Urinary aspartate transaminase in normal children and children with various renal diseases including orthostatic proteinuria were determined. The mean values of urinary aspartate transaminase activities in healthy, nephrotic, acute nephritic and orthostatic proteinuric children were found to be 12.9±7.2, 53.0±38.4, 115.8±66.6 and 100.3±63.4μmoles oxaloacetate formed per hour in 24-hour urine, respectively.
In orthostatic proteinuria, the enzyme level in urine together with urinary protein excretion was almost equal to ther values obtained from nephritic children. On the basis of these observations, a possible pathogenesis of orthostatic proteinuria was discussed.
Determination of urinary aspartate transaminase activity was found to be of use for the differential diagnosis of renal diseases. An isoenzyme nature of urinary transaminase was also studied.

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Serine dehydratase activity which resides in homoserine dehydratose protein as well as homoserine dehydratase and cystathionase activity is strongly inhibited by alanine.

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The activation of thiaminase I with various substances was investigated. It was observed that the purified bacterial thiaminase I, which was separated from some activators, and crude shell-fish thiaminase I could be activated with nicotinic acid. It was recognized that some basic amino acids and some others activate the enzyme reaction, although, in some cases, the rate of the activation is not significant.
Pyrimidinyl-nicotinic acid (Pm-NiA) in the reaction mixture of thiamine, nicotinic acid, and bacterial thiaminase I was detected by paper chromatography. To determine the amount of Pm-NiA produced in the reaction, a chemical assay of Pm-NiA was developed. Using this method, the best conditions for the enzyme reaction were established.
Pm-NiA was isolated by column chromatography using Amberite CG-50, as a decomposition product of thiamine by the purified bacterial thiaminase in the presence of nicotinic acid. The yield of Pm-NiA was about 71% of the amount formed in the reaction mixture as estimated by the chemical assay. The isolated crystals showed mp 233° and Rf 0.39 (n-butanol:methanol:water, 2:1:1). Ultraviolet absorption maximum was at 245mμ (pH 2), and 230 and 270mμ (pH 9), in agreement with those of chemically synthesized Pm-NiA.

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1. The absorption tests of tritiated folic acid (³H-FA) and ⁶⁰Co-cyanocobalamin (⁶⁰Co-B₁₂) were carried out in normal subjects and patients with gastrointestinal or hematological diseases.
2. An oral dose of 40μg ³H-FA per kg of body weight was given 30 minutes after an injection of 15mg of non-radioactive FA. The urinary excretion of ³H-FA was estimated in following 24 hours. In some cases the fecal excretion of ³H-FA was measured for successive four days.
3. The urinary excretion of ³H-FA in eleven normal subjects ranged from 37.6 to 57.9 per cent of the oral dose, with a mean of 48.4 per cent and a standard deviation of 7.4 per cent. The fecal excretion ranged from 1.5 to 7.5 per cent of the dose with a mean of 3.5 per cent and a standard deviation of 3.5 per cent.
4. In some cases of gastrectomy, defective FA absorption was observed.
5. Decreased urinary excretion was found in patients with blind loop syndrome and also in some case of ileocolostomy.
6. Urinary excretion of ³H-FA was diminished in some cases of hematological disorders, such as pernicious anemia and leukemia.
7. The causes of defective FA absorption were discussed in each case.

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1. The site and mechanism of folic acid (FA) absorption were studied in the rat, using ³H-FA.
2. After intragastric administration of 40μg of ³H-FA per kg of body weight, 79.3 per cent of the administered dose was absorbed from the upper gastrointestinal tract in 6 hours.
3. From the jejunal loop, 91.7 per cent of the injected dose was absorbed in 6 hours, and the absorption from the ileum was about 50 per cent of that from the jejunum.
4. With the increase of administered doses, the rate of absorption was decreased, while the absolute amount of the absorbed FA increased almost linearly.
5. The absorption of FA was not affected by the following conditions: simultaneous administration of Amethopterin or dinitrophenol, pretreatment with Amethopterin or FA, and deficiency of FA.
6. The site and mechanism of FA absorption were discussed and a passive transport for FA was suggested.

