| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Cholesterol in bilayers of sphingomyelin or dihydrosphingomyelin at concentrations found in ocular lens membranes Epand, R. M. (2003), Biophys J 84(5): 3102-10. Abstract: Membranes of the lens of the eye of mammals have two particular characteristics, high concentrations of sphingomyelin, and dihydrosphingomyelin and cholesterol. We have studied the miscibility of cholesterol with both egg sphingomyelin and with dihydrosphingomyelin made by hydrogenation of egg sphingomyelin. At a cholesterol mol fraction of 0.5 and lower, crystallites of cholesterol are not present with either form of sphingomyelin, as observed by differential scanning calorimetry and by (13)C CP/MAS NMR. However, in the range of 0.6 to 0.8 mol fraction of cholesterol increasing amounts of crystallites form, with the amount of anhydrous cholesterol crystals formed being somewhat greater with dihyrosphingomyelin compared with sphingomyelin. Interestingly, cholesterol monohydrate crystallites formed in these two phospholipids exhibit a temperature of dehydration higher than that of pure cholesterol monohydrate crystals. These cholesterol monohydrate crystals form more rapidly and in greater amounts with the unmodified form of sphingomyelin. This difference is likely a consequence of differences at the membrane interface. The chemical shift of the (13)C of the carbonyl group, as measured by CP/MAS NMR, shows that there are differences between the two phospholipids in both the presence and absence of cholesterol. The bilayers with dihydrosphingomyelin are more hydrogen bonded. Cholesterol crystallites are known to be present in the lens of the eye. Our studies show that the ratio of sphingomyelin to dihydrosphingomyelin can affect the rate of formation of these cholesterol crystallites and thus play a role in the membrane of cells of the lens, affecting ocular function. |
| Cholesterol in childhood: friend or foe? Commentary on the article by Merkens et al. on page 726 Irons, M. B. (2004), Pediatr Res 56(5): 679-81. |
| Cholesterol in childhood: how high is OK? Recommendations for screening, case-finding and intervention Boulton, T. J., J. A. Seal, et al. (1991), Med J Aust 154(12): 847-50. Abstract: OBJECTIVE: To develop guidelines for screening and case-finding of children with raised serum cholesterol levels and to determine realistic cut-points for intervention and management. DESIGN: The percentiles for serum cholesterol selected by authoritative US bodies for intervention were applied to the available Australian data on serum cholesterol levels in children. CONCLUSION: On the basis of this information we recommend a serum cholesterol level of 4.5 mmol/L as the target ceiling for Australian children; 5.5 mmol/L as the cut-point for active dietary intervention; and 6.0 mmol/L as the cut-point for specialist referral. A dual approach to intervention is recommended: population intervention through health promotion; and at a family level case-finding with individual intervention targeted to children with a serum cholesterol level greater than 5.5 mmol/L, with emphasis on dietary change in both cases. |
| Cholesterol in condensed and fluid phosphatidylcholine monolayers studied by epifluorescence microscopy Worthman, L. A., K. Nag, et al. (1997), Biophys J 72(6): 2569-80. Abstract: Epifluorescence microscopy was used to investigate the effect of cholesterol on monolayers of dipalmitoylphosphatidylcholine (DPPC) and 1 -palmitoyl-2-oleoyl phosphatidylcholine (POPC) at 21 +/- 2 degrees C using 1 mol% 1-palmitoyl-2-12-(7-nitro-2-1, 3-benzoxadizole-4-yl)aminododecanoylphosphatidylcholine (NBD-PC) as a fluorophore. Up to 30 mol% cholesterol in DPPC monolayers decreased the amounts of probe-excluded liquid-condensed (LC) phase at all surface pressures (pi), but did not effect the monolayers of POPC, which remained in the liquid-expanded (LE) phase at all pi. At low pi (2-5 mN/m), 10 mol% or more cholesterol in DPPC induced a lateral phase separation into dark probe-excluded and light probe-rich regions. In POPC monolayers, phase separation was observed at low pi when > or =40 mol% or more cholesterol was present. The lateral phase separation observed with increased cholesterol concentrations in these lipid monolayers may be a result of the segregation of cholesterol-rich domains in ordered fluid phases that preferentially exclude the fluorescent probe. With increasing pi, monolayers could be transformed from a heterogeneous dark and light appearance into a homogeneous fluorescent phase, in a manner that was dependent on pi and cholesterol content. The packing density of the acyl chains may be a determinant in the interaction of cholesterol with phosphatidylcholine (PC), because the transformations in monolayer surface texture were observed in phospholipid (PL)/sterol mixtures having similar molecular areas. At high pi (41 mN/m), elongated crystal-like structures were observed in monolayers containing 80-100 mol% cholesterol, and these structures grew in size when the monolayers were compressed after collapse. This observation could be associated with the segregation and crystallization of cholesterol after monolayer collapse. |
