Early alterations in serum creatine kinase and total cholesterol following high intensity eccentric muscle actions

Aim. The purpose of this experiment was to assess the levels of muscle soreness, serum total cholesterol (TC) and creatine kinase (CK) in the first 48 hours following fatiguing eccentric exercise performed with the triceps brachii. Methods. Eleven untrained male college students performed a total of 50 eccentric elbow extensions in 8 sets (6x7 and 2x4) with a load equal to 85% of their maximal concentric elbow extension strength. Isometric elbow extension strength, muscle soreness and circumference, and serum CK and TC concentrations were measured before, immediately after, and 2, 24 and 48 hours after the exercise. Results. Statistically reliable changes in isometric strength, serum CK and TC, muscle soreness and upper arm circumference occurred within the first 48 hours following eccentric exercise. Serum TC concentrations exhibited a very rapid (within 2 hours) reduction from pre-exercise values after eccentric exercise to a relatively stable concentration of approximately 85% of baseline. Conclusion. These results suggest that serum TC concentration may follow the time-course of reductions in force generating capacity more closely than other biochemical markers of muscle damage.

Pseudo-ternary phase diagrams of aqueous mixtures of Quil A, cholesterol and phospholipid prepared by the lipid-film hydration method

Pseudo-ternary phase diagrams of the polar lipids Quil A, cholesterol (Chol) and phosphatidylcholine (PC) in aqueous mixtures prepared by the lipid film hydration method (where dried lipid film of phospholipids and cholesterol are hydrated by an aqueous solution of Quil A) were investigated in terms of the types of particulate structures formed therein. Negative staining transmission electron microscopy and polarized light microscopy were used to characterize the colloidal and coarse dispersed particles present in the systems. Pseudo-ternary phase diagrams were established for lipid mixtures hydrated in water and in Tris buffer (pH 7.4). The effect of equilibration time was also studied with respect to systems hydrated in water where the samples were stored for 2 months at 4degreesC. Depending on the mass ratio of Quil A, Chol and PC in the systems, various colloidal particles including ISCOM matrices, liposomes, ring-like micelles and worm-like micelles were observed. Other colloidal particles were also observed as minor structures in the presence of these predominant colloids including helices, layered structures and lamellae (hexagonal pattern of ring-like micelles). In terms of the conditions which appeared to promote the formation of ISCOM matrices, the area of the phase diagrams associated with systems containing these structures increased in the order: hydrated in water/short equilibration period < hydrated in buffer/short equilibration period < hydrated in water/prolonged equilibration period. ISCOM matrices appeared to form over time from samples, which initially contained a high concentration of ring-like micelles suggesting that these colloidal structures may be precursors to ISCOM matrix formation. Helices were also frequently found in samples containing ISCOM matrices as a minor colloidal structure. Equilibration time and presence of buffer salts also promoted the formation of liposomes in systems not containing Quil A. These parameters however, did not appear to significantly affect the occurrence and predominance of other structures present in the pseudo-binary systems containing Quil A. Pseudo-ternary phase diagrams of PC, Chol and Quil A are important to identify combinations which will produce different colloidal structures, particularly ISCOM matrices, by the method of lipid film hydration. Colloidal structures comprising these three components are readily prepared by hydration of dried lipid films and may have application in vaccine delivery where the functionality of ISCOMs has clearly been demonstrated. (C) 2003 Elsevier B.V. All rights reserved.

