Biomedical subjects

Yvon A Carpentier

Publications and source records attributed to Yvon A Carpentier.

At least 19 recordsLinked to original sources

PubMed2006

Phospholipid fatty acid pattern and D-glucose metabolism in muscles from omega3 fatty acid-depleted rats.

A depletion in long-chain polyunsaturated omega3 fatty acids may affect fuel homeostasis. In such a perspective, the present study deals mainly with the in vitro fate of D-[U-(14)C]glucose in hemidiaphragms, stretched soleus and plantaris muscle pieces obtained from normal and omega3-depleted rats (second generation) and incubated in the absence or presence of insulin. When so required, the omega3-depleted rats were injected 120 min before sacrifice with either a omega3 fatty acid-rich medium-chain triglyceride:fish oil emulsion (FO) or a control medium-chain triglyceride:olive oil emulsion (OO). The content of the soleus muscle in long-chain polyunsaturated omega3 fatty acids was severely decreased in the omega3-depleted rats, and modestly albeit significantly increased after injection of FO to these animals. In stretched soleus muscles from OO-injected omega3-depleted rats, the absolute values for glycogen synthesis measured in the absence or presence of insulin were about twice higher than in normal animals. In the OO-injected omega3-depleted rats, insulin augmented the output of (14)C-labelled amino acids, whilst such was not the case in normal animals. These and other findings suggest a lower catabolism of D-glucose relative to the anabolic process of glycogen synthesis and a lower availability of endogenous amino acids in the muscles of omega3-depleted rats, as compared to those of control animals. The prior injection of FO to the omega3-depleted rats restored a normal value for the paired ratio between the output of (14)C-labelled amino acids and acidic metabolites, but further increased glycogen net synthesis. It is proposed, therefore, that the perturbation of d-glucose metabolism in muscles from omega3-depleted rats involves a multifactorial determinism, only some of the concerned factors being susceptible to rapid correction after enrichment of cell phospholipids in long-chain polyunsaturated omega3 fatty acids.

Animals↗

PubMed2006

Brain phospholipid and triglyceride fatty acid content and pattern in Type 1 and Type 2 diabetic rats.

The liver phospholipid and triglyceride content and/or fatty acid pattern differ(s) not solely in normal versus diabetic rats, but also in distinct rat models of diabetes mellitus. The present study reveals that a comparable situation prevails in the brain. Fed and overnight fasted female normal rats (N) and Goto-Kakizaki rats (GK), as well as fed rats rendered diabetic by a prior injection 3 days before sacrifice of streptozotocin (STZ) were examined. The brain phospholipid content, expressed as milligrams of fatty acids per gram wet weight, was comparable in all groups of rats, with an overall mean value of 31.2+/-0.8 (n=22). The GK rats differed from N and STZ rats by lower C18:0/C18:1omega9 and C18:2omega6/C18:3omega6 ratios and a lower C20:5omega3 content of brain phospholipids. The total amount of fatty acids in triglycerides was 7-8 times higher in GK than N and STZ rats. The GK rats differed from N and STZ rats by lower C16:0/C16:1omega7, C18:0/C18:1omega9 and (C16:0+C16:1omega7)/(C18:0+C18:1omega9) ratios in triglycerides. These findings extend to the brain, the knowledge of alterations in phospholipid and triglyceride content and/or fatty acid pattern in GK rats, as compared to N or STZ rats. The former rats indeed displayed: (i) an apparently increased activity of Delta9- and Delta6-desaturases, as suggested by the phospholipid measurements, and a decreased C20:5omega3 content in such phospholipids; (ii) a dramatic increase in brain triglyceride content; and (iii) an increased activity of Delta9-desaturase, as well as elongase, as judged from the triglyceride data.

Adipose Tissue↗

PubMed2006

n-3 fatty acids and the metabolic syndrome.

