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Biomedical subjects

R J Sutherland

Publications and source records attributed to R J Sutherland.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effects of neonatal forebrain noradrenaline depletion on recovery from brain damage: performance on a spatial navigation task as a function of age of surgery and postsurgical housing.

The experiments examined the contributions of forebrain noradrenaline and environmental enrichment to recovery of place navigation ability in rats after hemidecortication in infancy or adulthood. Noradrenaline depletion did not affect recovery from neonatal hemidecortication, although the early hemidecortications did allow sparing of function relative to adult operates. Noradrenaline depletion also failed to attenuate the positive effects of enriched housing on otherwise normal rats. Noradrenaline depletion did retard recovery of adult hemidecorticate rats housed in standard laboratory cages, but it did not retard recovery of adult hemidecorticate rats housed in enriched environments. The results suggest that noradrenaline is importantly involved in enhancing recovery from brain damage when other sources of compensation (e.g., neonatal injury, enriched environment) are absent.

Animals↗
PubMed1986

A comparative study of diagnostic tests for the assessment of herd magnesium status in cattle.

In nine of ten pre-calving dairy herds we found that herd magnesium (Mg) status could be determined with 95% confidence by measurements of serum Mg (S-Mg), urinary Mg fractional clearance ratio (FCR) or creatinine corrected urinary Mg concentration (CUM) from 10 representative cows. Our findings support clinical impressions that FCR and CUM are more sensitive than S-Mg as predictors of a positive production response to Mg supplementation of dairy cows. The available clinical data is not adequately controlled and there is a need for controlled production-response trials to refine interpretation and to confirm the predictive value of these tests. Pending such trials we suggest that mean FCR >10% or CUM >1.0 mmol/l indicate that a positive response is likely. In seven lactating herds the act of milking was not associated with depression of S-Mg and we conclude that sampling cows immediately after milking Gould not result in spurious elevations of FCR. FCR and CUM show close correlation with each other but not with S-Mg.

Journal Article↗
PubMed1985

Clinical pathology - the problem oriented approach to laboratory support in clinical veterinary medicine.

An adequate diagnosis allows the development of specific treatment and preventive strategies for problems encountered in clinical practice. Such a diagnosis must sustain reasonable scientific challenge and needs to be founded on objective clinical and/or laboratory findings. The problem-oriented system optimises the chance of achieving this while making it possible to improve performance through self-assessment and through the development of a standard, rational, and comprehensive approach to the diagnosis of clinical problems. This system enhances the scientific aspects of veterinary diagnosis and is an effective means of incorporating laboratory support into clinical veterinary medicine.

Journal Article↗
PubMed1984

Catastrophic death losses in a dairy herd attributed to type D botulism.

Clostridium botulinum type D intoxication was diagnosed as the cause of death of 42 of 67 lactating cows in a southeast Texas dairy herd over an 11-day period. By necessity, the diagnosis was based on clinicopathologic findings, as the toxin could not, by standard laboratory tests, be demonstrated in affected cattle. The predominant clinical findings were hindlimb weakness/ataxia rapidly progressing to persistent recumbency. Affected cattle were alert until just before death, which occurred without notable agonal movements or respirations after 6 to 72 hours' recumbency. Abnormal laboratory findings included neutrophilic leukocytosis (all affected cattle), proteinuria (most affected cattle), slight elevations of serum aspartate transaminase and low serum inorganic phosphorus (some affected cattle), and patchy areas of hyperemia/congestion of the mucosa in the small intestine (postmortem examination of 3 affected cattle). This report confirms the findings of others with regard to the difficulty of demonstrating the causative toxin in C botulinum type D-intoxicated cattle and presents available information on the clinicopathologic features of this intoxication that may aid in the differentiation of this condition from other causes of down cows.

Animals↗
PubMed1984

Evidence for anatomical but not functional asymmetry in the hemidecorticate rat.

