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Biomedical subjects

A E Ferguson

Publications and source records attributed to A E Ferguson.

15 recordsLinked to original sources
PubMed1992

Biliary function studies during multiple time periods in freely moving rats. A useful system and set of marker solutes.

Biliary output of endogenous and exogenous compounds is altered by anesthesia, depletion of bile salts, and hydrostatic pressure. The described system for bile function studies minimizes these confounding factors by substantially modifying existing methods. Experiments were conducted in freely moving rats which eliminates effects of anesthesia or restraint-induced stress. Depletion of bile salts was prevented by intraduodenal infusion of taurocholate which maintains bile volume. Bile was collected in containers taped to the rat's back which minimizes hydrostatic forces induced by lengthy or elevated biliary cannulas. Animals were prepared for hepatobiliary function studies 1 week before experiments by placement and exteriorization of a jugular cannula and a bile duct to duodenal fistula. Experiments involved monitoring biliary outputs of marker solutes for various pathways of bile formation during three sequential time periods of 120 min, that is, a basal period in the morning and two experimental periods in the afternoon. We found similar patterns of biliary output in each time period for small i.v. doses of conventional exogenous markers [3H-taurocholate, phenolphthalein glucuronide, indocyanine green, and horseradish peroxidase] and for less commonly studied endogenous markers [glucose, inorganic phosphate (Pi), total protein, and leucine aminopeptidase]. This temporal stability indicates a lack of confounding circadian variability for these markers during the course of the biliary function study. Biliary excretion patterns of these marker solutes (e.g., rapid high recoveries of phenolphthalein glucuronide and low concentrations of Pi and glucose) demonstrated that our system for bile function studies is associated with intactness of the examined pathways of bile formation. These results validate our system and set of marker solutes for in vivo biliary function studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Protection by L-2-oxothiazolidine-4-carboxylate, a cysteine prodrug, against 1,1-dichloroethylene hepatotoxicity in rats is associated with decreases in toxin metabolism and cytochrome P-450.

Our objective was to determine if the intracellular cysteine precursor, L-2-oxothiazolidine-4-carboxylate (OTZ), would protect rats against the hepatotoxicity of 1,1-dichloroethylene (DCE) by altering the toxin's biologic fate. Fasted male rats were pretreated with 10 mmol of OTZ per kg s.c. in saline or with saline only 1 hr before administration of 14C-labeled DCE (50 mg/kg) p.o. in mineral oil. Serial blood samples were taken from permanent jugular cannulas between 1 and 24 hr to monitor the time course of injury and circulating levels of 14C-derived label. DCE caused less liver injury in the OTZ-pretreated group. This protection was associated with about 50% less total, acid soluble and acid precipitable 14C-label in serum; 30% less label in urine; and at 24 hr, 30 to 68% less covalently bound label in liver, kidney and lung. Extent of peak liver injury in individual animals correlated well with the amount of 14C-label in serum at early times and with the amount covalently bound to liver at 24 hr, but correlated poorly with label excreted into urine. An explanation for the apparent decrease in DCE metabolism by OTZ-pretreated animals was investigated by examining effects of OTZ on liver constituents known to have a role in DCE metabolism. Fasted rats given 10 mmol of OTZ per kg showed a persistent loss of hepatic cytochrome P-450 at 3 and 6 hr whereas their hepatic and renal reduced glutathione contents were transiently diminished at 3 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

A stable colorimetric assay to measure toxin elevation of inorganic phosphate in bile.

A modified assay for the measurement of nanomole amounts of Pi in 50 microliters of bile is described. The assay is based on the formation of a complex between malachite green dye and phosphomolybdate under acidic conditions. Only three simple steps are required to produce a colored complex which remains stable for at least 3 h; these steps are precipitation with acid, addition of color reagent containing dye and surfactant, and incubation at 37 degrees C. Analysis of bile samples collected from a rat given the toxin 1,1-dichloroethylene demonstrated that the assay is well suited to routine assays of biliary Pi as an endogenous indicator of aberrant hepatobiliary function.

Animals↗
PubMed1988

Potentiation of 1,1-dichloroethylene hepatotoxicity: comparative effects of hyperthyroidism and fasting.