The metabolic syndrome is defined as the coexistence of 3 or more components, some of which indicate alterations in glucose and lipid metabolism. The prevalence of the metabolic syndrome is rapidly increasing in relation to obesity, and it is considered to be an important predictor of cardiovascular disease. Increased intakes or supplements of n-3 marine fatty acids may improve defects in insulin signaling and prevent alterations in glucose homeostasis and the further development of type 2 diabetes. This is largely mediated through a reduction in fatty acid accumulation in muscle and liver. n-3 Polyunsaturated fatty acids (n-3 PUFAs) reduce plasma triacylglycerols and improve the lipoprotein profile by decreasing the fraction of atherogenic small, dense LDL. However, n-3 PUFAs do not lower LDL cholesterol. These effects are likely mediated through the activity of transcription factors relating to expression of genes involved in lipid oxidation and synthesis. Other pleiotrophic effects of n-3 PUFAs may contribute to decreasing the burden of the metabolic syndrome, such as modulating inflammation, platelet activation, endothelial function, and blood pressure. Although studies comparing the effect of both major n-3 PUFAs are limited, docosahexaenoic acid appears at least as efficient as eicosapentaenoic acid in correcting several risk factors. The use of n-3 PUFAs should be considered in more global strategies including changes in lifestyle, such as adhering to a healthy Mediterranean type of diet and practicing regular physical exercise.

Blood Glucose↗

PubMed2006

Triglycerides in fish oil affect the blood clearance of lipid emulsions containing long- and medium-chain triglycerides in mice.

Lipid emulsions containing long-chain triglycerides (LCT) and medium chain triglycerides (MCT) are widely used in parenteral nutrition. Recently, fish oil (FO) triglyceride (TG)-derived emulsions are considered therapeutic because of their many beneficial biological modulatory actions. We investigated in mice whether adding 10% FO to an intravenous lipid emulsion with MCT and LCT (MCT:LCT:FO -50:40:10% by wt) would affect particle blood clearance and tissue targeting in comparison to LCT (100% by wt) and MCT:LCT (50:50% by wt) emulsions. The 3 emulsions were labeled with [3H] cholesteryl oleoyl ether and administered by bolus injection (400 microg TG/mouse) to C57BL/6J mice. Contributions of LDL receptor (LDL-R) and LDL-R-related protein to emulsion catabolism were assessed using LDL-R-deficient mice and preinjection of lactoferrin, and the effects of lipoprotein lipase (LPL) were determined by preinjection of heparin and Triton WR 1339. Although fractional catabolic rates did not differ among the 3 emulsions, blood removal at each time point after injection was greater for MCT:LCT:FO particles due to their higher initial margination volume. Compared with MCT:LCT and LCT emulsions, patterns of tissue uptake of the MCT:LCT:FO emulsions were different, e.g. MCT:LCT:FO emulsion particle uptake was lower in heart, adipose tissue, and muscle, and higher in lung, and the removal of MCT:LCT:FO emulsion particles was less dependent on LPL, LDL-R, and lactoferrin-sensitive pathways. These data suggest that the addition of a low percentage of FO to MCT:LCT emulsions substantially changes their particle clearance and tissue uptake mechanisms.

Animals↗

PubMed2006

Pancreatic islet function in omega3 fatty acid-depleted rats: Glucose metabolism and nutrient-stimulated insulin release.

