| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Accuracy of cholesterol measurements in Italian clinical laboratories. Joint project GISSI prevention--Italian Society of Clinical Biochemistry. SIBioC GISSI Prevenzione Group Graziani, M. S., F. Ceriotti, et al. (1997), Eur J Clin Chem Clin Biochem 35(4): 311-5. Abstract: We report the results of an external quality assessment scheme for serum total cholesterol measurement involving about 100 Italian laboratories participating in an epidemiological study of post myocardial infarction. Two frozen human serum pools with Abell-Kendall assigned values are distributed quarterly at the laboratories (up to now seven events occurred); the obtained results are evaluated and discussed. In one exercise (# 5) duplicated measurements were repeated on three different days. Eighty-five to 98% of the laboratories obtained results within the total error limits (+/- 8.9%). But, while precision (calculated on the six replicates of exercise # 5) is good (90% of the laboratories obtained CV < 3%), inaccuracy problems are evident in every event. Indeed the mean bias from the reference method value ranged from 1.54 and 3.49% in the various events. |
| Accuracy of Reflotron cholesterol assays evaluated Boerma, G. J. (1990), Clin Chem 36(3): 578-9. |
| Accuracy of the triglyceride to high-density lipoprotein cholesterol ratio for prediction of the low-density lipoprotein phenotype B Hanak, V., J. Munoz, et al. (2004), Am J Cardiol 94(2): 219-22. Abstract: This study examined the accuracy of a triglyceride/high-density lipoprotein (HDL) cholesterol ratio of 3.8 for the prediction of low-density lipoprotein (LDL) phenotype B. The ratio of 3.8 was based on Adult Treatment Panel recommendations for normal fasting triglycerides (<150 mg/dl) and HDL cholesterol (>40 mg/dl). Fasting blood samples were obtained from 658 patients. LDL phenotype analysis was performed by nuclear magnetic resonance spectroscopy. A triglyceride/HDL cholesterol ratio of 3.8 divided the distribution of LDL phenotypes with 79% (95% confidence interval CI 74 to 83) of phenotype B greater than and 81% (95% CI 77 to 85) of phenotype A less than the ratio of 3.8. The ratio was reliable for identifying LDL phenotype B in men and women. |
| Accurate direct determination of low-density lipoprotein cholesterol using an immunoseparation reagent and enzymatic cholesterol assay Pisani, T., C. P. Gebski, et al. (1995), Arch Pathol Lab Med 119(12): 1127-35. Abstract: Clinical laboratories currently estimate low-density lipoprotein cholesterol using the Friedewald formula, which requires fasting specimens and is subject to error with increasing triglyceride levels. We describe a rapid method for isolating low-density lipoproteins using the Direct LDL Immunoseparation Reagent for subsequent measurement of cholesterol by conventional assay. This method meets current guidelines for precision with within-run and run-to-run coefficients of variation of less than 3%. Results are in good agreement with the beta quantification reference method (Direct LDL-C = 1.03 beta quantification -0.06 mmol/L, 2.4 mg/dL r = 0.980), there is minimal bias associated with increasing triglycerides or high-density lipoprotein cholesterol, and patient fasting is not required for accurate analysis. The Direct LDL Immunoseparation Reagent overcomes drawbacks of the Friedewald formula and appears to be suitable for accurate quantitation of low-density lipoprotein cholesterol in the routine laboratory. |
| Accurate measurement of serum total cholesterol: the need for standardization Naito, H. K. and Y. S. Kwak (1992), J Am Coll Nutr 11 Suppl: 8S-15S. Abstract: Heightened awareness of the importance of cholesterol and heart disease has increased cholesterol testing in the United States. The demand for reliable cholesterol measurements has become a focal concern of the patient as well as the clinician. This paper covers the major analytical and preanalytical issues and factors that can affect the reliability of cholesterol results. We discuss factors that lead to impression and inaccuracy; solutions for some of the major problems; resources and techniques to help standardize cholesterol measurement; and preanalytical issues that can affect cholesterol results--i.e., patient preparation; collection, processing, storage and proper analysis of the specimen; biological and seasonal variations; age and gender; diet; alcohol consumption; weight changes; exercise; primary diseases; and infections and trauma. Many of these can be controlled by the physician, resulting in more reliable cholesterol readings under stable metabolic conditions. Accurate values will help to classify the patient's coronary heart disease risk, define appropriate treatment strategies, and simplify monitoring of dietary and/or drug intervention. |