Rats with unilateral ablation of the left or right cerebral neocortex or left or right hippocampus were studied in a battery of tests of spatial orientation, motor coordination, and social behavior, including Morris water task, radial arm maze, feeding, narrow beam traversing, puzzle latches, hoarding, grooming, nest building, running wheel activity, male--male interaction, and shock-induced aggression. Comparison of the brains of operated and control rats confirmed previous suggestions that the right hemisphere of the rat is bigger and may have different connections than the left hemisphere. Despite the morphological asymmetries, comparison of the behavior of rats with right hemidecortication with that of rats with left hemidecortication, and of rats with right and of those with left hippocampal lesions, failed to show a single instance of functional asymmetry in the rat brain. These behavioral results stand in marked contrast to previous reports of functional asymmetry in the control of activity, orientation, and rotation.

Afferent Pathways↗
PubMed1984

Giardiasis in intensively reared Saanen kids.

Outbreaks of diarrhoea in two groups of Saanen.kids aged 4 to 6 weeks were ascribed to giardiasis, although Cryptosporidia were also present. In all, 45 out of 65 kids were affected, two animals died, and the remainder eventually recovered. Aspects of the epidemiology and diagnosis of giardiasis are discussed. Air dried smears prepared from small intenstinal mucosa, intestinal contents, or freshly-voided faeces proved to be suitable for making a diagnosis, and are the recommended sample when laboratory examination will be delayed beyond a few hours.

Journal Article↗
PubMed1983

Abnormalities in cortical and subcortical morphology after neonatal neocortical lesions in rats.

The brain weight, cortical thickness, cross-sectional areas of subcortical structures, and various retrograde changes were compared in rats with neonatal or adult ablation of all or part of the neocortex. Neonatal lesions produced a widespread reduction in brain size accompanied by a variety of major structural changes including modification of the thickness of the residual cortex, necrosis and calcification of subcortical structures, and gross distortion of the structure of the hippocampus. The modification of the cortical thickness, but not the other changes, depended on the site and extent of cortical removal: neonatal frontal cortex ablation reduced the thickness of the remaining neocortex, neonatal posterior cortex ablation had no significant effect upon the thickness of the remaining neocortex, and neonatal hemidecortication increased the thickness of the remaining neocortex.

Animals↗
PubMed1983

Sporidesmin toxicity in rabbits: biochemical and morphological changes.

The earliest lesion in rabbits dosed orally with 2 mg of sporidesmin per kg of body weight was necrosis of occasional hepatocytes 1 day after dosing. The most consistent lesion was a severe necrotizing cholangitis of medium and large-sized intrahepatic and extrahepatic bile ducts, first seen 2 days after dosing. Similar lesions were also present in the gall bladder of some rabbits. Expansion of portal triads with fibrous tissue and proliferating bile ductules progressed to pseudo-lobulation by 21 days. Other hepatic changes observed irregularly included large infarcts at the periphery of some lobes, and multiple small foci of coagulation necrosis in midzonal and periportal regions. Vascular necrosis and thrombosis, invariably adjacent to necrotic bile ducts, was presumably responsible for the hepatic necrosis. Serum cholesterol and total bilirubin concentrations and GGT activity reached peaks 15 days after dosing and were useful indicators of the severity of biliary lesions. Serum ID activity was the most useful indicator of hepatic necrosis following oral dosing with sporidesmin. The similarity between hepatobiliary lesions observed in sheep and rabbits with experimental sporidesmin toxicity suggests that the rabbit would be a useful model for studying methods of treatment and prevention of "facial eczema" in ruminants.

Animals↗
PubMed1983

A behavioural analysis of spatial localization following electrolytic, kainate- or colchicine-induced damage to the hippocampal formation in the rat.

This experiment examines the notion that in the rat the hippocampal formation is an essential structure in the neurological representation of spatial abilities. Spatial localization by rats with different types of hippocampal damage, including bilateral electrolytic lesions, unilateral and bilateral kainic acid-induced CA3-CA4 lesions, and unilateral and bilateral colchicine-induced dentate gyrus lesions, was compared with vehicle-injected and normal control groups in the Morris water task. The task required the rats to escape from cold water by finding a submerged and hidden platform located at a fixed place within the room. The start point was varied randomly from trial to trial and there were no local cues available to indicate the position of the hidden platform. After training, the platform was moved. Escape latencies and the initial swimming headings revealed that all lesion groups, except the unilateral CA3-damaged group, were impaired at finding the platform: the dentate-damaged rats exhibited the greatest deficit. When the platform was moved the control rats swam mainly in the part of the pool that had previously contained the platform and, on finding it in the new location, they showed a marked dishabituation of rearing. None of the bilateral lesion groups showed these effects.

