Artificial Lipid Emulsion Research Articles

Effects of anabolic androgenic steroids on chylomicron metabolism

ObjectiveTo evaluate the effects of anabolic androgenic steroids (AAS) on chylomicron metabolism. MethodsAn artificial lipid emulsion labeled with radioactive cholesteryl ester (CE) and triglycerides (TG) mimicking chylomicrons was intravenously injected into individuals who regularly weight trained and made regular use of AAS (WT+AAS group), normolipidemic sedentary individuals (SDT group) and individuals who also regularly weight trained but did not use AAS (WT group). Fractional clearance rates (FCR) were determined by compartmental analysis for emulsion plasma decay curves. ResultsFCR-CE for the WT+AAS group was reduced (0.0073±0.0079min−1, 0.0155±0.0100min−1, 0.0149±0.0160min−1, respectively; p<0.05), FCR-TG was similar for both the WT and SDT groups. HDL-C plasma concentrations were lower in the WT+AAS group when compared to the WT and SDT groups (22±13; 41±7; 38±13mg/dL, respectively; p<0.001). Hepatic triglyceride lipase activity was greater in the WT+AAS group when compared to the WT and SDT groups (7243±1822; 3898±1232; 2058±749, respectively; p<0.001). However, no difference was observed for lipoprotein lipase activity. ConclusionsData strongly suggest that AAS may reduce the removal from the plasma of chylomicron remnants, which are known atherogenic factors.

Ausência de efeito do captopril no metabolismo de uma emulsão lipídica artificial semelhante aos quilomícrons em pacientes hipertensos e hipercolesterolêmicos

To assess the effect of captopril, an angiotensin-converting enzyme inhibitor, on the metabolism of chylomicrons and their remnants and the possible alterations in the concentrations of plasma lipids caused by the drug in hypertensive hypercholesterolemic individuals. The metabolism of chylomicrons was tested with the method of artificial lipid emulsion of chylomicrons labeled with 3H-cholesteryl oleate. The emulsion was injected intravenously in 10 patients with mild-moderate arterial hypertension before and 45 days after treatment with captopril (50 mg/day). After injection, blood samples were collected during 60 minutes at pre-established time intervals for determining the decay curve, the fractional catabolic rate (FCR in min-1), and the plasma residence time of the artificial lipid emulsion by analyzing different compartments. The plasma concentrations of the lipids were also assessed before and after treatment. The fractional catabolic rate (min-1) of the lipid emulsion before and after treatment with captopril (0.012 +/- 0.003 and 0.011 +/- 0.003, respectively; p = 0.85, n.s.) and the plasma residence time of the emulsion (83.3 +/- 20.8 and 90.9 +/- 22.5 min, n.s.) did not change, but the total cholesterol and LDL-C levels decreased by 7% and 10%, respectively (p = 0.02). The concentrations of HDL-C, triglycerides, Lp(a), and apolipoproteins AI and B did not change. Treatment with captopril, evaluated with the artificial lipid emulsion method, does not cause deleterious changes in the metabolism of chylomicrons and their remnants.