A comparison of pseudo-ternary diagrams of aqueous mixtures of Quil A, cholesterol and phospholipid prepared by lipid-film hydration and dialysis

Pseudo-ternary diagrams for Quil A, phospholipid (phosphatidylcholine (PC) or phosphatidylethanolamine (PE)) and cholesterol were established in order to identify combinations that result in the formation of immune-stimulating complex (ISCOM) matrices and other colloidal structures produced by these three components in aqueous systems following lipid-film hydration or dialysis (methods that can be used to produce ISCOMs). In addition, the effect of equilibration time (1 month at 4degreesC) on the structures formed by the various combinations of the three components was investigated. Depending on the ratio of Quil A, cholesterol and phospholipid, different colloidal particles, including ISCOM matrices, liposomes and ring-like micelles, were found irrespective of the preparation method used. In contrast, worm-like micelles were only observed in systems prepared by lipid-film hydration. For samples prepared by dialysis, ISCOM matrices were predominantly found near the Quil A apex of the pseudo-ternary diagram (> 50% Quil A). On the other hand, for samples prepared by lipid-film hydration, ISCOM matrices were predominantly found near the phospholipid apex of the pseudo-ternary diagram (> 50% phospholipid). The regions in the pseudo-ternary diagrams in which ISCOM matrices were observed increased following an extended equilibration time, particularly for samples prepared by lipid-film hydration. Differences were also observed between pseudoternary diagrams prepared using either PE or PC as phospholipids.

Investigation of the low-density lipoprotein receptor gene and cholesterol as a risk factor for migraine

The Low-Density Lipoprotein Receptor (LDLR) gene is a cell surface receptor that plays an important role in cholesterol homeostasis. We investigated the (TA)n polymorphism in exon 18 of the LDLR gene on chromosome 19p13.2 performing an association analysis in 244 typical migraine-affected patients, 151 suffering from migraine with aura (MA), 96 with migraine without aura (MO) and 244 unaffected controls. The populations consisted of Caucasians only, and controls were age- and sex-matched. The results showed no significant difference between groups for allele frequency distributions of the (TA)n polymorphism even after separation of the migraine-affected individuals into subgroups of MA and MO affected patients. This is in contradiction to Mochi et al. [Mochi M, Cevoli S, Cortelli P, Pierangeli G, Scapoli C, Soriani S, Montagna P. Investigation of an LDLR gene polymorphism (19p13.2) in susceptibility to migrane without aura. J Neurol Sci 2003; 213 (1-2): 7-10.] who found a positive association of this variant with MO. Our study discusses possible differences between the two studies and extends this research by investigating circulating cholesterol levels in a migraine-affected population. (C) 2004 Elsevier B.V. All rights reserved.

Expression of caveolin-1 enhances cholesterol efflux in hepatic cells

HepG2 cells were stably transfected with human caveolin-1 (HepG2/cav cells). Transfection resulted in expression of caveolin-1 mRNA, a high abundance of caveolin-1 protein, and the formation of caveolae on the plasma membrane. Cholesterol efflux from HepG2/cav cells was 280 and 45% higher than that from parent HepG2 cells when human plasma and human apoA-I, respectively, were used as acceptors. The difference in efflux was eliminated by treatment of cells with progesterone. There was no difference in cholesterol efflux to cyclodextrin. Cholesterol efflux from plasma membrane vesicles was similar for the two cell types. Transfection led to a 40% increase in the amount of plasma membrane cholesterol in cholesterol-rich domains ( caveolae and/or rafts) and a 67% increase in the rate of cholesterol trafficking from intracellular compartments to these domains. Cholesterol biosynthesis in HepG2/cav cells was increased by 2-fold, and cholesterol esterification was reduced by 50% compared with parent HepG2 cells. The proliferation rate of transfected cells was significantly lower than that of non-transfected cells. Transfection did not affect expression of ABCA1 or the abundance of ABCA1 protein, but decreased secretion of apoA-I. We conclude that overexpression of caveolin-1 in hepatic cells stimulates cholesterol efflux by enhancing transfer of cholesterol to cholesterol-rich domains in the plasma membrane.

