Relationship between parameters of lipid peroxidation during obstructive jaundice and after bile flow restoration.

Restoration of bile flow after 9-day cholestasis in rat liver normalized the content of lipid peroxidation products. The removal of the cholestatic factor after 12-day cholestasis was not followed by recovery of these parameters. We showed that measurement of serum concentration of lipid peroxidation products in patients with cholelithiasis during the preoperative period holds promise for selection of the optimum time for surgical treatment and prediction of the risk of postoperative complications.

[Relationship of tumor necrosis factor alpha expression with activation of sphingomyelinase and lipid peroxidation after removal of cholestatic factor].

The goal of this work was to study the expression of tumor necrosis factor alpha (TNFalpha), sphingomyelin cycle activation, and lipid peroxidation (LPO) processes after the removal of a cholestatic factor in the liver subjected to different durations of cholestasis. Restored bile flow after a 9-day hepatic cholestasis normalized sphingomyelinase (SMase) activity and levels of TNFalpha and LPO products. The removal of a cholestatic factor after a 12-day cholestasis did not normalize the studied parameters: SMase activity and the levels of TNFalpha and LPO products remained much higher compared to control. A significant positive correlation between TNFalpha expression, SMase activity, and LPO rate has been revealed. The obtained data indicate that hepatocyte apoptosis after bile outflow restoration in late cholestasis can be due to the activation of the sphingomyelin cycle, LPO, and TNFalpha expression. The synergistic interaction can sharply increase the proapoptotic capacity of each of these factors since TNFalpha activates SMase and LPO, SMase activity depends on the LPO rate, while ceramide, an SMase-produced secondary messenger of apoptosis, can induce oxidative stress.

[Change in the level of endogenous sphingosine in cell nuclei from regenerating rat liver]. / Izmenenie urovnia éndogennogo sfingozina v iadrakh kletok regeneriruiushchei pecheni krys.

High-performance liquid chromatography was used to study the changes in the sphingosine content in regenerating rat liver cell nuclei during RNA and DNA synthesis. It was found that activation of nucleic acid synthesis was accompanied by sphingosine accumulation in cell nuclei in parallel with the induction of the sphingomyelin cycle consisting in the increasing activity of sphingomyelinase and alteration of the sphingomyelin and ceramide content. To clarify the mechanism of sphingosine involvement in replication and transcription, the ability of this product to interact with DNA and modify the activity of RNA-polymerase in vitro was studied. At 10(-4) M sphingosine prevented the interaction of acridine orange with DNA and activated the transcription enzymes. Several alternative mechanisms of sphingosine involvement in the control of nucleic acid synthesis are discussed.

[Effect of sphingomyelin on RNA-polymerase activity in the cell nucleus of normal and regenerating rat liver]. / Vliianie sfingomielina na aktivnost' RNK-polimeraz v iadrakh kletok normal'noi i regeneriruiushchei pecheni krys.

Using a model of regenerating rat liver, it was shown that the activities of RNA polymerases I and II, and the ratio of free to template engaged form of the enzyme are correlated with the changes in the contents of sphingomyelin in chromatin isolated from cell nuclei of hepatectomized animals. Injections of sphingomyelin to intact and hepatectomized animals in doses increasing its contents in chromatin, stimulate the activity of RNA polymerases I and II and increase the ratio of free to engaged form of the enzyme. Addition of sphingomyelin as a micellar suspension to heterochromatin in vitro facilitates RNA polymerase binding to the template. Removal of sphingomyelin from the intranuclear structures by its degradation with sphingomyelinase results in a loss of activities of both RNA polymerases. It is assumed that sphingomyelin plays a role in the transcriptional activity by changing the structure of the template and that of the enzymes.