| Cholesterol in elderly women Pocock, S. J. and P. T. Seed (1992), Lancet 339(8806): 1426. |
| Cholesterol in fingerstick capillary specimens can be equivalent to conventional venous measurements Warnick, G. R., E. T. Leary, et al. (1994), Arch Pathol Lab Med 118(11): 1110-4. Abstract: Current interest in coronary heart disease and cholesterol has led to the development of a new generation of compact analysis systems designed for fingerstick whole blood measurement. Since reliable classification of patients based on national cut-points for serum cholesterol concentration requires accurate results, the question whether results from fingerstick capillary specimens are equivalent to those from conventional venous-derived serum specimens, the basis for the national cut-points, is germane. Earlier studies in the literature are contradictory, with fingerstick differences ranging from 9% low to 6% high. We developed guidelines for reliable fingerstick collection and, following these guidelines, achieved results that were comparable to results derived from concurrently collected venous serum specimens. Results measured either by an accurate, standardized enzymatic assay or by the AccuMeter, a new noninstrumented device, were in close agreement with serum results, ie, within 1% and 1.7%, respectively, suggesting that fingerstick measurements are appropriate for identifying individuals with elevated cholesterol levels and monitoring their treatment. |
| Cholesterol in food and serum Keller, U. (1993), Dtsch Med Wochenschr 118(1-2): 44. |
| Cholesterol in health and disease Tabas, I. (2002), J Clin Invest 110(5): 583-90. |
| Cholesterol in infants' diet Mize, C. E. and R. Uauy (1993), Compr Ther 19(6): 267-71. |
| Cholesterol in lipid microdomains (rafts)--a new probe for cholesterol-rich membrane domains Shimada, Y. and Y. Ohno-Iwashita (2002), Seikagaku 74(7): 547-51. |
| Cholesterol in model membranes. A molecular dynamics simulation Edholm, O. and A. M. Nyberg (1992), Biophys J 63(4): 1081-9. Abstract: Molecular dynamics simulations of a model membrane with inserted cholesterol molecules have been performed to study the perturbing influence of cholesterol. In the fluid phase of a lipid bilayer at 13 mol% concentration of cholesterol, local ordering of the hydrocarbon chains is induced. This perturbation decays with the distance from the cholesterol, and the effect extends 1.25 nm. It can be monitored in several ways, e.g., by an order parameter corresponding to deuterium nuclear magnetic resonance quadrupolar splittings, by the fraction of gauche bonds, or by the local bilayer thickness. At constant surface density, the local ordering is accompanied by disordering of the bulk phase, and, consequently, the net ordering effect is small. After compressing the system laterally in accordance with experimentally known surface areas, the bulk order parameters agree with those of a pure system, and the average order parameters are in accordance with experimental data. The necessity for this lateral compression is supported by calculated lateral pressures. At lower cholesterol concentration (3%), no direct perturbing effect is observed. A smaller lateral pressure than in a pure system indicates that the system with cholesterol is expected to have a smaller surface area, which would result in an increase of the order parameters, thus accounting for the experimental observations. The lack of spatial variation is, however, puzzling and may indicate a cooperative ordering effect. |