Selective stimulation of caveolar endocytosis by glycosphingolipids and cholesterol

Internalization of some plasma membrane constituents, bacterial toxins, and viruses occurs via caveolae; however, the factors that regulate caveolar internalization are still unclear. Here, we demonstrate that a brief treatment of cultured cells with natural or synthetic glycosphingolipids (GSLs) or elevation of cholesterol (either by acute treatment with mbeta-cyclodextrin/cholesterol or by alteration of growth conditions) dramatically stimulates caveolar endocytosis with little or no effect on other endocytic mechanisms. These treatments also stimulated the movement of GFP-labeled vesicles in cells transfected with caveolin-1-GFP and reduced the number of surface-connected caveolae seen by electron microscopy. In contrast, overexpression of caveolin-1 decreased caveolar uptake, but treatment with GSLs reversed this effect and stimulated caveolar endocytosis. Stimulation of caveolar endocytosis did not occur using ceramide or phosphatidylcholine and was not due to GSL degradation because similar results were obtained using a nonhydrolyzable GSL analog. Stimulated caveolar endocytosis required src kinase and PKC-alpha activity as shown by i) use of pharmacological inhibitors, ii) expression of kinase inactive src or dominant negative PKCalpha, and iii) stimulation of src kinase activity upon addition of GSLs or cholesterol. These results suggest that caveolar endocytosis is regulated by a balance of caveolin-1, cholesterol, and GSLs at the plasma membrane.

Anlaysis of complementary expression profiles following WT1 induction versus repression reveals the cholesterol/fatty acid synthetic pathways as a possible major target of WT1

The Wilms' tumour suppressor gene, WT1, encodes a zinc-finger protein that is mutated in Wilms' tumours and other malignancies. WT1 is one of the earliest genes expressed during kidney development. WT1 proteins can activate and repress putative target genes in vitro, although the in vivo relevance of such target genes often remains unverified. To better understand the role of WT1 in tumorigenesis and kidney development, we need to identify downstream target genes. In this study, we have expression pro. led human embryonic kidney 293 cells stably transfected to allow inducible WT1 expression and mouse mesonephric M15 cells transfected with a WT1 antisense construct to abolish endogenous expression of all WT1 isoforms to identify WT1-responsive genes. The complementary overlap between the two cell lines revealed a pronounced repression of genes involved in cholesterol biosynthesis by WT1. This pathway is transcriptionally regulated by the sterol responsive element-binding proteins (SREBPs). Here, we provide evidence that the C-terminal end of the WT1 protein can directly interact with SREBP, suggesting that WT1 may modify the transcriptional function of SREBPs via a direct protein-protein interaction. Therefore, the tumour suppressor activities of WT1 may be achieved by repressing the mevalonate pathway, thereby controlling cellular proliferation and promoting terminal differentiation.

Effects of pravastatin on coronary events in 2073 patients with low levels of both low-density lipoprotein cholesterol and high-density lipoprotein cholesterol: results from the LIPID study

Aims Fibrates or nicotinic acid are usually recommended for secondary prevention of coronary heart disease in patients with low plasma levels of both low-density tipoprotein cholesterol (LDL-C) less than or equal to140 mg/dL (less than or equal to3.6 mmol/L) and high-density lipoprotein cholesterol (HDL-C) less than or equal to40 mg/dL (less than or equal to1.03 mmol/L). The LIPID trial, a randomised, placebo-controlled trial in 9014 patients at 87 centres in Australia and New Zealand, provided an opportunity to investigate the effects of an HMG-CoA reductase inhibitor in patients with tow LDL-C and tow HDL-C. Methods and results Participants in this post hoc substudy were 2073 patients aged 31-75 years with baseline LDL-C less than or equal to140 mg/dL (less than or equal to3.6 mmoL/L), HDL-C less than or equal to40 mg/dL (less than or equal to1.03 mmol/L), and triglyceride less than or equal to300 mg/dL (less than or equal to3.4 mmol/L). The relative risk reduction with pravastatin treatment was 27% for major coronary events (95% Cl 8-42%), 27% for coronary heart disease mortality (95% CI 0-47%), 21% for all-cause mortality (95% Cl 0-38%), and 51% for stroke (95% CI 24-69%). The number needed to treat to prevent a major coronary event over 6 years was 22. Conclusions Treatment with pravastatin in patients with both low LDL-C and low HDL-C significantly reduced major coronary events, stroke, and all-cause mortality. The level of HDL-C is crucial to the risk of recurrent CHD events and, consequently, the benefit of lowering LDL-C. (C) 2004 Published by Elsevier Ltd on behalf of The European Society of Cardiology.

