PubMed Health⌕ Search

Biomedical subjects

J L Paul

Publications and source records attributed to J L Paul.

At least 19 recordsLinked to original sources
PubMed2001

Analysis of the relationship between triglyceridemia and HDL-phospholipid concentrations: consequences on the efflux capacity of serum in the Fu5AH system.

The high triglyceride/low HDL-cholesterol trait is a common finding in the general population. The aim of the present study was to analyze and interpret the relationships between triglycerides (TG), HDL-related parameters and serum cholesterol efflux potential in an asymptomatic population including both normo- and hyperlipidemic individuals. In a large sample (n = 1143) of this population, there was a negative correlation between TG and HDL-cholesterol (HDL-C) (r = -0.49, P<0.0001) whereas the negative correlation between TG and HDL-phospholipid (HDL-PL) (r = -0.29, P<0.0001) was weaker, leading to a strong positive correlation between TG and HDL-PL/C ratio (r = 0.58, P<0.0001). Thus, increased TG concentrations were associated with an enrichment of HDL with PL. Since we have demonstrated previously that HDL-PL is the major determinant for cholesterol efflux potential from Fu5AH rat hepatoma cells, we determined the effect of the variations in HDL lipid composition on the cholesterol efflux capacity in a subsample of 198 subjects. Compared with normolipidemic subjects (NLP) (TG< or = 1.7 mmol/l; LDL-C< or = 4.1 mmol/l, n=58), hypertriglyceridemic subjects (HTG) (TG>1.7 mmol/l, n=63) exhibited lower HDL-C levels (1.08+/-0.21 vs. 1.25+/-0.32, P=0.0003) whereas they showed similar HDL-PL concentrations (1.25+/-0.21 vs. 1.25+/-2.7) and, thus, higher HDL-PL/C ratio (1.17+/-0.15 vs. 1.02+/-0.14, P=0.0001). The relative efflux capacity of serum measured in the Fu5AH system (5% serum, 4 h incubation at 37 degrees C) was on average identical in the HTG and NLP groups. Thus, this study provides evidence that despite decreased HDL concentrations, as determined routinely by the HDL-C assay, some HTG subjects maintained serum cholesterol efflux capacity thanks to the enrichment of HDL with PL.

Adult↗
PubMed2001

Erythrocyte, but not plasma, vitamin E concentration is associated with carotid intima-media thickening in asymptomatic men at risk for cardiovascular disease.

Epidemiological data regarding the preventive role of vitamin E in the pathogenesis of atherosclerosis have yielded conflicting results, possibly because endpoints considered were clinical events but not detection of atherosclerosis per se. Otherwise, it has been suggested that the measure of the erythrocyte alpha-tocopherol level may be more suitable to assess the human tocopherol status than its plasma level. We investigated the association between early atherosclerosis in superficial arteries assessed noninvasively and the alpha-tocopherol status in 261 asymptomatic men at risk for cardiovascular disease. alpha-Tocopherol concentrations in plasma, HDL, and erythrocytes were determined using a reverse-phase HPLC method. Detection of carotid plaques and measure of carotid intima-media thickness (IMT) were performed using high-resolution B-mode ultrasonography. The main result of this study is the observation of a negative correlation (P<0.01) between carotid IMT and erythrocyte alpha-tocopherol concentration, independently of conventional cardiovascular risk factors, whereas no such association has been found with plasma (total or HDL) alpha-tocopherol concentrations. No association has been evidenced between alpha-tocopherol concentrations and carotid plaques. These results emphasize the primary protective role of vitamin E in the early phases of atherosclerosis and the significance of the erythrocyte alpha-tocopherol concentration as a marker of atherosclerosis.

Arteriosclerosis↗
PubMed2001

Homocysteine-induced decrease in endothelin-1 production is initiated at the extracellular level and involves oxidative products.

