RESUMO
In the past decades new imaging techniques and developments in existing systems have been introduced. Novel ideas with strong potential in areas such as radiography, nuclear magnetic resonance, ultrasound and nuclear medicine have recently emerged or are still under development or evaluation. Positron emission tomography (PET) is finally garnering enormous interest for high-sensitivity and high-specificity molecular imaging. The combination of PET and computed tomography is proving to be very useful in clinical oncology. Functional magnetic resonance imaging and magnetic resonance spectroscopy are also emerging as strong partners in terms of functional information. Recent improvements in ultrasound imaging, such as a 3-D, tissue harmonics, high-frequency, real time, extended field of view and new contrast agents, show the potential of this methodology. Film/screen mammography represents the ultimate in radiography capacities, but new digital systems are beginning to offer even better response.
Assuntos
Diagnóstico por Imagem/tendências , Aumento da Imagem/instrumentação , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/instrumentação , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/tendências , Medicina Nuclear/tendências , Diagnóstico por Imagem/instrumentação , Diagnóstico por Imagem/métodos , Previsões , Medicina Nuclear/instrumentação , Medicina Nuclear/métodos , Processamento de Sinais Assistido por ComputadorRESUMO
The detection of sialic acid in living systems is of importance for the diagnosis of several types of malignancy. We have designed and synthesized two new lanthanide ion ligands (L1 and L2) that are capable of molecular recognition of sialic acid residues. The basic structure of these ligands consists of a DTPA-bisamide (DTPA, diethylenetriamine pentaacetic acid) whose amide moieties each bear both a boronic function for interaction with the diol groups in the side chain of sialic acid, and a functional group that is positively charged at physiologic pH values and is designed to interact with the carboxylate anion of sialic acid. The relaxometric properties of the Gd3+ complexes of these two ligands were evaluated. The relaxivity of the GdL1 complex has a significant second-sphere contribution at pH values above the pKa of its phenylboronic acid moiety. The interaction of the Gd3+ complexes of L1 and L2 with each of several saccharides was investigated by means of a competitive fluorescent assay. The results show that both complexes recognize sialic acid with good selectivity in the presence of other sugars. The adduct formed by GdL2 with sialic acid has the higher conditional formation constant (50.43+/-4.61 M(-1) at pH 7.4). The ability of such complexes to recognize sialic acid was confirmed by the results of a study on the interaction of corresponding radiolabeled complexes (153SmL1 and 153SmL2) with C6 glioma rat cells. 153SmL2 in particular is retained on the cell surface in significant amounts.
Assuntos
Meios de Contraste/análise , Meios de Contraste/química , Imageamento por Ressonância Magnética/métodos , Ácido N-Acetilneuramínico/análise , Ácido N-Acetilneuramínico/química , Ácidos Borônicos/química , Carboidratos/química , Cátions/química , Gadolínio/química , Concentração de Íons de Hidrogênio , Ligantes , Estrutura Molecular , Ácido Pentético/química , Temperatura , Titulometria , ÁguaRESUMO
UNLABELLED: Lymphatic drainage plays an important role in the uptake of particulates in the respiratory system, being also associated to the spreading of lung cancer through metastasis development. In recent years solid lipid nanoparticles (SLN) have been proposed as carriers of anti-tumoural drugs, for their low toxicity and surface characteristics make them suitable for either imaging (gamma-scintigraphy) or therapy upon encapsulation of cytotoxic drugs. Assessment of inhaled radiolabelled SLN biodistribution is described in the present work. METHODS: Nanoparticles (200 nm) were radiolabelled with 99mTc using the lipophilic chelator D,L-hexamehylpropyleneamine oxime (HMPAO). Biodistribution studies were carried out following aerosolisation and administration of a 99mTc-HMPAO-SLN suspension to a group of adult male Wistar rats. A 60 min dynamic image acquisition was performed in a gamma-camera, followed by static image collection at 30 min intervals up to 4 h postinhalation. Radiation counting was performed in organ samples, collected after the animals were sacrificed. RESULTS: The data show an important and significant uptake of the radiolabelled SLN into the lymphatics after inhalation, and a high rate of distribution in periaortic, axillar and inguinal lymph nodes. CONCLUSION: Results indicate that SLN could be effective colloidal carriers for lymphoscintigraphy or therapy upon pulmonary delivery.
