Comparación entre riesgos competitivos vía el estimador cópula-gráfico

En riesgos competitivos, el problema de identificabilidad asociado a la dependencia entre los modos de falla, se puede resolver utilizando el estimador cópula-gráfico que asume la forma de la cópula conocida. En este trabajo se compara, mediante simulación, este estimador para un modelo de riesgos competitivos dependientes con el estimador tradicional que asume independencia. Se muestra que ignorar la dependencia puede causar subestimación significativa de la función de confiabilidad. Se ilustra la temática con un ejemplo y se visualiza a futuro la posible utilidad del estimador cópulagráfico en confiabilidad industrial para predecir en experimentos acelerados.The identifiability problem in competing risks associated to the dependence measure between the failure modes, can be solved by means of the copula-graphic estimator which assumes the copula function known. This paper compares, through a simulation study, the copula-graphic estimator for a dependent competing risks model with the traditional one under the assumption of independence. It is shown that a significant subestimation of the reliability function can be made when the dependence is not taken into account. An example ilustrates this point and as a future work it is seen the possibility of using copula-graphic in industrial reliability to predict in accelerated life tests

Neurobehavioral And Oxidative Stress Alterations Following Methylmercury And Retinyl Palmitate Co-Administration In Pregnant And Lactating Rats And Their Offspring

Fish consumption and ubiquitous methylmercury (MeHg) exposure represent a public health problem globally. Micronutrients presented in fish affects MeHg uptake/distribution. Vitamin A (VitA), another fish micronutrient is used in nutritional supplementation, especially during pregnancy. However, there is no information about the health effects arising from their combined exposure. The present study aimed to examine the effects of both MeHg and retinyl palmitate administered to pregnant and lactating rats. Thirty Wistar female rats were orally supplemented with MeHg (0,5 mg/Kg/day) and retinyl palmitate (7500 μg RAE1/Kg/day), either individually or in combination from the gestational day 0 to weaning. In dams, maternal behavior was scored. In neonatal and infant offspring, associative learning and neurodevelopment were evaluated. Further periadolescent male and female pups were assessed for open field, habituation and object recognition using episodic-like memory paradigm. Maternal and offspring redox parameters were evaluated. Our results showed no effects of MeHg-VitA co-administration in the quality of maternal care but showed subtle alterations in the pro-oxidant response of the hippocampus. In offspring, MeHg-VitA co-exposure affected early associative learning in neonatal pups, with no further modifications in neurodevelopment, and no locomotor or exploratory alterations in later developmental stages. Habituation was altered in a sex-dependent manner, but no overall memory disturbances were encountered

Effects Of Methylmercury And Retinol Palmitate Co-Administration In Rats During Pregnancy And Breastfeeding: Metabolic And Redox Parameters In Dams And Their Offspring

Ubiquitous low-dose methylmercury (MeHg) exposure through an increased fish consumption represents a global public health problem, especially among pregnant women. A plethora of micronutrients presented in fish affects MeHg uptake/distribution, but limited data is available. Vitamin A (VitA), another fish micronutrient is used in nutritional supplementation, especially during pregnancy. However, there is no information about the health effects arising from their combined exposure. Therefore, the present study aimed to examine the effects of both MeHg and retinyl palmitate administered on pregnant and lactating rats in metabolic and redox parameters from dams and their offspring. Thirty Wistar female rats were orally supplemented with MeHg (0,5 mg/kg/day) and retinyl palmitate (7500 µg RAE/kg/day) via gavage, either individually or in combination from the gestational day 0 to weaning. For dams (150 days old) and their offspring (31 days old), glycogen accumulation (hepatic and cardiac) and retinoid contents (plasma and liver) were analyzed. Hg deposition in liver tissue was quantified. Redox parameters (liver, kidney, and heart) were evaluated for both animals. Cytogenetic damage was analyzed with micronucleus test. Our results showed no general toxic or metabolic alterations in dams and their offspring by MeHg-VitA co-administration during pregnancy and lactation. However, increased lipoperoxidation in maternal liver and a disrupted pro-oxidant response in the heart of male pups was encountered, with apparently no particular effects in the antioxidant response in female offspring. GST activity in dam kidney was altered leading to possible redox disruption of this tissue with no alterations in offspring. Finally, the genomic damage was exacerbated in both male and female pups. In conclusion, low-dose MeHg exposure and retinyl palmitate supplementation during gestation and lactation produced a potentiated pro-oxidant effect, which was tissue-specific. Although this is a pre-clinical approach, we recommend precaution for pregnant women regarding food consumption, and we encourage more epidemiological studies to assess possible modulations effects of MeHg-VitA co-administration at safe or inadvertently used doses in humans, which may be related to specific pathologies in mothers and their children

