Development of biomarkers inAporrectodea caliginosa andLumbricus rubellus for detecting exposure to benzo[a]pyrene

Objectives and Methods. The sensitivity of two biomarkers, the neutral red retention assay (NRRA) and cytochrome P450 were evaluated in the earthwormAporrectodea caliginosa for their potential to detect exposure to benzo[a]pyrene (BaP). Cytochrome P450 was also evaluated in the earthwormLumbricus rubellus, and measured using the substrate ethoxycoumarin. Optimal assay conditions (pH, and temperature) were determined, followed by exposure of earthworms to 20 mg/kg BaP (a typical concentration at contaminated sites in New Zealand). Ethoxycoumarin-O-dealkylase (ECOD) activity was measured after 7, 14, and 21 days exposure. The NRRA was evaluated in earthworms exposed to 0.2, 20, and 100 mg BaP/kg, and biomarker responses were compared with effects on body weight. Results and Discussion Benzo[a]pyrene failed to induce ECOD activity in either earthworm species, and therefore it is not useful as a biomarker of BaP exposure and was not evaluated further. In all cases, the NRRA was significantly affected in the absence of any effects on earthworm body weight, indicating that this assay can detect exposure to BaP at a range of concentrations comparable to those found at contaminated sites. The NRRA should be linked to reproductive endpoints, then it can be used as an early warning indicator of adverse effects. Establishing biomarker stability under environmental conditions is an important step in biomarker development. Therefore, the effects of soil type (sandy soil, silt loam, and a clay soil), moisture content (15–30%), and temperature (5–20°) on the NRRA were determined. In all cases, there was no effect on the NRRA, indicating that this assay is very stable under varying environmental conditions. Conclusion and Outlook In conclusion, cytochrome P450 activity does not appear to be a useful indicator of PAH exposure in eitherA. caliginosa or L.rubellus, and due to the inherently low activity, it is not suitable as a routine biomarker for detecting environmental contamination by these compounds. In contrast, the NRRA in the earthworm A.caliginosa is a promising indicator of PAH exposure at the concentrations likely to be found in contaminated sites in New Zealand, and therefore has potential for evaluating these contaminated sites. If the NRRA can be linked to ecologically important life-cycle endpoints, such as reproduction, then it could be used as an early warning indicator of adverse effects at contaminated sites, i.e., by measuring biomarker responses in earthworms from a ‘contaminated area’ and comparing these with earthworms from a matched control area.     

Calving rates in a tropical beef herd after treatment with a synthetic progestagen, norgestomet, or a prostaglandin analogue, cloprostenol

Maiden heifers and lactating cows of known ovarian status and of several breeds were treated with a synthetic prostaglandin, cloprostenol, or a synthetic progestagen, norgestomet, at the start of an artificial insemination (AI) program. Animals in the cloprostenol treatment received 2 injections 10 days apart. Over the next 26 days those animals that showed oestrous behaviour were inseminated. Synchronisation rates and calving rates to insemination over the first 7 days were calculated. Those in the norgestomet treatment received an implant of norgestomet plus an injection of norgestomet and oestradiol valerate. The implant was removed 10 days later and the animals were given an injection of pregnant mare serum gonadotrophin (PMSG). They were inseminated at 48 h (maiden heifers) or 56 h (lactating cows) after implant removal. Calving rates to fixed-time insemination were recorded. After completion of the AI program the animals in both treatments were joined with bulls. Overall calving rates (AI plus bulls) were calculated. By day 7 of the program, 82% of the maiden heifers and 76% of the lactating cows in the cloprostenol treatment had been detected in oestrus. By day 21 the respective figures were 99% and 81% Norgestomet treatment had an immediate and a prolonged effect on ovarian activity in those females classified as having inactive ovaries at the start of the AI program. Calving rates of those females to fixed-time AI and overall were similar to those of the females with active ovaries in both treatments. Their calving rates to fixed-time insemination, and overall calving rates for the lactating females, were significantly higher than the corresponding values of their contemporaries treated with cloprostenol and inseminated on observed oestrus over 7 days. For those females classified as having active ovaries at the start of the AI program, calving rates to first insemination and overall were similar for both treatments. Overall calving rates of lactating cows of each breed were, with one exception, higher in the norgestomet treatment than in the cloprostenol treatment. Although norgestomet treatment was more expensive than cloprostenol treatment, the advantage in calf crop resulted in an overall monetary advantage to the norgestomet treatment.     

