Cholesterol Retention Research Articles

SYNTHESIS AND CHARACTERIZATION OF CARBOXYMETHYL CHITOSAN-ARG AND CARBOXYMETHYL CHITOSAN-LYS DERIVATIVES

One of the properties of chitosan is their capacity to trap cholesterol. Following this reasoning the incorporation of more amino and alkyl groups will increase the charge density the macromolecule increasing the capability to retain bilic acids. A series of products from chitosan were prepared from the precursor carboxymethyl chitosan (CMQ). The aminoacids arginine and lysine were methylated order to direct the amide bond formation and selectively incorporated carboxymethyl chitosan macromolecule (CMQ-ARG and CMQ-LYS). Preliminary results of in retention capacity human hypercholesterolemic serum are reported. The cholesterol retention capacity was 49.62 ± 1.66 % for CMQ-ARG and 43.72 ± 1.65 % for CMQ-LYS using a 80 mg/mL polymer concentration. On the other hand, the chitosan show a 14.23 ± 0.81 % retention capacity. The increase the amino group chitosan derivatives increase the change density to improve the total binding capacity vitro

Non-HDL cholesterol level is reliable to be an early predictor for vascular inflammation in type 2 diabetes mellitus.

Although LDL is the primary target for lipid-lowering therapy and non-HDL cholesterol is a secondary target in patients with elevated triglyceride (TG) levels, non-HDL cholesterol is still an early, reliable, and practical predictor for vascular inflammation. However, in comparison with LDL, further evidence for superiority in non-HDL cholesterol as the primary therapeutic target is required. A total of 189 type 2 diabetic patients (88 men and 101 women; mean age 58.4 +/- 14.0 years; duration of diabetes 9.8 +/- 4.2 years) who had not used anti-inflammatory agents in the past two years were enrolled in this study. Levels of various lipid fractions and C-reactive protein (CRP) and the cholesterol retention fraction (CRF) were measured. Lipid levels and CRF in samples with CRP levels below or above different cutoffs were compared. Statistically significant differences were seen at all CRP cutoffs in the levels of TG, HDL, and non-HDL cholesterol and the CRF, but no differences were seen in total cholesterol and LDL cholesterol levels. CRP levels correlated with non-HDL cholesterol levels (r = 0.16, P = 0.0236) and the CRF (r = 0.18, P = 0.14), but not with levels of HDL or TG. Besides, non-HDL levels showed a marked correlation with CRF (r = 0.68, P < 0.0001). On the basis of CRP levels, non-HDL levels are reliable in predicting vascular inflammation, and CRF could be another important predictor for cardiovascular events. Our results suggest that the emphasis placed on non-HDL cholesterol should be reevaluated in comparison with that placed on LDL cholesterol.

Retention of aggregated LDL by cultured human coronary artery endothelial cells

Aggregated LDL (AgLDL) accumulates within the subendothelial space of developing atherosclerotic lesions. We were interested to learn whether endothelial cells can interact with AgLDL. Incubation of endothelial cells with AgLDL resulted in apparent cholesterol retention. Microscopic examination revealed that cholesterol retention resulted mainly from endothelial cell surface attachment of AgLDL. Little AgLDL entered endothelial cells consistent with the small amount of endothelial cell degradation of AgLDL. Although endothelial cell retention of AgLDL was inhibited by LDL, AgLDL retention was not blocked by lactoferrin, C7 anti-LDL receptor monoclonal antibody, or receptor-associated protein, suggesting that LDL receptor family members did not mediate this retention. Surface retention of AgLDL depended on microtubule function and could be regulated by the protein kinase C activator, PMA. Treatment of endothelial cells with PMA either before or during, but not after incubation with AgLDL, inhibited retention of AgLDL. Our findings show that endothelial cells can retain AgLDL but internalize and metabolize little of this AgLDL. Thus, it is unlikely that endothelial cells can transport AgLDL out of atherosclerotic lesions, but it is likely that retention of AgLDL affects endothelial function.

