Apendicectomía laparoscópica con una sola incisión umbilical (SILS): experiencia en una unidad de cirugía de urgencias / Appendectomy using single-incision laparoscopic surgery: experience in an emergency department

Introduccion: La apendicectomía laparoscópica es un procedimiento ampliamente utilizado en el tratamiento de la apendicitis aguda, que normalmente necesita tres o más trócares para poder llevarse a cabo. Presentamos nuestra experiencia inicial en la apendicectomía por laparoscopia con una sola incisión umbilical (SILS). Método: Estudio prospectivo realizado entre diciembre de 2008 y octubre 2009, en el que los pacientes que aceptaron participar. Fueron operados por cirujanos especialmente dedicados a la patología quirúrgica urgente. El ombligo fue el único punto de entrada en todos los casos y se utilizó la misma técnica quirúrgica en todos ellos. Resultados: Realizamos 52 apendicectomías mediante SILS. La intervención fue realizada con éxito en todos los pacientes: el tiempo operatorio medio fue de 41 min, no se produjo conversión a cirugía abierta ni se necesitó la colocación de otros trócares adicionales y no hubo complicaciones intra ni post operatorias. La estancia media hospitalaria fue de 2,7 días. Conclusión: La apendicectomía en pacientes adultos mediante SILS es una técnica segura, sencilla y fácilmente reproducible (AU)

Background and objective: Laparoscopic appendectomy for acute appendicitis is a widely used procedure. Three ormore trocars are normally required. We present our early experience performing appendectomy by means of singleincision laparoscopic surgery (SILS) for acute appendicitis. Methods: Prospective study from December 2008 to October 2009 in patients who gave their informed consent. Specialists in emergency surgery were responsible for carrying out the procedures. The navel was the point of entry in allcases. Results: We performed 52 emergency laparoscopic appendectomies using a single umbilical incision. The intervention was successful in all patients. The average operating time was 41 minutes. There were no conversions to open surgery or requirement for additional trocars. No complications were observed during or after the procedures. The mean hospital stay was 2.7 days. Conclusion: Adult appendectomy using SILS is a safe procedure that is reproducible and easy to perform (AU)

Solution structure of a DNA duplex with a chiral alkyl phosphonate moiety.

The solution structures of two DNA decamers of sequence d(CCACCpxGGAAC).(GTTCCGGTGG) with a chiral alkyl phosphonate moiety (px) have been determined using NMR and restrained molecular dynamics simulations and compared with the solution structure of the unmodified duplex. The (1)H NMR spectra of two samples with pure stereochemistry in the modified phosphate have been assigned. The structures of both diastereoisomers, as well as the unmodified control duplex, have been determined from NMR-derived distance and torsion angle constraints. Accurate distance constraints were obtained from a complete relaxation matrix analysis of the NOE intensities. The structures have been refined with state of the art molecular dynamics methods, including explicit solvent and applying the particle mesh Ewald method to properly evaluate the long-range electrostatic interactions. In both cases, the calculations converge to well-defined structures, with RMSDs of approximately 1 A. The resulting structures belong to the general B family of DNA structures, even though the presence of the alkyl phosphonate moiety induces some slight displacement to the A-form in the neighborhood of the modified phosphate. Partial neutralization of this phosphate and the steric effect of the alkyl moiety provoke moderate bending in the DNA. This effect is more pronounced in the S diastereoisomer, where the alkyl group points inwards to the double helix.

DNA-triplex stabilizing properties of 8-aminoguanine.

A DNA-triplex stabilizing purine (8-aminoguanine) is designed based on molecular modeling and synthesized. The substitution of guanine by 8-aminoguanine largely stabilizes the triplex both at neutral and acidic pH, as suggested by molecular dynamics and thermodynamic integration calculations, and demonstrated by melting experiments. NMR experiments confirm the triplex-stabilizing properties of 8-aminoguanine and demonstrate that few changes are found in the structure of the triplex due to the presence of this modified base.

Misincorporation of 2'-deoxyoxanosine into DNA: a molecular basis for NO-induced mutagenesis derived from theoretical calculations.

A wide range of theoretical methods, including high level ab initio, density functional, self-consistent reaction field, molecular dynamics and thermodynamic integration calculations, have been used to analyze the mutagenic properties of oxanosine. The major tautomeric forms in the gas phase and aqueous solution have been determined. The ability of oxanosine to recognize thymine and cytosine in the gas phase and in the DNA environment has been compared with that of guanine. A physicochemical explanation for the mutagenic properties of oxanosine is suggested.

Role of sugar re-puckering in the transition of A and B forms of DNA in solution. A molecular dynamics study.

State of the art molecular dynamic simulations show that simple modification of the sugar puckering of 2'deoxyriboses leads to a reversible change between two stable forms of DNA which resemble very closely the canonical A and B duplex forms. Analysis of the A-type and B-type structures reveals interesting, and previously unknown features of these two families of conformations of the DNA.

Can G-C Hoogsteen-wobble pairs contribute to the stability of d(G. C-C) triplexes?

Quantum mechanics, molecular dynamics and statistical mechanics methods are used to analyze the importance of neutral Hoogsteen-wobble G.C pairing in the stabilization of triple helices based on the poly-(G.C-C) trio at neutral pH and low ionic strength. In spite of the existence of a single hydrogen bond, the Hoogsteen-wobble G.C pair is found to be quite stable both in gas phase and solvated DNA. Molecular dynamics simulations of different triplexes based on the d(G.C-C) trio leads to stable structures if the neutral d(G.C-C) steps stabilized by Hoogsteen-wobble pairs are mixed with d(G.C-C+) steps. Finally, high level ab initio calculations and thermodynamic integration techniques are used to determine the relative stability of G.C wobble and G.C imino pairings. It is found that triplexes containing the imino pairing are slightly more stable structures than those with the wobble one, due mainly to a better stacking.

The GAGA factor of Drosophila binds triple-stranded DNA.

The Drosophila GAGA factor binds specifically to simple repeating d(GA.TC)n DNA sequences. These sequences are known to be capable of forming triple-stranded DNA as well as other non-B-DNA conformations. Here, it is shown that GAGA binds to a d[CT(GA.TC)]22 intermolecular triplex with similar specificity and affinity as to a regular double-stranded B-form d(GA.TC)22 sequence. The interaction of GAGA with triplex DNA cannot, however, stimulate transcription in vitro. The affinity of GAGA for triplexes of the purine motif, such as a d[AG(GA.TC)]22 intermolecular triplex, is significantly lower. The DNA binding domain of GAGA is sufficient for efficient binding to triplex DNA. Based on the reported solution structure of the complex of GAGA-DNA binding domain with double-stranded DNA, a model for its interaction with triplex DNA is proposed in which most of the protein-DNA contacts observed in duplex DNA are maintained, especially those occurring through the minor groove. The higher negative charge of the triplex is likely to have also an important contribution to both the specificity and affinity of the interaction.