In order to gain information on the determinism of the perturbation of fuel homeostasis in situations characterized by a depletion in long-chain polyunsaturated omega3 fatty acids (omega3), the metabolic and hormonal status of omega3-depleted rats (second generation) was examined. When required, these rats were injected intravenously 120 min before sacrifice with a novel medium-chain triglyceride-fish oil emulsion able to provoke a rapid and sustained increase of the omega3 content in cell phospholipids. The measurement of plasma glucose, insulin, phospholipid, triglyceride, and unesterified fatty acid concentration indicated modest insulin resistance in the omega3-depleted rats. The plasma triglyceride and phospholipid concentrations were decreased in the omega3-depleted rats with abnormally low contribution of omega3 in both circulating and pancreatic islet lipids. The protein, insulin, and lipid content of the islets, as well as their intracellular and extracellular spaces, were little affected in the omega3-depleted rats. The metabolism of D-glucose in the islets of omega3-depleted rats was characterized by a lesser increase in D-[5-3H]glucose utilization and D-[U-14C]glucose oxidation in response to a given rise in hexose concentration and an abnormally low ratio between D-glucose oxidation and utilization. These abnormalities could be linked to an increased metabolism of endogenous fatty acids with resulting alteration of glucokinase kinetics. The release of insulin evoked by D-glucose, at a close-to-physiological concentration (8.3 mM), was increased in the omega3-depleted rats, this being considered as consistent with their insulin resistance. Relative to such a release, that evoked by a further rise in D-glucose concentration or by non-glucidic nutrients was abnormally high in omega3-depleted rats, and restored to a normal level after of the intravenous injection of the omega3-rich medium-chain triglyceride-fish oil emulsion. Because the latter procedure failed to correct the perturbation of D-glucose metabolism in the islets of omega3-depleted rats, it is proposed that the anomalies in the secretory behaviour of islets in terms of their response to an increase in hexose concentration or non-nutrient secretagogues is mainly attributable to alteration in K+ and Ca2+ handling, as indeed recently documented in separate experiments.

Animals↗

PubMed2006

Sustained enrichment of liver phospholipids and triglycerides in eicosapentaenoate after a bolus intravenous injection of a medium-chain triglycerides:fish oil emulsion to streptozotocin (Type 1) and Goto-Kakizaki (Type 2) diabetic rats.

This study deals with the sustained enrichment of liver phospholipids and triglycerides in long-chain polyunsaturated omega3 fatty acids (omega3) found after the bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion (MCT:FO) to streptozotocin (Type 1) and Goto-Kakizaki (Type 2) diabetic rats. Twenty hours after injection of the MCT:FO emulsion, the relative concentration of omega3 was indeed higher in liver phospholipids and triglycerides than that found in rats injected with either saline or a control medium-chain triglyceride:long-chain triglyceride emulsion. This coincided with a decrease in the ponderal percentage of C18:3omega3, C20:4omega6 and/or C22:4omega6 in liver triglycerides. The present study further documents differences between streptozotocin-induced and Goto-Kakizaki diabetic rats in terms of body weight, glycemia, liver triglyceride content and the fatty acid pattern of both liver phospholipids and triglycerides, as well as a close correlation in the latter animals between liver and plasma phospholipids or triglycerides as far as the ratio in the relative concentration of selected fatty acids representative of desaturase and elongase activities is concerned. In light of these and previous findings, it is proposed that the beneficial metabolic and functional events of the MCT:FO emulsion may display not solely a rapid but also sustained time course.

Animals↗

PubMed2006

Protection of aortic endothelial function in both normal and diabetic rats by intravenous bolus injection of a medium-chain triglyceride: fish oil emulsion.

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion (MCT:FO) was recently proposed as a tool to provoke a rapid and sustained increase of cell phospholipid content in long-chain polyunsaturated omega3 fatty acids, for instance in selected subjects prior to anesthesia and surgery. In this study, therefore, the possible protective effect of MCT:FO upon aortic endothelial function was investigated in both normal and diabetic rats. The animals were injected intravenously 20 h before sacrifice with 1.0 ml of either saline, MCT:FO or a control medium-chain triglyceride:long-chain triglyceride emulsion. The vasomotor response of isolated aortic rings was then explored by assessing the relaxation provoked by increasing concentrations of acetylcholine in rings contracted with phenylephrine. Such measurements were performed before and after exposure of the aortic rings to suitable concentrations of oxidized LDL. In both normal and diabetic rats, the prior injection of the MCT:FO emulsion protected the aortic rings against the deleterious effect of oxidized LDL. In the diabetic rats, a beneficial effect of the MCT:FO emulsion was even observed prior to exposure of the aortic rings to oxidized LDL. These findings support the view that this novel procedure is indeed appropriate to protect endothelial function against oxidative stress.

