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Goodwin W Keates H Pasloske K Pearson M Sauer B Ranasinghe MG 《Veterinary anaesthesia and analgesia》2012,39(5):503-510
ObjectiveTo determine the pharmacokinetics and pharmacodynamics of the neurosteroid anaesthetic, alfaxalone, in neonatal foals after a single intravenous (IV) injection of alfaxalone following premedication with butorphanol tartrate.Study designProspective experimental study.AnimalsFive clinically healthy Australian Stock Horse foals of mean ± SD age of 12 ± 3 days and weighing 67.3 ± 12.4 kg.MethodsFoals were premedicated with butorphanol (0.05 mg kg?1 IV) and anaesthesia was induced 10 minutes later by IV injection with alfaxalone 3 mg kg?1. Cardiorespiratory variables (pulse rate, respiratory rate, direct arterial blood pressure, arterial blood gases) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and alfaxalone plasma concentrations were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis.ResultsThe harmonic, mean ± SD plasma elimination half life (t½) for alfaxalone was 22.8 ± 5.2 minutes. The observed mean plasma clearance (Clp) and volume of distribution (Vd) were 19.9 ± 5.9 mL minute kg?1 and 0.6 ± 0.2 L kg?1, respectively. Overall, the quality of the anaesthetic inductions and recoveries was good and most monitored physiological variables were clinically acceptable in all foals, although some foals became hypoxaemic for a short period following recumbency. The mean durations of anaesthesia from induction to first movement and from induction to standing were 18.7 ± 7 and 37.2 ± 4.7 minutes, respectively.ConclusionsThe anaesthetic protocol used provided a predictable and consistent plane of anaesthesia in the five foals studied, with minimal cardiovascular depression. In foals, as in the adult horse, alfaxalone has a short elimination half life.Clinical relevanceAlfaxalone appears to be an adequate anaesthetic induction agent in foals and the pharmacokinetics suggest that, with continuous infusion, it might be suitable to provide more prolonged anaesthesia. Oxygen supplementation is recommended. 相似文献
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Three cDNA clones for cytochrome P450s, CYP6B2, CYP6B6 and CYP6B7 which have 84–87% protein sequence identity have been isolated previously from Helicoverpa armigera, and the CYP6B7 mRNA was found to be over-expressed in a pyrethroid-resistant field population. Subsequent analysis has shown that over-expression is observed in a majority of individuals in all populations tested. Single-pair crosses between resistant and sensitive individuals indicated that the pyrethroid resistance co-segregated with the over-expression of this mRNA. Southern analysis indicated that the over-expression, which was confined to midgut only in many insects, was not related to gene amplification. These observations add weight to the conclusion that CYP6B7 is the cytochrome P450 form involved in pyrethroid resistance, and that over-expression of cytochrome P450 CYP6B7 is a common cause of pyrethroid resistance in H. armigera. The results suggest that specific probes for CYP6B7 protein or mRNA could provide the basis for the development of tools for monitoring pyrethroid resistance due to mixed function oxidase activity in field populations of this insect. © 1998 Society of Chemical Industry 相似文献
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Nguyen TC Nakao T Gautam G Su LT Ranasinghe RM Yusuf M 《Acta veterinaria Hungarica》2011,59(3):349-362
The main objective of the study was to describe the relationship of high somatic cell count (SCC) with the incidence of abnormal postpartum resumption of ovarian cyclicity and reproductive performance in dairy cows. The factors influencing SCC were also investigated. Four hundred and forty-seven cows from six dairy herds in Japan were monitored for SCC and postpartum resumption of ovarian cyclicity. Cows with high SCC (200,000 to 500,000) had a higher incidence of prolonged luteal phase (P < 0.01) than cows with an SCC of 50,000 to 100,000. The high SCC cows (> 500,000) also showed a higher incidence of delayed first ovulation post partum than cows with an SCC ≤500,000 (P < 0.05) during the first month post partum. Cows with an SCC of 200,000 to 500,000 showed lower conception and pregnancy rates, and more days from calving to conception than cows with an SCC of less than 200,000 (P < 0.05). Cows in parity 5 or more had a higher incidence of high SCC than cows in the first and second parities (P < 0.05). It is concluded that cows with a high SCC have a higher incidence of abnormal postpartum resumption of ovarian cyclicity, leading to reduced reproductive performance. 相似文献
