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La resitencia antielmintica (RA) a ivermectina (IVM) y otras lactonas macrocíclicas(LM) es un fenómeno mundialmente conocido . En ovinos, la administración de LMpor vía oral o intra-ruminal y en alta dosis ha logrado mejorar la eficacia frente aparásitos gastrointestinales (PGI), sin embargo no abundan aún experienciassimilares bovinos. El objetivo del presente ensayo fue evaluar la eficacia de IVM aalta dosis y por diferentes vías en terneros portadores de PGI resistentes a IVM enun engorde a corral comercial. De un total de 125 se seleccionaron 44 ternerosmachos, clínicamente sanos, los cuales fueron asignados a 4 grupos (n=11animales/grupo) que recibieron IVM a dosis estándar (0,2 mg/kg) y alta (1 mg/kg) ypor vía subcutánea e intra-ruminal. Previo al día del tratamiento (día ? 6) setomaron muestras de materia fecal para recuento de huevos de PGI por gramo ycoprocultivo; además se registró el peso individual de cada animal. El día deltratamiento fue considerado el día 0. En los días +14 y +27 se tomaron muestrasde materia fecal mientras que en el día +27 se registró nuevamente el peso. Lareducción en el recuento de huevos en materia fecal en el día +14 y +27 no mostró diferencias entre los grupos, dejando en evidencia la falta de eficacia de la droga aún en dosis quíntuple. No se observó diferencias en la ganancia diaria de peso entre los grupos. En el presente ensayo el uso de IVM en los diferentes grupos aalta dosis y por diferentes vías no obtuvo mejoras en los porcentajes de reducciónde huevos en materia fecal en bovinos portadores de PGI resistentes., Anthelmintic resistance to ivermectin and macrocyclic lactones (ML) is a worldwide spread problem. A high dose schedule of ML was effective against resistant nematodes in sheep, given oral and intra-ruminal. However, no enough data are available from cattle on this issue. Thus, the goal of this work was the efficacy assessment of IVM given at different doses and routes. To achieve this goal, 44 male feedlot calves, infected with IVM resistant nematodes, were assigned to four groups (n=11 calves per group). They received standard (0.2 mg/kg), or high doses (1 mg/kg) of IVM by subcutaneous or intra-ruminal routes. Before treatment (day -6), feces were sampled for eggs per gram counts (EPG) and copocultures; weight was also measured on this date. The treatments were administered on day 0. Later, on days +14 and +27, feces were re-sampled, and calves were weighed again just in the last date. Fecal egg count reductions showed no statistical differences between groups. This evidenced the lack of efficacy for IVM, even at a fivefold dose. Weight was neither different between groups. In conclusion, higher doses of IVM given by subcutaneous or intra-ruminal routes were insufficient to kill IVM-resistant nematodes in calves., Facultad de Ciencias Veterinarias

It is possible in principle to probe the many--atom potential surface using density functional theory (DFT). This will allow us to apply DFT to the Hamiltonian formulation of atomic motion in monatomic liquids [\textit{Phys. Rev. E} {\bf 56}, 4179 (1997)]. For a monatomic system, analysis of the potential surface is facilitated by the random and symmetric classification of potential energy valleys. Since the random valleys are numerically dominant and uniform in their macroscopic potential properties, only a few quenches are necessary to establish these properties. Here we describe an efficient technique for doing this. Quenches are done from easily generated "stochastic" configurations, in which the nuclei are distributed uniformly within a constraint limiting the closeness of approach. For metallic Na with atomic pair potential interactions, it is shown that quenches from stochastic configurations and quenches from equilibrium liquid Molecular Dynamics (MD) configurations produce statistically identical distributions of the structural potential energy. Again for metallic Na, it is shown that DFT quenches from stochastic configurations provide the parameters which calibrate the Hamiltonian. A statistical mechanical analysis shows how the underlying potential properties can be extracted from the distributions found in quenches from stochastic configurations.

