Situación del cáncer gástrico en el mundo y en Chile

ResumenEl cáncer gástrico es uno de los cánceres más frecuentes en el mundo. Recientes estudios han contribuido en la comprensión de esta enfermedad. El objetivo de este artículo es revisar de manera crítica y actualizada distintos aspectos del cáncer gástrico tanto a nivel mundial como a nivel chileno. Este artículo revisa algunos aspectos relacionados con el cáncer gástrico, tales como epidemiología, dieta, estudio histológico, búsqueda de lesiones precancerosas, prevención, Helicobacter pylori, estilos de vida, factores metabólicos y tratamiento.AbstractGastric cancer is one of the most common cancers in the world. Recent studies have contributed to the understanding of this disease. The aim of this article is to critically review various aspects of gastric cancer both globally and Chilean. This article reviews some aspects related to gastric cancer, such as epidemiology, diet, histology, screening of precancerous lesions, prevention, Helicobacter pylori, lifestyles, metabolic factors and treatment

ENDOSCOPIC ABLATION COMBINED WITH FUNDOPLICATION PLUS ACID SUPPRESSION-DUODENAL DIVERSION PROCEDURE FOR LONG SEGMENT BARRETT´S ESOPHAGUS: EARLY AND LONG-TERM OUTCOME

ABSTRACT BACKGROUND: The addition of endoscopic ablative therapy plus proton pump inhibitors or fundoplication is postulated for the treatment of patients with long-segment Barrett´s esophagus (LSBE); however, it does not avoid acid and bile reflux in these patients. Fundoplication with distal gastrectomy and Roux-en-Y gastrojejunostomy is proposed as an acid suppression-duodenal diversion procedure demonstrating excellent results at long-term follow-up. There are no reports on therapeutic strategy with this combination. AIMS: To determine the early and long-term results observed in LSBE patients with or without low-grade dysplasia who underwent the acid suppression-duodenal diversion procedure combined with endoscopic therapy. METHODS: Prospective study including patients with endoscopic LSBE using the Prague classification for circumferential and maximal lengths and confirmed by histological study. Patients were submitted to argon plasma coagulation (21) or radiofrequency ablation (31). After receiving treatment, they were monitored at early and late follow-up (5–12 years) with endoscopic and histologic evaluation. RESULTS: Few complications (ulcers or strictures) were observed after the procedure. Re-treatment was required in both groups of patients. The reduction in length of metaplastic epithelium was significantly better after radiofrequency ablation compared to argon plasma coagulation (10.95 vs 21.15 mms for circumferential length; and 30.96 vs 44.41 mms for maximal length). Intestinal metaplasia disappeared in a high percentage of patients, and histological long-term results were quite similar in both groups. CONCLUSIONS: Endoscopic procedures combined with fundoplication plus acid suppression with duodenal diversion technique to eliminate metaplastic epithelium of distal esophagus could be considered a good alternative option for LSBE treatment

Model complexity reduction of chemical reaction networks using mixed-integer quadratic programming

The model complexity reduction problem of large chemical reaction networks under isobaric and isothermal conditions is considered. With a given detailed kinetic mechanism and measured data of the key species over a finite time horizon, the complexity reduction is formulated in the form of a mixed-integer quadratic optimization problem where the objective function is derived from the parametric sensitivity matrix. The proposed method sequentially eliminates reactions from the mechanism and simultaneously tunes the remaining parameters until the pre-specified tolerance limit in the species concentration space is reached. The computational efficiency and numerical stability of the optimization are improved by a pre-reduction step followed by suitable scaling and initial conditioning of the Hessian involved. The proposed complexity reduction method is illustrated using three well-known case studies taken from reaction kinetics literature. © 2012 Elsevier Ltd. All rights reserved