Acetylcholine↗

PubMed2006

Preclinical investigations of a medium-chain triglyceride:fish oil emulsion. I. Effects of bovine milk lipoprotein lipase on lipid composition.

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion (MCT:FO, 8:2, w:w) was recently found to increase within 60 min the leucocyte and platelet phospholipid content of long-chain polyunsaturated omega3 fatty acids. The present report deals with the effects of bovine milk lipoprotein lipase on the lipid composition of this emulsion. The results are compared to those obtained with either a pure fish oil emulsion or a medium-chain triglyceride: long-chain triglyceride:fish oil emulsion (MLF, 5:4:1). Emphasis is placed on i) differences in the fate of distinct fatty acids initially present in the triglycerides, di glycerides and phospholipids, ii) the generation of unesterified fatty acids relative to their initial content in each emulsion, and iii) the time course for these various events. The comparison between the three emulsions under consideration also provides information relevant to their respective sensitivity to lipoprotein lipase and suitability in terms of the generation of distinct unesterified fatty acids, including long-chain polyunsaturated omega3 fatty acids. Furthermore, attention is drawn to the greater efficiency for the hydrolysis of fatty acids from diglycerides as compared to triglycerides and a transient increase in the paired C8:0/C10:0 ratio in the diglycerides generated from the MCT:FO or MLF emulsion. The present study thus affords novel information relevant to the possible use of the MCT:FO emulsion in human subjects.

Animals↗

PubMed2006

Rapid changes in liver lipid composition and pancreatic islet K+ handling and secretory behaviour provoked by the intravenous administration of a medium-chain triglyceride: fish oil emulsion to long-chain polyunsaturated omega3 fatty acid-depleted rats.

Second generation rats depleted in long-chain polyunsaturated omega3 fatty acids are currently used as an animal model for the insufficient dietary supply of such fatty acids often prevailing in Western populations. The present study deals mainly with the effects of a novel medium-chain triglyceride: fish oil emulsion (MCT:FO), as compared to a control medium-chain triglyceride:olive oil emulsion (MCT: OO), administered as an intravenous bolus to the omega3-depleted rats 60-120 min before sacrifice upon selected biochemical and biophysical variables. The major findings consisted of a severe decrease of the omega3 fatty acid content of liver lipids in non-injected omega3-depleted rats and its partial correction after injection of the MCT:FO emulsion. The omega3-depleted rats also displayed liver steatosis, increased incorporation of long-chain polyunsaturated omega6 fatty acids in liver phospholipids and increased activity of liver Delta9-desaturase. As judged from the effects of ouabain upon 86Rb net uptake by isolated pancreatic islets, the activity of Na+,K+-ATPase was virtually abolished in the omega3-depleted rats. The latter defect was corrected by prior intravenous injection of the MCT:FO emulsion, this coinciding with suppression of the excessive secretory response to a number of insulin secretagogues otherwise observed in the islets of omega3-depleted rats injected or not with the MCT:OO emulsion.

Animals↗

PubMed2006

Preclinical investigations of a medium-chain triglyceride:fish oil emulsion III. Experiments in cultured endothelial cells.

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion was recently reported to provoke a rapid and sustained increase in the cell phospholipid content of long-chain polyunsaturated omega3 fatty acids in both rats and human subjects. This report deals mainly with a comparison between this and other emulsions, as well as albumin-bound omega3 fatty acids, in terms of the time course, reversibility and concentration dependency for the incorporation of the omega3 fatty acids in the phospholipids of cultured endothelial cells. The results document that the new emulsion is quite efficient for a rapid and sustained enrichment of phospholipids in long-chain polyunsaturated omega3 fatty acids. The potential beneficial effects of such an enrichment in terms of aortic endothelial and cardiac function are emphasized.

