Ana Martin-Herranz - Academia.edu (original) (raw)

Papers by Ana Martin-Herranz

Critical Reviews in Oncology Hematology, Oct 1, 2015

Vitamin D review and supplementation recommendations for women diagnosed with breast or ovary can... more Vitamin D review and supplementation recommendations for women diagnosed with breast or ovary cancer have been defined in the context of bone health and cancer prognosis/risk taking as reference wider cancer patients and postmenopausal women. This specific group has been selected due to its higher osteoporosis risk versus postmenopausal women. Early vitamin D supplementation could help maintain bone health, as well as potentially enhance cancer survival rate. Factors considered for supplementation include daily dose, periodicity, chemical form, administration, and serum levels. Sufficient vitamin D serum levels are recommended to be above 30 ng/ml (75 nmol/l). Maintenance oral supplementation equivalent to a minimum daily dosage of 800-1000 IU (20-25 g) cholecalciferol provided in a daily to monthly bases is preferred, also advised to start with higher dosages when vitamin D serum levels are <10 ng/ml (25 nmol/l). Calcidiol supplementation is more effective, making it advantageous for cases with very low or difficult to raise vitamin D serum levels.

EN ESTE TRABAJO SE HA REALIZADO UN ESTUDIO EXHAUSTIVO DEL COMPORTAMIENTO DE SISTEMAS MICELARES (I... more EN ESTE TRABAJO SE HA REALIZADO UN ESTUDIO EXHAUSTIVO DEL COMPORTAMIENTO DE SISTEMAS MICELARES (IONICOS Y NO IONICOS) EN LAS PROXIMIDADES DE PUNTOS CRITICOS DE TIPO LIQUIDO-LIQUIDO.SE HA ANALIZADO EL COMPORTAMIENTO DEL PARAMETRO DE ORDEN EN LOS DISTINTOS SISTEMAS, CONFIRMANDOSE LA VALIDEZ DE LOS EXPONENTES CRITICOS ISING 3D. SE HA REALIZADO UN ESTUDIO DE LA LONGITUD DE CORRELACION Y LA SUSCEPTIBILIDAD OSMOTICA DE LOS DISTINTOS SISTEMAS EN FUNCION DE LA TEMPERATURA, TANTO PARA LA COMPOSICION CRITICA COMO PARA OTROS NO CRITICOS. ESTOS DATOS, NO SOLO CONFIRMAN LA VALIDEZ DE LOS EXPONENTES ISING 3D, SINO QUE HAN PUESTO DE MANIFIESTO LAS NOTABLES LIMITACIONES DEL LLAMADO MODELO LINEAL. EL ESTUDIO DEL COMPORTAMIENTO CRITICO DE LOS COEFICIENTES DE TRANSPORTE SE HA REALIZADO EN BASE A MEDIDAS DE VISCOSIDAD Y DE DISPERSION INELASTICA DE LUZ. EN ALGUNOS DE LOS SISTEMAS SE HA PUESTO DE MANIFIESTO POR PRIMERA VEZ LA EXISTENCIA DE DOS MODOS DE RELAJACION EN LA FUNCION DE AUTOCORRELACION. UNO ASO...

Critical Reviews in Oncology/Hematology, 2015

$Research paper thumbnail of In situ X-ray Diffraction Studies of a Multilayered Membrane Fluid under Confinement and Shear$

The Journal of Physical Chemistry, 1996

In the "large aggregates" region of the phase diagram of the system C 12 E 5 /D 2 O the mutual di... more In the "large aggregates" region of the phase diagram of the system C 12 E 5 /D 2 O the mutual diffusion coefficient of mixtures with critical and noncritical composition is determined by dynamic light scattering (compositions: 0.23 × 10-2 e y e 10.01 × 10-2 ; y c) 1.08 × 10-2 ; y, mass fraction of C 12 E 5). In all experiments the diffusion coefficient decreases with increasing temperatures, approaching the liquid/liquid coexistence curve at fixed values of y. This is a system independent property observed in "simple" as well as in "complex" binary mixtures with a miscibility gap. The change of size and shape of C 12 E 5 micelles with composition and temperature in aqueous solutions reported for the "large aggregates" region appears to be the result of concentration fluctuations existing in a wide temperature and composition region below the binodal curve. Approaching T p (T c) the diffusive property of the mixtures is dominated by the dynamics of concentration fluctuations.

Physical Review E, 1996

Page 1. Double-exponential relaxation near the critical point of an ionic micellar system Ana Mar... more Page 1. Double-exponential relaxation near the critical point of an ionic micellar system Ana Martın, Francisco Ortega, and Ramón G. Rubio Departamento de Quımica Fısica I, Facultad de Ciencias Quımicas, Universidad Complutense ...