The increased cardiovascular risk associated with hyperhomocysteinemia has been partly related to homocysteine (Hcy)-induced endothelial cell dysfunction. However, the intra or extracellular starting point of the interaction between Hcy and endothelial cells, leading to cellular dysfunction, has not yet been identified. We investigated the effects of both intracellular and extracellular Hcy accumulation on endothelin-1 (ET-1) synthesis by cultured human endothelial cells. Incubation of cultures with methionine (1.0 mmol x L(-1)) for 2 h induced a slight increase in cellular Hcy content but no change in ET-1 production. Incubation of cells with Hcy (0.2 mmol x L(-1)) led to a significant fall in ET-1 generation, accompanied by a significant increase in cellular Hcy content. Addition of the amino-acid transport system L substrate 2-amino-2-norbornane carboxylic acid had no effect on the Hcy-induced decrease in ET-1 production but significantly inhibited the Hcy-induced increase in the cellular Hcy content. Incubation of cells with a lower Hcy concentration (0.05 mmol x L(-1)) also reduced ET-1 production without increasing the cellular Hcy content. Co-incubation with extracellular free-radical inhibitors (superoxide dismutase, catalase and mannitol) markedly reduced the effect of Hcy on ET-1 production. Thus, it is extracellular Hcy accumulation that triggers the decrease in ET-1 production by endothelial cells through oxidative products.

Antioxidants↗
PubMed2001

Basal and postprandial serum-promoted cholesterol efflux in normolipidemic subjects: Importance of fat mass distribution.

Excess of adipose tissue may affect the reverse cholesterol transport mediated by high-density lipoprotein (HDL). Impairments in this system may be one possible factor favoring atherosclerosis development in obesity. To investigate if gender and regional fat mass distribution independently influence reverse cholesterol transport (RCT), we studied in vitro the capacity of serum to promote the cell cholesterol efflux. Measurements were performed both in the fasting state and in the postprandial state, a setting known to stimulate cholesterol transport and altered in obesity. Thirteen obese women with an android phenotype, waist-to-hip ratio (WHR): 0.98 to 0.85 and 51 normal-weight subjects: 25 women and 26 men, with a similar WHR range: 0.96 to 0.67, were recruited. All the participants were normolipoproteinemic in the fasting state and were given an oral fat load. Blood samples were taken before giving the oral fat load and after every 2 hours. The measurements of the ability of serum to promote cholesterol efflux from cells were performed using 3H-cholesterol labeled Fu5AH hepatoma cells in the fasting state 6 and 8 hours after the lipid rich meal. Incremental serum triglyceride (TG), area under the curve (iAUC) and AUC of retinyl palmitate (RP) for the obese women and nonobese subjects were similar. Basal cholesterol efflux was reduced in obese women compared with normal-weight women (26.75% +/- 3.1% v 30.81% +/- 4.2%, P =.004). However, the magnitude of cholesterol efflux promoted by whole serum increased similarly in all the groups. In the subjects with similar WHR, no gender difference was observed in the postprandial TG response and in the first step of RCT. Multivariate regression analyses indicated that plasma HDL-cholesterol (HDL-C) concentration is the best predictor of cholesterol efflux in the fasting state with an independent mild additive effect of WHR. Conversely, postprandial efflux appeared to be mostly related to the WHR with a mild additive effect of HDL-C. Our results indicate that alterations in the first step of RCT can occur in normolipidemic obese subjects and are tightly associated with the abdominal distribution of fat mass. Android obesity in women brings them to the level of men with respect to RCT.

Administration, Oral↗
PubMed2001

Analysis of the postprandial lipid metabolism: use of a 3-point test.

