Coaptation/elevation role of the middle deltoid muscle fibers: a static biomechanical pilot study using shoulder MRI.

PURPOSE: It is generally recognized that the middle deltoid muscle fibers (MDMF) have an elevating effect on the humeral head at small abduction angles. These forces are normally counterbalanced by the coaptation effect of the rotator cuff (RC) muscles to maintain shoulder stability. With RC tears, this balance may be jeopardized leading to shoulder dysfunction. Conversely, not all patients with RC tears develop shoulder dysfunction. The purpose of this study was to investigate the coaptation/elevation forces (CEF) ratio of the MDMF in RC tears subjects and in volunteers, using magnetic resonance imaging (MRI). METHODS: Magnetic resonance imaging images in 10 subjects with RC tears and in five volunteers were used to build a three-dimensional model of the shoulder. The CEF ratio of the MDMF was estimated by representing the glenohumeral joint as a pulley. RESULTS: The CEF ratio increased from the posterior to the anterior fibers of the MDMF.The median and interquartile range (IQR) of the CEF ratios of the posterior-third, middle-third, anterior-third and anterior-surface segments of the deltoid were: 0.16 (IQR = 0.23), 0.61 (IQR = 0.4), 1.42 (IQR = 0.41), 1.94 (IQR = 0.56) in subjects, and 0.06 (IQR = 0.24), 0.45 (IQR = 0.28), 1.32 (IQR = 1.01), 1.49 (IQR = 0.39) in volunteers. In the subjects, the CEF ratio of the anterior-surface segment was greater than all other segments (P ≤ 0.03). CONCLUSIONS: The CEF ratio of the MDMF increased from its posterior segment to its anterior segment, indicating a greater stabilizing effect of the anterior segment both in RC tears subjects and in volunteers. Strengthening of the anterior fibers of the MDMF could potentially improve shoulder function in subjects with RC tears.

Electromechanical phase transition in hexacyanometallate nanostructure (Prussian Blue).

This paper demonstrates the importance of the structural changeover in controlling the physical-chemical properties of hexacyanometalate-like materials (Prussian Blue). A meticulous in situ study of compositional variations using electroacoustic impedance techniques associated to electrogravimetric techniques in hexacyanoferrates containing K+ alkali metals reveals the existence of a nanostructural changeover coupled to a change of the magnetic properties of these electromagnetic materials. In the same way, the electroacoustic impedance techniques can be useful both in the understanding and in the in situ monitoring of the structural changeovers and the magnetic behavior of all kinds of materials.

Meningitis aguda recidivante / Recurrent bacterial meningitis

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Resistencias genotípicas a los fármacos antirretrovirales en fracasos terapéuticos con pautas de alta eficacia / Genotypic resistance to antiretroviral drugs in patients with therapeutic failure to highly active antiretroviral therapy

Fundamento: Caracterizar las mutaciones asociadas con resistencia en fracasos virológicos con tratamientos antirretrovirales de gran actividad (TARGA). Métodos: Estudio genotípico de la transcriptasa inversa y de la proteasa del VIH-1 en 33 pacientes con fracaso virológico, pese al buen cumplimiento del tratamiento. Resultados: Se detectaron mutaciones en 32 de los 33 pacientes. En 27 (81,8 por ciento) se trataba de mutaciones primarias: en el gen de la transcriptasa inversa en 26 (78,8 por ciento) y en el de la proteasa en 20 (60,6 por ciento). El 66,6 por ciento presentaba resistencias a dos fármacos y el 60,6 por ciento resistencias a fármacos de los dos principales grupos terapéuticos. En el momento del fracaso, el 72,7 por ciento de los pacientes recibía al menos un fármaco frente al que se identificaron genotipos resistentes; el 48,5 por ciento, dos fármacos, y el 21,2 por ciento, tres fármacos. Conclusiones: La mayoría de los pacientes que fracasan pese al buen cumplimiento del tratamiento con TARGA presen (AU)