María Romero - Academia.edu (original) (raw)

Papers by María Romero

Acta Crystallographica Section C Crystal Structure Communications, 1987

... AND I. CEBALLOS Faculdad de Qufmica, Universidad Autdnoma de Mdxico, Circuito Exterior, Ciuda... more ... AND I. CEBALLOS Faculdad de Qufmica, Universidad Autdnoma de Mdxico, Circuito Exterior, Ciudad Universitaria, Coyoacdn 04510, Mexico DF. ... with specific activity (Guthikonda, Cama & Christensen, 1974; Bose, Ram, Hoffman, Hutchinson & Manhas, 1979; Itil, Saletu & ...

The Journal of Physical Chemistry C, 2010

This paper shows that it is possible to construct well-defined 2D structures at the air-water int... more This paper shows that it is possible to construct well-defined 2D structures at the air-water interface in which the lateral organization is controlled by means of the preparation of mixed films, and selecting the components so that there are attractive interactions between them. The goal here is to establish the lateral connection between components through self-aggregation of the dye. This can be achieved by selecting a suitable balance between the sizes of the hydrophobic and polar groups. In such a way, the domain structure depends on the ability of the tilt dye to fill the available area. Thus, the molecular organization and the domain morphology of mixed films containing dimyristoyl-phosphatidic acid (DMPA) and the hemicyanine dye, 4-[4-(dimethylamino)styryl]-1-docosylpyridinium bromide (SP), have been studied by using Grazing Incidence X-ray Diffraction (GIXD), Brewster angle microscopy (BAM), and reflection spectroscopy at the air-water interface. For this mixed system, the formation of circular domains with bright horizontal regions and dark vertical regions was observed. Furthermore, depending on the temperature, it is observed as branches grow from circular domains, whose brightness depends on the growth direction. Thus, BAM images allow us to observe some branches that, as their growth direction changes, their brightness also changes simultaneously. The GIXD experiment permits us to relate the circular domains with an orthorhombic phase and the branches grown from the circles with an Overbeck phase. In both cases, the formed structures are induced by the hemicyanine aggregation. Circular BAM domain textures have been simulated by using the Fresnel equations for biaxial anisotropic materials.

The Journal of Physical Chemistry C, 2011

This paper analyzes the effect of the reduction of the available area on the aggregation of an he... more This paper analyzes the effect of the reduction of the available area on the aggregation of an hemicyanine dye, 4-[4dimethylamino)styryl]-1-docosylpyridinium bromide (SP), at the airÀwater interface. Mixed films of SP and stearic acid (SA) in 1:1 molar ratio have been studied, and compared with the previously studied films of SP and dimyristoyl-phosphatidic acid (DMPA) in 1:1 molar ratio. With regard to the SP:DMPA films, the replacement of DMPA by SA involves reducing the area available for the hemicyanine aggregation, since the SA molecule provides only an alkyl chain to the set, whereas the DMPA molecule provides two alkyl chains to the set. The SP:SA mixed films have been studied by Grazing Incidence X-ray Diffraction (GIXD), Brewster angle microscopy (BAM), and reflection spectroscopy at the airÀwater interface. LangmuirÀSchaeffer films have been studied by UVÀvis transmission spectroscopy. The SP:SA mixed monolayer forms star-shaped domains with inner textures, indicating anisotropy. Circular domains were observed for the SP:DMPA system. GIXD experiments relate the star-shaped domains with an orthorhombic phase, as for circular domains observed for the SP:DMPA system. The results obtained by reflection and transmission polarized spectroscopy for the SP:SA system showed the splitting of the absorption band of the aggregate. The splitting has been related with a twisting in the hemicyanine groups. The reduction on the available area accounts for the aggregation of the hemicyanine group. The domain shape at the mesoscopic level mainly originated from the interactions between the polar groups and the reduced surface area. The interactions between the alkyl chains are essential to maintain the crystalline structure, although these interactions did not play the main role in the final shape of the domain.

