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The hedgehog (hh) signaling pathway has been shown to play crucial roles in the development of embryonic gut. However, its role in intestinal development and function beyond the embryonic stage is still undefined. Expression of hh and its receptor, Patched, were examined by Western blot and X-gal staining. An anti-hh monoclonal antibody was administered into developing embryos or postnatal mice and histologic analyses were performed. Effects on lipid metabolism were examined by Oil Red O and Sudan III stainings, messenger RNA (mRNA) analysis, and electron microscopy. Serum apolipoprotein IV level, a marker for lipid absorption, was quantified by Western blot. Mice receiving anti-hh monoclonal antibody in utero or after birth exhibited progressive runting and died before weaning. Histology revealed hyperproliferation of intestinal crypt epithelial cells and disorganization of the villi with prominent vacuolation and accumulation of neutral lipid. Fecal fat microscopy revealed numerous large fat droplets. Intestinal mRNA abundance of 2 candidate genes involved in lipid transport, mtp and apob, was unchanged, although serum levels of apolipoprotein A-IV were reduced. Abnormal villus structure, lipid-filled enterocytes, and fatty stools in anti-hh monoclonal antibody-treated mice indicate a novel role for hh signaling in intestinal morphogenesis and lipid transport in postnatal mice. Show less

This article reviews the current status of our knowledge of lipoproteins, nutrition, and coronary heart disease (CHD). Special emphasis is placed on CHD risk assessment, dietary intervention studies, diet-gene interactions, and current dietary guidelines and the contributions of my laboratory to these areas. CHD remains a major cause of death and disability, and risk factors include age, sex, hypertension, smoking, diabetes, elevated serum LDL cholesterol, and low HDL cholesterol. Emerging independent risk factors include elevated serum concentrations of lipoprotein(a), remnant lipoproteins, and homocysteine. The cornerstone of CHD prevention is lifestyle modification. Dietary intervention studies support the concepts that restricting saturated fat and cholesterol and increasing the intake of essential fatty acids, especially n - 3 fatty acids, reduces CHD risk. The variability in LDL-cholesterol response to diet is large, related in part to APOE and APOA4 genotype. The use of antioxidants in intervention studies has not been shown to reduce CHD risk. Compliance with dietary recommendations remains a major problem, and directly altering the food supply may be the most effective way to ensure compliance. The available data indicate that the recommendation to use fats, oils, and sugars sparingly for CHD prevention should be modified to a recommendation to use animal, dairy, and hydrogenated fats; tropical oils; egg yolks; and sugars sparingly and to increase the use of vegetables, fruit, and whole grains. Show less

Cell culture studies and investigations in mice that overexpress either human or mouse apolipoprotein A-IV (apoA-IV) revealed anti-atherogenic properties of apoA-IV. An association between low apoA-IV concentrations and coronary artery disease in humans was demonstrated; therefore, apoA-IV may also play an antiatherogenic role in humans. Because apoA-IV is markedly elevated in dialysis patients, patients with the earliest and modest stages of renal impairment were studied to assess the association of apoA-IV with GFR and atherosclerotic complications. GFR was measured by the use of iohexol in 227 non-nephrotic patients with different degrees of renal impairment. ApoA-IV increased significantly with decreasing GFR and was already elevated in earliest stages of renal disease (GFR > 90 ml/min per 1.73 m2). Multiple linear regression analysis identified renal function parameters (GFR, creatinine, and urea) as the most important determinants of apoA-IV levels in serum of these patients. Twenty-six patients had already experienced 36 atherosclerotic events. Logistic regression analysis identified three variables associated with atherosclerotic complications: age, apoA-IV, and gender. Each 1 mg/dl increase of apoA-IV decreased the odds ratio for an atherosclerotic complication by 8% (P = 0.011). The data clearly show that the anti-atherogenic apoA-IV starts to increase during the earliest phases of renal insufficiency, which makes apoA-IV an early marker of renal impairment. Show less

