| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Complex feedback regulation of bile acid synthesis in the hamster: the role of newly synthesized cholesterol Scheibner, J., M. Fuchs, et al. (1999), Hepatology 30(1): 230-7. Abstract: Hepatic bile acid synthesis is regulated by recirculating bile acids, possibly by modulating the availability of newly synthesized and preformed cholesterol. Because data in the hamster on this mechanism are lacking, we fitted these animals with an extracorporeal bile duct and administered tritiated water intraperitoneally to label newly formed cholesterol. After interruption of the enterohepatic circulation, physiological and double-physiological doses of conjugated cholate (25 or 50 micromol/100 g. h) or of unconjugated deoxycholate (6 or 12 micromol) were infused intraduodenally for 54 hours and compared with controls. De novo and preformed cholesterol directly secreted into bile or used for cholate and chenodeoxycholate synthesis were quantitated by high-pressure liquid chromatography (HPLC)-liquid scintillation. Directly after depletion of the bile acid pool (6-9 hours) at nearly physiological conditions, chenodeoxycholate synthesis was significantly reduced by cholate and deoxycholate by up to 45% to 51%, whereas cholate formation decreased by approximately 22% during deoxycholate. This short-term effect was mainly mediated by reduced synthesis from preformed cholesterol. After long-term bile depletion (30-54 hours), bile acid synthesis returned to control levels during 25 micromol of cholate and of both deoxycholate doses. In contrast, only 50 micromol of cholate prevented derepression of bile acid synthesis. This long-term effect was mainly attributed to a diminished formation from de novo cholesterol exceeding the reduced synthesis from preformed cholesterol. In summary, short- and long-term regulation of bile acid synthesis in hamsters differs with respect to availabilities of preformed and de novo cholesterol. |
| Complex relation between increasing fat mass and decreasing high density lipoprotein cholesterol levels: evidence from a population-based study of premenopausal women Sowers, M. and C. Sigler (1999), Am J Epidemiol 149(1): 47-54. Abstract: High density lipoprotein (HDL) cholesterol levels can be used to predict cardiovascular disease risk in women. To better understand variability in HDL cholesterol levels, the authors examined the relation with three domains (body size and type, sex hormone status, and carbohydrate metabolism) in a cross-sectional population-based 1993-1994 study of 402 premenopausal women from Tecumseh, Michigan. They found that these domains explained 27% of the total variation in HDL cholesterol levels; waist-to-hip ratio was the term that explained the highest proportion of variability (6% after fat mass, sex hormone binding globulin, and insulin levels were added to the model). In analyses restricted to women whose body mass index was > or = 32 kg/m2, which constituted 19% of this population, neither body mass index nor fat mass was a significant predictor of variability in HDL cholesterol levels. Significant variables were insulin levels, waist-to-hip ratio, and smoking. This finding suggests that there is a saturation of the relation between increasing fat mass and lower HDL cholesterol levels, as evidenced by the lack of a relation between the two among the heaviest women. Meanwhile, among the heaviest women, increasing insulin levels and a higher waist-to-hip ratio remained predictors of low levels of HDL cholesterol. |
| Complexation of phosphatidylcholine lipids with cholesterol Pandit, S. A., D. Bostick, et al. (2004), Biophys J 86(3): 1345-56. Abstract: It is postulated that the specific interactions between cholesterol and lipids in biological membranes are crucial in the formation of complexes leading subsequently to membrane domains (so-called rafts). These interactions are studied in molecular dynamics simulations performed on a dipalmitoylphosphatidylcholine (DPPC)-cholesterol bilayer mixture and a dilauroylphosphatidylcholine (DLPC)-cholesterol bilayer mixture, both having a cholesterol concentration of 40 mol %. Complexation of the simulated phospholipids with cholesterol is observed and visualized, exhibiting 2:1 and 1:1 stoichiometries. The most popular complex is found to be 1:1 in the case of DLPC, whereas the DPPC system carries a larger population of 2:1 complexes. This difference in the observed populations of complexes is shown to be a result of differences in packing geometry and phospholipid conformation due to the differing tail length of the two phosphatidylcholine lipids. Furthermore, aggregation of these complexes appears to form hydrogen-bonded networks in the system containing a mixture of cholesterol and DPPC. The CH.O hydrogen bond plays a crucial role in the formation of these complexes as well as the hydrogen bonded aggregates. The aggregation and extension of such a network implies a possible means by which phospholipid:cholesterol domains form. |