Peroxidation of Artificial Lipid Emulsions During Infusion

Peroxidation of Artificial Lipid Emulsions During Infusion

エマルション表面膜構造に依存するリポ蛋白質リパーゼ酵素反応

The hydrolysis of triglycerides (TG) by lipoprotein lipase (LPL) is a crucial process in the metabolism of TG-rich lipoproteins and artificial lipid emulsions injected intravenously. In this study, we found that sphingomyelin (SM) at the emulsion surface inhibits LPL-mediated lipolysis both in vivo and in vitro. Incorporation of SM into the emulsion surface caused an increase in the apparent Michaelis-Menten constant (Km (app)) and a decrease in the apparent maximal lipolysis rate (Vmax (app)). SM was also found to affect factors which may be related to the kinetic parameters; that is, SM increased TG solubility in surface layers and decreased apoC-II binding to the emulsion surface. Interestingly, cholesterol (Chol) did not affect the lipolysis rates although it decreased TG solubility and apoC-II binding. These results indicated that neither TG solubility at the surface layer nor amount of apoC-II binding are determining factors in LPL-mediated lipolysis under physiological conditions. Furthermore, on the basis of kinetic studies, we showed that SM inhibits lipolysis by decreasing both the binding affinity for emulsions and the catalytic activity of LPL.The mechanism by which SM at the emulsion surface inhibits lipolysis was also discussed. SM strongly increased head group packing probably due to the high capacity of forming hydrogen bonds, whereas Chol had little effect on the head group structure of the emulsion surface. Decreasing the head group mobility by SM could inhibit the insertion of the binding region of LPL protein, resulting in increases in Km (app). In addition, SM stabilizes TG in the surface layer and retards the transfer of TG from the lipid particle surface to the catalytic pocket of LPL, resulting in decreases in LPL catalytic activity and Vmax (app). Our results suggested that head group packing significantly affects LPL binding to the lipid surface and that TG stability in the surface layer is important for the LPL catalytic activity.From these results, the content of SM in the lipoprotein surface is presumed to play an important role in controlling LPL-mediated lipolysis by the mechanism described above. Artificial lipid emulsions are used as drug carriers, and the control of TG hydrolysis of lipid carriers is important for development of better drug delivery systems. The lipolysis activity can be modulated by surface lipid properties, i.e., the surface lipid composition.

Simultaneous measurements of chylomicron lipolysis and remnant removal using a doubly labeled artificial lipid emulsion: studies in normolipidemic and hyperlipidemic subjects.

An artificial chylomicron-like lipid emulsion doubly labeled with tri[(N)3H]oleoylglycerol ([3H]TO) and cholesteryl [1-14C]oleate ([14C]CO) was infused intravenously into human subjects with the purpose of simultaneously measuring the plasma disappearance rates (residence time, RT) of [14C]CO, which represents solely the splanchnic organ uptake of the remnant chylomicron core, and of [3H]TO, which combines the remnant disappearance with the shedding off of chylomicron triglycerides by the action of lipoprotein lipase. Thus, the fraction of the particle triglyceride content that is removed before the remnant is taken up is expressed as a delipidation index (DI = 1 - RT of [3H]TO/RT of [14C]CO. The present procedure has an advantage over the use of chylomicrons labeled with retinyl ester or radioactive triglycerides alone that represent, respectively, the chylomicron remnant or the whole particle metabolism only. When normal subjects as well as primary hyperlipidemic subjects were studied, the plasma triglyceride concentration was directly related to [14C]CO RT and [3H]TO RT, but inversely related to the delipidation index. There may be different patterns of relations between these parameters of chylomicron metabolism in primary and in secondary hyperlipidemias, as well as under the action of drugs that influence the metabolism of lipoproteins.

Abnormal activation of lipoprotein lipase by non-equilibrating apoC-II: further evidence for the presence of non-equilibrating pools of apolipoproteins C-II and C-III in plasma lipoproteins

Using artificial triglyceride emulsions, we have demonstrated the presence of non-equilibrating pools of apolipoproteins C-II and C-III in human plasma lipoproteins. As the concentrations of acceptor triglycerides were increased, a greater fraction of both apoC-II and apoC-III shifted away from the native plasma lipoproteins to the artificial lipid emulsions. All of the apoC-II and apoC-III in very low density and high density lipoproteins (VLDL and HDL), however, could not be removed from native plasma lipoproteins. The percent of total plasma apoC-II and apoC-III that could be recovered in the VLDL and HDL density fractions varied when plasma from different individuals was used. When plasma samples from normotriglyceridemic subjects were used, HDL was the primary donor of apoCs. The percent of total plasma apoCs associated with HDL decreased from 60% to 25% for apoC-II and from 65% to 15% for apoC-III. When plasma samples from hypertriglyceridemic subjects were incubated with artificial lipid emulsions, VLDL was the primary donor of apoCs. HDL from hypertriglyceridemic subjects only accounted for 5-10% of total fasting plasma apoCs and did not contribute significantly to the final apoC contents of the artificial triglyceride emulsions. To evaluate the significance of the depletion of exchangeable apoCs from plasma HDL, we also examined the ability of control and apoC-depleted HDL to serve as activator for bovine milk lipoprotein lipase (LPL) in vitro. When HDL depleted of exchangeable apoCs were used as the source of plasma apolipoproteins for the activation of LPL in vitro, only 5-10% of the maximal activity obtained with native HDL was demonstrated. In fact, in the presence of comparable concentrations of HDL apoC-II, activation of LPL was the least with HDL which lacked exchangeable apoCs. Our data thus indicated that the presence of exchangeable apoC-II on HDL is necessary for the activation of LPL in vitro. This finding is consistent with our data that suggest that HDL from hypertriglyceridemic subjects do not stimulate LPL as well as HDL from normolipidemic subjects.

