Biomedical subjects
Publications and source records attributed to O Hassani.
Performed since the 1950s, vascular grafting has opened modern era of vascular surgery. Autologous venous grafts are of first choice for revascularisation of small arteries. Synthetic grafts are mainly modelled using microporous polytetrafluoroethylene or terephtalate polyethylene. These prosthesis are mainly used for revascularization of medium and large size arteries.
Explore the source record for details and available documents.
We report the case of a surgically treated congenital Budd-Chiari syndrome related to agenesia of the retrohepatic inferior vena cava. The first symptoms of the disease were noticed in childhood. The increasing symptomatology led to propose, at the age of 30 years, first a percutaneous transluminal angioplasty which failed, because of the impossibility to recanalize the obstructed segment. Then a surgical procedure consisting of the implantation of ePTFE prosthesis between the right atria and the retrohepatic inferior vena cava was performed. The hepatic biopsy showed a centrolobular fibrosis and an old subglissonian infarction. The patient was improved, allowing him to recover a normal life. However, three years later, an angiographic evaluation performed because of a recurrence of a slight abdominal pain, showed a thrombosis of the bypass. An attempt at thrombolysis failed. Since the patient did not present major clinical and biological consequences we only proposed a surveillance and no endovascular procedure because of the fear of a pulmonary emboli. The purpose of this case report is to review the literature and discuss the etiopathology of congenital Budd-Chiari syndrome with regard to the different therapeutic options.
Aah VI was isolated from the venom of the North African scorpion, Androctonus australis hector. It is the first glycosylated neurotoxin from scorpion venom to be described. It was not toxic to mice, when injected intracerebroventricularly at a dose of 1.2 microg per animal. However, it had typical activity in Blatella germanica cockroaches resulting in gradual paralysis and very low toxicity (LD50 = 8.5 microg/g of animal). It consists of 66 amino acid residues and is heterogeneously N-glycosylated at a single site, on asparagine 9, of the Asn-Gly-Thr sequence. The potential N-glycosylation site was deduced from automatic Edman degradation and amino acid analysis, and glycan heterogeneity was evidenced by ESMS. Determination of the N-glycan structures (dHex, Hex and HexNAc) was assessed by nanoESMS/MS with picomolar amounts of sample. Current knowledge of N-glycan structure and composition suggests that the glycan structures are derived from a common core.
Toxin VII (TsVII), also known as Ts gamma, is the most potent neurotoxin in the venom of the Brazilian scorpion Tityus serrulatus. It has been purified to homogeneity using a new fast and efficient method. Chemical modification of TsVII with the tryptophan-specific reagent o-nitrophenylsulfenyl chloride yielded three modified derivatives (residues Trp39, Trp50 and Trp54). Acetylation of TsVII mostly generated the monoacetylated Lys12 derivative. No side reactions were detected, as indicated by endoproteinase Lys-C peptide mapping, Edman degradation and electrospray mass spectrometry. Circular dichroism and fluorimetric measurements showed that none of the chemical modifications altered the overall structure of the derivatives. The acetylation of Lys12 or the sulfenylation of Trp39 or Trp54 led to a loss of both toxicity in mice and apparent binding affinity for rat brain and cockroach synaptosomal preparations. Sulfenylation of Trp50, however, moderately affected the toxicity of TsVII in mice and had almost no effect on its binding properties. A 3-dimensional model of TsVII was constructed by homology modeling. It suggests that the most reactive residues (Lys12 and Trp39 and Trp54) are all important in the functional disruption of neuronal sodium channels by TsVII, and are close to each other in the hydrophobic conserved region.
We report the case of an 84 year-old man who suffered of paraplegia after surgery of an abdominal aortic aneurysm. The neurologic status did not improve during 5 years of follow-up. This complication is rare in light of the review of the literature. It is more frequent after emergency (1.4%) and redux (19%) surgery than after elective surgery (1.1%). Its mechanisms are anatomic (occlusion of the Adamkievitz artery and of the pelvic collateral arteries) and hemodynamic mechanisms (thromboembolism, low systemic tension, long supra-renal clamping). Since pre-operative aortography to detect anatomic variations is not realistic, its only prevention remains maintenance of intra-operative hemodynamic, systemic heparinization, and preservation of the pelvic collateral circulation.
The venom of the scorpion Androctonus australis hector contains several protein neurotoxins of which structure and structure/activity relationships have been extensively studied. It also contains polypeptides such as Aah STR1, which are not toxic, while having highly similar sequences to fully active toxins. We have determined the solution structure of Aah STR1 by use of conventional two-dimensional NMR techniques followed by distance-geometry and energy minimization. We have demonstrated that, despite its lack of toxicity, Aah STR1 is structurally highly related to anti-mammal scorpion toxins specific for Na+ channels. The calculated structure is composed of a short alpha-helix (residues 26-33) connected by a tight turn to a three-stranded antiparallel beta-sheet (sequences 3-6, 38-41 and 44-48). This beta-sheet is right-handed twisted as usual for such secondary structures. The beta-turn connecting the strands 38-41 and 44-48 belongs to type II'. The overall fold of Aah STR1 is typical of beta-type scorpion toxins. This is, however, the first example of such a fold in Old World scorpion toxins. Either the absence of a basic residue in position 63 or the high mobility of loops, compared to active beta-type neurotoxins, may explain the lack of activity of this protein.
Endarterectomy of the carotid bifurcation through a longitudinal arteriotomy of the common and internal carotid arteries followed by a direct closure is still accepted as the main surgical technique for carotid stenoses. However, this technique is complicated in about 10% of the cases by a restenosis. Mechanisms of myointimal hyperplasia leading to restenosis are not completely explained. The technique of eversion endarterectomy of the internal carotid artery has been said to be an alternate technique which could decrease the incidence of restenosis. We described the three main techniques of eversion endarterectomy and their results. The technique of eversion endarterectomy after proximal section of the internal carotid artery is the most frequently used. It allows to treat easily length excess of the internal carotid artery. Its results are good in terms of neurologic morbidity and mortality. However, randomized comparative studies are still required in order to determine its role on the incidence of restenosis despite the first encouraging results of first non comparative studies. The technique of eversion endarterectomy after distal section of the internal carotid artery has been proposed by Chevalier who reported also good short term results and no delayed restenosis.