The composition and structure of lymph chylomicrons in dog, rat, and man.

Zilversmit, D. B.

doi:10.1172/jci105267

Cited by 206 publications

(94 citation statements)

References 29 publications

(22 reference statements)

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“…Studies by Zilversmit (27) have shown that of the free cholesterol in lymph a greater percentage is in chylomicrons, as compared to the other lipoprotein fractions of lymph. This difference is most marked in the chylomicron surface coat, the cholesterol of which is entirely in the free form.…”

Section: Discussionmentioning

confidence: 99%

Effect of mixed micellar lipid on the absorption of cholesterol and vitamin D3 into lymph

Thompson¹,

Ockner²,

Isselbacher³

1969

J. Clin. Invest.

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A B S T R A C T The absorption of endogenous cholesterol, labeled with tracer doses of cholesterol 14C or cholesterol-'H and of near physiological doses of vitamin D3-'H was studied in rats with cannulated intestinal lymphatics. The effects of administering mixed micellar solutions of fatty acid, monoglyceride, and bile salt on the absorption of these labeled sterols was determined. It was observed that the specific activity of free cholesterol and the amounts of vitamin D3 appearing in lymph were significantly increased during the intraduodenal administration of mixed micellar solutions of either linoleic or palmitic acid, in contrast to control rats receiving a micellar solution of taurocholate. These increases were related linearly to the lymph triglyceride level. In addition it was observed that when the linoleic acid solution was administered there was a more marked increase in the ratio of the specific activities of free and esterified cholesterol in lymph than with either the palmitic acid or taurocholate solutions.Additional studies in rats with intact lymphatics showed that the uptake of labeled cholesterol and vitamin D3 from the intestinal lumen into the wall was similar whether the sterols were administered in taurocholate or in mixed micellar solution.These findings suggest that mixed micellar lipid increased the rate of appearance of labeled free cholesterol and vitamin Ds in lymph by enhancing their transport out of the intestinal mucosa, rather than by an effect on uptake. INTRODUCTIONCholesterol and vitamin D3 are sterols of similar mo-

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Section: Discussionmentioning

confidence: 99%

Effect of mixed micellar lipid on the absorption of cholesterol and vitamin D3 into lymph

Thompson¹,

Ockner²,

Isselbacher³

1969

J. Clin. Invest.

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“…Chylomicrons are primarily very large, spherical TAG-rich particles (5,58) that also contain PLs, cholesterol, vitamin E, vitamin A, and protein. The lipoprotein core contains TAG, cholesteryl esters, and fat-soluble vitamins, whereas the surface contains a monolayer of PLs (mainly phosphatidylcholine), free cholesterol, and protein (127,204,205). A key structural component of the chylomicron is the huge, hydrophobic, nonexchangeable protein apoB48.…”

Section: Assembly Secretion and Regulation Of Intestinal Lipoproteinsmentioning

confidence: 99%

Intestinal lipid absorption

Iqbal¹,

Hussain²

2009

American Journal of Physiology-Endocrinology and Metabolism

648

484

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Our knowledge of the uptake and transport of dietary fat and fat-soluble vitamins has advanced considerably. Researchers have identified several new mechanisms by which lipids are taken up by enterocytes and packaged as chylomicrons for export into the lymphatic system or clarified the actions of mechanisms previously known to participate in these processes. Fatty acids are taken up by enterocytes involving protein-mediated as well as proteinindependent processes. Net cholesterol uptake depends on the competing activities of NPC1L1, ABCG5, and ABCG8 present in the apical membrane. We have considerably more detailed information about the uptake of products of lipid hydrolysis, the active transport systems by which they reach the endoplasmic reticulum, the mechanisms by which they are resynthesized into neutral lipids and utilized within the endoplasmic reticulum to form lipoproteins, and the mechanisms by which lipoproteins are secreted from the basolateral side of the enterocyte. apoB and MTP are known to be central to the efficient assembly and secretion of lipoproteins. In recent studies, investigators found that cholesterol, phospholipids, and vitamin E can also be secreted from enterocytes as components of high-density apoB-free/apoAI-containing lipoproteins. Several of these advances will probably be investigated further for their potential as targets for the development of drugs that can suppress cholesterol absorption, thereby reducing the risk of hypercholesterolemia and cardiovascular disease.intestine; dietary fat; triacylglycerol; cholesterol; phospholipids; fat-soluble vitamins; microsomal triglyceride transfer protein DIETARY FATS CONSIST OF A WIDE ARRAY of polar and nonpolar lipids (32, 33). Triacylglycerol (TAG) is the dominant fat in the diet, contributing 90 -95% of the total energy derived from dietary fat. Dietary fats also include phospholipids (PLs), sterols (e.g., cholesterol), and many other lipids (e.g., fatsoluble vitamins). The predominant PL in the intestinal lumen is phosphatidylcholine (PC), which is derived mostly from bile (10 -20 g/day in humans) but also from the diet (ϳ1-2 g/day). The predominant dietary sterols are cholesterol (mostly of animal origin) and ␤-sitosterol (the major plant sterol). Although ␤-sitosterol accounts for 25% of dietary sterols, it is not absorbed by humans under physiological conditions.Researchers have been investigating the various steps involved in lipid digestion, absorption, and metabolism to identify factors that could serve as targets for the development of drugs capable of reducing the risk of lipid-associated disorders, including dyslipidemias and cardiovascular disease. In so doing, they have explored key aspects of lipid digestion hydrolysis, emulsification, and micelle formation. They have also explored key issues of absorption, e.g., the uptake of the products of lipid hydrolysis by enterocytes (the epithelial cells lining the walls of the intestinal lumen) and their transport to intracellular compartments, where fatty acids and sterols are...

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“…During fasting, very low-density lipoproteins (VLDLs) are the only lipoproteins produced by the small intestine [87,88,114]. Following a meal, the small intestine produces predominantly CMs [114,135]. CM particles are much bigger than VLDLs and therefore carry significantly more Triglycerides (TGs) than VLDLs.…”

Section: Formation Of Intestinal Chylomicrons and Very Low-density LImentioning

confidence: 99%

Cholesterol: from feeding to gene regulation

Martini

Pallottini

2007

Genes Nutr

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We present here a brief description of the path that cholesterol covers from its intestinal absorption to its effects exerted on gene regulation. In particular, the relationship between cholesterol and the protein complexes involved in the intricate gene regulation mechanism implicated in cholesterol homeostasis will be discussed. In addition, a new target role for the pharmacological interventions of one of these factors, the insulin-induced gene (Insig) protein, will be introduced.

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The composition and structure of lymph chylomicrons in dog, rat, and man.

Cited by 206 publications

References 29 publications

Effect of mixed micellar lipid on the absorption of cholesterol and vitamin D3 into lymph

Effect of mixed micellar lipid on the absorption of cholesterol and vitamin D3 into lymph

Intestinal lipid absorption

Cholesterol: from feeding to gene regulation

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