Infusion of atherogenic lipoprotein particles increases hepatic lipase activity in the rabbit.

Hepatic lipase plays a key role in the turnover of potentially atherogenic lipoprotein remnants and in determining the relative distribution of high density lipoprotein (HDL) particle size subclasses. Rabbits fed a cholesterol-enriched diet have been found to accumulate potentially atherogenic chylomicron remnants and beta-very low density lipoprotein (beta-VLDL) and show a rapid increase in liver and postheparin plasma hepatic lipase activity. To determine whether the particles that accumulate during cholesterol feeding are a stimulus for this increase in hepatic lipase activity, we infused normal chow-fed rabbits with a chylomicron remnant plus beta-VLDL-enriched plasma fraction isolated from rabbits fed 0.5% cholesterol-supplemented chow. The infusion of this plasma fraction for 4 h increased hepatic lipase activity up to 2.9-fold over control rabbits and resulted in a loss of larger sized HDL particles consistent with the action of hepatic lipase. The increase in activity was significantly correlated with the concentration of infusate phospholipid, unesterified cholesterol, and esterified cholesterol, but not with the infusate triglyceride concentration. The change in the plasma cholesterol concentration of recipient rabbits, which reflects the degree of lipoprotein accumulation in these rabbits, was also significantly correlated with the change in hepatic lipase activity. However, a chylomicron remnant and beta-VLDL-depleted fraction of plasma from cholesterol-fed rabbits did not increase hepatic lipase activity. Furthermore, triglyceride presented as an artificial lipid emulsion (Intralipid) was not able to stimulate hepatic lipase activity, although triglyceride is a substrate for hepatic lipase.(ABSTRACT TRUNCATED AT 250 WORDS)

Pig apolipoprotein R: a new member of the short consensus repeat family of proteins.

Apolipoprotein R (apoR) is a 23-kDa protein found on very low-density lipoprotein (VLDL), on chylomicrons, and in the d > 1.21 g/mL fraction of pig plasma. The plasma concentration of apoR is 5.1 micrograms/mL, with 11.5% of apoR found on VLDL. In vitro, apoR can transfer from the d > 1.21 g/mL infranatant onto artificial lipid emulsions or human chylomicrons but not onto human VLDL. An apoR cDNA was isolated from a pig liver lambda gt11 expression library. DNA sequence analysis of the apoR cDNA revealed 67% identity with the 3'-terminal region of human C4b-binding protein alpha-chain cDNA (C4BP alpha). C4BP alpha is a 70-kDa glycoprotein that regulates both the coagulation and the complement cascades. In plasma, C4BP alpha exists as disulfide-linked multimers consisting of seven C4BP alpha chains and a single C4BP beta chain. Like C4BP, apoR forms high molecular weight disulfide-linked complexes in plasma. However, unlike C4BP alpha, apoR complexes do not appear to contain C4BP beta. ApoR mRNA was detected in pig liver, spleen, lung, bone marrow, and lymph node, but was absent in intestine and white blood cells. This distribution is consistent with the production of apoR in terminally differentiated macrophages but not in blood monocytes. ApoR mRNA was not detected in RNA isolated from human liver or lung. ApoR may be a lipoprotein-borne regulator of either the coagulation or the complement cascades.

Inhibition of adhesion of S-fimbriated Escherichia coli to buccal epithelial cells by human milk fat globule membrane components: a novel aspect of the protective function of mucins in the nonimmunoglobulin fraction.