Non-Viral Vectors for Gene Therapy, Second Edition: Part 1, 2005

Cationic liposomes (CLs) are used as non-viral vectors in worldwide clinical trials of gene thera... more Cationic liposomes (CLs) are used as non-viral vectors in worldwide clinical trials of gene therapy. Among other advantages, CL-DNA complexes have the ability to transfer very large genes into cells. However, since the understanding of their mechanisms of action is still incomplete, their transfection efficiencies remain low compared to those of viruses. We describe recent studies which have started to unravel the relationship between the distinct structures and physicochemical properties of CL-DNA complexes and their transfection efficiency by combining several techniques: synchrotron X-ray diffraction for structure determination, laser-scanning confocal microscopy to probe the interactions of CL-DNA particles with cells, and luciferase reporter-gene expression assays to measure transfection efficiencies in mammalian cells. Most CL-DNA complexes form a multilayered structure with DNA sandwiched between the cationic lipids (lamellar complexes, L(alpha)(C)). Much more rarely, an inverted hexagonal structure (H(II)(C)) with single DNA strands encapsulated in lipid tubules is observed. An important recent insight is that the membrane charge density sigma(M) of the CL-vector, rather than, for example, the charge of the cationic lipid, is a universal parameter governing the transfection efficiency of L(alpha)(C) complexes. This has led to a new model of the intracellular release of L(alpha)(C) complexes, through activated fusion with endosomal membranes. In contrast to L(alpha)(C) complexes, H(II)(C) complexes exhibit no dependence on sigma(M), since their structure leads to a distinctly different mechanism of cell entry. Surface-functionalized complexes with poly(ethyleneglycol)-lipids (PEG-lipids), potentially suitable for transfection in vivo, have also been investigated, and the novel aspects of these complexes are discussed.

Physical Review E, 1998

The critical behavior of the dodecilammonium chloride plus water plus KCl system has been studied... more The critical behavior of the dodecilammonium chloride plus water plus KCl system has been studied by static and dynamic light scattering. The line of critical points intercepts a surface corresponding to first-order phase transitions at low concentrations of KCl and low temperature, thus leading to the existence of a critical end point. The correlation length and osmotic susceptibility experimental data can be well described by simple scaling laws with three-dimensional Ising critical exponents for all the salt concentrations. This suggests that approaching the surface of first-order phase transitions does not affect the nature of the liquid-liquid critical point, in agreement with the predictions of Fisher and Barbosa ͓Phys. Rev. B 43, 11 177 ͑1991͔͒. Far from the critical temperature T c single-exponential correlation functions are found at all the salt concentrations studied. However, as T c is approached a new slower relaxation mode appears and becomes dominant near T c. This behavior is independent of ͓KCl͔ and thus of the proximity to the first-order transition surface. The twoexponential decay has been analyzed in terms of the asymmetric H model of Hohenberg and Halperin ͓Rev. Mod. Phys. 49, 435 ͑1977͔͒, which allows one to separate the background and critical contributions. The contribution of the critical concentration fluctuations can be very well described in terms of the mode-coupling theory. The analysis of the relative weight of the two contributions has allowed us to conclude that background and critical contributions are very weakly coupled. ͓S1063-651X͑98͒03108-0͔

$Research paper thumbnail of The x-ray surface forces apparatus for simultaneous x-ray diffraction and direct normal and lateral force measurements$

Review of Scientific Instruments, 2002

Physical Review Letters, 2003

DNA condensation in vivo relies on electrostatic complexation with small cations or large histone... more DNA condensation in vivo relies on electrostatic complexation with small cations or large histones. We report a synchrotron x-ray study of the phase behavior of DNA complexed with synthetic cationic dendrimers of intermediate size and charge. We encounter unexpected structural transitions between columnar mesophases with in-plane square and hexagonal symmetries, as well as liquidlike disorder. The isoelectric point is a locus of structural instability. A simple model is proposed based on competing long-range electrostatic interactions and short-range entropic adhesion by counterion release.

Physical Review Letters, 2001

The second generation x-ray surface forces apparatus (XSFA-II) allows for the first time simultan... more The second generation x-ray surface forces apparatus (XSFA-II) allows for the first time simultaneous in situ small-angle x-ray scattering and surface force measurements. We have used the XSFA-II to monitor shear-induced orientational transitions in a lyotropic model lubricant system. Upon applying small shear amplitudes (ϳ20 mm) to a relatively thick (ϳ800 mm) film, we observed evidence for the formation of an orientational boundary layer at the shearing surface. Time-resolved x-ray diffraction revealed the gradual transition to shear-favored orientation by growth of the boundary layer.