The Journal of Physical Chemistry C, 2009

The molecular organization and the domain morphology of an anionic matrix dimyristoyl-phosphatidi... more The molecular organization and the domain morphology of an anionic matrix dimyristoyl-phosphatidic acid (DMPA) as influenced by the presence of a cationic water-soluble methylene blue (MB) have been studied by using Brewster angle microscopy and reflection spectroscopy at the air-water interface. Mixed monolayers of DMPA:MB, molar ratios 5:1 and 1:1, were formed by the cospreading method. BAM images show particular domain morphologies as a function of the MB density in the mixed film: circular domains for DMPA:MB ) 5:1, and domains with hexagonal shape for DMPA:MB ) 1:1. The reflection measurements during the compression process of the mixed films reveal a blue shift of the visible band with respect to that of the MB monomer. This blue shift is larger for the DMPA:MB ) 5:1 in comparison with that for the 1:1 monolayer, despite lower MB density. By using the extended dipole model, we demonstrate that such blue shift is due to the formation of a 2D hexagonal network of MB molecules underneath the DMPA monolayer in the mixed 1:1 film, while it is due to infinite linear aggregates in the 5:1 monolayer. BAM domain textures have been simulated by using the Fresnel equations for biaxial anisotropic materials. The results fit correctly the predictions of the extended dipole model.

The Journal of Physical Chemistry B, 2009

Molecular and Cellular Endocrinology, 2000

Mitochondria seem to be involved in oxygen radical damage and aging. However, the possible relati... more Mitochondria seem to be involved in oxygen radical damage and aging. However, the possible relationships between oxygen consumption and oxygen radical production by functional mitochondria, and oxidative DNA damage, have not been studied previously. In order to analyze these relationships, male Wistar rats of 12 weeks of age were rendered hyper-and hypothyroid by chronic T 3 and 6-n-propyl-2-thiouracil treatments, respectively. Hypothyroidism decreased heart mitochondrial H 2 O 2 production in States 4 (to 51% of controls; P B0.05) and 3 (to 21% of controls; PB 0.05). In agreement with this, 8-oxo-7,8-dihydro-2%-deoxyguanosine (8-oxodG) decreased in the heart genomic DNA of hypothyroid animals to 40% of controls (PB0.001). Studies with respiratory inhibitors showed that the decrease in oxygen radical generation observed in hypothyroidism occurred at Complex III (mainly) and at Complex I; that decrease was due to the presence of a lower free radical leak in the respiratory chain (P B 0.05). Hyperthyroidism did not significantly change heart mitochondrial H 2 O 2 production since the increase in State 4 oxygen consumption in comparison with control and hypothyroid animals (PB 0.05) was compensated by a decrease in the free radical leak in relation to control animals (PB 0.05). In agreement with this, heart 8-oxodG was not changed in hyperthyroid animals. The lack of increase in H 2 O 2 production per unit of mitochondrial protein will protect mitochondria themselves against self-inflicted damage during hyperthyroidism.

Journal of Inorganic Biochemistry, 2006

The magnetic properties and the ultrastructure, with special emphasis on the nanometric range, of... more The magnetic properties and the ultrastructure, with special emphasis on the nanometric range, of liver tissues in an iron overload rat model have been investigated. The tissues of the animals, sacrificed at different times after a single iron dextran injection, have been characterised by magnetic AC susceptibility measurements together with transmission electron microscopy (TEM) and selected area electron diffraction (SAED) as helping techniques. It has been observed that few days after the iron administration the liver contains at least two iron species: (i) akaganéite nanoparticles, coming from iron dextran and (ii) ferrihydrite nanoparticles corresponding to ferritin. The magnetic susceptibility of the tissues depends not only on the elemental iron content but also on its distribution among chemical species, and varies in a remarkable regular manner as a function of the elapsed time since the iron administration. The results are of relevance with respect to non-invasive techniques for liver iron determination, directly or indirectly based on the magnetic susceptibility of the tissues, as biomagnetic liver susceptometry (BLS) and magnetic resonance (MRI) image treatment.

Inorganic Chemistry, 2009

A cobalt(II) thiosemicarbazonate mesocate has been structurally characterized as an unexpected mi... more A cobalt(II) thiosemicarbazonate mesocate has been structurally characterized as an unexpected mixture of conformational and linkage isomers. Moreover, we have shown that the absence of a nitrogen atom in the spacer of the helicand ligand H(2)L(a), enables the assembly of an achiral mesohelical complex in the case of Co(II) ions.

