Chronic ethanol administration depresses fatty acid synthesis in rat adipose tissue.

Administration of ethanol as part of a nutritionally adequate liquid diet to female Wistar rats was found to depress markedly incorporation of labelled glucose into adipose-tissue acylglycerol fatty acids. Similar results with labelled pyruvate and acetate suggested inhibition of the fatty-acid-synthesis pathway at, or distal to, the acetyl-CoA carboxylase step. Activities of acetyl-CoA carboxylase and fatty acid synthetase were markedly lower in ethanol-fed animals. The activity of another lipogenic enzyme, phosphatidate phosphohydrolase, was not affected by chronic ethanol feeding. These findings suggest that chronic ethanol administration has marked effects on adipose-tissue lipogenesis.

The incorporation of [myo-2-3H] inositol into phosphatidyl inositol of stimulated rat pancreas.

The 'phospholipid effect' involves agonist induced breakdown of phosphatidyl inositol (PI) or its phosphorylated derivates with increased incorporation of 32P or [myo-2-3H] inositol during resynthesis. In rat pancreas pancreozymin and bethanecol resulted in the standard dose dependent increased incorporation of 32P into PI which was paralleled by increased amylase secretion. By contrast the incorporation of [myo-2-3H] inositol into PI was significantly decreased by pancreozymin whereas bethanecol had no effect. However, pancreozymin caused a 30% decrease in labelled PI irrespective of whether it was prelabelled with 32P or [myo-2-3H] inositol. Thus in rat pancreas, pancreozymin resulted in the standard agonist induced breakdown of pre-labelled PI but inhibited the incorporation [2-3H-myo] inositol during the resynthetic phase.

Chronic ethanol feeding causes accumulation of serum cholesterol in rat pancreas.

In a previous study, a rat model of ethanol-induced pancreatic steatosis was developed in which chronic ethanol feeding resulted in a twofold increase in pancreatic cholesteryl ester content. The studies reported here were performed in order to elucidate the mechanism of this cholesteryl ester accumulation. Rats were pair fed ethanol or control diets for 3 weeks. Ethanol feeding resulted in an increased accumulation of serum cholesterol in the pancreas. Ethanol feeding also resulted in increased in vitro incorporation of labeled acetate and mevalonate into the sterol moiety of pancreatic cholesteryl ester and increased incorporation of labeled acetate into its fatty acid component. These results suggest that chronic ethanol feeding causes pancreatic cholesteryl ester accumulation by affecting exchange of cholesterol between serum and pancreatic tissue.

Increased phospholipid synthesis in the stimulated rat and human pancreas.

Stimulation of the exocrine pancreas is associated with marked changes in pancreatic phospholipid metabolism. It has been previously established that de novo synthesis of phospholipids constitutes part of this "phospholipid effect". This study has demonstrated that in vitro stimulation of the rat pancreas utilising bethanecol and pancreozymin results in increased incorporation of labelled glucose into phosphatidyl inositol and, to a lesser extent, other phospholipids, suggesting increased de novo synthesis of these compounds. However, secretin which is believed to act via a different intracellular pathway, did not exert such an effect. The relevance of this animal model is indicated by the demonstration of increased incorporation of labelled glucose into phospholipids of human pancreas stimulated in vitro by bethanecol or sincalide (the active carboxy terminal octapeptide of pancreozymin).

Alcohol causes a fatty pancreas. A rat model of ethanol-induced pancreatic steatosis.

To develop an animal mode of alcoholic pancreatic steatosis, female Wistar rats were pair fed liquid diets, containing ethanol as 36% of calories or an isocaloric amount of carbohydrate for 3 weeks. Electron microscopic examination showed lipid vesicles localized principally at the bases of pancreatic acinar cells in the ethanol-fed rats. Ethanol feeding significantly increased pancreatic content of cholesteryl ester without changing levels of other lipids. Ethanol feeding enhanced labeled acetate, palmitate, oleate, and linoleate incorporation into cholesteryl ester. Therefore, increased esterification of cholesterol may, in part, explain the observed accumulation of cholesteryl ester.

Lipoprotein lipids in renal transplant recipients of different pre-transplant etiology of renal disease. A comparison of male and female patients.

Serum and lipoprotein lipids have been compared in male and female transplant recipients with glomerulonephritis or analgesic nephropathy as etiology of pre-transplant renal disease, and a number of differences were observed. (1) Serum cholesterol and phospholipid levels were elevated in glomerulonephritis and female analgesic nephropathy, but not in male analgesic nephropathy patients. (2) Glomerulonephritis patients had normal low density lipoprotein (LDL) cholesterol levels whereas these were elevated in female and depressed in male analgesic nephropathy patients. (3) LDL phospholipid, on the other hand, was normal in male and elevated in female transplant recipients irrespective of etiology of pre-transplant renal disease, while high density lipoprotein (HDL) phospholipid levels were elevated in female glomerulonephritis patients only. Mild hypertriglyceridemia and a tendency to increased HDL cholesterol were observed in all patients. These results provide further evidence for the complexity of lipoprotein lipid abnormalities in renal disease.

