Multi-faceted Characterization of Wet-milled Griseofulvin Nanosuspensions for Elucidation of Aggregation State and Stabilization Mechanisms.

Characterization of wet-milled drug suspensions containing neutral polymer-anionic surfactant as stabilizers poses unique challenges in terms of assessing the aggregation state and examining the stabilization mechanisms. Using a multi-faceted characterization method, this study aims to assess the aggregation state of wet-milled griseofulvin (GF) nanosuspensions and elucidate the stabilization mechanisms and impact of stabilizers. Two grades, SSL and L, of hydroxypropyl cellulose (HPC) with molecular weights of 40 and 140 kg/mol, respectively, were used as a neutral stabilizer at concentrations varying from 0 to 7.5% (w/w) without and with 0.05% (w/w) sodium dodecyl sulfate (SDS). The aggregation state was examined via laser diffraction, scanning electron microscope (SEM) imaging, and rheometry. Zeta potential, stabilizer adsorption, surface tension, and drug wettability were used to elucidate the stabilization mechanisms. The results suggest that deviation from a uni-modal PSD and pronounced pseudoplasticity with power-law index lower than one signify severe aggregation. Polymer or surfactant alone was not able to prevent GF nanoparticle aggregation, whereas HPC-SDS combination led to synergistic stabilization. The effect of polymer concentration was explained mainly by the stabilizer adsorption and partly by surface tension. The synergistic stabilization afforded by HPC-SDS, traditionally explained by electrosteric mechanism, was attributed to steric stabilization provided by HPC and enhanced GF wettability/reduced surface tension provided by SDS. Zeta potential results could not explain the mitigation of aggregation by HPC-SDS. Overall, this study has demonstrated that the elucidation of the complex effects of HPC-SDS on GF nanosuspension stability entails a multi-faceted and comprehensive characterization approach.

[Cholesterol crystals pericarditis]. / Pericarditis con cristales de colesterol.

Cholesterol pericarditis is an uncommon, specific form of pericardial disease that is characterized by the presence of cholesterol crystals in pericardial fluid. The etiology may be either idiopathic or in association with systemic disorders such as tuberculosis, rheumatoid arthritis, myxedema or hypercholesterolemia. We report a case of cholesterol pericarditis in a 51-year-old male who was diagnosed with chronic renal failure due to polycystic kidney disease. To our knowledge no similar cases have been reported to date in the literature.

[Exercise-induced atrioventricular block. Significance of the ischemic component. Report of 4 new cases]. / Bloqueo auriculoventricular inducido por el esfuerzo. Importancia del componente isquémico. Presentación de cuatro nuevos casos.

We report four new cases of exercise-induced atrio-ventricular block (appearing during treadmill exercise testing). The mechanism was ischemia in two patients and the conduction disturbance disappeared after coronary artery bypass grafting. The literature on this matter is reviewed. Also the etiology, the natural history and management are discussed in these cases.

[A primary epithelioid hemangioendothelioma localized in the pulmonary valve]. / Hemangioendotelioma epitelioide primario localizado en la válvula pulmonar.

A case of epithelioid haemangioendothelioma sited at pulmonary valve, with an excrescence growing invading pulmonary artery troncus and its principal branches, in a 56-year-old woman is reported. The evolutive behavior simulated some clinical situations which made difficult the diagnosis: a mild-moderate pulmonary stenosis, a general syndrome, and, finally, an acute pulmonary thromboembolism that carried to an aggressive management which conducted to the entity diagnosis.

[Right ventricular function and effort tolerance in patients with chronic congestive heart insufficiency. A cross-over double-blind study]. / Función ventricular derecha y tolerancia al esfuerzo en los pacientes con insuficiencia cardíaca congestiva crónica. Estudio cruzado a doble ciego.

We tried to assess the value of both ventricular function changes and its correlation with maximal exercise capacity in patients with chronic heart failure. For this purpose, a double blind crossover study was designed, and the change in the exercise tolerance and both ventricular ejection fraction were evaluated. When compared with digoxin treatment (p less than 0.01) and with a control-period (p less than 0.001), the captopril increases total exercise time significantly. The response of right ventricular ejection fraction was similar. The changes in right ventricular ejection fraction, but not those of left ventricular ejection fraction, correlated with the variations of exercise time (r = 0.67). These facts suggest that right ventricular function is an important determinant of exercise capacity in patients with chronic heart failure and that its behaviour explain, in part, the response to captopril treatment.