La docencia en medicina centrada en el estudiante, con publicaciones periódicas / Teaching in the student-centered medicine, with periodicals

La dinámica de grupos permitió que 77 estudiantes del curso regular de Medicina Tropical, efectuaran durante cuatro años, un ensayo sobre la docencia en medicina centrada en el estudiante, mediante la participación en la publicación de artículos médicos en revistas científicas indexadas. Se publicaron 21 artículos: cuatro de investigación clínica, trece de investigación bibliográfica y cuatro de investigación docente con 27 estudiantes que participaron como autores. Se revisaron 823 referencias bibliográficas en la elaboración de los artículos: 20 por ciento de autores venezolanos y 80 por ciento de extranjeros. La ejecución de la experiencia permitió a los estudiantes adquirir destrezas y habilidades en el manejo eficiente de la información bibliográfica, cuando se elaboraron los artículos médicos. Enseñar medicina significa también aprender a publicar la información que va generando la investigación clínica y docente. El propósito fue el de narrar, evaluar y analizar una experiencia docente en la Cátedra de Medicina Tropical

The group dynamics strategy permitted that 77 students from the regular Tropical Medicine course during a four year period, carry out an assay about Teaching Medicine centered on the student, by means of participating and writing medical papers published in indexed medical journals. Twenty one papers were published: four on clinical investigation, thirteen reviews and four on teaching investigation, with 27 students participating as authors. For the publication of the mentioned papers, 823 references were revised: 20 percent corresponded to Venezuelan authors and 80 percent were from other countries. Participating in this experience permitted to the students the practice of capacities and skills related to reference revision applied to writing medical papers. Teaching medicine means also, learning how to publish the data generated during clinical and the teaching practices. The aim was to describe, analyze and evaluate a teaching experience in the Tropical Medicine Department

Evaluation of the transfection property of a peptide ligand for the fibroblast growth factor receptor as part of PEGylated polyethylenimine polyplex.

PURPOSE: Experiments were conducted to evaluate the utility of a peptide receptor ligand to improve transfection efficiency as part of a polyethylenimine-polyethylene glycol (PEI-PEG) polyplex. The 7-mer peptide (MQLPLAT), targeted toward the fibroblast growth factor 2 (FGF2) receptor, was recently identified using a phage-display library method as possessing a high degree of specificity for the FGF2 receptor without the mutagenicity associated with FGF itself. Two approaches (pre-modification or post-modification) to incorporate the peptide into the PEGylated polyplex were compared in terms of their effect on particle size, surface charge, DNA condensation ability, toxicity, cellular uptake and transfection efficiency. METHODS: The peptide was conjugated to branched PEI (25 kDa) via a PEG spacer either before (pre-modified) or after (post-modified) complexation of PEI with DNA. Polyethyleneimine was conjugated to the PEG spacer (N-hydroxy succinimide (NHS) -PEG-maleimide (Mal)) through the NHS group. The FGF2 peptide was synthesized to contain a cysteine at the carboxyl end (MQLPLATC) and conjugated to the PEG spacer via the Maleimide group. Conjugates were evaluated using (1)H NMR, amino acid analysis, and picrylsulfonic acid assay. DNA condensation was evaluated using agarose gel electrophoresis and cellular toxicity was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cellular uptake was measured using flow cytometry and transfection efficiency was determined using a luciferase reporter gene assay. RESULTS: Both pre- and post-modification approaches led to a decrease in the zeta potential of the resulting polyplexes but did not alter their size. The pre-modification of PEI did not affect its ability to condense DNA. However, polyplexes formed with the pre-conjugated PEI did not improve cell uptake or transfection efficiency. In contrast, polyplexes that were post-modified with the FGF2 peptide resulted in a 3-fold increase in cell uptake and a 6-fold increase in transfection efficiency. Both pre- and post-modified polyplexes resulted in lower toxicity compared with unmodified PEI. CONCLUSIONS: The results indicate that the FGF2 peptide improves transfection efficiency when used as part of post-modified PEI/PEG polyplex. When used with pre-modified PEI/PEG, the beneficial effect of the peptide on transfection is not evident, probably because, in this case, the peptide ligand is not readily accessible to the FGF receptor.

Evaluation of two cationic delivery systems for siRNA.

Small interference RNA (siRNA) is an important research tool, and also has the potential for clinical application. RNA interference (RNAi) approaches allow degradation of selective mRNA coding for pathogenic or disease-related proteins. RNAi pathway can be taken advantage of by the delivery of chemically synthesized siRNA. To fully attain its potential a sufficient siRNA must be delivered to the cell's cytoplasm. Cellular delivery of polyanions such as siRNA, while a challenging problem, may be addressed by the use of cationic macromolecules, the two major classes being lipids and polymers. In this study we compared two model cationic vectors liposomes (lipoplexes) and polyethelyenimine (PEI) (polyplexes). Complexes of the cationic macromolecules and siRNA did not differ in terms of their cellular uptake as determined by flow cytometry. However, it was demonstrated that the lipoplexes decomplexed more easily than the polyplexes. Differences in the biological activity of the siRNA were observed using commercially available siTOX siRNA. Lipoplexes resulted in dose-dependent siRNA activity; to 76.4 +/- 5.9% cell death was seen 48 hours posttransfection using 80 nmol siTOX. In summary, the selection of delivery vector can have a profound impact on biological activity of siRNA molecules. siRNA decomplexation from the cationic vector might be an important factor in the future development of new vectors.