The responses of fed, fasted, and hyperthyroid (T4) Sprague-Dawley male rats to 50 mg 1,1-dichloroethylene (1,1-DCE)/kg were compared. Hyperthyroid rats received three sc injections of thyroxine (100 micrograms/100 g) at 48-hr intervals; all other rats were sham-injected. 1,1-DCE was given po in mineral oil 24 hr after the last T4 dose; controls received only mineral oil. Animals were killed at 2, 4, and 8 hr. Liver GSH contents were lowered about 55% by both fasting and T4 while GSH transferase activities were lowered about 20% by fasting and 35% by T4. Only T4 pretreatment lowered alcohol dehydrogenase activities. Liver injury (i.e., serum glutamate pyruvate transaminase, histology) after 1,1-DCE was minimal in fed rats, moderate in fasted rats, and intermediate in T4 rats. Fasted rats showed a more pronounced depletion of liver GSH after 1,1-DCE than T4 rats and only in fasted rats did the toxicant decrease activities of the detoxification enzymes. Hypoglycemia after 1,1-DCE occurred in fed rats, but more rapidly in T4 rats. In contrast, fasted rats unexpectedly became hyperglycemic after the toxicant. Patterns of body temperature change after the toxicant, which might be due to its metabolites, were dissimilar. Hypothermia was not observed in fed rats, was only transiently evident in T4 rats, but occurred rapidly within 1 hr in fasted rats and steadily became more severe. The dissimilar patterns of liver enzyme and body temperature and serum glucose change after the toxicant in the three groups are indicative of different pathways of injury potentiation by fasting and hyperthyroidism.

Alcohol Dehydrogenase↗
PubMed1979

Efficacy of salinomycin and stenorol against various species of Eimeria and effect on chick performance.

Three experiments were designed to test the efficacy of salinomycin and stenorol against infection by various Eimeria species on cage reared broiler type chicks. Efficacy was based on a coccidial index. Sixty parts per million salinomycin alone or in combination with 50 ppm 3 nitro significantly improved the index over basal treatments or when 3 nitro was used alone. The differences in index values recorded for coban and salinomycin were not significant. Stenorol significantly improved the index and appeared to be a most effective anticoccidial product. Broiler chickens reared in floor pens to 8 weeks showed a significant reduction in weight gain when the diet contained salinomycin +3 nitro or coban. Stenorol at 3, 6, or 9 ppm reduced body weight, with linear regression for this effect being highly significant (P less than .01). No coccidiosis was observed.

Animals↗
PubMed1978

Leg bone abnormalities and histopathology of caged and floor reared broilers fed diets devoid of selected vitamins and minerals.

Summers et al., 1978, described an experiment in which performance and leg conditions of birds fed diets devoid of synthetic biotin, choline, folic acid, manganese, and miacin were observed and recoreded. This is a report on birds from the same experiment. Dyschondroplasia of the tibia was documented and the distal end of each tibia examined histologically. Metatarsal length and condyle depth of the distal tibia were also determined. Metatarsal length was influenced by vitamin deficiencies as well as the type of floor on which binds were raised. The depth of the intercondyle space was affected more by a manganese deficiency than by vitamin deficiencies and, in this case, was greater on plastic and litter as opposed to wire floors. There did not appear to be a correlation between the space depth and slipping of the tendons; however, a large number of birds should be examined to provide more data. Dyschondroplasia was more prevalent in choline deficient birds, particularly those birds raised on litter or plastic floors. Histology changes in relation to nutrient deficiencies were comparable to those reported previously.

Animals↗
PubMed1976

Dietary salt and round heart disease in turkey poults with a note on the minimum level of supplementary salt necessary in corn-soybean diets.

Round heart disease in turkey poults has been associated with high levels of dietary salt and when it occurs in the field recommendations often include a reduction in the level of dietary salt. Poults fed diets containing up to 1.5% salt and 1.5% sodium did not exhibit signs of round heart disease. A high mortality rate occurred with poults fed a salt-free diet. Post-mortem analysis generally revealed enlargement of the kidneys with urates; exudate was present in both abdominal and thoracic air sacs. Growth trials indicated that in order to maintain an optimum feed:body weight gain ratio, corn-soybean diets should contain at least 0.1--0.2% supplemental salt, and at least 0.2--0.3% salt when growth rate is considered. Minimum salt levels could not be reduced further by adjustment of the total dietary sodium:chloride ratio to unity.

Animal Feed↗
PubMed1975

The effects of elevated levels of sodium chloride on ascites and related problems in turkeys.

The response of young poults to diets containing 0.7, 1.2, 1.7 and 2.7 per cent sodium chloride was studied. Water intake, feed intake and wieght gain were not significantly influenced by treatment. Only the highest level caused a significant increase in mortality. Ascites was not a consistent finding even on high levels of salt. A straight line best described the response but confidence limits were large and this was also true for heart, kidney and lung lesions. Lesions showing myocardial distension with pericardial adhesions, severe congestion of the lungs and enlarged pale kidneys seemed more indicative of salt intoxication than classic ascites. Microscopically heterophilic (eosinophilic) lung and meningeal infiltrates accompanied by myocardial degeneration and adhesions were suggestive, but not specific, of salt intoxication.

Administration, Oral↗
PubMed1975

Studies on the control of Mycoplasma gallisepticum in hatching eggs.

Lincomycin-spectinomycin, while effective in eliminating Mycoplasma gallisepticum from hatching eggs when administered via the yolk sac, had a marked deleterious effect on hatch-ability when given by this route. On the other hand when lincomycin-spectinomycin was injected into the air cell there was a reduction in the level of experimental infection with an acceptable effect on hatchability.

Animals↗