ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00448.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The recombinant DNA technology or DNA cloning permits the isolation, amplification, and precise manipulation of specific DNA fragments. This is generally accomplished by linking or recombining the desired DNA fragment with a DNA molecule, termed the vector, which is capable of directing the replication of itself in a suitable host cell and any DNA segment covalently attached to it. Using this and associated technologies, it is possible to produce large amounts of specific proteins and to modify cell types by introducing the genes for proteins that are otherwise absent. Moreover, it is now possible to construct variants of naturally‐occurring proteins with improved biological or physical propertie

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00449.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Following intravenous (i.v.) or intramuscular (i.m.) adminstration of sulphadimidine (SDM), the pharmacokinetics of SDM and N4‐acetylsulphadimidine (N4‐SDM) were studied in plasma of calves from the first day of life to the age of about 6 months. An obvious age dependency was observed for the elimination half‐life (t1/2) of SDM: the first day of life the t1/2 ranged between 13.5 and 17 h, and decreased in approximately 3 weeks to 4–6 h and remained constant from this time. The metabolite N4‐SDM, as a percentage of the total concentration of the sulphonamide measured in plasma of neonatal calves, ranged between 21.6 and 25.5% at the first day of life, declined in 3 weeks to approximately 12.8%, and at 5 till 9 weeks the final percentage was about 6.8%. Following administration of N4‐SDM, the elimination half‐life of N4‐SDM was 3 h in an 8‐day‐old calf declined to 1.4–1.7 h in 4‐week‐old calves, and was 0.9 h in calves older than 11 weeks. The percentage of SDM (a metabolite of N4‐SDM) in plasma increased with time after injection from 5.5 to 62.8% of the total sulphonamide plasma concentration. This value was age‐related. The total body clearance of N4‐SDM was three‐ to

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00450.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Median values for the minimum inhibitory concentrations (MIC) of tiamulin forMycoplasmaandAcholeplasmaisolated from ruminants were 0.05 μg/ml and 0.025 μg/ml, respectively. These values were close to the MIC values of tylosin and considerably lower than the respective values for spectinomycin, spiramycin and oxytetracyclin

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00451.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The persistence of chloramphenicol, cephacetrile, and clindamycin in the udders of dry cows was studied after drying‐off therapy with salts of these antibiotics suspended in conventional oil bases. Antibiotic activity was not found in dry udder secretions collected 3–5 days after treatment. After equivalent doses of encapsulated formulations of chloramphenicol were suspended in the same oil bases and infused at drying‐off, most of the drug remained bound within the microcapsules; chloramphenicol concentrations higher than 10 μg/ml secretion were maintained for 3–4 weeks, but upon release from the microcapsule, the free drug was very quickly absorbed from the udder. Microcapsulated formulations of cephacetrile and clindamycin were infused at drying‐off, suspended in the same type of oil base and at similar doses to the non‐capsulated preparations. The concentrations of free drug in the secretions remained constant over a period of 2–3 weeks, although total drug (bound and free) concentrations in the udder, which were much higher than free drug levels, were progressively and markedly reduced. It appeared that after infusion of the microcapsulated preparations of cephacetrile and clindamycin, rates of drug release from the depot were equal to the rates of absorption of free drug

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00452.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Tamethicillin (TAM) is a basic ester pro‐drug of methicillin (MET) which is converted in the body by non‐specific esterases to MET. Equal doses of MET and TAM were administered intramuscularly in a crossover trial involving four dairy cows. Acute mastitis was induced in each cow by infusing two quarters of the udder withEscherichia coliendotoxin 3 h before antibiotic administrat

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00453.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The pharmacokinetics of lidocaine in dogs were investigated following the intravenous and intramuscular administration of single doses of lidocaine hydrochloride. The mean elimination rate constant and the mean specific clearance determined for the intravenous portion of the study were 0.786 h‐1and 2.40 1/kg/h, respectively. Following intramuscular administration the mean absorption rate constant was 7.74 h‐1. Absorption was nearly complete as the percentage of an intramuscular dose absorbed averaged 91.9%. Concentrations of two N‐deethylated metabolites, determined following the administration of lidocaine suggest that monoethylglycinexylidide is eliminated rapidly while glycinexylidide is more slowly eliminated. The relative contribution of these metabolites to the therapeutic and toxic effects of lidocaine and the potential for glycinexylidide accumulation during lidocaine administration remain to be investi

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00454.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Oxytetracycline (OTC) was administered intravenously (i.v.) to 3‐and 12‐week‐old calves and lactating cows, and both i.v. and intramuscularly (i.m) to 14‐week‐old calves and non‐lactating cows. Concentrations of OTC were determined in plasma and were analysed kinetically. The pharmacokinetic parameters which were derived using the three‐compartment open model were inadequate to describe plasma drug levels in six out of the 23 animals treated i.v., and, therefore, model‐independent kinetic parameters were utilized for evaluating age‐dependent pharmacokinetics of OTC. In the 3‐week‐old calves, the total body clearance (Clb) was 0.0022 ml/min/kg, the total distribution volume (Vd area) was 2.48 l/kg, and the distribution volume of the central compartment (V1) was 0.56 l/kg. Mean values for Clb, Vd area, and V1in 3‐week‐old calves were two‐, three‐ and four‐fold greater, respectively, than the corresponding values in cows. Mean values of Clband Vd areafor the 12‐and 14‐week‐old calves were intermediate between the corresponding values in 3‐week‐old calves and cows. Dose and state of lactation did not affect the model‐independent parameters. The i.v. and i.m. data illustrated that the recommended dose levels of OTC in young calves should be twice those employed in cows for obtaining sim

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00455.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The pharmacokinetic parameters of erythromycin in foals were determined following intravenous administration of 5.0 mg/kg to animals aged 1, 3, 5 and 7 weeks. The distribution of the drug was described by a two‐compartment open model, and no significant differences were observed between coefficients on which the parameters were based. Pharmacokinetic values were also determined for four mares given 5.0 mg/kg intravenously and for six 10–12 week‐old foals given 20.0 mg/kg intravenously. The half‐life of erythromycin for all groups of animals (foals less than 7 weeks, mares, foals 10–12 weeks) was 1.0–1.1 h; the apparent volume of distribution was between 2.3 and 7.2 l/kg, and the clearance of the drug from the body was between 1.9 and 5.0 mg/kg/h. No drug could be detected in the serum following oral administration of 5.0 mg/kg erythromycin estolate; detectable levels were found for 5 h in mares given 12.5 mg/kg, and for 8 h in foals given 20.0 mg/kg orally. Peak levels in foals given the drug orally were 0.42 μg/ml at 120 min after administration. Foals given 10.0 mg/kg of erythromycin base intramuscularly had serum concentrations detectable 12 h later, the peak level achieved was 1.44 μg/ml serum 90 min after administration and concentrations exceeded 0.25 μg/ml for 6 h. In the mares the milk concentrations were approximately twice those in serum. Recommendations were made for drug dosage to be used in the treatment ofCorynebacterium equipneu

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00456.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00457.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY