Evidence for the synthesis and secretion of APF--a bile lipid associated protein--by isolated rat hepatocytes.

Bile lipids are thought to be secreted in a lipoprotein complex in which they are associated with cholesterol and a protein called the anionic polypeptidic fraction (APF). APF is present in both bile and serum HDL. The association of APF with both bile and lipoprotein strongly suggests that hepatocytes may be responsible for the synthesis and secretion of this protein. In the present work we attempted to verify this by studying the incorporation of [14C]leucine into APF in isolated rat hepatocytes and by immunolocalization in cell cultures. Results obtained showed that synthesis of APF by cells follows the same kinetic pattern as albumin and that it was the third most abundant protein in the bile secretion. Immunolocalization confirmed that APF is synthesized in the endoplasmic reticulum of hepatocytes. This protein which appears to be rapidly secreted could be of great value for the specific detection of the lipids destined for bile secretion.

Bile salt secretion by hepatocytes incubated with bile salts and liposomes or low density lipoproteins.

The purpose of this work was to determine the effect of exogenous unesterified cholesterol provided in either artificial liposomes or LDL on bile salt synthesis by isolated rat hepatocytes. Rates of de novo synthesis were determined in the presence of 300 or 600 microM taurocholate, 600 microM taurodehydrocholate, cholate, deoxycholate or chenodeoxycholate. There was no significant difference between the cholesterol uptake by hepatocytes when the degree of hydrophobicity of the bile salts changed (cholate vs deoxycholate or chenodeoxycholate). Compared to taurocholate, taurodehydrocholate lowered the hepatic incorporation of unesterified cholesterol for the first 60 minutes; compared to control, taurocholate stimulated the cholesterol incorporation for the first 20 minutes. A possible explanation for this finding would be an interaction between bile salts and exogenous cholesterol, depending on the kind of conjugated bile salt. Taurocholate increased the exchange of cholesterol between liposomes or LDL and hepatocyte membranes. It resulted in a significant increase of bile salt synthesis and secretion. This phenomenon was not observed with taurodehydrocholate.

[Pseudohypoxemia and a myeloproliferative syndrome]. / Pseudohypoxémie et syndrome myéloprolifératif.

In the interval between the sampling of blood and analysis of the blood gas composition, the partial pressure of oxygen falls. The rate of fall depends on the temperature, initial level of partial pressure of oxygen in arterial blood, white cell and platelet count. Pseudohypoxaemia secondary to leukaemia and thrombocytosis can be recognized if the arterial blood sample is kept in ice until analysis can be carried out.