Molecular Transistor Controlled through Proton Transfer.

The potential of proton transfer reactions as a fundamental mechanism to realize a nanoscale molecular transistor is investigated. Employing density functional theory and the nonequilibrium Green's function formalism, we identify molecule-graphene nanojunctions, which exhibit high- and low-conducting states depending on the specific location of protons in the molecular bridge. In addition, we show that an electrostatic gate field can control the proton transfer process and thus allow specific conductance states to be selected. In this way, the current in the junction can be switched on and off as in a field-effect transistor. The underlying mechanism is analyzed in detail.

Dynamical simulation of electron transfer processes in self-assembled monolayers at metal surfaces using a density matrix approach.

A single-particle density matrix approach is introduced to simulate the dynamics of heterogeneous electron transfer (ET) processes at interfaces. The characterization of the systems is based on a model Hamiltonian parametrized by electronic structure calculations and a partitioning method. The method is applied to investigate ET in a series of nitrile-substituted (poly)(p-phenylene)thiolate self-assembled monolayers adsorbed at the Au(111) surface. The results show a significant dependence of the ET on the orbital symmetry of the donor state and on the molecular and electronic structure of the spacer.

Controlling the Conductance of a Graphene-Molecule Nanojunction by Proton Transfer.

The possibility of using single molecule junctions as components of nanoelectronic devices has motivated intensive experimental and theoretical research on the underlying transport mechanism in these systems. In this Letter, we investigate from a theoretical perspective intramolecular proton transfer reactions as a mechanism for controlling the conductance state of graphene-based molecular junctions. Employing a methodology that combines first-principles electronic structure methods with transport approaches, we show that the proton transfer reaction proceeds via a stepwise mechanism, giving rise to several tautomers with different conductance states. The analysis reveals that the relative stability of the tautomers as well as the energy barrier for their interconversion can be controlled by means of an external electrostatic field, which provides a mechanism for switching the nanojunction.

Epidermal growth factor receptor and epididymis invasion as prognostic biomarkers in clinical stage I testicular germ cell tumours.

BACKGROUND: Inguinal orchiectomy is curative in 70-80% of clinical stage I testicular germ cell tumours (CS I TGCT). The identification of patients who are at low risk of relapse is critical to avoid unnecessary treatment. The aim of this study is to explore EGFR, hMLH-1/hMSH-2 and microsatellite instability (MSI) as potential prognostic factors of recurrence in CS I TGCT. METHODS: Fifty-six CS I TGCT patients who underwent inguinal orchiectomy were included in this study. We analysed the relationship between clinicopathological and molecular factors with survival. Analysis of hMLH1, hMSH2 and EGFR expression was carried out by immunohistochemistry. Methylation status of the hMLH1 promoter was determined by pyrosequencing analysis in selected cases. EGFR exons 19, 20, 21 were analysed by PCR labeled-fragments and MSI status was determined using standard Multiplex MSI assays. RESULTS: Classical pathological factors such as lymphovascular invasion, high percentage of embryonal carcinoma, rete testis invasion or tumour size ≥4 cm showed a significant relationship with a higher risk of relapse. Additionally, it was found that an epididymis invasion proved to be a significant independent poor prognostic factor of recurrence (p = 0.001). hMLH1 or hMSH2 expression showed no significant association with risk of relapse and no MSI was found. EGFR expression was observed in 30.4% of samples and its expression was associated with higher risk of relapse (HR 3.5; 95% CI 1.3-9.8; p = 0.016). None of the cases presented EGFR kinase domain mutations. CONCLUSIONS: Epididymis invasion and EGFR expression, but not hMLH-1/hMSH-2 or MSI, could be potentially useful as new prognostic factors of recurrence for CS I TGCT.

Ustekinumab. Neoplasias y otros aspectos de seguridad / Ustekinumab. Neoplasms and Other Safety Aspects

La reciente aparición de nuevos tratamientos biológicos ha permitido un importante avance en el control de la psoriasis. Las interleucinas 12 y 23 desempeñan un papel importante en el control de neoplasias e infecciones. La aparición de nuevas moléculas que bloquean su acción ha reavivado el debate sobre el riesgo de desarrollar neoplasias en los pacientes con psoriasis que reciben este tipo de medicaciones. En este artículo, realizamos una revisión de los estudios de seguridad a tres y cuatro años disponibles hasta la fecha y una revisión de la literatura. Con los datos actuales, se puede concluir que los pacientes expuestos a ustekinumab no presentan mayor riesgo de padecer neoplasias que la población general (AU)

The recent introduction of a new class of biologic agents in psoriasis has led to important advances in the management of this disease. IL-12 and IL-23 play a key role in the control of malignancies and infections. The development of novel molecules capable of blocking the action of these cytokines has rekindled the debate on whether biologic agents increase the risk of malignancy in patients with psoriasis. In this chapter, we review the safety data for patients who have been treated for 3 or 4 years and the literature on the use of ustekinumab. Based on the available evidence, it can be concluded that patients treated with stekinumab do not have a higher risk of malignancy than the general population (AU)

Toward Understanding the Photochemistry of Photoactive Yellow Protein: A CASPT2/CASSCF and Quantum Theory of Atoms in Molecules Combined Study of a Model Chromophore in Vacuo.

Photochemical processes that take place in biological molecules have become an increasingly important research topic for both experimentalists and theoreticians. In this work, we report the reaction mechanism of a model of the photoactive yellow protein (PYP) chromophore in vacuo. The results obtained here, using a strategy based on the simultaneous use of the minimum energy path concept and the quantum theory of atoms in molecules applied to this excited state process, suggest a possible way in which the protein could increase the efficiency of the reaction. The role played by other electronic states of the same and different spin multiplicities in the reaction process is also analyzed, with special emphasis on that played by the lowest-lying triplet state. The possibility of a more complex than expected reaction mechanism is finally discussed, with some suggestions on the possible roles of the protein.

Evaluación de la versión cefálica externa en el manejo de las distocias de presentación / Evaluation of external cephalic version in the management of presentation dystocia

En un trabajo prospectivo y controlado, realizamos versiones externas bajo tocólisis a un grupo de 45 pacientes con presentaciones podálicas y transversas entre las 36 y 40 semanas de gestación. Obtuvimos un 73 por ciento de éxito en el procedimiento con un 49 por ciento de cesáreas en el grupo de estudio comparado con un 87 por ciento en el grupo control. Los factores más importantes en el resultado fueron el tipo de presentación y la paridad. No observamos complicaciones maternas ni fetales significativas