Analytical methods for assessing changes induced by gamma exposure in an animal model.

OBJECTIVE: Ionizing radiation can cause radio-induced changes in the cellular metabolome due to the breakdown of DNA bonds. Our goal was to find the early tissue response to radiation exposure supported by distinct analytical methods. METHODS: Histological analyses were performed on the organs extracted from rats to search for microscopic changes. The histological slides stained with hematoxyline-eosin (HE) were analyzed in magnification (40x). Subsequently, the tissues were subjected to mass spectrometry that allowed molecular analysis and DESI-MSI that generated the molecular image of lipids, assessing changes in intensities, especially in the brain. RESULTS: The histological analysis found nonspecific inflammatory changes; no areas of fibrosis, necrosis, or apoptosis were identified, suggesting non-morphological tissue alterations. However, the DESI-MSI images of brain lipids allowed the observation of many radio-induced changes in the lipid's intensities. CONCLUSIONS: No early radio induced histological or mass weight changes in the radiation exposed rats could be observed at 5 Gy. However, early changes in the molecular level were observed in the DESI-MSI images of the brain lipids. The DESI-MSI method proved to be efficient and relevant, allowing a regional molecular analysis of the tissues, expanding a new field of study that is still in its infancy: radiometabolomics.

Analytical methods for assessing changes induced by gamma exposure in an animal model

SUMMARY OBJECTIVE: Ionizing radiation can cause radio-induced changes in the cellular metabolome due to the breakdown of DNA bonds. Our goal was to find the early tissue response to radiation exposure supported by distinct analytical methods. METHODS: Histological analyses were performed on the organs extracted from rats to search for microscopic changes. The histological slides stained with hematoxyline-eosin (HE) were analyzed in magnification (40x). Subsequently, the tissues were subjected to mass spectrometry that allowed molecular analysis and DESI-MSI that generated the molecular image of lipids, assessing changes in intensities, especially in the brain. RESULTS: The histological analysis found nonspecific inflammatory changes; no areas of fibrosis, necrosis, or apoptosis were identified, suggesting non-morphological tissue alterations. However, the DESI-MSI images of brain lipids allowed the observation of many radio-induced changes in the lipid's intensities. CONCLUSIONS: No early radio induced histological or mass weight changes in the radiation exposed rats could be observed at 5 Gy. However, early changes in the molecular level were observed in the DESI-MSI images of the brain lipids. The DESI-MSI method proved to be efficient and relevant, allowing a regional molecular analysis of the tissues, expanding a new field of study that is still in its infancy: radiometabolomics.

RESUMO OBJETIVO: Radiação ionizante pode causar alterações no metaboloma celular devido à quebra de ligações no DNA. O objetivo deste trabalho foi evidenciar a resposta aguda tecidual induzida pela exposição da radiação ionizante. MÉTODOS: Análises histológicas foram realizadas nos órgãos extraídos de ratos para análise de alterações microscópicas. As lâminas histológicas coradas com hematoxilina eosina (HE) foram analisadas em aumento (40x). Posteriormente, os tecidos foram submetidos a espectrometria de massa, que permitiu análise molecular e o Desi-MSI que gerou imagem molecular de lipídios, identificando alterações na intensidade, principalmente no cérebro. RESULTADOS: As análises histológicas encontraram alterações inflamatórias inespecíficas, nem áreas de fibrose, necrose ou apoptose, sugerindo ausência de alterações morfológicas. As imagens de lipídios cerebrais obtidas por Desi-MSI permitiram observar as inúmeras alterações na intensidade nas seções teciduais do encéfalo. CONCLUSÕES: Alterações agudas radioinduzidas de massa do órgão e histológicas nos órgãos dos ratos expostos não puderam ser observadas a 5 Gy. Entretanto, mudanças em nível molecular foram observadas nas imagens de Desi-MSI dos lipídios cerebrais. O método Desi-MSI mostrou-se eficiente e relevante, permitindo a análise molecular regi-onal dos tecidos no SNC, expandindo um novo campo de estudo que ainda está em sua infância: a radiometaboloma.

Glucose-holmium for radiotherapy: Characterization and in vitro assays.

BACKGROUND: The existence of saccharide-holmium complexes, containing mono or polysaccharide molecules, is an attractive hypothesis toward a radiation therapy (RT) with beta-emitters targeting high glucose metabolic human sites. To exam such hypothesis, the aim of this study was to investigate the possible chemical interactions of Ho and glucose molecules and if glucose may be a facilitator to holmium cell internalization based on in vitro uptake assays and mass spectrometry analyses. METHODS: The ionic-solution preparations were based on glucose-anhydrous and holmium-nitrate hydrated in aqueous solution, in non-radioactive condition. The uptakes in MDAMB231 cell lineage were evaluated, at 0 and 50 µg mL-1 holmium solution, in incubation times of 10, 30 and 50 min. The measurements of the holmium mass into the dried cell were evaluated by Neutron Activation Analysis - NAA method. Also, the ionic solution was tested in Electrospray Ionization Mass Spectrometry (ESI-MS) in order to identify Ho and glucose interactions. RESULTS: There were intracellular holmium-uptake in MDAMB-231 of 3.6 ±â€¯0.1, 6.8 ±â€¯0.2 and 9.7 ±â€¯0.3 µg increasing linearly with incubation time. The m/z ions at 523, 586, 649, 991 and 1054 were attributed to the positively loaded species containing Ho+3, glucose (GLU) and NO3-, making up the possible molecular compound formulae, involving Ho, GLU, and anions. CONCLUSIONS: The findings of the in vitro assay and the ESI-MS suggested a suitable holmium cell uptake, increased in function of incubation time, due to the presence of glucose and holmium chemical interactions in solution.

