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Biomedical subjects

K G Thompson

Publications and source records attributed to K G Thompson.

At least 73 records · Page 4Linked to original sources
PubMed1989

An osteodystrophy apparently caused by vitamin D deficiency in growing pigs.

An osteodystrophy with features of both rickets and fibrous osteodystrophy was diagnosed in growing pigs housed indoors and fed on a diet deficient in vitamin D. Affected pigs were severely lame and preferred to remain recumbent. At necropsy, the long bones had reduced breaking strength and in one five-month-old pig the articular surfaces of both proximal humeri were indented due to collapse of subchondral bone. Microscopic changes in the bones included prominent osteoclastic activity in the proximal metaphyses, variable myelofibrosis, trabecular microfractures, and focal thickening of the hypertrophic zone in some growth plates. Treatment consisted of an injection of Vitamin D3, addition of dicalcium phosphate to the diet for 18 days and long-term supplementation of the diet with fat-soluble vitamins. This is the first report of an osteodystrophic disease in pigs in New Zealand.

Journal Article↗
PubMed1988

Effects of glucose infusion in exercising rats.

To determine whether feedforward control of liver glycogenolysis during exercise is subject to negative feedback by elevated blood glucose, glucose was infused into exercising rats at a rate that elevated blood glucose greater than 10 mM. Liver glycogen content decreased 22.4 mg/g in saline-infused rats compared with 13.6 mg/g in glucose-infused rats during the first 40 min of treadmill running (21 m/min, 15% grade). Liver adenosine 3',5'-cyclic monophosphate (cAMP) concentration was significantly lower in the glucose-infused rats during the exercise bout. The concentration of hepatic fructose 2,6-bisphosphate remained elevated throughout the exercise bout in glucose-infused rats but decreased markedly in saline-infused rats. Plasma insulin concentration was higher and plasma glucagon concentration lower in glucose-infused rats than in saline-infused rats during exercise. Early in exercise, liver glycogenolysis proceeds in the glucose-infused rats despite the fact that glucose and insulin concentrations are markedly elevated and liver cAMP is unchanged from resting values. These observations suggest the existence of a cAMP-independent feedforward system for activation of liver glycogenolysis that can override classical negative feedback mechanisms during exercise.

Animals↗
PubMed1985

Renal osteodystrophy with facial hyperostosis and 'rubber jaw' in an adult dog.

A nine-year-old male Sheltie dog was presented with bilaterally symmetrical maxilliary swelling, loose teeth and flexible mandibles. The condition was progressive over a period of two months. Biochemical and histopathological examinations supported a diagnosis of renal osteodystrophy with facial hyperostosis and 'rubber jaw'.

Journal Article↗
PubMed1985

Effects of amount of whole cottonseed on intake, digestibility, and physiological responses of dairy cows.

In Experiment 1, 27 lactating cows were fed complete rations ad libitum of 0, 15, and 30% whole cottonseed to examine the effects on intake, digestibility, blood gases, and blood metabolites. Dry matter intake declined linearly with increased cottonseed, but because of greater energy density, calculated net energy for lactation intake was not depressed significantly. Ether extract, crude protein, and calcium digestibility increased with cottonseed in the diet. Respiration rates declined with dry matter intake and increased cottonseed feeding; some blood gases were influenced by cottonseed feeding but not in a detrimental way. No data among 13 blood metabolites indicated effects of gossypol toxicity with 30% whole cottonseed in the diet. In Experiment 2, 24 dry, nonpregnant Holstein cows were offered complete rations ad libitum of 15, 35, and 55% whole cottonseed to measure responses in intake, respiration rates, and blood metabolites. The highest cottonseed diet significantly depressed intake of both dry matter and calculated net energy for lactation. Maximum dry matter from cottonseed eaten by an individual was 8.4 kg/d (average for 1 wk). Respiration rates declined parallel to intake. No evidence for gossypol toxicity was seen among data of 11 metabolites in blood.

Animal Feed↗
PubMed1984

Osteonectin, bone proteoglycan, and phosphophoryn defects in a form of bovine osteogenesis imperfecta.