We have investigated the mechanism of functional cooperativity between specificity protein 1 (Sp1) and hepatocyte nuclear factor-4 (HNF-4) on the human apolipoprotein CIII (apoCIII) promoter. Cotransfections in Drosophila SL2 cells that lack endogenous Sp1 or Sp1-related activities showed that HNF-4 and Sp1 synergistically transactivate the -890/+24 apoCIII promoter up to 150-fold. Synergistic transactivation required the HNF-4 binding site of the apoCIII enhancer. Deletion of part of the Ser/Thr-rich and Gln-rich domain or the C-terminal domain of Sp1 decreased, and deletion of residues 501-610 of Sp1 increased, the functional cooperativity between Sp1 and HNF-4. Physical interactions between the two factors were demonstrated by glutathione S-transferase pull-down and co-immunoprecipitation assays. The amino terminal domain of both factors and the carboxy terminal domain of Sp1 contribute to these interactions. Antagonism between HNF-4 and Sp1 was demonstrated on homopolymeric promoters containing multiple binding sites for either factor, suggesting that the synergism between the two factors occurs only when both factors are bound simultaneously to the DNA. The observed physical interactions between Sp1 and HNF-4 in the context of the apoCIII promoter may explain in part their in vitro and in vivo synergism in the transcriptional activation of the apolipoprotein A-I/apoCIII/apolipoprotein A-IV gene cluster. Show less

Lipid, particularly long-chain triglyceride, initiates feedback regulation of gastrointestinal function. To determine whether the site of action of lipid is pre- or postabsorptive, we investigated the ability of mesenteric lipid-fed lymph to inhibit gastric motor function. Lymph was collected from awake lymph-fistula rats during intestinal infusion with either a glucose-saline maintenance solution or lipid. Intra-arterial injection of lymph collected during intestinal lipid infusion significantly inhibited gastric motility in anesthetized recipient rats compared with injection of equivalent amounts of triglyceride or lymph collected during intestinal infusion of maintenance solution. Lymph collected from rats during lipid infusion with Pluronic L-81 [an inhibitor of chylomicron formation and apolipoprotein (apo) A-IV secretion] compared with lymph injection from donor animals treated with Pluronic L-63 (a noninhibitory control for Pluronic L-81) was significantly less potent. Injection of purified recombinant apo A-IV significantly inhibited gastric motility. Products of lipid digestion and absorption, other than fatty acids or triglyceride, released by the intestine during lipid digestion likely serve as signals to initiate intestinal feedback regulation of gastrointestinal function. Most likely, apo A-IV is one of the signals involved. Show less

While human diets have markedly evolved since their origin, the human genome has only marginally changed. Nevertheless, polymorphisms of common genes are widespread. It has been substantiated that most major diseases (including cardiovascular disease, diabetes, obesity and cancers) result from the interaction between genetic susceptibility and environmental factors, including diet. In the field of lipoprotein metabolism and cardiovascular disease several gene polymorphisms for key proteins, such as apoproteins (apo) E, B, A-IV and C-III, LDL receptor, microsomal transfer protein (MTP), fatty acid-binding protein (FABP), cholesteryl ester transfer protein (CETP), lipoprotein lipase and hepatic lipase, have been identified and linked to variable responses to diets. We are carrying out an intervention study (RIVAGE) in Marseille dedicated to investigating the interactions between diets (Mediterranean or low-fat types v. standard Western type), risk factors for cardiovascular disease and gene polymorphisms in about 300 patients randomized into two groups over periods of 3 and 12 months. Some data obtained in about 100 patients after 3 months of dietary change are available. Among single nucleotide polymorphisms (SNP) already studied (apoE (epsilon2, epsilon3, epsilon4), apoB (-516C/T), apoC-III (SstI), apoA-IV (Ser347Thr), MTP (-493G/T), intestinal FABP (Ala54Thr), CETP (TaqIB) and hepatic lipase (-480C/T)), some SNP showed interactions with diets in relation to changes in particular variables after 3 months on the dietary regimens. This was the case for apoE and LDL-cholesterol and triacylglycerols, apoA-IV and LDL-cholesterol, MTP and LDL-cholesterol, intestinal FABP and triacylglycerols. These data provide evidence of the interaction between some SNP and the metabolic response to diets. Show less

