| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Scavenger receptor-BI inhibits ATP-binding cassette transporter 1- mediated cholesterol efflux in macrophages Chen, W., D. L. Silver, et al. (2000), J Biol Chem 275(40): 30794-800. Abstract: Scavenger receptor BI (SR-BI) facilitates the efflux of cellular cholesterol to plasma high density lipoprotein (HDL). Recently, the ATP-binding cassette transporter 1 (ABC1) was identified as a key mediator of cholesterol efflux to apolipoproteins and HDL. The goal of the present study was to determine a possible interaction between the SR-BI and ABC1 cholesterol efflux pathways in macrophages. Free cholesterol efflux to HDL was increased (approximately 2.2-fold) in SR-BI transfected RAW macrophages in association with increased SR-BI protein levels. Treatment of macrophages with 8-bromo-cAMP (cAMP) resulted in a 4.1-fold increase in ABC1 mRNA level and also increased cholesterol efflux to HDL (2.2-fold) and apoA-I (5.5-fold). However, in SR-BI transfected RAW cells, cAMP treatment produced a much smaller increment in cholesterol efflux to HDL (1.1-fold) or apoA-I (3.3-fold) compared with control cells. In macrophages loaded with cholesterol by acetyl-LDL treatment, SR-BI overexpression did not increase cholesterol efflux to HDL but did inhibit cAMP-mediated cholesterol efflux to apoA-I or HDL. SR-BI neutralizing antibody led to a dose- and time-dependent increase of cAMP-mediated cholesterol efflux in both SR-BI transfected and control cells, indicating that SR-BI inhibits ABC1-mediated cholesterol efflux even at low SR-BI expression level. Transfection of a murine ABC1 cDNA into 293 cells led to a 2.3-fold increase of cholesterol efflux to apoA-I, whereas co-transfection of SR-BI with ABC1 blocked this increase in cholesterol efflux. SR-BI and ABC1 appear to have distinct and competing roles in mediating cholesterol flux between HDL and macrophages. In nonpolarized cells, SR-BI promotes the reuptake of cholesterol actively effluxed by ABC1, creating a futile cycle. |
| Scavenger receptor-independent stimulation of cholesterol esterification in macrophages by low density lipoprotein extracted from human aortic intima Steinbrecher, U. P. and M. Lougheed (1992), Arterioscler Thromb 12(5): 608-25. Abstract: There is a growing body of evidence that suggests that modification of low density lipoprotein (LDL) in the artery wall may contribute to atherogenesis. A number of physiologically plausible modifications have been studied in vitro, including oxidation, aggregation, formation of complexes with glycosaminoglycans, and generation of LDL-immune complexes. Several studies of the properties of LDL extracted from the aortic intima have been published, but these indicate disagreement about both the nature and the extent of modification of LDL in the artery wall. The objectives of the present study were to determine the nature and extent of modification of LDL extracted from both normal and diseased human aortic intimas and to correlate this with the rate of LDL uptake in cultured cells. Analyses were performed on LDLs isolated from aortic intimas obtained at autopsy or at the time of organ harvest from 33 subjects. LDL from normal intima showed no clear evidence of oxidation but had slightly increased electrophoretic mobility compared with native plasma LDL, whereas LDL from plaques or fatty streaks exhibited variable but usually modest signs of oxidative change. Aortic LDL was more rapidly degraded by cultured macrophages than was plasma LDL and resulted in a greater stimulation of cholesterol esterification. The degree of stimulation of cholesterol esterification was correlated with the extent of modification of LDL as reflected by the degree of apolipoprotein B fragmentation. However, in all aortic LDLs the extent of oxidative change, as assessed by electrophoretic mobility or other physical parameters, was less than that required for scavenger receptor-mediated uptake. In all cases where sufficient amounts of LDL were recovered to permit degradation experiments, the uptake of aortic LDL was nonsaturable and could not be inhibited by polyinosinic acid or acetylated LDL. Chromatography on Sepharose CL-4B showed that most LDLs isolated from plaque contained a fraction that eluted in the void volume, and the size of this void peak correlated well with the stimulation of cholesterol esterification. Electron microscopy showed that the high-molecular-weight fraction contained several different types of aggregates. Some appeared to be clusters of LDL-size particles, but large vesicular structures with numerous adherent LDL particles as well as lipid droplets were also identified. These results indicate that the accelerated uptake by macrophages of LDL isolated from the arterial intima can largely be attributed to phagocytosis of LDL-containing aggregates.(ABSTRACT TRUNCATED AT 400 WORDS) |
