Cromosomopatías en pacientes con cáncer sometidos a radioterapia con cobalto 60 / Chromosomopathies in cancer patients undergoing cobalt 60 radiotherapy

Objetivo: Describir las aberraciones citogenéticas que pueden ser observadas por medio de la técnica Giemsa en fluorescencia y encontradas en pacientes con cáncer antes y después de ser sometidos a tratamiento con radioterapia. Métodos: Se analizó un mínimo de 200 metafases en primera división mitótica antes y después del tratamiento de radioterapia en nueve pacientes que asistieron a la sección de radioterapia del Hospital San Juan de Dios Costa Rica. En cada caso se contabilizó cada tipo de cromosomopatía por medio de la prueba de Giemsa en fluorescencia y utilizando bromodeoxiuridina y naranja de acridina. Resultados: Las cromosomopatías producidas por radioterapia se observaron tanto antes como después del tratamiento sin embargo destacó el incremento en la frecuencia de los cromosomas dicéntricos y anillos céntricos una vez finalizada la terapia. La frecuencia de fracturas cromatídicas de asociaciones satelíticas y de alteraciones morfológicas no se ve afectada por la radioterapia. Uno de los participantes presentó un recuento mitótico bajo. Conclusión: La radioterapia aumenta significativamente la frecuencia de los cromosomas dicéntricos y dicéntricos más anillos en la muestra en estudio. Este trabajo es relevante por ser el primer estudio en Costa Rica en el que se analizan los cromosomas dicéntricos como biomarcadores de exposición a radiaciones ionizantes mediante la prueba de Giemsa en fluorescencia y utilizando bromodeoxiuridina y naranja de acridina.

Aim: The objective of this study was to describe the before and after cytogenetic aberrations found in current patients of radiotherapy. This can be observed through the technique called "Giemsa in fluorescence" Methods: A minimum of 200 metaphases were analyzed in the first mitotic division in 9 patients. The patients where observed before and after radiotherapy treatment at the San Juan de Dios Hospital in Costa Rica. In each case any type of chromosomopathy was counted using the "Giemsa in fluorescence" test as well as Bromodeoxyuridine and acridine orange. Results: The chromosomopathies are observed before and after treatment with radiotherapy. The treatment seems to change the frecuency increasing the dicentric chromosomes and centric rings after the treatment. The frequency of chromatid fractures satellite associations and morphological alterations were not affected by radiotherapy. Conclusion: The chromosomopathies produced by radiotherapy were observed both before and after treatment with variations in their frequency. After radiotherapy dicentric chromosomes and dicentric chromosomes plus rings frequencies increased significantly. A low mitotic count was present this could have been the result of radiation on the bone marrow or by the cell repair and apoptosis system. The standardized " Fluorescence Plus Giemsa" test using Bromodesoxyuridine and acridine orange was used for the fiesta time in Costa Reica. This allowed for the measurement of radiation exposure used in the treatment or detection of diseases and cancer in pacients.

Inicio de la Dosimetría Biológica en Costa Rica y su importancia en la atención de poblaciones sobreexpuestas a radiaciones / Beginning of Biological Dosimetry in Costa Rica and its importance in the care of populations overexposed to ionizing radiation

Resumen Introducción: el laboratorio de citogenética del Instituto de Investigaciones en Salud (INISA) de la Universidad de Costa Rica estableció un Servicio de Dosimetría Biológica en enero del 2020 utilizando biomarcadores citogenéticos de exposición a radiaciones ionizantes. Es el primero de su tipo en la región centroamericana. Objetivo: establecer un servicio de dosimetría biológica para Costa Rica, elaborando una curva de calibración dosis-efecto para rayos gamma. Metodología: para la realización de la curva de calibración se irradiaron muestras de sangre periférica in vitro con rayos gamma de dos voluntarios, uno femenino y otro masculino, en 11 puntos de dosis en el rango de 0 a 5 Gy. Se cultivó la sangre acorde a los protocolos internacionales durante 48 horas y se registraron las aberraciones inducidas. Los programas Dose Estimate V5.2 y R versión 4.03 se utilizaron para el cálculo de los coeficientes de la curva de calibración que correlaciona la frecuencia de cromosomas dicéntricos con la dosis. Resultados: los coeficientes de la curva son α: 0.02737±0.00658, ß: 0,05938±0,00450 y C: 0.00129±0.00084. Estos coeficientes tienen valores similares a los reportados internacionalmente. La curva se validó calculando dos dosis incógnitas, en la primera incógnita la dosis suministrada fue de 1,5 Gy y la dosis estimada fue 1,47 Gy y en la segunda la dosis suministrada fue de 4 Gy y la dosis estimada fue 3,616 Gy, para ambos casos no existen diferencias estadísticamente significativas entre las dosis suministradas y las estimadas. Conclusiones: actualmente El Servicio de Dosimetría Biológica del INISA puede estimar dosis absorbida en personas que se sospecha de una sobre exposición a rayos gamma en personal ocupacionalmente expuesto o personas involucradas en un accidente radiológico.