| Accurate separation of vesicles, micelles and cholesterol crystals in supersaturated model biles by ultracentrifugation, ultrafiltration and dialysis Moschetta, A., E. R. Eckhardt, et al. (2001), Biochim Biophys Acta 1532(1-2): 15-27. Abstract: Gel filtration with bile salts at intermixed micellar/vesicular concentrations (IMC) in the eluant has been proposed to isolate vesicles and micelles from supersaturated model biles, but the presence of vesicular aggregates makes this method unreliable. We have now validated a new method for isolation of various phases. First, aggregated vesicles and - if present - cholesterol crystals are pelleted by short ultracentrifugation. Cholesterol contained in crystals and vesicular aggregates can be quantitated from the difference of cholesterol contents in the pellets before and after bile salt-induced solubilization of the vesicular aggregates. Micelles are then isolated by ultrafiltration of the supernatant through a highly selective 300 kDa filter and unilamellar vesicles by dialysis against buffer containing bile salts at IMC values. Lipids contained in unilamellar vesicles are also estimated by subtraction of lipid contents in filtered micelles from lipid contents in (unilamellar vesicle+micelle containing) supernatant ('subtraction method'). 'Ultrafiltration-dialysis' and 'subtraction' methods yielded identical lipid solubilization in unilamellar vesicles and identical vesicular cholesterol/phospholipid ratios. In contrast, gel filtration yielded much more lipids in micelles and less in unilamellar vesicles, with much higher vesicular cholesterol/phospholipid ratios. When vesicles obtained by dialysis were analyzed by gel filtration, vesicular cholesterol/phospholipid ratios increased strongly, despite correct IMC values for bile salts in the eluant. Subsequent extraction of column material showed significant amounts of lipids. In conclusion, gel filtration may underestimate vesicular lipids and overestimate vesicular cholesterol/phospholipid ratios, supposedly because of lipids remaining attached to the column. Combined ultracentrifugation-ultrafiltration-dialysis should be considered state-of-the-art methodology for quantification of cholesterol carriers in model biles. |
| Acetylated low density lipoprotein inhibits the incorporation of arachidonic acid in phospholipids with a concomitant increase of cholesterol arachidonate in rat peritoneal macrophages Pollaud, C., S. Krause, et al. (1995), Biochim Biophys Acta 1259(3): 211-9. Abstract: The aim of our work was to evaluate the influence of native low density lipoproteins (LDL) and LDL chemically modified by acetylation (acLDL) on incorporation and release of arachidonic acid (AA) in rat peritoneal macrophages. Compared to a control group without treatment, 100 micrograms/ml of acLDL for 15 h considerably increased the incorporation of 3HAA in cholesterol-ester (CE) of rat peritoneal macrophages and induced a decrease of 3H-labeled membrane phospholipids (PL). No effect was shown with LDL treatment. In the presence of acLDL, LS3251 (100 nM), an acyl-coenzyme A:cholesterol acyltransferase (ACAT) inhibitor, inhibited the 3HAA incorporation into CE in macrophages. 3HAA-prelabeled macrophages cultured for 15 h with acLDL (compared to macrophages untreated or treated with LDL) showed an increase of labeled CE and a decrease of labeled PL and of cyclooxygenase and lipoxygenase eicosanoid production. After zymosan stimulation of macrophages prelabeled with 3HAA and treated with or without LDL or acLDL, AA release and eicosanoid production increased in all groups of macrophages. The inhibition of eicosanoid production in foam cells does not seem to be linked to an inhibition of phospholipase but rather paralleled to an increase of the cholesterol 3Harachidonate. A significant portion of cellular arachidonate released from phospholipids, in particular from phosphatidylcholine, could serve as a substrate to ACAT in this foam cell. |
