Marcaje de arena sílice con 99mTc para la obtención de un radiotrazador sólido / Labeling of silica sand with 99mTc for obtaining a solid radiotracer

Resumen Para la obtención de radiotrazadores sólidos de 99mTc actualmente se necesitan nuevos soportes porosos. Estudios anteriores realizados por otros autores mostraron la posibilidad del marcaje con 99mTc de sedimentos de ríos con alto contenido de aluminosilicatos. En el presente trabajo se desarrolló una metodología para el marcaje de arena sílice con el 99mTcO4- para su uso como radiotrazador sólido. Se realizó el marcaje de la arena sílice previamente tratada y sin tratar empleando concentraciones variables de cloruro y fluoruro estañoso como agentes reductores y diferentes tiempos de marcaje. Se evaluó la influencia de la etapa de tratamiento previo de la arena en los rendimientos de retención del Tc obtenidos. Los cambios en la composición de la arena sílice luego de su tratamiento previo se pudieron constatar a partir de la Microscopía Electrónica de Barrido (SEM-EDS). Los resultados sugirieren el empleo de la arena sílice previamente tratada y de fluoruro estañoso como agente reductor, adicionalmente se propusieron modificaciones a la metodología inicial de tratamiento previo de la arena. Se pudo constatar a partir de la técnica SEM-EDS que el aumento del porciento de retención del Tc en la arena luego de su tratamiento, se debe fundamentalmente a los cambios observados en su composición química y en su estructura. Se logró la obtención de un radiotrazador sólido marcado con 99mTc en soporte de arena sílice con un tiempo de preparación estimado de 4 horas y un rendimiento de retención de 74%.

Abstract To obtain 99mTc solid radiotracers, new porous supports are currently needed. Previous studies carried out by other authors showed the possibility of 99mTc labeling of sediments from rivers with a high content of aluminosilicates. In the present work a methodology for labeling of silica sand with 99mTcO4- as a prospective solid radiotracer was developed. Labeling of the previously treated and untreated silica sand was carried out using variable concentrations of chloride and stannous fluoride as reducing agents and different labeling times. The influence of the pre-treatment stage of the sand on the obtained Tc retention yields was evaluated. The changes in the composition of the silica sand after its previous treatment could be verified from the Scanning Electron Microscopy (SEM-EDS). The results suggested the use of previously treated silica sand and stannous fluoride as a reducing agent, modifications were proposed to the initial methodology of previous treatment of the sand. It was possible to confirm from the SEM-EDS technique that the increase in the percentage of retention of Tc in the sand after its treatment is mainly due to the observed changes in its chemical composition and structure. It was possible to obtain a 99mTc solid radiotracer on support of silica sand with an estimated preparation time of 4 hours and a retention yield of 74%.

Molecular identification and mapping of a novel stripe rust resistance gene in wheat resistance line CH5389 / Identificação e mapeamento de um novo gene de resistência a ferrugem linear na linhagem de trigo CH5389

ABSTRACT: Stripe rust, caused by Puccinia striiformis is one of the most destructive diseases of wheat worldwide. CH5389 is a wheat-Thinopyrum intermedium derived line conferring stripe rust resistance. Genetic analyses of seedlings of F2 populations and F2:3 families developed by crossing CH5389 and susceptible common wheat revealed that stripe rust resistance in CH5389 was controlled by a single dominant gene that was designated YrCH5389. Eight SSR and EST-PCR polymorphic markers on chromosome 3AL were identified in F2 population of CH5389/Taichung29. The YrCH5389 was flanked by EST marker BE405348 and SSR marker Xwmc388 on chromosome 3AL with genetic distances of 2.2 and 4.6 cM, respectively. Comparative genomic analysis demonstrated that the orthologous genomic region of YrCH5389 covered 990 kb in rice, 640 kb in Brachypodium, and 890 kb in sorghum. Based on the locations of the markers, the resistance gene was located to chromosome deletion bin 3AL-0.85-1.00. Because there are no officially named stripe rust resistance genes on the 3AL chromosome, the YrCH5389 should be designated as a new resistance gene. These linkage markers could be useful for marker-assisted selection in wheat resistance breeding.

