| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Simultaneous determination of cholesterol and cholestanol in human serum by high-performance liquid chromatography using 3-(5,6-methylenedioxy-2-phthalimidyl)benzoyl azide as precolumn fluorescent labelling reagent Tsuruta, Y., T. Teranishi, et al. (1993), J Chromatogr 617(2): 213-20. Abstract: A fluorescent labelling reagent, 3-(5,6-methylenedioxy-2-phthalimidyl) benzoyl azide, designed for the determination of alcohols by precolumn high-performance liquid chromatography, has been applied to the simultaneous determination of cholesterol and cholestanol in human serum. The reagent reacts with cholesterol and cholestanol at 140 degrees C for 10 min to produce the fluorescent derivatives, which can be separated on a reversed-phase column with acetonitrile-ethanol-water (60:35:7.5, v/v) as eluent. The detection limits for cholesterol and cholestanol were 45 and 50 fmol per injection (20 microliters), respectively. The values of cholesterol and cholestanol in normal human sera were 135-212 mg/dl and 137-928 micrograms/dl, respectively. |
| Simultaneous determination of coenzyme Q10, cholesterol, and major cholesterylesters in human blood plasma Gay, C. A. and R. Stocker (2004), Methods Enzymol 378: 162-9. |
| Simultaneous determination of hydroperoxides of phosphatidylcholine, cholesterol esters and triacylglycerols by column-switching high-performance liquid chromatography with a post-column detection system Akasaka, K., H. Ohrui, et al. (1993), J Chromatogr 622(2): 153-9. Abstract: A method for the simultaneous determination of hydroperoxides of phosphatidylcholines (PC), triacylglycerols (TG) and cholesterol esters (CE) has been developed. A sample was separated into a combined TG and CE hydroperoxides fraction and a PC hydroperoxides fraction on a short silica column. The fractions were introduced into an ODS column and another silica column by a valve-switching device. The PC hydroperoxides were monitored by a post-column detection system with diphenyl-1-pyrenylphosphine, and the TG and CE hydroperoxides were monitored by another switching device. With this system, the hydroperoxides were determined at the picomole level within 32 min. Their detection limits were 2-4 pmol at a signal-to-noise ratio of 3, and the relative standard deviations of the peak areas were 1.6-3.1%. This method was successfully applied to determine lipid hydroperoxides in human plasma. |
| Simultaneous determination of mevalonate and 7 alpha-hydroxycholesterol in human plasma by gas chromatography-mass spectrometry as indices of cholesterol and bile acid biosynthesis Yoshida, T., A. Honda, et al. (1993), J Chromatogr 613(2): 185-93. Abstract: A very sensitive and specific method for the simultaneous determination of mevalonate and 7 alpha-hydroxycholesterol in human plasma is described. The assay is based on isotope dilution mass spectrometry: the extracts from plasma were treated with benzylamine followed by dimethylethylsilylimidazole, then the resulting dimethylethylsilyl ether derivatives of mevalonylbenzylamide and 7 alpha-hydroxycholesterol were determined by gas chromatography-mass spectrometry using high-resolution selected-ion monitoring. Simple regression analysis revealed significant correlations between the plasma level of mevalonate and the hepatic activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (EC 1.1.1.34) (r = 0.83, P < 0.01) and between the plasma level of free 7 alpha-hydroxycholesterol and the hepatic activity of cholesterol 7 alpha-hydroxylase (EC 1.14.13.7) (r = 0.76, P < 0.05). |
