Drug Abuse-Induced Cardiac Arrhythmias: Mechanisms and Management

Toxicomania is a worldwide emerging problem threatening young population. Several reports highlighted its hazardous cardiovascular effects. Sudden cardiac death secondary to cardiac arrhythmias is the most occupying issue. Different forms of cardiac rhythm disorders may be induced by illicit drug abuse according to the type of drug and the mechanism involved. In this review, we exposed the main ventricular and supraventricular arrhythmia complicating the common recreational drugs, and we explained their different mechanisms as well as the particularities of management

[Dysfibrinogenemia and thrombosis. A case report].

International audienceBACKGROUND: Congenital dysfibrinogenemia is a functional disorder of the fibrinogen that represents a rare cause of thrombophilia. AIM: To report a Tunisian case of the association dysfibrinogenemia and thrombosis. CASE: A woman with inherited dysfibrinogenemia associated with mild tendency to bleeding experienced a deep vein thrombosis of the lower-extremity at 26 years of age and a fatal pulmonary embolism a few years later. Paradoxically coagulation function of fibrinogen was markedly altered in vitro with a significantly prolonged prothrombin time, activated partial thromboplastin time and thrombin time, a functional fibrinogen level that was undetected and a severely impaired fibrin polymerisation. The thromboembolic events in the patient could be related to dysfibrinogenemia since the main causes of thrombophilia were excluded. CONCLUSION: Although it is rare, this cause of thrombophilia must not be misdiagnosed, systematic measuring of prothrombin time, activated partial thromboplastin time and functional fibrinogen might be helpful

Further characterization and thrombolytic activity in a rat model of a fibrinogenase from Vipera lebetina venom

International audienceVipera lebetina fibrinogenase (VIF) was shown to render fibrinogen incoagulable and to solubilize fibrin. The fibrinogenolytic activity of this enzyme was found to be 33 mg fibrinogen/min/mg protein. The study of the specificity of this enzyme revealed that it has no effect on purified factor X, prothrombin and protein C and on the specific chromogenic substrates of their active form. Plasminogen was not activated by VlF but slightly degraded. We have also compared the effect of VlF and plasmin on fibrinogen and shown that these two enzymes have a different sites of cleavage. This enzyme inhibited human platelet aggregation on PRP initiated by ADP and collagen but was without effect on the aggregation of washed rabbit platelets using thrombin as agonist. Administration of VlF in rat did not show any necrosis or hemorrhage in treated rats organ's. We therefore, examined the thrombolytic activity of VlF in a rat model of venous thrombosis. Thrombus was produced in the posterior vena cava by injection of human fibrinogen and thrombin. Injection of 5 mg/Kg body weight showed an evident flow restoration after one hour and measurement of the fibrinogen level a decrease of about 30% after 3 hrs. VlF's action is not dependent on plasminogen activators and may act synergistically with them, thereby providing an intriguing potential clinical application for dissolution of blood clots

Bleeding and Thrombosis in a Patient with Secondary Antiphospholipid Syndrome

Antiphospholipid antibodies have been associated with occurrence of arterial and venous thrombotic events and fetal loss, which together constitute the antiphospholipid syndrome (APS). However, bleeding is rare in this syndrome. We report a case of systemic lupus erythematosus (SLE) with APS complicated simultaneously by thrombotic and hemorrhagic events. A 34-year-old woman was a known case of diffuse proliferative lupus nephritis associated with APS, on treatment with corticosteroids, cyclophosphamide and anticoagulants. She presented in February 2004 with severe anemia, menorrhagia, gingival bleeding and acute loss of vision in the left eye. Investigations revealed a hematoma in the psoas muscle with thrombosis of the inferior vena cava and occlusion of the retinal vein. Blood tests revealed a strongly positive lupus anticoagulant, factor XI deficiency (35%) and decrease of free protein S (44%). Factor XI inhibitor, anti-prothrombin, and anti-protein S antibodies were absent. The patient was treated with corticosteroids and six pulses of cyclophosphamide, which resulted in a rapid disappearance of bleeding, reduction of hematoma and normalization of hematological abnormalities. She was maintained on corticosteroids, azathioprine and anticoagulant agents were introduced. After a follow-up of 28 months, there was no recurrence of bleeding, the thrombosis had resolved, and there was a decrease in the levels of circulating anticoagulant as well as anticardiolipin antibodies

Amino acid structure and characterization of a heterodimeric disintegrin from Vipera lebetina venom

