Purification and characterisation of chicken liver monomeric glutathione peroxidase

1. A novel glutathione peroxidase, which is distinct from tetrameric glutathione peroxidase, was purified to homogeneity from a broiler chick liver cytosolic fraction using 5 different column chromatographic methods.

2. The enzyme in cytosol was separated from ‘classic’ tetrameric glutathione peroxidase and glutathione S‐transferases by DEAE‐Sephacel and Sephadex G‐100 chromatographies and further purified by Mono Q, hydroxylapatite and sulphobro‐mophthalein‐S‐glutathione‐agarose chromatographies.

3. The molecular weight of the purified enzyme determined by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis was 19,500 and that found by gel filtration chromatography was comparable. This indicates that the enzyme protein is a single polypeptide. The isoelectric point of the enzyme was determined as 7.0 by polyacrylamide gel isoelectric focusing.

4. The purified enzyme catalysed the reduction of hydrogen peroxide, cumene hydroperoxide, tert‐butyl hydroperoxide and linoleic acid hydroperoxide. Furthermore, it reduced phosphatidylcholine hydroperoxide in the absence of phospholi‐pase A2. The optimum pH for the enzyme reaction was 7.0. The antiserum against the purified enzyme reacted with the 19.5 kDa polypeptide in the liver cytosol of duck and quail.     

Soluble matrix of hen's eggshell extracts changes in vitro the rate of calcium carbonate precipitation and crystal morphology

1. Extra and intramineral eggshell matrix proteins were solubilised before and after demineralisation by sequential extractions using guanidine hydrochloride and EDTA.

2. The intramineral electrophoretic profile of SDS‐PAGE showed the presence of 80, 66, 43, 36 and 15 kDa bands with a predominance of a 17 kDa band. In the extramineral part, the major protein was the 15 kDa band.

3. The introduction of intramineral extract to a metastable solution of calcium carbonate delayed the rate of crystal growth. The delay in the rate of precipitation was elicited by a single fraction (MW 50–80 kDa), isolated by gel filtration chromatography, of eggshell extracts. Extramineral extracts had no effect.

4. Addition in vitro of intramineral eggshell extracts modified the morphology of calcite; the crystals aggregated and showed irregular surfaces.

5. These observations suggest that constituents of the eggshell matrix are involved in the control of calcite growth and crytallographic structure of the hen's eggshell.     

Evaluation of postoperative complications following elective surgeries of dogs and cats at private practices using computer records.

This study was designed to determine the frequency of postoperative complications following elective surgeries (castration, ovariohysterectomy, onychectomy) of dogs and cats from private practices and to evaluate the use of electronic medical records for this type of research. All elective surgeries performed during the study period at 5 private practices were included. The surgical techniques and materials used for each procedure were similar across practices, but the interpretation of "complication," the amount of detail recorded on the primary medical record, and the intensity of follow-up varied. The frequencies and types of complications varied by species and procedure. The postoperative complication frequencies ranged from 1% to 24% for all complications and 1% to 4% for severe complications. The results of this study describe populations of elective-surgery patients at private practices, provide data for educating clients about the risks associated with these procedures, and demonstrate how computerized records can be used to collect practice-specific medical information.     

Prevalence and duration of insensibility following electrical stunning in calves

Sixty-one calves were electrically stunned with 100-250 V currents (103-1806 mA) and the prevalence and duration of insensibility was assessed from their physical behaviour, the presence of epileptiform activity in their electrocorticograms, and the absence of visual evoked responses in their electrocorticograms. A current applied at 100 V across the head for 3 s failed to induce insensibility in all cases. Currents at 150-250 V induced insensibility in all calves and the shortest duration of insensibility was 44 s. It is recommended that a 150-200 V current would be appropriate for commercial use.     

