RESUMEN
A Fullerene based system is modified in order to increase its solubility and enhance its ability to carry a protein-like structure. The modified structure, which is proposed to act as HIV-1 protease inhibitor, is [C60-C2H4N-(2,4- XCOCH2OH)C6H4], where the X atom is either O, S or Se. The geometry optimization, vibrational spectra and thermodynamics were performed using semiempirical quantum mechanical PM3 method in order to study the proposed compounds. Furthermore, the quantitative structure activity relationship (QSAR) properties of the compounds are calculated at the same level of theory. Results indicate a possible use of the investigated structures as HIV-1 protease inhibitors. The compounds containing oxygen is more stable as compared to the other two compounds.
Asunto(s)
Fulerenos/farmacología , Inhibidores de la Proteasa del VIH/farmacología , Modelos Moleculares , Fulerenos/química , Inhibidores de la Proteasa del VIH/química , Relación Estructura-Actividad CuantitativaRESUMEN
Low-angle x-ray scattering (LAXS) from lyophilized blood and its constituents is characterized by the presence of two peaks in the forward direction of scattering. These peaks are found to be sensitive to the variations in the molecular structure of a given sample. The present work aims to explore the nature of LAXS from a variety of lyophilized biological samples. It also aims to investigate the possibility that a certain biological macromolecule is responsible of the production of LAXS peaks. This is carried out through measurements of LAXS from complex biological samples and their basic constituents. Among the measured samples are haemoglobin (Hb), globin, haem, packed red blood cells, bovine albumin, egg albumin, milk, casein, glutamine, alanine, fat, muscle and DNA. A table containing some characteristic parameters of the LAXS profiles of these samples is also presented. Analysis of measured profiles shows that all lyophilized samples produce at least one relatively broad peak at a scattering angle around 10.35 degrees. The full width at half maximum (FWHM) of this peak varies considerably among the measured samples. Except for milk and casein. one additional peak at a scattering angle around 4.65 degrees is observed only in the LAXS profiles of proteins or protein-rich samples. This fact strongly suggests protein to be the biological macromolecule from which this characteristic peak originates. The same idea is further strengthened through discussion of some previous observations.
Asunto(s)
Análisis Químico de la Sangre/métodos , Líquidos Corporales/química , Rayos X , Eritrocitos/química , Liofilización , Globinas/análisis , Hemoglobinas/análisis , Humanos , Dispersión de Radiación , Sensibilidad y Especificidad , Albúmina Sérica/análisisRESUMEN
The characteristic nature of low-angle x-ray scattering from biological samples and its dependence on molecular structure is a subject of increasing interest. In this work, low-angle x-ray scattering from lyophilized (freeze-dried) whole blood, haemoglobin (Hb), serum and red blood cell membranes is studied. The scattering profiles of these samples are found to be reproducible and characteristic. A number of characterization parameters are introduced, showing significant differences between the investigated samples. The sensitivity of the scattering profiles of whole blood, Hb and serum towards induced molecular level variations is examined after doses of gamma irradiation of 3, 6 and 9 Gy. The full width at half maximum (FWHM) of the second peak of scattering and the percentage ratio of amplitudes of the first and second peaks (I1/I2)% are found to be the parameters most sensitive to irradiation. For all irradiated samples, it is observed that the FWHM of the second peak is always greater than the control, while the ratio (I1/I2)% is always smaller than the control.
Asunto(s)
Sangre , Dispersión de Radiación , Fenómenos Biofísicos , Biofisica , Sangre/efectos de la radiación , Liofilización , Rayos gamma , Hemoglobinas/efectos de la radiación , Humanos , Técnicas In Vitro , Modelos Teóricos , Fotones , Difracción de Rayos X , Rayos XRESUMEN
Design of medical imaging devices based on the detection of low-angle coherent scattering is a subject of increasing interest. The technique is based on the differences in the distribution of photons coherently scattered from different body tissues. Coherent scattering is also useful in monitoring changes that may occur in a healthy tissue (e.g. carcinoma). In this work, low angle scattering properties of some tissues and tissue-equivalent materials are studied. Special care is given to the possibility of distinguishing between tissues of similar water content (e.g. muscle and blood). For this purpose, a Monte Carlo simulation is updated, introducing molecular form factor data, which include molecular interference effects. This program is used to simulate the angular distribution of scattered photons from two tissue-equivalent materials (lucite and water) and three biological samples (muscle, fat and blood). Simulation results agree well with previously measured angular distributions of scattered photons at 59.54 keV. Scattering from water and lucite is also measured at 8.047 keV. The effects of scattering geometry, sample thickness, incident photon energy and tissue type on the angular distribution of scattered photons are investigated. Results reveal the potential of measuring the full width at half maximum (FWHM) of the scattered photon distribution for tissue characterization. Energies up to 13 keV and sample thickness of 0.3 cm reported maximum differences between investigated samples. These conditions are expected to maximize the potential of using coherent scattering set-ups to monitor changes in biological samples even if their water contents are similar. Present results may act as a guide for the optimization of coherent scattering imaging systems.