Langmuir, 1997

ABSTRACT Plots of the temperature dependence of the shear viscosity η of C12E5/D2O mixtures with ... more ABSTRACT Plots of the temperature dependence of the shear viscosity η of C12E5/D2O mixtures with compositions in the range 0.60 × 10-2 < y < 10.08 × 10-2 (critical composition yc = 1.08 × 10-2; y, mass fraction of C12E5) are S-formed (a shallow minimum at a lower temperature Tη,min and a maximum at a higher temperature Tη,max). The measurements are carried out in the temperature range 5 °C < T < TP; TP ≈ 30 °C approaching the lower part of the binodal curve (TP, temperature of phase separation of the mixture). In the temperature range (TP − Tη,max) the viscosity decreases with increasing temperatures. At compositions y < 0.60 × 10-2 the viscosity decreases with increasing temperature monotonically. The self-diffusion coefficient of C12E5 in C12E5/D2O mixtures is measured in the same temperature and composition range. The findings of both types of experiments are rationalized in terms of a model developed by Nilsson et al. (J. Phys. Chem. 1983, 87, 1377). The results give support to the hypothesis that the characteristic features of the temperature and composition dependence of both transport coefficients in the large aggregate region of the phase diagram have a common cause: The structural dynamics of the large micellar aggregates increases approaching the liquid/liquid coexistence curve at compositions y > yc. Concentration fluctuations with long range correlations appear to be involved in this process.

The Journal of Chemical Physics, 1994

Critical behavior of ionic micellar systems at different salt concentrations. [The Journal of Che... more Critical behavior of ionic micellar systems at different salt concentrations. [The Journal of Chemical Physics 101, 6874 (1994)]. Ana Martín, Iñaki López, Francisco Monroy, Arturo G. Casielles, Francisco Ortega, Ramón G. Rubio. Abstract. ...

International Journal of Thermophysics - INT J THERMOPHYS, 1999

The coexistence curves of the system dodecylammonium chloride+water+KCl have been obtained for di... more The coexistence curves of the system dodecylammonium chloride+water+KCl have been obtained for different salt concentrations. We found that the asymptotic behavior of the order parameter can be describe using extended scaling and the usual Ising value for the ß=0.325 exponent. The static light scattering data for the critical composition are also compatible with the Ising value v=0.63. Dynamic light scattering results have been obtained near the liquid–liquid critical point. The correlation functions have been found to be single-exponential for temperatures well above critical, while a second decay process at longer times becomes evident for T-Tc<4K. These correlation functions can be fitted to the sum of two exponential functions. The diffusion coefficient associated with concentration fluctuations has been calculated from both relaxation modes. It has been analyzed in terms of the predictions of the mode-coupling theory. These results, together with correlation length and visco...

Biophysical Journal, 2004

Cationic lipid-DNA (CL-DNA) complexes are abundantly used in nonviral gene therapy clinical appli... more Cationic lipid-DNA (CL-DNA) complexes are abundantly used in nonviral gene therapy clinical applications. Surface functionality is the next step in developing these complexes as competent, target-specific gene carriers. Poly(ethylene glycol) (PEG) is the natural choice to serve as a protective coat or act as a tether for a specific ligand on the surface of these complexes due to its biocompatibility and ability to convey stealth-like properties. Understanding the effect of PEG on the internal structure and surface properties of CL-DNA complexes is essential in developing vectors with more complex derivatives of PEG, such as Arg-Gly-Asp (RGD)-based peptide-PEG-lipids. We report on x-ray diffraction studies to probe the internal structure of CL-DNA complexes consisting of a ternary mixture of cationic lipids, neutral lipids, and PEG-lipids. The PEG-coated complexes are found to exhibit a structure consistent with the lamellar phase. In addition, three distinct DNA interchain interaction regimes were found to exist, due to a), repulsive long-range electrostatic forces; b), short-range repulsive hydration forces; and c), novel polymer-induced depletion attraction forces in two dimensions. Optical microscopy and reporter gene assays further demonstrate the incorporation of the PEG-lipids into the lamellar CL-DNA complexes under biologically relevant conditions, revealing surface modification. Both techniques show that PEG-lipids with a polymer chain of molecular weight 400 do not provide adequate shielding of the PEGylated CL-DNA complexes, whereas PEG-lipids with a polymer chain of molecular weight 2000 confer stealth-like properties. This surface functionalization is a crucial initial step in the development of competent vectors for in vivo systemic gene delivery and suggests that a second type of surface functionality can be added specifically for targeting by the incorporation of peptide-PEG-lipids.