We investigated the presence of factors in human milk that inhibit invasion of pathogenic bacteria. The effect of human milk fat globule membrane (HMFGM) components on adhesion of cloned S-fimbriated Escherichia coli to human buccal epithelial cells was analyzed. S fimbriae are a common feature of E. coli strains causing sepsis and meningitis in newborns and are bound to epithelia via sialyl-(alpha-2-3)galactoside structures. Human milk fat globules (HMFG) could be agglutinated by the above-mentioned bacteria. Agglutination could be inhibited by fetuin, human glycophorin, and alpha 1-acid glycoprotein. In addition, pretreatment of HMFG with Vibrio cholerae neuraminidase markedly reduced bacterium-induced agglutinations, indicating the involvement of neuraminic acid-containing glycoproteins. In contrast, lipid droplets of infant formula or artificial lipid emulsions (Intralipid) could not be agglutinated. HMFG were present in stools of breast-fed neonates as shown by indirect immunofluorescence staining with a monoclonal antibody directed against carbohydrate residues present on HMFGM. These HMFG could be agglutinated by bacteria. HMFG inhibited E. coli adhesion to buccal epithelial cells. To further characterize relevant E. coli binding structures, HMFGM components were separated by gel chromatography. The mucin fraction showed the most pronounced inhibitory effect on adhesion of S-fimbriated E. coli to human buccal epithelial cells. Our data suggest that HMFG inhibit bacterial adhesion in the entire intestine and thereby may provide protection against bacterial infection.

Milk lipid digestion in the neonatal dog: the combined actions of gastric and bile salt stimulated lipases

Intragastric lipolysis may be particularly important for the digestion of milk lipid since milk fat globules are resistant to pancreatic lipase without prior disruption; milk bile salt stimulated lipase (BSSL) may supplement further intestinal hydrolysis. Previous information on gastric lipolysis has been based primarily on in vitro studies using artificial lipid emulsions containing a single component fatty acid and have focused on the preferential release of medium-chain fatty acids. The actual contribution of these enzymes to overall fat digestion in vivo on natural substrates has rarely been studied, however. The neonatal dog is an excellent model in the study of lipid digestion because, like the human, milk lipids are high in long-chain unsaturated fatty acids, milk contains BSSL and gastric lipase is the predominant lipolytic enzyme acting in the stomach. We used a combination of in vivo studies with in vitro incubations to investigate digestion of milk lipid by gastric and milk (BSSL) lipases in the suckling dog. In the first 4 weeks postpartum, 14–41% and 42–60% of milk triacylglycerol was hydrolyzed to primarily diacylglycerol and free fatty acid (FFA) in the first 30 and 60 min in the stomach, respectively. Milk lipid contained high levels (63%) of long-chain unsaturated fatty acids, which were preferentially released as FFA during in vivo gastric lipolysis, consistent with the actions and stereospecificity of gastric lipase. While levels of hydrolysis in gastric aspirates were significantly different (by age and time in stomach) at the start of in vitro studies, total hydrolysis in all incubation systems plateaued at about 65%, suggesting product inhibition by the long-chain FFA, but to a much lesser degree than previously expected from in vitro studied. The magnitude of in vivo intragastric lipolysis was 3- to 6-times greater than that predicted by in vitro assays using either milk lipid or labeled emulsion as substrate, respectively. Prior exposure to intragastric lipolysis resulted in 30% hydrolysis by BSSL compared to 5% hydrolysis without prior exposure. We suggest that previous in vitro studies have largely underestimated the actual degree of intragastric lipolysis that can occur and its activity on long-chain fatty acids; this study indicates the importance of the combined mechanism of gastric lipase and BSSL to fat digestion in the suckling neonate.

Isolation of pure LpB from human serum.

Low density lipoproteins (LDL), even after isolation from a narrow density cut and after several washes by preparative ultracentrifugation, are contaminated by 3-5% non-apoB proteins. Incubation of these LDL with artificial triglyceride-rich lipid emulsions (TGRP) removed all contaminating apoC and also, under certain conditions, apoA proteins. TGRP treatment did not, however, change the lipid composition and the flotation behavior of LDL. Residual apoE and albumin, amounting up to 0.5% of the apoB mass, were resistant to removal by TGRP treatment as well as by heparin-Sepharose column chromatography. ApoE and albumin could only be removed by immunoabsorption.

Expression of a monoclonal antibody-defined aminoterminal epitope of human apoC-I on native and reconstituted lipoproteins.