Breastdosimetry of 99mTc-balloon in complementary radiotherapy.

Dose reinforcement in primary tumor cavity can complement conventional radiotherapy in patients with early breast cancer. In this study, a dosimetric analysis was conducted by pertechnetate-99mTc-filled balloon brachytherapy (TBB). METHODS: Dosimetry based on radiochromic films and on a computational voxel thorax model was performed. Calibration protocol achieved a mathematical relationship between dose and optical density in films placed on the surface at a distance of 0-9cm, 1cm between them, in which dose values were provided by MCNP® code. Moreover, experimental spatial dose distribution was prepared. A female thorax voxel model was developed in the SISCODES®/MCNP® codes. Additionally, experimental and computational doses at 8-10mm from balloon surface were compared. RESULTS: Dose from 99mTc-balloon, with 16mm diameter, 32.22GBq activity, and 24h exposure time, achieved 8.08±0.42 (Ue) and 8.82±1.76 (Ue) Gy, at a distance of 10mm from the balloon surface for the experimental data and computational modeling, respectively, thus showing nonsignificant difference. The spatial dose distribution in the chest wall, glandular tissue, breast skin, and lung was presented. The dosimetric findings supported the TBB modality presenting a suitable spatial dose distribution in the tumor bed and preserving the adjacent health tissues. CONCLUSION: TBB is a viable adjuvant brachytherapy modality for breast cancer in patients who have an appropriate indication.

Kinetics of the expressions of radiation-induced plasma proteins of the cardiac territory in electrophoresis / Cinética das expressões de proteínas plasmáticas radioinduzidas do território cardíaco em eletroforese

ABSTRACT Introduction: Radiation induces acute and late alterations in blood proteins. Objective: The present study aims at analyzing in time kinetics the electrophoretic profiles of expression bands of blood protein, in the molecular weight range greater than and equal to that of albumin, modulated by ionizing radiation in the cardiac territory, in animal model. Material and methods: Animals were exposed to a whole-body dose of 5 Gy ionizing radiation (Co-60). Serum samples were collected from isogenic Wistar rats (control and irradiated groups). At a time kinetics of 12, 24, 48, 72, 96 hours and 35 days post-irradiation, thoracolaparotomies were performed with anesthesia, and 0.3 ml of blood was collected between the left ventricle and the pulmonary artery. The samples were held in heparin and their components were separated by centrifugation. Protein bands with similar molecular weight were identified by vertical 10% electrophoresis, silver staining. Results: The findings indicate a systemic acute altered expression of proteins with molecular weight greater than or equal to that of albumin in acrylamide gel, presenting suppression and increased expression due to modulation of preexisting bands, identified in time kinetics. Conclusion: These findings point out to acute alterations of protein expression modulated in time, but also to a late modulation of gene expression.

RESUMO Introdução: A radiação de corpo inteiro induz alterações agudas e tardias no perfil proteico sanguíneo. Objetivo: O presente estudo tem como escopo analisar em cinética de tempo o perfil eletroforético de bandas de expressão das proteínas solúveis do sangue, na faixa de peso molecular superior e igual à albumina, moduladas por radiação ionizante no território cardíaco em modelo animal. Materiais e métodos: Animais foram expostos à radiação de Co-60, em dose de 5 Gy corpo inteiro. Foram coletadas amostras de soro sanguíneo em ratos Wistar isogênicos (no grupo-controle e no irradiado). Em uma cinética de tempo de 12, 24, 48, 72 e 96 horas e 35 dias pós-exposição, foram realizadas toracolaparotomias com anestesia profunda e, posteriormente, foi coletado 0,3 ml de sangue entre ventrículo esquerdo e artéria pulmonar. As amostras foram heparinizadas, sendo, em seguida, separados seus componentes por centrifugação. As bandas proteicas de peso molecular similar foram identificadas por eletroforese vertical a 10%, coradas com prata. Resultados: Os achados indicam alteração aguda sistêmica da expressão das proteínas de peso molecular superior ou igual à albumina em gel de acrilamida, representando supressão e aumento de expressões por meio da modulação de bandas preexistentes identificadas em cinética de tempo. Conclusão: Esses achados apontam tanto para uma alteração aguda modulada no tempo da expressão proteica quanto para uma alteração moderada tardia da expressão gênica.

Brain tumour and infiltrations dosimetry of boron neutron capture therapy combined with 252Cf brachytherapy.

