[Percutaneous mitral commissurotomy and Lutembacher syndrome]. / Commissurotomie mitrale percutanée et syndrome de Lutembacher.

INTRODUCTION: Lutembacher syndrome refers to the rare combination of congenital atrial septal defect and acquired mitral stenosis. This condition is usually treated surgically by mitral valve operation with concomitant closure of the atrial septal defect. MATERIALS AND METHODS: Between 1993 and 2003, 4 patients with congenital Lutembacher syndrome had percutaneous mitral commissurotomy without closure of the atrial septal defect at our institution. The 4 patients were very symptomatic with right-sided heart failure signs and NYHA functional class III-IV. RESULTS: The procedure was carried out successfully for the four patients. Mitral valve area increased from 0.87 to 1.97 cm2 at mean; left atrial pressure decreased from 28.2 to 12.7 mmHg and the mean valve mitral gradient was reduced from 15.5 to 3.9 mmHg. Functional and clinical improvement was observed in all the cases. During a mean follow up of 55 +/- 29 months, our 4 patients remain pauci symptomatic under medical treatment. CONCLUSION: The percutaneous treatment of the Lutembacher syndrome is currently a possible alternative to the surgery among patients having an anatomy favourable to the procedure.

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

A 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 14083.4 Da and those of alpha and beta 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 IC(50)=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 (CNRARGDDMNDYC) 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.

Lebecetin, a C-lectin protein from the venom of Macrovipera lebetina that inhibits platelet aggregation and adhesion of cancerous cells.

A novel C-lectin protein, lebecetin, was purified and characterized from the venom of Macrovipera lebetina. It is a disulfide-linked heterodimer of 15 and 16 kD. The subunits are homologous to each other and to the other snake venom proteins of the C-type (Ca(2+)-dependent) lectin superfamily. Lebecetin shows a potent inhibitory effect on whole blood and washed platelets induced by different agonists. It inhibits the agglutination of human fixed platelets in the presence of ristocetin. Lebecetin also interferes with the adhesion of IGR39 melanoma and HT29D4 adenocarcinoma cells. These two lines adhere to lebecetin used as matrix. Lebecetin is also able to strongly reduce IGR39 and HT29D4 cell adhesion to fibrinogen and laminin, but not to fibronectin and collagen types I and IV, respectively. Adhesion properties of lebecetin may thus involve integrin receptors.

Amino acid sequence of VlF: identification in the C-terminal domain of residues common to non-hemorrhagic metalloproteinases from snake venoms.

The complete amino acid sequence of a non-hemorrhagic fibrino(geno)lytic enzyme (VlF) isolated from Vipera lebetina venom has been determined. VlF was subjected to separate enzymatic and chemical digestions. Resulting fragments were purified by RP-HPLC and subjected for sequencing by automated Edman degradation. The amino terminus of VlF was determined by mass spectrometry. VlF was shown to be composed of 202 residues having a relative molecular mass of 22,826 Da and containing a zinc-binding site and a catalytically active residue. It displayed significant sequence similarities with many other mature metalloproteinases reported from snake venoms. Sequence comparison of hemorrhagic and non-hemorrhagic mature metalloproteinases revealed the presence at the C-terminal part of the enzymes of two residues common to only hemorrhagic metalloproteinases and two others shared by only non-hemorrhagic ones.

Purification and characterization of a growth factor-like which increases capillary permeability from Vipera lebetina venom.

We have investigated the effect of Vipera lebetina venom on capillary permeability and isolated an increasing capillary permeability protein (ICPP) which is devoid of arginine ester hydrolase and phospholipase A2 activities. This protein was purified with a yield of about 0.2% by fast protein liquid chromatography (FPLC) using successively Superose 12, Mono Q, and Mono S columns and by high-pressure liquid chromatography (HPLC) on a C8 reverse-phase column. The purified protein migrated on SDS-PAGE as a band of about 27 kDa under nonreducing conditions and as a band of about 16 kDa under reducing conditions. Chromatography on a C8 column of reduced and alkylated protein yielded a single peak suggesting that this protein is homodimeric. This protein was refractory to Edman degradation chemistry. We used successfully a chemical unblocking involving the incubation of the protein with HCl in anhydrous methanol. The N-terminal amino acid sequence clearly shows considerable similarity to that of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF).

The development and evolution of actin-containing organelles during spermiogenesis of a primitive nematode.

Spermatogenesis in the primitive marine nematode Sphaerolaimus hirsutus (Chromadoria, Sphaerolaimidae) was investigated by examining the ultrastructure and cytochemistry. Spermatozoa are lenticular cells of about 15 microns in diameter and are devoid of flagellum and acrosome as in other nematodes. In spermatocytes, dictyosomes produced transient structures, the fibrous body-membranous organelle complexes (FB-MO). In spermatids, the FBs were arranged as cartwheel spokes, with the FBs in the centre and the MOs at the periphery. The FBs were first made up of parallel fibres and surrounded by a membrane, then, in a later stage, showed a dense central structure with a surrounding vermiculate region and were devoid of membrane. The FBs contain actin as shown by immunofluorescence using a monoclonal anti-actin antibody and by affinity cytochemistry using fluorescent phalloidin. MOs contained mainly F-actin as shown by their labelling by phalloidin. In spermatozoa, the MOs were no longer peripheral but arranged on a ring in the central region of the cell and the FBs disappeared to form the cytoskeleton of the cell outer region. It was assumed, by analogy with the ultrastructure of other nematodes, that this cytoskeleton was made up of major-sperm-protein (MSP). Labelling of spermatids of Caenorhabditis elegans also revealed the presence of actin, but cells and actin spots were very small. This demonstrates the interest of Sphaerolaimus as a giant sperm model in which fibrous bodies and membranous organelles can be distinguished. In the few species in which it has been studied (C elegans and Ascaris suum), MSP is thought to constitute in spermatozoa a motile cytoskeleton excluding the presence of actin. However, the present study of Sphaerolaimus shows that the actin cytoskeleton is present during nematode spermiogenesis.