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Ítem Estudio de la inducción de movimientos en rodopsina a partir de la foto- ismoerización del retinal utilizando modelos de baja dimensionalidad. Equipo(Universidad Icesi, 2010-01-01) Arango Mambuscay, Carlos AlbertoEl estudio de la dinámica en proteínas se hace por la mecánica clásica, mientras la dinámica en moléculas se debe de estudiar utilizando mecánica cuántica. Hay situaciones en las que una molécula actúa como iniciadora de los movimientos en una macromolécula o una proteína, estudiar este sistema conjunto molécula-proteína es de sumo cuidado. Por una parte, no se puede realizar un cálculo cuántico en un sistema de tal dimensionalidad, y por otra, estudiar la dinámica conjunta clásicamente sería inadecuado y no se obtendrían los efectos cuánticos de importancia en la molécula.
Ítem Simulación de la dinámica de polímeros anfifílicos y su potencial aplicación para encapsular moléculas de fármacos(Universidad Icesi, 2012-08-29) Arango Mambuscay, Carlos Alberto[No contiene resumen]Ítem Atorvastatin protects GABAergic and dopaminergic neurons in the nigrostriatal system in an experimental rat model of transient focal cerebral ischemia.(2014-01-01) Arango Mambuscay, Carlos AlbertoCerebral ischemia is the third leading cause of death and the primary cause of permanent disability worldwide. Atorvastatin is a promising drug with neuroprotective effects that may be useful for the treatment of stroke. However, the effects of atorvastatin on specific neuronal populations within the nigrostriatal system following cerebral ischemia are unknown. OBJECTIVE To evaluate the effects of atorvastatin on dopaminergic and GABAergic neuronal populations in exofocal brain regions in a model of transient occlusion of the middle cerebral artery. MATERIALS AND METHODS Twenty-eight male eight-week-old Wistar rats were used in this study. Both sham and ischemic rats were treated with atorvastatin (10 mg/kg) or carboxymethylcellulose (placebo) by gavage at 6, 24, 48 and 72 hours post-reperfusion. We analyzed the immunoreactivity of glutamic acid decarboxylase and tyrosine hydroxylase in the globus pallidus, caudate putamen and substantia nigra. RESULTS We observed neurological damage and cell loss in the caudate putamen following ischemia. We also found an increase in tyrosine hydroxylase immunoreactivity in the medial globus pallidus and substantia nigra reticulata, as well as a decrease in glutamic acid decarboxylase immunoreactivity in the lateral globus pallidus in ischemic animals treated with a placebo. However, atorvastatin treatment was able to reverse these effects, significantly decreasing tyrosine hydroxylase levels in the medial globus pallidus and substantia nigra reticulata and significantly increasing glutamic acid decarboxylase levels in the lateral globus pallidus. CONCLUSION Our data suggest that post-ischemia treatment with atorvastatin can have neuro-protective effects in exofocal regions far from the ischemic core by modulating the GABAergic and dopaminergic neuronal populations in the nigrostriatal system, which could be useful for preventing neurological disorders.Ítem Classical mechanics of dipolar asymmetric top molecules in collinear static electric and nonresonant linearly polarized laser fields: energy-momentum diagrams, bifurcations and accessible configuration space(World Scientific Publishing, 2008-02-08) Arango Mambuscay, Carlos AlbertoWe study classical energy-momentum ($E$-$m$) diagrams for rotational motion of dipolar asymmetric top molecules in strong external fields. Static electric fields, nonresonant linearly polarized laser fields, and collinear combinations of the two are investigated. We treat specifically the molecules iodobenzene (a nearly prolate asymmetric top), pyridazine (nearly oblate asymmetric top), and iodopentafluorobenzene (intermediate case). The location of relative equilibria in the $E$-$m$ plane and associated bifurcations are determined by straightforward calculation, with analytical results given where possible. In cases where analytical solutions cannot be obtained, we resort to numerical solutions, while keeping a geometrical picture of the nature of the solutions to the fore. The classification we obtain of the topology of classically allowed rotor configuration space regions in the $E$-$m$ diagram is of potential use in characterization of energy eigenstates of the corresponding quantum mechanical problem.Ítem Communication: Conditions for one-photon coherent phase control in isolated and open quantum systems.(AIP Publishing, 2010-10-15) Arango Mambuscay, Carlos AlbertoCoherent control of observables using the phase properties of weak light that induces one-photon transitions is considered. Measurable properties are shown to be categorizable as either class A, where control is not possible, or class B, where control is possible. Using formal arguments, we show that phase control in open systems can be environmentally assisted.