Nine distinct mouse monoclonal antibodies were produced in two fusions using holo-human very low density lipoprotein (VLDL) as antigen. On immunoblotting first with human VLDL and then with isolated human apoC-I, seven of the antibodies, representing three isotypes, manifested specificity for apoC-I. Two antibodies were directed against apoB. To assess whether the seven anti-apoC-I antibodies were directed against the same or distinctively different epitopes, cross-competition assays were performed wherein 125I-labeled monoclonal antibodies were made to compete with unlabeled antibodies for occupancy on immobilized VLDL-associated apoC-I. All antibodies cross-competed to varying extents implying that they were directed against closely spaced epitopes, but based on these experiments three different epitopes were defined. On immunoblotting with CNBr fragments, all of the epitopes were assigned to the CNBr I fragment of human apoC-I (amino acids 1-38) suggesting that the NH2-terminal region of apoC-I is more immunogenic in mice than other parts of the molecule when apoC-I is associated with VLDL. A competitive solid-phase radioimmunoassay (RIA) was developed employing one of the anti-apoC-I antibodies (A3-4). VLDL was adsorbed to plastic microtiter wells, and a limiting amount of the antibody was reacted with the adsorbed VLDL. The amount of monoclonal antibody that bound to the immobilized VLDL-apoC-I was determined with a 125I-labeled goat anti-mouse IgG antibody. The addition of competitor apoC-I complexed with lipids resulted in reduced binding of the anti-apoC-I antibody to the immobilized VLDL-apoC-I. Competitor complexes consisted of an artificial lipid emulsion (Intralipid) incubated with apoC-I at phospholipid/apoC-I ratios of 1:1 to 60:1 (w/w). As the lipid/protein ratios were increased, the competitive displacement curves produced by the complexes become progressively steeper, while isolated lipid-free apoC-I produced curves with very shallow slopes, suggesting that a conformation-dependent epitope was being probed. Other apoproteins (C-II, C-III, A-I, A-II, and E) whether lipid-free or complexed with lipids did not compete. Fractionation of the 30:1 apoC-I-Intralipid complex by gel permeation chromatography suggested that apoC-I bound to phospholipids was the most effective competitor. This was confirmed by testing of apoC-I-DMPC complexes, which yielded curves that paralleled those produced by apoC-I-Intralipid.(ABSTRACT TRUNCATED AT 400 WORDS)

Bovine milk lipoprotein lipase transfers tocopherol to human fibroblasts during triglyceride hydrolysis in vitro.

Lipoprotein lipase appears to function as the mechanism by which dietary vitamin E (tocopherol) is transferred from chylomicrons to tissues. In patients with lipoprotein lipase deficiency, more than 85% of both the circulating triglyceride and tocopherol is contained in the chylomicron fraction. The studies presented here show that the in vitro addition of bovine milk lipoprotein lipase (lipase) to chylomicrons in the presence of human erythrocytes or fibroblasts (and bovine serum albumin [BSA]) resulted in the hydrolysis of the triglyceride and the transfer of both fatty acids and tocopherol to the cells; in the absence of lipase, no increase in cellular tocopherol was detectable. The incubation system was simplified to include only fibroblasts, BSA, and Intralipid (an artificial lipid emulsion containing 10% soybean oil, which has gamma but not alpha tocopherol). The addition of lipase to this system also resulted in the transfer of tocopherol (gamma) to the fibroblasts. Addition of both lipase and its activator, apolipoprotein CII, resulted in a further increase in the cellular tocopherol content, but apolipoprotein CII alone had no effect. Heparin, which is known to prevent the binding of lipoprotein lipase to the cell surface membrane, abrogated the transfer of tocopherol to fibroblasts without altering the rate of triglyceride hydrolysis. Thus, in vitro tocopherol is transferred to cells during hydrolysis of triglyceride by the action of lipase, and for this transfer of tocopherol to occur, the lipase itself must bind to the cell membrane.

Beta 2-Glycoprotein I. Molecular properties of an unusual apolipoprotein, apolipoprotein H.

