Summary Pretargeting techniques using the avidin-biotin system have shown encouraging results in both diagnostic and therapeutic clinical trials. It has been shown that in cancer therapy the ideal agent to be used for pretargeting should have a plasma half-life longer than avidin and lower immunogenicity than streptavidin in order for these procedures to be applied safely and repeatedly in patients. We prepared a recombinant form of avidin with no carbohydrates and avidins, biochemically modified either by decreasing the positive charges with succinic anhydride or by linking polyethylene glycol (PEG) at three different molar ratios and evaluated their in vivo behaviour after i.p. administration in mice. The succinylation and PEGylation of avidin increased the plasma half-life proportionally to the degree of protein modification. The procedures, however, affected the biotin binding to some extent. The biodistribution studies showed that, for all six time points (ranging from 20 min to 18 h post-injection), the liver and kidney to blood ratios were lower for PEGylated avidins than native, recombinant and succinyl avidin. Recombinant and low PEGylated avidin evoked an immune response in all mice after at least three injections. Native, recombinant and succinyl avidins showed higher serum titres than PEGylated avidins. In conclusion, the conjugation of avidin to PEG chains (n = 7) originates a compound with a suitable blood clearance, low immunogenicity and concurrent low cross-reactivity with avidin.
La agenesia unilateral de la arteria pulmonar es una malformación poco frecuente, en ocasiones asintomática y subdiagnosticada. La agenesia derecha suele ser aislada, en cambio la izquierda se asocia más frecuentemente a malformaciones cardiovasculares. Algunos pacientes presentan infecciones respiratorias recurrentes, limitación al ejercicio, hemoptisis y/o hipertensión pulmonar. El diagnóstico se sospecha al solicitar una radiografía de tórax que muestra un pulmón hipoplásico ipsilateral a la agenesia. Se confirma con tomografía computada de tórax con contraste. En pacientes asintomáticos el manejo debe ser conservador, sin embargo, se debe iniciar la búsqueda de vasos colaterales especialmente durante la adolescencia, los que pueden sangrar. En cambio, en los pacientes sintomáticos o que presentan complicaciones graves, el tratamiento debe ser intervencional. El objetivo de este trabajo es presentar a dos pacientes con agenesia de la arteria pulmonar derecha e izquierda respectivamente y hacer una revisión de la literatura.
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