Ítem Optimal control of wave-packets: a semiclassical approach(Taylor & Francis, 2014-02-16) Arango Mambuscay, Carlos AlbertoWe studied the optimal quantum control of a molecular rotor in tilted laser fields using the time-sliced Herman–Kluk propagator for the evaluation of the optimal pulse and the light–dipole interaction as the control mechanism. The proposed methodology was used to study the effects of an optimal pulse on the evolution of a wave-packet in a double-well potential and in the effective potential of a molecular rotor in a collinear tilted fields setup. The amplitude and frequency of the control pulse were obtained in such a way that the transition probability between two rotational wave-packets was maximised.Ítem Rapid differentiation of isobaric and positional isomers of structurally related glycosides from Phytolacca bogotensis.(Wiley, 2009-09-25) Arango Mambuscay, Carlos AlbertoThrough the action of glycosyltransferases, a plant can biosynthetically assemble small different aglycons or 'templates' to various polysaccharides to produce numerous glycoconjugates differing in the type of the attached aglycon, the anomeric configuration of C-1 of the glycosylating sugar, the type of sugar and the different position of attachments of the sugar unit present in the polysaccharide chain. The position of attachments and the anomeric configuration of the different sugar present in the polysaccharide create the opportunity to generate molecules with either the same or very close molecular weights, which have relative structural similarity--forming isobaric and positional isomers. Although isomeric differentiation was once considered outside of the domain of mass spectrometry, this task can now be resolved using tandem mass spectrometry. In a standardized purified glycoconjugate fraction (SPT01) from Phytolacca bogotensis, we report conventional electrospray ionization mass spectrometry and collision-induced dissociation (CID) MS/MS parameters which favored the formation of characteristic product ions. This allowed us to suggest the type of sugar linkages present in a specific glycoconjugate. Ten new glycoconjugate are described from this plant and another twelve known saponins were structurally characterized using the automatic MSn acquisition mode. The differentiation of two pairs of positional isomers and four isobaric glycosides and the production of a library of 30 glycosides present in P. bogotensis were accomplished.Ítem Molecular Dynamics of a Water-Absorbent Nanoscale Material Based on Chitosan(American Chemical Society, 2016-03-03) Borca, Carlos H.Although hydrogels have been widely investigated for their use in materials science, nanotechnology, and novel pharmaceuticals, mechanistic details explaining their water-absorbent features are not well understood. We performed an all-atom molecular dynamics study of the structural transformation of chitosan nanohydrogels due to water absorption. We analyzed the conformation of dry, nanoscaled chitosan, the structural modifications that emerge during the process of water inclusion, and the dynamics of this biopolymer in the presence of nature’s solvent. Two sets of nanoscaled, single-chained chitosan models were simulated: one to study the swelling dependence upon the degree of self-cross-linking and other to observe the response with respect to the degree of protonation. We verified that nanohydrogels keep their ability to absorb water and grow, regardless of their degree of cross-linking. Noteworthy, we found that the swelling behavior of nanoscaled chitosan is pH-dependent, and it is considerably more limited than that of larger scale hydrogels. Thus, our study suggests that properties of nanohydrogels are significantly different from those of larger hydrogels. These findings might be important in the design of novel controlled-release and targeted drug-delivery systems based on chitosan.Ítem Communication: One-photon phase control of cis-trans isomerization in retinal(AIP Publishing, 2013-02-21) Brumer, PaulWe computationally demonstrate the one-photon phase control of retinal isomerization under conditions of low laser intensity. The calculations, utilizing the multiconfigurational time dependent Hartree method, include coupling between the two modes that are active in isomerization and the background molecular vibrational environment. Noting previously unsuccessful computations highlights the significance of this result.Ítem Estudio computacional de glicosilación y fosforilación de proteínas involucradas en procesos neurodegenerativos(Universidad Icesi, 2012-08-29) Borca, C HLa enfermedad cerebrovascular es la primera causa de incapacidad física en el mundo y la tercera causa de muerte [1], además genera cuantiosos gastos para los sistemas de salud. Hasta el momento las estrategias farmacológicas para mitigar sus efectos han sido inefectivas. El proceso neurodegenerativo causado por esta enfermedad se relaciona con mecanismos de control de la supervivencia y muerte celular, en los cuales la proteína AKT juega un importante papel [2,3].