Ibon Alonso

p53 and cyclin D1 as prognostic factors in squamous cell carcinoma of the larynx

Objectives/Hypothesis Proteins p53 and cyclin D1 play a crucial role in cell cycle control. Protein p53 mutations are one of the most common genetic alterations in human cancer, and cyclin D1 gene amplification has been found to be associated with poor prognosis in different types of tumors. Functional alterations of these proteins may play an important role both in the carcinogenesis of squamous carcinomas of the head and neck and in the clinical evolution of these tumors. The objective of the present study was to evaluate whether the presence of p53 and/or cyclin D1 proteins (detected by immunohistochemical analysis) could serve as relevant variables for the assessment of the prognosis of laryngeal squamous cell carcinoma.

Bent-core liquid crystals in a route to efficient organic nonlinear optical materials

The design, synthesis and nonlinear optical (NLO) response of some bent compounds, at both the molecular and macroscopic level, are reported. Based on a bent-core NLO-phore with a μβ0 in the range of 390 × 10−48 esu (1907 nm), the second order susceptibility tensor for second harmonic generation is evaluated at excitation wavelengths of 1064 and 1600 nm in a mesogenic material with a SmCP mesophase. The NLO coefficients are in the range 10–100 pm V−1. Thus it is deduced that a molecular design leading to bent-core liquid crystals with large β values is a correct strategy to achieve NLO-materials for bulk second order effects.

Liquid crystalline and nonlinear optical properties of bent-shaped compounds derived from 3,4'-biphenylene

The synthesis of different bent-core molecules derived from 3,4′-biphenylene bearing azo, azoxy, imine or ester linkages in their lateral structures is reported. Structure–activity relationships for their liquid crystalline behaviour are discussed. SmCP, USmCP and Colob mesophases are found depending on the type and number of these connecting units. The sequence ester ≈ azoxy > imine > azo can be proposed for the mesophase range, with significant differences observed in terms of mesopahase stabilization. SHG studies on these compounds give nonlinear coefficients in the range of 1–8 pm V−1. The molecular origin for these values is analyzed semi-quantitatively. It was concluded that the SHG performance of bent-core mesogens in general can still be increased substantially. An approach to improve the properties of these materials is briefly outlined.

The SmA phase of a bent-core V-shaped compound: structure and electric-field response

The smectic A (SmA) phase of a V-shaped mesogen with a molecular bending angle of 60° was studied. According to X-ray measurements, the molecules are arranged with the ‘bow-string’ direction parallel to the smectic layer. This point was confirmed by birefringence analysis and the result is compatible with a non-polar structure. A detailed study of the (001) smectic layer reflection versus temperature was also carried out to determine the smectic translational order parameter. The results indicate that the material presents a high degree of translational order. In addition, the electric field response of the material was studied by means of second harmonic generation. This technique turned out to be highly sensitive to small structural distortions due to the V-shape of the constituent molecules.

Local structure of the B4 phase studied by second harmonic generation and X-ray diffraction measurements

Texture observations, second harmonic generation (SHG) and X-ray diffraction measurements have been carried out in the B4 phase of two classical bent-core liquid crystals. Several sample geometries have been used for the different techniques, including a well-aligned cell for the optical studies. An indexation of the whole diffraction diagram was performed on the basis of a three-dimensional lattice. A quantitative analysis of the X-ray data is also reported. The results are compatible with the well-known twist grain boundary (TGB) structure for the B4 phase. However, within the smectic blocks the structure is monoclinic P2, implying an antiferroelectric in-layer arrangement of the molecules instead of the usually accepted ferroelectric. This antiferroelectric packing also explains the low efficiency of the B4 phase for SHG.

Experimental Test of Curvature-Driven Dynamics in the Phase Ordering of a Two Dimensional Liquid Crystal

We study electric field driven deracemization in an achiral liquid crystal through the formation and coarsening of chiral domains. It is proposed that deracemization in this system is a curvature-driven process. We test this prediction using the recently obtained exact result for the distribution of hull-enclosed areas in two-dimensional coarsening with nonconserved scalar order parameter dynamics [J. J. Arenzon et al., Phys. Rev. Lett. 98, 145701 (2007)]. The experimental data are in very good agreement with the theory. We thus demonstrate that deracemization in such bent-core liquid crystals belongs to the Allen-Cahn universality class, and that the exact formula, which gives us the statistics of domain sizes during coarsening, can also be used as a strict test for this dynamic universality class.

Characteristics of a liquid crystal display using optically isotropic phases of bent‐core mesogens

A liquid crystal display (LCD) mode based on non‐oriented samples of bent‐core molecules is presented. The display uses an optically isotropic phase, which is relatively common in bent‐core compounds. The LCD switches between the isotropic phase (off‐state), and a conventional SmCP phase (on‐state) that gives rise to the bright state. The device exhibits good performance: fast response (∼0.1 ms), quite large contrast ratio (>100:1), continuous grey levels and wide viewing angle. These characteristics have been observed down to 80°C. Other remarkable advantages are the robustness of the cells and the simplicity of their preparation, since the material need not be aligned.

Changes in the expression of cyclin dependent kinase inhibitors during differentiation of immortalized fibroblasts into adipocytes

The mechanisms implicated in the differentiation of fibroblastic precursors into adipocytes can be analyzed in vitro using cell models, such as the 3T3-L1 cell line. Since cell differentiation involves an exit from the cell cycle, it is likely that molecules that inhibit proliferation participate in the control of adipogenesis. This study was aimed at determining the role, if any, of several cyclin-dependent kinase (CDK)-inhibitors and the transcription factor C/EBPα in the process of adipocyte differentitation. We analyzed by Western blot the expression of distinct cyclin-dependent kinase (CDK)-inhibitors and C/EBPα during various stages of differentiation of 3T3-L1 cells to adipocytes. We observed specific changes in the expression of CDK inhibitors and C/EBPα, during the various phases of adipogenesis. Levels of p15INK4B were maximal in confluent cells prior to the induction of differentiation and minimal in differentiated cells. Maximal levels of p16INK4A were detected following 48 h of differentiation treatment. Highest levels of p18INK4C were measured during the phase of cell confluence prior to treatment and in differentiated cells. p21CIP1 was expressed during the exponential growth phase, during exit from clonal expansion, and in differentiated cells, while p27KIP1 was found above all in confluent and differentiated cells. The present results support the participation of CDK-inhibitors in the process of in vitro adipogenesis. Specifically, the proteins p18INK4C, p21CIP1 and p27KIP1 seem to play an outstanding role in the maintenance of the differentiated state of adipocytes. Understanding the molecular mechanisms involved in adipocyte differentiation will presumably facilitate the design of new drugs aimed at novel therapeutic targets.

Domain growth in 2d: exact results, simulations and experiments

We obtain the exact distribution of the areas enclosed by domain boundaries (‘hulls’) during the coarsening dynamics of a two‐dimensional nonconserved scalar field. This result represents the first analytical demostration of the dynamical scaling hypothesis for this system. The experimental data for the formation of chiral domains in liquid crystals are in very good agreement with the theory.