| Simultaneous determination of plasma mevalonate and 7alpha-hydroxy-4-cholesten-3-one levels in hyperlipoproteinemia: convenient indices for estimating hepatic defects of cholesterol and bile acid syntheses and biliary cholesterol supersaturation Shoda, J., J. Miyamoto, et al. (1997), Hepatology 25(1): 18-26. Abstract: The high prevalence of cholesterol gallstone disease in hypertriglyceridemic patients may be associated with frequent metabolic defects in cholesterol and bile acid syntheses and in the concomitant formation of bile supersaturated with cholesterol. This study had the two aims: 1) to assess whether the defects as well as the degree of biliary cholesterol supersaturation in patients with hyperlipoproteinemia (HLP) can be estimated by the simultaneous determination of plasma mevalonate (MVL) and 7alpha-hydroxy-4-cholesten-3-one (C4); and 2) to assess the possible application of an estimated cholesterol saturation index (CSIE) as a means of evaluating the clinical effects of simvastatin on biliary lipid composition. Biliary cholesterol supersaturation was observed in patients with both IIa and IV HLP types. Consistent with the high activity and steady-state messenger RNA level of 3-hydroxy-3 methylglutaryl coenzyme A (HMG-CoA) reductase, plasma MVL was significantly higher in 86 patients with HLP (38 type IIa, 44.1 +/- 2.4 nmol/L and 48 type IV, 56.7 +/- 2.3; P <.01) than in 41 normolipidemic subjects (34.2 +/- 1.5), closely correlating with the molar percentage of cholesterol in bile (r =.61, P =.0001; n = 86). On the other hand, consistent with the high activity and messenger RNA level of cholesterol 7alpha-hydroxylase, plasma C4 was significantly higher in patients with HLP (type IIa, 28.8 +/- 2.3 nmol/L and type IV, 38.3 +/- 2.7; P <.01) than in normolipidemic subjects (17.4 +/- 1.5). Plasma C4 was closely correlated with plasma MVL (r =.40, P =.0001; n = 86), but was inversely correlated with the molar percentage of bile acids in bile (r =.49, P =.0001; n = 86). Assuming that cholesterol supersaturation in patients with HLP may be governed by both an enhanced cholesterol secretion (closely reflected by plasma MVL) and a decreased secretion of bile acids (closely reflected by plasma C4), the multivariate linear regression-analyses revealed that an index defined as estimated CSI (CSIE) (%) in patients with HLP was given by the following equation using plasma MVL and C4 (nmol/L): CSIE = 1MVL + 0.7C4 + 44.4. Biliary cholesterol supersaturation in patients treated with simvastatin improved in a manner parallel to the time course of decreases in plasma MVL and C4. The CSIE before and at the end of treatment were correlated with biliary CSI. These results indicate that defects of hepatic cholesterogenesis, and bile acid synthesis, and the degree of biliary cholesterol supersaturation in patients with HLP can be estimated exactly by the simultaneous determination of plasma MVL and C4; furthermore CSIE may be adopted for clinical use as a convenient index of biliary CSI. |
| Simultaneous HPLC analysis of alpha-tocopherol and cholesterol in fresh pig meat Cayuela, J. M., M. D. Garrido, et al. (2003), J Agric Food Chem 51(5): 1120-4. Abstract: A method has been developed for simultaneously determining alpha-tocopherol and cholesterol in fresh pig meat by HPLC. It allows a reduction in the number of analyses and brings savings in time and materials. The unsaponifiable fraction is extracted following the modified method of Liu et al. (Liu, Q.; Scheller, K. K.; Schaefer, D. M. Technical note: A simplified procedure for vitamin E determination in beef muscle. J. Anim. Sci. 1996, 74, 2406-2410). The modifications introduced are the use of nitrogen atmosphere during the extraction, the addition of an antioxidant in the organic extraction phase, and the use of alpha-tocopherol itself as an internal standard. There is then a chromatographic analysis which allows the separation of the two compounds in question. To identify and quantify, two different detectors are used in series: the first is a fluorescence detector (alpha-tocopherol), and the second is a light-scattering detector (cholesterol). The technique shows sufficient sensitivity to determine the normal levels of alpha-tocopherol and cholesterol in meat, with recovery percentages of 78% and 97%, respectively. The average amount of alpha-tocopherol and cholesterol in samples from pig Longissimus dorsi muscle analyzed using this method is 1.8 and 620 mg/kg of fresh meat, respectively. |