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Goodwin WA Keates HL Pasloske K Pearson M Sauer B Ranasinghe MG 《Veterinary anaesthesia and analgesia》2011,38(5):431-438
ObjectiveTo determine the pharmacokinetics and pharmacodynamics of the neurosteroidal anaesthetic, alfaxalone, in horses after a single intravenous (IV) injection of alfaxalone, following premedication with acepromazine, xylazine and guaiphenesin.Study designProspective experimental study.AnimalsTen (five male and five female), adult, healthy, Standardbred horses.MethodsHorses were premedicated with acepromazine (0.03 mg kg?1 IV). Twenty minutes later they received xylazine (1 mg kg?1 IV), then after 5 minutes, guaiphenesin (35 mg kg?1 IV) followed immediately by IV induction of anaesthesia with alfaxalone (1 mg kg?1). Cardiorespiratory variables (pulse rate, respiratory rate, pulse oximetry) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and plasma concentrations of alfaxalone were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis. The quality of anaesthetic induction and recovery was scored on a scale of 1–5 (1 very poor, 5 excellent).ResultsThe median (range) induction and recovery scores were 4 (3–5) (good: horse slowly and moderately gently attained recumbency with minimal or no rigidity or paddling) and 4 (1–5) (good: horse stood on first attempt with some knuckling and ataxia) respectively. The monitored cardiopulmonary variables were within the range expected for clinical equine anaesthesia. The mean ± SD durations of anaesthesia from induction to sternal recumbency and from induction to standing were 42.7 ± 8.4 and 47 ± 9.6 minutes, respectively. The mean ± SD plasma elimination half life (t1/2), plasma clearance (Clp) and volume of distribution (Vd) for alfaxalone were 33.4 minutes, 37.1 ± 11.1 mL minute?1 kg?1 and 1.6 ± 0.4 L kg?1, respectively.Conclusions and clinical relevanceAlfaxalone, in a 2-hydroxypropyl-beta-cyclodextrin formulation, provides anaesthesia with a short duration of recumbency that is characterised by a smooth induction and satisfactory recovery in the horse. As in other species, alfaxalone is rapidly cleared from the plasma in the horse. 相似文献
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Oestrus detection error and conception rates after AI based only on secondary oestrus signs were evaluated in a high yielding, 24-h tie-stalled dairy herd with low fertility, using milk progesterone profiles. Oestrus detection was based on the secondary oestrus signs such as restlessness, swelling, congestion of vulva and clear mucus discharge. Sixty eight AI conducted after observing the secondary oestrus signs in 44 animals were included in the study. Of the 68 AI, 53 (77.9%) were conducted in the follicular phase, and 13 (19.1%) and 2 (2.9%) were carried out in the luteal phase and during pregnancy, respectively. The overall error in oestrus detection based on milk progesterone profiles was 22.1%. The oestrus detection error did not differ significantly among different secondary oestrus signs. None of the AI conducted in the luteal phase resulted in conception, whereas 20.8% of AI conducted in the follicular phase resulted in conception. No significant difference in the conception rates among the groups of cows with different secondary oestrus signs was shown. The high incidence of oestrus detection error in this study might have been caused by the detection of cows in oestrus based only on secondary oestrus signs due to the confinement of animals. In conclusion, there was a high incidence of heat detection error in the 24-h tie-stalled dairy herd and oestrus detection based only on secondary oestrus signs resulted in low conception rate. 相似文献