Apolipoprotein A-IV (apo A-IV) is a glycoprotein synthesized by the human intestine. In rodents, both the small intestine and liver secrete apo A-IV, but the small intestine is the major organ responsible for the circulating apo A-IV. Intestinal apo A-IV synthesis is markedly stimulated by fat absorption and appears not to be mediated by the uptake or reesterification of fatty acids to form triglycerides. Rather, the formation of chylomicrons acts as a signal for the induction of intestinal apo A-IV synthesis. Intestinal apo A-IV synthesis is also enhanced by a factor from the ileum, probably peptide tyrosine-tyrosine. The inhibition of food intake by apo A-IV is mediated centrally. The stimulation of intestinal synthesis and the secretion of apo A-IV by lipid absorption are rapid; thus, apo A-IV likely plays a role in the short-term regulation of food intake. Other evidence suggests that apo A-IV may also be involved in the long-term regulation of food intake and body weight. Chronic ingestion of a high-fat diet blunts the intestinal apo A-IV response to lipid feeding and may explain why the chronic ingestion of a high-fat diet predisposes both animals and humans to obesity. Show less

Apolipoprotein AIV (apo AIV) is a satiety protein secreted by the small intestine. We demonstrate for the first time that apo AIV protein and apo AIV mRNA are present in rat hypothalamus, a site intimately involved in the integration of signals for regulation of food intake and energy metabolism. We further characterized the regulation of hypothalamic apo AIV mRNA levels. Food-deprived animals showed a pronounced decrease in gene expression of apo AIV in the hypothalamus, with a concomitant decrease in the jejunum. Refeeding fasted rats with standard laboratory chow for 4 h evokes a significant increase of apo AIV mRNA in jejunum but not in hypothalamus. However, lipid refeeding to the fasted animals restored apo AIV mRNA levels both in hypothalamus and jejunum. Intracerebroventricular administration of apo AIV antiserum not only stimulated feeding, but also decreased apo AIV mRNA level in the hypothalamus. These data further confirm the central role of apo AIV in the regulation of food intake. Show less

To evaluate the relationship between plasma apoA-IV levels and coronary atherosclerosis and to explore its relation to other risk factors. Using ELISA techniques, plasma apoA-IV levels were quantified in 181 patients who underwent coronary angiography (CAG). Patients were divided according to their coronary status into a coronary heart disease (CHD) group (stenotic lesion on CAG, n = 118) and a control group (normal CAG, n = 63). The severity of atherosclerosis was assessed by stenosis scoring of the different lesions. Other parameters, including apoA-I, apoB, Lp(a), HDL-C, LDL-C, TG, and TC, were measured as well. Univariate, logistic regression analyses were used to define the relationship between coronary atherosclerosis and plasma apoA-IV levels. When compared with the control group, plasma apoA-IV levels were found to be lower in the CHD group. There was a weak negative correlation between plasma apoA-IV levels and the severity of coronary atherosclerosis. ApoA-IV was found to be a relatively independent risk factor for CHD. We also found a positive correlation between apoA-IV and triglyceride levels. ApoA-IV may be important in the prediction of CHD and coronary atherosclerosis severity. It may also play an important role in the metabolism of triglycerides. Show less

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is abundant in serum and associates with high density lipoproteins (HDL). We have characterized the distribution of GPI-PLD among lipoproteins in human plasma. Apolipoprotein (apo)-specific lipoproteins containing apoB (Lp[B]), apoA-I and A-II (Lp[A-I, A-II]), or apoA-I only (Lp[A-I]) were isolated using dextran sulfate and immunoaffinity chromatography. In six human plasma samples with HDL cholesterol ranging from 39 to 129 mg/dl, 79 +/- 14% (mean +/- SD) of the total plasma GPI-PLD activity was associated with Lp[A-I], 9 +/- 12% with Lp[A-I, A-II], and 1 +/- 1% with Lp[B]; and 11 +/- 10% was present in plasma devoid of these lipoproteins. Further characterization of the GPI-PLD-containing lipoproteins by gel-filtration chromatography and nondenaturing polyacrylamide and agarose gel electrophoresis revealed that these apoA-I-containing particles/complexes were small (8 nm) and migrated with pre-beta particles on agarose electrophoresis. Immunoprecipitation of GPI-PLD with a monoclonal antibody to GPI-PLD co-precipitated apoA-I and apoA-IV but little or no apoA-II, apoC-II, apoC-III, apoD, or apoE. In vitro, apoA-I but not apoA-IV or bovine serum albumin interacted directly with GPI-PLD, but did not stimulate GPI-PLD-mediated cleavage of a cell surface GPI-anchored protein. Thus, the majority of plasma GPI-PLD appears to be specifically associated with a small, discrete, and minor fraction of lipoproteins containing apoA-I and apoA-IV. -- Deeg, M. A., E. L. Bierman, and M. C. Cheung. GPI-specific phospholipase D associates with an apoA-I- and apoA-IV-containing complex. J. Lipid Res. 2001. 42: 442--451. Show less