Xylazine and a xylazine/fentanyl citrate/azaperone combination in farmed deer. I: dose rate comparison

Six 1-year-old farmed red deer were used to compare physiological and behavioural responses to a range of doses of 5% xylazine with or without the addition of 0.4 mg of fentanyl citrate and 3.2 mg of azaperone per ml. Each deer was randomly assigned to one of six treatments: xylazine alone at 0.4 and 0.6 mg/kg, the xylazinelfentanyl citrate/azaperone combination containing 0.2, 0.4 and 0.6 mg/kg of xylazine, or a sterile water control. Injections were given intramuscularly in the anterior neck, operator blind, on each of 6 sampling days between October and January, such that each deer received all treatments with 9-28 days between each treatment. Measurements included heart rate and respiration rate. A 0-3 scoring system (normal to nil response, respectively) was devised to record sedative responses (body stance, head position, degree of eye closure, palpebral reflex, resistance to movement of the head, response to noise) and analgesic responses to touch and pinching of the ear, and response to a needle prick in the gluteal region. Scores were added to produce a sedation score and analgesia score, respectively, for each treatment. Records were taken immediately prior to injection and thereafter at 5, 14, 25, 35, 60, 90, 120, 150, 180, 210, 240 and 300 minutes. All deer given each dose rate of the xylazine and the xylazine/fentanyl citrate/azaperone combination became recumbent. There was a tendency for the time to recumbency and variation of time to recumbency to be shorter at higher dose rates and with the addition of fentanyl citrate and azaperone to xylazine, particularly with xylazine at 0.4 mg/kg. These trends were not statistically significant (p>0.05). The duration of recumbency was shorter with the low dose of the xylazine/fentanyl trateiazaperone combination (0.2 mg/kg of xylazine) than for the higher doses of xylazine alone or the combination of drugs (p<0.05). There were no significant differences in heart rates or respiration rates between treatments, although all treatments significantly reduced both heart and respiration rates (p<0.01). The sedation scores showed similar peak responses and timing to peak responses (14-25 min) to both drug treatments and all dose rates, but the responses were less persistent for lower doses. The analgesia scores showed a similar pattern, with peak responses 14-35 minutes after administration and more persistence at higher dose rates of both xylazine alone and the xylazine/fentanyl citrate/azaperone combination. This study has shown that most physiological and behavioural responses to a range of doses of xylazine or the xylazine/fentanyl citrate/azaperone combination were statistically similar. However, there was a tendency for recumbency to occur more rapidly and with less variation in timing when the mid-range dose of the drug combination was used, supporting the observation by practitioners that the drug combination results in a more rapid and reliable state of recumbency at a lower dose rate of xylazine.     

The effectiveness of benzimidazole-levamisole combination drenches in the presence of resistance to both benzimidazole and levamisole anthelmintics in New Zealand sheep

Examination of 25 cases of multiple benzimidazole and levamisole resistance, identified in sheep by faecal egg count reduction testing at the Batchelar, Lincoln and Invermay Animal Health Laboratories, showed that benzimidazole-levamisole combinations provided effective control in eight (47%) of 17 cases in which they were tested. Overall, the use of combination drenches resulted in average improvements in faecal egg count reductions of 25.6% (p<0.01) and 23.2% (p<0.05), respectively, over those achieved by the use of benzimidazole or levamisole drenches alone. The results suggest that instances of multiple resistance in which combination drenches might be effective are unlikely to be predictable either by identification of the parasites involved, or from the levels of benzimidazole or levamisole resistance present.     

Book reviews

Amino Acids in Farm Animal Nutrition. Edited by J. P. F. D'Mello. 1994. 417 pp. £55.00 Wallingford, Oxon, CAB International. ISBN 0 85198 8814

Avian Hematology and Cytology. Terry W. Campbell. 1995. 104 pp. Illustrated. £48.00. Ames, Iowa State University Press. ISBN 0 8138 2970 4.     

The diagnosis of Neospora abortions in cattle

An indirect immunofluorescent antibody test (IFAT) and an enzyme-linked immunosorbent assay (ELISA) for specific anti-Neospora antibodies in bovine sera and foetal fluids were compared with histological examination results on aborted foetal material. The agreement between serological and histological examination results was poor, while the two serological tests showed a high degree of agreement. Serological testing of diagnostic serum samples and foetal fluids suggests that the prevalence of anti-Neospora antibodies in cattle which recently aborted is around 40%, in line with previous estimates of the number of abortions in dairy cattle caused by Neospora sp. A sero-epidemiological approach to the diagnosis of Neospora abortions in cattle may be suggested from these data.