Hydration reactions of protonated and sodiated thiouracils (2-thiouracil, 6-methyl-2-thiouracil, and 4-thiouracil) generated by electrospray ionization have been studied in a gas phase at 10 mbar using a pulsed ion-beam high-pressure mass spectrometer. The thermochemical data, ΔH(o)n, ΔS(o)n, and ΔG(o)n, for the hydrated systems were obtained by equilibrium measurements. The water binding energ...

The determination of the thyreostatics 2-thiouracil, its derivatives (4-methyl-2-thiouracil, 4-propyl-2-thiouracil and 4-phenyl-2-thiouracil) and methimazole in manufactured dried animal feed by micellar electrokinetic chromatography (MEKC) is described. A 99 +/- 5% extraction yield at the 20 micrograms g-1 level (n = 8) was achieved by shaking the milled fodder with methanol-1 M NaOH (80 + 20)...

2-Thiouracil-containing nucleosides are essential modified units of natural and synthetic nucleic acids. In particular, the 5-substituted-2-thiouridines (S2Us) present in tRNA play an important role in tuning the translation process through codon-anticodon interactions. The enhanced thermodynamic stability of S2U-containing RNA duplexes and the preferred S2U-A versus S2U-G base pairing are appr...

Rat liver homogenate was incubated at 37 degrees C with thyroxine, 3,3',5-tri-iodothyronine, 3,3',5'-tri-iodothyronine or 3,3'-di-iodothyronine. The degradation or accumulation of these compounds was measured by specific radioimmunoassays. (1) Production of 3,3',5-tri-iodothyronine from thyroxine was highest at pH 6.0--6.5 and was markedly stimulated by the addition of dithiothreitol and effect...

Introduction Since the introduction of thiouracil in 1943 antithyroid treatment for thyrotoxicosis has increased widely and has proved safer and more effective in carefully selected cases as the years have passed. Since 1951 carbimazole has been highly favoured in this country, being considered the least toxic agent in large-scale surveys (Burrell, Fraser & Doniach, 1956). Later (Willcox, 1962)...

T HE role of the thyroid gland in the regulation of general body metabo, [ism, metamorphosis, growth, and development is well known.The in. fluence of the thyroid gland and its hormone, thyroxine, upon the amount and distribution of body fat is not thoroughly understood. Although obesity is frequently associated with hypothyroidism in the human, this is not always the case and some hypothyroid ...

Previous studies of the hypothalamus-pituitary-adrenal (HPA) axis in young rodents have found thiouracil-induced hypothyroidism to delay development of the axis past a relative stress non-responsive period. Little attention has been paid to the effects of long-term hypothyroidism on the function of this axis. The present study examined HPA axis response to an acute stress as determined by produ...

The coinparntivc potencies of uracil mid thiouracil in terms of thyroidal changes, hypercholcstcrcinin, azoteniia, and incipient atherosclerosis were determined in rats fed cholesterol and cholic acid. Higher dietary levels of uracil were required to produce changes similar to those seen with thiouracil. Certain dietary components related to uracil were also studied. Orotic acid was found to ha...

Embryonic chick corneas at different stages of development were evaluated for O2 consumption. Some embryos were treated with thyroxine or thiouracil. In untreated animals, corneal QO2 (oxygen consumption/hr./mg. dry weight) decreased from 3.60 at stage 38 to 1.58 after hatching. The temperature coefficient Q10 increased from 1.55 at stage 40 to 2.03 after hatching. If O2 consumption is calculat...