We determined apolipoprotein AIV (apo AIV) content in intestinal epithelial cells using immunohistochemistry when leptin was administered intravenously. Most of the apo AIV immunoreactivity in the untreated intestine was located in the villous cells as opposed to the crypt cells. Regional distribution of apo AIV immunostaining revealed low apo AIV content in the duodenum and high content in the jejunum that gradually decreases caudally toward the ileum. Intraduodenal infusion of lipid (4 h) significantly increased apo AIV immunoreactivity in the jejunum and ileum. Simultaneous intravenous leptin infusion plus duodenal lipid infusion markedly suppressed apo AIV immunoreactivity. Duodenal lipid infusion increased plasma apo AIV significantly (measured by ELISA), whereas simultaneous leptin infusion attenuated the increase. These findings suggest that leptin may regulate circulating apo AIV by suppressing apo AIV synthesis in the small intestine. Show less

Apolipoprotein (apo)A-IV is synthesized in the small intestine during fat absorption and is incorporated onto the surface of nascent chylomicrons. In circulation, apoA-IV is displaced from the chylomicron surface by high density lipoprotein-associated C and E apolipoproteins; this exchange is critical for activation of lipoprotein lipase and chylomicron remnant clearance. The variant allele A-IV-2 encodes a Q360H polymorphism that increases the lipid affinity of the apoA-IV-2 isoprotein. We hypothesized that this would impede the transfer of C and E apolipoproteins to chylomicrons, and thereby delay the clearance of postprandial triglyceride-rich lipoproteins. We therefore measured triglycerides in plasma, S(f) > 400 chylomicrons, and very low density lipoproteins (VLDL) in 14 subjects heterozygous for the A-IV-2 allele (1/2) and 14 subjects homozygous for the common allele (1/1) who were fed a standard meal containing 50 gm fat per m(2) body surface area. All subjects had the apoE-3/3 genotype. Postprandial triglyceride concentrations in the 1/2 subjects were significantly higher between 2;-5 h in plasma, chylomicrons, and VLDL, and peaked at 3 h versus 2 h for the 1/1 subjects. The area under the triglyceride time curves was greater in the 1/2 subjects (plasma, P = 0.045; chylomicrons, P = 0.027; VLDL, P = 0.063). A post-hoc analysis of the frequency of the apoA-IV T347S polymorphism suggested that it had an effect on triglyceride clearance antagonistic to that of the A-IV-2 allele. We conclude that individuals heterozygous for the A-IV-2 allele display delayed postprandial clearance of triglyceride-rich lipoproteins. Show less

Research in the field of gene-diet interactions as determinants of plasma lipid response to dietary interventions has accumulated a substantial body of evidence during the past decade. Several candidate genes have shown some promise as potential markers of individual dietary responsiveness. Among the best characterized are the APOE, APOA4, APOB, APOC3, and LPL loci. Other genes are being continuously incorporated to this most interesting search. However, in very few cases has consensus been achieved about the usefulness of genetic markers as clinically significant predictors of dietary response. The increased ability to generate genotypic information, in combination with the knowledge from the human genome project and more comprehensive experimental designs, will dramatically improve our capacity to answer many of our current questions. It will also help to prove that knowledge of an individual's genetic background will facilitate more precise dietary counseling and intervention, and more efficacious primary and secondary coronary heart disease prevention. Show less

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. Show less

To assess the effect of glutamine availability on rates of protein synthesis in human enterocytes, Caco-2 cells were grown until differentiation and then submitted to glutamine deprivation produced by exposure to glutamine-free medium or methionine sulfoximine [L-S-[3-amino-3-carboxypropyl]-S-methylsulfoximine (MSO)], a glutamine synthetase inhibitor. Cells were then incubated with (2)H(3)-labeled leucine with or without glutamine, and the fractional synthesis rate (FSR) of total cell protein was determined from (2)H(3)-labeled enrichments in protein-bound and intracellular free leucine measured by gas chromatography-mass spectrometry. Both protein FSR (28 +/- 1.5%/day) and intracellular glutamine concentration (6.1 +/- 0.6 micromol/g protein) remained unaltered when cells were grown in glutamine-free medium. In contrast, MSO treatment resulted in a dramatic reduction in protein synthesis (4.6 +/- 0.6 vs. 20.2 +/- 0.8%/day, P < 0.01). Supplementation with 0.5-2 mM glutamine for 4 h after MSO incubation, but not with glycine nor glutamate, restored protein FSR to control values (24 +/- 1%/day). These results demonstrate that in Caco-2 cells, 1) de novo glutamine synthesis is highly active, since it can maintain intracellular glutamine pool during glutamine deprivation, 2) inhibition of glutamine synthesis is associated with reduced protein synthesis, and 3) when glutamine synthesis is depressed, exogenous glutamine restores normal intestinal FSR. Due to the limitations intrinsic to the use of a cell line as an experimental model, the physiological relevance of these findings for the human intestine in vivo remains to be determined. Show less

