Surface-enhanced Raman scattering of picolinamide, nicotinamide, and isonicotinamide: unusual carboxamide deprotonation under adsorption on silver nanoparticles.

Surface-Enhanced Raman Scattering (SERS) of picolinamide, nicotinamide, and isonicotinamide has been studied on silver colloids at pH⩾7. The wavenumbers of the SERS bands assigned to 1; νring and ν(C-X) vibrational modes show important blue-shifts (ca. +50cm(-1)) with respect to the Raman spectra, whereas the Amide III bands undergo red-shifts up to -50cm(-1). We demonstrate that these shifts are originated by the deprotonation of the carboxamide groups which link to the metal through the nitrogen and oxygen atoms of the respective azanion groups. In order to support this conclusion, theoretical DFT force field calculations have been carried out, confirming that the pyridinecarboxamides interact with the metallic surface in their deprotonated forms as benzamide does.

Evidence of deprotonation of aromatic acids and amides adsorbed on silver colloids by surface-enhanced Raman scattering.

The surface-enhanced raman scattering (SERS) of benzoic acid/benzamide and salicylic acid/salicylamide on silver colloids show important wavenumber shifts with respect to the Raman spectrum of the band assigned to mode 1;ν(ring) when adsorbed on the metal surface (ca. +50 cm(-1)). In the case of the acids, this shift is originated by the deprotonation of the carboxylic group in agreement with the well-known fact that aromatic acids are adsorbed on silver as carboxylates. However, the main conclusion of this work is that a similar behavior is found for the respective amides that do not behave as acids in water solution. The here studied aromatic amides are adsorbed as azanions on silver nanoparticles even at pH 7 and link to the metal through the nitrogen and oxygen atoms of the ionized carboxamide group. This is a very surprising result given that amides are not significantly ionized even at pH 13-14. The deprotonation of these amides is not determined exclusively by the pH, but it is mainly caused by the strong affinity of the anionic species to the metal. Therefore, the SERS must be cautiously used as a universal pH sensor if the adsorption occurs through the ionizable group. In order to support this conclusion, theoretical DFT force field calculations have been carried out, confirming that deprotonated benzamide and salicylamide interact with the metallic surface.

Randomized trial of tacrolimus monotherapy: tacrolimus in combination, tacrolimus alone compared (the TICTAC trial).

BACKGROUND: Prior retrospective studies have suggested that tacrolimus monotherapy is an option associated with excellent outcomes and reduced toxicities. METHOD: We conducted a prospective, randomized, 2-center study of tacrolimus combination therapy vs monotherapy. From April 16, 2004, to September 15, 2005, 58 adult heart transplant patients were studied. All received oral tacrolimus, mycophenolate mofetil, and corticosteroids. Patients were then randomized to a group where mycophenolate was maintained (COMBO) or to a group where it was discontinued (MONO) 14 days post-transplant. Corticosteroids were rapidly withdrawn in both groups between 8 and 12 weeks. RESULT: The primary end point (mean 6-month International Society of Heart and Lung Transplantation biopsy score) was 0.44 +/- 0.04 in the MONO group and 0.60 +/- 0.05 in the COMBO group (p = 0.013, unpaired Student's t-test). The freedom from rejection grade of 2R or higher at 6 and 12 months was 93.3% with MONO and 92.9% with COMBO (p = NS). CONCLUSION: Tacrolimus monotherapy appears to be safe and efficacious in heart transplant recipients and is not associated with excess rejection in the first year post-transplant. Further studies of this approach are warranted.

Mice deficient for the vesicular acetylcholine transporter are myasthenic and have deficits in object and social recognition.

An important step for cholinergic transmission involves the vesicular storage of acetylcholine (ACh), a process mediated by the vesicular acetylcholine transporter (VAChT). In order to understand the physiological roles of the VAChT, we developed a genetically altered strain of mice with reduced expression of this transporter. Heterozygous and homozygous VAChT knockdown mice have a 45% and 65% decrease in VAChT protein expression, respectively. VAChT deficiency alters synaptic vesicle filling and affects ACh release. Whereas VAChT homozygous mutant mice demonstrate major neuromuscular deficits, VAChT heterozygous mice appear normal in that respect and could be used for analysis of central cholinergic function. Behavioral analyses revealed that aversive learning and memory are not altered in mutant mice; however, performance in cognitive tasks involving object and social recognition is severely impaired. These observations suggest a critical role of VAChT in the regulation of ACh release and physiological functions in the peripheral and central nervous system.

Intubación bronquial selectiva: ¿Qué hay de nuevo en la utilidad de las sondas de doble luz? / What is new about usefulness of the double lumen tubes?

El empleo de sondas de doble luz tiene indicaciones precisas en cirugía pulmonar, ortopédica, cardiovascular, oncológica, de tubo digestivo a nivel torácico y en las unidades de cuidados intensivos respiratorios. En la cirugía de tórax, la intubación selectiva proporcional el aislamiento pulmonar evitando la contaminación el pulmón sano con secreciones y/o sangrado proveniente del pulmón enfermo. En las fístulas broncopleurocutáneas, la fuga aérea del volumen corriente se evita con la utilización de estas sondas. Las sondas de doble luz presentan una evolución en sus características físicas desde su aparición hasta la actualidad, la sonda tipo Carlens con espolón carinal tiene la posibilidad de lesionar el árbol traqueobronquial y por contar con una luz interna en forma oval, aumenta la resistencia en la vía aérea, dificultando la ventilación y la aspiración de secreciones; la de tipo Robertshaw, por su material de fabricación y diseño minimiza el trauma de la vía aérea, facilita la técnica de intubación, disminuye la resistencia para la ventilación y proporciona un margen de seguridad adecuado para la intubación bronquial selectiva, dependiendo todo ésto de la marca de fabricación. Por tanto, es imprescindible conocer las características físicas de las sondas, seleccionar el tamaño adecuado para cada paciente, dar la profundidad requerida, obtener el mayor margen de seguridad, aplicar las diferentes técnicas de intubación selectiva y adecuar la presión en el inflado de los globos para minimizar el daño al árbol traqueobronquial y así obtener el mayor beneficio de la utilización de estas sondas