| Cholesterol in mood and anxiety disorders: review of the literature and new hypotheses Papakostas, G. I., D. Ongur, et al. (2004), Eur Neuropsychopharmacol 14(2): 135-42. Abstract: Cholesterol plays an integral role in the structure and function of the cell membrane and may also affect neurotransmission in the central nervous system. Previous work has identified abnormalities in serum cholesterol levels in patients with mood and anxiety disorders as well as in suicidal patients. However, the biological significance of these abnormalities remains to be clarified. An understanding of how serum cholesterol relates to the pathophysiology of mood disorders may generate biological markers that predict treatment response as well as targets for novel therapeutic strategies. In this article, we review the literature studying the significance of cholesterol in mood and anxiety disorders, with an emphasis on new studies focusing on the adverse impact of hypercholesterolemia on the treatment of major depressive disorder (MDD). We then propose possible mechanisms that would account for the relationship between elevated cholesterol and treatment non-response in MDD. |
| Cholesterol in neurologic disorders of the elderly: stroke and Alzheimer's disease Reiss, A. B., K. A. Siller, et al. (2004), Neurobiol Aging 25(8): 977-89. Abstract: Mechanisms for the regulation of intracellular cholesterol levels in various types of brain and vascular cells are of considerable importance in our understanding of the pathogenesis of a variety of diseases, particularly atherosclerosis and Alzheimer's disease (AD). It is increasingly clear that conversion of brain cholesterol into 24-hydroxycholesterol and its subsequent release into the periphery is important for the maintenance of brain cholesterol homeostasis. Recent studies have shown elevated plasma concentrations of 24-hydroxycholesterol in patients with AD and vascular dementia, suggesting increased brain cholesterol turnover during neurodegeneration. The oxygenases involved in the degradation and excretion of cholesterol, including the cholesterol 24-hydroxylase and the 27-hydroxylase, are enzymes of the cytochrome P-450 family. This review focuses on the newly recognized importance of cholesterol and its oxygenated metabolites in the pathogenesis of ischemic stroke and AD. The reduction in stroke and AD risk in patients treated with cholesterol-lowering statins is also discussed. |
| Cholesterol in normal and pathological seminal plasma Valsa, J., K. P. Skandhan, et al. (1992), Panminerva Med 34(4): 160-2. Abstract: One hundred and twenty eight samples (seminal plasma) were studied for cholesterol. They included normozoospermia (44), oligozoospermia (22), oligoasthenozoospermia (34) and azoospermia (28). The cholesterol level in normal group was 61.48 mg/dl (32.5-97.5 mg/dl). Among the groups no difference was seen in cholesterol level. Correlation (r = 10.35) was existing between total spermatozoa count and the level of cholesterol in normozoospermia. A reverse pattern was seen in oligozoospermia (r = -4.04). There was no correlation present between cholesterol and spermatozoa motility in any groups studied. |
| Cholesterol in patients with coronary heart disease: how low should we go? Rubins, H. B. (1995), J Gen Intern Med 10(8): 464-71. Abstract: CLINICAL PROBLEM: To examine the evidence supporting the recent National Cholesterol Education Program (NCEP) recommendation that low to moderate levels of cholesterol should be aggressively managed in patients with coronary heart disease (CHD). METHODS: Cohort studies and clinical trials with angiographic or clinical endpoints, that included CHD patients with low to moderate levels of cholesterol, were systematically identified through a MEDLINE search and critically reviewed. SYNOPSIS: None of the cohort studies show that a moderate level of cholesterol confers significantly increased risk of CHD death, although a pooled relative risk of 1.14 (95% CI 1.08 to 1.4) suggests that there may be a slight excess risk. Of five angiographic trials of CHD patients with moderate levels of cholesterol, two demonstrated no improvement in angiographic endpoints with intensive lipid-lowering therapy and the other three are difficult to interpret since they included other interventions in addition to the cholesterol-lowering regimen. No large clinical trial with clinical endpoints has been reported for CHD patients with low to moderate levels of cholesterol. RECOMMENDATIONS: The recommendation to treat CHD patients who have low to moderate levels of cholesterol with diet or drugs is not based on convincing evidence of efficacy. This is in clear contrast to the recommendation for CHD patients with high levels of cholesterol, for whom there is definitive clinical trial evidence of benefit from cholesterol-lowering therapy. While we await clinical trial results for CHD patients with low to moderate levels of cholesterol, clinicians and patients must consider the possible disadvantages of therapy in relation to the uncertain benefit. |
