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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology
Effect Of Altitude On The Peripheral Degradation Of Thyroxine In The Uinta Ground Squirrel (Citellus Armatus), Stuart K. Ware
Effect Of Altitude On The Peripheral Degradation Of Thyroxine In The Uinta Ground Squirrel (Citellus Armatus), Stuart K. Ware
Theses and Dissertations
Various methods were employed to detect changes in the peripheral degradation of thyroxine (T4) in adult Uinta ground squirrels (Citellus armatus) collected at two different altitudes (5400 and 9000 feet.) Plasma half-life of injected T4-125I (tl/2) was significantly decreased with altitude, as was T4-125I distribution space (TDS) and T4 degradation and secretion rate (TSR). In vitro deiodination of T4-125I by heart homogenates was not affected, while urinary excretion of thyroxine derived iodide was increased at high altitude 44-70 hours post-injection. Both total and free serum T4 concentrations were reduced at high altitude, although not significantly. The cause of the reduced …
The Effect Of Altitude On Thyroid Function Of The Uinta Ground Squirrel (Citellus Armatus), Wendell Lee Wells
The Effect Of Altitude On Thyroid Function Of The Uinta Ground Squirrel (Citellus Armatus), Wendell Lee Wells
Theses and Dissertations
Thyroid uptake and distribution of 125I, concentrations of T4 and T3 in serum and thyroids and concentrations of TSH in serum and pituitaries were measured to determine thyroid function of Uinta Ground Squirrels (Citellus armatus) native to 5,400 and 9,000 feet elevations to evaluate alterations in the state of the thyroid due to increased altitude. Uptake of 125I was 60 percent lower by squirrels from 9,000 feet. Incorporation of 125I into T3 was greater at the higher elevation, but absolute thyroid T3 concentrations were similar at both elevations. No significant differences were found in serum T3 concentrations, but squirrels living …
Absorption Of Caffeine Through Isolated Rat Small Intestine, William James Hatch
Absorption Of Caffeine Through Isolated Rat Small Intestine, William James Hatch
Theses and Dissertations
Intestines of fifty-six albino rats of the Holtzman strain were removed and perfused with Krebs bicarbonate buffered solutions containing caffeine. After one hour of absorbtion, caffeine was extracted from the serosal fluids in chloroform and concentrations were determined spectrophotometrically. It was found that all portions of the small intestine transported caffeine against a concentration gradient. This transport mechanism demonstrated saturation kinetics and was inhibited by ouabain. It was concluded that the movement of caffeine from the mucosa to the serosa of the small intestine cannot be the result of simple diffusion. Possible mechanisms by which the absorption of caffeine takes …
The Effects Of Thiamin Deficiency And Thiamin Antagonists On Cardiac Function In The Rat, D. James B. Sutherland
The Effects Of Thiamin Deficiency And Thiamin Antagonists On Cardiac Function In The Rat, D. James B. Sutherland
Theses and Dissertations
A study was made to determine what biochemical changes were involved in the slowing of the rat heart rate during thiamin deprivation, pyrithiamin or oxythiamin treatment. The appearance of bradycardia during progressive thiamin deficiency was shown to be related to the reduction in myocardial enzymatic activity of pyruvate (PDH) and 2-ketoglutarate (2-KGDH) dehydrogenase, and not due to inanition alone since pair-fed control rats did not show bradycardia until the agonal stage. Bradycardia was not the result of reduced energy since CP, ATP, ADP, and AMP levels remained normal even though PDH and 2-KGDH activity dropped to 20% of normal by …
Autoradiographic Studies Of The Distribution Of Serotonin In The Rat Brain, Brent D. Wagstaff
Autoradiographic Studies Of The Distribution Of Serotonin In The Rat Brain, Brent D. Wagstaff
Theses and Dissertations
Serotonin (5-hydroxytryptamine, 5-HT), considered to be a synaptic transmitter within the central nervous system, has been shown to be localized mainly in the paleocortex of the brain. Others have shown disturbances of normal 5-HT metabolism to be associated with mental illness and disease. Attempts to inject tritium labelled 5-HT into cerebrospinal fluid of the rat brain for anatomical localization studies were·made. The following observations were noted, (1) there exists a perivascular space in which fluid flows and distribution is relatively uninhibited as compared to subarachnoid space, (2) the labelled 5-HT penetration of brain tissue parenchyma is restricted and radioactivity is …
Effect Of Exercise On Tissue Concentrations Of Thyroid Hormones And On Thyroxine Degradation Rate In The Rat, William W. Winder
Effect Of Exercise On Tissue Concentrations Of Thyroid Hormones And On Thyroxine Degradation Rate In The Rat, William W. Winder
Theses and Dissertations
Several methods were used to detect changes in thyroid activity and in degradation of thyroxine (T4) in exercising and sedentary control rats. Rats were run in a motor-driven exercise wheel over a three-week period at progressively increasing work loads and then were run 1.5-2 hours per day for 10-14 days before sacrifice. Disappearance of injected T4-125I from plasma was considerably enhanced by exercise. As determined by isotopic equilibration and paper chromatographic methods, T4 concentration was depressed in plasma and elevated in liver of exercised rats. No significant changes in T4 concentration were observed in heart, kidney, or gastrocnemius muscle. Thyroidal …