La elección de un sistema de acceso venoso que proporcione una extracción sanguínea segura y unos resultados analíticos fiables en dicha muestra es de suma importancia en cualquier servicio de urgencias. El objetivo del estudio fue identificar los factores asociados a la hemólisis en muestras de sangre venosa, siendo las variables estudiadas el tipo de venopunción (con aguja y con catéter), el tipo de catéter (3 catéteres de 3 materiales diferentes) y el diámetro del catéter. La muestra se obtuvo de todos los pacientes que precisaron analítica de sangre en el Servicio de Urgencias del Hospital Virgen del Camino durante 34 días, recogidos en 3 períodos distintos (septiembre-noviembre). Se completó un total de 1.933 procedimientos. Se registró hemólisis positiva, determinada por los técnicos de laboratorio, en un 2% (7/348) de muestras obtenidas con aguja frente al 14% (222/1585) del catéter. Se observó un 8% (39/475) de hemólisis en las muestras extraídas mediante catéter Protectiv® de teflón, 18% (77/426) mediante Protectiv plus® de poliuretano y 15% (106/684) mediante BD-Nexiva® de vialón. El índice de hemólisis disminuyó al aumentar el calibre del catéter; así presentaron un 13% (115/867) los de 18G y un 15% (107/708) los de 20G. La combinación tipo de catéter y calibre mantiene los menores porcentajes de hemólisis para catéteres de teflón y diámetros altos de 18G con un 6% (19/301), menos de la mitad de hemólisis que los respectivos de poliuretano y menos de la tercera parte que los de vialón. The choice of a venous access system to provide safe blood collection and reliable analytical results for that sample is of paramount importance in any accident and emergency department. The objective of this study was to identify the factors associated with haemolysis in venous blood samples, where the variables studied were: type of venipuncture (needle and catheter), type of catheter (3 catheters of 3 different materials) and diameter of the catheter. The sample was obtained from all patients who required a blood test in the accident and emergencies department of the Virgen del Camino Hospital over 34 days, collected in 3 different periods (September-November), involving a total of 1.933 procedures. Positive haemolysis determined by laboratory technicians was found in 2% (7/348) of samples obtained by needle compared to 14% (222/1585) obtained by catheter. We observe an 8% (39/475) of haemolysis in the samples taken by protective Teflon® catheter, 18% (77/426) by Protectiv plus® polyurethane and 15% (106/684) by BD-Nexiva® Vialone. The haemolysis index fell with an increase in the size of the catheter, those of 18G showing 13% (115/867) and those of 20G showing 15% (107/708). The combination of catheter type and size maintains the smallest percentages of haemolysis in Teflon catheters and high diameters of 18G with 6% (19/301), less than half the haemolysis of the polyurethane catheters and a third of that for Vialone catheters respectively.

A new ternary Ir-Mn-Si phase with stoichiometry Mn3IrSi has been synthesized and found to crystallize in the cubic AlAu4-type structure, space group P213 with Z=4, which is an ordered form of the beta-Mn structure. The unit cell dimension was determined by x-ray powder diffraction to a=6.4973(3) Angstrom. In addition to the crystal structure, we have determined the magnetic structure and properties using superconducting quantum interference device magnetometry and Rietveld refinements of neutron powder diffraction data. A complex noncollinear magnetic structure is found, with magnetic moments of 2.97(4)u(B) at 10 K only on the Mn atoms. The crystal structure consists of a triangular network built up by Mn atoms, on which the moments are rotated 120degrees around the triangle axes. The magnetic unit cell is the same as the crystallographic and carries no net magnetic moment. The Neel temperature was determined to be 210 K. A first-principles study, based on density functional theory in a general noncollinear formulation, reproduces the experimental results with good agreement. The observed magnetic structure is argued to be the result of frustration of antiferromagnetic couplings by the triangular geometry.