RESUMO: A ferrugem linear causada por Puccinia striiformis é uma das doenças mais destrutivas do trigo no mundo. A linhagem CH5389 é derivada do cruzamento de trigo com Thinopyrum intermedium e confere resistência a ferrugem linear. Análises genéticas de indivíduos da população F2 e família F2:3 obtida a partir do cruzamento entre CH5389 e trigo comum suscetível revelaram que a resistência à ferrugem linear na linhagem CH5389 foi controlada por um único gene dominante, designado YrCH5389. Oito marcadores polimórficos SSR e EST-PCR no cromossomo 3AL foram identificados na população F2 de CH5389/Taichung29. O gene YrCH5389 foi delimitado pelos marcadores EST BE405348 e SSR Xwmc388 no cromossomo 3AL com distâncias genéticas de 2,2 e 4,6 cM, respectivamente. Análises genômicas comparativas demonstraram que regiões genômicas ortólogas do gene YrCH5389 compreendem 990 kb em arroz, 640 kb em braquipódio e 890 kb em sorgo. Com base nas localizações dos marcadores, o gene de resistência foi localizado no cromossomo 3AL-0.85-1.00. Como não há genes oficialmente nomeados de resistência à ferrugem linear no cromossomo 3AL, o YrCH5389 deve ser designado como um gene novo de resistência. Esses marcadores de ligação podem ser úteis para a seleção assistida de genótipos de trigo resistentes a ferrugem linear.

Uso de solventes no acuosos en la síntesis del radioconjugado DOTA-1-Nal3-octreotida marcado con galio-68 / Use of non-aqueous solvents in the synthesis of radioconjugate DOTA-1-Nal3-octreotide labeled with gallium-68

Los tumores neuroendocrinos sobreexpresan receptores de somatostatina. Su diagnóstico se ha extendido debido al radiomarcaje de DOTA-péptidos como el análogo de somatostatina DOTA-1--octreotida (DOTA-NOC) conjugado con radionúclidos emisores ß+ como el , de propiedades físico-nucleares muy favorables. El presente trabajo describe los procedimientos para el radiomarcaje del DOTA-NOC con , en medio acuoso puro y en presencia de solventes no acuosos, así como los métodos usados para el control de calidad, donde se obtuvo una formulación con un rendimiento radioquímico superior al 95 %. La adición de etanol (30%- vol/vol) a la mezcla de reacción permitió incrementar la actividad específica del radioconjugado -DOTA-NOC, y se alcanzó un valor de 182 MBq/nmol, superior al reportado en la literatura (50 MBq/nmol) para el marcaje en medio acuoso puro. También se presentan los estudios de estabilidad (en presencia de solución salina y tampón fosfato salino), estudios de transmetalación en soluciones de , , y , competencia por retos contra los quelatos EDTA y DTPA y estabilidad in vitro en transferrina humana, realizados al radioconjugado -DOTA-NOC, del cual se mostró su elevada estabilidad (> 95 %). En comparación con el medio acuoso puro, el uso de solventes no acuosos en la síntesis del radioconjugado DOTA-1--octreotida marcado con galio-68, permite disminuir la masa de conjugado y los tiempos de reacción, incrementar significativamente los rendimientos y la actividad específica del compuesto marcado. Ello pudiera favorecer la obtención del producto con mejores características en sistemas modulares que se encuentran en fase de desarrollo.

Neuroendocrine tumors specifically over-express somatostatin receptors. Their diagnosis has expanded due to radiolabelling of DOTA-peptides such as somatostatin analogue DOTA-1--Octreotide (DOTA-NOC) conjugated to ß+ emitting radionuclides such as , with very favorable decay-properties. This paper describes the radiolabeling procedures of DOTA-NOC with , in a pure aqueous medium and in presence of non-aqueous solvents as well as the methods used for quality control where a formulation is obtained with a radiochemical yield exceeding 95%. Adding ethanol (30 % - v / v) to the reaction mixture allowed increasing the specific activity of -DOTA-NOC radioconjugated, reaching a value of 182 MBq / nmol, higher than reported in literature (50 MBq / nmol) for labeling in a pure aqueous medium. Stability studies are also presented (in presence of saline solution and saline phosphate buffer, transmetallation studies in , , and solutions, challenges competition against EDTA and DTPA chelators and in vitro stability in human transferrin) performed to -DOTA-NOC radioconjugated, showing its high stability (> 95 %). Compared with the aqueous medium, the use of non aqueous solvents in the synthesis of radioconjugate DOTA-1--octreotide labeled with gallium-68, helps reduce the mass of conjugate and the reaction time, significantly increase yields and specific activity of the labeled compound. This could facilitate obtaining the product with better characteristics in modular systems that are under development.