| Acetylcholine-Induced response of coronary resistance arterioles in cholesterol-fed rabbits Takahashi, K., M. Ohyanagi, et al. (1999), Jpn J Pharmacol 81(2): 156-62. Abstract: The extent to which reported abnormal responses of the human coronary circulation to acetylcholine in patients with hypercholesterolemia reflect endothelial injury is not clear. We used an in vitro rabbit model to determine whether these reactions involve endothelial or vascular smooth muscle dysfunction. Coronary resistance arterioles were isolated from hearts of rabbits fed 1% cholesterol to induce hypercholesterolemia or a control diet for 4 weeks. Arterioles were double cannulated with glass micropipettes and pressurized in a no-flow state. Acetylcholine contracted the arterioles in a concentration-dependent manner whether or not the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine was added. In control but not hypercholesterolemic preparations, contraction was significantly greater when endothelium was removed. In the hypercholesterolemic group, contraction significantly exceeded that in controls. In control but not high-cholesterol preparations, substance P dilated vessels with intact endothelium in a concentration-dependent manner. Addition of N(G)-monomethyl-L-arginine inhibited this response. With or without endothelium, norepinephrine contracted arterioles to a greater extent in the hypercholesterolemic group than in controls. We concluded that severe hypercholesterolemia decreased endothelially dependent factors by injuring endothelium and independently increased contractility of vascular smooth muscle. |
| Achievement of low-density lipoprotein cholesterol goals: new strategies to address new guidelines Illingworth, D. R. (2003), Cardiol Clin 21(3): 363-75. Abstract: Evidence that CHD morbidity and mortality can be reduced with reduction of LDL-C to less than 100 mg/dL (2.6 mmol/L) is rapidly accumulating. NCEP-ATP III guidelines should be considered minimal goals of therapy. Regarding the prevention and treatment of CHD, health care providers need to recognize the wide therapeutic gap between evidence-based medicine and customary clinical practice. Aggressive pharmacologic therapy is probably required to achieve optimal LDL-C levels in many hyperlipidemic patients. Novel agents, including selective cholesterol absorption inhibitors, will provide clinicians with a tool to safely and effectively target the exogenous pathway of cholesterol metabolism. Combination therapy with cholesterol-lowering agents that have complementary mechanisms of action and can be safely co-administered may be a new option to achieve broader lipid control. |
| Achievement of target plasma cholesterol levels in hypercholesterolaemic patients being treated in general practice Barter, P. J. and R. C. O'Brien (2000), Atherosclerosis 149(1): 199-205. Abstract: A total of 1028 hypercholesterolaemic men and women aged 18-75 participated in an open label, randomised, parallel group, 6-month treatment-to-target study conducted in 240 general practices throughout Australia. The study compared atorvastatin monotherapy with simvastatin monotherapy or, if necessary, with the combination of simvastatin and cholestyramine in terms of their abilities to achieve a plasma total cholesterol target of<5.0 mmol/l. The initial daily dose of each drug was 10 mg. If the target was not achieved, the dose was doubled at 6 week intervals to a maximum daily dose of 80 mg atorvastatin or 40 mg simvastatin, with the simvastatin supplemented if necessary with 4 g cholestyramine. The percentage of patients achieving the target at 10 and 20 mg doses of atorvastatin were comparable to 20 and 40 mg of simvastatin, respectively. Despite relatively high baseline levels of plasma total cholesterol (mean levels of 7.41 and 7.31 mmol/l in the atorvastatin and simvastatin groups, respectively) the majority of patients in each group achieved the plasma total cholesterol target of<5.0 mmol/l. Treatment with atorvastatin achieved the target in 83% of patients, while simvastatin (or simvastatin plus cholestyramine) achieved the target in 66% of the patients (P<0.005). The target was achieved with 10 mg atorvastatin in 38% of patients and with 10 mg simvastatin in 26% of cases (P<0.005). In patients whose baseline cholesterol levels were between 5.6 and 6.5 mmol/l, 95% of the atorvastatin group and 86% of the simvastatin group reached the target. Even with baseline cholesterol levels between 7.6 and 8.5 mmol/l, the target was reached in 78% of the atorvastatin group and 61% of the simvastatin group. It is thus realistic for general practitioners to expect the majority of their at risk patients to achieve target plasma cholesterol levels that have been shown in population studies to be associated with relatively low rates of coronary heart disease. These targets are achieved in significantly more patients and at lower mg doses with atorvastatin than simvastatin. |