| Complexes in ternary cholesterol-phospholipid mixtures McConnell, H. (2005), Biophys J 88(4): L23-5. Abstract: Recent work by Veatch and Keller has described micron-scale liquid-liquid immiscibility in giant unilamellar vesicles composed of ternary mixtures of cholesterol, dipalmitoylphosphatidylcholine (DPPC), and dioleoylphosphatidylcholine (DOPC). Significantly, they do not observe micron-scale immiscibility in any of the three corresponding binary mixtures under the same conditions. It is shown here that this unexpected result can be accounted for by the formation of a complex between cholesterol and DPPC. The complex is miscible with DPPC and cholesterol, and immiscible with DOPC. A simple, idealized thermodynamic treatment of this model leads to theoretical ternary phase diagrams that are similar to the experimental diagram reported by Veatch and Keller. The model also accounts for significant qualitative features of the deuterium NMR spectra of these mixtures in bilayers. |
| Compliance with childhood cholesterol screening among members of a prepaid health plan Bachman, R. P., E. J. Schoen, et al. (1993), Am J Dis Child 147(4): 382-5. Abstract: OBJECTIVE--To assess compliance with cholesterol screening and intervention by children who were members of a prepaid health plan in which there was no financial barrier to intervention. RESEARCH DESIGN--Children with family histories of hypercholesterolemia, coronary heart disease, and stroke were advised to have a random cholesterol test. Those with total cholesterol levels of 4.80 mmol/L (185 mg/dL) or higher were asked to return for a fasting blood test; of this group, compliant subjects with low-density lipoprotein values of 3.25 mmol/L (125 mg/dL) or higher were offered a nutrition program. SETTING--Kaiser Permanente Medical Center, Oakland, Calif. SUBJECTS AND PARTICIPANTS--The parents of 1160 children aged 2 to 18 years who had routine pediatric appointments at Kaiser Permanente Medical Center were asked to complete screening forms on family history. SELECTION PROCEDURES--Children with family histories of hypercholesterolemia, coronary heart disease, and stroke were advised to have a random cholesterol test. Subjects with total cholesterol levels of 4.80 mmol/L or higher were asked to return for a fasting test, and subjects with low-density lipoprotein levels of 3.25 mmol/L or higher were offered a nutrition program. INTERVENTIONS--Telephone call, letter, low-cholesterol diet, and nutrition program. MAIN OUTCOME MEASURES--Of the 1,160 subjects contacted, 529 (46%) had positive family histories. Of these subjects, random blood cholesterol levels were determined for 369 (70%); 160 (30%) did not comply. Ninety-three subjects had total cholesterol levels of 4.80 mmol/L or higher; of these, 35 (38%) did not comply with follow-up testing. Of the 58 compliant subjects, 25 (43%) had low-density lipoprotein values of 3.25 mmol/L or higher and were offered either a 3-week or a 6-week nutrition program. Only nine subjects (36%) enrolled; 16 (64%) did not comply. CONCLUSIONS--Parents do not comply well with a childhood cholesterol screening program that involves two blood tests and moderately intensive educational intervention. Compliance is an important component of cholesterol screening and intervention. |
| Complications of atherosclerosis in cholesterol-fed rhesus monkeys Stehbens, W. E. (1992), Arch Pathol Lab Med 116(10): 990-1. |
| Composition and functional properties of cholesterol reduced egg yolk Awad, A. C., M. R. Bennink, et al. (1997), Poult Sci 76(4): 649-53. Abstract: The composition and functional properties of cholesterol reduced egg yolk (CREY) were compared to those of control egg yolk (EY). The CREY was prepared by absorbing cholesterol with beta-cyclodextrin after dilution and dissociation of granules at pH 10.5. The CREY contained less lipid and protein and more carbohydrate and ash than EY. Egg lipids were fractionated into triglycerides, cholesterol esters, free cholesterol, phosphatidyl choline, and phosphatidyl ethanolamine. Free and esterified cholesterol in CREY were reduced by 91.6 and 94.4%, respectively. Triglycerides were the major lipid class in CREY. The CREY contained more oleic acid and less linoleic acid than the control. Protein solubility in 0.1 and 0.6 M NaCl and sponge cake volume did not differ. The composition of proteins soluble in 0.6 M NaCl in both egg preparations were similar as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The electrophoretic profiles of proteins soluble in 0.1 M NaCl were similar, except that lipovitellin form EY was insoluble under these conditions. The CREY was less yellow than EY, as indicated by beta-carotene concentrations and Hunter b values. These results suggest that beta-cyclodextrin can be used to produce a low cholesterol egg product with compositional and functional properties similar to EY. |