OBJECTIVES: The oral fat load tests used to study postprandial lipemia are complex and costly and time consuming. A simplified fat load test could be more convenient and more appropriate in routine clinical practice because of the number of lipid determinations required. RESEARCH DESIGN AND METHODS: We evaluated the capacity of a postprandial test model that reduced the number of blood samples taken in thirty three normal weight controls and 17 normotriglyceridemic obese patients (study 1), 10 normolipidemic type 2 diabetic patients and 7 healthy controls (study 2), and 10 hyperlipidemic type 2 diabetic patients studied before and after hypolipidemic therapy (study 3). Blood samples were taken before and up to 8 hours after giving the oral fat load containing retinol. Triglyceride (TG) and retinyl palmitate (RP) concentrations in the plasma, chylomicrons (CM) and non-chylomicron (nCM) fractions were measured. Postprandial lipid responses using conventional area under the curves (AUCc using 5 to 7 lipid determinations) were compared to a 3-point test that uses only three sample points to predict the area under the curve (AUCp: triglycerides at T0, triglycerides at average peak-time (T4), and triglycerides at T8). RESULTS: The AUCc and AUCp for triglycerides and retinyl palmitate were highly correlated in each of the groups and whatever the lipid subfraction (r=0.664 - 0.995, p<0.0001). When incremental AUC (iAUC) were used, the coefficients of correlation for triglycerides remained highly significant between iAUCc and iAUCp (r=0.718 - 0.979, p<0.01 - 0.0001). The same trend of differences was found between cases and controls when AUCp was used instead of AUCc. The means of differences between AUCc and AUCp for triglyceride values were small (0.34 - 0.74 mmol/L.h), and the confidence intervals were acceptable considering the range of the AUCs values (5.60 to 79.8 mmol/L.h for plasma triglycerides). CONCLUSIONS: We found that data obtained with a simplified model of AUC using only 3 points to analyse postprandial lipemia are well correlated with those obtained by conventional AUC, and that the AUCp allows to the same conclusions as AUCc when healthy subjects were compared to patients with altered postprandial metabolism. Thus AUCp may be a good evaluation of the AUCc, and the simplified 3-point protocol may well be used and suitable for studies on large groups of subjects who are eligible for an oral fat load test.

Area Under Curve↗
PubMed2001

Increased plasma apoA-IV level is a marker of abnormal postprandial lipemia: a study in normoponderal and obese subjects.

Plasma apolipoprotein A-IV (apoA-IV) levels are found elevated in hypertriglyceridemic patients. However, the relationship between plasma apoA-IV level and postprandial lipemia is not well known and remains to be elucidated. Thus, our objective was to study the relationship between plasma apoA-IV and postprandial TG after an oral fat load test (OFLT). Plasma apoA-IV was measured at fast and during an OFLT in 16 normotriglyceridemic, normoglucose-tolerant android obese subjects (BMI = 34.6 +/- 2.9 kg/m(2)) and 30 normal weight controls (BMI = 22.2 +/- 2.3 kg/m(2)). In spite of not statistically different fasting plasma TG levels in controls and obese patients, the former group showed an altered TG response after OFLT, featuring increased nonchylomicron TG area under the curve (AUC) compared with controls (516 +/- 138 vs. 426 +/- 119 mmol/l x min, P < 0.05). As compared to controls, obese patients showed increased apoA-IV levels both at fast (138.5 +/- 22.4 vs. 124.0 +/- 22.8 mg/l, P < 0.05) and during the OFLT (apoA-IV AUC: 79,833 +/- 14,281 vs. 68,176 +/- 17,463 mg/l x min, P < 0.05). Among the whole population studied, as among the control and obese subgroups, fasting plasma apoA-IV correlated significantly with AUC of plasma TG (r = 0.60, P < 0.001), AUC of chymomicron TG (r = 0.45, P < 0.01), and AUC of nonchylomicron TG (r = 0.62, P < 0.001). In the multivariate analysis, fasting apoA-IV level constituted an independent and highly significant determinant of AUC of plasma TG, AUC of chymomicron TG, AUC of nonchylomicron TG, and incremental AUC of plasma TG. In conclusion, we show a strong link between fasting apoA-IV and postprandial TG metabolism. Plasma fasting apoA-IV is shown to be a good marker of TG response after an OFLT, providing additional information on post-load TG response in conjunction with other known factors such as fasting TGs.