This article presents a dosimetric investigation of boron neutron capture therapy (BNCT) combined with (252)Cf brachytherapy for brain tumour control. The study was conducted through computational simulation in MCNP5 code, using a precise and discrete voxel model of a human head, in which a hypothetical brain tumour was incorporated. A boron concentration ratio of 1:5 for healthy-tissue: tumour was considered. Absorbed and biologically weighted dose rates and neutron fluency in the voxel model were evaluated. The absorbed dose rate results were exported to SISCODES software, which generates the isodose surfaces on the brain. Analyses were performed to clarify the relevance of boron concentrations in occult infiltrations far from the target tumour, with boron concentration ratios of 1:1 up to 1:50 for healthy-tissue:infiltrations and healthy-tissue:tumour. The average biologically weighted dose rates at tumour area exceed up to 40 times the surrounding healthy tissue dose rates. In addition, the biologically weighted dose rates from boron have the main contribution at the infiltrations, especially far from primary tumour. In conclusion, BNCT combined with (252)Cf brachytherapy is an alternative technique for brain tumour treatment because it intensifies dose deposition at the tumour and at infiltrations, sparing healthy brain tissue.

Development of a voxel model of the heart for dosimetry.

This article investigates the dosimetry of a radioactive stent and radioactive liquid balloon placed into the heart vasculature to prevent restenosis after atherosclerosis treatment. The research aims to know the dosages to establish a suitable activity which achieves restenosis control and thereafter minimize radiation effects in the cardiac muscle. In order to accomplish the dosimetric analysis, a heart voxel model was assembled based on tomographic images. The computational model consists of a three-dimensional matrix taken from 60 tomographic images representing the major heart tissues. A radioactive ¹5³Sm liquid balloon is simulated as well as a ³²P radioactive stent, inserted in an arbitrary heart artery. After simulation processing, the absorbed dose rate was evaluated in the heart musculature. The models are presented in two- and three-dimensional previews and the dosage profiles are shown by isodose curves superimposed onto the heart model.

Gamma spectrometry and chemical characterization of ceramic seeds with samarium-153 and holmium-166 for brachytherapy proposal.

Ceramic seeds were synthesized by the sol-gel technique with Si:Sm:Ca and Si:Ho:Ca. One set of seeds was irradiated in the TRIGA type nuclear reactor IPR-R1 and submitted to instrumental neutron activation analysis (INAA), K(0) method, to determine mass percentage concentration of natural samarium and holmium in the seed as well as to determine all existing radionuclides and their activities. Attention was paid to discrimination of Si-31, Ca-40, Ca-45, Ca-47, Ca-49, Sm-145, Sm-155, Sm-153 and Ho-166. A second sample was submitted to atomic emission spectrometry (ICP-AES) also to determine samarium and holmium concentrations in weight. A third sample was submitted to X-ray fluorescence spectrometry to qualitatively determine chemical composition. The measured activity was due to Sm-153 and Ho-166 with a well-characterized gamma spectrum. The X-ray fluorescence spectrum demonstrated that there is no discrepancy in seed composition. The maximum ranges in the water of beta particles from Sm-153 and Ho-166 decay were evaluated, as well as the dose rate and total dose delivered within the volume delimited by the range of the beta particles. The results are relevant for investigation of the viability of producing Sm-153 and Ho-166 radioactive seeds for use in brachytherapy.

Structure and dosimetric analysis of biodegradable glasses for prostate cancer treatment.

This work analyzes SiO2 and SiO2-CaO glasses incorporated with samarium atoms produced by sol-gel synthesis. The goal is to provide biocompatible and biodegradable radioactive seeds as an alternative to be used in brachytherapy for the treatment of prostate cancer. The chemical and physical characteristics of the obtained glasses were analyzed by energy dispersive x-ray spectroscopy, x-ray diffraction, He picnometry, and nitrogen adsorption analysis. A theoretical analysis of the process of neutron activation of the samples was also conducted through the calculation of the activity of the seeds and the beta- and gamma-ray doses emitted by the seeds. The results demonstrate the incorporation of samarium atoms in the glass matrix. The experimental data coupled with the theoretical studies in neutron activation suggest that it is possible to obtain radioactive seeds with activities equivalent to 125I seeds used in prostatic brachytherapy.

Avaliaçäo da dose em braquiterapia acoplada à terapia por captura de nêutron por boro / Dosage evaluation in brachytherapy coupled to boron capturing therapy

Este trabalho descreve uma nova técnica radioterapêutica baseada no acoplamento de dois métodos distintos: a braquiterapia, proporcionada pela emissäo de nêutrons e raios gama de fontes mistas discretas colocadas em regiSes intracavitárias do paciente, e a captura neutrônica por boro (BNCT). Com o objetivo de estudar a "performance" do tratamento acoplado, avaliaçöes computacionais säo propostas para quantificar as doses absorvidas. Análises de possíveis fontes geradoras de nêutrons, a saber: fontes mistas discretas, reatores nucleares, aceleradores lineares tipo LINAC e dispositivos de nêutrons frios, säo apresentadas com o intuito de verificar a viabilidade técnica de instalaçäo e uso da terapia de nêutrons em hospitais.