Tryptamine toxicity in adrenalectomized rats; its prevention with tryptamine and hydrocortisone.
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Adrenalectomy↗
Biomedical subjects
W D Denckla
Publications and source records attributed to W D Denckla.
Low temperature urine collector for unstable compounds.
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Animals↗
Systems analysis of possible mechanisms of mammalian aging.
A comparison is made between how bacteria and men use their DNA to accomplish any major biological function. To make this comparison, a modified cybernetic analysis was used. This new type of cybernetic analysis makes a distinction between controlled and regulated systems and may permit an extension of cybernetics into new areas of biology. Prokaryotes have only regulated systems for all major functions, whereas eukaryotes can have both regulated and controlled systems. Several lines of reasoning, including the new cybernetic analysis, suggest that death, as opposed to aging, may be a regulated function in mammals. By analogy with other major regulated developmental functions in mammals, it is also suggested that the hypothalamic-pituitary axis may be the site for the regulation of the time of death. An example of how the pituitary might act on the DNA of peripheral cells to cause possible, severe loss of functional capacity is given by some recent experiments with RNA polymerase activity of liver nuclei from rats of different ages and with different endocrine states.
Aging↗
Restoration of ability to reject xenografts and clear carbon after hypophysectomy of adult rats.
Earlier work suggested that a new pituitary function might account for the decline of minimal O2 consumption with age by decreasing peripheral tissue responsiveness to thyroxine and triiodothyronine. It was of interest to see if removal of the pituitary from adult rats could restore juvenile competence in other systems of the body by reversing the postulated age-associated end-organ hypothyroidism. Four and 64 week old intact rats reject xenografts in 6 and 13.8 days, respectively. After hypophysectomy and thyroxine replacement, 64 week old rats reject xenografts in 6.5 days. Four and 64 week old intact rats have a Vmax of colloidal carbon clearance of 18.9 and 2.5 mg/kg fat free body weight, respectively. After hypophysectomy and thyroxine replacement 60 week old rats have a Vmax of 15.5 mg. Corticosterone was the only other hormone given to the hypophysectomized rats and at the various doses tested it did not appear to affect the rates of the two functions studied.
Age Factors↗