Liver cholesterol

In the liver, cholesterol and triglycerides are incorporated into VLDL along with phospholipids and apolipoprotein B-100... 

Hayden et al. 1990a), increased liver cholesterol in female rats exposed during gestation and lactation (Hayden et al. 1990b), and weight loss in pregnant rats (Saillenfait et al. 1989). 

TABLE 4.1 Effect of dietary psyllium on plasma and liver cholesterol concentrations in hamsters°... 

Number per group Days on diet Cholesterol in diet (%) Psyllium in diet (%) Fat in diet (%) Plasma cholesterol (mmol/l) Decrease (%) Liver cholesterol (pmol/g) Decrease (%) References... 

Terpstra, A. H. M., Lapre, J. A., de Vries, H. T., and Beynen, A. C. (1998). Dietary pectin with high viscosity lowers plasma and liver cholesterol concentration and plasma cholesteryl ester transfer protein activity in hamsters. /. Nutr. 128,1944-1949. 

CNIOI Van Lith, H. A., M. Haller, G. Van Tintelen, A. G. Lemmens, L. E. Van Zutphen, and A. C. Beynen. Eat intake and clofibrate administration have interrelated effects on liver cholesterol concentration and serum butyryl cholinesterase activity in rats. J Nutr 1992 122(11) 2283-2291. 

Jackson, K. A., D. A. I. Suter, and D. L. Topping. Oat bran, barley and malted barley lower plasma cholesterol relative to wheat bran but differ in their effects on liver cholesterol in rats fed diet with and without cholesterol. 

Sho, H., I. Chinen, K. Uchihara, and N. Fukuda. Effects of Okinawan sugar cane rind on serum and liver cholesterol and triglyceride levels in the rat. SO081 J Nutr Sci Vitaminol (Tokyo) 1981 ... 

Spielmann, J., Noatsch, A., Brandsch, C., Stangl, G. L, and Eder, K. (2008). Effects of various dietary arginine and lysine concentrations on plasma and liver cholesterol concentrations in rats. Ann. Nutr. Metab. 53(3 ), 223-233. 

LeHoux and Grondin (1993) investigated the effects of chitosan on plasma and liver cholesterol levels, liver weight, and 3-hydroxy-3-methylglutaryl coenzyme A reductase in rats fed on a sterol diet (1% cholesterol and 0.2% cholic acid). Chitosan at a level of 5% lowered plasma and liver cholesterol levels by 54% and 64%, respectively. High MW chitosan (>750 kDa) had less hypocholesterolemic potential than that of 70 kDa. 

Lactitol. Lactitol (4-0-/ -D-galactopyranosyl-D-sorbitol), is a synthetic sugar alcohol produced on reduction of lactose, usually using Raney nickel. It can be crystallized as a mono- or di-hydrate. Lactitol is not metabolized by higher animals it is relatively sweet and hence has potential as a non-nutritive sweetener. It is claimed that lactitol reduces the absorption of sucrose, blood and liver cholesterol levels and to be anticariogenic. It has applications in low-calorie foods (jams, marmalade, chocolate, baked goods) it is non-hygroscopic and can be used to coat moisture-sensitive foods, e.g. sweets. 

Scientists theorize that, due to its chemical similarity, sitostanol competes with cholesterol to be absorbed into the bloodstream from the intestine. This not only interferes with the uptake of cholesterol from the diet, but it also, more importantly, lowers the amount of cholesterol that wends its way into the blood from cholesterol synthesis in the liver. Cholesterol is an essential biochemical, which the liver can supply, but much of it accesses the bloodstream in an indirect fashion. First it s secreted through bile into the intestine, where it plays a role in fat absorption, and then it is absorbed into the blood. Sitostanol blocks this absorption. 

Sources of liver cholesterol (influx) and routes by which cholesterol leaves the liver (efflux). 

The thiolase and HMG-CoA synthase exhibit some regulatory properties in rat liver (cholesterol feeding causes a decrease in these enzyme activities in the cytosol but not in the mitochondria). However, the primary regulation of cholesterol biosynthesis appears to be centered on the HMG-CoA reductase reaction. HMG-CoA reductase is found on the endoplasmic reticulum, has a molecular weight of 97,092, and consists of 887 amino acids in a single polypeptide chain. The sequence of the enzyme was deduced by Michael Brown and Joseph Goldstein from the sequence of a piece of complimentary DNA (cDNA) derived from mRNA that codes for the reductase. The enzyme... 