| Scavenging and antioxidant effects of estrogen derivatives in cholesterol-fed rabbits Buko, V. U., O. Lukivskaya, et al. (2001), Adv Exp Med Biol 500: 267-70. |
| School lunch: a comparison of the fat and cholesterol content with dietary guidelines Whitaker, R. C., J. A. Wright, et al. (1993), J Pediatr 123(6): 857-62. Abstract: OBJECTIVE: To compare the fat and cholesterol content of the foods offered and selected in an elementary school lunch program with current dietary guidelines. DESIGN: For 105 school days we recorded the food items selected by elementary school students in an entire school district (262,851 meals) who were given a choice between two entrees. The nutrient content of foods was assessed with a computerized nutrient data base supplemented by the food manufacturers' data. SETTING: Sixteen elementary schools in the Bellevue (Washington) School District. PARTICIPANTS: The number of students eating school lunch averaged 2500 per day, of whom 25% were from households with incomes less than 185% of poverty. INTERVENTION: None. MAIN OUTCOME MEASURES: We determined the nutritional content of the average meal selected; the proportion of days when one of the two offered entrees met fat and cholesterol guidelines; and the proportion of children selecting the entrees that met the guidelines. RESULTS: The average lunch selected had 35.9% of calories from total fat and 12.6% from saturated fat, exceeding the guidelines of 30% and 10%, respectively. Lunch contained an average of 57 mg cholesterol (106 mg/1000 kcal) and met guidelines. One of the two daily entree choices met guidelines for both total fat and saturated fat on 20% of days, and met both fat and cholesterol guidelines on 14% of days. When available, entrees meeting the fat guidelines were chosen by 37% of students, and entrees meeting both fat and cholesterol guidelines were chosen by 34% of students. CONCLUSIONS: In this school district the average lunch selected did not meet the current guidelines for dietary fat; when given the choice, more than one third of students selected the entrees that met these guidelines. |
| Screening and intervention for cholesterol Campbell, E. and R. Samson-Fisher (1991), Aust N Z J Med 21(4): 393-5. |
| Screening for abnormal cholesterol biosynthesis in the Smith-Lemli-Opitz syndrome: rapid determination of plasma 7-dehydrocholesterol by ultraviolet spectrometry Honda, A., A. K. Batta, et al. (1997), Am J Med Genet 68(3): 288-93. Abstract: The Smith-Lemli-Opitz syndrome (SLOS) is a common condition caused by deficiency of 7-dehydrocholesterol delta 7-reductase. The syndrome can usually be diagnosed by demonstrating markedly increased plasma concentrations of the cholesterol precursor, 7-dehydrocholesterol. We describe a simple and rapid method for detection of plasma 7-dehydrocholesterol by use of ultraviolet (UV) spectrometry. Lipids were extracted from plasma by addition of ethanol and n-hexane, and the n-hexane phase was directly subjected to spectrometry. The absorption maxima characteristics of 7-dehydrocholesterol (lambda max 271, 282, and 294 nm) were observed in patients' plasma but not in controls. For quantitative measurements, absorbance at 282 nm was used. Since this absorbance is the sum of the absorbance derived from 7-dehydrocholesterol and background absorbance, the concentrations of 7-dehydrocholesterol in various plasma samples were quantified by subtracting estimated background absorbance at 282 nm from observed absorbance at 282 nm. The results correlated well with total (free plus esterified) 7-dehydrocholesterol concentrations measured by gas-liquid chromatographic method. The UV spectrometric assay was sensitive enough to detect increased 7-dehydrocholesterol in cultured skin fibroblasts from patients grown in delipidated medium. The present method will make it possible to screen plasma or fibroblasts to detect the syndrome rapidly in general clinical laboratories. |
| Screening for cardiovascular disease with cholesterol Sullivan, D. R. (2002), Clin Chim Acta 315(1-2): 49-60. Abstract: BACKGROUND: Total cholesterol (TC) and lipoprotein measurements are among the major risk factors for cardiovascular disease (CVD). ISSUES: The massive (and increasing) disease burden associated with cardiovascular disorders justifies public health measures, such as screening, which may assist with the identification and treatment of individuals who have a high risk of developing these disorders. Whole populations are placed at risk by environmental factors such as dietary habits and exercise patterns, and this may be reflected by simple tests such as TC that largely depend on dietary consumption of saturated fat and cholesterol. On the other hand, identification of high-risk individuals within populations requires more specific tests such as measurement of cholesterol in lipoprotein fractions. This recognizes that the contribution of different risk factors may vary between individuals. Dietary and pharmacological