| Cholesterol in peripheral vascular disease--a suitable case for treatment? Clark, A. L., J. C. Byrne, et al. (1999), Qjm 92(4): 219-22. Abstract: We assessed the prevalence of conventional risk factors for ischaemic heart disease in patients with peripheral vascular disease, and the scope for preventative treatment with lipid-lowering therapy in this group, by retrospectively reviewing 299 patients who had undergone peripheral angiography in 1996. A total of 278 patients had severe peripheral vascular disease; 44% were current smokers at the time of their angiogram, and 36% had a history of coronary artery disease (either myocardial infarction, coronary artery bypass surgery, coronary angioplasty or angina). Cholesterol had been measured in 80 (27%) patients, of whom 26 (9%) were receiving treatment for hypercholesterolaemia. Patients with a history of ischaemic heart disease were more likely to have had their cholesterol measured (50% vs. 15%; p < 0.001). Hypertension (defined as systolic > 160 mmHg or diastolic > 90 mmHg) was present in 44%. There was no difference in the distribution of risk factors between those with and those without known ischaemic heart disease. There is a high prevalence of modifiable risk factors for coronary disease in patients with severe peripheral vascular disease. Effective prevention is available for coronary artery disease, but we found low levels of treatment. There is considerable scope for intervention to reduce the risk of coronary disease in such patients. |
| Cholesterol in perspective Forge, B. H. (1999), Med J Aust 170(8): 385-90. Abstract: Patients with known heart disease should be treated--others should be considered on the basis of their absolute risk profile and not just their cholesterol level. |
| Cholesterol in pleural effusions: a differential diagnostic aid Hamm, H., B. Pfalzer, et al. (1990), Pneumologie 44 Suppl 1: 180-1. Abstract: In this prospective study, 70 patients with pleural effusions were investigated; the underlying disease was identified in 62 of these cases. Employing pre-defined criteria, 31 effusions were identified to be transudates, and 31 exsudates. The total protein, LDH and cholesterol were determined in order to establish their significance for the differentiation between transudates and exsudates. In 11-15% of the cases, the parameters protein and LDH led to a false classification of the effusions. The mean cholesterol concentration in malignant effusions was 94 mg/dl; in inflammatory effusions 76 mg/dl, and in transudates 30 mg/dl. By employing a threshold of 60 mg/dl to distinguish between transudates and exsudates, it proved possible to correctly classify 95% of the effusions. Lipoprotein studies using density gradient analysis revealed that the effusion cholesterol arises out of the serum, and is not a consequence of local cellular degeneration. Our results indicate that the determination of cholesterol levels is a simple and inexpensive method for distinguishing between transudate and exsudate. |
| Cholesterol in pleural fluid. Its usefulness in differentiating between exudates and transudates Sanchez Hernandez, I., P. Ussetti Gil, et al. (1994), Arch Bronconeumol 30(5): 240-4. Abstract: To analyze the usefulness of cholesterol levels in the differentiation of exudates and transudates. A 3.5-year prospective study of 170 patients with pleural discharge. Clinical microbiological and cyto-histological criteria were used for diagnosis. Exudates were classified by Light's criteria, by cholesterol > or = 45 mg/dl in pleural liquid, by a cholesterol in pleural liquid/cholesterol in serum quotient > or = 0.3 and by a finding of both LDH and cholesterol in pleural fluid. These criteria were compared with the final etiological diagnosis. Only pleural discharges with confirmed etiological diagnoses were analyzed. In the 130 pleural discharges for which certain etiological diagnoses were obtained, 33 were transudates and 97 were exudates. Light's criteria allowed accurate classification of 92 (95%) of the 97 exudates and 30 (91%) of the 33 transudates. The cholesterol in pleural liquid/cholesterol in serum quotient was the most productive and useful parameter (96% sensitivity, 97% specificity), better than pleural fluid cholesterol and the Light's criteria. The association of LDH and pleural fluid cholesterol classified 100% of the exudates, with efficacy similar to that of Light's criteria. The cholesterol in pleural fluid/serum quotient was the most useful biochemical variable. Cholesterol levels were about as useful as Light's criteria. The association of LDH and cholesterol allows us to bypass blood analyses for the diagnosis of exudates. |
| Cholesterol in remnant like lipoprotein Yamada, N. (1999), Nippon Rinsho 57 Suppl: 24-7. |