Enhanced capacities and selectivities for cholesterol in aqueous media by molecular imprinting: role of novel cross-linkers

Molecularly imprinted polymers are being increasingly investigated as selective sorbents. For the recovery of cholesterol from aqueous media, the utility of the molecularly imprinted polymers has been limited by modest capacities and selectivities, especially when compared with alternative adsorbents reported for the binding of bile acids [Macromolecules 34 (2001) 1548]. This paper describes the use of cholesterol conjugated monomers and cross-linkers, which bind to the template cholesterol molecule by hydrophobic interactions. This leads to enhanced capacities and selectivities during the recovery of cholesterol from aqueous media. The templating effect is clearly seen in the enhanced capacity and selectivity in the retention of cholesterol vis-a-vis stigmasterol and testosterone.

Influence of thiol balance on micellar cholesterol handling by polarized Caco-2 intestinal cells

The in vitro thiol redox modulation of cholesterol homeostasis was investigated in polarized Caco-2 intestinal cells. Cells were pre-incubated with the pro-oxidant compound CuSO 4 or with the antioxidant N-acetylcysteine (NAC), to induce a mild shift of the intracellular redox potential toward, respectively, a more oxidizing or a more reducing equilibrium, via a manipulation of intracellular soluble thiols (glutathione). Then, monolayers were exposed to micellar cholesterol and both the cholesterol uptake and export, as well as the cholesteryl ester cycle, were analyzed. We found that pro-oxidizing conditions induced a significant cholesterol retention within the cells, particularly in the unesterified form (FC), as a result of an augmented sterol incorporation coupled with a reduced rate of FC esterification. A reduction in FC export was also evident. Furthermore, the combination of FC retention and the oxidative imbalance leads to significant alterations of the monolayer integrity, evidenced by both the enhanced tight junction permeability and the lactate dehydrogenase release into the basolateral medium. In contrast, a more reducing environment generated by NAC pre-treatment favors the limitation of the resident time of FC into the cells, via a reduced cholesterol uptake and a concomitant increased cholesterol esterification. In addition, a significant higher FC extrusion into the basolateral medium was also appreciable. Our results indicate that the thiol balance of intestinal cells may be critical for the regulation of cholesterol homeostasis at the intestinal level, influencing the lipid transport throughout the intestinal barrier.

Intimal retention of cholesterol derived from apolipoprotein B100- and apolipoprotein B48-containing lipoproteins in carotid arteries of Watanabe heritable hyperlipidemic rabbits.

The arterial retention of apolipoprotein (apo) B100- and apoB48-containing lipoproteins was simultaneously determined in a rabbit model of human hypercholesterolemia using 3D confocal microscopy. Lipoproteins containing apoB100 (LDL) and apoB48 (chylomicron remnants) were differentially conjugated with fluorophores and simultaneously perfused at equivalent concentrations under physiological conditions in situ through carotid vessels of Watanabe heritable hyperlipidemic rabbits and compared with controls. Retention of lipoproteins was defined as the amount remaining after an extensive washout phase. LDL and chylomicron remnants were both retained, primarily within the subendothelial space. Without a concomitant increase in exposure to lipoproteins, we found a marked increase in the retention of cholesterol within the intima of Watanabe heritable hyperlipidemic rabbits compared with controls, specifically because of increased entrapment of apoB48-containing lipoproteins. Collectively, our data suggest that hypercholesterolemia induced as a consequence of LDL receptor deficiency differentially influences retention of LDL and of chylomicron remnants.

True retention of nutrients on cooking of Australian retail lamb cuts of differing carcass classification characteristics

The true retention of nutrients (proximate principles and cholesterol) on cooking of three retail cuts from lambs classified by weight, sex and fatness score was investigated. Fat retentions of the total cut and of the lean portion of lamb legs and mid-loin chops were not affected by carcass fatness, weight and sex or their interactions, however, the fat retention of the total cut and of the lean portion of forequarter chops was affected by fat score, with forequarter chops from fat score 1 retaining more fat than did chops of carcasses of higher fat score. Overall, fat was lost by all cuts (total cut) on cooking, with only 70–80% of fat being retained, but fat content of lean only increased on cooking (retention >100%), indicating the passage of fat into the lean portion from the external fat cover during the cooking process. Carcass factors and their interactions had little or no effect on the protein, water and ash retentions of the total cut or the lean portions of the three cuts. Cholesterol retention by the lean portion of three cooked lamb cuts was not affected by any carcass factors or their interactions. Cholesterol retentions were ∼99% for total cuts and tended to be ∼102% for the lean portions.