Adult↗
PubMed2000

Interactions between herpes simplex virus type 2 and human immunodeficiency virus type 1 infection in African women: opportunities for intervention.

Sexually transmitted diseases (STDs) are cofactors for human immunodeficiency virus (HIV) transmission, but the specific role of herpes simplex virus type 2 (HSV-2) is unclear. This study aimed to examine the in vivo relationships between HSV-2 and HIV-1 in 300 women in Bangui, Central African Republic. Sera were tested for syphilis, HIV-1, HSV-2 antibody, and levels of vitamins A and E. Genital specimens were tested for other STDs. HSV-2 DNA and HIV-1 RNA were quantified in cervicovaginal lavage. The prevalences of HSV-2 antibody (91% vs. 78%, P=.02), HSV-2 shedding (43% vs. 22%, P=. 003), and levels of HSV-2 DNA (P=.01) were all significantly higher among HIV-1-seropositive than among HIV-1-seronegative women. There was a significant correlation between genital HIV-1 RNA and HSV-2 DNA levels (P=.02) among the 23 women who were shedding HSV-2 DNA. If confirmed, such associations highlight the urgent need for HSV-2 control measures in populations at high risk of both infections.

Black People↗
PubMed2000

Study of vitamin E net mass transfer between alpha-tocopherol-enriched HDL and erythrocytes: application to asymptomatic hypercholesterolemic men.

We previously showed that hypercholesterolemic asymptomatic men had lower erythrocyte vitamin E content, despite normal plasma concentrations compared to normocholesterolemic men. We hypothesized that the reduced erythrocyte vitamin E concentration could be due to an impairment of transfer of vitamin E from plasma lipoproteins. We first developed a model for testing the ability of erythrocytes to accept vitamin E from high-density lipoproteins (HDL) pre-enriched in vitamin E, which allows to measure a net mass transfer of vitamin E from HDL to erythrocytes. Vitamin E-enriched HDL were obtained in controlled conditions of concentration and incubation time with a good reproducibility (CV </= 10%). The kinetic study of the net mass transfer of vitamin E to erythrocytes of healthy volunteers shows small inter- and intraindividual variations. The application of this model to erythrocytes of hyper- and normocholesterolemic men demonstrates that the reduced erythrocyte vitamin E content observed in hypercholesterolemic men was not due to a reduced ability of these cells to accept vitamin E from HDL. It might rather be due to an impairment of lipoproteins in the delivery of vitamin E to tissues, or to an oxidative stress which consumes antioxidants.

Biological Transport, Active↗
PubMed2000

Relationship between altered postprandial lipemia and insulin resistance in normolipidemic and normoglucose tolerant obese patients.

OBJECTIVE: Although there are changes in the postprandial lipid responses of obese patients, these are closely associated with high fasting triglycerides (TG). This study of 17 normotriglyceridemic, normoglucose-tolerant android obese subjects (body mass index, BMI = 34.3 +/- 3.1 kg/m2) and 33 normal-weight controls (BMI = 21.8 +/- 1.6 kg/m2) was done to examine their postprandial responses to an oral fat loading test containing retinol (890 calories, 85% fat) and to evaluate the possible association between clinical and biological features of obesity and/or insulin resistance and postprandial lipemia. SUBJECTS AND MEASUREMENTS: Blood samples were taken before giving the fat load and at 2,3,4,5,6 and 8 h after it. Insulin sensitivity was assessed using HOMA, and TG and retinyl palmitate (RP) in the plasma, chylomicrons and non-chylomicron fractions were measured each time. RESULTS: The areas under the curves (AUC) of chylomicron TG for the obese and controls were not different, indicating adequate lipolytic activity. By contrast, the AUC for non-chylomicron TG was significantly greater in the obese than in the controls (512 +/- 135 vs 429 +/- 141 mmol/lmin, P < 0.01). In addition, the AUC for RP in this same fraction was significantly lower in the obese than in the controls (103 +/- 55 vs 157 +/- 88 mg/l min, P < 0.05), suggesting that the TG from endogenous lipoproteins accounted for most of the increase in TG in the non chylomicron fraction. Parameters related to obesity showed no relationship with these postprandial abnormalities, whereas HOMA, which discriminated between the groups, partly explained (r2= 23%, P < 0.01) the significant increase in non-chylomicron TG. CONCLUSIONS: Android obese patients with a fasting TG in the normal range and not different from the fasting TG of lean controls had an abnormal postprandial lipemia response, indicated by a significantly greater TG in the non-chylomicron subfraction than in controls. These alterations may be partly due to postprandial changes in endogenous lipoproteins as a consequence of insulin resistance.

