<abstract xmlns="http://www.w3.org/1999/xhtml"> This paper is an report of the investigation of the in vitro binding of 99mTc-DPD for synthetic amyloid fibrils used for the diagnosis of cardiac amyloidosis (CA), as compared with the use of 99mTc-HMDP and 99mTc-PPI. It also includes an inquiry into the role played by Ca2+ ions and serum proteins on binding to amyloid like materials, as well as the saturability and specificity of DPD for fibrils versus amorphous precipitates (AP). In the work, synthetic insulin fibrils (SIF) and AP were characterized by Congo red staining and TEM imaging. An equal amount of three radiopharmaceuticals were then added to fibrils in Ca2+ (0-4.2 mmol/L) or human serum (HS) adjoined samples and radiopharmaceutical uptake was assessed. To test the saturability of amyloid binding sites, a displacement assays with cold DPD was performed, while adding 50-1500 nmol of 99mTc-DPD to SIF or AP, saturation binding tests were subsequently carried out for evaluating its specificity for amyloid. Herein, synthetic fibrils and AP showed conformational differences at TEM and polarized microscopy analysis. In our study, 99mTc-DPD fibrils uptake was seen to be the highest and increased with calcium ions concentration. What is more, serum proteins reduced the bound fraction to the amyloid deposits of about 15%, and the Kd values of 90 nM and 114 nM relative to SIF and AP, respectively, did not significantly differ. We saw that 99mTc-DPD is the best seeker for amyloid fibrils in cardiac amyloidosis, and that Ca2+ concentration positively influenced DPD fibrils binding. Furthermore, the radioactivity bound to the serum protein clear up the idea of nuclide exchanging dynamic balance between amyloid and circulating proteins. Moreover, non-labeled DPD did not exert a competition for 99mTc-DPD binding sites, and, finally, DPD cannot be defined a radiopharmaceutical specific for amyloid deposits.</abstract>

This paper is an report of the investigation of the in vitro binding of 99mTc-DPD for synthetic amyloid fibrils used for the diagnosis of cardiac amyloidosis (CA), as compared with the use of 99mTc-HMDP and 99mTc-PPI. It also includes an inquiry into the role played by Ca2+ ions and serum proteins on binding to amyloid like materials, as well as the saturability and specificity of DPD for fibrils versus amorphous precipitates (AP). In the work, synthetic insulin fibrils (SIF) and AP were characterized by Congo red staining and TEM imaging. An equal amount of three radiopharmaceuticals were then added to fibrils in Ca2+ (0-4.2 mmol/L) or human serum (HS) adjoined samples and radiopharmaceutical uptake was assessed. To test the saturability of amyloid binding sites, a displacement assays with cold DPD was performed, while adding 50-1500 nmol of 99mTc-DPD to SIF or AP, saturation binding tests were subsequently carried out for evaluating its specificity for amyloid. Herein, synthetic fibrils and AP showed conformational differences at TEM and polarized microscopy analysis. In our study, 99mTc-DPD fibrils uptake was seen to be the highest and increased with calcium ions concentration. What is more, serum proteins reduced the bound fraction to the amyloid deposits of about 15%, and the Kd values of 90 nM and 114 nM relative to SIF and AP, respectively, did not significantly differ. We saw that 99mTc-DPD is the best seeker for amyloid fibrils in cardiac amyloidosis, and that Ca2+ concentration positively influenced DPD fibrils binding. Furthermore, the radioactivity bound to the serum protein clear up the idea of nuclide exchanging dynamic balance between amyloid and circulating proteins. Moreover, non-labeled DPD did not exert a competition for 99mTc-DPD binding sites, and, finally, DPD cannot be defined a radiopharmaceutical specific for amyloid deposits.

In vitro study: binding of 99mTc-DPD to synthetic amyloid fibrils

Department of Oncohaematology, Nuclear Medicine Unit, IRCCS San Matteo Hospital Foundation, V.le Golgi 19, 27100, Pavia, Italy

Center for Inherited Cardiovascular Diseases, IRCCS San Matteo Hospital Foundation, V.le Golgi 19, 27100, Pavia, Italy

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In vitro study: binding of Tc-DPD to synthetic amyloid fibrils

This paper is an report of the investigation of the in vitro binding of 99mTc-DPD for synthetic amyloid fibrils used for the diagnosis of cardiac amyloidosis...

In vitro study: binding of ^99mTc-DPD to synthetic amyloid fibrils

Publicado en línea: 30 dic 2015

Páginas: 231 - 235

Recibido: 22 jun 2015

Aceptado: 23 oct 2015

DOI: https://doi.org/10.1515/cipms-2015-0077

Palabras clave
nuclear medicine imaging, cardiac amyloidosis, 99mTc-diphosphonates, amyloid synthetic fibrils

© 2016

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

In vitro study: binding of 99mTc-DPD to synthetic amyloid fibrils

Publicado en línea: 30 dic 2015

Páginas: 231 - 235

Recibido: 22 jun 2015

Aceptado: 23 oct 2015

DOI: https://doi.org/10.1515/cipms-2015-0077

Palabras clavenuclear medicine imaging, cardiac amyloidosis, 99mTc-diphosphonates, amyloid synthetic fibrils

© 2016

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

In vitro study: binding of ^99mTc-DPD to synthetic amyloid fibrils

Palabras clave
nuclear medicine imaging, cardiac amyloidosis, 99mTc-diphosphonates, amyloid synthetic fibrils