Animals↗
PubMed1983

A comparison of the contributions of the frontal and parietal association cortex to spatial localization in rats.

Rats with lesions of the medial frontal, orbital frontal, or parietal cortex were compared behaviorally with rats with complete removal of the neocortex and normal control rats on three spatial tasks: Morris water task, radial arm maze, and spatial reversals in a Grice box. Decortication produced severe impairments in the acquisition of all three tasks, thus providing a measure against which to compare the severity of the impairments observed following more restricted removals. Rats with parietal cortex lesions were relatively unimpaired at any of the tasks, although they had a significant deficit on the spatial reversal task and had a short-term memory impairment on the radial arm maze. In contrast, rats with medial frontal lesions had a significant, but relatively mild, impairment on the radial arm maze and were very poor at learning the water task. Rats with orbital frontal lesions were nearly as impaired on the radial arm maze and water task as decorticate rats. The results suggest that the frontal and parietal cortex of rats play different roles in the control of spatial orientation but do not support the view that egocentric and allocentric spatial orientation are related to frontal and parietal mechanisms, respectively. In addition, the results suggest that the frontal cortex plays a larger role in the control of spatially guided behavior than has been previously recognized and that both the medial frontal and the orbital (sulcal) frontal cortex play a dissociable role in the control of spatial orientation.

Animals↗
PubMed1983

Neonatal hemidecortication or frontal cortex ablation produces similar behavioral sparing but opposite effects on morphogenesis of remaining cortex.

Rats with complete removal of the neocortex of one hemisphere (hemidecorticate) or of the cortex anterior to bregma in both hemispheres (frontal cortex) in adulthood were compared behaviorally and neuroanatomically with rats with similar removals at 7 days of age. Neonatal ablation of the frontal cortex produced partial sparing of performance on the Morris water task and reduced the thickness of the remaining neocortex. Neonatal hemidecortication produced similar sparing of function on the water task but increased the thickness of the contralateral neocortex. These results imply that behavioral sparing following neonatal cortical lesions is independent of the gross morphogenesis of the remaining neocortex.

Age Factors↗
PubMed1983

Cortical control of claw cutting in the rat.

Claw cutting emerges as a behavior between Postnatal Day 30 and 50, and by Day 100 at least 80% of rats have cut their claws. Complete frontal ablation or total decortication at any age abolished claw cutting, but complete posterior neocortex removal did not. In adult rats, motor cortex ablations or hemidecortications abolished claw cutting, whereas the same lesions given to infant rats spared claw cutting. Neonatal telencephalic noradrenaline depletion had no effect on the development or incident of claw cutting. Loss of claw cutting appears to be due to loss of efficient biting and chewing rather than to an inability to orient or to groom. The sparing after infant ablations may be due to functional reorganization of tissue within, or adjacent to, the developing motor cortex. The study demonstrates that careful examination of features of the laboratory rat's appearance can provide useful clues about its behavioral competencies. Furthermore, abnormalities such as loss of claw cutting can serve as a useful diagnostic indication of specific kinds of brain damage.

Animals↗
PubMed1982

Cortical noradrenaline depletion eliminates sparing of spatial learning after neonatal frontal cortex damage in the rat.

The possibility that cortical noradrenaline (NA) is necessary for the sparing of function that occurs after neonatal frontal cortex damage was examined. Spatial localization by rats with frontal cortex damage sustained neonatally was better than by rats with similar damage sustained as adults. The sparing was abolished in rats depleted of cortical noradrenaline by means of neonatal 6-hydroxydopamine (6-OHDA) administration. NA depletion alone did not affect spatial localization. These data are consistent with the notion that NA has some general function in maintaining some forms of plasticity in posterior cortex.

Animals↗