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1. The plasma clearance and urinary excretion of ³H-FA were observed in normal subjects and patients with hematological and hepatic diseases.
2. ³H-FA in a dose of 20μg per kg of body weight was intravenously injected. The plasma clearance was observed for 6 hours and the urinary excretion for 12 hours.
3. In 6 control subjects, ³H-FA in the plasma was 13.06, 7.05, 4.51, 3.08, 2.14, 1.59 and 0.41 per cent of the dose per liter of plasma 5, 15, 30, 60, 90, 120 minutes and 6 hours following the injection, respectively. The urinary excretion of ³H-FA in 12 hours ranged from 16.8 to 31.3 per cent, with a mean of 25.5 per cent.
4. An abnormally rapid clearance and low urinary excretion of ³H-FA were observed in all the cases of pernicious anemia and in almost all the cases of aplastic anemia.
5. In some cases of acute leukemia abnormally rapid clearance and low urinary excretion of ³H-FA were observed, while in patients with chronic leukemia all cases showed an abnormally rapid clearance and low urinary excretion.
6. In patients with acute hepatitis, the results varied from case to case. In some cases of liver cirrhosis and chronic hepatitis, abnormally rapid clearance and low urinary excretion of ³H-FA were observed.
7. Furthermore, organ distribution and urinary excretion of ³H-FA were observed in the rats after intravenous administration of 50 or 200μg of ³H-FA per kg of body weight.
8. In the rats pretreated with CCl₄, high urinary excretion and low hepatic uptake of ³H-FA were observed in the early stadium, while low urinary excretion and high hepatic uptake were observed in the late stadium. These results were in good agreement with those of patients with acute hepatitis.
9. In the rats pretreated with Amethopterin, disturbed FA metabolism was proved by low hepatic and renal uptakes, and high urinary excretion of ³H-FA.
10. The causes of abnormal plasma clearance and urinary excretion of ³H-FA in man and abnormal organ distribution in rats were discussed in each case.

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A more precise and sensitive method for the separate determination of Pyrithiamine (PyT) and thiamine in biological materials was described. The method was based on the different behavior of these two compounds toward the oxidation with cyanogen bromide or potassium ferricyanide, and on the different characteristics of the fluorescence spectra of the oxidation products.
Thiamine and PyT in biological materials were extracted by homogenizing and heating in an acidic medium, followed by deproteinization with metaphosphoric acid, adsorption on permutit and elution with hot KCI-HCI. For the determination of PyT, an aliquot of the eluate was oxidized with alkaline ferricyanide (1% in 10% NaOH) and the oxidation product, after extraction into isobutanol, was determined fluorometrically using a spectrofluorometer with an excitation at 430mμ and emission at 460mμ. In the case of the thiamine determination, the same eluate was oxidized with cyanogen bromide and the isobutanol extracted thiochrome was determined at 375mμ exciting and 420mμ emitting wavelengths. The lowest limit of detection for PyT was less than 0.3mμmole, and that for thiamine was less than 0.03mμmole per assay.

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Uptake of pyrithiamine (PyT) by tissues of normal and thiamine-deficient rats was compared.
1. PyT concentration in livers of both normal and thiamine deficient rats reached a maximal level of approximately 20μg/g within 1 hour after the intraperitoneal injection of 10mg/kg of PyT, and then decreased. The rate of decrease of PyT was much slower in the deficient liver than in the normal one. The former retained about 8μg/g of PyT even after 6 days, while the latter retained less than 0.5μg/g.
2. Brain and muscular tissues took up PyT very slowly, and the maximal concentrations were obtained 24 to 48 hr after the injection. PyT levels in these tissues of the deficient rats were markedly higher and maintained for a longer time than that of normal ones.
3. The thiamine levels in tissues of PyT treated normal rats decreased temporarily in accordance with the time of PyT accumulation. In thiamine-deficient tissues except brain, thiamine levels decreased to a very low level and were not further affected by PyT administration. The brain thiamine level decreased by the injection of PyT.
4. The increased PyT levels of PyT treated thiamine-deficient rats were quickly decreased by the administration of thiamine.
5. Most of the PyT taken up by the tissues of thiamine-deficient rats was present as the phosphorylated form.
6. When an equimolar amount of PyT or thiamine was administered to thiamine-deficient rats, more PyT was taken up by the tissues than thiamine. Coadministration of PyT and thiamine caused reduction of the uptake of both compounds.
7. The mechanism of the thiamine lowering action of PyT was discussed.

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