| Achieving and maintaining National Cholesterol Education Program low-density lipoprotein cholesterol goals with five statins Andrews, T. C., C. M. Ballantyne, et al. (2001), Am J Med 111(3): 185-91. Abstract: PURPOSE: Most patients fail to achieve and maintain low-density lipoprotein (LDL) cholesterol goals established by the National Cholesterol Education Program (NCEP). The Atorvastatin Comparative Cholesterol Efficacy and Safety Study (ACCESS) was a randomized study comparing the efficacy and safety of five statins and their ability reduce LDL cholesterol to the NCEP target level. SUBJECTS AND METHODS: Of 7542 patients screened, 3916 hypercholesterolemic patients were randomly assigned to treatment with a statin, beginning with the lowest recommended dose (atorvastatin, pravastatin, and simvastatin, 10 mg; fluvastatin and lovastatin, 20 mg). If the NCEP target was not achieved, the dose was titrated up to the recommended maximum (atorvastatin, fluvastatin, and lovastatin, 80 mg; pravastatin and simvastatin, 40 mg). The total duration of treatment was 54 weeks. RESULTS: Atorvastatin achieved the greatest mean reduction in LDL cholesterol: 36% +/- 11% at 6 weeks (initial dose) and 42% +/- 13% at 54 weeks. More patients receiving atorvastatin at its initial dose (53%, 997 of 1888) achieved their NCEP target levels than patients receiving simvastatin (38%, 174 of 462), lovastatin (28%, 134 of 472), pravastatin (15%, 71 of 461), or fluvastatin (15%, 69 of 474) at the initial dose. Atorvastatin-treated patients were more likely to maintain their target levels from week 6 to week 54. The percent reduction in LDL cholesterol achieved at the initial dose correlated strongly with the proportion of patients who maintained their goals at 54 weeks (r = -0.84). CONCLUSION: For patients treated with statins, providing a greater margin between the NCEP target level and the achieved LDL cholesterol level enhances the likelihood of maintaining NCEP goal levels. |
| Achieving cholesterol target in a managed care organization (ACTION) trial Straka, R. J., R. Taheri, et al. (2005), Pharmacotherapy 25(3): 360-71. Abstract: STUDY OBJECTIVES: To objectively compare the results of a collaborative approach using pharmacists with the results of usual care for achieving a low-density lipoprotein cholesterol (LDL) goal of 100 mg/dl or less in outpatients with documented coronary heart disease (CHD) who are not at goal, and to document the effect on LDL after removal of such a collaborative model from the study population. DESIGN: Prospective, multiclinic, controlled study. SETTING: Four clinics of a 19-clinic staff model health maintenance organization in Minneapolis and St. Paul, Minnesota. Two clinics treated the intervention patients, two the controls; one clinic for each group was suburban, and one for each was urban. PATIENTS: Four hundred eighty-one patients aged 18 years or older with CHD and whose LDL levels were not at goal. INTERVENTION: Clinical pharmacists implemented the physician-approved care plan for each intervention patient; activities included managing lipid-lowering drug therapy and educating patients on cardiovascular risk reduction. MEASUREMENTS AND MAIN RESULTS: Primary outcomes were changes in LDL level and the proportion of patients achieving goal LDL in the intervention versus the usual care (control) group. Secondary outcomes were the sustainability of the impact observed up to 18 months after discontinuation of the intervention. Mean+/-SD baseline LDL levels were 131+/-28 and 131+/-26 mg/dl (p=NS) for the intervention and control groups, respectively. After a mean of 6.5 months follow-up, 107 (72%) patients in the intervention group and 61 (18%) patients in the control group had attained their LDL goal (p<0.001). Mean LDL levels were reduced by 35.6 mg/dl (27.5%) and 6.7 mg/dl (4.6%) in the intervention and control groups, respectively (p<0.001). When the active program was discontinued, results of the 18-month follow-up indicated that 85 (65%) intervention patients remained at goal compared with 96 (42%) controls (p<0.001). CONCLUSION: This trial provides quantitative evidence to support the effectiveness of the collaborative approach as an intervention to optimize management of patients with CHD whose LDL levels are not at goal; this approach is specifically called for in the executive summary of the National Cholesterol Education Program Adult Treatment Panel III. Furthermore, this study documents both the magnitude and sustainability of the impact collaborative care models can have in managed care environments. |
