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1.
Int Urol Nephrol ; 47(8): 1403-8, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26152646

RESUMEN

It is known that the common physiological denominator of the ageing process is an attenuation of functional performance with respect to the situation of young people and adults. However, since the first cohort-based longitudinal studies, it has not been possible to establish a "linear" relationship between age and glomerular filtration in all cases. This does not mean that there is no physiological ageing process at all; in addition to those already elucidated, its mechanisms include cell senescence, podocyte dysfunction, a vitamin D deficiency, and homozygotic forms of the MYH9 gene. The aim of the present work was to analyse the prevalence of chronic kidney disease (CKD) and, where possible, the correlation between CKD, defined by an eGFR < 60 ml/min/1.73 m(2), plasma 25(OH)D3 levels and the MYH9 gene in a population of elderly and very elderly persons. These parameters have not been evaluated previously in populations of elderly and very elderly patients. It is concluded that a moderate decrease in the eGFR occurs with age. This does not imply the presence of CKD in elderly people, since in most individuals the reduced eGFR is not accompanied by anaemia, and no individuals show hypocalcaemia, hyperphosphataemia or a high Alb/Cr ratio. Here we observed a lower Hb level and an elevated Alb/Cr ratio in subjects heterozygotic for the MYH9 gene. This could be interpreted in the sense that the gene could exert some protective effect on renal function, whereas the heterozygotic form (allele A) of the MYH9 gene could be considered a very early marker, a new risk factor for the appearance of CKD, or a sign of renal frailty in elderly people.


Asunto(s)
Envejecimiento , Calcifediol/sangre , ADN/genética , Tasa de Filtración Glomerular/fisiología , Proteínas Motoras Moleculares/genética , Cadenas Pesadas de Miosina/genética , Polimorfismo Genético , Insuficiencia Renal Crónica/genética , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Biomarcadores/sangre , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proteínas Motoras Moleculares/metabolismo , Cadenas Pesadas de Miosina/metabolismo , Insuficiencia Renal Crónica/sangre , Insuficiencia Renal Crónica/fisiopatología , Factores de Riesgo , Adulto Joven
2.
Nefrologia ; 31(5): 614-6, 2011.
Artículo en Inglés, Español | MEDLINE | ID: mdl-21959736
12.
Eur Spine J ; 15(1): 74-81, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-15864671

RESUMEN

A comparison between an unconstrained and a partially constrained system for in vitro biomechanical testing of the L5-S1 spinal unit was conducted. The objective was to compare the compliance and the coupling of the L5-S1 unit measured with an unconstrained and a partially constrained test for the three major physiological motions of the human spine. Very few studies have compared unconstrained and partially constrained testing systems using the same cadaveric functional spinal units (FSUs). Seven human L5-S1 units were therefore tested on both a pneumatic, unconstrained, and a servohydraulic, partially constrained system. Each FSU was tested along three motions: flexion-extension (FE), lateral bending (LB) and axial rotation (AR). The obtained kinematics on both systems is not equivalent, except for the FE case, where both motions are similar. The directions of coupled motions were similar for both tests, but their magnitudes were smaller in the partially constrained configuration. The use of a partially constrained system to characterize LB and AR of the lumbosacral FSU decreased significantly the measured stiffness of the segment. The unconstrained system is today's "gold standard" for the characterization of FSUs. The selected partially constrained method seems also to be an appropriate way to characterize FSUs for specific applications. Care should be taken using the latter method when the coupled motions are important.


Asunto(s)
Fenómenos Biomecánicos , Vértebras Lumbares/fisiología , Rango del Movimiento Articular/fisiología , Rotación , Sacro/fisiología , Anciano , Anciano de 80 o más Años , Cadáver , Adaptabilidad , Diseño de Equipo , Seguridad de Equipos , Femenino , Historia del Siglo XVIII , Humanos , Masculino , Persona de Mediana Edad , Ortopedia/métodos , Sensibilidad y Especificidad , Estrés Mecánico
13.
Phys Rev E Stat Nonlin Soft Matter Phys ; 71(4 Pt 1): 041503, 2005 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-15903673

RESUMEN

The viscosity near the critical point in nitrobenzene+hexane and nitrobenzene+heptane binary systems was studied by examining the viscosity values for critical mixtures at a variable temperature as obtained with a falling-ball viscometer. The regular part of the viscosity of the critical mixtures was calculated by interpolating measurements made at noncritical concentrations. Because viscosity anomaly studies must be conducted at zero shear, a method allowing the estimation of the effective shear for this type of viscometer was developed with a view to introducing the corrections required. This methodology was used to determine the critical exponent for the viscosity anomaly in nitrobenzene+hexane and nitrobenzene+heptane systems, which were found to be 0.0422+/-0.0004 and 0.0432+/-0.0013 , respectively, very consistent with the accepted value: 0.043.

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