Antagonism of xylazine sedation by 4-aminopyridine and yohimbine in cattle

Twenty-four crossbred steers (4 groups of 6 steers each) were injected IM with a standard dosage range of xylazine hydrochloride (0.2 to 0.3 mg/kg of body weight). When the steers were maximally sedated, group I (control group) were given isotonic saline solution (1 ml, IV), group II were given 4-aminopyridine (4-AP, 0.3 mg/kg) IV, group III were given yohimbine hydrochloride (0.125 mg/kg) IV, and group IV were given 4-AP (0.3 mg/kg) plus yohimbine hydrochloride (0.125 mg/kg) IV. The 4-AP decreased mean standing time (MST; time until animal could stand unaided) from 94.3 minutes (control) to 13.4 minutes. Yohimbine decreased MST to 27 minutes. The combination of 4-AP + yohimbine decreased MST to 7.4 minutes. Mean total recovery time (MTRT; time from xylazine injection until normal behavior, including eating and drinking) was not significantly (P = greater than 0.05) decreased from control values by any of the antagonists tested. The combination of 4-AP + yohimbine decreased MST in animals given a 3X overdose of xylazine (0.6 mg/kg) from 124 minutes (control) to 30.3 min. The MTRT was not significantly (P greater than 0.05) decreased from control values. Two animals given a 5X overdose of xylazine (1 mg/kg) and then given 4-AP + yohimbine had a MST of 32.5 minutes and a MTRT of 3.7 hours. The combination of 4-AP + yohimbine produced marked antagonism of xylazine sedation in cattle. The combination of antagonists may prove to be useful for the arousal of animals sedated with xylazine alone or with a combination of sedatives including xylazine.     

Effect of yohimbine hydrochloride on serum prolactin concentration in the rat: possible antagonist for fescue toxicosis

Yohimbine hydrochloride is an indole alkaloid which blocks alpha 2-adrenergic and dopamine receptors and stimulates serotonergic receptors. Yohimbine was selected for testing as a possible antagonist in fescue toxicosis. Reduced body weight gains in cattle with chronic fescue toxicosis may be due to ergot alkaloids produced by fungi which infect the fescue grass. Ergot alkaloids stimulate dopamine receptors, antagonize serotonin, and lower serum prolactin concentrations. It was hypothesized that yohimbine may reverse or counteract the effects of the toxic fescue. Investigation was made of the treatment effects of multiple doses of yohimbine given in rats by intraperitoneal and oral routes. Given intraperitoneally once a day for 8 days, yohimbine hydrochloride increased serum prolactin concentrations. When given orally in feed for 7 days, the drug decreased the serum prolactin concentration. The effects of yohimbine on prolactin concentrations were dependent on the dosages and routes of administration. The inability of yohimbine, when given orally, to increase serum prolactin levels decreased its potential usefulness for prolonged treatment of fescue toxicosis.     

Controlled clinical trial of the effect of a homoeopathic nosode on the somatic cell counts in the milk of clinically normal dairy cows

Cows in a 250-cow Holstein-Friesian herd were allocated at random to be treated with either a homoeopathic nosode or a negative control, both treatments being applied by means of an aerosol spray to the vulval mucous membranes. A total of six treatments were given over a period of three days and milk samples were taken for the determination of somatic cell counts (SCC) on days -3, 3, 7, 9, 14, 21 and 28. Individuals applying the treatments or carrying out the SCC determination were unaware of which animals were receiving which treatment. Owing to the wide natural variations in SCC, the trial had only a 71 per cent possibility of detecting a 30 per cent difference in SCC between the two groups. There were no significant differences between the SCC of the two groups on any sample day, but there were significant variations between the SCC on different days (P=0.003) in both groups.     

Effect of age at presentation on outcome following arthroscopic debridement of subchondral cystic lesions of the medial femoral condyle: 85 horses (1993--2003)

REASONS FOR PERFORMING STUDY: Subchondral cystic lesions of the medial femoral condyle (SCMFC) are well documented in horses < or =3 years; arthroscopic debridement or enucleation of the cyst is currently the surgical treatment of choice. However, studies of occurence and outcome following surgery in older horses are lacking. OBJECTIVE: To identify factors important in outcome for horses with SCMFC treated by arthroscopic debridement. HYPOTHESIS: Age of horse at presentation has a significant influence on return to work following arthroscopic treatment for SCMFC. Clinical and diagnostic findings are also significant with respect to prognosis. METHODS: A retrospective review of medical records from 6 equine referral centres identified 85 horses that underwent arthroscopic debridement of SCMFC. Clinical examination, radiographic and arthroscopic findings were analysed together with follow-up data. Univariable analysis and multivariable logistic regression models were used to determine factors affecting return to soundness. Event-time analysis was performed to evaluate return to work. RESULTS: Older horses (>3 years) were less likely to return to soundness (P = 0.02) or to work (P = 0.04) than younger horses (< or = 3 years). Of 39 horses age 0-3 years, 25 (64%, 95% CI 49-79%) returned to soundness. Of 46 horses age >3 years, 16 (35%,95% CI 21-49%) returned to soundness. In addition, cartilage damage at sites other than the SCMFC negatively affected prognosis (P = 0.05). The hospital where treatment was performed had no influence on return to soundness. CONCLUSIONS: Older horses carry a worse prognosis for both return to soundness and return to work. Potential relevance: It is important for clients to be made aware of the difference in outcome between age groups.