| Achieving National Cholesterol Education Program goals for low-density lipoprotein cholesterol in cardiac patients: importance of diet, exercise, weight control, and drug therapy Allison, T. G., R. W. Squires, et al. (1999), Mayo Clin Proc 74(5): 466-73. Abstract: OBJECTIVE: To determine how frequently the National Cholesterol Education Program (NCEP) goal of a low-density lipoprotein (LDL) cholesterol level of 100 mg/dL or less is achieved in clinical practice in patients with coronary artery disease and what fraction of patients can achieve this goal without drug therapy. DESIGN: We examined the results of lipid management in 152 consecutive patients who had completed cardiac rehabilitation after an acute coronary event. Patients were randomized to follow-up by specially trained nurses or by preventive cardiologists, and they were not receiving lipid-lowering drugs at the start of the study. MATERIAL AND METHODS: Patients were given aggressive diet and exercise recommendations and lipid-lowering drugs in accordance with NCEP guidelines. Follow-up was continued for a mean of 526 days after the first lipid assessment subsequent to the coronary event. Multiple logistic regression analysis was used to identify independent predictors of a final LDL cholesterol level of 100 mg/dL or less. RESULTS: Of the study group, 39% achieved the NCEP goal LDL cholesterol level of 100 mg/dL or less. Characteristics of the patients with LDL cholesterol levels of 100 mg/dL or less in comparison with those with LDL cholesterol levels of more than 100 mg/dL included a greater frequency of drug therapy (65% versus 38%), more rigorous dietary compliance, longer follow-up (586 +/- 317 days versus 493 +/- 264 days), more favorable weight change (-0.3 +/- 4.9 kg versus +1.7 +/- 5.0 kg), and more extensive weekly exercise (183 +/- 118 minutes versus 127 +/- 107 minutes). CONCLUSION: The registered nurses managed the lipids of these patients as effectively as did the preventive cardiologists. Appropriate drug therapy was the most important factor in achieving an LDL cholesterol level of 100 mg/dL or less, but 35% of patients attaining this NCEP goal were not receiving drug therapy. Exercise, dietary compliance, and weight loss were also important factors. |
| Achieving National Cholesterol Education Program goals in coronary artery disease Rondina, M. T. and J. S. Zebrack (2005), Prev Cardiol 8(1): 18-22. Abstract: National Cholesterol Education Program (NCEP) guidelines recommend low-density lipoprotein cholesterol (LDL-C) levels <100 mg/dL for patients with coronary artery disease (CAD) and lipid-lowering therapy if LDL-C remains >100-130 mg/dL after dietary intervention. Studies consistently report that the majority of CAD patients do not achieve NCEP goals in clinical practice; we sought to determine if our practice fared better. We performed a retrospective chart review of 600 CAD patients followed by cardiologists. The mean age was 69, and 66% of patients were male. Of persons with a cardiology clinic lipid profile (60%), most (76%) achieved an LDL-C <100 mg/dL; however, only 61% were treated to the NCEP secondary goal of non-HDL-C <130 mg/dL. Of patients not at an LDL-C goal, 81% were on lipid-lowering therapy, but only 18% were on maximal statin doses and 6% on combination therapy. We concluded that the majority of CAD patients have had recent lipid measurements and are treated according to NCEP guidelines, but many patients remain on suboptimal therapy. |
| Acid and bile tolerance and cholesterol removal ability of lactobacilli strains Liong, M. T. and N. P. Shah (2005), J Dairy Sci 88(1): 55-66. Abstract: Eleven strains of lactobacilli were studied for their acid and bile tolerance. Possible mechanisms of cholesterol removal by strains of lactobacilli were examined. Cholesterol assimilation as determined by the difference in cholesterol content in the medium before and after the incubation period showed that all lactobacilli strains were able to assimilate cholesterol at varying levels ranging from 12.03 to 32.25 microg/mL. Cholesterol removal was associated with growth of cultures. Binding of cholesterol to lactobacilli cells was determined using growing, heat-killed, and resting cells in phosphate buffer. Cholesterol removed by dead and resting cells ranged from 0.79 to 3.82 mg/g of dry weight compared with growing cells, which ranged from 4.53 to 16.03 mg/g of dry weight. Fatty acid methyl esters, as quantified using gas chromatography, showed changes in lipid profiles in cells grown in the presence of cholesterol compared with those grown without cholesterol. Fatty acid profiles, especially of hexadecanoic, octadecanoic, total saturated, and unsaturated acids suggested that cholesterol from the medium was incorporated into the cellular membrane. These findings suggest that strains of lactobacilli could remove cholesterol via various mechanisms and may be promising candidates for use as a dietary adjunct to lower serum cholesterol in vivo. |