| Simultaneous liquid chromatographic determination of cholesterol, phytosterols and tocopherols in foods Indyk, H. E. (1990), Analyst 115(12): 1525-30. Abstract: A method is described for the simultaneous determination of cholesterol, phytosterols and tocopherols in dairy and non-dairy high-performance liquid chromatography. A facile saponification and extraction scheme is completed rapidly within a single reaction tube. Clean-up is not required, with analysis completed by one of two alternative reversed-phase approaches. Sterols are monitored by short-wave ultraviolet spectrophotometry, and tocopherols by means of a series fluorescence detector. Cholesterol is resolved from the principal plant phytosterols, while the tocopherol congeners are well separated, thereby offering complementary information regarding source-lipid composition in foods under regulatory quality-control conditions. Squalene, an essential metabolic sterol precursor, can also be determined concurrently at the same viewing wavelength. |
| Simultaneous lowering of serum phosphate and LDL-cholesterol by sevelamer hydrochloride (RenaGel) in dialysis patients Wilkes, B. M., D. Reiner, et al. (1998), Clin Nephrol 50(6): 381-6. Abstract: The aim of the current investigation was to study the effects of sevelamer hydrochloride (RenaGel) on serum phosphate, intact parathyroid hormone levels (iPTH), and lipid profiles in stable hemodialysis patients. Hemodialysis patients maintained on calcium containing phosphate binders were enrolled in this study. Following two weeks of washout of the phosphate binders, serum phosphate rose from 6.4 +/- 0.6 to 10.5 +/- 0.7 mg/dl (p <0.001). After 8 weeks of titration with sevelamer hydrochloride, serum phosphate fell by 4.5 +/- 0.3 to 6.3 +/- 0.7 mg/dl (p <0.0001). Serum calcium levels fell during washout (9.8 +/- 0.4 to 8.9 +/- 0.3 mg/dl, p <0.004) and were unaffected by sevelamer hydrochloride. Sevelamer hydrochloride administration was associated with a 23.0 +/- 3.1% fall in total cholesterol, a 35.9 +/- 3.0% fall in LDL cholesterol, and a 35.2 +/- 5.3% fall in the LDL:HDL cholesterol ratio (p <0.001). There was no change in HDL cholesterol, triglycerides or the concentration of fat soluble vitamins. Sevelamer hydrochloride is a well tolerated alternative to calcium or aluminum containing phosphate binders and may offer an advantage to patients who become hypercalcemic on calcium-containing antacids and vitamin D supplementation. Furthermore, sevelamer hydrochloride lowers LDL cholesterol without affecting HDL cholesterol. The potential usefulness of the lipid lowering effects of sevelamer hydrochloride needs to be determined in additional prospective studies. |
| Simultaneous microanalysis of biliary cholesterol, bile acids and fatty acids in lecithin using capillary column gas chromatography: an advantage to assess bile lithogenecity Tazuma, S., S. Hatsushika, et al. (1994), J Chromatogr B Biomed Appl 653(1): 1-7. Abstract: Simultaneous determination of biliary lipids was performed by alkaline hydrolysis, the formation of the methyl ester derivatives of fatty acids that are constituents of phospholipids and of the acetylated methyl ester derivatives of bile acids, and subsequent analysis by capillary column gas chromatography. Complete separation and satisfactory recovery of cholesterol, bile acids, and fatty acids were achieved. Also, the accuracy of the calculation of the bile cholesterol saturation index was enhanced by computation. Since the degree of acyl chain unsaturation affects the cholesterol-holding capacity in vesicles, this method provides a unique insight into bile metastability by the quantitative assessment of fatty acids in lecithin. |
| Simultaneous patient-side measurement of hemoglobin, glucose, and cholesterol in finger-stick blood Sterling, B., T. Kiang, et al. (1992), Clin Chem 38(9): 1658-64. Abstract: We describe a multianalyte assay system for patient-side use comprising single-use plastic cartridges and a small monitor. Hemoglobin, glucose, and cholesterol can be simultaneously measured in 3 min in an unmeasured volume of blood. The sample is drawn by capillary action into four channels for delivery to assay-specific stacks containing a set of closely apposed layers. The distal layer is a membrane that acts as the optical surface for reflectance optics. For glucose and cholesterol assays, erythrocytes are removed by a fibrous filter layer and oxidase-peroxidase chemical reactions contained in the optical membrane generate a colored product. For hemoglobin measurement, blood is lysed by detergent contained in a porous disk. The amount of color reaching the optical membrane is measured by fiber optics. To ensure fail-safe operation, sensors verify sample sufficiency and degree of hemolysis. The assays perform comparably with laboratory methods. |