To search the variation of apoA IV gene and its relation to endogenous hypertriglyceridemia (HTG) in Chinese population. Forty- seven endogenous hypertriglyceridemics and 48 healthy subjects from a population of Chinese Han nationality in Chengdu area were studied using sequencing of apoA IV gene amplified by polymerase chain reaction (PCR). The frequency of (CTGT)(3) allele in Chinese control group was significantly different from that reported in German Caucasians (0.253 vs 0.607, P<0.01) and in Italian Caucasians (0.253 vs 0.522, P<0.01), but not different from that reported in Japanese (0.253 vs 0.262, P>0.05). The frequency of (CTGT)(3) allele showed no significant difference between normal control and HTG groups(0.223 vs 0.281,P>0.05). In the healthy control group, the subjects with genotype 3/3 of VNTR site had a higher serum mean concentration of LDLC as compared to those with genotype 3/4 (3.698 +/- 0.67 mmol/L vs 2.974 +/- 0.54 mmol/L, P<0.05). The results suggest that VNTR polymorphism in apoA IV gene is associated with healthy control subjects to some extent in Chinese population. Show less

We examined the effect of daily fat supplementation on intestinal gene expression and protein synthesis and plasma levels of apolipoprotein A-IV (apo A-IV). Rats were fasted overnight and then given intragastric bolus infusion of either saline or fat emulsion after 0, 1, 2, 4, 8, or 16 days of similar daily feedings. Four hours after the final saline or fat infusion, plasma and jejunal mucosa were harvested; plasma levels of apo A-IV, triglycerides, and leptin were measured, as well as mucosal apo A-IV mRNA levels and biosynthesis of apo A-IV protein. In response to fat, plasma apo A-IV showed an initial 40% increase compared with saline-injected control rats; with continued daily fat feeding, the plasma A-IV response showed rapid and progressive diminution such that by 4 days, plasma A-IV was not different between fat- and saline-fed groups. Jejunal mucosal apo A-IV synthesis and mRNA levels also showed time-dependent refractoriness to fat feeding. However, the kinetics of this effect were considerably slower than in the case of plasma, requiring 16 days for completion. There was no correlation between plasma leptin or triglyceride levels and intestinal apo A-IV synthesis or plasma apo A-IV. These results indicate rapid, fat-induced, posttranslational adapation of plasma apo A-IV levels and a slower, but similarly complete pretranslational adaptation of intestinal apo A-IV production, which are independent of plasma levels of leptin. Show less

Linkage and association of the apo AI-CIII-IV gene region to familial combined hyperlipidemia (FCHL) was reported previously, based on the presence of genetic variants in the apo CIII and apo AI gene. No data were available yet on the contribution of the apo A-IV locus. Two DNA variants in exon 3 of the apo A-IV gene, A (Thr)(347)T (Ser) and [CTGT](3-4) were characterized by sequencing the coding region of the apo A-IV gene and were analyzed in our Dutch FCHL cohort (30 probands, 159 affected relative, 317 unaffected relatives and 218 spouses). The genotype frequency of the A(347)T variant was different in probands and spouses. In probands no 2/2 carriers were found, resulting in a significant decreased frequency of the 2-allele (P<0.05). This was suggestive for a protective role of the presence of the serine (T) allele on the prevalence of FCHL. No difference in frequency distribution was found for the [CTGT](3-4) variant between the groups. Homozygous 4/4 carriers in spouses had a more favorable lipid profile (LDL-cholesterol and apo B, P<0.05). The absence of linkage disequilibrium of the A(347)T with other markers in the gene cluster, and the absence of linkage disequilibrium with [CTGT](3-4) marker and the MspI-AI marker in the apo A-I promoter showed that these two apo A-IV variants reside on different haplotypes from the apo A-I and apo C-III markers. This was illustrated by extensive haplotype analysis. The present data on the contribution of DNA variants in the apo A-IV gene support our previous observations that the apo AI-CIII-AIV gene cluster has a complex genetic contribution to FCHL both by conferring susceptibility and protection. Show less