| Acid and neutral lipase activity in lymphocytes of patients with increased serum cholesterol and triglyceride level Miszczuk-Jamska, B., F. Chevalier, et al. (1993), J Physiol Pharmacol 44(4): 345-50. Abstract: Acid lipase activity (ALA) and neutral lipase activity (NLA) in lymphocytes of patients with primary hyperlipidemia (hypercholesterolemia or/and hypertriglyceridemia) were compared with that of an age-matched control group (blood donors). The specificity of lipase was confirmed by the use of cardiolipin the well known activator of acidic lipase. beta-D-glucuronidase activity was used as a marker of the lysosomal release reaction. ALA (by 33%) and beta-D-glucuronidase (by 55%) activity, but not NLA in lymphocytes of the group of hyperlipidemic patients, was significantly lower when compared to the control group. A negative correlation between the serum cholesterol level and ALA, NLA and beta-D-glucuronidase release from lymphocytes of hyperlipidemic subjects was observed. The serum HDL cholesterol level was positively correlated with ALA within this group. These results suggest that the high cholesterol level in serum can unspecifically supress ALA and (to the smaller degree) NLA activity in lymphocytes of hyperlipidemic subjects. The decrease of lipase activity may promote deposition of lipids in cells and the development of atherosclerosis. The parallel decrease of beta-D-glucuronidase activity in lymphocytes of hypercholesterolemic patients suggests the impairment of immune system in hypercholesterolemia. |
| Acid sphingomyelinase-deficient macrophages have defective cholesterol trafficking and efflux Leventhal, A. R., W. Chen, et al. (2001), J Biol Chem 276(48): 44976-83. Abstract: Cholesterol efflux from macrophage foam cells, a key step in reverse cholesterol transport, requires trafficking of cholesterol from intracellular sites to the plasma membrane. Sphingomyelin is a cholesterol-binding molecule that transiently exists with cholesterol in endosomes and lysosomes but is rapidly hydrolyzed by lysosomal sphingomyelinase (L-SMase), a product of the acid sphingomyelinase (ASM) gene. We therefore hypothesized that sphingomyelin hydrolysis by L-SMase enables cholesterol efflux by preventing cholesterol sequestration by sphingomyelin. Macrophages from wild-type and ASM knockout mice were incubated with (3)Hcholesteryl ester-labeled acetyl-LDL and then exposed to apolipoprotein A-I or high density lipoprotein. In both cases, (3)Hcholesterol efflux was decreased substantially in the ASM knockout macrophages. Similar results were shown for ASM knockout macrophages labeled long-term with (3)Hcholesterol added directly to medium, but not for those labeled for a short period, suggesting defective efflux from intracellular stores but not from the plasma membrane. Cholesterol trafficking to acyl-coenzyme A:cholesterol acyltransferase (ACAT) was also defective in ASM knockout macrophages. Using filipin to probe cholesterol in macrophages incubated with acetyl-LDL, we found there was modest staining in the plasma membrane of wild-type macrophages but bright, perinuclear fluorescence in ASM knockout macrophages. Last, when wild-type macrophages were incubated with excess sphingomyelin to "saturate" L-SMase, (3)Hcholesterol efflux was decreased. Thus, sphingomyelin accumulation due to L-SMase deficiency leads to defective cholesterol trafficking and efflux, which we propose is due to sequestration of cholesterol by sphingomyelin and possibly other mechanisms. This model may explain the low plasma high density lipoprotein found in ASM-deficient humans and may implicate L-SMase deficiency and/or sphingomyelin enrichment of lipoproteins as novel atherosclerosis risk factors. |