Adult↗
PubMed2000

Human ApoA-IV overexpression in transgenic mice induces cAMP-stimulated cholesterol efflux from J774 macrophages to whole serum.

The role of apolipoprotein A-IV (apoA-IV) in lipoprotein metabolism has not been established. The aim of the present study was to investigate the role of apoA-IV in reverse cholesterol transport by comparing cellular cholesterol efflux to serum or serum fractions from control mice and from mice transgenic for human apoA-IV (HuA-IVTg mice). When Fu5AH hepatoma cells were used, the cholesterol efflux to serum from either control or transgenic mice was similar. When control J774 macrophage cells were used, a comparison of efflux to serum or lipoprotein-deficient serum (LPDS) failed to demonstrate any differences between control and transgenic mice. In contrast, when the J774 cells were pretreated with cAMP, there was a stimulation of efflux to whole serum or LPDS from HuA-IVTg mice. cAMP treatment had no effect on efflux to serum or LPDS from control mice. Pretreatment of the cells with cAMP did not enhance the efflux response to high density lipoprotein isolated from HuA-IVTg mouse serum. Our results suggest that apoA-IV, unassociated with high density lipoprotein particles, is responsible for enhanced cholesterol efflux. This study illustrates the role of lipid-free apolipoproteins in mediating cellular cholesterol efflux with use of a biological fluid and is potentially of physiological relevance, especially in apolipoprotein-rich extravascular fluids.

Animals↗
PubMed2000

[Trauma of the renal pedicle in children. Report of 2 cases of late revascularization with endovascular prosthesis].

OBJECTIVE: The diagnosis of renal pedicle rupture in children is difficult and often delayed. Ultrasound alone is insufficient in the assessment of all cases of renal contusion. This often leads to nephrectomy, due to the uncertain results of a late surgical revascularization procedure. A minimally invasive endovascular approach is therefore sometimes useful. CASE REPORTS: 1st case: a 6-year-old boy was admitted to the emergency department with contusion of the right flank caused by a road accident. The immediate test for haematuria was negative. Twenty-four hours after trauma, renal duplex ultrasound was performed due to the appearance of microscopic haematuria and it demonstrated trunkal thrombosis of the right renal artery, while the initial ultrasound was normal. 2nd case: a 15-year-old girl who jumped out of a window. 48 hours after the trauma, IVU was performed because of persistent microscopic haematuria and revealed a silent kidney, while the initial ultrasound was normal. Renal arteriography showed complete dissection of the right renal artery in both cases. Stenting was performed. The postoperative course was uneventful. In the first case, follow-up duplex ultrasound revealed a modification of the echostructure of the superior pole (absence of blood supply) while the lower pole had a normal interlobular blood supply. CT scan at the 2nd month confirmed normal excretion from the lower pole. In the first case, revascularization was satisfactory on the follow-up duplex ultrasound. After 20 months of follow-up, the kidney presented a normal functional and morphological appearance. CONCLUSION: The diagnosis of renal pedicle lesions remains difficult and is based on emergency CT angiography. Treatment by vascular stenting can be performed in children. In some cases of renal artery dissection, it can constitute an alternative to surgery. However, it raises the question of the medium- and long-term repercussions of renal artery stenosis on the child's growth.

