Actividad de butirilcolinesterasa y micronúcleos en trabajadores agrícolas expuestos a mezclas de plaguicidas / Butyrylcholinesterase activity and micronuclei in agricultural workers exposed to pesticide mixtures

Los plaguicidas son xenobióticos de gran utilidad para el control de las plagas y su uso es una realidad para obtener mayor rendimiento en los cultivos. Sin embargo, tienen el riesgo de producir toxicidad, por lo que es necesario el monitoreo biológico de los trabajadores expuestos a estas sustancias. El objetivo de este estudio fue evaluar la actividad de la butirilcolinesterasa (BCh) y la presencia de micronúcleos (MN) en trabajadores expuestos a mezclas de plaguicidas en el municipio Urdaneta, estado Lara. Participaron 82 individuos de sexo masculino, 41 expuestos (GE) y 41 no expuestos (GNE), la determinación de la butirilcolinesterasa se realizó en muestras de sangre, y la de micronúcleos en muestras epiteliales de la mucosa bucal. Los resultados fueron presentados empleando estadísticos descriptivos, frecuencias absolutas y porcentajes, utilizando el paquete libre PAST v.2.04. Los valores de actividad de BCh en el GE (3528,75+/- 1162,45U/L) mostraron diferencias estadísticamente significativas (P<0,001) en relación al GNE (5764,41+/-1641,43U/L). La frecuencia de MN presentó mayor mediana en el GE respecto al GNE (3,09 vs 0,73) con una diferencia significativa (P<0,001). Al asociar el tiempo de exposición con la actividad de BCh y la frecuencia de MN, se presentó una correlación negativa con la actividad de BCh y una correlación positiva con los MN, estadísticamente significativas P<0,001 y P<0,05. Los hallazgos obtenidos reflejan que los plaguicidas fueron utilizados en forma de mezclas siendo los más usados: organofosforados, carbamatos y piretroides produciendo modificaciones en los valores de actividad de BCh y la frecuencia de MN en individuos expuestos a plaguicidas(AU)

Pesticides are xenobiotics, useful in controlling pests and their use ileads to greater crop yields. However, they carry a risk of toxicity so biological monitoring of exposed workers is necessary. The aim of this study was to evaluate the cholinesterase activity and the presence of micronuclei in workers exposed to pesticide mixtures in the town of Urdaneta, Lara. Eighty-two workers participated, 41 exposed (EG) and 41 nonexposed (NEG), all of whome were male. Blood samples were obtained for the determination of butyrylcholinesterase (BCh); buccal mucosal epithelial samples were obtained for micronuclei (MN) sampline. The results were presented as descriptive statistics, absolute frequencies and percentages, using the PAST v.2.04 a free online software package. The BCh activity values in the EG (3528.75+/-1162.45U/L) showed statistically significant differences (P<0.001) in relation to the UEG (5764.41 +/- 1641.43U/L). Median MN frequency was highest in the EG compared to UEG (3.09vs 0.73), a significant difference (P<0.001). By associating exposure time with BCh activity and MN frequency, a negative correlation was found with BCh activity and a positive correlation with MN, both statistically significant (P<0.001 and P<0.05, respectively). The results suggested pesticide mixtures were the most often used: organophosphates, carbamates and pyrethroids produced changes in the activity values of BCh and the frequency of MN in individuals exposed to pesticides(AU)

Micronúcleos: biomarcador de genotoxicidad en expuestos a plaguicidas / Micronucleus: genotoxicity biomarker in exposed to pesticides

El uso de plaguicidas a nivel mundial ha permitido el control efectivo de plagas, aumentando la productividad agrícola, forestal y ganadera. Sin embargo, muchas de estas sustancias químicas representan peligros potenciales para la salud humana, pudiendo provocar alteraciones en el material genético y el posible desarrollo de algunos tipos de tumores. En consecuencia, se ha hecho necesario la búsqueda de métodos que permitan cuantificar el grado de inestabilidad que estos productos puedan causar al material genético, entre ellos, el ensayo de micronúcleos (MN). Éste se basa en la detección y cuantificación de cuerpos citoplasmáticos semejantes al núcleo celular, cuyo origen se deriva de cromosomas, o fragmentos de éstos, que no se integran al núcleo durante la metafase, lo cual puede suceder de manera espontánea o por la acción de agentes genotóxicos. El propósito del artículo es presentar una revisión de 33 publicaciones en el período 2000- 2013 a nivel mundial en individuos expuestos a plaguicidas, de los cuales 16 utilizaron el ensayo en cultivos de linfocitos en sangre, 13 en células epiteliales bucales y 4 en ambas técnicas. Aun cuando existen discrepancias entre los autores en relación con la frecuencia de MN y diversos factores, este ensayo constituye una herramienta de monitoreo que permite obtener resultados rápidos y de gran sensibilidad para detectar daño en el ADN, y de esta forma, poder tomar medidas para el control de los riesgos genéticos asociados con la exposición a agentes tóxicos como los plaguicidas.

