The conversion of aneurin into aneurinpryrophosphate by blood corpuscles

1. The in vitro synthesis of aneurinpyrophosphate from added aneurin by the white and red cells of the blood of the rat and of man was studied. Though the synthesis is by no means negligible in human blood it is much higher in rat blood. 2. An average rat leukocyte contains about 160 times as much aneuripyrophosphate as an average rat erythrocyte. This ratio is increased to about 550 upon incubation of the blood with 1 mg aneurin per ml. 3. The synthesis in inhibited by oxalate, monoiodoacetate, fluoride and cyanide. 4. The synthesis by the red cells is preferentially inhibited by oxalate, the synthesis by the white cells by cyanide. This proves that the energy required for the synthesis of aneurinpyrophosphate from aneurin is mainly provided by glycolysis in the red cells and by respiration in the white cells. 5. Upon incubation of the blood with a small amount of aneurin a higher percentage is converted into aneurinpyrophosphate than with a large amount of aneurin. However, even from 0.1 gamma-aneurin added to 1 ml of blood only 26% is phosphorylated (from 1 mg added about 0.25% is phosphorylated). 6. During incubation of rat blood with aneurin at 39°C aneurin is not destroyed, nor are substances formed inhibiting aneurin pyrophosphate synthesis. 7. The synthesis of aneurinpyrophosphate by the erythrocytes depends upon the concentration of glucose present. It is decreased when the glucose concentration is below normal or extremely high. 8. The enzym system responsible for the synthesis of aneurinpyrophosphate from aneurin is badly damaged by incubating the blood at 39°C for some hours. 9. Attention is called to the fact that process producing energy are necessary for the conversion of a certain vitamin into its physiologically active form. As other vitamins form part of various enzymes connected with energy production insight into the interrelationship of various avitaminoses may be gained from investigations on the influence of the lack or one vitamin in the food on the conversion of another vitamin into its physiologically active form

The distribution of aneurinpyrophosphate between the nucleus and the cytoplasm of chicken erythrocytes

The nuclei of chicken erythrocytes contain about 20 times as much aneurinpyrophosphate per unit volume as the cytoplasm

3D buckligami: combinatorial mechanical metamaterials

We present a class of elastic structures which exhibit collective buckling in 3D, and create these by a 3D printing/moulding technique. Our structures consist of cubic lattice of anisotropic unit cells, and we show that their mechanical properties are programmable via the orientations of all unit cells. Collectively buckling, but nonperiodic, structures can be found by solving a combinatorial problem related to spin ice. Such nonperiodic structures present a novel pathway to maximally auxetic, isotropic metamaterials

Programmable mechanical metamaterials

  We present a novel strategy to overcome this limitation and create programmable me chanical metamaterials, where the response of a single structure is determined and can be changed by the amount of lateral confinement.  VICI grant, NWO-680-47-609Biological and Soft Matter Physic

The inhibition of tissue respiration and alcoholic fermentation at different catabolic levels by ethyl carbamate (urethan) and arsenite

1. A hypothesis is given concerning the action of urethan and arsenite on malignant growth. Two assumptionsares made:- (a) the enzyme system responsible for energy production in malignant tumours is working at maximal rate, contrary to the corresponding enzyme system in normal tissues. (b) a given concentration of urethan or arsenite blocks an equal part of the sensitive enzyme(s), by which a measurable effect of a small concentration of these inhibitors on the catabolism will only be obtained in case of maximal turnover rate. 2. Experiments with kidney and liver minces and with yeast have shown that indeed the inhibition caused by urethan and arsenite increases with increasing rate of respiration or fermentation. 3. If the enzyme concentration is not considered to be negligible as compared to the substrate concentration, as is done in the theory of and , the increase of inhibition with increasing turnover number can be made plausible by enzyme kinetics for the much simplified case of one single enzyme. 4. The dependence of inhibition upon the turnover number of the catabolic enzyme system in tumours is discussed in relation to other possible causes of the effect of urethan and arsenite on malignant growth