Adolescent↗
PubMed1999

Oxidative modification of high-density lipoprotein 3 induced by human polymorphonuclear neutrophils. Protective effect of pentoxifylline.

The function of high-density lipoproteins (HDLs) in reverse cholesterol transport is impaired if HDLs are subjected to oxidative stress. Polymorphonuclear neutrophils (PMNs), which have been detected in the earliest stages of atherosclerotic lesions, are one of the most likely sources of the reactive oxygen species that cause such stress. In this study, we investigated the effect of a PMN oxidative burst on HDL3. We also studied the impact on these events of pentoxifylline, a drug that regulates granulocyte function. HDL3 (370 nmol.mL-1 cholesterol-HDL) was incubated with PMNs (2 x 106. mL-1) in NaCl/Pi in the presence or absence of an iron chelate complex (10 microm Fe-nitrilotriacetic acid) at 37 degreesC for 60 min or 24 h. Phorbol myristate acetate (PMA) or formyl-methionylleucyphenylalanine (fMetLeuPhe) was used to stimulate PMNs. In iron-free NaCl/Pi medium, PMA-stimulated PMNs had a 40% lower HDL3 alpha-tocopherol content, whatever the incubation time. In NaCl/Pi medium containing iron, there was 80% less HDL3 alpha-tocopherol at 60 min, and HDL3 alpha-tocopherol had almost disappeared after 24 h. In this latter condition, the amount of thiobarbituric acid-reactive substances was significantly higher than the respective control HDL3 (P < 0.05) and oxidation of HDL3 by PMA-stimulated PMNs was associated with cross-linking of apoprotein AI, which was detected by SDS/PAGE. Similar results were obtained with fMetLeuPhe-stimulated PMN except that HDL3 alpha-tocopherol was consumed much more slowly during the first 60 min. Pretreatment of PMNs with various concentrations of pentoxifylline (0.001-20 mm) led to the concentration-dependent inhibition of oxidative modification of HDL3 induced by stimulated PMNs. The addition of 20 mm pentoxifylline in the most extreme oxidative stress conditions resulted in 70% of HDL3 alpha-tocopherol being maintained, with no formation of thiobarbituric acid-reactive substances and a lower level of apoprotein AI cross-linking. Thus HDL3 is susceptible to oxidative modifications induced by stimulated PMNs, in the presence of an exogenous source of iron. Pentoxifylline inhibited the oxidative modification of HDL3 by PMNs.

Antioxidants↗
PubMed1999

Delayed changes in postprandial lipid in young normolipidemic men after a nocturnal vitamin A oral fat load test.

The oral fat load tests (OFLT) used to study postprandial lipemia are generally conducted during the day. A nocturnal fat load test could be convenient and physiologically more appropriate. We have therefore compared the lipemic responses of 9 normolipidemic young men to OFLT given at 2200 h (nocturnal) and at 0700 h (diurnal). Triglyceride and retinyl palmitate concentrations were measured for 10 h. Peak plasma concentrations or areas under curves (AUC) for triglyceride after the diurnal and nocturnal tests were not significantly different [2.17 +/- 0.78 (diurnal) vs. 2.04 +/- 0.87 mmol/L (nocturnal) and 13.12 +/- 4.45 (diurnal) vs. 13.74 +/- 5.79 mmol/(L. h) (nocturnal)]. Peak plasma concentrations and AUC retinyl palmitate for the two tests were not different [1.71 +/- 0.69 (diurnal) vs. 1.42 +/- 0.66 mg/L (nocturnal) and 7.17 +/- 3.98 (diurnal) vs. 6.63 +/- 4.23 mg/(L. h) (nocturnal)]. The diurnal triglyceride peak occurred significantly earlier (4.3 +/- 1.2 h) than the nocturnal peak (5.8 +/- 1.7 h, P < 0.05). We have developed a model using only three sample time points to predict AUC [triglyceride at 0 h, triglyceride at average peak-time (4 h for diurnal and 6 h for nocturnal tests), and triglyceride at 10 h], thus reducing the number of blood samples. The predicted AUC was well correlated with the total AUC after nocturnal OFLT (r = 0.98, P < 0.0001). The nocturnal test appeared to be well tolerated by the subjects. The three-point simplified protocol may well be suitable for studies on large groups of subjects.