interventions, particularly those that reduce low-density lipoprotein cholesterol (LDL-C), have been shown to prevent the onset or recurrence of CVD. CONCLUSIONS: It is desirable and justifiable to try to identify high-risk patients before the onset of clinical CVD because morbidity and mortality may occur as a consequence of the initial event. The relationship between the costs and the benefits of prophylactic interventions varies according to the extent to which clinical procedures, including laboratory testing, can estimate the level of cardiovascular risk. It can be argued that inappropriate cholesterol screening may have a negative effect on health economics and patient attitudes, but these problems appear easily surmountable. Techniques that enable the preclinical detection of CVD may help the process to strike a balance between public health initiatives that reduce the environmental factors responsible for the epidemic of CVD, and the strategies that are known to reduce event rates in high-risk individuals. |
| Screening for cardiovascular risk: cost-benefit considerations in a comparison of total cholesterol measurements and two compound blood lipid indices Berg, J. E. (1995), J Cardiovasc Risk 2(5): 441-7. Abstract: BACKGROUND: Serum total cholesterol measurements have been shown to differentiate between patients with angiographically confirmed coronary artery disease and controls less well than compound indices of cardiovascular risk. Details of employees (n = 229) nominated by an occupational health service in a non-manufacturing firm were used as a starting point for calculations to compare the costs and benefits of using compound indices of cardiovascular risk with those of total cholesterol measurements alone. METHODS: Healthy employees were defined as having a low or a high risk of cardiovascular disease according to either total cholesterol level or two compound indices of blood lipid components. The compound indices were the ratio of total to high-density lipoprotein (HDL) cholesterol (the TC: HDLC ratio) and an 'atherogenic index' defined as (total cholesterol-HDL cholesterol x apolipoprotein B)/(HDL cholesterol x apolipoprotein A). If compound indices discriminate better between people at low and high risk, both the number of people given unnecessary advice on lifestyle changes or urged to take cholesterol-reducing medication and the number of people not treated because of their 'normal' cholesterol levels would be reduced. In our calculations, we assumed as 'gains' that (1) the disclosure that a total cholesterol test result is false-positive is equal to treatment costs, consultation fee and consumption foregone (i.e. resources already used on medication, services etc.) (8909 Nkr US $1 = 7 Nkr), and (2) the disclosure that a test result is false-negative is equal to consultation fee plus loss of 2 h wages (288 Nkr). RESULTS: The screening of 100,000 men and 100,000 women would incur a cost of 99 and 710 Nkr, respectively, per person assumed to benefit from extended screening using two different compound indices. Net gain would be 438 and 192 million Nkr, respectively, for the two compound indices. However, the lack of prospective data on compound indices suggests the need for cautious interpretation. CONCLUSION: Although prospective studies are needed to confirm our findings, the changes in number of false-positive and false-negative values achievable using different indices suggests a need for greater caution when using single lipid measurements as predictors of risk. The calculations of this non-prospective study indicated an increased benefit-cost ratio in assessing cardiovascular risk by using compound indices of cardiovascular risk compared with total cholesterol measurements alone. |
| Screening for coronary heart disease in elderly men based on current and past cholesterol levels Hakim, A. A., J. D. Curb, et al. (1999), J Clin Epidemiol 52(12): 1257-65. Abstract: Efficient use of cholesterol measurements to screen for coronary heart disease in the elderly is not well defined. The purpose of this report is to examine such screening based on national guidelines in a sample of older men. Since relations between cholesterol and coronary heart disease are better established in those who are younger, screening in the elderly will also consider levels of cholesterol that existed earlier in life. Data are from a prospective study of 1,170 men enrolled in the Honolulu Heart Program who were followed over a 12-year period for coronary heart disease. Follow-up began from 1980 to 1982, when cholesterol levels were determined in men who were aged 61 to 81 years. Past cholesterol levels were measured 10 years earlier (1970-1972). During the course of follow-up, coronary heart disease developed in 117 of the men. Risk of disease rose significantly (P = 0.003) with increases in past cholesterol levels (1970-1972) but not with more recent levels (1980-1982). For men with current cholesterol levels that were desirable (<5.2 mmol/L 200 mg/dl, as defined by guidelines from the National Cholesterol Education Program), disease incidence continued to rise with increasing past cholesterol levels (P<0.001). Accounting for high-density lipoprotein cholesterol and other screening factors did little to alter these findings. We conclude that desirable cholesterol levels in the elderly may not be a marker of a healthy risk profile if past cholesterol levels were high. Screening for coronary heart disease in the elderly could be improved by considering past cholesterol levels, rather than just a single measurement in later life. |