| Composition and immunofluorescence studies of biliary "sludge" in patients with cholesterol or mixed gallstones de la Porte, P. L., H. Lafont, et al. (2000), J Hepatol 33(3): 352-60. Abstract: BACKGROUND/AIMS: Gallbladder bile from patients with cholesterol or mixed gallstones frequently contains biliary "sludge", a suspension of cholesterol monohydrate crystals and pigment granules embedded in mucin and proteins. The composition of biliary "sludge" and the preferential localization of mucin and proteins could be an indicator for its potential role in gallstone formation. METHODS: Ultracentrifugation (100000 g/l h) was used to precipitate "sludge" from bile, and the concentration difference of its main components between native bile and ultracentrifuged bile samples was calculated. After purification of the sediment, immunolocalization was performed for the detection of mucin, IgA, albumin, aminopeptidase, and anionic polypeptide fraction using polyclonal and monoclonal antibodies. RESULTS: The amount of sludge in gallbladder bile was 4.26 mg/ml-0.78 (mean+/-SEM) in patients with cholesterol and 2.51 mg/ml+/-0.39 in patients with mixed stones and cholesterol was the main component (48.9+/-4.6% and 44.4+/-7.1%). The sediment appeared as a mixture of vesicular aggregates and pigment particles which were linked by a gel matrix of mucin containing cholesterol crystals. While anionic polypeptide fraction and aminopeptidase were associated to pigments, IgA was uniformly spread in the crystalline parts of "core-like" structures, and albumin, when it was present, appeared as randomly located small spots. CONCLUSIONS: Our study demonstrates that the cholesterol content and the distribution pattern of mucin and different proteins is similar in the sediments of biliary "sludge" to that previously shown in cholesterol and mixed gallstones. This suggests that biliary "sludge" represents an early stage of gallstone formation in these patients. |
| Composition and ultrastructure of size subclasses of normal human peripheral lymph lipoproteins: quantification of cholesterol uptake by HDL in tissue fluids Nanjee, M. N., C. J. Cooke, et al. (2001), J Lipid Res 42(4): 639-48. Abstract: Peripheral lymph lipoproteins have been characterized in animals, but there is little information about their composition, and none about their ultrastructure, in normal humans. Therefore, we collected afferent leg lymph from 16 healthy males and quantified lipids and apolipoproteins in fractions separated by high performance-size exclusion chromatography. Apolipoprotein B (apoB) was found almost exclusively in low density lipoproteins. The distribution of apoA-I, particularly in lipoprotein A-I (LpA-I) without A-II particles, was shifted toward larger particles relative to plasma. The fractions containing these particles were also enriched in apoA-II, apoE, total cholesterol, and phospholipids and had greater unesterified cholesterol-to-cholesteryl ester ratios than their counterparts in plasma. Fractions containing smaller apoA-I particles were enriched in phospholipid. Most apoA-IV was lipid poor or lipid free. Most apoC-III coeluted with large apoA-I-containing particles. Electron microscopy showed that lymph contained discoidal particles not seen in plasma. These findings support other evidence that high density lipoproteins (HDL) undergo extensive remodeling in human tissue fluid. Total cholesterol concentration in lymph HDL was 30% greater (P < 0.05) than could be explained by the transendothelial transfer of HDL from plasma, providing direct confirmation that HDL acquire cholesterol in the extravascular compartment. Net transport rates of new HDL cholesterol in the cannulated vessels corresponded to a mean whole body reverse cholesterol transport rate via lymph of 0.89 mmol (344 mg)/day. |
