British Veterinary Journal最新文献

The incidence of bovine spongiform encephalopathy (BSE) in the UnitedKingdom is now declining at a significant rate, indicating that the 1988 ban on feeding ruminant-derived meat and bone meal to cattle is having the anticipated effect. The question now is whether or not BSE can be completely eradicated. At present there is no evidence of lateral or maternal transmission, the occurrence of which would complicate the eradication process. Eradication therefore seems to be achievable, especially now that meat and bone meal has been recently banned from the diets of all farmed animals in the UK. In this review the aetiological role of meat and bone meal in the causation of BSE is discussed together with the epidemiological data and the results of studies on genetic susceptibility. The controversial theories relating to the nature of the causal agent, and strain-typing studies on BSE agent, are described. Current information on pathogenesis and diagnosis is presented. The occurrence of BSE in cattle outside the United Kingdom, and BSE-related disease in species other than cattle is also discussed.

The pharmacokinetic behaviour of an amoxicillin/clavulanic acid combination(25 mg kg⁻¹), and both drugs alone (amoxicillin 20 mg kg⁻¹), clavulanic acid 5 mg kg⁻¹), was studied after intravenous (i.v.) administration of single doses to 10 goats. The objective was to determine whether there were differences in the plasma kinetics of these drugs when administered in combination or alone. The plasma concentration-time data were analysed by compartmental pharmacokinetics and non-compartmental methods. The disposition curves for both drugs alone and in combination were best described by a biexponential equation (two-compartment open model). The elimination half-lives of amoxicillin were 1.05±0.09 h alone and 1.13±0.19 h in combination, and those of clavulanic acid were 0.87±0.07 h and 0.85±0.09 h, respectively. The apparent volumes of distribution of amoxicillin and clavulanic acid were similar in the two treatments. Body clearances of amoxicillin were 0.12±0.01 l h⁻¹ · kg alone and 0.11±0.01 l h⁻¹ · kg in combination, and of clavulanic acid were 0.12±0.02 l h⁻¹ · kg alone and 0.12±0.01 l h⁻¹ · kg in combination with amoxicillin. The half-lives and body clearances of amoxicillin and clavulanic acid did not differ significantly when administered alone and in combination. It was concluded that the ix. administration of amoxicillin and ciavulanic acid as a combination product did not alter the disposition kinetics of either drug.

Two repetitive sequences (IpSdM and IpSdS) have been cloned andsequenced from the genome of Setaria digitata. When IpSdM (214 bp) and IpSdS (201 bp) were aligned, a high degree of homology (85%) was observed, indicating that they belong to the same family of repeats. IpSdM represents a complete repeating element while IpSdS consists of two partial repeating elements arranged in tandem. The elements are present in about 10 000 copies comprising 2.8% of the S. digilata genome. As a diagnostic probe IpSdM detects as little as 100 pg DNA of both S. digilata and S. labiato-papillosa. It can also detect a single microfilaria and a L₃ larva making it a valuable tool to monitor cattle and mosquito vector populations in the prevention of cerebrospinal nematodiasis.

Although it has long been thought that a retrovirus is the responsible agent for ovine pulmonary carcinoma (OPC), identification of a replicative viral agent has proven difficult. Recently, the genome of a new retrovirus, jaagsiekte sheep retrovirus (JSRV), found in the lung-was of affected sheep lung, has bee cloned and sequenced; characterization of this virus and its consistent presence in tumor cells argue for its role as the aetiologic agent of OPC. Analysis of the nucleic acid sequence of the JRSV genome, suggests a new class of retrovirus, one that is chimeric according to the morphological classification scheme used for retroviruses. The genome of this virus does not appear to contain an oncogene, and the mechanism by which it causes disease is still unknown. The presence of multiple copies of endogenous retroviruses related to JSRV in DNA of OPC-affected and unaffected sheep further complicates investigation of oncogenesis in OPC. This review examines the evidence for a retrovirus as the causative agent for OPC, with particular emphasis on the viruses studied to date. The significance of endogenous, JSRV-related sequences is considered. The mechanisms by which a retrovirus such as JSRV might induce lung tumours in sheep, and which of these are most likely, are discussed in light of these developments, as are the prospects for new means of diagnosis and treatment of this disease.

A reversed-phase high performance liquid chromatography technique hasbeen developed for the identification of taurine- and glycine-conjugated bile acids in the bile of preruminant goats. The mobile phase consisted of two solvents: acetonitrile (A) and 5 mm potassium phosphate buffer (pH 4.5) (B). Samples (10 μl) were eluted with a linear gradient in which acetonitrile was increased from 25 to 35%, and from 35 to 45%, at 10 min intervals. Flow rate was 1.0 ml min⁻¹, and bile acids were detected at 200 nm. This simple high resolution technique was highly reproducible, involved a minimum of straightforward sample treatment, and required a short chromatographic development time. The technique will be of use in the systematic identifications of bile acids in preruminants.