Radiofármacos en inmunocentelleografía y radioinmunoterapia / Radiopharmaceuticals in immunoscintigraphy and radioimmunotherapy

La alta morbilidad y letalidad del cáncer, hacen que esta enfermedad se considere, tanto en Cuba como en el mundo, un serio problema de salud. La radioimmunodiagnosis y la radioinmunoterapia, basadas en los crecientes avances en biotecnología y el conocimiento que hoy aportan la biología molecular y celular, devienen herramientas muy prometedoras en la lucha contra el cáncer. En este trabajo se hace una breve revisión de los radiofármacos desarrollados en Cuba, a partir de biomoléculas producidas y una panorámica de una serie de anticuerpos monoclonales y radionúclidos utilizados en aplicaciones clínicas. Las aplicaciones en radioimmunodiagnosis, se han basado en radiofármacos de 99mTc obtenidos a partir de kits liofilizados de anticuerpos monoclonales murinos. Se examinan también las perspectivas de la aplicación de radioinmunoterapia a partir de las experiencias internacionales, particularmente en el tratamiento del linfoma no Hodgkin, teniendo en cuenta la disponibilidad de diferentes anticuerpos monoclonales ya humanizados y de ? a partir de tecnologías existentes en centros cubanos de investigación-producción.

The high morbidity-mortality of cancer makes this condition in Cuba, and at international level, a serious health problem. Radioimmunodiagnosis and radioimmunotherapy based in the growing biotechnological advances, and the actual knowledge of molecular and cellular biology, become a highly promising tools in the fight against cancer. In this work we present a brief review of the radiopharmaceuticals developed in our country starting from biomolecules produced en Cuba, as well as a panoramic of several monoclonal antibodies and radionuclides used in clinical applications. Radioimmunodiagnosis applications are based on murine monoclonal antibodies, produced in form of lyophilized kits for ? labeling. We also examined the perspectives of the application of radioimmunotherapy in Cuba starting from the international experiences, particularly in non-Hodgkin’s lymphoma treatment, keeping in mind the availability of different monoclonal antibodies already humanized, as well as of ? from the existing technologies in Cuban research-production centers.

Análise crítica da aplicação da pesquisa do linfonodo sentinela no tratamento do câncer inicial de boca / Critical analysis of the sentinel lymph node biopsy in the treatment of early oral cancer

Introdução: A pesquisa do linfonodo sentinela (LNS) tende a diminuir as comorbidades do tratamento desnecessário referentes ao esvaziamento cervical. Objetivo: Avaliar a efetividade do LNS na detecção de metástases ocultas em pacientes com carcinoma espinocelular (CEC) de boca. Métodos: Estudo prospectivo com 25 pacientes com CEC de boca T1/T2 com pescoço N0. A linfocintigrafia pré-operatoria foi feita com 99mTc-fitato injetado peri-lesional. O local do LNS era marcado pela medicina nuclear. No peroperatório, era injetado azul patente peri-lesional e os LNS avaliados com um gama probe. Após a pesquisa do LNS, todos foram submetidos a esvaziamento cervical seletivo, conforme o padrão do serviço. Todos os LNS foram enviados para estudo anatomo-patológico para comparação. Resultados: O local mais frequente foi a língua, com 62% e o soalho, 38%. Em relação ao estadiamento, 56% eram T2 e 44% T1. Do total de pacientes, 25% tiveram LNS positivo, sendo todos detectados na pesquisa do LNS, com sensibilidade de 100%, especificidade de 8% e verdadeiros-negativo de 100%, porém, encontramos problemas como: interferência na detecção da radiação pela proximidade do tumor-LNS, múltiplos LNS, LNS pequenos, profundos, múltiplos níveis e não corados pelo azul. Conclusão: A pesquisa do LNS pode diminuir a morbidade do esvaziamento cervical. Em virtude de vários fatores, principalmente a alta taxa de interferência (tumor-linfonodo) essa técnica ainda não deve ser o padrão para o tratamento do pescoço nesses pacientes, devendo existir um estudo multicêntrico prospectivo avaliando sua eficácia oncológica em cinco anos.