Animals↗

PubMed2006

Fatty acid content and pattern of epididymal and parametrial adipose tissue lipids in streptozotocin (type 1) and Goto-Kakizaki (type 2) diabetic rats.

Attention was recently drawn to differences in the fatty acid pattern of liver phospholipids and triglycerides in animal models of type 1 and type 2 diabetes. The present study extends this knowledge to epididymal or parametrial adipose tissue lipids. The fatty acid pattern of such lipids was established in four fed female normal rats, four overnight fasted female normal rats, six fed female rats rendered diabetic by an injection of streptozotocin 3 days before sacrifice (STZ rats), and four female and four male Goto-Kakizaki rats (GK rats) also examined in the fed or fasted state. In addition to the fasting-induced and diabetes-related changes in plasma D-glucose and insulin concentrations, differences in either the weight percentage of fatty acids or the paired ratio between distinct fatty acids were often encountered. For instance, in the GK rats, gender differences were observed in the weight percentage of C18:2omega6, as well as C18:2omega6/C18:3omega6, C18:3omega6/C20:4omega6, C20:5omega3/C22:5omega3 and C22:5omega3/C22:6omega3 ratios. When compared to normal rats, the activity of Delta9-desaturase was markedly increased in GK rats and, to a lesser extent, in STZ rats. Starvation also increased to some extent the activity of Delta9-desaturase. The relative content of C22:6omega3 was also higher in diabetic than in normal rats. Further differences between GK and STZ rats concerned the generation of C18:3omega6 from C18:2omega6, C20:4omega6 from C18:3omega6, and C20:5omega3 from C18:3omega3. Several differences found in the adipose tissue of GK versus STZ rats were reminiscent of those recently identified in the liver triglycerides of these two types of diabetic animals, suggesting a common regulatory mechanism, possibly linked to the higher insulinemia of GK rats versus STZ rats.

Adipose Tissue↗

PubMed2005

Cis-9, trans- 11 and trans-10, cis-12 conjugated linoleic acid (CLA) do not affect the plasma lipoprotein profile in moderately overweight subjects with LDL phenotype B.

BACKGROUND: Results of a pilot study suggested that cis-9, trans-11 conjugated linoleic acid (CLA) improved LDL phenotype in moderately overweight subjects with LDL phenotype B. OBJECTIVE: Initiated by the results of this pilot study, we have specifically designed a study to test the hypothesis that cis-9, trans-11 conjugated linoleic acid improves LDL phenotype in moderately overweight subjects with LDL phenotype B. Effects on the serum lipid profile, on plasma glucose and insulin concentrations, and on clinical parameters were also examined. DESIGN: Volunteers with LDL phenotype B were divided into three groups consuming daily a drinkable dairy product not enriched with CLA (placebo, n = 34), the same dairy product enriched with 3g c9, t11 CLA (n = 34), or the dairy product enriched with 3g t10, c12 CLA (n = 19) for 13 weeks. RESULTS: Median changes in the proportions of plasma small dense LDL were -2.0% in the control group and -0.1% in the c9, t11 CLA and t10, c12 CLA groups (p = 0.981 for the differences between the groups). c9, t11 CLA or t10, c12 CLA did also not affect serum concentrations of LDL and HDL cholesterol, and of triacylglycerol, and plasma concentrations of glucose and insulin. CONCLUSIONS: In humans with LDL phenotype B, c9, t11 CLA and t10, c12 CLA do not beneficially change risk factors for cardiovascular disease or diabetes.

Adult↗

PubMed2005

In vivo and in vitro properties of an intravenous lipid emulsion containing only medium chain and fish oil triglycerides.