Micronucleus frequency and exposure to chemical mixtures in three Colombian mining populations

La industria minera colombiana ha experimentado un crecimiento significativo. Dependiendo de la escala y del mineral extraído, se generan mezclas químicas complejas que impactan la salud de las poblaciones ocupacionalmente expuestas y de las comunidades cercanas a los proyectos mineros. Cada vez hay más evidencias que sugieren que la inestabilidad cromosómica (CIN) es un vínculo importante entre el desarrollo de ciertas enfermedades y la exposición a mezclas complejas. Para comprender mejor los efectos de la exposición a mezclas complejas realizamos un estudio de biomonitorización en 407 individuos sanos de cuatro zonas: tres situadas en municipios que explotan sistemas mineros de diferente escala y una zona de referencia sin actividad minera. Se analizaron sistemas de minería a gran, mediana y pequeña escala en Montelíbano (Córdoba), minería artesanal y de pequeña escala (MAPE) en Nechí (Antioquia) y un sistema de minería cerrada en Aranzazu (Caldas). El área de referencia sin actividad minera se estableció en Montería (Córdoba). La ICP-MS midió la exposición multielemental en el cabello, y la NIC se evaluó mediante la técnica de micronúcleos en bloque de citocinesis (MNBN). La exposición a mezclas de elementos químicos fue comparable en trabajadores y residentes de las zonas mineras, pero significativamente superior en comparación con los individuos de referencia. En Montelíbano, el aumento de las frecuencias de MNBN se asoció con la exposición combinada a Se, Hg, Mn, Pb y Mg. Este patrón distintivo difirió significativamente de otras áreas. Específicamente, en Nechí, Cr, Ni, Hg, Se, y Mg emergieron como los principales contribuyentes a las frecuencias elevadas de MNBN. Por el contrario, una combinación de Hg y Ni desempeñó un papel en el aumento de MNBN en Aranzazu. Curiosamente, el Se se correlacionó consistentemente con el aumento de las frecuencias de MNBN en todas las áreas mineras activas. Los elementos químicos en Montelíbano muestran un rango más amplio en comparación con otras zonas mineras, reflejando las características de la minería de alto impacto y a gran escala en la zona. Esta investigación proporciona información valiosa sobre los efectos de la exposición a mezclas químicas, subrayando la importancia de emplear este enfoque en la evaluación del riesgo de las comunidades, especialmente las de las zonas residenciales. © 2023 Los autoresThe Colombian mining industry has witnessed significant growth. Depending on the scale and mineral extracted, complex chemical mixtures are generated, impacting the health of occupationally exposed populations and communities near mining projects. Increasing evidence suggests that chromosomal instability (CIN) is an important link between the development of certain diseases and exposure to complex mixtures. To better understand the effects of exposure to complex mixtures we performed a biomonitoring study on 407 healthy individuals from four areas: three located in municipalities exploiting different-scale mining systems and a reference area with no mining activity. Large, medium, and small-scale mining systems were analyzed in Montelibano (Córdoba), artisanal and small-scale mining (ASGM) in Nechí (Antioquia), and a closed mining system in Aranzazu (Caldas). The reference area with no mining activity was established in Montería (Córdoba). ICP-MS measured multi-elemental exposure in hair, and CIN was evaluated using the cytokinesis-block micronucleus technique (MNBN). Exposure to mixtures of chemical elements was comparable in workers and residents of the mining areas but significantly higher compared to reference individuals. In Montelibano, increased MNBN frequencies were associated with combined exposure to Se, Hg, Mn, Pb, and Mg. This distinct pattern significantly differed from other areas. Specifically, in Nechí, Cr, Ni, Hg, Se, and Mg emerged as the primary contributors to elevated frequencies of MNBN. In contrast, a combination of Hg and Ni played a role in increasing MNBN in Aranzazu. Interestingly, Se consistently correlated with increased MNBN frequencies across all active mining areas. Chemical elements in Montelibano exhibit a broader range compared to other mining zones, reflecting the characteristics of the high-impact and large-scale mining in the area. This research provides valuable insights into the effects of exposure to chemical mixtures, underscoring the importance of employing this approach in the risk assessment of communities, especially those from residential areas. © 2023 The Author