Referred to by :Ammar Gasmi, Najet Srairi, Sami Guermazi, Hafedh Dekhil, Habib Karoui, Mohamed ElAyebErratum to “Amino acid structure and characterization of a heterodimeric disintegrin from Vipera lebetina venom” [Biochim. Biophys. Acta 1547 (2001) 51–56]Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics, Volume 1764, Issue 9, September 2006, Pages 1525International audienceA heterodimeric disintegrin designed as lebein was isolated from crude Vipera lebetina venom using gel filtration, anion and cation exchange chromatographies on FPLC. The amino acid sequence of each subunit determined by Edman degradation contains 64 residues with ten half-cystines and an RGD site at the C-terminal part of the molecule. The molecular mass of native lebein determined by mass spectrometry was found to be 14 083.4 Da and those of α and β subunits were 6992.05 and 7117.62, respectively. These value are in good agreement with those calculated from the sequences. This protein strongly inhibits ADP induced platelet aggregation on human platelet rich plasma with IC50=160 nM. Sequences of this protein subunits displayed significant sequence similarities with many other monomeric and dimeric disintegrins reported from snake venoms. We identified an amino acid residue (N) in the hairpin loop of both subunits (CRARGDDMNDYC) which is different from all other reported motifs of disintegrins and this subtle difference may contribute to the distinct affinities and selectivities of this class of proteins

Impacts of an uncontrolled phosphogypsum dumpsite on summer distribution of phytoplankton, copepods and ciliates in relation to abiotic variables along the near-shore of the southwestern

International audienceIn connection with the Taparura Project, studies of spatial distribution of the crustacean zooplankton community, nutrients, phytoplankton and ciliates were conducted in July 2007 at 45 stations spread over fifteen transects along the coast north of Sfax. The results showed that the N/P ratio was lower than the Redfield ratio, suggesting potential N limitation. Phytoplankton was characterised by the proliferation of several diatoms, while ciliates were largely dominated by spirotrichs. Copepods were the most abundant zooplankton present during the entire study period, comprising 61% of the total zooplankton community. Twelve copepod families were identified at every station, with a high percentage of Oithonidae (77% of copepods) dominated by Oithona nana. The abundance of this species was correlated with that of diatoms, Cocoolithophorideae and ciliated Colpodea, suggesting that O. nana may feed on a wide range of prey. Despite human pressure and industrial activities, the coastal waters north of Sfax showed a wide diversity of phytoplankton, ciliates and zooplankton

Micro-algal cryopreservation using Dimethyl Sulfoxide (Me2SO) coupled with two freezing protocols: influence on the fatty acid profile

Procedures for determining the optimal pre-freezing protocol for cryo-preservation of microalgae are discussed. Three algal species were used (Chlorella vulgaris, Isochrysis galbana and Dunaliella salina) and cryo-stored using two different methods: the slow cooling and the fast freezing. In the slow cooling, each algae batch was treated with or without cryo-protectant (dimethyl sulfoxide: Me2SO 5% v/v). After 20 min at 4 degrees C, the midi-straws were filled and cooled slowly (1.5 degrees C min(-1)) to -140 degrees C, by a programmable freezer (Digitcool-IMV), before putting them directly into liquid nitrogen. Fast freezing was performed with 10% or 15% Me2SO prior to plunging into liquid nitrogen. The three algal species followed the same re-growth pattern as that of the controls. The post-thawed viability with Me2SO was good for all the selected algae (C. vulgaris > 95%, I. galbana and D. sauna > 70% of the control), applying the slow cooling. The post-thawed viability without Me2SO was 60% for I. galbana, 52% for D. salina and 33% for C. vulgaris. Fast freezing was not suitable for cryo-storage of I. galbana but gave good post-thawing viability for D. salina (70%). The decrease in fatty acid content of the cryo-stored algae was influenced by the temperature. The rapid decrease in temperature induced by fast freezing can explain the low level of fatty acid content of the three cryo-stored algae. Fatty acid profiles show that the nutritional values of the three cryo-stored micro-algae were not significantly affected especially when treated with slow cooling protocols

Microalgal cryopreservation using Dimethyl Sulfoxide (Me2SO) coupled with two freezing protocols : influence on the fatty acid profile

International audienceProcedures for determining the optimal pre-freezing protocol for cryo-preservation of microalgae are discussed. Three algal species were used (Chlorella vulgaris, Isochrysis galbana and Dunaliella salina) and cryo-stored using two different methods: the slow cooling and the fast freezing. In the slow cooling, each algae batch was treated with or without cryo-protectant (dimethyl sulfoxide: Me2SO 5% v/v). After 20 min at 4 degrees C, the midi-straws were filled and cooled slowly (1.5 degrees C min(-1)) to -140 degrees C, by a programmable freezer (Digitcool-IMV), before putting them directly into liquid nitrogen. Fast freezing was performed with 10% or 15% Me2SO prior to plunging into liquid nitrogen. The three algal species followed the same re-growth pattern as that of the controls. The post-thawed viability with Me2SO was good for all the selected algae (C. vulgaris > 95%, I. galbana and D. sauna > 70% of the control), applying the slow cooling. The post-thawed viability without Me2SO was 60% for I. galbana, 52% for D. salina and 33% for C. vulgaris. Fast freezing was not suitable for cryo-storage of I. galbana but gave good post-thawing viability for D. salina (70%). The decrease in fatty acid content of the cryo-stored algae was influenced by the temperature. The rapid decrease in temperature induced by fast freezing can explain the low level of fatty acid content of the three cryo-stored algae. Fatty acid profiles show that the nutritional values of the three cryo-stored micro-algae were not significantly affected especially when treated with slow cooling protocols