Quantification of cholesterol nucleation promoting activity in human gallbladder bile

We have developed a simple method to quantitate cholesterol nucleation promoting activity in bile. The method makes use of the fact that gallbladder bile of cholesterol gallstone patients contains potent nucleation promoting activity. Gallbladder bile samples were serially diluted, routinely from 1/25 to 1/6,400. The diluted samples were mixed with a supersaturated model bile and the nucleation time (NT) of the mixtures was determined. The greatest dilution that resulted in a significant shortening of the NT was called the nucleation promoting activity titre (NPAT). The determination is independent of the original lipid content of the bile sample. The NPAT was measured in 14 gallbladder bile samples derived from patients with cholesterol gallstones and 9 controls. In all samples promoting activity was found. In the samples from the stone patients the NPAT was significantly elevated as compared to the patients without cholesterol stones (p = 0.01). Our results suggest that the cholesterol saturation index and the activity of cholesterol nucleation promoting factors are the most important factors in the pathogenesis of cholesterol gallstone disease. Assessment of the NPAT allows the differentiation of groups of patients with a normal cholesterol saturation index who are at risk for gallstone formation due to a high NPAT.     

Cholesterol kinetics in subjects with bile fistula. Positive relationship between size of the bile acid precursor pool and bile acid synthetic rate.

Our aim was to identify and quantitate cholesterol pools and transport pathways in blood and liver. By studying bile fistula subjects, using several types of isotopic preparations, simultaneous labeling of separate cholesterol pools and sampling all components of blood and bile at frequent intervals, we developed a comprehensive multicompartmental model for cholesterol within the rapidly miscible pool. Data in six components (bile acids, esterified cholesterol in whole plasma, and free cholesterol in blood cells, bile, alpha lipoproteins, and beta lipoproteins) were modeled simultaneously with the SAAM program. The analysis revealed extensive exchange of free cholesterol between HDL and liver, blood cells, and other tissues. There was net free cholesterol transport from HDL to the liver in most subjects. The major organ that removed esterified cholesterol from blood was the liver. A large portion (4,211 mumol) of total hepatic cholesterol comprised a pool that turned over rapidly (t1/2 of 72 min) by exchanging mainly with plasma HDL and was the major source of bile acids and biliary cholesterol. Only 6% of hepatic newly synthesized cholesterol was used directly for bile acid synthesis: the analysis showed that 94% of newly synthesized cholesterol was partitioned into the large hepatic pool (putative plasma membrane free cholesterol) which exchanged rapidly with plasma lipoproteins. Bile acid synthetic rate correlated directly with the size of the large hepatic pool. In conclusion, hepatic and blood cholesterol pools and transports have been quantitated. HDL plays a central role in free cholesterol exchange/transport between all tissues and plasma. In humans, the metabolically active pool comprises a large portion of total hepatic cholesterol that, in part, regulates bile acid synthesis.     

Reduced cystatin B activity correlates with enhanced cathepsin activity in progressive myoclonus epilepsy

BACKGROUND: Loss-of-function mutations in the gene encoding cystatin B (CSTB) underlie an inherited neurodegenerative disorder, progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1). CSTB is an inhibitor of several papain-family cysteine proteases, the lysosomal cathepsins. Its physiological function and the molecular pathways leading to the clinical EPM1 phenotype are unknown. AIM: To elucidate the role of CSTB and different cathepsins in pathogenesis of EPM1. METHOD: We determined the total papain inhibitory (cystatin) and papain-like (cathepsin) activity as well as specific activities of cathepsins B, H, L and S in lymphoblastoid cells of EPM1 patients, carriers and controls. RESULTS: In EPM1 patients, who express reduced levels of CSTB mRNA, the papain inhibitory activity was significantly decreased or absent. This reduction was correlated with significant increase in general cathepsin activity. The increase in cathepsin B, L and S activities was highly significant, whereas the increase in cathepsin H activity was not. CONCLUSIONS: This is the first demonstration of cysteine protease activity being regulated by CSTB activity in a biological context. The effects of decreased CSTB activity in EPM1 pathogenesis may, at least in part, be mediated by cathepsins through increased activity of cathepsins S and L.     

