Effect of intravenous polyunsaturated phosphatidylcholine infusion on insulin receptor processing and lipid composition of erythrocytes in patients with liver cirrhosis

Activity of essential phospholipids (EPL) from soybean in liver diseases

Essential phospholipids (EPL) contain a highly purified extract of polyenylphosphatidylcholine (PPC) molecules from soybean. The main active ingredient is 1,2-dilinoleoylphosphatidylcholine (DLPC), which differentiates it from other phospholipids, lecithins, or extracts from other sources. Although EPLis widely used in liver diseases of various origins, its mode of action and pharmacological and clinical evidence of its efficacy have not yet been concisely reviewed. This paper critically summarizes experimental and clinical results. With regard to in-vitro and animal tests, EPL influenced membrane-dependent cellular functions and showed anti-oxidant, anti-inflammatory, anti-fibrotic, apoptosis-modulating, regenerative, membrane-repairing and -protective, cell-signaling and receptor-influencing, as well as lipid-regulating effects in intoxication models with chemicals or drugs. Clinical studies, primarily from European and Asian countries, have shown improvement in subjective symptoms; clinical, biochemical and imaging findings; and histology in liver indications such as fatty liver of different origin, drug hepatotoxicity, and adjuvant in chronic viral hepatitis and hepatic coma. The available studies characterize EPL as evidence-based medicine, although further long-term controlled clinical trials are required to precisely determine its benefit for alleviating symptoms, improving well-being, inducing histological changes and slowing the progression of liver disease. EPL-related relevant side effects were not observed.

Cytoprotective effects of polyenoylphosphatidylcholine (PPC) on beta-cells during diabetic induction by streptozotocin

Polyenoylphosphatidylcholine (PPC), a phosphatidylcholine-rich phospholipid extracted from soybean, has been reported to protect liver cells from alloxan-induced cytotoxicity. The present study aimed to investigate whether PPC protects pancreatic beta-cells from the cytotoxic injury induced by streptozotocin, thus preserving insulin synthesis and secretion. beta-Cells of the PPC-treated rats showed a significant reduction of cell death with lesser destruction of plasma membrane on streptozotocin insult. They demonstrated a rapid recovery of GLUT-2 expression, whereas almost irreversible depletion of membrane-bound GLUT-2 was seen in beta-cells of the rats treated with only streptozotocin. A similar cytoprotective effect of PPC was also monitored in the PPC-pretreated MIN6 cells. These beta-cells retained their ability to synthesize and secrete insulin and no alteration of glucose metabolism was detected. These results strongly suggest that PPC plays important roles not only in protecting beta-cells against cytotoxicity but also in maintaining their insulin synthesis and secretion for normal glucose homeostasis.

Polyunsaturated fatty acid deficiency in liver diseases: pathophysiological and clinical significance

Polyunsaturated fatty acid (PUFA) deficiency occurs in advanced cirrhosis and other liver diseases (acute hepatitis, cholestasis). Long-chain PUFA deficit in cirrhosis is due to both essential fatty-acid (EFA) deficiency and impaired PUFA biosynthesis. Although hepatic insufficiency itself mostly accounts for this phenomenon, other factors such as associated malnutrition also play a role. PUFA deficiency in cirrhosis probably has a wide array of both cellular and clinical consequences, but, at present, they have been difficult to prove. In addition, the route, dosage, and safety of PUFA supplementation in these patients needs extensive investigation in the future.

Liver alcoholic cirrhosis and spur-cell (acanthocytic) anaemia. A study of erythrocyte ghost composition and fluidity

BACKGROUND

The occurrence of spur-cell anaemia in the course of cirrhosis is rare. Alterations of the lipid composition and fluidity of erythrocyte (RBC) ghosts may be present and participate in the phenomenon.

METHODS

A 59-year-old male patient with alcoholic cirrhosis developed severe spur-cell haemolytic anaemia before death. We compared his RBC ghosts with those of 10 cirrhotic patients and used a group of 9 healthy subjects as controls.

