Ensayo estandarizado (ISO 17512) de comportamiento de evitación de suelos contaminados. Efecto del pesticida dimetoato sobre la lombriz de tierra Aporrectodea caliginosa / Standardized avoidance test (ISO 17512) for contaminated soils. Effect of the pesticide dimethoate on the earthworm Aporrectodea caliginosa

La creciente preocupación por el bienestar animal ha propiciado el rechazo por parte de la sociedad a la utilización de animales en experimentación. Por este motivo, actualmente se están desarrollando métodos alternativos que cumplan con el principio de las 3Rs (reemplazar, reutilizar y refinar). Muchos de estos métodos se basan en la utilización de organismos inferiores, como las lombrices de tierra. El presente estudio desarrolla el ensayo estandarizado de la Organización Internacional de Normalización (ISO) 17512-1:2008, en el que se evalúa la toxicidad producida por el plaguicida organofosforado dimetoato en el suelo, utilizando la capacidad de repulsión o evitación que presentan las lombrices de tierra pertenecientes a la especie Aporrectodea caliginosa. Las concentraciones seleccionadas han sido 0,06, 0,3 y 1,5 mg/kg de suelo, ensayada cada una de ellas por triplicado, empleando 10 lombrices por cada réplica. Los resultados reflejan la capacidad de las lombrices de tierra de la especie Aporrectodea caliginosa para evitar suelos contaminados con el formulado comercial de dimetoato. Por otra parte, se confirma la tendencia de las lombrices a evitar el suelo contaminado a medida que aumenta la concentración de plaguicida ensayada, con significación estadística a la dosis más alta empleada (1,5 mg/kg). (AU)

The increasing concern about animal wellness has induced the repulse of society to the use of animals in research. For this reason, alternative methods which comply with the 3Rs principle (Replace, Reuse and Refine) are currently being developed. Many of these methods are based on the use of lower organisms on the evolutionary scale, such as earthworms. The present study develops the standardized test of the International Organization of Standardization (ISO) 17512-1:2008, in which the toxicity produced by the pesticide organophosphate dimethoate in the soil is evaluated, using the capacity of repulsion or avoidance that presents the earthworms Aporrectodea caliginosa. The assayed concentrations were 0.06, 0.3 and 1.5 mg/kg of soil, each one tested in triplicated, using 10 earthworms for each repetition. The results reflect the ability of earthworms of the species Aporrectodea calliginosa to avoid soils contaminated with the commercial formulation of dimethoate. On the other hand, the tendency of worms to avoid contaminated soils is confirmed as the concentration of pesticide increases, with statistical significance at the highest concentration used (1.5 mg/kg). (AU)

Ensayo estandarizado (ISO 17512) de comportamiento de evitación de suelos contaminados II. Respuesta de distintos biomarcadores tras la exposición a dimetoato en la lombriz de tierra Aporrectodea caliginosa / Standardized avoidance test (ISO 17512) for contaminated soils II. Response of different biomarkers after exposure to dimethoate in earthworm Aporrectodea caliginosa

En la primera parte del presente estudio, publicado en 2021, se mostraron los resultados obtenidos al aplicar el ensayo estandarizado de la Organización Internacional de Normalización (ISO) 17512-1:2008. En dicho trabajo se evaluó la toxicidad producida por el plaguicida organofosforado dimetoato en el suelo, utilizando la capacidad de repulsión o evitación que presentan las lombrices de tierra de la especie Aporrectodea caliginosa. En esta segunda parte, para evaluar los efectos subletales producidos por el dimetoato sobre las lombrices, se han determinado como biomarcadores la actividad de la enzima acetilcolinesterasa (AChE, cuya inhibición es el principal mecanismo de acción de este tipo de compuestos) y la actividad glutatión S-transferasa (GST, que comúnmente se activa como mecanismo de detoxificación de plaguicidas). Las concentraciones seleccionadas han sido 0,06, 0,3 y 1,5 mg/kg de suelo, ensayada cada una de ellas por triplicado, empleando 10 lombrices por cada réplica.La actividad AChE se inhibió significativamente en la exposición a las tres concentraciones empleadas. No se ha producido aumento de la actividad GST que, por el contrario, aparece significativamente inhibida a la concentración más alta de plaguicida ensayada. La falta de una inducción de la actividad GST puede deberse a que el mecanismo de detoxificación no se ha puesto en marcha por el corto tiempo de exposición al plaguicida. Estos resultados reflejan la sensibilidad de la AChE como biomarcador de la contaminación de los suelos con organofosforados. (AU)

In the first part of this study, published in 2021, the results obtained when applying the standardized test of the International Organization of Standardization (ISO) 17512-1:2008 were shown. In this study, the toxicity produced by the pesticide organophosphate dimethoate in the soil was evaluated, using the capacity of repulsion or avoidance that presents the earthworms Aporrectodea caliginosa. To evaluate the sublethal effects produced by dimethoate on worms, the activities of the acetylcholinesterase enzyme (AChE, the inhibition of which is the main mechanism of action of this type of compound) and glutathione S-transferase enzyme (GST, which is commonly activated as a pesticide detoxification mechanism) have been determined. The commercial product called DIMAFID40, whose active substance is the organophosphate pesticide dimethoate, was used. The selected concentrations were 0.06, 0.3 and 1.5 mg / kg of soil, each one tested in triplicate, using 10 worms per replicate.The AChE activity was significantly inhibited after exposure to the three assayed concentrations. With respect to GST activity, it was not increased but significantly inhibited after exposition to the highest concentration of pesticide. The non-appearance of an induction of GST activity may be due to the fact that the detoxification mechanism has not been started because the time of exposure to the pesticide has been too short. These results reflect the sensibility of AChE as a biomarker of the contamination in soils with organophosphate. (AU)

Dietary administration of high doses of pterostilbene and quercetin to mice is not toxic.