Pesticides use has allowed effective control of pests worldwide, increasing agricultural, forestry and livestock productivity. However, many of these chemicals pose potential risks to human health and it can cause alterations in the genetic material, and the possible development of some types of tumors. Consequently, it has become necessary to search for methods to quantify the degree of instability that these products can produce in the genetic material, including the micronucleus (MN) test. This is based on the detection and quantification of cytoplasmic bodies similar to the cell nucleus, whose origin is derived from chromosomes or fragments that are not integrated to the core during metaphase, which could occur spontaneously or by the action of genotoxic agents. The purpose of this article is to present a review of 33 publications in the period 2000-2013 worldwide in individuals exposed to pesticides, of which 16 used the test in cultured lymphocytes in the blood, 13 in buccal epithelial cells, and 4 in both techniques. Even, when there are discrepancies among the authors regarding the frequency of MN and various factors, this test is a monitoring tool that provides fast results and high sensitivity for detecting DNA damage and, thus, been able to take action for the control of genetic risks associated with exposure to toxic agents such as pesticides..

Regulation of calbindin-D(28k) expression by Msx2 in the dental epithelium.

Amelogenesis involves the coordinated expression of a set of molecules that includes enamel matrix proteins and calcium-binding proteins. Msx2 is a member of the divergent homeobox gene family and is instrumental in dental morphogenesis and biomineralization. This study focused on an EF-hand calcium-binding protein, calbindin-D(28k), which is highly expressed in dental epithelium. In vivo data showed that calbindin-D(28k) levels were higher in ameloblasts from Msx2(+/-) mice than Msx2(+/+) mice. Consistent with this finding, calbindin-D(28k) distribution was affected in transgenic mice with ectopic expression in root epithelium in rests of Malassez in Msx2(+/-) and more clearly in Msx2(-/-) mice. In accordance with these in vivo data, calbindin-D(28k) protein and mRNA levels were decreased in LS8 ameloblast-like cells by exogenous Msx2 overexpression. Furthermore, calbindin-D(28k) promoter activity (nt-1075/+34) was specifically diminished in the presence of Msx2 overexpression, showing that Msx2 behave as a transcriptional repressor for calbindin-D(28k) gene expression. In conclusion, Msx2 may control the spatiotemporally restricted frame of calbindin-D(28k) production in the dental epithelium in relation to enamel mineralization, as previously shown for amelogenin.

Enamel protein regulation and dental and periodontal physiopathology in MSX2 mutant mice.

Signaling pathways that underlie postnatal dental and periodontal physiopathology are less studied than those of early tooth development. Members of the muscle segment homeobox gene (Msx) family encode homeoproteins that show functional redundancy during development and are known to be involved in epithelial-mesenchymal interactions that lead to crown morphogenesis and ameloblast cell differentiation. This study analyzed the MSX2 protein during mouse postnatal growth as well as in the adult. The analysis focused on enamel and periodontal defects and enamel proteins in Msx2-null mutant mice. In the epithelial lifecycle, the levels of MSX2 expression and enamel protein secretion were inversely related. Msx2+/- mice showed increased amelogenin expression, enamel thickness, and rod size. Msx2-/- mice displayed compound phenotypic characteristics of enamel defects, related to both enamel-specific gene mutations (amelogenin and enamelin) in isolated amelogenesis imperfecta, and cell-cell junction elements (laminin 5 and cytokeratin 5) in other syndromes. These effects were also related to ameloblast disappearance, which differed between incisors and molars. In Msx2-/- roots, Malassez cells formed giant islands that overexpressed amelogenin and ameloblastin that grew over months. Aberrant expression of enamel proteins is proposed to underlie the regional osteopetrosis and hyperproduction of cellular cementum. These enamel and periodontal phenotypes of Msx2 mutants constitute the first case report of structural and signaling defects associated with enamel protein overexpression in a postnatal context.

Physiological implications of DLX homeoproteins in enamel formation.

Tooth development is a complex process including successive stages of initiation, morphogenesis, and histogenesis. The role of the Dlx family of homeobox genes during the early stages of tooth development has been widely analyzed, while little data has been reported on their role in dental histogenesis. The expression pattern of Dlx2 has been described in the mouse incisor; an inverse linear relationship exists between the level of Dlx2 expression and enamel thickness, suggesting a role for Dlx2 in regulation of ameloblast differentiation and activity. In vitro data have revealed that DLX homeoproteins are able to regulate the expression of matrix proteins such as osteocalcin. The aim of the present study was to analyze the expression and function of Dlx genes during amelogenesis. Analysis of Dlx2/LacZ transgenic reporter mice, Dlx2 and Dlx1/Dlx2 null mutant mice, identified spatial variations in Dlx2 expression within molar tooth germs and suggests a role for Dlx2 in the organization of preameloblastic cells as a palisade in the labial region of molars. Later, during the secretory and maturation stages of amelogenesis, the expression pattern in molars was found to be similar to that described in incisors. The expression patterns of the other Dlx genes were examined in incisors and compared to Dlx2. Within the ameloblasts Dlx3 and Dlx6 are expressed constantly throughout presecretory, secretory, and maturation stages; during the secretory phase when Dlx2 is transitorily switched off, Dlx1 expression is upregulated. These data suggest a role for DLX homeoproteins in the morphological control of enamel. Sequence analysis of the amelogenin gene promoter revealed five potential responsive elements for DLX proteins that are shown to be functional for DLX2. Regulation of amelogenin in ameloblasts may be one method by which DLX homeoproteins may control enamel formation. To conclude, this study establishes supplementary functions of Dlx family members during tooth development: the participation in establishment of dental epithelial functional organization and the control of enamel morphogenesis via regulation of amelogenin expression.