Treating dyslipidemia with statins: The risk-benefit profile

Background Coronary heart disease (CHD), the result of coronary atherosclerosis, is the largest single killer of Americans. Central to the pathogenesis of atherosclerosis are the deposition and retention of cholesterol in the arterial walls. Lipid modification, therefore, is key to CHD prevention. Methods Data from trials evaluating the safety and efficacy of several pharmacologic agents for dyslipidemia were thoroughly reviewed. Results Agents such as bile acid sequestrants, fibric acids, and nicotinic acid have a role in treating dyslipidemia. However, statins are the safest and most effective of the lipid-modifying drugs, reducing the incidence of CHD by as much as 21% to 43%. Despite the overall safety and efficacy of these agents, many patients undergoing statin therapy fail to achieve the treatment goals specified in the National Cholesterol Education Program Adult Treatment Panel III guidelines, often because of suboptimal use, tolerability problems, or lack of compliance. Although adverse effects of statins are generally mild and transient, more serious adverse effects, including myotoxicity, liver toxicity, and rhabdomyolysis, are still possible with statin monotherapy and are more common in patients receiving concomitant therapy with other drugs metabolized by the cytochrome P-450 enzyme system. Conclusions Because of the overall safety and efficacy of the statins, more patients with or at risk for CHD should be receiving aggressive therapy to lower low-density lipoprotein cholesterol levels and reduce CHD risk. (Am Heart J 2003;145:387-96.)

Intimal retention of lipoprotein cholesterol in carotid arteries from Watanabe rabbits

Intimal retention of lipoprotein cholesterol in carotid arteries from Watanabe rabbits

Inhibition of Intracellular Cholesterol Transport Alters Presenilin Localization and Amyloid Precursor Protein Processing in Neuronal Cells

Generation of amyloid-beta (Abeta) from the amyloid precursor protein (APP) requires proteolytic cleavage by two proteases, beta- and gamma-secretase. Several lines of evidence suggest a role for cholesterol on secretase activities, although the responsible cellular mechanisms remain unclear. Here we show that alterations in cholesterol transport from late endocytic organelles to the endoplasmic reticulum have important consequences for both APP processing and the localization of gamma-secretase-associated presenilins (PS). Exposure of neuronal cells to cholesterol transport-inhibiting agents resulted in a marked decrease in beta-cleavage of full-length APP. In contrast, gamma-secretase activity on APP C-terminal fragments was enhanced, increasing the production of both Abeta40 and Abeta42. Remarkably, retention of cholesterol in endosomal/lysosomal compartments induced PS1 and PS2 to accumulate in Rab7-positive vesicular organelles implicated in cholesterol sorting. Accumulation of PS in vesicular compartments was prominent in both Chinese hamster ovary cells deficient in Niemann-Pick C1 protein as well as in neuronal cells exposed to the cholesterol transport-inhibiting agent U18666A. Because Abeta42 also localized to PS1-containing vesicular compartments, organelles involved in cholesterol transport might represent an important site for gamma-secretase activity. Our results suggest that the subcellular distribution of cholesterol may be an important factor in how cholesterol alters Abeta production and the risk of Alzheimer's disease.

Genetic basis of sitosterolemia.