By supplying most organs of the body with metabolic substrates, the liver plays a central role in maintaining energy balance. Hepatic metabolism of glucose, fatty acids, and lipoproteins is disrupted in the leptin-deficient obese (Lep(ob)/Lep(ob)) mouse, leading to hyperglycemia, steatosis, and hypercholesterolemia. Microarray expression profiles were used to identify transcriptional perturbations that underlie the altered hepatic physiology of Lep(ob)/Lep(ob) mice. A wide variety of genes involved in fatty acid metabolism are altered in expression, which suggests that both fatty acid synthesis and oxidation programs are activated in obese mice. The expression of a small subset of genes is upregulated by leptin deficiency, not modulated by caloric restriction, and markedly suppressed by short-term leptin treatment. Among these leptin-regulated genes, apolipoprotein A-IV is a strong candidate for mediating the atherogenic-resistant phenotype of Lep(ob)/Lep(ob) mice. Show less

The aim of this study was to determine: (1) whether the Short Chain Fatty Acids (SCFA) Acetate, Propionate, and Butyrate enhance the synthesis and secretion of intestinal apolipoprotein A-IV-containing lipoproteins and (2) if so, whether these particles are able to promote cholesterol efflux in vitro. For this purpose Caco-2 cells were used for their functional properties of differentiated enterocytes. They were incubated with the three SCFA (2, 4, and 8 mM) for 48 h. Only butyrate stimulated apoA-IV gene expression and this was associated with an increase in apoA-IV secretion. A nondenaturing 2D-PAGE (agarose gel was followed by PAGE) was used to identify apoA-IV-containing lipoproteins in various media, and showed that butyrate stimulated the secretion of two small HDL sized particles. The influence of these secreted particles on cholesterol efflux was investigated using incubation of media with (3)H-cholesterol-labeled Fu5AH cells. The data indicate that conditioned media from Caco-2 cells treated with butyrate resulted in an increase of 20-30% in cholesterol efflux. We conclude that butyrate may regulate apoA-IV secretion and, therefore, modulate reverse cholesterol transport. Show less

The in vivo organ distribution of particulate drug carriers is decisively influenced by the interaction with plasma proteins after i.v. administration. Serum protein adsorption on lipid drug conjugate nanoparticles, a new carrier system for i.v. application, was investigated by 2-dimensional electrophoresis (2-DE). The particles were surface-modified to target them to the brain. To assess the protein adsorption pattern after i.v. injection in mice prior to in vivo studies, the particles were incubated in mouse serum. Incubation in human serum was carried out in parallel to investigate similarities or differences in the protein patterns obtained from men and mice. Distinct differences were found. Particles incubated in human serum showed preferential adsorption of apolipoproteins A-I, A-IV and E. Previously, preferential adsorption of ApoE was reported as one important factor for targeting of Tween(R)80 modified polybutylcyanoacrylate nanoparticles to the brain. Preferential adsorption of ApoA-I and A-IV took place after incubation in mouse serum, adsorption of ApoE could not be clearly confirmed. In vivo localization of the LDC nanoparticles at the blood-brain barrier and diffusion of the marker Nile Red into the brain could be shown by confocal laser-scanning microscopy. Differences of the obtained adsorption patterns are discussed with regard to their relevance for correlations of in vitro and in vivo data obtained from different species. Show less