Gestión del conocimiento. Perspectiva multidisciplinaria. Volumen 17

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 17 de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro es una publicación internacional, seriada, continua, arbitrada, de acceso abierto a todas las áreas del conocimiento, orientada a contribuir con procesos de gestión del conocimiento científico, tecnológico y humanístico. Con esta colección, se aspira contribuir con el cultivo, la comprensión, la recopilación y la apropiación social del conocimiento en cuanto a patrimonio intangible de la humanidad, con el propósito de hacer aportes con la transformación de las relaciones socioculturales que sustentan la construcción social de los saberes y su reconocimiento como bien público

Estimación de la función de sobrevivencia con datos de riesgos en competencia bivariados dependientes: un estudio comparativo utilizando el estimador cópula gráfico

En esta investigación el objetivo central es estimar la función de sobrevivencia con datos de riesgos competitivos bivariados dependientes. Para estimar esta función para el tiempo mínimo de falla teniendo en cuenta la dependencia verdadera entre estos tiempos bivariados, se utilizó un modelo cópula mediante el estimador cópula gráfico, también se estimó la función de sobrevivencia como en la metodología tradicional asumiendo independencia entre los tiempos de falla. Estas estimaciones se compararon con la función de sobrevivencia verdadera, para ello se hacen simulaciones mediante las cuales se obtuvieron tiempos bivariados asociados a diferentes distribuciones Weibull y Lognormales, cada escenario de simulación contiene 6 situaciones diferentes, asociadas a 6 valores del parámetro de dependencia entre los tiempos de cada modo de falla. Se concluye acerca de la bondad del ajuste de los dos estimadores. También se estudian las marginales con los dos estimadores. En general se encontró, que el estimador cópula gráfico estima mejor la función de sobrevivencia en comparación al estimador tradicional que asume independencia. / Abstract: In this research the main objective is to estimate the function survival with data competing risks bivariate dependent. To estimate this function for the minimum time of failure taking into account the true dependence between these times was used copula model through of the copula graphic estimator, also estimated the survival function as in the traditional methodology that assumes independence between failure times. These estimates were compared with the true survival function, for this are make simulations which were obtained at different times associated to distributions Weibull and lognormal bivariate, each simulation scenario contains 6 different situations, associated with 6 values of the parameter of dependence between the times of each failure mode. We conclude about the goodness of fit of the two estimators. Also are studied the marginal with the two estimators. In general it was found that the copula graphic estimator estimated better the survival function compared to the traditional estimator than assumes independence.Maestrí

Intervalos de confianza Jackknife para cuantiles en muestreo con probabilidades desiguales

