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Biomedical subjects

J B Smyth

Publications and source records attributed to J B Smyth.

10 recordsLinked to original sources
PubMed1997

Concentrations of isometamidium chloride (Samorin) in sera of Zebu cattle which showed evidence of hepatotoxicity following frequent trypanocidal treatments.

The concentrations of isometamidium circulating in poorly nourished Zebu cattle which showed morbidity, mortality, and biochemical and histopathological evidence of hepatotoxicity, following frequent treatments with isometamidium chloride and diminazene aceturate were investigated using the isometamidium-ELISA. As few as two isometamidium treatments one month apart were associated with significant weight loss, and cattle treated with diminazene aceturate after three or four isometamidium treatments suffered a 50% mortality. Although there were no obvious, marked elevations in isometamidium concentration which might have allowed the use of the ELISA as a predictor of a potential toxicity problem, concentrations did increase significantly with the number of monthly treatments administered, suggesting drug accumulation, and the increases were significantly higher in cattle to which diminazene had also been administered. In cattle treated with both trypanocides, weight loss and serum glutamate dehydrogenase levels were correlated with isometamidium concentrations. These observations, together with the histopathological findings, support the hypothesis that the morbidity and mortality observed were related to the repeated treatment with isometamidium in conjunction with diminazene aceturate, and that the pathogenesis involved a component of hepatic damage. It is therefore recommended that cattle, particularly those under nutritional stress, are not subjected to repeated treatments with isometamidium at intervals as short as one month, and particularly not with concurrent administration of diminazene.

Animals↗
PubMed1995

Cholecystokinin-8 induces edematous pancreatitis in dogs associated with short burst of trypsinogen activation.

To study the early pathogenesis of acute edematous pancreatitis in dogs, we examined the relationship of pancreatic hyperstimulation with cholecystokinin-8 (10 micrograms/kg/hr intravenously for 6 hr) to alterations in circulating pancreatic enzymes and pancreatic morphology with special reference to trypsinogen activation. Cholecystokinin-8 infusion was associated with increases in plasma amylase, lipase, trypsin-like immunoreactivity, and plasma and urine trypsinogen activation peptide. Pancreatic parenchymal swelling and interlobular and subcapsular fluid accumulations were detected ultrasonographically within 2 hr of cholecystokinin-8. Circulating trypsin-like immunoreactivity and trypsinogen activation peptide in urine reached a peak at 2 and 4 hr, respectively, then declined despite progressive increases in circulating amylase and lipase and intrapancreatic fluid. No significant changes were observed in dogs receiving a saline infusion. This study illustrates that cholecystokinin-8 induces edematous pancreatitis in dogs that is associated with a short-lived burst of trypsinogen activation.

Acute Disease↗
PubMed1990

Experimental acute selenium intoxication in lambs.

The toxic effects of 5 mg per kg body weight of selenium given as sodium selenite orally or parenterally to growing lambs were examined. There was considerable individual variation in both susceptibility to intoxication and the degree of pathological change displayed. The results affirm the previously reported deleterious effects on the cardiovascular, respiratory and urinary systems and highlight damage to secondary lymphoid tissue in various organs. The use of a histochemical method for detecting selenium bonds demonstrated correlation between the density of reaction-product and histopathological changes within tissues, and showed the distribution of selenium in other tissues in which the gross and histopathological findings were non-specific or minimal.

Administration, Oral↗
PubMed1990

Effects of concurrent oral administration of monensin on the toxicity of increasing doses of selenium in lambs.

The effects of concurrent administration of monensin sodium on the toxicity of progressively increasing oral doses of selenium (0.2 to 2.4 mg per kg body weight), given as sodium selenite twice weekly, have been examined in growing lambs. To link the chemically determined selenium concentration in tissues with observable pathological changes, the histochemical method of Danscher, which visualizes selenium bonds within tissues, was utilized. Findings included damage to conduction and contractile myofibres in the heart, segmental sarcoplasmal necrosis with lysis and atrophic change in skeletal musculature and selective accumulation of Danscher reaction-product in damaged areas of the liver, kidney and secondary lymphoid tissue. Concurrent administration of monensin sodium at a constant safe dosage enhanced the toxicity of selenium as demonstrated by increased severity of the signs of intoxication, fatalities, tissue selenium concentrations and intensified gross, histopathological and histochemical changes.

Administration, Oral↗
PubMed1987

A myopathy associated with muscle hypertonicity in the Cavalier King Charles Spaniel.

Clinical signs of electrically silent muscle hypertonicity are described in five Cavalier King Charles dogs. Biopsies of the biceps femoris and triceps muscles, when examined with the electron microscope, revealed evidence of sarcotubular and mitochondrial abnormalities. These included enlargement of the sarcoplasmic reticulum, hydropic degeneration of mitochondria, tubular proliferations in the vicinity of the triads and vacuolar invagination of mitochondria. The exact nature of these findings is not clear and it is suggested that utilization of tracer techniques would help to explain them.

Animals↗
PubMed1984

Histochemical studies on the zona reticularis of stress-susceptible pigs.

During an investigation into the role of the adrenal gland in stress susceptibility of pigs, the large lipid masses in the inner zona reticularis were seen to be particularly related to sex differences, although stress-susceptible castrates had significantly more lipid in this zone than had stress-resistant castrates. Significant histochemical differences were also found in the activity of glucose-6-phosphate dehydrogenase and succinic dehydrogenase between the sexes and between castrates of differing susceptibility to stress. The differences in histochemical activity suggest a different origin for some of the adrenocortical cells in the inner zona reticularis.

Adrenal Cortex↗