Estudio de biomonitorización de una población de trabajadores expuestos al arsénico y caracterización de los posibles factores moduladores del daño genotóxico

Consultable des del TDXTítol obtingut de la portada digitalitzadaAl arsénico se le considera un problema de salud mundial debido a la cantidad de poblaciones expuestas crónicamente al mismo y a la gravedad de los efectos inducidos, incluyendo el incremento de algunos tipos de cáncer. Aunque los mecanismos de acción del arsénico no están del todo dilucidados, está ampliamente aceptado su potencial citotóxico, genotóxico y carcinógeno. En este trabajo se pretende estudiar sus efectos genotóxicos, entender los mecanismos implicados en el proceso de su metabolización e investigar posibles biomarcadores de susceptibilidad asociados a la exposición. Inicialmente, se llevó a cabo un estudio de biomonitorización para averiguar las posibles correlaciones entre efectos genotóxicos y exposición ocupacional al arsénico. Se utilizaron los niveles de arsénico y de sus metabolitos en orina como biomarcador de exposición y los ensayos de MN y de SCE como medida de daño citogenético. Dado que recientemente se ha propuesto que los dos miembros funcionales de la nueva clase Omega, GSTO1 y GSTO2, juegan un papel importante en la homeostasis celular, estando también involucradas en la biotransformación del arsénico, hemos postulado que, polimorfismos en estos genes podrían estar correlacionados con cambios en la actividad de estas proteínas que lleven a diferencias en el perfil de excreción del arsénico y, consecuentemente, a diferencias de respuesta frente a una exposición. La segunda parte del trabajo ha consistido en el análisis de los polimorfismos de GSTO1 y de GSTO2 entre tres grupos étnicos y en la caracterización enzimática de dos de las variantes de GSTO1. Además, los polimorfismos de GSTO1 y de GSTO2 también se han analizado en la población de trabajadores chilenos, estableciéndose correlaciones entre genotipos, perfil de excreción y daño citogenético, integrando así las dos partes del estudio. A pesar de los avances en los estudios de expresión de GTSO1, el papel que ejerce esta enzima en el metabolismo y en la toxicidad del arsénico sigue en discusión. Así, se han utilizado dos líneas celulares con diferentes niveles de expresión de GSTO1, junto con la reducción de sus niveles de expresión mediante la técnica de RNAi, para evaluar las diferencias de respuesta frente a distintos compuestos de arsénico. No se han detectado diferencias en la toxicidad del arsénico relacionadas con los diferentes niveles de expresión. En contraste, la reducción del estrés oxidativo por la NAC indica que diferencias en los niveles de GSTO1 pueden estar modulando las diferencias de respuesta al estrés oxidativo inducido por los compuestos de arsénico. Nuestros resultados no excluyen la participación de otras enzimas en el proceso de biotransformación y toxicidad del arsénico.Arsenic has become a major world health problem, due to the size of the exposed population and the seriousness of its effects, which are mainly related with the increase of cancer cases among the chronically exposed populations. Even though the mechanisms of action of this element are not fully understood, it has been clearly reported that it is cytotoxic, genotoxic and carcinogenic in humans. In this context, we planned to study the genotoxic effect of this metal, to understand the metabolic mechanisms involved in this process, and to find biomarkers of susceptibility to arsenic exposure. Initially, a biomonitoring study was carried out to investigate the correlation between arsenic occupational exposure and genotoxic effects in smelting plant workers, using the levels of arsenic and its metabolites excreted in urine as an exposure biomarker and the SCE and the MN assays as measures of cytogenetic damage. Two members of the recently identified Omega class glutathione S-transferase enzymes (GSTO1 and GSTO2) have been proposed to play an important role in cellular homeostasis and in the arsenic reduction pathway. Therefore, polymorphisms in these genes could be related with variations in the protein activity leading to changes in the arsenic excretion profile, and consequently with the response to chronic exposures. The second part of this study was based on the analysis of hGSTO1/2 polymorphisms among three ethnical groups and the enzymatic characterization of two GSTO1 variants. Moreover, GSTO1 and GSTO2 polymorphisms were also analyzed in the Chilean workers. Then, the first and the second part of this work have been linked, establishing correlations among genotypes, variations of urine arsenic profile and cytogenetic damage. Despite the recent progress in the study of GSTOs expression and pharmacokinetics, the role of these enzymes in the arsenic metabolism and toxicity is under discussion. To clarify this, two cell lines with different expression levels of GSTO1 have been used to evaluate the cytotoxic response of various arsenic compounds. In addition, depletion of the GSTO1 levels with siRNA has also been used. Results do not shown significant variations in arsenic toxicity, according to the different expression levels. In contrast, reduction of oxidative stress by NAC indicates that differences at GSTO1 expression levels could modulate the response to the oxidative stress induced by arsenic compounds. These results do not rule out others enzymes participating in the arsenic metabolism and toxicity

