Desplazamiento epifisario en niños con insuficiencia renal crónica

Para buscar la prevalencia y factores clínicos-bioquímicos implicados en el desarrollo de epifisiolisis en niños con insuficiencia renal crónica, estudiamos 48 pacientes de 8,1+4,2 años, 28 en tratamiento conservador y 20 sometidos a diálisis crónica. Se analizó edad cronológica y de aparición de la insuficiencia renal, años de evolución y de diálisis y enfermedad fundamental y se practicó estudio del metabolismo fosfocálcico y mapa óseo. Cuatro enfermos presentaron epifisiolisis, lo que supone una prevalencia en nuestro medio del 8,3%. Los 4 seguían tratamiento dialítico y la insuficiencia renal se presentó durante la lactancia por una enfermedad renal congenita o de aparición en período neonatal precoz. Bioquímicamente tenían el grado más severo de hiperparal iroidismo con cifras inapropiadamente bajas de calcio y fósforo a pesar de instauración del tratamiento sustitutivo mediante diálisis crónica.Clinical, biochemical and roentgenological features of 48 children with chronic renal failure have been analysed. The prevalence and factors implicated with slipped epiphysis outlined. Four of 48 patients (8.3%) shown roentgenological dates of epiphysiolysis. In this cases, the underlying renal disease was congenital or neonatal, developping renal failure in infancy (average 0.6 months) and had the most severe hyperparathyroidism associated with low calcium and phosphorus level in spite of dialytic treatment

Bacterial Surface Appendages Strongly Impact Nanomechanical and Electrokinetic Properties of Escherichia coli Cells Subjected to Osmotic Stress

The physicochemical properties and dynamics of bacterial envelope, play a major role in bacterial activity. In this study, the morphological, nanomechanical and electrohydrodynamic properties of Escherichia coli K-12 mutant cells were thoroughly investigated as a function of bulk medium ionic strength using atomic force microscopy (AFM) and electrokinetics (electrophoresis). Bacteria were differing according to genetic alterations controlling the production of different surface appendages (short and rigid Ag43 adhesins, longer and more flexible type 1 fimbriae and F pilus). From the analysis of the spatially resolved force curves, it is shown that cells elasticity and turgor pressure are not only depending on bulk salt concentration but also on the presence/absence and nature of surface appendage. In 1 mM KNO3, cells without appendages or cells surrounded by Ag43 exhibit large Young moduli and turgor pressures (∼700–900 kPa and ∼100–300 kPa respectively). Under similar ionic strength condition, a dramatic ∼50% to ∼70% decrease of these nanomechanical parameters was evidenced for cells with appendages. Qualitatively, such dependence of nanomechanical behavior on surface organization remains when increasing medium salt content to 100 mM, even though, quantitatively, differences are marked to a much smaller extent. Additionally, for a given surface appendage, the magnitude of the nanomechanical parameters decreases significantly when increasing bulk salt concentration. This effect is ascribed to a bacterial exoosmotic water loss resulting in a combined contraction of bacterial cytoplasm together with an electrostatically-driven shrinkage of the surface appendages. The former process is demonstrated upon AFM analysis, while the latter, inaccessible upon AFM imaging, is inferred from electrophoretic data interpreted according to advanced soft particle electrokinetic theory. Altogether, AFM and electrokinetic results clearly demonstrate the intimate relationship between structure/flexibility and charge of bacterial envelope and propensity of bacterium and surface appendages to contract under hypertonic conditions

Study of the magnetorheology of aqueous suspensions of extremely bimodal magnetite particles

In this paper we describe the magnetorheological behavior of aqueous suspensions consisting of magnetite particles of two size populations, in the micrometer and nanometer scale, respectively. Previous works on the magnetorheology of oil-based fluids demonstrated that the addition of nanoparticles has a very significant effect on the intensity of the magnetorheological effect. The present contribution confirms such results in the case of aqueous fluids, based on the dependence of the yield stress and the viscosity of the bimodal suspensions on both the composition of the mixtures and the magnetic field strength. It is demonstrated that for a given concentration of micrometer particles, increasing the amount of nanometer magnetite provokes a clear enhancement in the yield stress for all the magnetic fields applied. This is proposed to be due to the formation of heterogeneous aggregates that improve the stability of the suspensions and ease the building of well-arranged field-induced structures. The behavior of both the yield stress and the post-yield viscosity agrees better with the predictions of standard chain models when the relative proportion of both types of particles confers optimum stability to the bimodal dispersions