Deficiencia de vitamina B12 en diabéticos tipo 2 tratados con metformina

Sr. Director: La metformina es uno de los tratamientos hipoglucemiantes más utilizados entre los diabéticos tipo 2. Son conocidos sus efectos secundarios gastrointestinales, causa no despreciable de abandono del tratamiento, pero es menos considerada su relación con la deficiencia de vitamina B12(vit. B12). La evaluación del fármaco (DrugDex) valora la incidencia de deficiencia de vit. B12 en el 7%. Parece que el riesgo de deficiencia aumenta en los pacientes que reciben dosis más altas de metformina y con tratamientos de mayor duración. Algo confirmado en un reciente ensayo clínico aleatorizado multicéntrico con diabéticos tipo 2 dependientes de insulina aleatorizados a recibir 850 mg de metformina o placebo tres veces al día durante 4,3 años..

Influencia de la presión arterial al inicio de las descompensaciones en el pronóstico de pacientes con insuficiencia cardiaca

Fundamento y objetivo: Existe una relación inversa entre las cifras de presión arterial en las descompensaciones y el pronóstico de la insuficiencia cardiaca (IC). Las características de esta relación no son bien conocidas. El objetivo del estudio fue analizar si esta relación se mantiene en una cohorte no seleccionada de pacientes con IC y si el tratamiento la modifica. Material y métodos: Estudio prospectivo de cohortes de pacientes ingresados por IC descompensada en un servicio de Medicina Interna y seguidos ambulatoriamente en una consulta monográfica. Los pacientes fueron agrupados en función de la presión arterial sistólica (PAS) y diastólica (PAD); se analizaron las características clínicas, la mortalidad global y los reingresos al primer, tercer y sexto mes de seguimiento. Resultados: Se incluyeron 221 pacientes tras un ingreso índice por IC. Media de edad: 79, 5 años (DE 8, 09); varones: 115. No hubo diferencias significativas en las características basales de los pacientes en función de los cuartiles de PAS. Los pacientes con menor PAS (Q1) tenían mayor mortalidad (20%, p < 0, 05). No se encontraron diferencias para la PAD. Sin embargo, el análisis de Kaplan-Meier mostró una mayor mortalidad global en los pacientes con menor PAS y PAD (log-rank = 0, 011 y 0, 041, respectivamente). Las características del tratamiento farmacológico no diferían entre los grupos del estudio. Conclusión: En pacientes con IC no seleccionados, las cifras elevadas de PAS al ingreso se asocian con una menor mortalidad durante el seguimiento. El tratamiento farmacológico de la IC no parece influir en la relación inversa entre la PAS al ingreso y la mortalidad. Background and objective An inverse relationship has been described between blood pressure and the prognosis in heart failure (HF). The characteristics of this relationship are not well unknown. The objective of this study was to determine if this relationship is maintained in a non-selected cohort of patients with HF and if it can be modified by treatment. Material and methods Prospective study of cohorts including patients hospitalized for decompensated HF in Internal Medicine departments and followed as outpatients in a monographic consultation. Patients were classified according to their levels of systolic (SBP) and diastolic blood pressure (DBP). Clinical characteristics, all-cause mortality and readmissions after the first, third and sixth month of follow-up were analysed. Results Two hundred and twenty-one patients were included after their admission to the hospital for acute HF. Mean patient age was 79.5 years(SD 8.09); 115 patients were male. No significant differences between SBP quartiles and basal characteristics were found. Patients with lower SBP (Q1) had higher mortality rates (20%, P < .05). No significant differences between mortality/readmissions and DBP were found. However, the Kaplan-Meier analysis showed higher all-cause mortality rates for the group of patients with lower SBP and DBP (log-rank = 0.011 and 0.041, respectively). The pharmacological treatment did not differ significantly between both study groups. Conclusion For non-selected patients suffering HF, higher SBP upon the admission is associated with significantly lower all-cause mortality rates during follow-up. Pharmacological treatment of HF does not seem to influence this inverse relationship between SBP at admission and patient mortality

Atypical charge redistribution over a charge-transfer monolayer on a metal

Peer reviewe

Evidence against a charge density wave on Bi(111)

The Bi(111) surface was studied by scanning tunneling microscopy (STM), transmission electron microscopy (TEM) and angle-resolved photoemission (ARPES) in order to verify the existence of a recently proposed surface charge density wave (CDW) [Ch. R. Ast and H. Hoechst Phys. Rev. Lett. 90, 016403 (2003)]. The STM and TEM results to not support a CDW scenario at low temperatures. Furthermore, the quasiparticle interference pattern observed in STM confirms the spin-orbit split character of the surface states which prevents the formation of a CDW, even in the case of good nesting. The dispersion of the electronic states observed with ARPES agrees well with earlier findings. In particular, the Fermi contour of the electron pocket at the centre of the surface Brillouin zone is found to have a hexagonal shape. However, no gap opening or other signatures of a CDW phase transition can be found in the temperature-dependent data

Charged and metallic molecular monolayers through surface induced aromatic stabilization

Large pi conjugated molecules, when in contact with a metal surface, usually retain a finite electronic gap and, in this sense, stay semiconducting. In some cases, however, the metallic character of the underlying substrate is seen to extend onto the first molecular layer. Here, we develop a chemical rationale for this intriguing phenomenon. In many reported instances, we find that the conjugation length of the organic semiconductors increases significantly through the bonding of specific substituents to the metal surface and through the concomitant rehybridization of the entire backbone structure. The molecules at the interface are thus converted into different chemical species with a strongly reduced electronic gap. This mechanism of surface induced aromatic stabilization helps molecules to overcome competing phenomena that tend to keep the metal Fermi level between their frontier orbitals. Our findings aid in the design of stable precursors for metallic molecular monolayers, and thus enable new routes for the chemical engineering of metal surface

Evidence against a charge density wave on Bi(111)

The Bi(111) surface was studied by scanning tunneling microscopy (STM), transmission electron microscopy (TEM) and angle-resolved photoemission (ARPES) in order to verify the existence of a recently proposed surface charge density wave (CDW) [Ch. R. Ast and H. Hoechst Phys. Rev. Lett. 90, 016403 (2003)]. The STM and TEM results to not support a CDW scenario at low temperatures. Furthermore, the quasiparticle interference pattern observed in STM confirms the spin-orbit split character of the surface states which prevents the formation of a CDW, even in the case of good nesting. The dispersion of the electronic states observed with ARPES agrees well with earlier findings. In particular, the Fermi contour of the electron pocket at the centre of the surface Brillouin zone is found to have a hexagonal shape. However, no gap opening or other signatures of a CDW phase transition can be found in the temperature-dependent data

Mycobacterial Infection in Systemic Lupus Erythematosus: Clinical Significance and Associated Factors. Data from the Registry of Patients with SLE of the Spanish Society of Rheumatology (RELESSER)

Pathophysiology and treatment of rheumatic disease