| Screening for coronary heart disease risk in the elderly: total cholesterol versus high-density lipoprotein-cholesterol Kligman, E. W. and A. J. Watkins (1991), Am J Prev Med 7(5): 263-7. Abstract: Despite recent national recommendations to use total cholesterol (TC) measures to screen patients for hyperlipidemia and coronary heart disease (CHD) risk, it is unclear how predictive this approach is for older adults, who tend to have higher high-density lipoprotein-cholesterol (HDL-C) values and therefore higher TC. We looked at lipid profiles of 190 adults with a mean age of 70.8 years (range 51 to 86 years) to determine the value of TC in predicting risk states based on HDL-C. One hundred sixty-two did not have a diagnosis of CHD; 28 had a diagnosis of CHD. Of those subjects without CHD, 13 (8.0%) with a TC under 200 mg/dL were "underscreened" since they had a low HDL-C value under 40 mg/dL. Men were three times more likely to be underscreened on the basis of TC alone. Thirty (18.5%) of the subjects were "overscreened" since they had a TC greater than or equal to 240 mg/dL and a normal HDL-C value greater than 50 mg/dL. Only women were overscreened. For those 28 subjects with CHD, TC values alone also "underscreened" 3 (10.7%) of this cohort, and "overscreened" 3 (10.7%). If a provider decides to screen for hyperlipidemia and CHD risk in older patients, a lipid profile rather than a nonfasting TC test should be ordered. Over 26% of the patients in this study would have been misclassified and inappropriately advised regarding their risk for CHD based on a TC value alone. |
| Screening for dysbetalipoproteinemia by plasma cholesterol and apolipoprotein B concentrations Blom, D. J., F. H. O'Neill, et al. (2005), Clin Chem 51(5): 904-7. |
| Screening for high blood cholesterol among RI adults Fulton, J. P. (1995), R I Med 78(3): 96-7. |
| Screening for high cholesterol Hulley, S. B. and A. L. Avins (1990), J Gen Intern Med 5(1): 88-9. |
| Screening for increased cholesterol values in blood donors Dengler, T., D. Kasulke, et al. (1995), Infusionsther Transfusionsmed 22(4): 226-31. Abstract: OBJECTIVE: In a pilot study blood donors were screened on HDL, LDL, and total cholesterol. The practicability and significance of such a screening in a blood bank should be tested. DESIGN: For this purpose, current methods to determine HDL, LDL, and total cholesterol were adapted on microtiter plates and validated. In a period of about 4 weeks all blood donors were tested for the three cholesterol parameters. SETTING: Red Cross blood bank in Baden-Baden, Germany with about 150,000 donations per year. PARTICIPANTS: The HDL, LDL, and total cholesterol results of 10,006 blood donors could be evaluated. INTERVENTIONS: None. RESULTS: The mean total cholesterol was 192 +/- 36 mg/dl, the mean HDL cholesterol 56 +/- 15 mg/dl, and a mean LDL cholesterol of 123 +/- 39 mg/dl was found. The known age-dependency of the measured cholesterol fractions could be confirmed in our blood donor population. According to the current recommendations, more than 20% of the tested blood donors need a therapy. CONCLUSIONS: The study shows that the screening of blood donors for increased total cholesterol for prevention of coronary heart disease could be done with a minimum of costs. |
| Screening for naturally occurring apolipoprotein A-I variants: apo A-I(delta K107) is associated with low HDL-cholesterol levels in men but not in women Nofer, J. R., A. von Eckardstein, et al. (1995), Hum Genet 96(2): 177-82. Abstract: Isoelectric focussing (IEF) in carrier ampholyte-generated pH gradients and hybrid isoelectric focussing (HIEF) in immobilized pH gradients under nondenaturing conditions were used in parallel to screen 5,500 plasma samples for naturally occurring variants of apolipoprotein A-I (apo A-I). The following defects were identified in four unrelated subjects heterozygous for apo A-I variants: apo A-I(delta K107)(2 x), apo A-I(K107M)(1 x), and apo A-I(E41R)(1 x). The later variant is a novel finding. Family studies did not reveal any association of apo A-I(K107M) and apo A-I(E41R) with dyslipidemia, but identified several heterozygotes for apo A-I(delta K107) who had low levels of high density lipoprotein (HDL)-cholesterol. Therefore, and since the apo