beta 2-Glycoprotein I (beta 2GI) has recently been identified as a component of circulating plasma lipoproteins. The metabolic role of this apolipoprotein is not known with certainty; it has been reported that beta 2GI has a high affinity for triglyceride-rich particles, causing their selective precipitation by detergents, and activates lipoprotein lipase in the in vitro hydrolysis of artificial lipid emulsions. In the present report, we have evaluated the secondary, tertiary, and quaternary structure of lipid-free beta 2GI. The weight average molecular weight of beta 2GI, as determined by sedimentation equilibrium measurements, was 43,000 in the presence and absence of denaturing agents. Thus, in contrast to other apolipoproteins, apolipoprotein H (apo-H) does not self-associate in aqueous solution. The circular dichroic spectra of apo-H is unusual in that there are no strong negative bands in the far-ultraviolet region of the spectrum; there is a weak positive maximum at 235 nm and a relatively weak negative maximum at 205 nm. Treatment with guanidinium chloride results in a loss of the positive band with only minor changes in the intensity of the band at 205 nm. Apolipoproteins A-I, A-II, C-I, and E, in contrast, have a secondary structure that contains a high percentage of residues in an alpha-helical configuration and undergo major changes in structure at low concentrations of guanidinium chloride. Highly flexible proteins, such as apolipoproteins A-I, A-II, and C-I, absorb rapidly and reversibly to air-water interfaces, whereas more rigid proteins, such as the classical globular proteins, interact with the interface more slowly and irreversibly. This difference is due to the loosely folded tertiary structure of apolipoproteins and the ease with which they can change structure to accommodate a given environment. The surface activity of beta 2GI at neutral pH resembles that of typical globular proteins. Treatment with acid or base, although causing only minor changes in the circular dichroic spectra, resulted in major increases in the rate of absorption to an air-water interface; under these conditions the rates of absorption were similar to that found for apolipoprotein A-I. These results are consistent with a more flexible structure for beta 2GI in acid or base that resembles other loosely folded apolipoproteins. beta 2GI associates with plasma lipoproteins and satisfies all of the criteria to be classified as an apolipoprotein. The secondary, tertiary, and quaternary structure of beta 2GI is, however, quite different from that of other well characterized apolipoproteins. This difference in structure would be expected to affect protein-lipid interactions; the relationship between apo-H and other apolipoproteins may be similar to that proposed for integral versus peripheral membrane proteins.

Selective degradation of the high density lipoprotein-2 subfraction by heparin-releasable liver lipase

The lipase released from the liver after intravenous injection of heparin (liver lipase, EC 3 .l .1.3) has a broad substrate specificity [l-3]. Hydrolysis of ester bonds in triacylglycerol, diacylglycerols, 1 or 2 monoacylglycerols, pahnitoyl-coenzyme A and phosphatidylcholine (the 1 acyl ester bond) has been demonstrated, using artificial lipid emulsions. Although a role in serum lipoprotein metabolism has generally been considered, the physiological function of this enzyme has not been well established. Evidence has been presented, based on in vivo inhibition of liver lipase by intravenous injection of a specific antiserum in rats, that liver lipase is involved in HDL and possibly LDL-phospholipid catabolism [4-61. Based on these experiments a role of liver lipase in the conversion of HDL-2 into HDL3 was proposed. This hypothesis was developed further by in vitro incubations of liver lipase with rat HDL-2 [7] and by in vivo turnover studies of HDLphospholipids and cholesterol esters [8]. Here, the hypothesis was further investigated. As HDL2 and HDL3 are poorly defmed in rat, we turned to human serum and measured the phospholipase A activity of purified human heparin-releasable liver lipase with isolated HDL-2 and HDL-3. It was found that the rate of phosphatidylcholine hydrolysis with HDL2 as substrate exceeds the rate with HDL3 by a factor of -10. These data provide further evidence for a role of liver lipase in the degradation of HDL-2.

Replacement of endogenous phospholipids in rat plasma lipoproteins during intravenous infusion of an artificial lipid emulsion

Male Wistar rats, weighing 250–300 g, were intravenously infused (0.33 ml/h per 100 g body weight) with an artificial emulsion of soybean triacylglycerols and egg yolk phospholipids (Intralipid) for various periods of time ranging from a few hours to a few days. About 0.5 h after the infusion, the animals were sacrificed, various classes of plasma lipoproteins were isolated by centrifugation, and the total lipid profiles of the fractions were determined by high temperature gas chromatography. The lipoproteins collected after 24 h of infusion were subjected to a complete analysis of the molecular species of the various lipid classes. It was shown that continuous intravenous infusion of Intralipid, despite rapid apparent clearance of the visible lipid particles, resulted in a gradual accumulation of exogenous phosphatidylcholine and sphingomyelin, free cholesterol, and plant sterols in the plasma, which displaced the endogenous phospholipids and sterols from the various lipoproteins. At 24 h, about 70% of the endogenous phospholipid of all the plasma lipoproteins was replaced by egg yolk phospholipids of the Intralipid. Under the same conditions, no displacement nor exchange was observed of endogenous cholesteryl esters for exogenous triacylglycerols in any of the lipoprotein classes. Intralipid infusion for periods up to 3 days results in a limited further displacement of endogenous phospholipids by exogenous lipids in the plasma lipoproteins, but a complete substitution was not achieved because of a continued secretion of lipoproteins containing endogenous phospholipids. The infusion of Intralipid led to a significant increase in the proportion of the phospholipid and free sterol in all lipoproteins, which decreased the calculated diameter of the particles by about one-half. Only minor changes were seen in the lipid to protein ratios of the lipoproteins and in their apoprotein composition.

