Migración del marcapasos como manifestación electrocardiográfica del feocromocitoma / Pacemaker migration as electrocardiographic manifestation of pheochromocytoma

Se describe un caso de feocromocitoma en una paciente remitida a nuestro servicio por cuadro de hipertensión arterial de 3 meses de evolución acompañada de sudoración, cefalea, palpitaciones, pérdida de agudeza visual y alteraciones en el electrocardiograma en forma de alternancia de ondas P positivas con ondas P negativas. Se realiza la anamnesis y la exploración física sospechándose un feocromocitoma, que se confirma con los exámenes complementarios y la intervención quirúrgica, después de la cual desaparece la sintomatología, mejorando las cifras de presión arterial y desapareciendo las alteraciones electrocardiográficas. Este artículo remarca la utilidad del electrocardiograma ante la sospecha clínica de feocromocitoma para orientar nuestras investigaciones diagnósticas hacia la búsqueda del mismo (AU)

Purification of non-toxic, biodegradable arginine-based gemini surfactants, bis(Args), by ion exchange chromatography.

This paper presents an environmentally improved procedure for the preparative purification of a series of arginine-based gemini surfactants. The technique used was cation-exchange chromatography. Mixtures of boric-borate buffer, co-solvent (ethanol), and sodium chloride were tested as eluents. The influence of the buffer pH and the amount of co-solvent on the chromatographic process was studied for the model compound bis(Nalpha-lauroyl-L-arginine) 1,3-propanediamide dihydrochloride, C3(LA)2, and purification conditions were established. The method was scaled-up to the multigram level for C3(LA)2 and the rest of the series. The proposed preparative procedure involves simple equipment, low cost materials, and minimal amounts of solvent (water/ethanol), with low toxicity.

Chemo-enzymatic synthesis of arginine-based gemini surfactants.

A novel chemo-enzymatic synthesis of arginine-based gemini cationic surfactants bis(Args) is reported. These compounds consist of two single N(alpha)-acyl-arginine structures connected through the alfa-carboxylic groups of the arginine residues by a alpha, omega-diaminoalkane spacer chain. N(alpha)-Acyl-L-arginine alkyl ester derivatives were the starting building blocks for the synthesis. The best strategy found consisted of two steps. First, the quantitative acylation of one amino group of the spacer by the carboxylic ester of the N(alpha)-acyl-arginine took place spontaneously, at the melting point of the alpha,omega-diaminoalkane, in a solvent-free system. The second step was the papain-catalyzed reaction between another N(alpha)-acyl-arginine alkyl ester and the free aliphatic amino group of the derivative formed in the first step. Reactions were carried out in solid-to-solid and solution systems using low-toxic potential solvents. Changes in reaction performance and product yield were studied for the following variables: organic solvent, support for enzyme deposition and substrate concentration. The best yields (70%) were achieved in solid-to-solid systems and in ethanol at a(w) = 0.07. Bis(Args) analogs of 8, 10 and 12 carbon atoms using 1,3-diaminopropane and 1, 3-diamino-2-hydroxy-propane as hydrocarbon spacers were prepared at the 6-7 gram level employing the methodology developed. The overall yields which include reaction and purification varied from 51% to 65% of pure (97-98% by HPLC) product.

Qualitative and quantitative analysis of new alkyl amide arginine surfactants by high-performance liquid chromatography and capillary electrophoresis.

A protocol for the qualitative and quantitative analysis of novel arginine-based cationic surfactants using HPLC and CE was studied and compared. The optimization of the analytical conditions was carried out through a systematic variation of the experimental parameters such as mobile phase, eluent conditions, ion pairing and amount of sample for HPLC, and type of buffer, ion strength, type and amount of organic solvent, sample injection time, applied voltage and column washing and conditioning for CE.