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Withdrawal Time (withdrawal + time)
Selected AbstractsKinetic analysis of oxytetracycline residues in Chinese mitten crab, Eriocheir sinensis, muscle following intramuscular administrationJOURNAL OF FISH DISEASES, Issue 8 2010Q Feng Abstract Crab culture is a very important economic industry in China. An epidemic of tremor disease of Chinese mitten crabs, Eriocheir sinensis, has become a serious problem in recent years. A spiroplasm has been proved to be the causative agent of this disease. Oxytetracycline (OTC) is used widely in aquaculture and was confirmed to be very effective against this pathogen. In this study, the distribution and depletion patterns of OTC in crab muscle were evaluated following single intramuscular doses of 2, 8 and 40 mg kg,1 body weight. OTC was detected with a validated HPLC method. Concentration,time profiles were well described by a three-compartment model with first-order absorption after a single dose of 8 and 40 mg kg,1. For comparison, a non-compartment model was employed. A withdrawal time of 48.29 and 55.92 days was suggested prior to consumption after receiving 8 and 40 mg kg,1. A recommended therapeutic dose of OTC in theory was calculated to be 36.37 mg kg,1. OTC was distributed well throughout the body. The elimination of OTC in muscle was slower compared with fish and other crustaceans. A dose of 40 mg kg,1 is suggested for practical use. [source] Long-lasting up-regulation of orexin receptor type 2 protein levels in the rat nucleus accumbens after chronic cocaine administrationJOURNAL OF NEUROCHEMISTRY, Issue 1 2007Guo-Chi Zhang Abstract Hypothalamic orexin (hypocretin) neurons project to the key structures of the limbic system and orexin receptors, both orexin receptor type 1 (OXR1) and type 2 (OXR2), are expressed in most limbic regions. Emerging evidence suggests that orexin is among important neurotransmitters that regulate addictive properties of drugs of abuse. In this study, we examined the effect of psychostimulant cocaine on orexin receptor protein abundance in the rat limbic system in vivo. Intermittent administration of cocaine (20 mg/kg, i.p., once daily for 5 days) caused a typical behavioral sensitization response to a challenge cocaine injection at a 14-day withdrawal period. Repeated cocaine administration at the same withdrawal time also increased OXR2 protein levels in the nucleus accumbens while repeated cocaine had no effect on OXR1 and orexin neuropeptide (both orexin-A and orexin-B) levels in this region. In contrast to the nucleus accumbens, OXR2 levels in the frontal cortex, the ventral tegmental area, the hippocampus, and the dorsal striatum (caudate putamen) were not altered by cocaine. Remarkably, the up-regulated OXR2 levels in the nucleus accumbens showed a long-lasting nature as it persisted up to 60 days after the discontinuation of repeated cocaine treatments. In contrast to chronic cocaine administration, an acute cocaine injection was insufficient to modify levels of any orexin receptor and peptide. Our data identify the up-regulation of OXR2 in the nucleus accumbens as an enduring molecular event that is correlated well with behavioral plasticity in response to chronic psychostimulant administration. This OXR2 up-regulation may reflect a key adaptation of limbic orexinergic transmission to chronic drug exposure and may thus be critical for the expression of motor plasticity. [source] Influence of enrofloxacin administration on the proteolytic and antioxidant enzyme activities of raw and cooked turkey productsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2005Irene Carreras Abstract The objective of this study was to assess the effect of enrofloxacin administration with and without withdrawal period on the quality of fresh meat and cooked products from turkey breasts. Cathepsin B and L activities were inactivated by the thermal process but were not affected by the presence of enrofloxacin. The level of enrofloxacin in samples without withdrawal time was higher than the regulatory maximum residue limit (MRL). The antioxidant enzymes glutathione peroxidase (GSHPx) and catalase (CAT) were affected by both the thermal process and the antibiotic residues in cooked meat. In no cases were differences found in superoxide dismutase (SOD) activity, supporting the theory that this enzyme could play a major role in preventing lipid oxidation of cooked meat. Enrofloxacin residues could contribute to an increase in the oxidative stress produced by thermal processing, as can be deduced by the reduction in GSHPx and CAT activities. Copyright © 2005 Society of Chemical Industry [source] Prophylaxis Against Hepatitis B Recurrence Posttransplantation Using Lamivudine