| Simultaneous quantification of several cholesterol autoxidation and monohydroxylation products by isotope-dilution mass spectrometry Breuer, O. and I. Bjorkhem (1990), Steroids 55(4): 185-92. Abstract: An assay based on isotope-dilution mass spectrometry with deuterium-labeled internal standards was developed for simultaneous quantification of cholest-5-ene-3 beta,7 alpha-diol (7 alpha-hydroxycholesterol), cholest-5 beta,6 beta-epoxy-3 beta-ol (cholesterol-5 beta,6 beta-epoxide), cholest-5 alpha,6 alpha-epoxy-3 beta-ol (cholesterol-5 alpha,6 alpha-epoxide), cholest-5-en-7-one-3 beta-ol (7-oxocholesterol), cholestane-3 beta,5 alpha,6 beta-triol, cholest-5-ene-3 beta,25-diol (25-hydroxycholesterol), and cholest-5-ene-3 beta,26-diol (26-hydroxycholesterol) in one single serum sample. Recovery experiments and replicate analyses showed that the assay was sufficiently sensitive, accurate, and precise. The concentrations of the listed compounds in sera from 19 healthy subjects were determined and are presented. |
| Simvastatin (40 mg/day) in patients with hereditary hypercholesterolemia: effect on high density lipoprotein cholesterol Susekov, A. V., E. Solov'eva, et al. (2002), Kardiologiia 42(12): 38-41. Abstract: AIM: To study effect of simvastatin of the level of high density lipoprotein (HDL) cholesterol (CH). MATERIAL AND METHODS: Simvastatin (40 mg/day) was given for 3 months to 15 patients (3 men, 12 women, mean age 56-/+10.3 years) with hereditary type II hypercholesterolemia after washout from lipid lowering therapy. Initial level of HDL CH was below and above 1.0 mmol/l in 7 and 8 patients, respectively. Blood lipids, activity of liver enzymes and creatine kinase were determined after 1 and 3 months of therapy with simvastatin. Safety and tolerability of simvastatin were also studied. RESULTS: Simvastatin was well tolerated. In 1 patient the drug was stopped because of pain in the liver and nausea. In patients with initially low HDL CH levels of total and low density lipoprotein (LDL) CH significantly decreased by 29.6 and 36.8%, respectively, after 3 months, while level of HDL CH increased by 20% after 1 month of therapy. In patients with initially normal HDL CH levels of total and LDL CH significantly decreased by 31.1 and 32.6%, respectively, while those of triglycerides and HDL CH did not change. CONCLUSION: In patients with hereditary hypercholesterolemia 40 mg/day of simvastatin besides pronounced lowering of LDL CH level caused significant increase of HDL CH (up to 20% in 1 month) in patients with initially low level of this parameter. |
| Simvastatin effects on a human lung carcinoma and cholesterol homeostasis of host and non-host mice Polo, M. and M. G. de Bravo (2001), Arch Physiol Biochem 109(5): 435-40. Abstract: In order to investigate the effect of a competitive inhibitor of the HMG-CoA reductase on tumor growth and cholesterol homeostasis of host and non-host mice, we maintained a human lung mucoepidermoid carcinoma (HLMC) in nude mice, treating these animals with Simvastatin for 33 days. The drug increased the total activity of hepatic HMG-CoA reductase without affecting the cholesterolemia. Non-treated host animals presented lower serum, tissue and microsomal hepatic cholesterol than non-host animals. These differences disappeared when animals were treated with Simvastatin, though the induction of the reductase activity at mid-dark was higher in non-host than in host animals. Simvastatin produced no significant effects on both final tumor volume and body weight. Synthesis and cholesterol homeostasis restoration induced by liver and tumoral reductase would account for no effect on the HLMC growth after a long treatment with Simvastatin. |
