RESUMEN
One restriction to the development and application of transcatheter arterial chemoembolization (TACE) therapy is the lack of an inherently radiopaque embolic whose location and distribution can be precisely visualized in real time and be used for non-invasive examination after surgery. Methods: A one-step electrospray method was developed to fabricate calcium alginate microspheres loaded with tantalum nanoparticles (Ta@CaAlg). The parameters of electrospraying were assessed. The in vivo X-ray imaging capability and embolic effect of Ta@CaAlg microspheres were evaluated in the renal arteries of normal rabbits by digital radiography and computed tomography. Doxorubicin hydrochloride (Dox) was chosen as a model drug, and the drug loading capacity and release behavior of these microspheres was valuated in vitro.Results: Spherical Ta@CaAlg microspheres with monodisperse sizes ranging from 150 to 1200 µm were fabricated by electrospraying. The results of an in vivo study showed that Ta@CaAlg microspheres possessed the qualities of both embolic agents and contrast media. They could not only feed back the real-time location and distribution of the embolic microspheres but also maintained clear X-ray imaging of embolized sites for up to 4 weeks as assessed by digital radiography and computed tomography. Digital subtraction angiography showed that they had an excellent embolic effect. Ta@CaAlg microspheres could be loaded with Dox to form "3-in-1" embolic microspheres. The maximum Dox loading was 97.3 mg Dox per mL beads and loaded microspheres exhibited pH-dependent release profiles. Conclusion: The X-ray opacity and drug-loading capability of Ta@CaAlg microspheres offers great promise in direct, real-time, in vivo investigation for TACE and long-term non-invasive re-examination.
Asunto(s)
Alginatos/farmacocinética , Antineoplásicos/farmacocinética , Carcinoma Hepatocelular/terapia , Doxorrubicina/farmacocinética , Neoplasias Hepáticas/terapia , Nanopartículas/química , Tantalio/farmacocinética , Alginatos/química , Animales , Antineoplásicos/química , Carcinoma Hepatocelular/diagnóstico por imagen , Medios de Contraste , Doxorrubicina/química , Portadores de Fármacos , Neoplasias Hepáticas/diagnóstico por imagen , Microesferas , Conejos , Radiografía , Tantalio/química , Tomografía Computarizada por Rayos XRESUMEN
This paper reviews biokinetic data for the Group VB elements vanadium, niobium, and tantalum, and presents biokinetic models describing their systemic behaviour. The model for systemic niobium in adults was developed earlier and described in Publication 134 of the International Commission on Radiological Protection. The model for niobium is used as a starting point for the development of models for vanadium and tantalum. Published biokinetic data for vanadium, including comparisons with niobium, indicate that the initial distribution of vanadium is broadly similar to that of niobium but that vanadium is less firmly fixed in most tissues and is excreted more rapidly than niobium. Biokinetic data for tantalum are more limited but suggest that its systemic behaviour closely resembles that of niobium at early times after administration. The model for niobium is proposed for application to tantalum in view of the suggested biological similarities of tantalum and niobium, their generally strong coherence in nature due to similar ionic radii and identical valence states, and the difficulties in developing parameter values directly from available data for tantalum. The proposed model for vanadium relies largely on vanadium-specific information and varies considerably from the model for niobium.
Asunto(s)
Modelos Biológicos , Niobio/farmacocinética , Tantalio/farmacocinética , Vanadio/farmacocinética , Adulto , Humanos , Cinética , Masculino , RadiometríaRESUMEN
OBJECTIVE: The aim of this study was to determine the potential of different high-Z elements to act as contrast media (CMs) alongside iodine (I) in dual-CM, dual-energy (DE) computed tomography examinations. METHODS: Gadolinium (Gd), tantalum (Ta), wolfram (W), gold (Au), and bismuth (Bi) in addition to I were examined at all available kilovolt settings in a DE computed tomography scanner. Dual-energy ratios were calculated by dividing attenuation at low kilovolt by attenuation at high kilovolt. Dual-energy data sets were loaded into material decomposition software to evaluate separation of the elements from I. RESULTS: The DE ratios of Ta, W, and Au ranged between 0.9 and 1.2, being considerably lower than I at 1.9 to 2.6. These elements were completely separated from I using material decomposition. Gadolinium and Bi were more similar to I at 1.4 to 1.9. However, separation was nearly complete for Bi and suboptimal for Gd. CONCLUSIONS: Tantalum, W, and Au are ideal candidates for dual-CM examinations, whereas Bi is a slightly weaker candidate.
