Boxer

McHenry

Schoenheimer

Soskin

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Synthesis of fat from carbohydrate in thiamine deficiency

Gruber, M.

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Utrecht University Repository

480 SHORT COMMUNICATIONS, PRELIMINARY NOTES VOL. 7 (1951) REFERENCES 1 R. Y. STANIRR, J. Baa., 54 (1947) 339. J. L. KARLSON AND H. A. BARKER, J. Biol. Chem., 175 (1948) 913. s S. J. AJL, J. Baet., 59 (195 o) 499. 4 MONOD, La Croissance des cultures bactdriennes, Hermann, Paris (1942). 5 H. A. KREES AND K. HENSELEIT, Z. physiol. Chem., 21o (1932) 33. H. A. KREBS, L. V. EGGLESTON, AND R. HEMS, Biochem. J , 43 (1948) 4 °6. s D. BONNER, Cold spring Harbor Symposia Quant. Biol., I I  (1946) 14. 7 M. ROLOFF, S. RATNER, AND R. SCHOENHEIMER, J. Biol. Chem., 136 (194 o) 561. 8 j .  R. S. FINCHAM, J. Biol. Chem., 182 (195o) 51. 9 M. R. STETTEN AND R. SCHOENHEIMER, J. Biol. Chem., 153 (1944) 113. 10 D. SHEMIN AND D. RITTENBERG, J. Biol. Chem., 158 (1945) 71. Received July 3rd, 1951 SYNTHESIS OF FAT FROM CARBOHYDRATE IN THIAMINE DEFICIENCY by M. GRUBER Laboratory o/ Physiological Chemistry, The University, Utrecht (Netherlands) A number of papers published by Mc HENRY and his collaborators 1, ~, s have led to a wide-spread acceptance of the view that  the synthesis of fat from carbohydrate is impaired in thiamine deficiency. The evidence put forward by these authors to substantiate his claim is, however, inconclusive. In most of their experiments he groups of rats and pigeons compared had consumed ifferent amounts of food and only one experiment is published in which paired feeding of a fat-free diet was applied to rats (Ref. i, p. 294). As only the mean results of this experiment are stated it is impossible to decide whether or not the small difference observed between the means is statistically significant. BOXER AND STETTEN 4, using the incorporation of deuterium into the body fatty acids of rats as a measure of fat synthesis, arrived at the conclusion that the failure of synthesis and deposition of fatty acids in thiamine deficient rats "is attributable chiefly to the diminished food intake rather than to any specific action of thiamine". Whether any specific action of thiamine xists at all cannot be decided as the amount of food consumed was the l imiting factor in these experiments. Therefore we have carried out experiments on pigeons with forced feeding of large amounts of carbohydrate. In a first experiment 3 o pigeons received 2 g thiamine-free casein and 18 g sucrose daily, supplemented with a salt and vitamin mixture including thiamine. After 18 days ten animals were sacrificed and their fat contents determined (Group I) ; half of the remaining number continued on this food (Group II), while the others received the same food, but with omission of thiamine (Group III). When, after 14 days, symptoms of thiamine deficiency appeared in the animals of Group III, all animals of Groups II and I I I  were sacrificed. The mean figures for the fat contents found are 36.9 g (9.3% of body weight) for Group I, 44.6 g (lO.3%) for Group II, and 43.6 g ( I I .5%) for the thiamine deficient Group III, The differences between these figures are not statistically signi- ficant. Presuming that  the carbohydrate ingested is at least partly metabolized via fatS, s, one should conclude that  the synthesis of fat from carbohydrate is not impaired in thiamine deficiency. In a second experiment with 24 pigeons, which had been subjected to semi-starvation (i order to exhaust their fat deposits) and to partial depletion of the thiamine pyrophosphate stores of their tissues, a direct proof of unimpaired fat synthesis with a net increase of fat content in thiamine- deficient pigeons could be given. The pigeons were divided in three groups of eight pigeons each, numbered IV, V and VI. Group IV was sacrificed after the starvation and depletion period ; Group V received 3 g casein and 24 g sucrose daily with salts and vitamins, including thiamine in abundance. Group VI received the same food without thiamine. When, after