| Composition of plasma fatty acids and non-cholesterol sterols in anorexia nervosa Zak, A., M. Vecka, et al. (2005), Physiol Res 54(4): 443-51. Abstract: Anorexia nervosa is a model of simple starvation accompanied by secondary hyperlipoproteinemia. The pattern of plasma fatty acids influences the levels of plasma lipids and lipoproteins. The concentration of plasma lathosterol is a surrogate marker of cholesterol synthesis de novo, concentrations of campesterol and beta-sitosterol reflect resorption of exogenous cholesterol. The aim of the study was to evaluate fatty acids in plasma lipid classes and their relationship to plasma lipids, lipoproteins, cholesterol precursors and plant sterols. We examined 16 women with anorexia nervosa and 25 healthy ones. Patients with anorexia nervosa revealed increased concentrations of total cholesterol, triglycerides, HDL-cholesterol, campesterol and beta-sitosterol. Moreover, a decreased content of n-6 polyunsaturated fatty acids was found in all lipid classes. These changes were compensated by an increased content of monounsaturated fatty acids in cholesteryl esters, saturated fatty acids in triglycerides and both monounsaturated and saturated fatty acids in phosphatidylcholine. The most consistent finding in the fatty acid pattern concerned a decreased content of linoleic acid and a raised content of palmitoleic acid in all lipid classes. The changes of plasma lipids and lipoproteins in anorexia nervosa are the result of complex mechanisms including decreased catabolism of triglyceride-rich lipoproteins, normal rate of cholesterol synthesis and increased resorption of exogenous cholesterol. |
| Compound heterozygosity at the sphingomyelin phosphodiesterase-1 (SMPD1) gene is associated with low HDL cholesterol Lee, C. Y., L. Krimbou, et al. (2003), Hum Genet 112(5-6): 552-62. Abstract: Type A and B forms of Niemann-Pick disease (NPD) are lipid storage disorders caused by deficient activity of the enzyme acid sphingomyelinase (aSMase) and the resulting accumulation of sphingomyelin in tissues. In the present study, we investigated two family members who had been diagnosed with Type B NPD and who had a severe decrease in plasma high density lipoprotein cholesterol (HDL-C). The proband (a 48-year-old male) had an HDL-C of 0.30 mmol/l (12 mg/dl) and his sister had values of 0.45 mmol/l (17 mg/dl) with severe premature coronary artery disease (CAD). Hypertriglyceridemia was found in both cases. aSMase activity measured in skin fibroblasts appeared markedly depressed. The SMPD1 gene, coding for aSMase, was sequenced in affected subjects and all family members. Compound heterozygosity (DeltaR608 and R441X) was identified in both affected patients. Carriers of the DeltaR608 mutation tended to have moderately to severe decreased HDL-C levels, whereas carriers of the R441X mutation, although present only in young subjects (<20 years of age) had normal HDL-C levels. To investigate the cause of the low HDL-C level in these patients, we studied apoA-I-mediated cellular cholesterol efflux in fibroblasts. Unlike patients with Tangier disease, cholesterol efflux was found to be normal under the experimental conditions used in the present study. On the other hand, we observed a significant increase in the free cholesterol:esterified cholesterol ratio in HDL fraction from these patients and a decrease in endogenous lecithin-cholesterol acyltransferase (LCAT) activity, as determined by the fractional esterification rate. Taken together, these results suggest that (1) compound heterozygosity at the SMPD1 gene causes a severe decrease in aSMase activity and in HDL-C and increases the risk of CAD, (2) this lipoprotein abnormality is not attributable to defective cellular cholesterol efflux, (3) abnormal HDL composition might cause a decrease in LCAT activity and a lack of HDL maturation. |
| Compound heterozygosity for a structural apolipoprotein A-I variant, apo A-I(L141R)Pisa, and an apolipoprotein A-I null allele in patients with absence of HDL cholesterol, corneal opacifications, and coronary heart disease Miccoli, R., A. Bertolotto, et al. (1996), Circulation 94(7): 1622-8. Abstract: BACKGROUND: The concentration of HDL cholesterol is inversely correlated with the risk of coronary heart disease (CHD). Some rare mutations in the apolipoprotein (apo) A-I gene are associated with low levels of HDL cholesterol. Their association with cardiovascular risk is controversial. METHODS AND RESULTS: We studied the molecular defects underlying corneal opacities and absence of HDL cholesterol in three brothers and a sister. In a family study, the importance of these defects for lipid metabolism and manifestation of coronary heart disease was investigated. The frequency of these apo A-I defects was assessed by genotype and phenotype analysis of 