Abstract Introduction. The cytogenetics laboratory of the Health Research Institute (INISA) of the University of Costa Rica established a Biological Dosimetry Service in January 2020 using cytogenetic biomarkers of exposure to ionizing radiation. It is the first of its kind in the Central American region. Objective: establish a biological dosimetry service for Costa Rica, developing a dose-effect calibration curve for gamma rays. Methodology: to carry out the calibration curve, peripheral blood samples from two volunteers, one female and the other male, were irradiated in vitro with gamma rays, at 11 dose points in the range of 0 to 5 Gy. Blood was cultured according to international protocols for 48 hours and induced aberrations were recorded. The Dose Estimate V5.2 and R version 4.03 programs were used to calculate the coefficients of the calibration curve that correlates the frequency of dicentric chromosomes with the dose. Results: the coefficients of the curve are α: 0.02737 ± 0.00658, ß: 0.05938 ± 0.00450 and C: 0.00129 ± 0.00084. These coefficients have values similar to those reported internationally. The curve was validated by calculating two unknown doses, in the first unknown case the delivered dose was 1.5 Gy and the estimated dose was 1.47 Gy and in the second case the delivered dose was 4 Gy and the estimated dose was 3.616 Gy. for both cases there are no statistically significant differences between the delivered and estimated doses. Conclusions: the Biological Dosimetry Service of the INISA can estimate absorbed dose in persons suspected of overexposure to gamma rays in occupationally exposed personnel or persons involved in a radiological accident.Health is loaded with symbolisms and practical manifestations that differ according to social groups and sociocultural contexts. In order to make everyday life and needs visible, the Theoretical Paradigm of Social Representations provides the theoretical-methodological bases necessary to understand the common sense knowledge associated with health among the Nicaraguan migrant population in Costa Rica. Methodology: Qualitative study with ethnographic approach that aimed to identify the social representation of health, through the process of objectification, present among Nicaraguan migrants living in Costa Rica. Data collected through semi-structured interviews, participant observation, and field diaries. Processing according to Content Analysis. Results: The social representation of health found behaves analogously to a formula; where, the search for peaceful environments is added to the achievement of financial stability to result in two interdependent representations: 1) Health as physical-mental strength; and 2) Health as a future and abstract sensation of well-being, happiness and transcendence. The socio-political antecedents in Nicaragua, the migratory process, and the adaptation to Costa Rica play a preponderant role in shaping the representation on health. Conclusion: Social representations about health have direct practical implications on the ways of life and needs of migrant groups. Understanding their common sense knowledge allows to move towards more contextualized public policies. More integration of the thoughts, opinions and feelings of migrants in decision-making platforms is recommended.

The hCOMET project: International database comparison of results with the comet assay in human biomonitoring. Baseline frequency of DNA damage and effect of main confounders.