Inorganic Chemistry Communications, 2004

The electrochemical oxidation of a tin plate in the presence of an acetonitrile suspension of the... more The electrochemical oxidation of a tin plate in the presence of an acetonitrile suspension of the ligand bis-(4-N-methylthiosemicarbazone)-2,6-diacetylpyridine, H 4 DAPTsz-Me, yields the complex Sn(H 2 DAPTsz-Me)(H 2 O) 2 (1). Recrystallisation of 1 in a methanol/acetone solution ...

Free Radical Biology and Medicine, 1999

Steady state protein modification by carbonyl compounds is related to the rate of carbonyl adduct... more Steady state protein modification by carbonyl compounds is related to the rate of carbonyl adduct formation and the half-life of the protein. Thyroid hormones are physiologic modulators of both tissue oxidative stress and protein degradation. The levels of the glycation product N -fructoselysine (FL) and those of the oxidation products, N -(carboxymethyl)lysine (CML) and malondialdehyde-lysine (MDA-lys), identified by GC/MS in liver proteins, decreased significantly in hyperthyroid rats, as well as (less acutely) in hypothyroid animals. Immunoblotting of liver proteins for advanced glycation end-products (AGE) is in agreement with the results obtained by GC/MS. Cytosolic proteolytic activity against carboxymethylated foreign proteins measured in vitro was significantly increased in hypoand hyperthyroidism. Oxidative damage to DNA, estimated as 8-oxo-7,8-dihydro-2Ј-deoxyguanosine (8oxodG), did not show significant differences between groups. The results suggests that the steady state levels of these markers depend on the levels of thyroid hormones, presumably through their combined effects on the rates of protein degradation and oxidative stress, whereas DNA is more protected from oxidative damage.

Clinical Biochemistry, 2004

Objective: To determine the utility of biochemical parameters such as lactic acid (LA), C-reactiv... more Objective: To determine the utility of biochemical parameters such as lactic acid (LA), C-reactive protein (CRP), microalbuminuria (MAU), and base deficit (BD) as early markers of complications in the immediate postoperative evolution of elective open gastrointestinal surgeries.

Clinical Biochemistry, 2002

Objective: Immunosuppressive therapy after liver transplantation may be a risk for kidney dysfunc... more Objective: Immunosuppressive therapy after liver transplantation may be a risk for kidney dysfunction. This work was designed to determine whether Tamm-Horsfall Protein (THP) could be considered as a marker for nephrotoxicity. Design and Methods: THP was determined by an ELISA method in serial 24-h urine from liver transplant patients. Fourteen patients suffered renal insufficiency (LTr 1 ) and 20 showed no acute renal damage (LTr 2 ) after liver transplantation. Results: No clear association could be seen between daily THP excretion and plasma creatinine levels by comparing serial samples collected at the same time. Nevertheless, significant differences were observed in pretransplant THP excretion between both groups of patients. The results (Median/Interquartile Range) were: Controls: 113.2/84.9 to 146.8 mg/24 h (n ϭ 30); LTr 1 : 36.9/18.3 to 54.5 mg/24 h (pϽ Ͻ0.001 with respect to C and LTr 2 ); LTr 2 : 90.8/61.5 to 139.7 mg/24 h. Conclusions: The higher pretransplant synthesis and/or secretion of THP seem to have a protective role on the kidney during and after liver transplantation.

Este trabajo presenta la introducción y utilización de la práctica de desarrollo de software cono... more Este trabajo presenta la introducción y utilización de la práctica de desarrollo de software conocida como Test-Driven Development (TDD) en proyectos de software, expone además que TDD no es solo una metodología de pruebas, sino además una metodología de diseño de software. Está basado en un proyecto de investigación perteneciente a la Universidad Tecnológica Nacional -Facultad Regional Córdoba, con el objetivo de estudiar y enmarcar este tipo de metodologías en la industria, mostrando tanto las particularidades de la misma, como los proyectos en los cuales se aplica, y las ventajas y dificultades que pueden surgir de su adopción. Se explica en el presente trabajo los beneficios y desafíos que se encontraron durante la implementación de TDD en los equipos de software y se resaltan los beneficios relacionados con la calidad del código, de las aplicaciones, la productividad y la comunicación. En contrapartida se evidenciaron desafíos en relación a la experiencia previa de los desarrolladores, ya que TDD resulta más simple de implementar en equipos con experiencia media a alta, en la bibliografía consultada se halló que esto puede ser mitigado implementando mentorías o programación extrema.