The metabolism of apolipoprotein (apo) A-IV in diabetes mellitus (DM) is poorly understood. Several factors, such as dietary fat intake, fat malabsorption, acute inflammation, and hormonal dysregulation can disturb the plasma apo A-IV concentration. We have compared the plasma apo A-IV concentrations in patients with type 1 DM and DM secondary to chronic pancreatitis to determine the effects of combinations of these factors. We examined 4 groups of male patients with chronic pancreatitis without diabetes (ND-CP) (n = 12), diabetes secondary to chronic pancreatitis and insulin-treated (CP-DM) (n = 32), type 1 diabetes (n = 25), and controls (n = 20). Plasma apo A-IV was significantly lower in the chronic pancreatitis patients (ND-CP and CP-DM) than in the other patients. Inflammatory proteins (fibrinogen, ceruloplasmin, and haptoglobin) were significantly elevated in the 2 chronic pancreatitis groups. The apo A-IV concentration was positively correlated with hemoglobin A(1c) (HbA(1c)) percentage in each group of diabetic patients (CP-DM, r =.35; P =.046; type 1 DM, r =.53; P =.010), in both groups of diabetic patients (r =.472; P <.0001) and negatively correlated with ceruloplasmin concentration in each group of diabetic patients (CP-DM, r = -.48; P =.0052; type 1 DM, r = -.66; P =.003), in both groups of diabetic patients (r = -.561; P <.0001), and in the whole population (r = -.463; P <.0001). Apo A-IV was also negatively correlated with haptoglobin in type 1 DM patients (r = -.434; P =.0435), in the both groups of diabetic patients (r = -.349; P =.0154), and in the whole population (r = -.351; P =.0019). Multiple linear regression analysis revealed that only HbA(1c) and ceruloplasmin were independent explanatory variables. Plasma apo A-IV is positively correlated with HbA(1c) suggesting that hyperglycemia per se selectively affects apo A-IV metabolism. The correlation between the concentrations of inflammatory protein and apo A-IV suggest a link between chronic inflammation and apo A-IV synthesis or catabolism. As apo A-IV is involved in reverse cholesterol transport, its low level in CP-DM may contribute to the accelerated development of atherosclerosis in these patients. Show less

Apolipoprotein (apo) A-IV is a major component of triacylglycerol-rich lipoprotein (TRL) apolipoproteins. We investigated the effects of dietary saturated fat and cholesterol restriction on the metabolism of TRL and plasma apo A-IV. We assessed TRL and plasma apo A-IV kinetics in 16 and 4 subjects, respectively, consuming an average US (baseline) diet for 6 wk and a National Cholesterol Education Program Step II diet for 24 wk, respectively. At the end of each diet period, all subjects received a primed, constant infusion of deuterated leucine for 15 h with hourly feeding. Ratios of stable-isotope tracer to tracee were measured by using gas chromatography-mass spectrometry, and kinetic data were modeled by using SAAM II. Mean apo A-IV concentrations during the isotope infusion period were 6.9 +/- 2.6 mg/L in TRL and 2.2 +/- 3.2 mg/L in plasma with the baseline diet; these values were 37.7% (P < 0.001) and 19.4% (P < 0.01) lower with the Step II diet. Similar changes were observed in the fasting state between the 2 diets. The mean apo A-IV secretion rate decreased significantly from baseline by 59.6% in TRLs and by 40.2% in plasma. Significant correlations were observed between TRL apo A-IV concentrations and the secretion rate (r = 0.94, P < 0.001) and between TRL apo A-IV pool size and TRL-cholesterol concentrations (r = 0.48, P < 0.01). Our data indicate that the National Cholesterol Education Program Step II diet significantly decreases TRL and plasma apo A-IV concentrations compared with the average US diet and that this decrease is due to a decreased secretion rate. Show less

Phospholipid (PL) from both dietary sources and biliary secretions may be important in the regulation of intestinal apolipoprotein (apo) synthesis. We previously demonstrated the up-regulation of apo A-I secretion by phosphatidylcholine (PC) in a newborn piglet intestinal epithelial cell line. We hypothesized that dietary PC increases small intestinal apo A-I synthesis in vivo in the newborn piglet. Two-day-old female swine were fed by gavage for 48 h. Diets consisted of a formula containing 51% of calories as triacylglycerol providing 180 kcal/kg/24 h. The experimental group (+PC, n = 7) received 1 g/L added soybean PC, and the control group (-PC, n = 7) received no added PC. At the end of the study period, jejunal apo A-I, B, and A-IV synthesis was measured, and apo A-I mRNA levels were quantitated. Jejunal mucosal PL content and serum lipids and apo B and A-I levels were measured. Jejunal apo A-I synthesis was almost twice as high in the +PC group as compared to the -PC group with no difference in apo A-I mRNA levels. Jejunal content of PL was higher in the +PC group than in the -PC group. There were no differences in jejunal apo B and A-IV synthesis or serum levels of lipids and apo-lipoproteins between the two groups. Dietary PC supplementation in newborn swine up-regulated jejunal apo A-I synthesis. Apo A-IV synthesis, which is sensitive to fatty acid flux, was not significantly increased, which suggests a specific effect of PC on apo A-I synthesis. Lumenal PC may be important in the regulation of intestinal apo A-I synthesis in the neonate. Show less