The aim of this study is to evaluate possible harmful effects of high doses of t-pterostilbene (t-PTER) and quercetin (QUER) in Swiss mice. Mice were fed during 28 days at doses of 0, 30, 300, and 3000 mg/kg body weight/day of t-PTER, QUER, or a mixture of both, t-PTER + QUER, which are equivalent to 5, 50, and 500 times, respectively, the estimated mean human intake of these polyphenols (25 mg/day). Daily oral administration of QUER, t-PTER, or a mixture of both of them did not cause mortality during the experimental period. There were no differences in food and water consumption on sex. No significant body weight gain in the male or female groups was observed. Red blood cell number and the hematocrit increased after polyphenols administration compared to control groups. Biochemical parameters were not affected. Histopathological examination revealed no alterations in clinical signs or organ weight at any dose.

Antimicrobial susceptibility and pneumococcal serotypes.

The increase in antibiotic resistance and the possible changes in serotype prevalence as a consequence of a new conjugated vaccine have contributed to renewed interest in the study of pneumococcal serotypes and their antibiotic resistances. Spain still has one of the highest penicillin resistance rates, but in the past 4-5 years a slight decrease has been observed. The level of resistance has not increased either, 12.7% of the 11 165 isolates studied showed high-level penicillin resistance but 94% of these had an MIC of only 2 mg/L. Serotypes 6, 9, 14, 19 and 23 included 83% of the penicillin-resistant pneumococci; the remaining 17% belonged to 18 different serotypes. We analysed these minor penicillin-resistant serotypes in view of their potential increase following a possible child vaccination programme. Four of these serotypes (11, 15, 21 and 35) were the most prevalent, and among them serotype 15 was particularly frequent with >50% of its strains resistant. The effective control of these minor penicillin-resistant serotypes should be based on continuous surveillance of pneumococcal epidemiology.

Influence of remote substituents on the equatorial/axial selectivity in the monooxygenation of methylene C--H bonds of substituted cyclohexanes.

The reactivity of individual C--H bonds in the methyl(trifluoromethyl)dioxirane TFDO oxygenation of stereogenic methylene groups in conformationally homogeneous monosubstituted cyclohexanes (2) has been determined. The unexpectedly high occurrence of O-atom insertion into C--H(ax) bonds suggests an in plane trajectory attack in the oxygenation while the diastereoselectivity of the reaction is qualitatively interpreted on the basis of the distinct hyperconjugative stabilization by the substituent of diastereomeric transition states due to long-range through bond interactions.

C(5)H(7)O(2)(+) ions: the correlation between their thermochemistry in acidic solution and their chemistry in the gas phase

Each of a series of C(5)H(6)O(2) isomeric carboxylic acid and unsaturated lactones (1-7) was protonated in both concentrated sulfuric acid and trifluoromethanesulfonic acid. The thermally induced transformations of the protonated species were then studied over a temperature range of -30 to +160 degrees C. In the case of alpha,beta-unsaturated lactones, protonation took place on the carbonyl oxygen and gave the corresponding stable O-protonated species. Conversely, unconjugated lactones and acetylenic acid 7 were converted even at low temperature into the diprotonated ketoacid 8H(2)()o(+2)() by the acid-catalyzed addition of water to the C-protonated precursor. Upon being heated at 160 degrees C, this acid gave protonated 1,3-cyclopentanedione. In the absence of water, decarbonylation followed by polymerization was observed in lactones 4 and 5. The CIMS spectra of compounds 1-7 were recorded using methane, ammonia, and moist air as reagent gases to determine the correlation between the fragmentation routes in the gas phase and the transformations observed in solution. Ammonia and moist air enabled us to determine the different proton affinities of these compounds. The data obtained in strong acids were used to assign reasonable structures to the gas-phase ions.

Hyperconjugative Control by Remote Substituents of Diastereoselectivity in the Oxygenation of Hydrocarbons.

The oxidation of 2-substituted adamantanes (2) with TFDO (1) is reported. The data show a stereodifferentiation of the chemical environments induced by remote electron-withdrawing substituents which produces remarkable Z/E diastereoselectivity in the oxidation of the tertiary C(5)-H and C(7)-H bonds. The results show a bell-shaped correlation between the Z/E stereoselectivity and the substituent constant sigma(I), which is interpreted in terms of hyperconjugative stabilization of the diastereomeric transition states.