| Simvastatin has anti-inflammatory and antiatherosclerotic activities independent of plasma cholesterol lowering Sparrow, C. P., C. A. Burton, et al. (2001), Arterioscler Thromb Vasc Biol 21(1): 115-21. Abstract: Inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, such as simvastatin, lower circulating cholesterol levels and prevent myocardial infarction. Several studies have shown an unexpected effect of HMG-CoA reductase inhibitors on inflammation. Here, we confirm that simvastatin is anti-inflammatory by using a classic model of inflammation: carrageenan-induced foot pad edema. Simvastatin administered orally to mice 1 hour before carrageenan injection significantly reduced the extent of edema. Simvastatin was comparable to indomethacin in this model. To determine whether the anti-inflammatory activity of simvastatin might affect atherogenesis, simvastatin was tested in mice deficient in apoE. Mice were dosed daily for 6 weeks with simvastatin (100 mg/kg body wt). Simvastatin did not alter plasma lipids. Atherosclerosis was quantified through the measurement of aortic cholesterol content. Aortas from control mice (n=20) contained 56+/-4 nmol total cholesterol/mg wet wt tissue, 38+/-2 nmol free cholesterol/mg, and 17+/-2 nmol cholesteryl ester/mg. Simvastatin (n=22) significantly (P<0.02) decreased these 3 parameters by 23%, 19%, and 34%, respectively. Histology of the atherosclerotic lesions showed that simvastatin did not dramatically alter lesion morphology. These data support the hypothesis that simvastatin has antiatherosclerotic activity beyond its plasma cholesterol-lowering activity. |
| Simvastatin increases fibrinolytic activity in human peritoneal mesothelial cells independent of cholesterol lowering Haslinger, B., M. F. Goedde, et al. (2002), Kidney Int 62(5): 1611-9. Abstract: BACKGROUND: The continuous physical and chemical irritation of the peritoneum in peritoneal dialysis patients can result in a nonbacterial serositis with increased fibrin deposition, thus promoting peritoneal fibrosis and adhesion development. By expressing the fibrinolytic enzyme tissue-type plasminogen activator (t-PA) and its specific inhibitor, plasminogen activator inhibitor-1 (PAI-1), human peritoneal mesothelial cells (HMC) play an important role in regulating peritoneal fibrinolysis. METHODS: Cultured HMC were used to examine the effect of a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, simvastatin, on the expression of t-PA and PAI-1. Antigen concentrations in the cell supernatants were measured by ELISA and Northern blot analysis was conducted for mRNA expression. RESULTS: Simvastatin time- and concentration-dependently increased t-PA and decreased PAI-1 synthesis, reaching maximal effects after 48 hours, when simvastatin (1 micromol/L) increased t-PA levels 5.1 +/- 0.1-fold and suppressed PAI-1 levels 2.6 +/- 0.2-fold. This was accompanied by a twofold increase in mesothelial cell-associated t-PA activity. Qualitatively similar results were obtained in cultured human endothelial cells, but the effects were less pronounced and required higher simvastatin concentrations. Northern blot analysis revealed that the action of simvastatin on t-PA and PAI-1 expression in HMC can be explained by parallel changes in t-PA and PAI-1 mRNA. The effects of simvastatin were prevented in the presence of mevalonate and geranylgeraniol, suggesting that the effect of simvastatin on t-PA and PAI-1 synthesis is mediated through geranylgeranyl-modified intermediates. Experiments using specific inhibitors of geranylgeranylated Rho GTPases excluded a role of members of this family of small GTP-binding proteins in simvastatin action in HMC. The effects of simvastatin on t-PA and PAI-1 expression as well as on cell shape were completely mimicked by cytochalasin D, a disrupter of cellular actin filaments, but not by colchicine, a disrupter of microtubules. CONCLUSIONS: In conclusion, the cholesterol-lowering drug simvastatin is an effective stimulator of local peritoneal fibrinolytic activity, as it increases t-PA and decreases PAI-1 production in mesothelial cells by a mechanism involving geranylgeranyl-modified intermediates and actin skeleton perturbation. These results provide a new rationale to prevent peritoneal fibrin deposition and adhesion development in peritoneal dialysis patients. |
