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1.
In 10 cats, under acute experimental conditions, the effects of distension of the oesophagus on diaphragmatic activity were studied. Bipolar recording electrodes were implanted in the diaphragmatic dome muscular fibres and crura muscular fibres. Electrodes similar to those in the diaphragm were inserted in the oesophageal muscular wall above the hiatus and in the rectus abdominis muscle. Changes in the intrathoracic pressure and blood pressure were recorded by catheters placed in the pleural cavity and carotid artery respectively. Distension of the lower part of the thoracic oesophagus (at the level between the heart and the hiatus, 5 to 7 cm from the hiatus) by inflating a balloon with 10 to 15 ml of air produced a partial or total inhibition of the inspiratory electrical activity of the inner hiatal muscular fibres, while the inspiratory electrical activity of the dome muscular fibres was generally unchanged. This inhibition was increasingly pronounced as the distension volume increased and as the balloon was positioned nearer to the hiatus. During the distension period, only electrocardiographic potentials were recorded on the oesophageal muscular wall and rectus abdominis muscle traces and no significant changes were observed from intrathoracic pressure or blood pressure channels. Distension by means of a balloon either inflated with up to 5 ml of air when placed 5 to 7 cm cranial to the hiatus or inflated with 15 ml of air when localised in the cervical oesophagus and intrahiatally produced no effect. All areas of the diaphragm were silent during expiration. 相似文献
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D. L. MOKMA J. K. SYERS M. L. JACKSON R. N. CLAYTON R. W. REX 《European Journal of Soil Science》1972,23(2):147-162
The particle-size distribution of the whole sample and the content, particle-size distribution, and oxygen-isotope abundance (δ18O) in quartz were employed to determine the extent to which aeolian materials such as aerosolic dust (10 to I /μm) from Australia, loess (50 to 10μm) in New Zealand, and flöttsand (250 to 20 μm) in Australia have been accreted into soils and sediments in the South Pacific area. Although aeolian material from both local and more distant sources has been deposited on the Franz Josef, Fox, and Tasman glaciers, the extent to which aeolian materials have been added to soils in South Westland, New Zealand, could not be determined because the oxygen-isotope abundance (12.9 to 13.5 0/00 in quartz from the soils was similar to that (13.1 to 13.9 0/00) in quartz from the dust samples. The quartz from loess added to two basaltic soils in North Auckland, New Zealand, had an oxygen-isotope abundance (12.9 to 13.9 0/00) slightly lower than that (15.0 to 15.4 0/00) in quartz from a greywacke-derived soil and the underlying rock also in North Auckland. The oxygen-isotope abundance (13.6 to 15.4 0/00) in quartz from a chronosequence of soils developed in basalt in Victoria, Australia, indicates that the quartz did not originate from the parent basalt, but probably was transported by aeolian processes from stranded beach ridges and dunes and added to the soils in the form of flöttsand, an aeolian material coarser than loess and finer than dune sand. Most particles of the pelagic sediments fell within the aerosolic dust size range. The oxygen-isotope abundance (12.1 to 15.1 0/00) in quartz isolated from several pelagic sediments between latitudes 35 and 45° S. was similar to that (12.9 to 15.4 0/00) in quartz from New Zealand and Australian soils located between these latitudes. An aeolian source of quartz explains the above relationship and also the decreasing delta values of quartz from sediments and soils with increasing latitude in the South Pacific area. Oxygen-isotope abundance in quartz refutes a volcanic origin of quartz in pelagic sediments but supports the deduction of Griffin et al. (1968) from mineralogical analyses that the quartz and associated minerals were transported from lands to seas. 相似文献
3.
MAE REX 《Australian veterinary journal》1993,70(10):369-372
SUMMARY Veterinary educators all over the world are concerned about the explosion in knowledge and about the way veterinary science is taught at present. How can we produce veterinarians who will provide the sort of care that will be expected in the year 2000 and beyond? In the recent past many schools have increased the information presented in their courses without removing any material. Student stress has increased, and undergraduates do not retain what they are taught. The type of assessment that is currently used often requires regurgitation of ‘facts’ rather than the solution of problems. This paper considers some of the issues that are pertinent to the future of veterinary education and suggests ways in which the situation may be improved. There is a need for increased activity by the Australian Veterinary Association to convince government that present funding is inadequate and that increased funding is urgently needed if we are to produce veterinarians of the quality the country will need in the next century. 相似文献
4.
