LUIS ALBERTO PEREIRA DIAS

LUIS ALBERTO PEREIRA DIAS

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Specific methodology to analyse the activity meters performance inside the hot cell
2024 - MARTINS, ELAINE W.; POTIENS, MARIA da P.A.; DIAS, LUIS A.P.
Introduction: The Instrument Calibration Laboratory (LCI) at IPEN responsible for developing andimplementing calibration methodologies for various types of instruments used in the nuclear field andrelated areas. Its main responsibilities include conducting precise and traceable calibrations to ensure theaccuracy and reliability of equipment, such as activimeters used in nuclear medicine services (NMS).Additionally, LCI promotes the continuous development of new calibration methodologies, including “insitu” approaches that allow instruments to be calibrated at their actual point of use. It also maintainsstandards and procedures to ensure that measurements performed are comparable and traceable tointernational standards. LCI provides specialized support to critical sectors such as nuclear medicine,where accurate measurements of radioactivity are essential for safe and effective diagnostics andtreatments. It collaborates with research institutions, universities, and industries, offering calibrationservices to both the public and private sectors. The National Commission of Nuclear Energy establishesthat each nuclear medicine service have at least one activimeter, under a periodic testing as a part of aquality program to ensure reliable results. Calibration factors must be traceable for each radionuclide, asinaccurate measurements can introduce uncertainties that directly affect diagnostics and therapies.Activimeters, crucial in these practices, are often located in controlled and hard-to-access areas,complicating both their handling and transport to specialized laboratories for calibration. To address thischallenge, LCI has developed in situ calibration methodologies where the radiopharmaceutical itselfserves as the reference source. Objective: This study aimed to develop and implement a methodology for the control and calibration ofactivimeters using radionuclides produced by the Radiopharmaceutical Production Center at IPEN. Themethodology simplifies the procedure by transporting only the radioactive samples, without the need tomove the activimeter itself, thereby preserving the quality and accuracy of measurements. Materials and Methods: Since the development of the new methodology and the execution of this work,all steps for calibrating activimeters have been based on the methodology applied at the National PhysicalLaboratory (NPL), UK. Eleven activimeters from the Radiopharmaceutical Production Sector of IPENwere tested using radionuclides 99mTc, 123I, 131I, 111In, and 67Ga. Calibration factors were determined foreach dose activimeter. Results and Conclusions: After applying the methodology by qualified technicians, the results obtainedfrom the tested activimeters demonstrated their significance, as calibration factors could show correctionsof up to 5% for each tested radionuclide.
Preliminary study of sterilizing filtration validation
2024 - OLIVEIRA, V.L.T.; SANTOS, L.J.; CAVALCANTE, L.C.; DIAS, L.A.P.; FELGUEIRAS, C.F.; MATSUDA, M.M.N.
Development of glycan‑targeted nanoparticles as a novel therapeutic opportunity for gastric cancer treatment
2023 - SANTOS, SOFIA N. dos; GUSHIKEN JUNIOR, DINO S.; PEREIRA, JHONATAS P.M.; IADOCICCO, NATALIA M.; SILVA, ANDRE H.; NASCIMENTO, TATIELLE do; DIAS, LUIS A.P.; SILVA, FLAVIA R. de O.; RICCI-JUNIOR, EDUARDO; SANTOS-OLIVEIRA, RALPH; BERNARDES, EMERSON S.
Chemotherapy resistance remains a major cause of therapeutic failure in gastric cancer. The combination of genetic material such as interference RNAs (iRNAs) to silence cancer-associated genes with chemotherapeutics has become a novel approach for cancer treatment. However, finding the right target genes and developing non-toxic, highly selective nanocarrier systems remains a challenge. Here we developed a novel sialyl-Tn-targeted polylactic acid—didodecyldimethylammonium bromide nanoparticle (PLA-DDAB) nanoparticles (NPs) loaded with dsRNA targeting ST6GalNac-I and/or galectin-3 genes. Using single photon emission computed tomography (SPECT), we have demonstrated that 99mtechnetium radiolabeled sialyl-Tn-targeted nanoparticles can reach the tumor site and downregulate ST6GalNAc-I and galectin-3 RNA expression levels when injected intravenously. Furthermore, using an in vivo gastric tumor model, these nanoparticles increased the effectiveness of 5-FU in reducing tumor growth. Our findings indicate that cancer-associated glycan-targeted NPs loaded with dsRNA targeting ST6GalNAc-I and/or galectin-3 in combination with standard chemotherapy, have the potential to become a novel therapeutic tool for gastric cancer.
In vitro and in vivo response of PSMA-617 radiolabeled with CA and NCA lutetium-177
2022 - BOAS, CRISTIAN A.W.V.; SILVA, JEFFERSON de J.; DIAS, LUIS A.P.; FREIRE, MARIA R.B.; BALIEIRO, LUIZA M.; SANTOS, CAROLINA S.F. dos; VIVALDINI, BIANCA F.; BENEDETTO, RAQUEL; VIEIRA, DANIEL P.; PASSOS, PRISCILA de Q.S.; MARUMO, MARIA H.; TEIXEIRA, LUIS F.S.; ARAUJO, ELAINE B. de
The PSMA-targeted radionuclide therapy has been explored since 2015 with radioisotope lutetium-177, whose β− emission range is adequate for micrometastases treatment. This radioisotope is obtained by two different production routes that directly affect the specific activity of lutetium-177 (non-carrier added and carrier added) and, consequently, the specific activity of radiopharmaceuticals, like 177Lu-PSMA-617. The influence of the specific activity of lutetium-177 on the properties of the radiopharmaceutical PSMA-617 was evaluated through pre-clinical studies. The in vitro study pointed to a lower constant of dissociation with non-carrier added lutetium-177 due to the difference in the specific activity. However, competition and internalization assays resulted in similar results for both lutetium-177. Based on these pre-clinical experiments, the total in vitro tumor cell binding and tumor uptake in vivo were similar, with no influence of the specific activity of the 177Lu-PSMA-617. Regardless the specific activity did not directly affect tumor uptake, the tumor/non-target organs ratios were higher for the radiopharmaceutical labeled with carrier added lutetium-177, which had the lowest specific activity.
Stability in production and transport of 177Lu labeled PSMA
2021 - VILLAS BOAS, C.A.W.; DIAS, L.A.P.; MATSUDA, M.M.N.; ARAUJO, E.B.
In Brazil, prostate cancer is a common disease among men. The radionuclide therapy with PSMA analogs, labeled with beta and alpha emitters, has brought new perspectives for patients with multi metastatic resistant prostate cancer. The commercialization of radiopharmaceutical becomes a challenge to transport and ensure the quality of the product, especially in terms of radiochemical stability of therapeutic radiopharmaceuticals. The effect of radiolysis on therapeutic doses of radiopharmaceuticals can be avoided or mitigated by diluting the final dose and reducing storage and transportation temperature. This study evaluated the effect of radiolysis on the different radioactive concentration in the industrial batches of 177Lu-PSMA-617 and in the fractionated doses, considering long time transportation. The radiopharmaceutical 177Lu-PSMA-617 was produced in batches reaching 37 GBq, and stability studies were performed in controlled conditions. The results showed that a combination of factors, including reaction buffer, the radioactive concentration of final product, and freezing storage contributed to the stability of the radiopharmaceutical for 48 hours, enabling transport of 177Lu-PSMA-617 to distant regions of the country.