RESUMEN
After incubation of both serum and HSA solutions with radioactive lanthanide complexes the binding constants of the corresponding lanthanide-protein complexes formed in the protein solutions under physiologic conditions, pH: 7.4, temperature: 310 K, isotonic ionic strength: 0.15 mol/L, were determined. The association constants of the lanthanide-protein complexes formed both in serum and HSA-solutions are equal within the experimental error. In conclusion, serum albumin binding predominates for the radiolanthanides. With the decrease of the ionic radii from 1.034 A (Ce) to 0.858 (Yb) the association constants increased by five orders of magnitude from 1 g Kpr = 4.90 (Ce) to 1 g Kpr = 9.54 (Yb). Further, a serum fractionation with alcohol was carried out to prove that the albumin fraction of serum is responsible for the lanthanide binding in blood.
Asunto(s)
Proteínas Sanguíneas , Metales de Tierras Raras , Albúmina Sérica , Estabilidad de Medicamentos , Humanos , Unión ProteicaRESUMEN
TcO-4 is reduced by a mixture of phosphine and thiol ligands to yield cationic complexes in which both ligands are coordinated. Polar and lipophilic properties of the products can easily be controlled by variation of either of the ligands. The yields are always high. Potential heart affinity of the compounds was screened by means of the isolated perfused rat heart. Some of the complexes show significant heart uptake and good retention in the myocardial tissue.
Asunto(s)
Corazón/diagnóstico por imagen , Compuestos Organofosforados/síntesis química , Pertecnetato de Sodio Tc 99m/síntesis química , Compuestos de Sulfhidrilo/síntesis química , Animales , Humanos , Técnicas In Vitro , Miocardio/metabolismo , Compuestos Organofosforados/farmacocinética , Cintigrafía , Ratas , Pertecnetato de Sodio Tc 99m/farmacocinética , Compuestos de Sulfhidrilo/farmacocinéticaAsunto(s)
Miocardio/metabolismo , Compuestos de Organotecnecio , Fosfinas/metabolismo , Tecnecio/metabolismo , Animales , Semivida , Cinética , Masculino , Ratas , Ratas Endogámicas , Porcinos , Distribución TisularRESUMEN
The preparation of [99mTc(1,2-bis(dimethylphosphino)ethane)2Cl2]+ ([99mTc(DMPE)2Cl2]+) for imaging the myocardium is investigated. Starting from Fe(III)- or Fe(II)-DMPE and 99mTcO4- different preparation variants are compared. In these reactions either ascorbic acid or DTPA serves as an agent for complexing iron. A simple procedure using lyophilized initial components is represented. Its application yields [99mTc(DMPE)2Cl2]+ with a radiochemical purity of more than 95%. Organ distribution studies performed in rats emphasize the high myocardial accumulation of this preparation.
Asunto(s)
Hierro , Marcaje Isotópico , Compuestos Organometálicos , Compuestos de Organotecnecio , Fosfinas , Tecnecio , Animales , Corazón/diagnóstico por imagen , Concentración de Iones de Hidrógeno , Fosfinas/metabolismo , Cintigrafía , Ratas , Ratas Endogámicas , Tecnecio/metabolismo , Distribución TisularRESUMEN
A modified method is described for the preparation of albumin nanospheres for labelling with 99mTc by investigating the absorption behaviour of tin as a reducing agent on albumin nanospheres. These albumin nanospheres can be used for studying the reticuloendothelial system, especially that of the liver. The labelling method is very simple, and the efficiency of labelling with 99mTc is higher than 97 per cent.
Asunto(s)
Composición de Medicamentos/métodos , Hígado/diagnóstico por imagen , Agregado de Albúmina Marcado con Tecnecio Tc 99m/aislamiento & purificación , Compuestos de Estaño , Estaño , Absorción , Química Farmacéutica , Humanos , Microesferas , Oxidación-Reducción , Cintigrafía , Albúmina Sérica , Pertecnetato de Sodio Tc 99mRESUMEN
The labeling of cysteine and its derivatives (penicillamine, N-acetylcysteine, cysteine ethyl ester) with 99Tc (99mTc) was studied as a model for the radiopharmaceutical preparation of Tc-99m mercaptide complexes. After the use of TcO4-, TcOCl52-, and TcBr62- as labeling agents for the Tc oxidation states VII, V, and IV, respectively, complexes of Tc(V) and Tc(IV) were prepared and characterized. The biologic behavior of these complexes was studied in rats. The substitutions in cysteine are responsible for substantial changes of net charge and lipophilicity in the Tc complexes, and the consequences on the excretion patterns in Wistar rats are discussed.