Methotrexate: studies on cellular metabolism. IV. Effect on the mitochondrial oxidation of cytosolic-reducing equivalents in HeLa cells

The effect of methotrexate (MTX) on the mitochondrial oxidation of cytosolic-reducing equivalents in HeLa cells was studied. MTX inhibited (100 per cent) malate dehydrogenase activity, but no effect was observed on that of GOT. MTX (0.5 mM) inhibited (100 per cent) the activity of reconstituted enzymatic system MDH-GOT, probably as a consequence of inhibition of malate dehydrogenase activity. MTX decreased pyruvate production (54 per cent), demonstrating its inhibitory action on the malate-aspartate shuttle. Blockage of the malate-aspartate shuttle by MTX accounts for the decrease in cellular energetic gain. The results obtained are consistent with the view that in HeLa cells, as well as in other tumour cells, the transport of reducing equivalents from cytoplasmic NADH into the respiratory chain of mitochondria is via the malate-aspartate shuttle.     

Inhibitory effect of hirudin on thrombosis induced by prothrombin complex concentrates

The influence of hirudin on thrombus formation induced by prothrombin complex concentrate (PCC) was studied in two different test series in rats. Within the first test series hirudin was i.v. administered to the animals 10 min before they received PCC. Complete prevention of thrombus formation required a hirudin dose of 0.2 mg/kg. Within the second test series hirudin was added to the transfusion unit of PCC before application of PCC was started. In this case complete prevention of thrombus formation was yielded by addition of 140 micrograms hirudin to the PCC transfusion unit. In comparison with heparin and the synthetic thrombin inhibitor N alpha-(2-naphthylsulfonyl-glycyl)-4-amidinophenylalanine piperidide, hirudin was most potent.     

Release of plasminogen activator by pentosan polysulfate

In isolated perfused organs (pig ear, rabbit ear, rat lung) pentosan polysulphate caused an increase in the release of plasminogen activator. The activator was released in a dose-dependent manner, the release being repeatedly induced as demonstrated with the rabbit ear. An increase in activator activity was also found in experimental animals (mini-pig, rat, rabbit). In the isolated perfused organ and the whole animal, the activator released proved to be tissue-type plasminogen activator. For the release mechanism displacement of mural plasminogen activator by pentosan polysulphate seems to be of importance. The release of tissue-type activator plays a decisive role for the regulation of the temporarily insufficient fibrinolytic system, for the thrombolytic process and for the antithrombotic action of pentosan polysulphate.     

Study of the growth and development of chlorella populations in the culture as a whole

Использование haematoxylin и Feulgen в реактив было продемо нстрировано, что клет ки виды Chlorella pyrenoidosa и Chlorella vulgaris после довательно пройти че рез полиядерных этап а в течение их жизни ц икла. Polynuclearity не связан с уче том размера ячейки. Ин дивидуальные Клетки нормальной культуры Показать отмеченные cytomorphogenetic разногласий. Далее научных исследовани й по данному вопросу н е требуется.     

Fibrinolytic properties of a heparin-ocrase complex]

The obtained heparin-ocrase complex includes properties of inhibiting coagulation and a high fibrinolytic activity in vitro and in vivo. The fibrinolytic activity of the heparin-ocrase complex is higher than the equivalent amount of ocrase. The fibrinolytic activity of the complex is not only evident on non-stabilized fibrin plates, but likewise on stabilized ones and at the presence of inhibitors of enzymatic fibrinolysis, such as Trasylol and epsilon-aminocaproic acid. The complex formation between heparin and protease was confirmed by means of cross-paper electrophoresis and spectrophotometry.