[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.

[CRP and micro-albumin: new markers of cardiovascular risk in type 2 diabetes]. / CRP et micro-albuminurie : nouveaux marqueurs du risque cardiovasculaire chez les diabétiques de type 2.

INTRODUCTION: Type 2 diabetes is a chronic disease associated to the presence of multiple risk factors. Among recently studied factors we cite PCR and micro-albumin. OBJECTIVE: In the present study we intend to determine the correlation between urine albumin excretion rate, CRP levels and type of vascular complications in type 2 diabetes. PATIENTS AND METHODS: We recruited 48 type 2 diabetic subjects subdivided into three groups according to the type of vascular complications (GI: type 2 diabetics without complications, GII: type 2 diabetics with microvascular complications and GIII: type 2 diabetics with macrovascular complications). RESULTS: We found a significant elevated levels of CRP and micro-albumin (P<0.05) when we compared diabetics with vascular complications to those without any complications. Diabetics with macrovascular complications have the highest levels of CRP and micro-albumin. Significant positive correlation was found between CRP and micro-albumin levels in a total group of diabetics (r=0.32; P<0.05). CONCLUSION: The determination of CRP and microalbumin levels represents an interest in the screening of cardiovascular disease in type 2 diabetics.

[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.

NA antigen frequencies in the Tunisian population.

The biallelic NA antigen system is of special interest as the NA antigens are frequent targets of neutrophil antibodies, causing alloimmune neonatal neutropenia, blood transfusion reactions, and chronic benign autoimmune neutropenia in infancy. Neutrophils isolated from the peripheral blood of 119 unrelated individuals at the National Blood Center were phenotyped for NA1 and NA2 using a granulocyte immunofluorescence assay. A subsequent analysis of the phenotyping study showed that the NA1 and NA2 antigen frequencies were 0.529 and 0.865 respectively, and that the estimated NA1 and NA2 gene frequencies were 0.313 and 0.632 respectively. In conclusion, it was determined that the Tunisian population is of Caucasian origin. However, to validate this finding, further investigations are necessary.

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.

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.

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.

Diabetic pregnancy in over 35 years old women.

87 pregnancies in diabetic women older than 35 years at time of conception were studied. 3% were insulin-dependent diabetes mellitus (IDDM), 52% non insulin-dependent diabetes mellitus (NIDDM) and 45% gestational diabetes mellitus (GDM). Mean age was 38 +/- 3 years; BMI was 33.2 +/- 7.0 kg/m2; gestation rate was 5 +/- 3 and number of alive children was 2 +/- 2. Only 3% of pregnancies were planned. Mean time of reference to diabetic care unit was 17 +/- 10 weeks. 95% of the women required human insulin. Mean total daily insulin dose was 0.49 +/- 0.28 UI/kg/d, increasing with gestational age. Mean fasting glycemia was 6.85 +/- 1.93 mmol/l and mean post-prandial glycemia was 8.29 +/- 2.52 mmol/l. Mean time of delivery was 38 +/- 2.1 weeks (less than 37 weeks in 9%). Cesarean section was performed in 44% of 34 cases. Death in utero occurred in 11% of 54 cases, postnatal death in 4%, congenital malformations in 4%, macrosomia in 40%. 9% of infants received intensive neonatal care. No difference was found between NIDDM and GDM about outcome of pregnancy. These results underlined importance of early screening for GDM as most cases seem to be undiagnosed pregravid diabetes mellitus (DM).

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.