six days, the animals of Group VI showed grave symptoms of thiamine deficiency all animals were sacrificed. Thiamine pyrophosphate determinations in the hearts showed that during this period Group VI had a moderate to grave VOL. 7 (1951) SHORT COMMUNICATIONS, PRELIMINARY NOTES 48I  thiamine deficiency, while Group V was normal. The fat contents were 2.1 4- O. I8"$/0 for Group IV; 4.3 4- o.93~/o for Group V and 3.7 4- o.44~/o for Group VI. These figures demonstrate hat both Groups V and VI had synthesized fat from carbohydrate (P values for differences with Group IV < o.o 5 and < o.oi respectively). Their mutual difference has no statistical significance whatever (P > o.5). Hence neither of these experiments has given the slightest indication that thiamine deficiency causes an impairment of the synthesis of fat from carbohydrate. This work forms part of investigations onthe metabolism and physiological function of thiamine carried out by H. G. K. WESTENBRINK and collaborators. Full details and discussion will appear shortlyL REFERENCES I E. W. MCHENRY, J. Physiol., 89 (1937) 287. 2 E. W. MCHENRY AND G. GAvin, J. Biol. Chem., I25 (1938) 653. 8 E. W. MCHENRX" AND G. GAvin, J. Biol. Chem., 128 (1939) 45. 4 G. E. BOXER AnD DEWITT STgTXlN Jr., J. Biol. Chem., I53 (1944) 6o7. 5 R. SCHOENHEIMER AND D. RITTENBERG, J. Biol. Chem., I14 (1934) 381. 8 S. SOSKIN AND R. LEVlNE, Carbohydrate Metabolism, The University of Chicago Press, Chicago I946, p. lO. 7 M. GRUBER, Aeta Physiol. Pharmaeol. Neerl., in the press. Received July i2th, i951 * Standard eviation of the mean. A RAPID DETERMINATION OF GLYCOGEN IN TISSUES by B. J. VAN DER KLEI J  Laboratory o/Physiological Chemistry, The University, Utrecht (Netherlands) A quick method for the determination of glycogen in tissues has been elaborated by com- bining a rapid procedure of extraction, viz. grinding the tissue sample with sand and trichloroacetic acid, with the very simple spectrophotometric method of glucose determination according to MENDEL ANn HOOGLAND 1. The latter makes use of a pink colour which develops when concentrated sulphuric acid is added to a glucose solution and the mixture is placed in a boiling waterbath for a few minutes. The glycogen eed not be hydrolyzed before performing the glucose determination as 7 minutes' heating with the only slightly diluted sulphuric acid is sufficient o bring about hydrolysis of the glycogen as well as development of the colour. The procedure is described below for the determination i rat liver and muscle tissue. The practically negligible amounts of free glucose present are included in the determination. 1 g of liver is ground in a mortar with I g quartz sand (purified by boiling with potassium bichromate and sulphuric acid) and IO ml of a solution of 5~/o trichloroacetic acid and o.I~o silver sulphate, until a very fine suspension is obtained (this point is reached in about 2 minutes). The suspension is transferred to a volumetric flask of 5 ° mi, the mortar is rinsed with lO ml of the trichloroacetic a id-silver sulphate solution and the volume is made up with water to 5 ° ml. Quartz sand and precipitate are removed by centrifuging. According to MENDEL AND HOOGLAND the glucose determination is carried out by adding x ml glucose solution to 3 ml concentrated sulphuric acid, placing the mixture in a boiling waterbath for 7 minutes and measuring the extinction at 515 m/~. As the most suitable concentrations fora determi- nation are situated between IOO and 2oo ? glucose/ml, the glycogen determination can be carried out in I ml of the trichloroacetic acid-silver sulphate xtract, when the glycogen concentration ofthe tissue does not exceed i ~/o- Extracts with higher contents must be diluted. For muscle the following modifications are introduced in the above-mentioned procedure: 2 g of quartz sand should be used instead of x g; in order to obtain a sufficiently fine suspension it is 

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Synthesis of fat from carbohydrate in thiamine deficiency

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