BACKGROUND & AIMS: The triglyceride (TG) fatty acyl composition in lipid emulsions influences their metabolism. Little is known about the effects of long chain omega-3 polyunsaturated fatty acids (PUFA) on lipid emulsion metabolism. We investigated possible differences between omega-3 containing emulsions in their metabolism and tissue-targeting in vivo in a mouse model, and in vitro using lipolysis and cell culture experiments. METHODS: Soy oil (LCT), MCT/LCT/omega-3 (5:4:1, wt/wt/wt), and MCT/omega-3 (8:2, wt/wt) emulsions were radiolabeled with nondegradable 1alpha,2alpha (n)-[3H] cholesteryl oleoyl ether to trace core particle metabolism in C57BL/6J mice following a bolus injection. Blood samples obtained over 25 min and extracted organs were used to measure the tissue distribution of lipid emulsion particles. Lipoprotein lipase (LpL)-mediated hydrolysis experiments and cell uptake studies in cultured J774 murine macrophages were also performed. RESULTS: Blood clearance of 8:2 was 13.4% and 29.8% faster compared to 5:4:1 and LCT, respectively. LCT had greatest liver uptake. LpL-mediated hydrolysis was greatest in 8:2 and lowest in LCT. Overall, cell TG accumulation in the presence of apolipoprotein E was least with 8:2. CONCLUSIONS: Our data shows that 8:2 had the most efficient blood clearance but less hepatic uptake in vivo. In vitro, 8:2 had both highest hydrolysis by LpL and intracellular TG utilization in the presence of apoE. Thus, an 8:2 lipid emulsion undergoes efficient blood clearance and may direct omega-3 PUFA more towards extrahepatic tissues.

Animals↗

PubMed2005

Vitamin E: absorption, plasma transport and cell uptake.

PURPOSE OF REVIEW: Large-scale clinical trials have failed to demonstrate a benefit for vitamin E supplementation in cardiovascular prevention. This contrasts with previous epidemiological studies indicating that individuals with high vitamin E status benefit from protection against chronic illnesses, including cardiovascular diseases. These conflicting results suggest that the metabolism of supplemental versus naturally delivered vitamin E and their potential roles, other than a potent antioxidant action, are not fully understood. The purpose of this review is to provide an update on current knowledge on the intestinal absorption of vitamin E, its plasma transport and its supply to cells. The review will also discuss the intravascular metabolism of intravenously delivered vitamin E. RECENT FINDINGS: Although the luminal digestion of vitamin E is fairly well understood, several pathways regulating net vitamin E absorption remain to be elucidated. In several cell types, cholesterol and vitamin E share common mechanisms for cellular uptake (scavenger receptor B type I and LDL receptors) and efflux (ABCA1 transporters). The role of specific binding proteins in alpha-tocopherol intracellular trafficking is increasingly being understood, leading to new insights into the non-antioxidant functions of vitamin E. SUMMARY: Substantial progress has been made in characterizing the plasma transport of vitamin E and its delivery to cells. Mechanisms regulating the balance between the cellular uptake and efflux of vitamin E are under investigation. Vitamin E is not only an antioxidant but may also modulate pathways of cell signalling and gene expression. The translation of this new knowledge into clinical studies will help define future indications for vitamin E supplementation.

Antioxidants↗

PubMed2004

Using different intravenous lipids: underutilized therapeutic approaches?

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Fat Emulsions, Intravenous↗

PubMed2002

Omega-3 triglycerides modify blood clearance and tissue targeting pathways of lipid emulsions.