| Simvastatin inhibits myointimal hyperplasia following carotid artery injury in cholesterol-fed rabbits Dol, F., A. Mares, et al. (1996), Blood Coagul Fibrinolysis 7(8): 772-8. Abstract: The effect of simvastatin, a potent inhibitor of 3-hydroxy 3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) was evaluated in an experimental model of myointimal hyperplasia in cholesterol-fed rabbits. Myointimal hyperplasia was induced by an air-drying injury of the left carotid artery followed by a 2%-cholesterol diet for 14 days. A 2-week oral treatment with simvastatin (6 mg/kg/day, p.o.) significantly lowered the circulating levels of cholesterol and triglycerides (41% and 49% inhibition respectively) as well as the low density lipoprotein (LDL)-cholesterol and high density lipoprotein (HDL)-cholesterol levels. Simvastatin also strongly affected the uptake of cholesterol in the arteries occurring as a consequence of vascular injury (44% inhibition, P < 0.001). Morphometric analysis revealed that both the intima and the media areas increased substantially 2 weeks after the lesion and showed a considerable smooth muscle cell accumulation in the neointima together with the presence of numerous foam cells. A 16-day oral treatment with simvastatin strongly reduced smooth muscle cells hyperplasia occurring in both the media and the intima following deendothelialization (19% and 60% inhibition respectively) suggesting that simvastatin may be a useful inhibitor of restenosis which occurs following vascular injury. |
| Simvastatin lowers C-reactive protein within 14 days: an effect independent of low-density lipoprotein cholesterol reduction Plenge, J. K., T. L. Hernandez, et al. (2002), Circulation 106(12): 1447-52. Abstract: BACKGROUND: The early response of C-reactive protein to initiation of a hydroxymethylglutaryl coenzyme A reductase inhibitor (statin) is not known. The purpose of this study was to determine the rate at which highly sensitive C-reactive protein (hsCRP) levels change after initiation of simvastatin and whether this occurs independently of the change in LDL cholesterol. METHODS AND RESULTS: The study was a crossover, double-blind design including 40 subjects with elevated LDL cholesterol. Subjects were randomly assigned to 1 of 2 groups: simvastatin 40 mg for 14 days, then placebo for 14 days, or placebo first, then simvastatin. Simvastatin decreased LDL cholesterol by 56+/-4 mg/dL (P<0.0001) at day 7 and by an additional 8+/-3 mg/dL (P=0.02) at day 14. Baseline log(hsCRP) levels were similar in the 2 groups. By day 14, log(hsCRP) was significantly lower in patients on simvastatin when compared with placebo (P=0.011). Although there was no significant difference in fibrinogen levels, simvastatin produced a modest increase in loglipoprotein(a) (P=0.03) at days 7 and 14. There were no relationships between the decrease in LDL cholesterol and the decrease in hsCRP. CONCLUSIONS: Simvastatin lowers hsCRP by 14 days, independent of its effect on LDL cholesterol. This rapid impact of a statin on hsCRP has potential implications in the management of acute coronary syndromes. |
| Simvastatin-induced decrease in the transfer of cholesterol esters from high density lipoproteins to very low and low density lipoproteins in normolipidemic subjects Ahnadi, C. E., F. Berthezene, et al. (1993), Atherosclerosis 99(2): 219-28. Abstract: Hyperlipidemic patients often have an accelerated esterified cholesterol transfer (ECT) from high density lipoproteins (HDL) to very low (VLDL) and low density lipoproteins (LDL). We investigated the effect of simvastatin on ECT in twelve normolipidemic subjects. After 6 weeks of simvastatin administration, ECT was decreased by 23%. To determine the mechanism of action of simvastatin, we