and Individualized Low-Dose Hepatitis B ImmunoglobulinAMERICAN JOURNAL OF TRANSPLANTATION, Issue 8 2010L. Jiang Although the combination of lamivudine (LAM) and high-dose intravenous (IV) hepatitis B immunoglobulin (HBIG) is very effective in preventing hepatitis B virus (HBV) recurrence after liver transplantation (LT), the major limitation of this regimen is its high cost. A more cost-effective, convenient and widely accepted regimen is urgently needed. We evaluated the safety and efficacy of another strategy using LAM and individualized low-dose intramuscular (IM) HBIG. Between May 2002 and December 2009, a total of 254 adult patients undergoing LT for HBV-related benign end-stage liver diseases received this regimen in our center. The mean follow-up of these patients was 41.2 ± 22.7 months. Their 1-, 3- and 5-year survival rates were 85.3%, 77.4% and 76.4%, respectively, and 1-, 3- and 5-year HBV recurrence rates were 2.3%, 6.2% and 8.2%. Fourteen patients experienced posttransplant HBV recurrence. Pretransplant high viral load and posttransplant prednisone withdrawal time were observed to be associated with recurrence. In conclusion, combination therapy with LAM and individualized low-dose IM HBIG provides a safe and effective prophylaxis against HBV recurrence after LT at about 5% of the cost of conventional high-dose IV HBIG regimens. [source] Pharmacokinetics and tissue residues of marbofloxacin in crucian carp (Carassius auratus) after oral administrationAQUACULTURE RESEARCH, Issue 6 2009Yanlei Zhu Abstract Pharmacokinetics and residue elimination of marbofloxacin (MBF) were studied in crucian carp (Carassius auratus, 250±30 g) kept at two water temperatures of 15 and 25 °C. Marbofloxacin concentrations in plasma and tissues were analysed by means of high-performance liquid chromatography using an ultraviolet detector. The limits of detection were 0.02 ,g mL,1, 0.02 ,g g,1, 0.025 ,g g,1, 0.02 ,g g,1 and 0.025 ,g g,1 in plasma and muscle, skin, liver and kidney respectively. Fish were administered orally at a single dosage of 10 mg kg,1 body weight in the PK group. The data were fitted to two-compartment open models at both temperatures. At 15 °C, the absorption half-life () and distribution half-life (t1/2,) of the drug were 0.36 and 4.48 h respectively. The corresponding values at 25 °C were 0.23 and 0.87 h respectively. The elimination half-life (t1/2,) was 50.75 h at 15 °C and 25.05 h at 25 °C. The maximum MBF concentration (Cmax) differed little between 15 (6.43 ,g mL,1) and 25 °C (8.36 ,g mL,1). The time to peak concentration was 1.74 h at 15 °C and 0.78 h at 25 °C. The apparent volume of distribution (Vd/F) of MBF was estimated to be 1.36 and 0.87 L kg,1 at 15 and 25 °C respectively. The area under the concentration,time curve (AUC) was 301.80 ,g mL,1 h at 15 °C and 182.80 ,g mL,1 h at 25 °C. The total clearance of MBF was computed as 0.03 and 0.05 L h,1 kg,1 at 15 and 25 °C respectively. After repeated oral administration at a dosage of 10 mg kg,1 body weight per day for 3 days, the results showed that the elimination half-lives () of MBF from all tissues at 15 °C were longer than that at 25 °C. Therefore, water temperature is an important factor to be considered when deciding a reasonable withdrawal time. [source] Pharmacokinetics of oxolinic acid in gilthead sea bream, Sparus aurata L.JOURNAL OF FISH DISEASES, Issue 7 2002G Rigos This is the first study on the pharmacokinetic parameters of oxolinic acid (OA) in gilthead sea bream, Sparus aurata L. The kinetic profile of OA was studied after a single intravascular injection (20 mg kg,1) in 100 g fish at 20 °C. The distribution half-life (t1/2,) and the elimination half-life (t1/2,) of the drug were found to be short (0.51 and 12.60 h, respectively). The drug penetration from the plasma to the tissues was adequate as the apparent volume of distribution of the drug at steady-state (Vd(ss)) was found to be 2.11 L kg,1. The mean residence time (MRT) of OA was short (14.25 h) and the total clearance rate (ClT) of the drug was low (0.15 L kg,1 h,1). The bioavailability (F,%) of OA following oral administration (30 mg kg,1) was also low (14%). Maximum values were observed for muscle at 0.5 h after injection, with levels declining as with subsequent sampling. At the first two time points (0.5 and 1 h) plasma levels of OA were higher than muscle, however, the reverse was evident for subsequent samples. Following oral administration, highest muscle levels were found at 16 h and, with the exception of the 24-h sampling, muscle OA concentrations were higher than plasma at all time points. The fast elimination of OA suggests short withdrawal times with reference to human consumption of treated fish. [source] | ||||||||||