The challenges in the application of educational strategies for doctors in the Programa Mais Médicos do Brasil (PMMB): An analytical-descriptive study

This article analyzes the challenges faced for the application of educational strategies for physicians in the Programa Mais Médicos of Brasil (“More Physicians”) and the contributions of these professionals to the work processes of Family Health teams with a focus on achieving comprehensiveness of health care and the expansion of health care. access to hard-to-reach regions. It is a documentary analysis of a descriptive nature, which includes from laws and regulations, norms, opinions, letters, memo, personal diaries, autobiographies, newspapers, magazines, speeches, radio and television program scripts to books, statistics and files schoolchildren. The results indicate that there is a need for dynamic flexibility in educational actions, focusing on the needs of the population and regions that host the program to reduce care inequities and favor the strengthening of bonds between staff and users in order to provide comprehensive care . Among the challenges, we can highlight the program\u27s contribution to the reduction of practices segmented by professional categories, subordinated to the (bio)medical figure and knowledge, with limited interprofessional and team-community interaction in the construction of common care and interconstitutive knowledge. However, it could be concluded that the contribution of the doctors of the “Mais Médicos” Program in Brazil, in addition to reducing inequities and expanding access to healthcare for the population, also contributes to the deconstruction of the hegemonic medical model, taking into account the importance of interdisciplinary knowledge for the success of comprehensive health care. In addition, it reiterates the importance of dynamic actions focusing on local and territorial reality for educational strategies, as territories have peculiar characteristics, developing the critical-reflective process of professionals and capable of solving demands in different regions

Estudio de biomonitorización de una población de trabajadores expuestos al arsénico y caracterización de los posibles factores moduladores del daño genotóxico

Al arsénico se le considera un problema de salud mundial debido a la cantidad de poblaciones expuestas crónicamente al mismo y a la gravedad de los efectos inducidos, incluyendo el incremento de algunos tipos de cáncer. Aunque los mecanismos de acción del arsénico no están del todo dilucidados, está ampliamente aceptado su potencial citotóxico, genotóxico y carcinógeno. En este trabajo se pretende estudiar sus efectos genotóxicos, entender los mecanismos implicados en el proceso de su metabolización e investigar posibles biomarcadores de susceptibilidad asociados a la exposición.Inicialmente, se llevó a cabo un estudio de biomonitorización para averiguar las posibles correlaciones entre efectos genotóxicos y exposición ocupacional al arsénico. Se utilizaron los niveles de arsénico y de sus metabolitos en orina como biomarcador de exposición y los ensayos de MN y de SCE como medida de daño citogenético.Dado que recientemente se ha propuesto que los dos miembros funcionales de la nueva clase Omega, GSTO1 y GSTO2, juegan un papel importante en la homeostasis celular, estando también involucradas en la biotransformación del arsénico, hemos postulado que, polimorfismos en estos genes podrían estar correlacionados con cambios en la actividad de estas proteínas que lleven a diferencias en el perfil de excreción del arsénico y, consecuentemente, a diferencias de respuesta frente a una exposición. La segunda parte del trabajo ha consistido en el análisis de los polimorfismos de GSTO1 y de GSTO2 entre tres grupos étnicos y en la caracterización enzimática de dos de las variantes de GSTO1. Además, los polimorfismos de GSTO1 y de GSTO2 también se han analizado en la población de trabajadores chilenos, estableciéndose correlaciones entre genotipos, perfil de excreción y daño citogenético, integrando así las dos partes del estudio.A pesar de los avances en los estudios de expresión de GTSO1, el papel que ejerce esta enzima en el metabolismo y en la toxicidad del arsénico sigue en discusión. Así, se han utilizado dos líneas celulares con diferentes niveles de expresión de GSTO1, junto con la reducción de sus niveles de expresión mediante la técnica de RNAi, para evaluar las diferencias de respuesta frente a distintos compuestos de arsénico. No se han detectado diferencias en la toxicidad del arsénico relacionadas con los diferentes niveles de expresión. En contraste, la reducción del estrés oxidativo por la NAC indica que diferencias en los niveles de GSTO1 pueden estar modulando las diferencias de respuesta al estrés oxidativo inducido por los compuestos de arsénico. Nuestros resultados no excluyen la participación de otras enzimas en el proceso de biotransformación y toxicidad del arsénico.Arsenic has become a major world health problem, due to the size of the exposed population and the seriousness of its effects, which are mainly related with the increase of cancer cases among the chronically exposed populations. Even though the mechanisms of action of this element are not fully understood, it has been clearly reported that it is cytotoxic, genotoxic and carcinogenic in humans. In this context, we planned to study the genotoxic effect of this metal, to understand the metabolic mechanisms involved in this process, and to find biomarkers of susceptibility to arsenic exposure.Initially, a biomonitoring study was carried out to investigate the correlation between arsenic occupational exposure and genotoxic effects in smelting plant workers, using the levels of arsenic and its metabolites excreted in urine as an exposure biomarker and the SCE and the MN assays as measures of cytogenetic damage.Two members of the recently identified Omega class glutathione S-transferase enzymes (GSTO1 and GSTO2) have been proposed to play an important role in cellular homeostasis and in the arsenic reduction pathway. Therefore, polymorphisms in these genes could be related with variations in the protein activity leading to changes in the arsenic excretion profile, and consequently with the response to chronic exposures. The second part of this study was based on the analysis of hGSTO1/2 polymorphisms among three ethnical groups and the enzymatic characterization of two GSTO1 variants. Moreover, GSTO1 and GSTO2 polymorphisms were also analyzed in the Chilean workers. Then, the first and the second part of this work have been linked, establishing correlations among genotypes, variations of urine arsenic profile and cytogenetic damage. Despite the recent progress in the study of GSTOs expression and pharmacokinetics, the role of these enzymes in the arsenic metabolism and toxicity is under discussion. To clarify this, two cell lines with different expression levels of GSTO1 have been used to evaluate the cytotoxic response of various arsenic compounds. In addition, depletion of the GSTO1 levels with siRNA has also been used. Results do not shown significant variations in arsenic toxicity, according to the different expression levels. In contrast, reduction of oxidative stress by NAC indicates that differences at GSTO1 expression levels could modulate the response to the oxidative stress induced by arsenic compounds. These results do not rule out others enzymes participating in the arsenic metabolism and toxicity