A-I(delta K107) is the most frequent apo A-I variant in Germany (1: 5,000) we evaluated our data and that reported from 11 families with 32 heterozygous carriers and 30 unaffected controls. This analysis revealed that apo A-I(delta K107) is associated with lower HDL-cholesterol (-30%) and higher triglycerides (+48%) in men but not in women as compared with unaffected family members as well as with controls from the Prospective Cardiovascular Munster (PROCAM) study. Moreover, 11 of 15 male apo A-I(delta K107) heterozygotes but only 2 of 17 female apo A-I(delta K107) heterozygotes had HDL-cholesterol levels below the 20th percentile of sex-matched controls from the PROCAM study. We conclude that heterozygosity for apo A-I(delta K107) decreases HDL-cholesterol and increases triglycerides in men but not in women. |
| Screening for prostate cancer: have you had your cholesterol measured? Boyle, P. (2003), BJU Int 92(3): 191-9. Abstract: Screening for prostate cancer has become one of the most common topics of conversation at urological oncology meetings. Most people have a bias as to whether there should or should not be a national screening programme. Unfortunately there are many unanswered questions, which may or may not be possible to answer definitively. In a balanced and scholarly review of the subject, Professor Peter Boyle indicates several flaws in the agreement for screening, but feels that PSA testing will continue unabated. The authors from the University of Stellenbosch review the plentiful literature relating to testicular torsion and functional recovery. They also review the mechanism of injury and the effect on the contralateral testis. |
| Screening for prostate cancer: have you had your cholesterol measured? Schroder, F. H. (2004), BJU Int 93(3): 423-4. |
| Screening for total cholesterol. Do the National Cholesterol Education Program's recommendations detect individuals at high risk of coronary heart disease? Bush, T. L. and D. Riedel (1991), Circulation 83(4): 1287-93. Abstract: BACKGROUND. The National Cholesterol Education Program (NCEP) has provided guidelines for identification of persons at high risk of coronary heart disease (CHD) because of lipid abnormalities. These recommendations are based on total cholesterol as the initial screening tool and have become the stimulus for clinic- and community-based screening programs nationwide. However, the use of the guidelines may be problematic because individuals may have total cholesterol levels in the desirable range but low density lipoprotein (LDL) or high density lipoprotein (HDL) levels considered at high risk. This study evaluates the ability of the NCEP screening recommendations to identify correctly persons at high risk of CHD because of lipid abnormalities. METHODS AND RESULTS. Using the NCEP guidelines, we simulated a population-based screening program with data from visits 1 and 2 of the Lipid Research Clinics Program Prevalence Study. Individuals were considered to be at high risk of CHD if they had LDL levels greater than 160 mg/dl or HDL levels less than 35 mg/dl. Following the NCEP process, 21% of those with high LDL concentrations and 66% of those with low HDL concentrations would not be routinely referred for immediate treatment. Overall, 41% of those at high risk of CHD would not be promptly evaluated. The sensitivity of the guidelines for promptly identifying individuals with lipoprotein abnormalities is 59%. CONCLUSIONS. This relatively low sensitivity of total cholesterol as a screening tool should be the impetus for rethinking the screening guidelines. Specifically, the cost-benefit ratio of routine screening for lipoproteins, particularly HDL cholesterol, needs to be carefully considered. |
| Screening of cholesterol levels in middle school students at the Community of Lainate (Milan) Della Rosa, M. C., M. Colombo, et al. (1999), Pediatr Med Chir 21(2): 63-6. Abstract: An example of good integration of territorial sanitary services with hospital services. An observational study that pointed out cholesterol disorders in a pre-adolescent population of a little city next to Milan. |
| Screening of drugs inhibiting cholesterol synthesis Bibikova, M. B. (1997), Antibiot Khimioter 42(8): 21-5. Abstract: The biosynthesis of fusidin, an antibiotic of steroid structure, was used as a model of steroid synthesis. Screening of compounds modifying the fusidin synthesis included 80 strains of mycelial fungi. A high frequency of such fungal cultures was observed. 9 cultures forming compounds which inhibited the synthesis of cholesterol in the cell culture of human hepatocytes were screened. A method for biological estimation of the activity of cholesterol synthesis inhibitors was developed on rabbits with high blood levels of cholesterol. It was shown that the cholesterol synthesis inhibitors, isolated as a result of the specific screening were not toxic and markedly lowered the cholesterol blood levels. |