The alkaline comet assay, or single cell gel electrophoresis, is one of the most popular methods for assessing DNA damage in human population. One of the open issues concerning this assay is the identification of those factors that can explain the large inter-individual and inter-laboratory variation. International collaborative initiatives such as the hCOMET project - a COST Action launched in 2016 - represent a valuable tool to meet this challenge. The aims of hCOMET were to establish reference values for the level of DNA damage in humans, to investigate the effect of host factors, lifestyle and exposure to genotoxic agents, and to compare different sources of assay variability. A database of 19,320 subjects was generated, pooling data from 105 studies run by 44 laboratories in 26 countries between 1999 and 2019. A mixed random effect log-linear model, in parallel with a classic meta-analysis, was applied to take into account the extensive heterogeneity of data, due to descriptor, specimen and protocol variability. As a result of this analysis interquartile intervals of DNA strand breaks (which includes alkali-labile sites) were reported for tail intensity, tail length, and tail moment (comet assay descriptors). A small variation by age was reported in some datasets, suggesting higher DNA damage in oldest age-classes, while no effect could be shown for sex or smoking habit, although the lack of data on heavy smokers has still to be considered. Finally, highly significant differences in DNA damage were found for most exposures investigated in specific studies. In conclusion, these data, which confirm that DNA damage measured by the comet assay is an excellent biomarker of exposure in several conditions, may contribute to improving the quality of study design and to the standardization of results of the comet assay in human populations.

CPHR: 35 años al Servicio de la Protección Radiológica, la Salud y el Medio Ambiente / CPHR: 35 years at the Service of Radiological Protection, Health and the Environment

Resumen El Centro de Protección e Higiene de las Radiaciones fue fundado en 1985 para sustentar la aplicación segura de las tecnologías nucleares en Cuba. En la actualidad la institución es considerada como una referencia nacional y regional en materia de seguridad radiológica, gracias a una sólida estrategia institucional que aporta de manera sostenida soluciones a problemas prioritarios del país. Este trabajo presenta una reseña de los principales resultados del centro hasta la fecha.

Abstract The Center for Radiation Protection and Hygiene was founded in 1985 to support the safe application of nuclear technologies in Cuba. Nowdays, the institution is considered as a national and regional reference for radiation protection , thanks to the comprehensive institutional strategy that support the solutions of the problems with priority in the country. The paper presents the overview about the main results of the center up today.

Dose response of prematurely condensed chromosome rings after gamma irradiation.

PURPOSE: This paper presents a calibration curve for prematurely condensed chromosome rings (PCC-ring) which are scarce in cytogenetic dosimetry; here we analyzed the behavior of the PCC-ring frequency and PCC index after gamma irradiation in the dose interval from 0 to 20 Gy. MATERIALS AND METHODS: PCC-rings were induced in lymphocytes with Calyculin A. A total of 5788 PCC cells in G1, G2/M, and M/A stages were analyzed. RESULTS: The best fitting curve between the frequency of PCC ring (Y) and the Dose (D) was obtained with the equation Y = (0.0308 ± 0.0012) D. The distribution of rings by cell followed a Poisson distribution. The PCC index was correlated with radiation dose and decreased in a dose-dependent manner. CONCLUSION: This PCC-ring dose-effect curve can be used in case of high dose accidental overexposure to gamma radiation, allowing a dose assessment in a reliable way in most of the simulated irradiation analyzed.

Nuevas curvas de calibración para la dosimetría biológica en Cuba / New calibration curves for biological dosimetry in Cuba

RESUMEN Se muestran 11 curvas dosis respuesta in vitro obtenidas por primera vez en el país para tres indicadores biológicos: anillos en cromosomas prematuramente condensados (PCC-R) índice PCC; focos gamma H2AX (-H2AX), todos ellos en linfocitos de sangre periférica humana. Estas curvas en su conjunto cubren un intervalo de dosis desde 0,1 Gy hasta 25 Gy, y varias calidades de radiación, así como varios tiempos post exposición, lo cual fortalece las capacidades para dar respuesta a las emergencias radiológicas y amplía las posibilidades de contribuir al esclarecimiento de cualquier suceso radiológico anormal que pueda ocurrir en la región, donde el indicador predominante en la actualidad continúa siendo la cuantificación de dicéntricos en linfocitos de la sangre periférica.

ABSTRACT In this paper we show the dose response curves in vitro obtained at first time in Cuba, with several biological indicators for radiation damage: rings in premature chromosome condensation (PCC-R); PCC index and -H2AX foci, all of these in peripheral human lymphocytes. These curves cover an interval of doses between 0.1 Gy to 25 Gy, several radiation qualities and times post-exposition, strengthening the capabilities of the Cuban laboratory to give answer to the radiological emergencies and in the same way increase its contribution to elucidate any radiological abnormal event take place at the region where the main indicator at the present time is the dicentric assay in lymphocytes of peripheral blood.