Adult↗
PubMed1998

Erythrocyte antioxidant status in asymptomatic hypercholesterolemic men.

An imbalance between antioxidant and oxidant-generating systems leading to an oxidative stress has already been proposed in the pathogenesis of atherosclerosis. In the present study we investigated the antioxidant status in 60 asymptomatic hypercholesterolemic (HC) men compared with 48 normocholesterolemic (NC) men. Hypercholesterolemic subjects had a significantly lower red blood cell vitamin E (vit E-RBC) content in spite of their normal total plasma and HDL vitamin E concentrations. Activities of erythrocyte superoxide dismutase and glutathione peroxidase were not significantly different between groups. We also determined the resistance of RBCs to an oxidative stress by determining the extent of hemolysis induced by a water-soluble azo-compound. This resistance was significantly decreased in HC men compared with NC subjects. These results demonstrate an altered antioxidant status of RBC in asymptomatic HC men associated with an increased erythrocyte susceptibility to an oxidative stress. The measure of the vitamin E content in RBC might be the most sensitive parameter for evidencing early oxidative stress which does not need an adaptation of enzymatic protective systems.

Adult↗
PubMed1998

[Synovial sarcoma localized in the muscles].

We report three cases of synovial sarcoma strictly located in the muscles. Synovial sarcoma generally arises in the vicinity of joints, tendon sheaths, bursae, fascia, and ligaments. Strictly intramuscular locations are not well known and not described in the literature to our knowledge although they seem to be frequent. The different characteristics on the radiographic examinations are non specific, and this location may be misleading. MRI is considered the procedure of choice for staging this tumor and to visualize soft tissues and bone invasion. CT scans may be useful in detecting more specific small calcifications.

Adult↗
PubMed1997

Fatty acid composition of an oral load affects chylomicron size in human subjects.

HDL-phospholipids are determinants in reverse cholesterol transport. They are mostly derived from triacylglycerol (TG)-rich lipoproteins. Chylomicron size is important, therefore, because it is related to the ratio surface phospholipids: core TG and, thus, determines the availability of postprandial phospholipids for transfer to HDL. Eleven healthy young women each ingested four different fat loads supplemented with retinyl palmitate and containing 60 g sunflower oil (SO), oleic-sunflower oil (OSO), mixed oil (MO; (g/kg) linoleic acid 480, oleic acid 380, linolenic acid 13) or beef tallow (BT). At the peak of TG absorption for all loads (4 h) chylomicron diameters, determined by agarose-gel filtration, were larger after SO compared with OSO (P < 0.05) and BT (P = 0.06) and after MO compared with BT (P < 0.05). At 6 h chylomicron size was larger after the vegetable oils compared with BT (P < 0.05 in each case). After each fat load chylomicron size decreased at 6 and 8 h compared with that at 4 h (P < 0.05) except for OSO. Retinyl ester and TG concentrations were lower in chylomicrons after BT than after the other fats but not in the chylomicron-free serum (containing chylomicron remnants), suggesting absorption in the form of very small particles. Compared with the fasting value, the concentration of the Svedberg unit of flotation 20-400 fraction, which contains VLDL and chylomicron remnants, was lower 8 h after MO, the only fat to contain significant amounts of linolenic acid. We conclude that chylomicron size is dependent on the fatty acid composition of ingested fats and the time-course of digestion, being larger for polyunsaturated fatty acid-rich fats and in the early phase of digestion. On the basis of retinyl ester concentration there were no differences between fats in chylomicron-remnant clearance.

Adult↗