Farnesoid X receptor agonism - a new approach to the treatment of cholesterol gallstone disease

Gallstone disease is very common among native Americans and Hispanics, and similar to 20 million patients are treated for this disease annually in the US. The nuclear farnesoid X receptor (FXR) is the receptor for bile acids, and GW4064 is a synthetic agonist at the FXR. FXR-/- mice fed a lithogenic diet (high fat, cholesterol and cholic acid) are more susceptible to gallstone disease than wild-type mice with the same mixed background, thus establishing that the ablation of FXR is associated with this disease. The C57L mouse is susceptible to gallstone formation. When C57L mice are fed a lithogenic diet for a week, the bile contains large aggregates of cholesterol precipitates, and two of five C57L mice had macroscopic cholesterol crystals. in contrast, when C57L mice were fed the lithogenic diet and administered GW4064 100 mg/kg/day by oral gavage, there was no precipitation of cholesterol. Treatment with this agent also increased bile salt and phospholipid concentration, and prevented gallbladder epithelium damage. As FXR agonism with GW4064 has been shown to be useful in a mouse model of cholesterol gallstone disease, it should undergo further development for the treatment of this condition.

Berberine - a novel approach to cholesterol lowering

Although low-density lipoprotein (LDL)-cholesterol lowering with the statins reduces the mortality and morbidity associated with coronary artery disease, considerable mortality and morbidity remains. Berberine upregulates the LDL receptor (LDLR) by a mechanism distinct from that of the statins, which involves stabilising the LDLR mRNA. In hamsters fed a high-fat and high-cholesterol diet for 2 weeks, the oral administration of berberine 100 mg/kg for 10 days reduced total serum cholesterol from &SIM; 4.8 to 2.7 mmol/l, and LDL-cholesterol from &SIM; 2.5 to 1.4 mmol/l. In subjects with hypercholesterolaemia, berberine hydrochloride (0.5 g b.i.d. for 3 months) reduced LDL-cholesterol (from 3.2 to 2.4 mmol/l) without any effect on high-density lipoprotein-cholesterol. Berberine also caused a reduction in triglyceride levels from 2.3 to 1.5 mmol/l. As berberine and statins both upregulate LDLR, their lipid-lowering profiles are similar. Thus, this mechanism is unlikely to make berberine an attractive alternative to statins for lipid lowering in most circumstances. However, the other effects of berberine (anti hypertensive, inotropic and class III antiarrhythmic properties) may make it a useful agent in the treatment of cardiovascular disease.

Caveolin, cholesterol, and lipid bodies

In mammalian cells a complex interplay regulates the distribution of cholesterol between intracellular membrane compartments. One important aspect of cholesterol regulation is intracellular cholesterol storage in neutral lipid storage organelles called lipid droplets or lipid bodies (LBs). Recent work has thrust the LB into the limelight as a complex and dynamic cellular organelle. LBs play a crucial role in maintaining the cellular levels of cholesterol by regulating the interplay between lipid storage, hydrolysis and traffickin,-. Studies of caveolins, caveolar membrane proteins linked to lipid regulation, are providing new insights into the role of LBs in regulating cholesterol balance. (c) 2005 Elsevier Ltd. All rights reserved.