IRINA POLLARD SUSAN WILLIAMSON JEFF DOWNING REX SCARAMUZZI† 《Journal of veterinary pharmacology and therapeutics》1996,19(2):113-117
The disposition kinetics of caffeine and its metabolites theophylline, theobro-mine and paraxanthine in the oestrogen-implanted ovariectomized ewe following single intravenous doses of 5, 10, 15 or 20 mg/kg caffeine are described in this paper. Blood was collected at 5, 30 and 60 min, and at 3, 6, 8, 12, 24, 48, 72, 96, 120, 144, 192 and 240 h after dosing. Caffeine concentrations peaked within 30 min of administration but remained in a plateau phase for 3-6 h before declining over a prolonged period of time. For caffeine the mean elimination half-life was calculated to be 47 h. Detectable caffeine concentrations remained for 10 days after administration in all groups. The area under the plasma concentration-time curve ( AUC ) values were used to compare tissue caffeine exposure and were, approximately, linearly related to dose. Metabolite concentrations were maintained at peak and near peak concentrations for 6-24 h after caffeine administration followed by prolonged elimination. Because of significant species differences in drug elimination rates, it is concluded that the ewe is not a suitable animal model in the clinical context. However, the sheep may well provide insights into caffeine's mechanism of action of relevance to veterinary drug research. 相似文献
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Diffusion tensor imaging (DTI) is a specialized magnetic resonance sequence to determine the direction of water molecule motion. Our hypothesis was that information derived from DTI will be significantly different in dogs with a spinal cord lesion compared with a normal dog. Eleven normal dogs and six dogs with a spinal cord lesions were imaged. DTI was performed along with standard T1‐ and T2‐weighted sequences in transverse and sagittal planes. Fractional anisotrophy and apparent diffusion coefficient (ADC) were obtained using regions of interests centered on the cranial aspect, middle cranial, middle caudal, and caudal aspects of the spinal cord. In normal dogs, the DTI sequence was characterized by normal fiber tracking with no statistical difference between the four sections of spinal cord (P>0.05). In the dogs with a spinal cord lesion, there was a significant difference in fractional anisotropy between the two groups (P=0.0003) and the ADC analysis statistical significance (P=0.048) at the caudal most site. Based on these findings, DTI is a potentially useful method to evaluate the spinal cord in dogs. 相似文献
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Abstract. The Chilean oyster, Ostrea chilensis Philippi, shows high phenotypic variability for growth rate within populations. In order to determine if the serial correlation of growth rate in oysters is positive, the correlation between shell height and live weight at different stages of the life cycle in a cohort of the Chilean oyster was estimated. Four size groups of individually tagged oysters selected on the basis of their shell heights were examined. The relationships for juvenile and adult oysters were found to be positively correlated throughout the study period. The correlation coefficients ranged from r = 0.28 to r = 0.83. For shell height the coefficient of determination for market size oysters was higher in 2-year-old (r2 =0.88) than in 1-year-old oysters (r2 =0.09). Shell height and live weight were more highly correlated at later stages of the life cycle. The results indicate that 2-year-old oysters have a size that is indicative of performance to market size and hence is an appropriate age to select the parents to be used in breeding programmes to improve the growth rate in O. chilensis . A high mortality was detected after the natural spawning period. A physiological stress hypothesis is proposed to explain the high summer mortality in O. chilensis in the Quempillen estuary, southern Chile. 相似文献
9.
选取3 240只AA肉仔鸡随机分为6组,每组6个重复,每个重复90只鸡。对照组饲喂基础日粮,试验组分别在饲养的前、中、后期添加10%、20%、30%的豌豆来研究在肉鸡日粮中添加不同水平的豌豆对肉鸡生产性能的影响。结果表明:在试验前期,不管日粮中添加10%、20%、30%的豌豆,均可极显著(P<0.01)降低肉鸡的日采食量,但从肉鸡全程的饲养数据看,即使前、中、后期日粮中的豌豆添加比例均达到30%,对肉鸡全程的生产性能(成活率、末重和肥育指数)和全净膛率没有显著影响(P>0.05)。 相似文献
10.
The effects of allopurinol on the ultrastructure of ischaemic and reperfused large intestine of sheep 总被引：1，自引：0，他引：1
M AHMADINEJAD MAE REX RH SUTTON CC POLLITT B CRIBB 《Australian veterinary journal》1996,74(2):135-139
Objective To test the possible inhibitory effect of allopurinol on reperfusion injury, caused by oxygen-derived free radicals, of sheep large intestine.
Design An ultrastructural study on caecal tissues from control and treated groups.
Fifty sheep in four ischaemic and reperfused (treatment) groups and one control group. Three of the treatment groups were subdivided for half to be injected with allopurinol and the other half with its solvent, potassium hydroxide (KOH).
Procedure Ischaemia of the caecum was induced in the four treatment groups for 60 minutes by clamping the apex. Allopurinol and its KOH solvent were injected intravenously in three treatment groups prior to ischaemia. Samples were collected before and 1 hour after induction of ischaemia and 1 min, 1 h and 8 h after reperfusion. Tissues were processed and examined with an electron microscope.
Results Untreated and solvent injected sheep showed minor ultrastructural changes following ischaemia. With reperfusion, there was severe mitochondrial, goblet cell and basement membrane damage. Tissues from allopurinoltreated sheep were preserved and appeared similar to tissues from the control group.
Pre-treatment with allopurinol prevented damage to tissues whereas untreated or allopurinol solventtreated showed severe damage following reperfusion. It is believed that allopurinol, an analogue of hypoxanthine and xanthine, prevents reperfusion injury by competitively binding with xanthine oxidase. This reduces or inhibits the xanthine oxidase mediated conversion of hypoxanthine to xanthine thereby preventing the formation of oxygen-derived free radicals. 相似文献
Design An ultrastructural study on caecal tissues from control and treated groups.
Animals
Fifty sheep in four ischaemic and reperfused (treatment) groups and one control group. Three of the treatment groups were subdivided for half to be injected with allopurinol and the other half with its solvent, potassium hydroxide (KOH).
Procedure Ischaemia of the caecum was induced in the four treatment groups for 60 minutes by clamping the apex. Allopurinol and its KOH solvent were injected intravenously in three treatment groups prior to ischaemia. Samples were collected before and 1 hour after induction of ischaemia and 1 min, 1 h and 8 h after reperfusion. Tissues were processed and examined with an electron microscope.
Results Untreated and solvent injected sheep showed minor ultrastructural changes following ischaemia. With reperfusion, there was severe mitochondrial, goblet cell and basement membrane damage. Tissues from allopurinoltreated sheep were preserved and appeared similar to tissues from the control group.
Conclusion:
Pre-treatment with allopurinol prevented damage to tissues whereas untreated or allopurinol solventtreated showed severe damage following reperfusion. It is believed that allopurinol, an analogue of hypoxanthine and xanthine, prevents reperfusion injury by competitively binding with xanthine oxidase. This reduces or inhibits the xanthine oxidase mediated conversion of hypoxanthine to xanthine thereby preventing the formation of oxygen-derived free radicals. 相似文献