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Before industrial production of thiamine becam possible, among many beriberi patients some showed symptoms of encephalopathy, the cerebral form of the disease. In this animal experiment, thiamine-deficient rats showed failure or blocking of the operant behavior in the maze box, pole climbing box and shuttle box, indicating orientation disturbance and defective memory. This Wernicke's syndrome-like sign dramatically disappeared by treatment with thiamine. Potentiated narcosis with thiopental or alcohol induced in thiamine-deficient rats and mice was readily reversible by thiamine administration. These phenomena are associated with thiamine content of the brain and are found long before histopathological changes in the brain of deficient animals. It is easily surmised that thiamine deficiency in the brain may block the brain metabolism and subsequently cause changes in any chemical substances in the brain, refracting on biophysical phenomenon, such as EEG. However, in the present study, generally speaking, no meaningful results concerning these points were obtained.
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A maximal incorporation of 2-14C-acetate into ubiquinone and ubichromenol was found within 3 hrs if liver tissue homogenate of E-avitaminous rats was incubated for 4 hrs. Phenylalanine, added to the mixture, stimulated the biosynthesis of ubiquinone and ubichromenol in the liver tissue preparations. alpha-Tocopherol caused an increase in biosynthesis of ubiquinone and a decrease in the rate of ubichromenol biosynthesis within 1 hr and 3 hrs of incubation in vitro. The combined addition of phenylalanine and alpha-tocopherol, almost without exceptions, increased the effect of alpha-tocopherol on biosynthesis of the substances studied. Interrelationship is discussed between vitamin E and ubiquinone and ubichromenol biosynthesis.
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A method for determination of pyruvate dehydrogenase activity in mitochondria and tissue homogenates was developed. The method was based on a spectrophotometric monitoring of p-nitroaniline acetylation under conditions required to ensure correct stoichiometric course of the reaction. In rat tissues absolute amounts of the enzyme activity, determined by the method, were found to be several-fold lower as compared with the values determined by the conventional ferricyanide method. Within 24 hrs after a single administration of hydroxythiamin into rats (400 mg per 1 kg of body weight) the pyruvate dehydrogenase activity was decreased 1.5-fold in heart (as estimated by the reaction of p-nitroaniline acetylation) and did not alter in liver tissue. While if the determinations were carried out by the method of terricyanide reduction the enzyme activity was decreas 7- and 2-fold, respectively, in heart and liver tissue. The data obtained suggest that hydroxythiamin impaired reactions of electron transport in tissues; on the other hand, the data obtained showed that the method for determination of the pyruvate dehydrogenase activity, based on the acetylation reaction, was more specific than the conventional method which involved measuring of ferricyanide reduction.
The effect of vitamin A deficiency and hypervitaminosis A on the urothelial carcinogenicity of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formanmide (FANFT) was determined in female weanling Sprague-Dawley rats. Vitamin A deficiency resulted in squamous metaplasia of the urinary bladder and high incidences of cystitis, ureteritis, and pyelonephritis. Administration of FANFT to vitamin A-deficient rats appeared to accelerate the carcinogenic process, with earlier appearance of urinary bladder tumors and the development of ureteral and renal pelvic carcinomas. Most of these tumors were squamous cell, occasionally with transitional cell foci. Hypervitaminosis A prevented the appearance of squamous metaplasia and squamous cell neoplasia in rats fed FANFT, but it did not inhibit the formation of transitional cell hyperplasia or neoplasia in comparison to rats receiving normal levels of vitamin A and FANFT.