RESUMO
Precipitates (ppts) in new generation aluminum-lithium alloys (AA2099 and AA2199) were characterised using scanning and transmission electron microscopy and atom probe tomography. Results obtained on the following ppts are reported: Guinier-Preston zones, T1 (Al2 CuLi), ß' (Al3 Zr) and δ' (Al3 Li). The focus was placed on their composition and the presence of minor elements. X-ray energy-dispersive spectrometry in the electron microscopes and mass spectrometry in the atom probe microscope showed that T1 ppts were enriched in zinc (Zn) and magnesium up to about 1.9 and 3.5 at.%, respectively. A concentration of 2.5 at.% Zn in the δ' ppts was also measured. Unlike Li and copper, Zn in the T1 ppts could not be detected using electron energy-loss spectroscopy in the transmission electron microscope because of its too low concentration and the small sizes of these ppts. Indeed, Monte Carlo simulations of EEL spectra for the Zn L2,3 edge showed that the signal-to-noise ratio was not high enough and that the detection limit was at least 2.5 at.%, depending on the probe current. Also, the simulation of X-ray spectra confirmed that the detection limit was exceeded for the Zn Kα X-ray line because the signal-to-noise ratio was high enough in that case, which is in agreement with our observations.
RESUMO
There are emerging ethical issues with regards to the use of animals in the early stages of drug discovery for anti-inflammatory and degenerative diseases from natural products using the activity-directed isolation pathways when many compounds (eg > 100) are present in the crude extract or fraction and are to be tested. The above-mentioned is the main reason for proposing the use of the in vitro anti-denaturation (stabilization) effects of heat treated (immunogenic) bovine serum albumin (BSA) as an assay. Current methods used for detecting and isolating a wide range of anti-inflammatory compounds in the early stages of the drug discovery process utilize a large number of animals. When BSA is heated and is undergoing denaturation, it expresses antigens associated to Type III hyper-sensitive reaction and which are related to diseases such as serum sickness, glomerulonephritis, rheumatoid arthritis and systemic lupus erythematosus. Thus, the assay that is being proposed should be applicable to the discovery of drugs for treating the above mentioned diseases and others, once the compounds stabilize the denaturation process.
Actualmente surgen problemas éticos en relación con el uso de animales en las etapas tempranas del descubrimiento de medicamentos anti-inflamatorios y contra enfermedades degenerativas, a partir de productos naturales, usando vías de aislamiento dirigido por actividad, cuando muchos compuestos están presentes (p.ej. > 100) en la fracción o extracto crudo, y deben ser probados. Lo anterior representa la razón principal para proponer el uso de los efectos de la anti-desnaturalización (estabilización) in vitro de la albúmina sérica bovina (inmunogénica) tratada con calor (ASB) como ensayo. Los métodos corrientes usados para detectar y aislar una amplia gama de compuestos anti-inflamatorios en las etapas tempranas del proceso de descubrimiento del medicamento, utilizan un gran número de animales. Cuando la ASB es calentada y sometida a un proceso de desnaturalización, expresa antígenos en relación con la reacción hipersensitiva de tipo III, relacionada a su vez con enfermedades tales como la enfermedad del suero, la glomerulonefritis, la artritis reumatoide, y el lupus sistémico y eritematoso. De este modo, el ensayo que aquí proponemos debe ser aplicable al descubrimiento de medicamentos para el tratamiento de las enfermedades anteriormente mencionadas y otras, una vez que los compuestos estabilicen el proceso de desnaturalización.
Assuntos
Animais , Bovinos , Anti-Inflamatórios/sangue , Técnicas In Vitro , Preparações de Plantas/farmacologia , Desnaturação Proteica/efeitos dos fármacos , Soroalbumina Bovina/análise , Bioensaio , Descoberta de Drogas , Temperatura Alta/efeitos adversos , Doenças do Sistema Imunitário/tratamento farmacológico , Programas de RastreamentoRESUMO
There are emerging ethical issues with regards to the use of animals in the early stages of drug discovery for anti-inflammatory and degenerative diseases from natural products using the activity-directed isolation pathways when many compounds (eg > 100) are present in the crude extract or fraction and are to be tested The above-mentioned is the main reason for proposing the use of the in vitro anti-denaturation (stabilization) effects of heat treated (immunogenic) bovine serum albumin (BSA) as an assay. Current methods used for detecting and isolating a wide range of anti-inflammatory compounds in the early stages of the drug discovery process utilize a large number of animals. When BSA is heated and is undergoing denaturation, it expresses antigens associated to Type III hypersensitive reaction and which are related to diseases such as serum sickness, glomerulonephritis, rheumatoid arthritis and systemic lupus erythematosus. Thus, the assay that is being proposed should be applicable to the discovery of drugs for treating the above mentioned diseases and others, once the compounds stabilize the denaturation process.