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Biomedical subjects

D Duncan

Publications and source records attributed to D Duncan.

At least 91 records · Page 5Linked to original sources
PubMed1975

Specialized contacts of astrocytes with astrocytes and with other cell types in the spinal cord of the cat.

Adult and half grown healthy male and female cats were used in this study. The white and gray matter of dorsolateral region in the upper lumbar levels of the spinal cord were examined by electron microscopy after fixation by aldehyde perfusion and commonly used methods of embedding, sectioning and staining. The report is limited to description and illustration of specialized junctions of astrocytes. In addition to previously described astrocyte-astrocyte gap junctions, astrocytes are connected by gap junctions to oligodendroglia cells and to neurons. Astrocytes also are connected with each other and with neurons by juctions characterized by wide (250 A) gaps containing opaque gap material and by dense material adhering to the inner surfaces of the plasma membranes. The results suggest a morphological basis for adhesion and intercommunication between all adult derivatives of the embryonic neural tube.

Animals↗
PubMed1975

Effect of aminoglutethimide on serum progesterone and estrogen in the pregnant baboon (Papio SP).

AG was administered orally twice daily for 1 or 3 days to six baboons whose duration of pregnancy ranged from 31 to 99 days. Serum progesterone levels were reduced to as little as 3.2% of the initial concentration in one animal and to 20% or less in four of the five remaining baboons. Serum estrogen levels were depressed by 50% or more in three of the four animals in which they were measured. However, pregnancy ensued for at least 3 wk after treatment in all animals. The data suggest that peripheral blood levels of sex steroids may not reflect the critical concentration of hormones required at the uteroplacental juncture for the successful pregnancy maintenance.

Abortion, Spontaneous↗
PubMed1970

Otoplasty.

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Ear↗
PubMed1970

Effects of sinus nerve stimulation on carotid body glomus cells.

The sinus nerve or sympathetic trunk was stimulated unilaterally in one group of adult cats or Syrian hamsters while in another group the sinus nerve or sympathetic trunk was cut unilaterally and the animals were given reserpine. In a third group, atropine was administered prior to sinus nerve stimulation. All tissues were processed for the detection of primary monoamines. The carotid bodies on the operated sides were compared with those on the unoperated sides of the same animal in order to determine if amine depletion occurred following the experimental procedures. After sinus nerve stimulation alone, the density of the granules in the glomus cells was decreased, but changes were not noted in the granules following sympathetic nerve stimulation. Sinus nerve stimulation after atropine administration resulted in no change in granule density. Sinus nerve transection followed by reserpine treatment resulted in a greater decrease in granule density on the unoperated than on the operated side. Transection of the sympathetic components to the carotid body followed by reserpine injections resulted in a decrease in granule density in the glomus cells on both the operated and unoperated sides. These results suggest that the sinus nerve must be intact for reserpine to exert an effect and that the sinus nerve may contain efferent fibers which modulate amine secretion.

Amines↗