Polymorphism of glutathione transferase Omega 1 in a population exposed to a high environmental arsenic burden

OBJECTIVES AND METHODS: The aim of this study was to investigate genetic variation in glutathione transferase omega 1 (GSTO1-1) in Atacameños, an indigenous population from Chile that has been exposed to environmental arsenic for many generations. GSTO1

Polymorphism of glutathione transferase Omega 1 in a population exposed to a high environmental arsenic burden

OBJECTIVES AND METHODS: The aim of this study was to investigate genetic variation in glutathione transferase omega 1 (GSTO1-1) in Atacameños, an indigenous population from Chile that has been exposed to environmental arsenic for many generations. GSTO1-1 is thought to catalyse the rate-limiting step in the biotransformation of arsenic in humans and may modulate the response of cancer patients to arsenic trioxide therapy. Allele frequencies were determined by PCR-based methods and a polymorphic variant (GSTO1-1 Val236) was expressed in Escherichia coli and functionally characterized. Urinary arsenic profiles were determined by inductive coupled plasma/mass spectrometry. RESULTS: A novel allele resulting in an Ala236Val substitution that has not been functionally characterized was detected in Atacameños and Chilean participants at a frequency of 0.033 and 0.009, respectively. The Val236 isoenzyme has diminished specific activity (10-20%) with a range of substrates. This loss of activity appears to result from a decrease in the kcat. The Val236 variant is also unstable and rapidly loses activity during purification or when heated at 45 degrees C. The percent of inorganic arsenic in the urine of 205 Chilean participants showed a bimodal distribution that was not associated with the Ala140Asp, Glu155del or Ala236Val polymorphisms in GSTO1-1. CONCLUSION: It is likely that heterozygotes inheriting the Val236 variant subunit would have a partial deficiency of GSTO1-1 activity. Despite their effects on enzyme function the known variants of GSTO1-1 do not appear to explain the observed variability in the excretion of inorganic arsenic

Metabolomic Study of Urine from Workers Exposed to Low Concentrations of Benzene by UHPLC-ESI-QToF-MS Reveals Potential Biomarkers Associated with Oxidative Stress and Genotoxicity

Benzene is a human carcinogen whose exposure to concentrations below 1 ppm (3.19 mg·m−3) is associated with myelotoxic effects. The determination of biomarkers such as trans-trans muconic acid (AttM) and S-phenylmercapturic acid (SPMA) show exposure without reflecting the toxic effects of benzene. For this reason, in this study, the urinary metabolome of individuals exposed to low concentrations of benzene was investigated, with the aim of understanding the biological response to exposure to this xenobiotic and identifying metabolites correlated with the toxic effects induced by it. Ultra-efficient liquid chromatography coupled to a quadrupole-time-of-flight mass spectrometer (UHPLC-ESI-Q-ToF-MS) was used to identify metabolites in the urine of environmentally (n = 28) and occupationally exposed (n = 32) to benzene (mean of 22.1 μg·m−3 and 31.8 μg·m−3, respectively). Non-targeted metabolomics analysis by PLS-DA revealed nine urinary metabolites discriminating between groups and statistically correlated with oxidative damage (MDA, thiol) and genetic material (chromosomal aberrations) induced by the hydrocarbon. The analysis of metabolic pathways revealed important alterations in lipid metabolism. These results point to the involvement of alterations in lipid metabolism in the mechanisms of cytotoxic and genotoxic action of benzene. Furthermore, this study proves the potential of metabolomics to provide relevant information to understand the biological response to exposure to xenobiotics and identify early effect biomarkers