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Borgognoni C.F.,University of Sao Paulo | Maizato M.J.S.,University of Sao Paulo | Leirner A.A.,University of Sao Paulo | Polakiewicz B.,University of Sao Paulo | And 3 more authors.
Journal of Applied Biomaterials and Biomechanics | Year: 2010

Purpose: Biomaterials have been widely used in the field of regenerative medicine. Bovine pericardium tissue has been successfully used as a bioprosthetic material in manufacturing heart valves, but studies concerning the tissue are ongoing in order to improve its storage, preservation and transportation. This article provides an overview of the characteristics of bovine pericardium tissue chemically treated after the freeze-drying process. these characteristics are essential to evaluate the changes or damage to the tissue during the process. Methods: The mechanical properties of the tissue were analyzed by three different methods due to its anisotropic characteristics. The physical properties were analyzed by a colorimetric method, while the morphological properties were evaluated by scanning electron microscopy (SEM). Results: The freeze-dried bovine pericardium showed no significant change in its mechanical properties. There was no significant change in the elasticity of the tissue (p>0.05) and no color change. In addition, SEM analysis showed that the freeze-dried samples did not suffer structural collapse. Conclusions: It was concluded that glutaraldehyde-treated bovine pericardium tissue showed no significant change in its properties after the freeze-drying process. © 2010 Società Italiana Biomateriali.

Galante A.M.S.,Institute of Energetic and Nuclear Research | Galante O.L.,Av. Torres de Oliveira | Camposa L.L.,Institute of Energetic and Nuclear Research
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

Changes induced by radiation in the UV-vis and Infrared absorbance spectra of fluoropolymer films were investigated. Samples (3 × 1 cm 2) of commercially available fluoropolymers, tetrafluoropolymer homopolymer (PTFE-Tecnofluor/DuPont) and its copolymers with hexafluoropropylene (FEP 1000 C-DuPont) and perfluoroalkoxy (PFA 500 CLP-Dupont) were irradiated with 60Co gamma radiation in free air at electronic equilibrium conditions with absorbed doses between 1 and 150kGy. Studies of environmental condition effects, such as temperature and light, pre- and post-irradiation stability and dose range useful response were carried out. Fluoropolymers are very stable when exposed to different ambient conditions; the dosimetric wavelength is characteristic for each type of fluoropolymer and a linear correlation was found between gamma radiation dose and optical response. © 2009 Elsevier B.V.

Fernandez Nunez E.G.,Institute of Energetic and Nuclear Research | Linkowski Faintuch B.,Institute of Energetic and Nuclear Research | Teodoro R.,Institute of Energetic and Nuclear Research | Pereira Wiecek D.,Institute of Energetic and Nuclear Research | And 7 more authors.
Applied Radiation and Isotopes | Year: 2011

The objective of this study was the development of a statistical approach for radiolabeling optimization of cysteine-dextran conjugates with Tc-99m tricarbonyl core. This strategy has been applied to the labeling of 2-propylene-S-cysteine-dextran in the attempt to prepare a new class of tracers for sentinel lymph node detection, and can be extended to other radiopharmaceuticals for different targets. The statistical routine was based on three-level factorial design. Best labeling conditions were achieved. The specific activity reached was 5. MBq/γg. © 2011.

Nunez E.G.F.,Institute of Energetic and Nuclear Research | Teodoro R.,Institute of Energetic and Nuclear Research | Wiecek D.P.,Institute of Energetic and Nuclear Research | Da Silva N.G.,Institute of Energetic and Nuclear Research | And 2 more authors.
Acta Radiologica | Year: 2011

Background: Biological performance of radiotracers for sentinel node detection analyzed in the light of molecular design and dimension is not widely available. Purpose: To evaluate the effect of dextran molecular size and the presence of tissue-binding units (mannose) within the model of 99mTc-carbonyl conjugate for sentinel lymph node detection. Material and Methods: Four dextran conjugates with and without mannose in the chemical backbone were included. All polymers were radiolabeled using the precursor [99mTc(OH2)3(CO)3]+. Radiolabeling conditions targeted the best radiochemical purity and specific activity for each radiopharmaceutical, and partition coefficients were also defined. Lymphoscintigraphy and ex-vivo biodistribution in popliteal lymph node, liver and kidneys were performed in Wistar rats. The effects of molecular weight and mannose presence were assessed by a two-level factorial design. Results: Radiochemical purity was indirectly related to molecular weight and presence of mannose in the polymer structure. All products were able to detect popliteal lymph node, however, uptake was strongly influenced by use of mannose (4-fold higher). Excretion was similarly modulated by differences in molecular weight. Mannose-enhanced lymph node uptake and higher molecule size in the range under study benefitted lymphoscintigraphic performance. Conclusion: Screening of radiopharmaceuticals for lymphoscintigraphy might improve with attention to the mentioned physico-chemical features of the molecule.

Oliveira E.A.,Institute of Energetic and Nuclear Research | Faintuch B.L.,Institute of Energetic and Nuclear Research | Nunez E.G.F.,Institute of Energetic and Nuclear Research | Maria Moro A.,Butantan Institute | And 2 more authors.
Melanoma Research | Year: 2012

Early and reliable diagnosis of melanoma, a skin tumor with a poor prognosis, is extremely important. Phage display peptide libraries are a convenient screening resource for identifying bioactive peptides that interact with cancer targets. The aim of this study was to evaluate two technetium-99m tracers for angiogenesis detection in a melanoma model, using cyclic pegylated pentapeptide with RGD and NGR motifs conjugated with the bifunctional chelator mercaptoacetyltriglycine (MAG 3). The conjugated peptides (10 μl of a μg/μl solution) were labeled with technetium-99m using a sodium tartrate buffer. Radiochemical evaluation was carried out by instant thin-layer chromatography and confirmed by high-performance liquid chromatography. The partition coefficient was determined and internalization assays were performed in two melanoma cell lines (B16F10 and SKMEL28). Biodistribution evaluation of the tracers was carried out in healthy animals at different time points and also in tumor-bearing mice, 120 min post injection. Blocking studies were also conducted by coinjection of cold peptides. The conjugates displayed a rather similar pharmacokinetic profile. They were radiolabeled with high radiochemical purity (>97%) and both were hydrophilic with preferential renal excretion. Yet, tumor uptake was higher for human than for murine melanoma cells, especially for [ 99mTc]-MAG 3-PEG 8-c(RGDyk) (7.85±2.34%injected dose/g 120 min post injection). The performance of [ 99nTc]-MAG 3-PEG 8-c(RGDyk) was better than the NGR tracer with regard to human melanoma uptake. In this sense, it should be considered for future radiotracer studies of tumor diagnosis. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

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