| Acquired lecithin-cholesterol acyltransferase deficiency in nephrotic syndrome Vaziri, N. D., K. Liang, et al. (2001), Am J Physiol Renal Physiol 280(5): F823-8. Abstract: Lecithin-cholesterol acetyltransferase (LCAT) is involved in the synthesis of plasma cholesteryl esters and is pivotal in the maturation of plasma high-density lipoprotein (HDL) and conversion of HDL3 to HDL2. In nephrotic syndrome (NS), the ratio of HDL2 to HDL3 is low even though the total concentration of HDL is generally normal. We hypothesize that the reduced HDL2/HDL3 ratio in NS is due to urinary losses of LCAT, leading to plasma LCAT deficiency. To test this hypothesis, Sprague-Dawley rats were randomized to NS (given 130 mg puromycin aminonucleoside on day 1 and 60 mg ip on day 14) or control groups and were studied on day 30. To dissect the effect of proteinuria from hypoalbuminemia, a group of Nagase rats with inherited hypoalbuminemia was included. Hepatic LCAT and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA abundance and plasma and urine LCAT activity were measured. The NS group showed a fourfold rise in serum cholesterol and triglycerides, a fivefold rise in free cholesterol, and a fourfold fall in the HDL-to-total cholesterol ratio. Despite severe hypoalbuminemia, the Nagase rats showed only a mild elevation of serum cholesterol and triglycerides with a normal serum free cholesterol and HDL-to-total cholesterol ratio. The NS group exhibited a normal hepatic LCAT-to-GAPDH mRNA ratio, a marked reduction in plasma LCAT activity, and a significant increase in urinary LCAT excretion. LCAT/GAPDH mRNA and plasma and urine LCAT were normal in Nagase rats. Thus NS led to heavy urinary losses and reduced plasma concentration of LCAT, despite normal hepatic LCAT mRNA abundance. However, hypoalbuminemia, per se, without proteinuria as seen in the Nagase rats had no effect on plasma LCAT or the HDL-to-total cholesterol ratio. Therefore, proteinuria, not hypoalbuminemia, causes LCAT deficiency and a depressed HDL-to-total cholesterol ratio in NS. |
| Acridine- and cholesterol-derivatized solid supports for improved synthesis of 3'-modified oligonucleotides Reed, M. W., A. D. Adams, et al. (1991), Bioconjug Chem 2(4): 217-25. Abstract: New solid supports are described which allow the direct synthesis of oligonucleotides bearing either cholesterol or acridine at the 3'-terminus. A stereochemically defined amino diol was prepared by reduction of N-Cbz-hydroxy-L-proline. This linker molecule was first acylated with the desired conjugate molecule, then protected as the dimethoxytrityl ether. The remaining secondary hydroxyl group was succinylated and immobilized on a controlled-pore glass support. 3'-Modified oligodeoxynucleotides (ODNs) were prepared from these supports by using standard phosphoramidite coupling and deprotection conditions. A cholesterol-modified support was prepared from cholesterol chloroformate and the amino diol linker. Two types of acridine-modified solid supports were prepared from acridine tetrafluorophenyl esters with linker arms of different length. In an alternative synthesis of 3'-derivatized ODNs, these active esters were also utilized for acylation of a 3'-amine-modified ODN. A thermal denaturation study was done to determine the effect of the different linker arms on hybridization to a complementary ODN target. Facile synthesis and purification of the 3'-modified ODNs makes these functionalized solid supports especially useful for preparation of oligonucleotides bearing these and other modifications. |
| Actin and myosin isoforms in gallbladder smooth muscle following cholesterol feeding in prairie dogs Li, Y. F., R. L. Bowers, et al. (1990), Gastroenterology 99(5): 1460-6. Abstract: Gallbladder smooth muscle contractility decreases after high-cholesterol feeding in prairie dogs. This decrease is not associated with alterations in the total amounts of the contractile proteins actin and myosin. The present study was designed to determine if cholesterol feeding results in alterations in the isoforms of actin and/or myosin heavy chain in gallbladder smooth muscle. Control prairie dogs were fed a trace-cholesterol diet and test animals were fed a high (1.2%)-cholesterol diet for 8 days. Although the proportion of beta-actin was unchanged, the proportion of alpha-actin in the gallbladder was less in the animals fed the high-cholesterol diet (32.6% +/- 1.5% in the control animals and 24.6% +/- 0.4% in the diet animals). On the other hand, the proportion of gamma-actin was significantly greater in the cholesterol-fed animals. There were no significant differences in the proportions of the myosin heavy-chain isoforms between the two groups. Also, there was no change in the volume fraction of smooth muscle in the gallbladders from the two groups. Thus, cholesterol feeding induces a shift in actin isoforms at the same time that there is a decrease in contractility. Whether the altered pattern of actin isoforms is related to the functional changes remains to be determined. |