Omega-3-rich (n-3) triglycerides (TG) are increasingly recognized as having modulating roles in many physiological and pathological conditions. We questioned whether the catabolism of lipid emulsions would be changed after enrichment with fish oil (n-3) TG as compared to enrichment with omega-6-rich soy oil (n-6) TG. Phospholipid-stabilized emulsions of n-3 TG and n-6 TG were labeled with [(3)H]cholesteryl oleoyl ether and administered by bolus injection to wild-type (WT) mice, mice lacking the low-density lipoprotein receptor (LDL-R) (LDL-R -/-), and apolipoprotein E (apoE) knockout mice (apoE -/-). The effects of exogenous apoE, heparin, Triton WR 1339, and lactoferrin on catabolism of emulsions were also assayed. n-3 TG emulsions were cleared faster from blood and had different extrahepatic tissue targeting compared to n-6 TG emulsions. In apoE -/- and LDL-R -/- mice, blood clearance of n-6 TG emulsions slowed with decreased liver uptake, but no changes were observed in n-3 TG emulsion clearance and tissue uptake compared to WT mice. In WT mice, addition of exogenous apoE to the emulsion increased liver uptake of n-6 TG emulsions but had no impact on n-3 TG emulsions. Pre-injection of heparin increased and Triton WR 1339 and lactoferrin decreased blood clearance of n-6 TG emulsions with little or no effect on n-3 TG emulsions. Liver uptake of n-6 TG emulsions increased after heparin injection and decreased after Triton WR 1339 injection, but uptake of n-3 TG emulsions was not changed. These data show that the catabolism of n-3 TG emulsions and the catabolism of n-6 TG emulsions occur via very different mechanisms. Removal of chylomicron-sized n-6 TG emulsions is modulated by lipoprotein lipase (LPL), apoE, LDL-R, and lactoferrin-sensitive pathways. In contrast, clearance of chylomicron-sized n-3 TG emulsions relies on LPL to a very minor extent and is independent of apoE, LDL-R, and lactoferrin-sensitive pathways.

Animals↗

PubMed2002

LDL binding to lipid emulsion particles: effects of incubation duration, temperature, and addition of plasma subfractions.

Lipid emulsions used in parenteral nutrition interact with lipoproteins leading to exchanges of lipids and acquisition of several apolipoproteins (apo). It has been previously observed that, during in vitro incubation of emulsions with purified LDL, a variable fraction of LDL binds to TG-rich emulsion particles. The purpose of this study was to better characterize such an interaction. Two emulsions containing 20% soybean oil (Endolipid, B. Braun AG, Melsungen, Germany) or fish oil were incubated with LDL, either alone or in the presence of various plasma subfractions, for different durations and at different temperatures. The fraction named M-LE (containing TG-rich particles modified after incubation) was separated by ultracentrifugation or gel filtration chromatography, and the apoB content was measured as an index of LDL binding to TG-rich emulsion particles. The formation of such complexes was visualized by freeze-fracture electron microscopy. LDL binding was not influenced by the method used for M-LE isolation. Binding occurred quickly, did not increase with prolonged incubation, was inversely related to increasing incubation or ultracentrifugation temperature, and withstood 40 h of ultracentrifugation at 163,000 x g. The presence of glycerol or excess phospholipids in the emulsion did not markedly affect the formation of the complexes. In contrast, adding very small amounts of lipoprotein-poor plasma (d > 1.210 g/mL) or HDL markedly reduced the process, and albumin had no effect. The TG composition of the emulsion influenced the binding of LDL to TG-rich particles, since more apoB was found in M-LE from fish oil than from soybean oil emulsion.

Adult↗

PubMed2002

Changes in the concentration and composition of plasma lipoproteins during the acute phase response.

The acute phase reactions, associated with injury, inflammation, or sepsis, markedly affect the concentration and composition of plasma lipids and lipoproteins. Hepatic production of triglycerides and very low density lipoprotein formation are increased, but do not necessarily result in high plasma triglyceride levels. In contrast, all conditions lower plasma cholesterol by decreasing its content in both low-density and high-density lipoproteins. In addition, substantial changes in protein and lipid composition of lipoproteins are observed that may redefine the function of these particles, but also increase their atherogenic and inflammatory properties.

Acute-Phase Reaction↗