We have previously generated transgenic (Tg) mice expressing the human apolipoprotein (apo) A-I/C-III/A-IV gene cluster. This expression induced hyperlipidemia but reduced atherosclerotic lesions in genetically modified mice lacking apoE. Atherosclerosis is a multifactorial process and environmental factors such as diet play significant roles in its development. We examined here how an atherogenic diet influences the expression of the human genes and the characteristics of the Tg mice. Our results indicate that a high fat-high cholesterol diet up-regulates the intestinal expression of the three genes and the concentration of the three proteins in plasma. Cholesterol concentration was highly increased in the non-high density lipoprotein (HDL) fraction, and less, although significantly, in the HDL fraction. Tgs showed a 65% reduction in diet-induced aortic lesions compared with non-Tg mice. Atherogenic diet increases the expression of the genes encoding the scavenger receptor class B type I (SR-BI) and ATP binding cassette transporter 1 (ABCA1) proteins. As cholesterol efflux mediated by SR-BI or by ABCA1 was enhanced in Tg mice fed an atherogenic diet, we can hypothesize that increased reverse cholesterol transport is the basis of the protective mechanism observed in these animals. In conclusion, we present evidence that the expression of the human gene cluster in mice protects against atherogenesis in response to an atherogenic diet. Show less

To determine the prevalence of non-fatal coronary artery disease (CAD) in kindred with Familial Combined Hyperlipidemia (FCHL) in relation to various cardiovascular risk factors and DNA variation in the apo AI-CIII-AIV gene cluster. Data were collected from 18 Dutch FCHL probands, 202 living first and second degree relatives, and 175 spouses. Probands and first degree relatives showed dyslipidemia, increased plasma insulin and glucose concentrations, higher waist--hip ratio (WHR), and blood pressure, than spouses. The frequency of the minor alleles M2 and S2 was increased in probands and first degree relatives. The Odds Ratio for CAD was 5.3 in male FCHL relatives (P=0.005), and 5.1 in all FCHL relatives (P=0.001). First and second degree relatives had a markedly reduced CAD-free life-span (logrank vs. spouses: P<0.001 and P=0.03, respectively). The presence of the S2, but not M2, minor allele, showed a marked reduction in CAD-free life-span (logrank S2 present vs. S2 absent: P=0.035). Men with FCHL have a severely increased risk of CAD, that appears to be mediated through genetic relation to the proband as the strongest independent risk factor for CAD, followed by increased WHR. Show less

Protein material was extracted from amyloid-rich sections of formalin-fixed and paraffin-embedded heart tissue from an individual with senile systemic amyloidosis, known to contain wild-type transthyretin as major amyloid fibril protein. Amino acid sequence analysis of tryptic peptides of this material revealed in addition to transthyretin sequences, also amino acid sequence corresponding to an N-terminal fragment of apolipoprotein A-IV. In immunohistochemistry, an antiserum to a synthetic apolipoprotein A-IV peptide labeled amyloid specifically. This peptide formed spontaneously amyloid-like fibrils in vitro and enhanced fibril formation from wild-type transthyretin. We conclude that several apolipoproteins, including apolipoprotein A-IV, may be important minor amyloid constituents, promoting fibril formation. Show less

It has been shown that a number of candidate gene loci (APOA1, APOA4, APOC3, APOB, APOE, CETP, LPL and FABP2) explain a significant, although still rather small, proportion of interindividual variability in fasting dietary responses. Other loci code for products that play a major role in lipoprotein metabolism and are prime candidate for future studies (i.e., CYP7, ABCA1, SRBI). Some of these loci also affect postprandial lipemic responses, and the interactions between genetic and dietary factors may be further modulated by body mass index. The deleterious phenotypic associations observed with some of the genotypes of candidate genes may therefore only be expressed in subjects with a high BMI. This question requires more careful research, the findings of which may contribute towards the drafting of specific dietary recommendations for the primary and secondary prevention of coronary heart disease. Show less