RESULTS

The cholesterol to protein ratio was higher in cirrhotic patients; besides, they had less unsaturated fatty acid. The ratio of phospholipid phosphorus to protein did not change; yet, the distribution of phosphorus among phospholipid classes was altered. No difference in 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy (membrane fluidity) was observed between the ghosts of cirrhotic patients and those of healthy people. However, the ghosts of the patient with spur-cell anaemia were more rigid than those of either group.

CONCLUSIONS

The values of most variables of cirrhotic patients' ghosts lay between those of healthy subjects and those of the one who developed spur-cell anaemia. It is concluded that some homeostatic mechanisms must control fluidity during cirrhosis; in some cases alterations are particularly great, and fluidity cannot be maintained.

Insulin Receptor Processing and Lipid Composition of Erythrocyte Membrane in Patients with Hyperlipidemia

The aim of this study was to determine whether the common forms of dyslipidemia could affect either the lipid composition or insulin receptor processing (down-regulation) of erythrocytes. The study included 22 patients with type IIa hypercholesterolemia, 15 patients with type IV hypertriglyceridemia and 12 patients with type IIb hyperlipidemia. Ten normolipidemic subjects were used as controls. Their erythrocyte membranes were analyzed for lipid composition and insulin receptor down-regulation. The results show that all the hyperlipidemias investigated were characterized by significant increases in the cholesterol to phospholipid molar ratio (0.56 +/- 0.08 in controls and 1.11 +/- 0.13, 1.09 +/- 0.14, 1.04 +/- 0.15, p < 0.001, in types IIa, IIb and IV, respectively). Surface insulin receptors of type IIa and IIb patients did not appear to down-regulate when compared to normal subjects, but rather up-regulated (+65.2% in controls, -1.0% and -8.7%, p < 0.001, in type IIa and IIb patients, respectively). Patients with type IV hypertriglyceridemia showed a residual capacity for insulin receptor internalization (10.7% down-regulation). Membranes of all the patients contained a higher proportion of phosphatidylethanolamine; the molar ratio of sphingomyelin to phosphatidylcholine was significantly higher in types IIb than in controls (1.22 +/- 0.11 and 1.12 +/- 0.10, p < 0.05, respectively); all the patients showed a lower content of polyunsaturated fatty acids in the major glycerophospholipid classes. However, type IV hypertriglyceridemics showed less variations, especially in the phosphatidylserine fraction. These results indicate that the alterations in lipoprotein pattern may affect both the lipid membrane equilibria and the processing ability of surface insulin receptors. Copyright 1995 S. Karger AG, Basel

Age-related variations in plasma and liver lipids of Yoshida rats: a comparison with Wistar rats

Lipoprotein and liver lipids of spontaneously hyperlipidemic Yoshida rats were compared with those of normolipidemic Wistar animals for studying their age- and strain-related differences. Both strains showed an age-related increase in the total plasma cholesterol concentration. However, the Yoshida strain had a higher content of cholesteryl esters and triglycerides than the Wistar strain in both young and adult animals (2- and 8-month-old animals, respectively). The free cholesterol content was also higher, but only in the 8-month-old animals. Both strains showed an age-related increase in the proportion of HDL1 and a symmetrical decrease in both the HDL2 and HDL3 subfractions, but the variations were more evident in the Yoshida strain. The study of strain-related differences suggested that the spontaneous hypertriglyceridemia of the Yoshida strain was not only related to the higher amount and proportion of the VLDL fraction, but also to the higher content of triglycerides in the LDL fraction. The livers of Yoshida rats accumulated more triglycerides (with an age-related progression) than those of Wistar rats. The major lipid classes in the liver of Yoshida rats contained a significantly higher proportion of monounsaturated fatty acyls. Furthermore, this proportion showed an age-related increase in all the lipid classes, but in cholesteryl esters. This suggested that liver desaturases had a relevant role in the development of hyperlipidemia, and of its age-related variations, in the Yoshida strain.(ABSTRACT TRUNCATED AT 250 WORDS)