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The corpus luteum is an endocrine organ that exhibits extremely rapid growth, development, and regression during the course of each oestrus cycle. At the end of the luteal phase there is an orderly sequence of functional and structural changes in the corpus luteum connected with its regression. This article focuses on selected mechanisms controlling these changes. In these mechanisms, apart from central regulation, the essential role of local monocytes/macrophages and endothelial cells is stressed, as well as intercellular interactions. The research of the last years shows that corpus luteum regression is related to apoptosis. The functional changes that have been initialized by prostaglandin F2 are accompanied by the activation of immunological system cells, which while relieving cytokines work like local regulators in remodeling the corpus luteum. Consequently, metabolic changes, the disappearance of luteal tissue and the final expiration of progesterone production occur.
An analytical method for the simultaneous determination of tetracycline (TC), oxtetracycline (OTC), chlortetracycline (CTC) with their 4-epimers, and doxycycline (DC) in animal tissues has been developed and validated. The extraction of the analytes from biological matrice was carried out with a 0.02 M oxalic acid (pH=4.0). The samples were cleaned up by using a solid phase extraction procedure with polymeric cartridges. Chromatographic separation was achieved on a C 18 analytical column using a mobile phase consisting of acetonitrile, methanol and 0.02 M oxalic acid in gradient mode. Detection was carried out by UV detector at λ = 355 nm. The method has been validated according to the Commission Decision 2002/657/EC. The recoveries of the analytes from the spiked samples were 50%-80%. The decision limits (CCα) were from 110 to 125 µg/kg and the detection capabilities (CCß) were from 120 to 155 µg/kg, depending on the analytes. The prepared method was successfully verified in the National Residue Control Programme.
Intensive and massive pig production often contributes to excessive administration of antibacterials in veterinary medicine. The misuse and failures to follow the label directions of antibiotics, as well as withdrawal inadequacy, can lead to their residue occurrence in products of animal origin. The residue of drugs may result in many biological adverse effects and allergic reactions in consumers as well as the spread of drug-resistant bacteria and bacterial resistance acquisition. Consolidation of pig production requires ensuring adequate conditions of the maintenance of animals with high health conditions, consistent with the guidelines for animal welfare. At the same time, the control of antibiotics in animals is an important element providing the high quality of pigs breeding, as well as the protection of consumers. In residue monitoring programs, the primary material for the control of antibiotics presence in pigs are tissue samples, collected from animals at the slaughterhouse. However, post-mortem analysis does not give the opportunity of monitoring the usage of antibiotics on the farm during the breeding of animals. In ante mortem drug analysis blood can be used as a diagnostic biological matrix; however, blood sampling is connected with certain disadvantages for the animals and the staff responsible for material collection. The post-mortem detection and presence of antibiotic residues in pork tissues above MRL values very often lead to the recall and destruction of significant quantities of meat, which may contribute to economic losses. Therefore, a strong need to find and implement new methods for ante-mortem detection of antibiotics in animals exists, which minimize interference in animal welfare. The results of preliminary studies demonstrate that oral fluid seems to be an effective tool for monitoring the reasonable treatment and residue avoidance. It offers a cost-effective approach for the screening of large populations of animals. The method of oral fluid collection with cotton rope usage allows for the rapid sampling of material. In case of positive oral fluid ante-mortem analysis results, the slaughtering of animals can be delayed, which can bring the avoidance of costs connected with the non-compliant pig meat destruction.
A sensitive and selective LC method has been developed for the simultaneous determination of ten sulfonamides in muscles, after pre-column derivatization with fluorescamine. The whole procedure was validated in accordance with the Commission Decision 2002/657/EC. Detections capabilities (CCß) were from 125 µg/kg to 150 µg/kg, and recoveries ranged from 60% to 100% pending from analyte. The results demonstrate that the LC-FLD system is highly effective in analysing trace sulfonamides in muscles.
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