The molecular mechanisms regulating the amount of dietary cholesterol retained by the body, as well as the body's ability to exclude other dietary sterols selectively, are poorly understood. An average Western diet will contain approximately 250-500 mg of dietary cholesterol and approximately 200-400 mg of non-cholesterol sterols, of which plant sterols are the major constituents. Approximately 50-60% of dietary cholesterol is absorbed and retained by the normal human body, but less than 1% of the non-cholesterol sterols are retained. There thus exists a subtle mechanism that allows the body to distinguish between cholesterol and non-cholesterol sterols. In sitosterolemia, a rare autosomal recessive disorder, affected individuals hyperabsorb and retain not only cholesterol but also all other sterols, including plant and shellfish sterols from the intestine. Consequently, patients with this disease have very high levels of plant sterols in the plasma, and develop tendon and tuberous xanthomas, accelerated atherosclerosis, and premature coronary artery disease. The STSL locus has been mapped to human chromosome 2p21. Mutations in two tandem ABC genes, ABCG5 and ABCG8, encoding sterolin-1 and -2, respectively, are now known to be mutant in sitosterolemia. The identification of these genes should now lead to a better understanding of the molecular mechanism(s) governing the highly selective absorption and retention of cholesterol by the body. Indeed, it is the very existence of this disease that has given credence to the hypothesis that there is a molecular pathway that regulates dietary cholesterol absorption and sterol excretion by the body.

Reduction of Sphingomyelin Level without Accumulation of Ceramide in Chinese Hamster Ovary Cells Affects Detergent-resistant Membrane Domains and Enhances Cellular Cholesterol Efflux to Methyl-β-cyclodextrin

We examined the effects of reduction of sphingomyelin level on cholesterol behavior in cells using 2 types of Chinese hamster ovary cell mutants deficient in sphingomyelin synthesis: LY-A strain defective in intracellular trafficking of ceramide for sphingomyelin synthesis, and LY-B strain defective in the enzyme catalyzing the initial step of sphingolipid biosynthesis. Although the sphingomyelin content in LY-A and LY-B cells was approximately 40 and approximately 15%, respectively, of the wild-type level without accumulation of ceramide, these mutant cells were almost identical in cholesterol content and also in plasma membrane cholesterol level to the wild-type cells. However, density gradient fractionation analysis of Triton X-100-treated lysates of cells prelabeled with [(3)H]cholesterol showed that the [(3)H]cholesterol level in the low-density floating fraction was lower in sphingomyelin-deficient cells than in wild-type cells. When cells were exposed to methyl-beta-cyclodextrin, cholesterol was more efficiently fluxed from sphingomyelin-deficient cells than wild-type cells. These results suggest that the steady state level of cholesterol at the plasma membrane is little affected by the sphingomyelin levels in Chinese hamster ovary cells, but that sphingomyelin levels play an important role in the retention of cholesterol in the plasma membrane against efflux to extracellular cholesterol-acceptors, due to interaction between sphingomyelin and cholesterol in detergent-resistant membrane domains.

Retention and separation studies of cholesterol and bile acids using thermostated thin-layer chromatography

The influence of temperature on retention and separation of cholesterol and bile acids, using reversed-phase thin-layer chromatography, was studied. As mobile phases methanol–water mixtures of various compositions were used. Chromatographic experiments were performed using vapor-saturated chambers at temperatures ranging from 5 to 60°C. A linear relationship between R M values and temperature (1/ T) as well as mobile phase composition was observed. The elution order of steroids under the conditions investigated was discussed. Each chromatogram was evaluated using simple optimization parameters and the best chromatographic conditions for the separation of multicomponent samples were chosen.

Accumulation of co-localised unesterified cholesterol and neutral lipids within vacuolised elastin fibres in athero-prone areas of the human aorta