measured ECT in different recombination experiments, using an isotopic assay in which the transfer of labelled EC from HDL to VLDL/LDL was determined. When HDL of the treated subjects were incubated with VLDL/LDL and CETP fractions isolated from control plasma, no effect of simvastatin was observed, indicating that the drug did not alter the HDL-dependent ECT. This might be expected since simvastatin induced only minor modifications of HDL structure. When HDL and VLDL/LDL of control plasma were incubated with CETP fractions of the treated subjects, a clear reduction of ECT occurred after simvastatin administration. The decrease of plasma transfer activity was correlated to that of CETP concentration and accounted for the simvastatin-induced lowering of ECT. The diminution of plasma CETP was correlated to that of the apo B-containing lipoproteins concentration. This finding confirms previous reports suggesting a relationship between LDL level and CETP activity. In conclusion, our work shows that simvastatin administration results in a decrease of ECT and that this effect occurs through a lowering of plasma CETP activity. |
| Single and interacting QTLs for cholesterol gallstones revealed in an intercross between mouse strains NZB and SM Lyons, M. A., R. Korstanje, et al. (2005), Mamm Genome 16(3): 152-63. Abstract: Quantitative trait locus (QTL) mapping was employed to investigate the genetic determinants of cholesterol gallstone formation in a large intercross between mouse strains SM/J (resistant) and NZB/B1NJ (susceptible). Animals consumed a gallstone-promoting diet for 18 weeks. QTL analyses were performed using gallstone weight and gallstone absence/presence as phenotypes; various models were explored for genome scans. We detected seven single QTLs: three new, significant QTLs were named Lith17 chromosome (Chr) 5, peak=60 cM, LOD=5.4, Lith18 (Chr 5, 76 cM, LOD=4.3), and Lith19 (Chr 8, 0 cM, LOD=5.3); two confirmed QTLs identified previously and were named Lith20 (Chr 9, 44 cM, LOD=2.7) and Lith21 (Chr 10, 24 cM, LOD=2.9); one new, suggestive QTL (Chr 17) remains unnamed. Upon searching for epistatic interactions that contributed to gallstone susceptibility, the final suggestive QTL on Chr 7 was determined to interact significantly with Lith18 and, therefore, was named Lith22 (65 cM). A second interaction was identified between Lith19 and a locus on Chr 11; this QTL was named Lith23 (13 cM). mRNA expression analyses and amino acid haplotype analyses likely eliminated Slc10a2 as a candidate gene for Lith19. The QTLs identified herein largely contributed to gallstone formation rather than gallstone severity. Cloning the genes underlying these murine QTLs should facilitate prediction and cloning of the orthologous human genes. |
| Single and multiple cholesterol gallstones and the influence of bacteria Vitetta, L., S. P. Best, et al. (2000), Med Hypotheses 55(6): 502-6. Abstract: Single and multiple cholesterol gallstones constitute at least 80% of the gallstone population observed at cholecystectomy in Western countries. While supersaturation of bile with cholesterol is necessary for gallstone growth, the kinetic determinant of crystal nucleation is perhaps the critical factor leading to the incidence of gallstones. Nucleation involves aggregation of nidus-forming materials like pigment precipitates and mucus proteins. In combination with cholesterol precipitates and crystal formation, gallstone propagation is enhanced. Bacterial species may augment the process of nucleation and gallstone growth by contributing specific enzyme activities resulting in the formation of insoluble precipitates in bile, or by acting as a nidus upon which the deposition of cholesterol crystals may initiate gallstone formation. The utilization of Raman microscopic techniques permits detailed mapping of the distribution of the gallstone components leading to identification and characterization of the site of nucleation. This, when coupled to molecular genetic tools such as PCR DNA amplification, would permit elucidation of the role of bacteria in vivo gallstone propagation mechanisms. |