Electron microscopic observations on cerebral and pulmonary blood vessels after the intravenous injection of artificial lipid emulsions containing barbituric acids.

SummaryBarbiturates dissolved in lipid emulsions are more effective than aqueous preparations of the drugs for intravenous use. To test whether this effect might be related to adhesion of lipid particles to cerebral endothelium, various emulsions containing secobarbital or thiopental were injected intravenously into mice. Blood vessels of the brain and of the lung of animals killed at 5 minutes, 20 minutes and 24 hours were examined by electron microscopy. Though lipid particles were sometimes in contact with the vessel wall, preferential localization or sticking to the endothelium was not observed. Side effects which related to emulsifying agents were platelet aggregation and fat emboli in the lungs.

Modification, sous l’effet de I’alcool, de l’épuration lipidique plasmatique après hyperlipémie induite par le repas gras ou les perfusions d’émulsions lipidiques, chez l’homme

The effects of alcohol on plasma lipids removal were studied in 16 control subjects by comparative measurements of turbidity and triglyceridemia. Alcolhol was administered intravenously for 3 h, either after fat meal or 2 h before artificial lipid emulsion infusion. Compared to the control study, alcohol determines a persistant elevation of induced hyperlipemia and was thought to decrease plasma lipids removal. In fact, rats epididymal fat pads lipoprotein lipase activity is decreased after alcohol intraperitoneal administration. Moreover, in man, the fractional removal constant following an intravenous fat tolerance test was slowed down after alcohol infusion. Both results agree with the decreased removal rate of fat emulsion particles and chylomicrons on account of alcohol.

諸種ラット脂肪肝の初期病変に関する組織化学的研究

To investigate the common early morphologic changes in the 3 models of fatty livers, which were induced with the intravenous injection of artificial lipid emulsion, Fatgen of Dainihon Pharma. Co., and by the intraperitoneal administration of either ethionine or carbon tetrachloride, respectively, the livers of the rats received with these treatments were observed ultrastructurally at the serial intervals after each single chalange. Especially, electron-histochemical observations on lipids (triglyceride esters and phospholipids) and the related enzymes (thiol-esterase and glucose-6-phosphatase) were performed on their livers. Light-microscopic histochemical observations on lipoprotein reactions, sudanophilias, metachromasia of Nile blue sulfate, specific reactions for phospholipids, cholesterols or fatty acids, Tween 60 lipase, thiol-esterase and the other esterases, glucose-6-phosphatase and the other phosphatases, and β-hydroxybutylic dehydrogenase and the other dehydrogenases were also applied to their livers.Histochemical demonstrations for triglycer ide esters and phospholipids were established on both ordinary sections and ultrathin sections, by means of specific enzyme-digestive methods. Purified porcine pancreatic lipase was applied to the reaction for triglyceride esters (TGE-reaction), and snake venom phospholipase was done to the reaction for phospholipids (PL-reaction). Induced fatty acids by the specific digestion were caught in situ by calcium ion and visualized by lead sulfide mathod.

The action of lipoprotein lipase on glyceryl-triphytanate

Tritium-labelled glyceryl-triphytanate and glyceryl- [1- 14C]tripalmitate were incorporated in an artificial lipid emulsion and incubated with human post-heparin plasma containing lipoprotein lipase. The tripalmitin was hydrolysed at the same rate as the bulk of the triglycerides in the emulsion. Glyceryl-triphytanate was not attacked. The results may explain the remarkably low content of phytanic acid in adipose tissue from patients with Refsum's disease.