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Biomedical subjects

C Duncan

Publications and source records attributed to C Duncan.

At least 91 records · Page 5Linked to original sources
PubMed1981

Effects of tomato pomace and mixed-vegetable pomace on serum and liver cholesterol in rats.

The effects of tomato pomace and mixed-vegetable pomace, vegetable processing by-products, on serum and liver cholesterol were compared against pectin, wheat bran, cellulose, and lignin. Male Sprague-Dawley rats (100 g) were fed high sucrose, semi-purified diets containing basal (0), 5% or 10% of the fiber source and either 0, 0.5% cholesterol or 0.5% cholesterol + 0.125% sodium cholate. After 28 days, there were highly significant differences (P less than 0.001) in serum and liver cholesterols due to fiber source, dietary cholesterol and the interaction. The effect of fiber source level was significant (P less than 0.05) for liver cholesterol only. Pectin groups had serum and liver cholesterol levels lower (P less than 0.05) than the others. At the 10% level, tomato pomace, wheat bran and lignin (Indulin AT) groups had serum cholesterols higher (P less than 0.05) than basal; the mixed-vegetable pomace and cellulose groups were not different from basal. Liver cholesterols of tomato pomace, mixed-vegetable pomace, wheat bran and lignin groups were not different at the 10% level, but were higher than the pectin, cellulose and basal groups (P less than 0.05). In a second experiment, serum cholesterols of rats fed pectin were lower (P less than 0.05) than for those fed cellulose or two types of lignin (Indulin AT, Reax 27).

Animals↗
PubMed1981

Paraplegia due to peripheral venous air embolus in a neonate: a case report.

A term male infant with pneumonia was receiving fluid and antibiotics through an intravenous line in the scalp. Air was accidentally infused in this line. Subsequently, discoloration of the skin, a flaccid paraplegia, hematuria, and gastrointestinal bleeding occurred as the presumed effect of venous air entering the systemic arteries. The umbilical vessels were never catheterized. Absence of any apparent cerebral air embolism is interpreted as being due to the infant's position (head down) at the time of air infusion. The pathogenesis and prevention of this tragic complication are discussed.

Anti-Bacterial Agents↗
PubMed1980

A critical evaluation of tetrahydroisoquinoline induced ethanol preference in rats.

It has been reported that certain tetrahydroisoquinoline compounds, especially salsolinol and tetrahydropaveroline (THP) when infused into the lateral ventricle of rats' brains results in increased preference for alcohol solutions. The effect is reported to be long-term, in that animals do not return to baseline drinking even months later. The current report provides a replicatin of the original experiments and also an extension of the work to complete dose-response curves for salsolinol and THP. Generally we have confirmed that rats of the Sprague-Dawley and Long-Evans strains do increase their alcohol intake in response to infused THP or salsolinol and that the effect is long lasting, up to 10 months. Such animals consume less alcohol at concentrations above 20% than below, in contrast to the previous reports where drinking was maintained at high concentrations of alcohol. While the animals will select alcohol in the face of a saccharin choice, they will not drink alcohol adulterated with quinine. We have failed to observe signs of dependence or withdrawal by these techniques and suggest that the original reports of these signs may have been a result of cellular damage caused by the long-term infusions. Additionally we have carried out extensive dose-response experiments with both salsolinol and THP. Doses of THP of 104 nmoles/day were inhibitory to alcohol drinking. We conclude that these compounds do shift these animals preference for alcohol relatively permanently, but not to the point of gross intoxication nor into the highly aversive range of alcohol concentration. We cannot confirm the reports that salsolinol or THP produce withdrawal symptoms when infused.

Alcohol Drinking↗
PubMed1979

RNA polymerase III transcriptional units are interspersed among human non-alpha-globin genes.

Cloned human DNA fragments containing globin genes are transcribed in vitro to form discrete RNA species. One transcription unit is located approximately 1500 base pairs upstream from the G-gamma-globin gene. This transcript is partially homologous to a polymerase III template located approximately 1000 base pairs upstream from the delta-globin gene and to DNA located a short distance downstream from the beta-globin gene.

Cloning, Molecular↗
PubMed1978

Possible sites of temperature-dependent changes in sensitivity of the positive inotropic and chronotropic responses to sympathomimetic amines by comparisons of the temperature optima for a range of agonists.

The temperature optimum for the positive inotropic response of guinea-pig isolated atria to single submaximal doses of isoprenaline was 25 degrees C. This was well separated from that for rate responses (37.5 degrees C). This separation was not due to changes in catechol-0-methyl-transferase or phosphodiesterase activity since it occurred with orciprenaline alone and in the presence of theophylline. The rate optima for aminophylline, histamine, glucagon, ouabain, calcium chloride and dibutyryl cAMP were essentially the same as for isoprenaline. The temperature-dependences therefore lie at a common ultimate pathway leading to the rate response. The site of temperature-dependence of the inotropic response to isoprenaline is not at the common contractile mechanisms since its optimum differed from those of ouabain and CaCl2. Activity of cAMP and its production were also eliminated as possible sites from differing optima of aminophylline, histamine and dibutyryl cAMP. The temperature-dependence may lie at the beta-adrenoceptor itself, possibly adenyl cyclase. This may be shared by glucagon although tachyphaylaxis made its optimum difficult to determine.

Animals↗
PubMed1977

The influence of temperature upon reserpine-induced supersensitivity of guinea-pig isolated atria to isoprenaline and salbutamol.

1. The aim of this investigation was to determine whether supersensitivity of isolated atria to sympathomimetic amines following pretreatment with reserpine was evident at low temperatures, which alone induced supersensitivity. 2. Cumulative dose-response curves for the positive inotropic and chronotropic responses of isolated guinea-pig atria to isoprenaline and the partial agonist salbutamol were plotted as a percentage of the maximum response to isoprenaline. 3. In atria from reserpine-pretreated guinea-pigs set up at 38 degrees C, supersensitivity of both rate and tension responses was observed as a shift of the curves to the left and an increase of the maximum responses to salbutamol. Tension responses were potentiated more than rate responses. At 30 degrees C the supersensitivity became less apparent and at 25 degrees C was virtually absent. 4. The dose-response curves in untreated atria at low temperatures revealed that hypothermia itself produced supersensitivity of rate and tension responses. The dose-response curves were displaced to the left and the salbutamol maxima were raised so that at 25 degrees C it became almost a full agonist. The hypothermia-induced supersensitivity was therefore sufficient to mask any supersensitivity resulting from pretreatment with reserpine. 5. The hypothermia-induced supersensitivity of the rate response was dependent upon the method of plotting. When plotted in absolute units of beats per min no supersensitivity of the rate response was evident. Supersensitivity of the tension response at the lower temperatures and of both rate and tension responses following pretreatment with reserpine were independent of the plotting method.

Albuterol↗
PubMed1977

Atelencephalic microcephaly.

A two-month-old child born with marked microcephaly (head circumference 17cm) was found at autopsy to have gliomesodermal tissue replacing the telencephalon (atelencephaly). This finding, together with genital anomalies and hypoplasia of the extremities, suggests arrest at the fifth week of fetal life. The clinical and pathological features are described and the pathogenesis is discussed.

Abnormalities, Multiple↗