477 DNA- and plasma samples, respectively, from the population. The four patients were compound heterozygotes for a null allele and a missense mutation in the apo A-I gene that leads to a leucine-->arginine substitution at residue 141 apo A-I(L141R)Pisa. Heterozygotes for either the null allele or the structural variant had half-normal concentrations of HDL cholesterol and apo A-I compared with unaffected family members. Apo A-I(L141R)Pisa was detected in one more unrelated subject. Coronary angiography of the four compound heterozygotes revealed the presence of CHD in all male patients, whose ages ranged between 45 and 52 years. They presented with additional risk factors, including elevated LDL cholesterol levels, obesity, and arterial hypertension. Despite complete HDL deficiency and hypercholesterolemia, CHD was absent in the 51-year-old premenopausal sister. CONCLUSIONS: Apo A-I deficiency may lead to premature atherosclerosis if present in conjunction with additional cardiovascular risk factors. |
| Compound-specific carbon isotope ratio determination of enriched cholesterol Guo, Z. K., A. H. Luke, et al. (1993), Anal Chem 65(15): 1954-9. Abstract: On-line gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) was evaluated for use in stable isotope studies of human cholesterol metabolism. Calibration curves were constructed by analyzing underivatized and TMS-cholesterol over a range of 13C abundances from natural abundance to 0.05 mol of 3,4-13Ccholesterol per mole of unlabeled cholesterol (delta 13C -24 to 27/1000). The calibration curves were highly linear (r2 = 0.99) with slopes of 0.98 and 0.88 for underivatized and TMS-cholesterol, respectively. Higher precision of 13C/12C ratio determination was obtained using TMS-cholesterol, with a detection limit (2 SD) of 0.3/1000 or 0.004 mol% of 3,4-13Ccholesterol. By comparison standard GC/MS had a detection limit of 0.06 mol% for 3,4-13Ccholesterol. A 57-day study of cholesterol elimination was conducted in one human subject with oral administration of 50 mg of 3,4-13Ccholesterol. Peak enrichment was 9/1000 above baseline (40 times the detection limit) and could be followed for 40-50 days. The results indicate that GC/C/IRMS provides 15-fold lower detection limits for 3,4-13Ccholesterol than GC/MS and is useful for human studies of cholesterol metabolism. |
| Comprehensive theory of Alzheimer's disease. The effects of cholesterol on membrane receptor trafficking Lynch, C. and W. Mobley (2000), Ann N Y Acad Sci 924: 104-11. Abstract: Neurotrophic factors (NTFs), once known for their role in development, have recently been shown to contribute to the maintenance and plasticity of the adult nervous system. This knowledge has provoked hypotheses implicating NTFs in neurodegenerative conditions, particularly Alzheimer's disease (AD). Many of these hypotheses, however, fail to place the possibility of trophic factor dysfunction in the context of recent advances in the molecular pathogenesis of AD. Most notable has been the discovery of several genetic risk factors and three causative Alzheimer's genes. Genetic advances, in turn, have not yet shed much light on an important pathological feature of AD, synaptic loss. We propose here an hypothesis based on recent cell biological research that attempts to integrate findings in these areas. Our hypothesis states that AD pathogenesis results from disruption of cholesterol uptake and metabolism and that this in turn results in abnormal trafficking of membrane proteins critical to normal neuronal function and synaptic plasticity. |
| Computation of mixed phosphatidylcholine-cholesterol bilayer structures by energy minimization Vanderkooi, G. (1994), Biophys J 66(5): 1457-68. Abstract: The energetically preferred structures of dimyristoylphosphatidylcholine (DMPC)-cholesterol bilayers were determined at a 1:1 mole ratio. Crystallographic symmetry operations were used to generate planar bilayers of cholesterol and DMPC. Energy minimization was carried out with respect to bond rotations, rigid body motions, and the two-dimensional lattice constants. The lowest energy structures had a hydrogen bond between the cholesterol hydroxyl and the carbonyl oxygen of the sn-2 acyl chain, but the largest contribution to the intermolecular energy was from the nonbonded interactions between the flat alpha surface of cholesterol and the acyl chains of DMPC. Two modes of packing in the bilayer were found; in structure A (the global minimum), unlike molecules are nearest neighbors, whereas in structure B (second lowest energy) like-like intermolecular interactions predominate. Crystallographic close packing of the molecules in the bilayer was achieved, as judged from the molecular areas and the bilayer thickness. These energy-minimized structures are consistent with the available experimental data on mixed bilayers of lecithin and cholesterol, and may be used as starting points for molecular dynamics or other calculations on bilayers. |