Bovine osteogenesis imperfecta is a congenital disease in Holstein cattle having several characteristics in common with human osteogenesis imperfecta syndromes. In particular, affected calves have multiple bone fractures and friable teeth. Bone collagen isolated from the affected animals (Texas variant) showed slightly decreased alpha 1(I) and alpha 2(I) chain electrophoretic mobility and increased hydroxylysine content. Overall collagen was present in the affected bones at 80-90% of normal values. However, osteonectin, a 32,000 Mr bone-specific protein found previously to promote collagen mineralization in vitro and present in abundance (approximately equal to 3% of total protein) in normal calf bone, was severely depleted (less than 2% of normal levels) in the osteogenesis imperfecta bone and dentin. The bone proteoglycan was similarly depleted. In contrast, the bone sialoprotein was not as severely affected. Further, the diseased teeth lacked (less than 10% of normal values) phosphophoryn, a dentin-specific protein normally present as 4-5% of the total calf dentin matrix. The data suggest multiple hard tissue matrix protein deletions, perhaps due to impaired cell development.

Amino Acids↗
PubMed1984

Primary hyperparathyroidism in German shepherd dogs: a disorder of probable genetic origin.

Primary hyperparathyroidism was diagnosed in two German shepherd pups from a litter of four females. Clinical signs were apparent by two weeks of age and included stunted growth, muscular weakness, and polydipsia/polyuria. Radiography revealed diffuse reduction in bone density. Both pups had marked hypercalcemia, hypophosphatemia, increased plasma immunoreactive parathyroid hormone concentrations and increased fractional clearance of inorganic phosphate in the urine. Intravenous infusion of one affected pup with calcium gluconate failed to suppress the plasma concentration of immunoreactive parathyroid hormone, suggesting autonomous secretion of parathyroid hormone. Necropsy of the other pup at eight weeks of age revealed diffuse hyperplasia of parathyroid chief cells, nodular hyperplasia of thyroid C-cells, skeletal alterations consistent with fibrous osteodystrophy, hypercalcemic nephropathy, and extensive mineralization of the lungs and gastric mucosa. The dam and sire were half sibs. One male pup from a previous litter of six had developed similar clinical signs and radiographic lesions, suggesting autosomal recessive inheritance. This is the first report of hereditary primary hyperparathyroidism in domestic animals, a disease which may be analogous to hereditary neonatal primary hyperparathyroidism in children.

Animals↗
PubMed1984

Syncytial cells in canine parathyroid glands.

Multinucleated syncytial cells consisting of clusters of closely apposed, darkly staining nuclei and densely eosinophilic cytoplasm were present in parathyroid glands from 25 of 36 dogs (69%). They were most often located either peripherally in the parathyroid gland or adjacent to blood vessels. The numbers of nuclei per syncytial cell ranged from two to greater than 30. Syncytial cells had degenerative changes as suggested by vacuolated mitochondria, dilated rough endoplasmic reticulum, irregular nuclear outlines, and condensed nuclear chromatin. These ultrastructural changes contrasted sharply with adjacent chief cells that had well-preserved organelles. The presence of desmosomes and fragments of cell membranes between nuclei suggested that syncytial cells were derived from fusion of adjacent chief cells rather than nuclear division without cytokinesis. Syncytial cells were present in normal, hyperplastic, and inactive parathyroid glands from dogs. There were no significant correlations between the presence of multinucleated cells and age of dog, parathyroid histology, and changes in the concentrations of serum calcium, phosphorus, creatinine, or plasma parathyroid hormone. Syncytial cells occurred frequently in canine parathyroid glands regardless of the state of activity of the gland or the concentration of plasma parathyroid hormone or serum calcium.

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↗
PubMed1981

Alimentary tract manifestations of bovine adenovirus infections.