To investigate whether there are alterations of elastin fibres in the arterial intima at the pre-atherosclerotic stage, grossly normal areas of human thoracic aorta were taken soon after death from 13 healthy trauma victims whose ages ranged from 16 to 40 years. Two areas were compared: atherosclerosis-prone (AP) areas localised to the dorsal aspect of the aorta along the rows of intercostal branch origins, and atherosclerosis-resistant (AR) areas from the ventral aorta. Electron microscopic analysis combined with cytochemical staining was applied. Unesterified cholesterol was identified using the filipin-staining technique while neutral lipids were visualised by the OTO-technique. Intimal features were studied by combining the filipin-staining and the OTO-technique. Electron microscopical examination showed that in both AR and AP areas, some elastin fibres in the intima were vacuolised. Unesterified cholesterol was found to be predominantly localised in the musculoelastic layer, in particular, inside the vacuolised elastin fibres. This localisation was seen in all 13 AP areas studied in contrast to the AR areas where it was observed in only four of 13 aortas studied ( P<0.0005, χ 2-test). Accumulation of neutral lipids inside vacuolised elastin fibres was found in five out of 13 AP areas but was not observed in any of the AR areas ( P=0.01, χ 2). A combination of the filipin-staining and OTO-techniques showed that some deposits of neutral lipids and unesterified cholesterol within vacuolised elastin fibres were independently located from each other, but more frequently, neutral lipids were co-located with unesterified cholesterol. The present observations indicate a difference between AP and AR intimal areas which, in particular, relates to the structure of elastin fibres in the musculoelastic layer. The observations suggest that alterations of the extracellular matrix are involved in the trapping and retention of cholesterol and neutral lipids within the intima at an early stage in the development of atherosclerotic lesions.

Hypertriglyceridemia and Atherosclerosis

Letters1 January 1998Hypertriglyceridemia and AtherosclerosisW.E. Feeman, Jr., MDW.E. Feeman, Jr., MDBowling Green, OH 43402Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-128-1-199801010-00022 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:I may be able to shed some light on the quandary concerning the role of triglycerides in the pathogenesis of atherothrombotic disease, as voiced by Dr. Ginsberg in his recent editorial [1]. I am the chief investigator for the Bowling Green Study of the primary and secondary prevention of atherothrombotic disease [2, 3]. To date, I have compiled an age and sex registry of 668 patients who developed some form of the disease between 4 November 1974 and 1 January 1997.The Bowling Green Study uses as its lipid predictor the cholesterol retention fraction ([low-density lipoprotein (LDL) ...

Established and Emerging Strategies for Inhibition of Cholesterol Absorption

The growing evidence linking elevated plasma cholesterol levels to increased risk of heart disease and the demonstration of a positive correlation between plasma levels of low density lipoprotein cholesterol and cholesterol absorption efficiency in humans have been a major impetus for efforts to develop cholesterol absorption inhibitors. Not only do such agents act on a major component of the total cholesterol turnover within the .body, but, since they are directed at a cholesterol pool that is external to the circulation (i.e. intestinal lumen), there is potential for the development of efficacious compounds that function non-systemically and thereby avoid the toxicity issues associated with agents that must enter the circulation to act. The potential for such agents is already evident from the clinical experience with neomycin and B-sitosterol which have yielded moderate success in the treatment of hypercholesterolemic patients. The creation of more efficacious compounds is focused on the development of inhibitors of specific enzymes considered to facilitate the cholesterol absorption process and on non-specific agents that enhance cholesterol retention within the intestinal contents by perturbing cholesterol distribution and exchange among the various lipid phases of the contents. In addition, a new method for blocking cholesterol uptake is proprosed that is based on the inhibition of pancreatic phospholipase A2.

Composition and nutritive value of acidulated fatty acids, degummed canola oils and tallow as energy sources for starting broiler chicks

