[Changes in the L-serine and L-threonine dehydrogenase activities in the blood serum of those who worked in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station who became ill with chronic acalculous cholecystitis]. / Izmeneniia aktivnosti L-serin- i L-treonindegidrogenaz v syvorote krovi likvidatorov posledstvii avarii na ChAES, bol'nykh khronicheskim beskamennym kholetsistitom.

Activity was studied of blood serum plasmic enzymes L-serine and L-threonine dehydrogenazes (SDG and ThDG) in 92 liquidators of aftermath of the Chernobyl atomic power plant breakdown, presenting with chronic non-calculous cholecystitis during the stage of moderately severe exacerbation with no clinical and laboratory and sonographic signs of affection of the liver. A quarter of the examinees demonstrated an increased activity of the enzymes under study, which fact is regarded by the authors as a preclinical sign of reactive hepatitis. Recommendations are given as to the outpatient registration and prophylactic management and therapy of those persons having taken part in the elimination of the effects of the Chernobyl accident, presenting with biliary pathologies.

[Estimation of serine- and threonine dehydratase activity of blood serum]. / Opredelenie serin- i treonindegidrataznoi aktivnosti syvorotki krovi.

A procedure for estimation of serine dehydratase (SDH) and threonine dehydratase (TDH) activities in blood serum was based on the colorimetric measurement of the products, increasing after deamination of 1-serine (pyruvic acid) and 1-threonine (alpha-ketobutyric acid) using the reaction with 2,4-dinitrophenyl hydrazine in an alkaline medium. Conditions for the enzymatic reaction were developed. Activity of enzymes was expressed as micrometer of the reaction products per 1 L of blood serum within 1 hr of incubation at 37 degrees. Blood serum from normal donors did not exhibit the SDH and TDH activities. The enzymatic activity was estimated in 126 patients with various impairments of liver tissue. The procedure developed was shown to be highly sensitive and informative. It enabled to detect both the earliest periods of the cytolytic syndrome and transition of the syndrome into its irreversible step.

L-Threonine deaminase as a possible antitumor agent.

In vitro studies with L-threonine deaminase purified from sheep liver demonstrated that the enzyme was cytotoxic toward two lines of murine leukemia cells but not toward L cells or normal human fibroblasts. When L-threonine deaminase was injected into mice, it was possible to lower the plasma L-threonine concentration by 90%. The enzyme had a half-life of 1.5 hours in the circulation.