Introduction: The management of the neck in oral cavity cancer is still a challenge for the head and neck surgeon. Objective: To assess the feasibility of the sentinel lymph node (SLN) in squamous cell carcinoma (SCC) of the oral cavity staging T1/T2. Methods: It was a prospective study with 25 patients with N0 SCC of the oral cavity. Lymphoscintigraphy with 99mT was done before the surgery and the lymph node spot was marked. In the operation room, blue dye was injected around the tumor and the sentinel lymph node evaluated with a gamma probe. After the research of the sentinel lymph node, all patients underwent the selective neck dissection. All lymph nodes were submitted for histopathological study. Results: The most frequent location was the tong (62%) followed by the floor of the mouth (38%). The stage was 56% for T2 and 44% for T1. A rate of 25% of the patients had positive SLN, but one of them had 4 other lymph nodes compromised. The sensibility was 100%, specificity 8% and true negative 100%, but there were problems, such as the interference in the detection of radiation next the tumor, multiples SLN, small, deep and multiples levels of SLN, does not colored for blue dye. Twelve patients (75%) had all the lymph nodes negative. Conclusion: Sentinel lymph node biopsy will get a great importance in reducing the comorbidity of neck dissection. However, because of many factors, mainly the great interference (tumor-lymph node) this technique must not be the gold standard for the treatment of the neck in early oral cancer up to now.

Fine scale gene flow and individual movements among subpopulations of Centrolene prosoblepon (Anura: Centrolenidae)

Dispersal capabilities determine and maintain local gene flow, and this has implications for population persistence and/or recolonization following environmental perturbations (natural or anthropogenic), disease outbreaks, or other demographic collapses. To predict recolonization and understand dispersal capacity in a stream-breeding frog, we examined individual movement patterns and gene flow among four subpopulations of the Neotropical glassfrog, Centrolene prosoblepon, at a mid-elevation cloud forest site at El Copé, Panama. We measured male movement directly during a two year mark-recapture study, and indirectly with gene flow estimates from mitochondrial DNA sequences (mtDNA). Individuals of this species showed strong site fidelity: over two years, male frogs in all four headwater streams moved very little (mean = 2.33 m; mode = 0 m). Nine individuals changed streams within one or two years, moving 675-1,108 m. For those males moving more than 10 m, movement was biased upstream (p < 0.001). Using mtDNA ND1 gene sequences, we quantified gene flow within and among headwater streams at two spatial scales: among headwater streams within two adjacent watersheds (2.5 km2) and among streams within a longitudinal gradient covering 5.0 km2. We found high gene flow among headwater streams (phi(ST) = 0.007, p = 0.325) but gene flow was more limited across greater distances (phi(CT) = 0.322, p = 0.065), even within the same drainage network. Lowland populations of C. prosoblepon potentially act as an important source of colonists for upland populations in this watershed.

La capacidad de dispersión determina y mantiene el flujo genético local, y esto tiene implicaciones para la persistencia poblacional y/o la recolonización que sigue a perturbaciones ambientales. Examinamos patrones individuales de movimiento y flujo genético entre subpoblaciones de Centrolene prosoblepon (Anura: Centrolenidae) en un sitio de elevación media en El Copé, Panamá. Medimos directamente el movimiento de los machos durante un estudio de marcado-recaptura, e indirectamente con estimaciones de flujo genético a partir de secuencias de ADN mitocondrial (mtDNA). Los individuos mostraron fuerte fidelidad a su lugar: por más de dos años, las ranas macho de los cuatro arroyos al inicio del río se movieron muy poco (promedio = 2.33 m; moda = 0 m). Nueve individuos cambiaron de corriente de agua en uno o dos años, moviéndose 675-1 108 m. Usando la secuencia genética ND1 del ADN mitocondrial, medimos el flujo genético en dos escalas espaciales: entre arroyos que originan el río (2.5 km2) y entre arroyos con un gradiente longitudinal en 5.0 km2. Encontramos un flujo genético alto entre los arroyos al inicio del río (f = 0.007, p = 0.325 y otro más limitado en distancias mayores (f = 0.322, p = 0.065).