Se considera la estimación de cuantiles en poblaciones finitas mediante la técnica jackknife. Se emplea un estimador jackknife de varianza para muestreo con probabilidades desiguales que funciona mejor que el estimador jackknife clásico. La calidad del intervalo de confianza hallado se demuestra vía simulación. El intervalo de confianza propuesto mostró probabilidades de cobertura cercanas al nivel de confianza nominal, así como longitudes promedio y varianzas mucho menores que las longitudes promedio y las varianzas de los intervalos empleando la metodología jackknife tradicional.We consider the estimation of quantiles in finite population susing the jackknife technique. We use a jackknife variance estimator for unequal probability sampling that works better than the classical jackknife estimator. The quality of the confidence interval found is demonstrated via simulation. The proposed confidence interval showed coverage probabilities that were close to the nominal confidence level, and mean lengths and variances much smaller than the mean lengths and variances of the intervals using the traditional jackknife methodology

Comparación entre riesgos competitivos vía el estimador cópula-gráfico Comparison between Competing Risks via the Copula-Graphic Estimator

En riesgos competitivos, el problema de identificabilidad asociado a la dependencia entre los modos de falla, se puede resolver utilizando el estimador cópula-gráfico que asume la forma de la cópula conocida. En este trabajo se compara, mediante simulación, este estimador para un modelo de riesgos competitivos dependientes con el estimador tradicional que asume independencia. Se muestra que ignorar la dependencia puede causar subestimación significativa de la función de confiabilidad. Se ilustra la temática con un ejemplo y se visualiza a futuro la posible utilidad del estimador cópula-gráfico en confiabilidad industrial para predecir en experimentos acelerados.The identifiability problem in competing risks associated to the dependence measure between the failure modes, can be solved by means of the copula-graphic estimator which assumes the copula function known. This paper compares, through a simulation study, the copula-graphic estimator for a dependent competing risks model with the traditional one under the assumption of independence. It is shown that a significant subestimation of the reliability function can be made when the dependence is not taken into account. An example ilustrates this point and as a future work it is seen the possibility of using copula-graphic in industrial reliability to predict in accelerated life tests

Efectos de la coadministración de metilmercurio y palmitato de retinol en ratas durante el embarazo y la lactancia materna: parámetros metabólicos y redox en las madres y sus crías