Cholesterol and fatty acids regulate dynamic caveolin trafficking through the golgi complex and between the cell surface and lipid bodies

Caveolins are a crucial component of plasma membrane (PM) caveolae but have also been localized to intracellular compartments, including the Golgi complex and lipid bodies. Mutant caveolins associated with human disease show aberrant trafficking to the PM and Golgi accumulation. We now show that the Golgi pool of mainly newly synthesized protein is detergent-soluble and predominantly in a monomeric state, in contrast to the surface pool. Caveolin at the PM is not recognized by specific caveolin antibodies unless PM cholesterol is depleted. Exit from the Golgi complex of wild-type caveolin-1 or -3, but not vesicular stomatitis virus-G protein, is modulated by changing cellular cholesterol levels. In contrast, a muscular dystrophy-associated mutant of caveolin-3, Cav3P104L, showed increased accumulation in the Golgi complex upon cholesterol treatment. In addition, we demonstrate that in response to fatty acid treatment caveolin can follow a previously undescribed pathway from the PM to lipid bodies and can move from lipid bodies to the PM in response to removal of fatty acids. The results suggest that cholesterol is a rate-limiting component for caveolin trafficking. Changes in caveolin flux through the exocytic pathway can therefore be an indicator of cellular cholesterol and fatty acid levels.

Transcriptional profile reveals altered hepatic lipid and cholesterol metabolism in hyposulfatemic NaS1 null mice

Sulfate plays an essential role in human growth and development, and its circulating levels are maintained by the renal Na+-SO42- cotransporter, NaS1. We previously generated a NaS1 knockout ( Nas1(-/-)) mouse, an animal model for hyposulfatemia, that exhibits reduced growth and liver abnormalities including hepatomegaly. In this study, we investigated the hepatic gene expression profile of Nas1(-/-) mice using oligonucleotide microarrays. The mRNA expression levels of 92 genes with known functional roles in metabolism, cell signaling, cell defense, immune response, cell structure, transcription, or protein synthesis were increased ( n = 51) or decreased ( n = 41) in Nas1(-/-) mice when compared with Nas1(-/-) mice. The most upregulated transcript levels in Nas1(-/-) mice were found for the sulfotransferase genes, Sult3a1 ( approximate to 500% increase) and Sult2a2 ( 100% increase), whereas the metallothionein-1 gene, Mt1, was among the most downregulated genes ( 70% decrease). Several genes involved in lipid and cholesterol metabolism, including Scd1, Acly, Gpam, Elov16, Acsl5, Mvd, Insig1, and Apoa4, were found to be upregulated ( >= 30% increase) in Nas1(+/+) mice. In addition, Nas1(+/+) mice exhibited increased levels of hepatic lipid ( approximate to 16% increase), serum cholesterol ( approximate to 20% increase), and low-density lipoprotein ( approximate to 100% increase) and reduced hepatic glycogen ( approximate to 50% decrease) levels. In conclusion, these data suggest an altered lipid and cholesterol metabolism in the hyposulfatemic Nas1(-/-) mouse and provide new insights into the metabolic state of the liver in Nas1(-/-) mice.

Cholesterol-induced caveolin targeting to lipid droplets in adipocytes: A role for caveolar endocytosis

We have investigated the targeting of caveolin to lipid bodies in adipocytes that express high levels of caveolins and contain well-developed lipid droplets. We observed that the lipid droplets isolated from adipocytes of caveolin-1 knock out mice contained dramatically reduced levels of cholesterol, indicating that caveolin is required for maintaining the cholesterol content of this organelle. Analysis of caveolin distribution by cell fractionation and fluorescent light microscopy in 3T3-L1 adipocytes indicated that addition of cholesterol rapidly stimulated translocation of caveolin to lipid droplets. The cholesterol-induced trafficking of caveolins to lipid droplets was shown to be dynamin- and protein kinase C (PKC)-dependent and modulated by src tyrosine kinase activation, suggesting a role for caveolar endocytosis in this novel trafficking pathway. Consistent with this, caveolae budding was stimulated by cholesterol addition. The present data identify lipid droplets as potential target organelles for caveolar endocytosis and demonstrate a role for caveolin-1 in the maintenance of free cholesterol levels in adipocyte lipid droplets.