Asunto(s)
Medios de Contraste/farmacocinética , Aumento de la Imagen , Yodo/farmacocinética , Metales Pesados/farmacocinética , Tomografía Computarizada por Rayos X , Bismuto/farmacocinética , Gadolinio/farmacocinética , Oro/farmacocinética , Fantasmas de Imagen , Interpretación de Imagen Radiográfica Asistida por Computador , Tantalio/farmacocinética , Tungsteno/farmacocinéticaRESUMEN
Tantalum oxide nanoparticles show great potential as the next generation of X-ray contrast media. Recently, we reported advances in tantalum oxide nanoparticles and identified improvements that were required for such particles to progress further. Namely, the viscosity of concentrated particles, the amount of retention in reticuloendothelial (RES) tissues, and the effect of large quantities of particles on the kidneys after administration were all identified as critical factors which needed further study, understanding, and development. Here, we report on a zwitterionic siloxane polymer nanoparticle coating that reduced the viscosity of concentrated solutions of particles by a factor of 5, decreased tissue retention of injected particles by a factor of 10, and, importantly, did not induce pathological responses in the kidneys.
Asunto(s)
Nanocápsulas/química , Óxidos/farmacocinética , Siloxanos/química , Tantalio/farmacocinética , Tomografía Computarizada por Rayos X/métodos , Animales , Medios de Contraste/efectos adversos , Medios de Contraste/síntesis química , Riñón/efectos de los fármacos , Ensayo de Materiales , Tasa de Depuración Metabólica , Nanocápsulas/efectos adversos , Especificidad de Órganos , Óxidos/efectos adversos , Tamaño de la Partícula , Ratas , Tantalio/efectos adversos , Distribución TisularRESUMEN
An accidental tantalum powder deflagration with casualties occurred during the operation of a bag filter dust-collecting device. To understand the mechanism of the incident and its material hazards, experiments for determining the combustibility and ignition characteristics of the tantalum powder were performed. The magnitude of the tantalum dust explosion is classified as severe (K(st)=273), contrary to the classification found in the preceding literature. The minimum ignition energies for both a dust cloud and a dust layer of the tantalum powder were also found to be far lower than previous values. Judging from the observation of the surface with an SEM, the coral-like structure of each particle of the tantalum powder can enhance its fire and explosion hazards and affect its sensitivity to electrostatic sparks by increasing in particle surface area. A thin, non-conductive oxide layer of the tantalum powder surface has a high resistivity and generates electrostatic charge when rubbed with conductive materials like the wall of the collecting device. The authors conclude that the possible cause of the ignition was electrostatic discharge resulting from charging electrostatically.
Asunto(s)
Falla de Equipo , Explosiones , Tantalio/química , Accidentes de Trabajo , Polvo , Filtración , Humanos , Tantalio/farmacocinéticaRESUMEN
The biodistribution and binding substances of 95Nb and 182Ta were investigated and compared with other nuclides using tumor-bearing rats and mice. Retention values of 95Nb in tumor tissue were greater than those for 67Ga-citrate, while those for 182Ta were similar to those for 67Ga. The values for these nuclides in the liver and spleen were much smaller than those for 67Ga. However, the values for blood and some soft tissues were much greater than those for 67Ga. The concentrations of 95Nb and 182Ta were more dominant in the connective tissue (especially inflammatory tissue) than in the other categories of tumor tissue. These nuclides accumulated rapidly into the mitochondrial fraction (containing lysosome) of the liver, reaching about 50% after 48 hours, but these nuclides existed relatively uniformly in the tumor cells. The main binding substance of these nuclides in the above tissues was the acid mucopolysaccharide whose molecular mass exceeded 40,000 daltons. Radioactive niobium can be a potential tumor imaging agent. Among radioactive niobiums, 95mNb has physical characteristics (half-life 90 hours, IT decay, 234-keV energy of 100% abundance) suitable for clinical imaging study.
Asunto(s)
Hígado/metabolismo , Neoplasias Experimentales/metabolismo , Niobio/farmacocinética , Tantalio/farmacocinética , Animales , Masculino , Ratones , Mitocondrias Hepáticas/metabolismo , Radioisótopos/farmacocinética , Distribución TisularRESUMEN
Distribution in the organism of the tantalum after its application on the brain surgical wound was studied by light microscopy and atomic-emission spectrum analysis with an induction-linked plasma in patients dying from neuro oncological diseases. It is found that in all cases a partial tantalum migration into various brain regions and internal organs occurs. Blood cells are able to fix the tantalum particles in vivo and in vitro, this process being enhanced after a preceding angiography.