patients and 72 healthy controls was tested for the MCP-1 -2518 A>G and CCR2 Val64Ile polymorphisms using polymerase chain reaction-restriction fragment length polymorphism analysis. Neither the MCP-1 -2518G (p=0.43) nor the CCR2 64Ile (p=0.52) variant contributed to the risk of MS in Tunisians.

Abnormalities of coagulation and fibrinolysis in homozygous sickle cell disease.

Abnormalities of coagulation and fibrinolysis were studied in a group of 28 children and young adults with homozygous sickle cell disease (SCD), either in the steady state (n = 12) or during painful crisis (n = 16). Coagulation was explored by standard clotting tests and by measurement of prothrombin complex factors, factor VIII (VIII:C) and antithrombin III (ATIII), protein C (PC) and protein S (PS) activities, while fibrinolytic potential was evaluated using D-dimer, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) assays. In SCD patients, thrombin time (TT) was constantly shortened, both in the steady state (ratio to control 0.83 +/- 0.08, p < 0.0001) and in crisis (0.76 +/- 0.06, p < 0.0001). Mean levels of prothrombin complex were similar in asymptomatic patients to those in controls, but were significantly decreased during sickle cell crisis (p < 0.05 for factor V and p < 0.0001 for factors II, VII and X). Factor VIII:C was significantly increased, both in the steady state (207 +/- 35%, p < 0.0001) and during crisis (208 +/- 34%, p < 0.0001). PS activity was reduced int he steady state (81 +/- 12%, p < 0.01) and further diminished in crisis (68.5 +/- 27.5%, p < 0.001), while D-dimers were significantly elevated during sickle cell crisis (1028 +/- 675 ng/ml, p < 0.001). In all SCD patients, baseline levels of t-PA antigen were comparable to those in controls, whereas concentrations of PAI-1 antigen were significantly increased, either in the steady state (89.7 +/- 26.3 ng/ml, p < 0.0001) or in crisis (75.0 +/- 24.8 ng/ml, p < 0.0001). These results provide evidence for the presence of circulating activated clotting factors in SCD and for an imbalance of the profibrinolytic and antifibrinolytic systems most likely due to increased PAI-1 levels.

Fibrinolytic response to venous occlusion in patients with homozygous sickle cell disease.

The fibrinolytic potential was evaluated in 37 patients with homozygous sickle cell disease and compared to a control group of 30 age- and sex-matched healthy volunteers. In all individuals, the euglobulin clot lysis time and plasma antigen levels of t-Pa and PAI-1 were measured before and after venous occlusion (v.o) for 10 min. The global fibrinolytic activity was normal in 4 patients (good responders to v.o), while it was decreased in 33 patients (poor responders to v.o). Among the latter, 22 patients had significantly increased baseline levels of PAI-1 Ag (82.6 +/- 27.5 ng/ml, p < 0.001) and a normal release of t-Pa Ag after v.o. In contrast, 11 patients had basal values of PAI-1 Ag comparable to those in controls with a defective release of t-Pa Ag after v.o (11.4 +/- 5.2 ng/ml, p < 0.01). These data provide evidence for reduced fibrinolytic capacity resulting from either increased basal levels of PAI-1 or defective release of t-PA.

Antiphospholipid antibodies: lupus anticoagulants, anticardiolipin and antiphospholipid isotypes in patients with sickle cell disease.

Antiphospholipid antibodies were investigated in 37 individuals with sickle cell disease and compared to a control group of 30 healthy subjects. Sickle cell patients included 18 homozygous sickle cell patients, 8 S/beta thalassemic patients and 11 sickle cell trait subjects. In all individuals, antiphospholipid antibodies were explored by lupus anticoagulant (LA) detection and the quantification of IgG and IgM anticardiolipin (aCL) isotypes, total antiphospholipid antibodies (APA) and IgM, IgG and IgA antiphospholipid classes. In homozygous sickle cell patients, mean level of IgG aCL and total APA were significantly increased (17.02 +/- 8.88 GPL/ml, p < 0.05 and 10.64 +/- 10.58 UPL/ml, p < 0.05 respectively). The IgG aCL, total APA and LA frequencies were 22.2%, 44.4% and 62.2%, respectively. APA isotypes were mostly IgG or IgG and IgA. In S/beta thalassemic patients, mean levels of APA were significantly increased (10.81 +/- 7.82 UPL/ml, p< 0.05). Their frequency was 71.4% and they were mostly IgG or IgG and IgA. In patients with sickle cell trait, mean levels of APA were significantly increased (10.84 +/- 5.84 UPL/ml, p < 0.01). Their frequency was 72.7% and mostly of IgG isotype. Our study showed a close association between high APA levels and sickle cell syndrome, however there was no relationship between high levels of antiphospholipid antibodies and the major complications of sickle cell disease.

Anticoagulant profile of iopamidol and meglumine amidotrizoate and their lack of thrombin generation: an in vitro study.

The aim of this in vitro study was to sketch the subtle anticoagulant profile of iopamidol 300 mg l/ml (low osmolality non ionic contrast medium) and meglumine amidotrizoate 370 mg l/ml (high osmolality ionic contrast medium) in situations where variable amounts of clotting factors are observed and to check whether thrombin-generation significantly occurred in non anticoagulated blood-contrast materials mixtures. In the first experiment, mixtures of deficient plasmas with a routine plasma pool provided different ranges with variable amounts of clotting factors II, V, VIII, X, XI and XII. For each clotting factor level studied within these ranges, an activated partial thromboplastin time was determined with either contrast material loaded thromboplastin (5% v/v) or glucose loaded thromboplastin (5% v/v) used as a control. In the second experiment fibrino-peptide A (FpA) or modified antithrombin III (ATM) assays were performed in either (9:1) non anti-coagulated blood contrast materials mixtures or blood-glucose mixtures (control). Differing aPTT prolongation profiles were observed when clotting factors V, VIII, XI and XII were lowered in the plasma. However, neither iopamidol nor amidotrizoate induced an aPTT prolongation with decreasing clotting factor II. In the second experiment no significant thrombin generation was observed as both blood-contrast materials mixtures showed significantly lower FpA and ATM levels (p < 0.001) than glucose control after 5 minutes and 10 minutes incubation at room temperature. These findings provide evidence that the use of iopamidol in angiographic procedures does not increase risk of clotting or hemorrhage.