[Periprocedural management of anticoagulation in patients undergoing atrial fibrillation ablation]. / Anticoagulation péri-interventionnelle lors d'ablation de fibrillation auriculaire.

Catheter ablation of atrial fibrillation (AF) has been increasingly performed and has become a standard of care treatment option for drug-refractory symptomatic patients. However, this procedure has been associated with major complications, like thromboembolic or bleeding events. Optimal periprocedural anticoagulation strategy is essential for minimizing these complications. In this article, we review current anticoagulation strategies, including use of oral anticoagulation with Vit-K-Antagonists, as well as use of direct oral anticoagulants in the periprocedural settings of AF ablation.

Histone acetylation and disease.

Differential acetylation of histones and transcription factors plays an important regulatory role in developmental processes, proliferation and differentiation. Aberrant acetylation or deacetylation leads to such diverse disorders as leukemia, epithelial cancers, fragile X syndrome and Rubinstein-Taybi syndrome. The various groups of histone acetyltransferases (CBP/p300, GNAT, MYST, nuclear receptor coactivators and TAFII250) and histone deacetylases are surveyed with regard to their possible or known involvement in cancer progression and human developmental disorders. Current treatment strategies are discussed, which are still mostly limited to histone deacetylase inhibitors such as trichostatin A and butyrate.

Characterization of CELO virus proteins that modulate the pRb/E2F pathway.

The avian adenovirus CELO can, like the human adenoviruses, transform several mammalian cell types, yet it lacks sequence homology with the transforming, early regions of human adenoviruses. In an attempt to identify how CELO virus activates the E2F-dependent gene expression important for S phase in the host cell, we have identified two CELO virus open reading frames that cooperate in activating an E2F-inducible reporter system. The encoded proteins, GAM-1 and Orf22, were both found to interact with the retinoblastoma protein (pRb), with Orf22 binding to the pocket domain of pRb, similar to other DNA tumor virus proteins, and GAM-1 interacting with pRb regions outside the pocket domain. The motif in Orf22 responsible for the pRb interaction is essential for Orf22-mediated E2F activation, yet it is remarkably unlike the E1A LxCxD and may represent a novel form of pRb-binding peptide.

Efficient gene delivery into human dendritic cells by adenovirus polyethylenimine and mannose polyethylenimine transfection.

Gene-modified human dendritic cells (DCs) were generated by transfection with adenovirus polyethylenimine DNA (Ad/PEI/DNA) and mannose polyethylenimine DNA (ManPEI/DNA) complexes. Ad/PEI/DNA complexes have plasmid DNA bound to adenovirus particles by PEI and deliver DNA into cells via the adenovirus infection route. Such transfection complexes yield high transduction levels and sustained expression of luciferase and green fluorescent protein reporter genes and were almost as effective as recombinant adenovirus vectors. ManPEI/DNA complexes rely on uptake by receptor-mediated endocytosis via mannose receptor, which is highly expressed on DCs. While gene delivery by ManPEI/DNA complexes was less efficient than by Ad/PEI transfection, incorporation of adenovirus particles in ManPEI/DNA transfection complexes further enhanced transduction efficiencies and transgene expression. We also demonstrate that Ad/PEI-transfected DCs are competent in stimulating T cell proliferation in allogeneic and autologous mixed lymphocyte reactions, and in activating T cells from T cell receptor (TCR)-transgenic mice in an antigen-specific manner. Thus, the present study establishes the following relative order of transduction efficiencies of viral and nonviral gene delivery systems for primary human DCs: recombinant adenovirus > Ad/PEI = Ad/ManPEI > ManPEI > PEI. Ad/PEI and ManPEI transfection modes represent particularly versatile transduction systems for DCs, with ManPEI being built up exclusively of synthetic compounds.

Mutational analysis of the avian adenovirus CELO, which provides a basis for gene delivery vectors.

The avian adenovirus CELO is being developed as a gene transfer tool. Using homologous recombination in Escherichia coli, the CELO genome was screened for regions that could be deleted and would tolerate the insertion of a marker gene (luciferase or enhanced green fluorescent protein). For each mutant genome, the production of viable virus able to deliver the transgene to target cells was monitored. A series of mutants in the genome identified a set of open reading frames that could be deleted but which must be supplied in trans for virus replication. A region of the genome which is dispensable for viral replication and allows the insertion of an expression cassette was identified and a vector based on this mutation was evaluated as a gene delivery reagent. Transduction of avian cells occurs at 10- to 100-fold greater efficiency (per virus particle) than with an adenovirus type 5 (Ad5)-based vector carrying the same expression cassette. Most important for gene transfer applications, the CELO vector transduced mammalian cells as efficiently as an Ad5 vector. The CELO vector is exceptionally stable, can be grown inexpensively in chicken embryos, and provides a useful alternative to Ad5-based vectors.

Polyethylenimine (PEI) is a simple, inexpensive and effective reagent for condensing and linking plasmid DNA to adenovirus for gene delivery.

A simple and inexpensive method of condensing and linking plasmid DNA to carrier adenovirus particles is described. The synthetic polycation polyethylenimine is used to condense plasmid DNA into positively charged 100 nm complexes. These PEI-DNA complexes are then bound to adenovirus particles through charge interactions with negative domains on the viral hexon. The resulting transfection complexes deliver plasmid DNA to cells by the adenovirus infectious route without interference from virus gene expression because psoralen-inactivated virus is employed. The PEI-DNA-adenovirus complexes display DNA delivery comparable to more sophisticated DNA virus complexes employing streptavidin/biotin linkage, but require no special reagents and are much easier to prepare.

Stabilization of gene delivery systems by freeze-drying.

Freeze-drying of three different forms of gene delivery systems was performed using a controlled two-step drying process and 10% sucrose as lyoprotectant. Complexes of pCMVL plasmid with transferrin-conjugated polyethylenimine, adenovirus-enhanced transferrinfection consisting of pCMVL/transferrin-polylysine complexes linked to inactivated adenovirus particles, and a recombinant, E1-defective adenovirus expressing a luciferase reporter gene were tested. Three weeks after freeze-drying the reagents were rehydrated with water and tested for transfection activity. Luciferase gene expression levels were retained at high levels in all three systems, in contrast to reagents stored in solution. The use of the lyoprotectant was essential. In the absence of sucrose the transfection activities dropped by a factor of 100-1000. The data suggest freeze-drying as a useful method for stabilization and storage of standardized batches of transfection agents.