Two experiments were conducted to determine the nutritive value of various lipid sources when fed to starting broiler chicks. In Experiment 1, two replicates of 96 and 144 1-day-old, male broiler chicks were fed diets supplemented with 80 g kg −1 of either tallow, acidulated fatty acid (AFA), water degummed canola oil or super degummed canola oil. Each diet was fed ad libitum to ten pens of six birds. In Experiment 2, 72 1-day-old broiler chicks were fed diets supplemented with 80 g kg −1 of either tallow or AFA or a combination of 80 g kg −1 AFA and 10 g kg −1 glycerol. Each diet was fed ad libitum to four pens of birds with three males and three females per pen. All diets (meal form) were based on wheat and soya-bean meal and contained chromic oxide (5 g kg −1) as a digestibility marker (Table 1). Chicks were weighed individually at the start of the experiment and at weekly intervals thereafter for the duration of the 3 week feeding trials. Feed consumption was determined on a pen basis at the time of the weekly weighing. During the third week of each experiment, samples of droppings were collected in order to measure nutrient retention. In Experiment 1, birds fed the diets supplemented with either the water degummed or the super degummed canola oil gained faster ( P < 0.05) than brids fed diets supplemented with tallow or AFA. In addition, higher feed intakes ( P < 0.05) and improved feed gain ratio ( P < 0.05) were noted for the water degummed canola oil. Birds fed the diet supplemented with water degummed canola oil had higher dry matter and energy retention ( P < 0.05) compared with birds fed AFA. In Experiment 2, no significant differences were found in growth, feed intake, feed gain ratio, liver and heart weight, serum cholesterol or nutrient retention as a result of treatment. Fat source had a significant ( P < 0.05) influence on the fatty acid profile of abdominal fat with birds fed tallow showing higher levels of saturated fatty acids and lower levels of unsaturated fatty acids in comparison with birds fed AFA. The overall results of these experiments indicate that degummed canola oils and to a lesser extent AFA, are acceptable supplementary sources of energy for use in broiler diets. Supplementation with glycerol failed to improve the performance of birds fed diets containing AFA.

Cholesterol and 25‐hydroxycholesterol retention in specimens of liver and aorta prepared for electron microscopy. II. Effect of filipin, osmium, digitonin and saponin

Sprague-Dawley rats were injected intraperitoneally with [1 alpha, 2 alpha(n)-3H]cholesterol or 25-hydroxy-[26,27-3H]cholesterol, and one and five days later liver and aortic tissues were fixed. The extent to which these sterols were lost from the tissues during preparation for electron microscopy (EM) was examined utilizing different fixation procedures and various protective agents. Radioactive tracers, scintillation counting and standard EM techniques were used. Although most of the procedures examined caused major lipid losses, useful fixation procedures that allow retention of cholesterol or 25-hydroxy-cholesterol in liver and aortic tissues were found and are described here.

Cholesterol and 25-hydroxycholesterol retention in specimens of liver and aorta prepared for electron microscopy. I. Standard fixation methods and metabolism of the labeled sterols.

In the present work, several preparatory procedures commonly used for electron microscopy (EM) were evaluated as to their ability to preserve cholesterol (CHO) and CHO derivatives in tissue. We also determined in several rat tissues to what extent the sterols used as tracers are metabolized. Sprague-Dawley rats were injected intraperitoneally with [1 alpha,2 alpha(n)-3H]cholesterol ([3H]CHO) and 25-hydroxy-[26,27-3H]cholesterol ([3H]25-OH-CHO). Lipids of the liver, aorta and brain were extracted one and five days after injection, and the distribution of the labeled lipids was followed by thin-layer chromatography. When labeled CHO was injected as tracer, most of the radioactivity remained associated with the CHO fraction. When 25-hydroxycholesterol (25-OH-CHO) was used, we found that it was mostly metabolized to yield more polar compounds. Our results show that the loss of CHO and CHO derivatives from tissues depends not only on the preparatory procedure used for EM, but also on the type of tissue studied.

Therapeutic Efficacy of Liv. 52 in Experimentally Induced Hepatopathy in Sheep

Abstract Bhaumik, A. and Sharma, M.C. 1993. Therapeutic efficacy of Liv. 52 in experimentally induced hepatopathy in sheep. J. Appl. Anim. Res. 3: 137–142. Hepatopathy was induced in 12 healthy adult sheep with paracetamol. They were dividedin 2 equal groups of 6 animals each. One group served as untreated control whereas 5 gof Liv. 52powder was given twice a day for 10 days as therapy in the other group. Different haematobiochemical and dye excretion tests were performed to evaluate the therapeutic efficacy. Decrease in Hb, TEC, blood glucose level, and A:G ratio was observed following induction of hepatopathy, whereas TLC, cholesterol, bilirubin, AST, ALT and BSP percent retention showed increase in their values. Most of these values reversed back to normalcy rapidly and effectively in the treated animals while they remained much altered in the untreated animals till the end of the experiment.