| Computerized tomography differentiation of pigment and cholesterol bile duct calculi Rambow, A., M. Staritz, et al. (1991), Z Gastroenterol 29(3): 137-9. Abstract: Successful oral litholytic and other non-operative therapies of gallstones require exact determination of the stone components. Since computed tomography (CT) provides highly sensitive measurement of density, we performed a study to evaluate whether CT measurement of stone density allows to predict the composition of radiolucent gallstones. 28 patients presenting with 29 radiolucent gallbladder (n = 17) or common bile duct stones (n = 12) were included. Prior to operative or endoscopic therapy the attenuation values (Hounsfield Units/HU) were assessed in vivo by CT under standardised conditions (Somatom II; 125 KV; 130 mAs). After surgical or endoscopic stone removal the concrements were dehydrated, homogenised and then analysed by infrared spectroscopy. 18 cholesterol and 11 pigment stones could be identified. The attenuation values (Hounsfield Units) of cholesterol stones amounting to 28-98 HU (48.7 +/- 4.4 HU) differed significantly (p less than 0.001) from pigment stones (90-120 HU/105.5 +/- 2.8 HU). We conclude that computed tomography provides exact discrimination between cholesterol and pigment stones in vivo. Since only cholesterol stones can be dissolved by cheno/ursodeoxycholic acid we recommend to measure the radiodensity of gallstones by CT prior to any litholytic therapy. |
| Concanavalin A-binding cholesterol crystallization inhibiting and promoting activity in bile from patients with Crohn's disease compared to patients with ulcerative colitis Keulemans, Y. C., K. S. Mok, et al. (1999), J Hepatol 31(4): 685-91. Abstract: BACKGROUND/AIMS: Crohn's disease is a risk factor for gallstone formation. In contrast, patients with ulcerative colitis have an incidence of gallstone formation comparable to the general population. The reason for this difference is not known. The aim of this study was to elucidate the factors controlling cholesterol crystallization in gallbladder bile of Crohn's disease and ulcerative colitis patients. METHODS: Gallbladder bile was obtained by aspiration during bowel resections (26 Crohn's disease patients, 20 ulcerative colitis patients). Biliary lipid composition, crystal detection time and the effect of extraction of the concanavalin A-binding fraction on crystal formation were determined. RESULTS: Cholesterol crystals were present in seven of the 26 bile samples of Crohn's disease-patients and one of the 20 ulcerative colitis patients. Four of the bile samples of Crohn's disease patients were fast nucleating. None of the 20 ulcerative colitis patients had fast nucleating bile. Lipid composition, total lipid concentration and CSI were not significantly different between the two groups. In Crohn's disease patients extraction of concanavalin A-binding fraction decreased crystallization in 10 bile samples but accelerated crystallization in one bile sample. In eight bile samples from ulcerative colitis patients crystallization increased after concanavalin A-binding fraction extraction. CONCLUSIONS: Compared to ulcerative colitis patients, gallbladder bile of Crohn's disease patients showed increased cholesterol crystallization despite comparable lipid composition and cholesterol saturation index. This difference is caused by increased cholesterol crystallization-promoting activity. Bile from ulcerative colitis patients contains a Con A-binding factor which inhibits cholesterol crystallization. |
| Concanavalin-A-extractable non-mucous glycoprotein concentrations in gallbladder bile of cholesterol gallstone patients Berghold, J., W. Swobodnik, et al. (1994), Scand J Gastroenterol 29(12): 1135-9. Abstract: BACKGROUND: The relationship between protein concentrations and the nucleation activity of bile in cholesterol gallstone patients has already been investigated. Nucleation promoters are mucins and concanavalin A (Con-A)-extractable glycoproteins. Nucleation inhibitors are apolipoproteins. We wanted to investigate whether a change in concentration of apolipoprotein A-I (Apo A-I) or Con-A in the bile of cholesterol stone carriers is dependent on the nucleation time. METHODS: Total protein was measured by fluorescence photometry, and Con-A-extractable