Ubiquitous low-dose methylmercury (MeHg) exposure through an increased fish consumption represents a global public health problem, especially among pregnant women. A plethora of micronutrients presented in fish affects MeHg uptake/distribution, but limited data is available. Vitamin A (VitA), another fish micronutrient is used in nutritional supplementation, especially during pregnancy. However, there is no information about the health effects arising from their combined exposure. Therefore, the present study aimed to examine the effects of both MeHg and retinyl palmitate administered on pregnant and lactating rats in metabolic and redox parameters from dams and their offspring. Thirty Wistar female rats were orally supplemented with MeHg (0,5 mg/kg/day) and retinyl palmitate (7500 µg RAE/kg/day) via gavage, either individually or in combination from the gestational day 0 to weaning. For dams (150 days old) and their offspring (31 days old), glycogen accumulation (hepatic and cardiac) and retinoid contents (plasma and liver) were analyzed. Hg deposition in liver tissue was quantified. Redox parameters (liver, kidney, and heart) were evaluated for both animals. Cytogenetic damage was analyzed with micronucleus test. Our results showed no general toxic or metabolic alterations in dams and their offspring by MeHg-VitA coadministration during pregnancy and lactation. However, increased lipoperoxidation in maternal liver and a disrupted pro-oxidant response in the heart of male pups was encountered, with apparently no particular effects in the antioxidant response in female offspring. GST activity in dam kidney was altered leading to possible redox disruption of this tissue with no alterations in offspring. Finally, the genomic damage was exacerbated in both male and female pups. In conclusion, low-dose MeHg exposure and retinyl palmitate supplementation during gestation and lactation produced a potentiated pro-oxidant effect, which was tissue-specific. Although this is a pre-clinical approach, we recommend precaution for pregnant women regarding food consumption, and we encourage more epidemiological studies to assess possible modulations effects of MeHg-VitA co- administration at safe or inadvertently used doses in humans, which may be related to specific pathologies in mothers and their children.Exposición ubicua a baja dosis de metilmercurio (mehg) a través de un aumento de los peces el consumo representa un problema de salud pública mundial, especialmente entre las embarazadas mujeres. Una gran cantidad de micronutrientes presentados en pescado afecta mehg captación / distribución, pero se dispone de datos limitados. Vitamina a (vita), otro pescado. El micronutriente se usa en suplementos nutricionales, especialmente durante el embarazo. Sin embargo, no hay información sobre los efectos en la salud que surgen de su exposición combinada. Por lo tanto, el presente estudio tuvo como objetivo examinar los efectos de mehg y palmitato de retinilo administrados en ratas gestantes y lactantes en parámetros metabólicos y redox de las represas y su descendencia. Treinta wistar ratas hembra fueron suplementadas oralmente con mehg (0,5 mg / kg / día) y retinilo palmitato (7500 µg rae / kg / día) por sonda, individualmente o en combinación desde el día gestacional 0 hasta el destete. Para las presas (150 días de antigüedad) y sus crías. (31 días de edad), acumulación de glucógeno (hepático y cardíaco) y retinoides. (plasma e hígado) fueron analizados. Se cuantificó la deposición de hg en tejido hepático. Se evaluaron los parámetros redox (hígado, riñón y corazón) para ambos animales. El daño citogenético se analizó con prueba de micronúcleo. Nuestros resultados no mostraron alteraciones generales tóxicas o metabólicas en las madres y su descendencia por coadministración de mehg-vita durante el embarazo y la lactancia. Sin embargo, aumentó lipoperoxidación en el hígado materno y una respuesta prooxidante interrumpida en el corazón. De cachorros machos, aparentemente sin efectos particulares en la respuesta antioxidante en la descendencia femenina. Se alteró la actividad de gst en riñón de la presa. Llevando a una posible alteración redox de este tejido sin alteraciones en la descendencia. Finalmente, el daño genómico se exacerbó tanto en cachorros machos como hembras. En conclusión, la exposición a baja dosis de mehg y la suplementación con palmitato de retinilo durante la gestación y la lactancia produjeron un efecto prooxidante potenciado, que fue tejido específico, aunque este es un enfoque preclínico, recomendamos precaución. Para las mujeres embarazadas en relación con el consumo de alimentos, y animamos estudios epidemiológicos para evaluar los posibles efectos moduladores de la co-mehg-vita la administración a dosis seguras o inadvertidamente utilizadas en humanos, que pueden ser relacionados con patologías específicas en madres y sus hijo

Genetic Instability among Hitnü People Living in Colombian Crude-Oil Exploitation Areas

Oil exploitation, drilling, transportation, and processing in refineries produces a complex mixture of chemical compounds, including polycyclic aromatic hydrocarbons (PAHs), which may affect the health of populations living in the zone of influence of mining activities (PZOI). Thus, to better understand the effects of oil exploitation activities on cytogenetic endpoint frequency, we conducted a biomonitoring study in the Hitnü indigenous populations from eastern Colombia by using the cytokinesis micronucleus cytome assay (CBMN-cyt). PAH exposure was also measured by determine urine 1-hydroxypyrene (1-OHP) using HPLC. We also evaluated the relationship between DNA damage and 1-OHP levels in the oil exploitation area, as well as the modulating effects of community health factors, such as Chagas infection; nutritional status; and consumption of traditional hallucinogens, tobacco, and wine from traditional palms. The frequencies of the CBMN-cyt assay parameters were comparable between PZOI and Hitnü populations outside the zone of influence of mining activities (POZOI); however, a non-significant incremental trend among individuals from the PZOI for most of the DNA damage parameters was also observed. In agreement with these observations, levels of 1-OHP were also identified as a risk factor for increased MN frequency (PR = 1.20) compared to POZOI (PR = 0.7). Proximity to oil exploitation areas also constituted a risk factor for elevated frequencies of nucleoplasmic bridges (NPBs) and APOP-type cell death. Our results suggest that genetic instability and its potential effects among Hitnü individuals from PZOI and POZOI could be modulated by the combination of multiple factors, including the levels of 1-OHP in urine, malnutrition, and some traditional consumption practices