Echinococcus granulosus is a parasitic cestode causing hydatidosis in intermediate hosts (human and herbivorous). Most symptoms of the disease occur by the pressure exerted on viscera by cysts that are formed upon ingestion of the parasite eggs excreted by definitive hosts (canines). Protoscoleces, the developmental form of the parasite infective to definitive hosts, are formed in the germinal nucleated layer of fertile hydatid cysts. For unknown reasons, some cysts are unable to produce protoscoleces (infertile hydatid cysts). In this study, analysis of DNA fragmentation using TUNEL and agarose gel electrophoresis showed higher levels of apoptosis in infertile cysts as compared to fertile cysts. Additionally, caspase 3 was detected both in fertile and infertile cysts; the activity of this enzyme was found to be higher in infertile cysts. We conclude that apoptosis may be involved in hydatid cyst infertility. This is the first report on the presence of programmed cell death in E. granulosus.
To ensure delivery of safe foods to consumers, withdrawal times for drugs must be respected according to the maximum residual limits established by regulatory agencies. Because of availability and price, feather meal is currently incorporated into animal feed as a protein source for farm species. Few data are available on residual drugs in feathers from treated animals. A depletion study was performed with laying hens treated intramuscularly with 5% enrofloxacin (Enromic) at 10 mg/kg body weight over 3 days. Thirty-three birds were treated and slaughtered at different times between 6 and 216 h after treatment; and samples of muscle plus skin, liver, kidney, and feathers were collected. High-performance liquid chromatography coupled with a tandem mass spectrometry method was validated before sample analysis to determine the decision limit, detection capability, recovery, and precision. Liver was the edible tissue with the slowest drug depletion. A withdrawal time of 6 days was calculated based on European Union maximum residual limits (100 microg/kg). A withdrawal time of 9 days was calculated based on Japan maximum residual limits (10 microg/kg). Enrofloxacin plus ciprofloxacin concentrations in feathers remained high through all sampling periods. Thus, feathers from treated animals should not be fed to food-producing animals.
To ensure delivery of safe animal products to consumers, the withdrawal time (WDT) of drugs must be respected. Property differences among pharmaceutical formulations, for the same drugs, can lead to differences in the WDTs estimation. The WDTs of four commercial formulations of enrofloxacin (ENRO) in broiler chickens, considering MRLs established by different countries, were studied. Two hundred-thirty-four broiler chicks were allotted among four groups; the formulations were orally administered daily with 10 mg/kg bw. After treatment, six chickens of each group and two controls were slaughtered daily until day 9 post-treatment. Samples of muscle and liver were collected, and analyzed using HPLC-MS-MS. The WDTs among formulations of ENRO showed differences of 24 and 48 h. Based on the European Community and Chile MRLs of 100 microg/kg (muscle) and 200 microg/kg (liver), the WDTs did not exceed 5 days. When Japan MRL was considered (10 microg/kg(,)), the WDTs increased up to 8 days. These results indicate that for WDTs determination, the differences among pharmaceutical formulations of a drug must be considered as well as the MRLs.
To ensure the delivery of safe animal products to consumers, withdrawal times (WDT) of drugs must be respected. Drugs administered in therapies can also reach nonedible tissues (for humans) such as feathers; this transfer is of concern as feather meal is used in diets of food producing animals, being this a possible source of residue contamination of final products for human consumption. WDTs of three flumequine formulations (10%, 80% premix powder and 20% solution) as well as the transfer of this drug into feathers were determined. One hundred and twenty broiler chickens were allocated into four experimental groups (36 birds each). Three of them were treated with 24 mg/kg bw orally for five consecutive days of each flumequine formulation, whereas one group remained untreated (12 birds as control group). After the treatment ended, six chickens of each experimental group and two controls were slaughtered daily for 6 days. Samples of muscle, liver and feathers were collected and analyzed by liquid chromatography tandem mass spectrometry (LC MS/MS). The WDTs showed differences between formulations. Flumequine concentrations found in feathers remained high during WDT and after this period, thus suggesting that the WDTs estimated for the pharmaceutical formulation of flumequine do not guarantee the absence of this drug in chicken nonedible tissues such as feathers.
Two groups of laying hens (each n=12) were administered 10 mg/kg enrofloxacin (ENRO) (group A) or 26.6 mg/kg flumequine (FLU) (group B) by gastric catheter daily for five consecutive days. A third group (n=6) was untreated controls. Eggs were collected from day one of treatment and up to 30 days after withdrawal of the drug. Egg white and yolk from each egg were separated, and ENRO, its metabolite ciprofloxacin (CIP) and FLU residues were analysed by a high-performance liquid chromatography method with fluorescence detection. The sum of ENRO and CIP was detectable in egg white on the first day of treatment in high-level concentrations (2007.7 μg/kg) and remained steady during administration. In egg yolk, residues were detectable at day one in lower concentrations (324.4 μg/kg), increasing to the end of treatment. After treatment, these residues decreased and were detectable up to day 8 in egg white, and day 10 in yolk. FLU residues during drug administration in white were detectable in high concentrations from day one to five (6788.4-6525.9 μg/kg), and in yolk, concentrations were lower during administration (629.6-853.9 μg/kg). After drug withdrawal, FLU residues remained longer in egg white (30 days) than in yolk (26 days). For both drugs, differences of concentrations between matrices were significant.
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