glycoproteins were separated by their affinity to lectins and measured by photometry. Apolipoproteins were measured by radioactive competitive protein binding assay. RESULTS: The protein concentrations in our bile samples were 2.41 +/- 1.08 mg/ml for the whole group, 2.73 +/- 1.07 mg/ml for a nucleation time less than 3 days, and 2.04 +/- 1.00 for a longer nucleation time. The concentration of the Con-A fraction accounted for 0.289 +/- 0.096 mg/ml, 0.306 +/- 0.081 mg/ml, and 0.274 +/- 0.109, respectively. The Apo A-I concentration was 52 +/- 64 micrograms/ml; 50 +/- 56 micrograms/ml for a nucleation time less than 3 days and 85 +/- 133 micrograms/ml for a longer nucleation time. CONCLUSIONS: Obviously, individual protein fractions have an effect on the nucleation behaviour of gallbladder bile in cholesterol gallstone patients. |
| Concentration of plasma cholesterol in beef cows and calves, milk production and calf gain Moody, D. E., W. D. Hohenboken, et al. (1992), J Anim Sci 70(5): 1464-70. Abstract: Milk yield of 59 beef cows that calved in late September through November was measured monthly in early and late lactation and biweekly during midlactation. Milk yield was estimated by milking with a machine after over-night separation of cows from calves. Concentration of plasma cholesterol of cows and calves was measured when calves averaged 44, 93, 136, and 178 d of age (SD = 17 d). Cholesterol of calves also was measured 2 wk after weaning, when they averaged 220 +/- 2.3 d of age. Cholesterol of calves was highest at second and third samplings and dropped after weaning. The estimated intake of milkfat by calves, and to a lesser extent their intake of milk, was related positively to their plasma cholesterol as they approached weaning age. The relationship was not strong enough, however, for differences among calves in concentration of plasma cholesterol to identify accurately differences in milk yield of their dams. Within breed group, age of cow, and stage of lactation, the regression coefficients of milk yield on plasma cholesterol of cows were close to zero. The concentrations of plasma cholesterol in both cows and calves were highly repeatable, with the exception of samples that were collected when calves averaged 44 d of age. Although plasma cholesterol of calves was related positively to milk yield and milkfat yield in late lactation, the former trait was not an accurate indicator of the two latter traits. |
| Concentration of the oxygenated derivates of cholesterol in pregnant women suffering from diabetes type I Bodzek, P., A. Olejek, et al. (2002), Wiad Lek 55 Suppl 1: 50-3. Abstract: Free-radical peroxidation of cholesterol results in, among others, another products of its oxidation, called oxysterols. Scientists are still more and more interested in oxysterols, because, like the products of polyunsaturated fatty acids, show a strong biological activity, which effects physiology, pathology and pharmacology. The aim of the work was to investigate whether pre-pregnancy diabetes effects cholesterol oxidation process studied on the basis of the concentration of the chosen oxysterols. The chosen oxysterols were determined in 45 patients suffering from diabetes for various time period before pregnancy (diabetes type according to White from B to R) and in a control group (n = 27). Oxysterols (7-ketocholesterol, 7 alpha and 7 alpha-hydroxycholesterols and the sum of 5 alpha, 6 alpha and 5 beta, 6 beta-epoxycholesterols) were determined by thin-layer chromatography with densitometric detection according to the methodology which had been developed in the Chemical Department, the Silesian Medical Academy. The analysis scheme included plasma sample hydrolysis and lipid extraction, oxysterol fraction isolation by solid phase extraction (SPE), separation and identification of individual sterols by TLC technique, and densitometric quantitative analysis of the cholesterol oxidized derivatives mentioned above. We found statistically considerable differences between the concentrations of epoxycholesterol sum and 7-ketocholesterol in both groups, and the concentration was higher in the control group. While analysing the concentrations of the investigated parameters in diabetic pregnant women in II and III trimester we found a statistically considerable increase in oxysterol concentration in III trimester, compared to II trimester. The authors suggest that during complicated diabetic pregnancy the cholesterol oxidation process becomes more intensive, particularly in III trimester, compared to II trimester, both in normal pregnant women and in type I diabetic pregnant women as well. |