Based on our knowledge of the facts that (a) lipoproteins are carriers of cholesterol in the blood stream, (b) they are involved in atherogenesis,(c) pectin when supplemented in diet causes lowering of serum and/or liver cholesterol in man as well as a number of laboratory animals and (d) polyanionic glycosaminoglycans interact with lipoproteins, it was of interest to us to investigate the interaction of polyanionic pectin with lipoproteins in order to explain the biochemical basis by which pectin may cause lowering of serum/liver cholesterol levels. 

The significance of the observed interaction between pectin and LDL, and further biochemical elucidation of this interaction, has direct relevance to the etiology and/or cure of atherosclerosis. The role of dietary pectin in lowering of serum and liver cholesterol levels is well established. However, the biochemical basis by which dietary pectin, which is composed of... 

Pectin with 62% D.E. largely counteracted the increase in liver cholesterol levels brought about by dietary cholesterol. Low ester pectin (30% D.E.), polygalacturonic acid (PGA), and 50% esterified PGA were all without effect. Conflicting reports on the efficacy of pectin as a hypocholesterolemic agent may be due to variations in these parameters. For example, citrus pectin was found to be more effective than tomato pectin in lowering serum and hepatic cholesterol levels of rats (79). 

Kamei, M., Ohgaki, S., Kanbe, T., Niiya, I., Mizutani, H., Matsui-Yuasa, I., Otani, S., and Morita, S. 1995. Effects of highly hydrogenated soybean oil and cholesterol on plasma, liver cholesterol, and fecal steroids in rats. Lipids 30, 533-539. 

Peterson, D.W. 1951. Effect of soybean sterols in the diet on plasma and liver cholesterol in chicks. Proc. Soc. Exp. Biol. Med. 78, 143-147. 

It has been suggested that milk thistle may be beneficial in the management of hypercholesterolemia and gallstones. A small trial in humans showed a reduction in bile saturation index and biliary cholesterol concentration. The latter may reflect a reduction in liver cholesterol synthesis. To date, however, there is insufficient evidence to warrant the use of milk thistle for either of these disorders. 

Increased levels of apolipoproteins and rate-limiting enzymes of lipogenesis and their mRNAs have been demonstrated in the liver of nephrotic rats (V5), although increased liver cholesterol synthesis has not been confirmed in nephrotic patients (D9). Cholesterol synthesis in the liver probably does not change during antipro-teinuric treatment (D9). The rate of synthesis of LDL apoprotein B is variable and depends on the presence or absence of hypertriglyceridemia (V6). 

Cholesterol can be obtained either from the diet or it can be synthesized de novo, mainly in the liver. Cholesterol is transported round the body in lipoprotein particles (see Topic K6). The rate of synthesis of cholesterol is dependent on the cellular level of cholesterol. High levels of cholesterol and its metabolites control cholesterol biosynthesis by ... 

Bile salts (or bile acids) are polar derivatives of cholesterol and constitute the major pathway for the excretion of cholesterol in mammals. In the liver, cholesterol is converted into the activated intermediate cholyl CoA which then reacts either with the amino group of glycine to form glycocholate (Fig. 3a), or with the amino group of taurine (H2N-CH2-CH2-S03", a derivative of cysteine) to form taurocholate (Fig. 3b). After synthesis in the liver, the bile salts glycocholate and taurocholate are stored and concentrated in the gall bladder, before release into the small intestine. Since they contain both polar and nonpolar... 

Cholesterol is synthesized from acetyl-CoA in the liver. Cholesterol and a number of natural products from plants (including rubber) are isoprenoid compounds. The isoprenoid unit is a 5-carbon structure. 

Curcumin has been proved to be an effective hypolipidaemic agent (Babu and Srinivasan, 1997). One study validated the role of dietary curcumin in maintaining healthy serum cholesterol levels in diabetic rats. Employing a high-cholesterol diet for the diabetic rats, curcumin exhibited a lowering of cholesterol and phospholipid in treated animals as compared with curcumin-free controls. Liver cholesterol, triglycerides and phospholipid elevated under diabetic conditions were lowered by dietary curcumin. Curcumin induces a... 

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