Ethanol-induced changes in cardiac lipid metabolism.

The influence of ethanol on cardiac lipid metabolism has been investigated in the rat. Acute in vitro ethanol significantly stimulated the incorporation of 14C-1-acetate but not 14C-U-glucose into cardiac lipid in rats fed a diet free of ethanol for 3 weeks. Stimulation of incorporation was not uniform but was confined to the diglyceride and triglyceride fractions. This response of cardiac tissue lipid metabolism to acute ethanol was not observed in rats pair fed an isocaloric diet containing 36% of calories as ethanol. Chronic ethanol feeding significantly increased cardiac triglyceride content when compared with pair-fed controls. It also stimulated oxidation of labeled palmitate, but did not affect in vitro lipogenesis.

Influence of ethanol on pancreatic lipid metabolism.

The influence of acute exposure to ethanol on rat pancreatic lipogenesis has been investigated. Marked alterations of in vitro pancreatic lipid metabolism were found with changes compatible with increased de novo triglyceride synthesis. Ethanol in vitro stimulated (U--14C) glucose incorporation into triglyceride, but inhibited incorporation into phosphatidyl choline. Prior exposure to ethanol did not further enhance these effects on labeled glucose incorporation. One hour after feeding ethanol at a dose of 378 mg/100 g body weight, (1--14C) acetate incorporation in vitro into pancreatic lipid was significantly increased. This increase was not uniform, but was confined to the free fatty acid, triglyceride, sphingomyelin, and phosphatidyl choline fractions. Similar observations were made when pancreatic tissue from saline-fed control animals was incubated in the presence of ethanol at a concentration of 3.4 mM. Prior exposure to ethanol enhanced this stimulatory effect, and tissue from the alcohol-fed animals incubated in the presence of ethanol incorporated more acetate label into all lipid fractions than tissue from alcohol-fed animals incubated without ethanol and from saline-fed animals incubated in the presence of ethanol.

The influence of pre-transplant etiology of renal disease on lipoprotein lipids in female renal allograft receipients.

Serum and lipoprotein lipids were determined in 42 female transplant recipients and compared with age-matched and serum lipid-matched normal subjects. Eight patients had glomerulonephritis as the pre-transplant etiology of renal disease, 22 had analgesic nephropathy, 6 polycystic kidneys and 6 ureteric reflux. A number of abnormalities were observed: (i) Serum triglycerides and phospholipids were elevated in all patients. Serum cholesterol levels were increased in analgesic nephropathy, polycystic kidney and ureteric reflux, but not in glomerulonephritis patients. The serum esterified/free cholesterol ratio was reduced in all patients except those with polycystic kidneys as the pre-transplant diagnosis; (ii) All VLDL lipids were raised in transplant patients regardless of etiology of renal disease prior to transplantation; (iii) LDL lipids, cholesterol, triglyceride and phospholipid were elevated in analgesic nephropathy, polycystic kidney and ureteric reflux patients, but were normal in glomerulonephritis patients: (iv) HDL cholesterol and triglycerides were elevated in all patients regardless of etiology. HDL phospholipid levels also tended to be raised, but this was significant only in glomerulonephritis patients. Lipoprotein--lipid ratio data indicated that lipoprotein--lipid composition deviated less from normal in glomerulonephritis patients than in the other patient groups.

Lipoprotein lipids in chronic renal failure and haemodialysis. The influence of etiology and implications for atherogenesis.

Lipoprotein lipid analysis has been carried out in 39 women and 28 men with chronic renal failure on haemodialysis. The results have been analysed in relation to the etiology of the renal disease and compared with those obtained in age- and sex-matched controls and in triglyceride-matched controls. Serum cholesterol was normal or low in glomerulonephritis but was normal in analgesic nephropathy. Serum triglycerides and VLDL lipids were raised uniformly regardless of the etiology of the renal disease. LDL triglyceride and HDL triglyceride were also raised. LDL cholesterol and phospholipid were low in glomerulonephritis but were normal in analgesic nephropathy. HDL cholesterol was reduced in both male and female patients regardless of etiology, statistical significance was not reached for the women. The ratio of esterified to free cholesterol tended to be reduced in all the lipoproteins regardless of sex or etiology but the changes were not significant in all groups. Comparison of the lipid abnormalities with those found in other hyperlipidaemic states suggests that the lipid disorders found in chronic renal failure are probably insufficient to explain the rapid development of vascular disease which has been reported.

Combined hyperlipidemia and hypertriglyceridemia in renal allograft recipients. Comparison with non-renal combined hyperlipidemic or hypertriglyceridemic patients and normal subjects.