Two calves and a feedlot steer with systemic bovine adenovirus infection had hemorrhagic and necrotizing lesions confined to the digestive tract. In one calf there was severe, multifocal, necrotizing, hemorrhagic rumenitis, omasitis, abomasitis, enteritis and colitis. Small intestinal lesions were predominantly in Peyer's patches. Multifocal necrotizing abomasitis was the principal change in the other calf. Large amphophilic intranuclear inclusions typical of bovine adenovirus were common in swollen vascular endothelial cells. Bovine adenovirus was isolated from the former calf. The steer had diffuse hemorrhagic enterocolitis and large numbers of BAV inclusions in vascular endothelial cells of the intestinal lamina propria. Serum-neutralization tests to bovine adenovirus type 3 on acute and convalescent samples from six clinically affected in-contact animals revealed fourfold elevations in two.

Adenoviridae Infections↗
PubMed1981

Effect of Haemophilus somnus on bovine endothelial cell in organ culture.

The effect of 2 strains of Haemophilus somnus on bovine endothelial cells in cultured arterial segments was investigated and compared with the effects of Escherichia coli and Salmonella typhimurium. In cultures inoculated with either strain of H somnus, there was widespread contraction and desquamation of endothelial cells, exposing large areas of subendothelial collagen. Many bacteria were adherent to endothelial cells and some were in phagosomes within cells. Endothelial changes were milder in arterial cultures inoculated with E coli or S typhimurium than in those inoculated with either strain of H somnus. Adhesion of H somnus to vascular endothelial cells followed by exposure of subendothelial collagen may initiate the thrombosis, vasculitis, and ischemic necrosis characteristic of infectious thromboembolic meningoencephalitis in cattle. Arterial cultures might be useful in assaying the virulences of different strains of H somnus, and could be used to investigate the mechanism of their action on endothelial cells.

Animals↗
PubMed1980

Glutathione peroxidase activity in bovine serum and erythrocytes in relation to selenium concentrations of blood, serum and liver.

The concentration of selenium (Se) in liver, serum and whole blood, and the activity of glutathione peroxidase (GSH-px) in serum and erythrocytes were monitored for seven months after the administration of Se to Se-deficient calves. There was a rapid increase in Se concentration in liver and serum, followed by an exponential decline with half-lives of 22.1 +/- 0.2 days and 28.3 +/- 2.0 days respectively. Whole blood Se concentration also increased rapidly but declined more slowly than liver or serum Se concentraations. The rise in Se concentration and GSH-px activity in erythrocytes was delayed and both levels remained elevated several months after liver and serum Se concentrations had become marginal or deficient. GSH-px activity in serum increased more rapidly after dosing and declined more rapidly than GSH-px activity in erythrocytes. The results suggest that liver and serum Se concentration and serum GSH-px activity respond to changes in dietary Se intake more rapidly than either whole blood Se or erythrocyte GSH-px activity. Two-monthly administrations of Se, at the current recommended therapeutic dose (0.1 mg Se/kg as sodium selenate) appears to be necessary to maintain adequate Se levels in calves on Se-deficient pasture.

Animals↗
PubMed1978

The pathology of bovine mannosidosis.

Mannosidosis of Angus calves is an inherited lethal disease associated with a deficiency of the lysosomal enzyme alpha=mannosidase. It is characterised by vacuolation of neurons, macrophages, fixed reticuloendothelial cells, exocrine epithelial cells and to a lesser extent a wide variety of other cells. Vacuoles are shown to be membrane-bound vesicles and are considered to be secondary lysosomes in which are stored mannose-containing oligosaccharides that result from incomplete degradation of glycoproteins. Such glycoproteins may enter the lysomal system by heterophagy, autophagy or crinophagy. The presence in the pancreas of zymogen granules in storage vesicles indicates that incomplete degradation of secretory granules might help explain the widespread vacuolation of other exocrine cells. It is suggested that such granules may enter the lysosomal system by crinophagy.

Animals↗
PubMed1977

Mannosidosis--pathogenesis of lesions in exocrine cells.

The finding of zymogen granules within lysosomal storage vesicles in pancreatic exocrine tissue in bovine mannosidosis may explain the widespread vacuolation of exocrine cells in this disease. It is uncertain if they enter the lysosomal system by the process of crinophagy but if so it would indicate that this regulatory mechanism could operate in normal exocrine tissue as well.

Animals↗