In order to investigate the degree of similarity between renal transplant and non-renal combined hyperlipidemic and hypertriglyceridemic patients, serum and lipoprotein lipid compositions were compared in transplant and non-renal combined hyperlipidemic and in transplant and non-renal hypertriglyceridemic patients, and normal subjects. Although certain similarities were demonstrated, combined hyperlipidemia in transplants differed from that in non-renal patients in a number of respects: (1) LDL-triglyceride levels were increased to a greater extent in transplant than in non-renal patients in females, while LDL-phospholipid was elevated in male transplants only; (2) HDL-cholesterol levels were raised in transplants relative to non-renal patients in females, and relative to both non-renal patients and normal subjects in males; (3) a number of differences in lipoprotein-lipid ratios between transplant and non-renal patients were demonstrated for all three lipoprotein fractions. In hypertriglyceridemia, changes in lipoprotein-lipid levels were similar in transplant and non-renal patients with the exception of HDL-cholesterol levels, which were decreased in non-renal patients only. Furthermore, the ratio of esterified to free cholesterol in LDL and HDL was decreased in non-renal but not in transplant patients. The data presented demonstrate that, despite certain similarities, a number of the lipoprotein-lipid changes observed in transplant combined hyperlipidemia and in transplant hypertriglyceridemia differ from those observed in non-renal patients with similarly elevated serum lipids.

Hypercholesterolemia in renal allograft recipients. Comparison with non-renal hypercholesterolemia and normal subjects.

In order to investigate the degree of similarity between renal transplant and non-renal hypercholesterolemia, serum and lipoprotein lipid compositions were compared in female transplant hypercholesterolemic patients (serum cholesterol greater than 240 mg/100 ml, serum triglyceride less than 150 mg/100 ml) and female non-renal hypercholesterolemic and normal subjects. A number of lipid abnormalities were demonstrated: (1) Serum and LDL cholesterol and phospholipid levels were significantly elevated in both transplant and non-renal hypercholesterolemic patients; (2) Serum triglyceride, VLDL choelsterol, triglyceride and phospholipid, and LDL and HDL triglyceride were significantly increased in transplant hypercholesterolemic patients. Changes of this nature are usually found in hypertriglyceridemia, and were not observed in non-renal hypercholesterolemic subjects. Finally, a number of changes in the ratio of esterified to free cholesterol and in the ratios of other lipoprotein-lipids, most of which did not correspond to any changes found in the common non-renal hyperlipidemias, were also demonstrated.

Serum lipoprotein abnormalities in renal allograft recipients.

Detailed lipid composition of serum and isolated lipoprotein fractions in male and female transplant recipients has been determined. Results have been compared with appropriate controls and a number of abnormalities have become apparent: (i) Serum total cholesterol, triglyceride and phospholipid levels were significantly elevated in transplant recipients. (ii) All lipid classes VLDL were significantly increased in both male and female patients. (iii) LDL-total cholesterol, triglyceride and phospholipid were significantly raised in female transplant patients, but this was true only for LDL-triglyceride in male patients. (iv) In female patients, HDL-total cholesterol and -triglyceride were significantly elevated, while in male patients, HDL-total cholesterol, but not HDL-triglyceride, was significantly greater than in controls. (v) The ratio of esterified to free cholesterol was significantly reduced in HDL of female transplant recipients. Results from correlation analysis suggest a relationship between some of the lipid abnormalities and renal function in female patients, while in male patients only immunosuppressive therapy is implicated.

Endothelial cell morphology in areas of in vivo Evans blue uptake in the aorta of young pigs. II. Ultrastructure of the intima in areas of differing permeability to proteins.

The fine structure of the intima of the pig aortic arch is described for areas of spontaneously differing in vivo endothelial permeability, as demarcated by uptake of the protein-binding azo dye Evans blue. Areas of enhanced permeability (blue areas) consistently show a variety of features not observed in areas devoid of dye accumulation (white areas). The subendothelial space of blue areas is markedly thickened and edematous, containing collagen, elastic tissue elements, and undifferentiated cells dispersed in an amorphous floccular matrix of low electron density. Endothelial cells in blue areas are generally cuboidal, with relatively short, frequently vacuolated junctions. In contrast, endothelial cells from white areas are flat and elongate, with long intercellular junctions exhibiting many interdigitations. Cytoplasmic differences include a well-developed rough endoplasmic reticulum and more frequent lysosomal bodies in blue areas and a prominent Golgi apparatus in the endothelium of white areas. Additionally, endothelial cell injury or death with and without denudation occurs with a significantly greater frequency in blue relative to white areas. An endothelial glycocalyx is some threefold thicker over the surface of white relative to blue areas. It is concluded that neither endothelial structure nor function are homogeneous within the aortic arch of the young pig and that areas of spontaneously differing permeability to proteins are associated with a spectrum of alterations in endothelial and intimal morphology.

Some aspects of aortic medial explant morphology and lipid metabolism.

This study has examined some aspects of lipogenesis in both primary aortic medial explant cultures and intact aortic intima-media preparations. It has been shown that both lipogenesis and cellular ultrastructure vary with the age of the culture. Additionally, data has been presented indicating marked qualitative and quantitative differences in lipogenesis between explant cultures and intima-media incubations. Finally, it has been shown that the addition of either normo- or hyperlipemic human serum to explant cultures can significantly modify acetate incorporation into both triglycerides and cholesteryl esters and induce significant changes in ultrastructural morphology. it is concluded that one should interpret cell culture data with caution, particularly with respect to culture age, serum composition, and ultrastructural cellular viability.