Reduced cystatin B activity correlates with enhanced cathepsin activity in progressive myoclonus epilepsy

BACKGROUND: Loss-of-function mutations in the gene encoding cystatin B (CSTB) underlie an inherited neurodegenerative disorder, progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1). CSTB is an inhibitor of several papain-family cysteine proteases, the lysosomal cathepsins. Its physiological function and the molecular pathways leading to the clinical EPM1 phenotype are unknown. AIM: To elucidate the role of CSTB and different cathepsins in pathogenesis of EPM1. METHOD: We determined the total papain inhibitory (cystatin) and papain-like (cathepsin) activity as well as specific activities of cathepsins B, H, L and S in lymphoblastoid cells of EPM1 patients, carriers and controls. RESULTS: In EPM1 patients, who express reduced levels of CSTB mRNA, the papain inhibitory activity was significantly decreased or absent. This reduction was correlated with significant increase in general cathepsin activity. The increase in cathepsin B, L and S activities was highly significant, whereas the increase in cathepsin H activity was not. CONCLUSIONS: This is the first demonstration of cysteine protease activity being regulated by CSTB activity in a biological context. The effects of decreased CSTB activity in EPM1 pathogenesis may, at least in part, be mediated by cathepsins through increased activity of cathepsins S and L.     

Endotoxin-induced mitochondrial damage correlates with impaired respiratory activity

OBJECTIVE: This study was designed to determine whether mitochondrial function in a systemic organ is acutely impaired in a resuscitated model of sepsis (endotoxemia, lipopolysaccharide) and the relationship, if any, between this impairment and the extent of mitochondrial ultrastructural damage that occurs. DESIGN: Perspective, controlled laboratory investigation. SETTING: Animal laboratory in a university research institute. SUBJECTS: Adult male cats. INTERVENTIONS: A well-established feline model of acute endotoxemia was used wherein measures were taken to minimize tissue hypoxia. After lipopolysaccharide (3 mg/kg intravenously, n = 9) or isotonic saline vehicle (control, n = 5) administration, liver samples were obtained at 4 hrs posttreatment, and mitochondrial ultrastructure and respiratory function were assessed. Mitochondrial ultrastructural injury was graded on a scale of 0 (no injury) to 5 (severe injury), and mitochondrial respiration was evaluated by using standard techniques. MEASUREMENTS AND MAIN RESULTS: Significant mitochondrial injury was apparent by 4 hrs, but only in the lipopolysaccharide-treated group (2.5 +/- 0.2 vs. 1.3 +/- 0.2, p <.001) and despite maintenance of tissue oxygen availability. In addition, lipopolysaccharide treatment reduced the rate of state 3 (adenosine 5'-diphosphate-dependent) respiration, especially at complex IV (40% inhibition), and increased the rate of state 4 (adenosine 5'-diphosphate-independent) respiration, reflecting partial uncoupling of mitochondrial oxidative phosphorylation. Finally, a significant correlation was demonstrated between the severity of ultrastructural injury and the magnitude of mitochondrial respiratory dysfunction after lipopolysaccharide treatment and despite resuscitation efforts. CONCLUSION: Mitochondrial function is significantly impaired during acute sepsis, and this impairment is strongly associated with the extent of mitochondrial ultrastructural abnormalities present in the tissues. These findings in conjunction with those previously shown suggest that mitochondrial functional impairment may contribute to the pathogenesis of altered oxygen metabolism in systemic organs during sepsis.     

Demographic correlates of physical activity in individuals with multiple sclerosis

Purpose. There is limited information about the demographic characteristics associated with participation in physical activity among those with multiple sclerosis (MS). Hence, the present study examined 12 demographic variables in association with physical activity in a sample of individuals with MS.

Method. Participants were 196 individuals with MS from the Midwestern portion of the United States. The participants provided demographic information and then wore a pedometer for a seven-day period.

Results. Analyses indicated that increasing age, use of a cane for ambulation, unemployment, and primary and secondary progressive MS were independently associated with less physical activity participation in this sample of MS patients.

Conclusion. Individuals with those characteristics are likely to be inactive and in need of a targeted intervention for increasing their participation in physical activity.     

Demographic correlates of physical activity in individuals with multiple sclerosis

PURPOSE: There is limited information about the demographic characteristics associated with participation in physical activity among those with multiple sclerosis (MS). Hence, the present study examined 12 demographic variables in association with physical activity in a sample of individuals with MS. METHOD: Participants were 196 individuals with MS from the Midwestern portion of the United States. The participants provided demographic information and then wore a pedometer for a seven-day period. RESULTS: Analyses indicated that increasing age, use of a cane for ambulation, unemployment, and primary and secondary progressive MS were independently associated with less physical activity participation in this sample of MS patients. CONCLUSION: Individuals with those characteristics are likely to be inactive and in need of a targeted intervention for increasing their participation in physical activity.     

Cholesterol saturation rather than phospholipid/bile salt ratio or protein content affects crystallization sequences in human gallbladder bile

BACKGROUND: In model biles, cholesterol crystallization (an important factor in gallstone formation) mainly depends on phospholipid/bile salt ratios with characteristic sequences of plate-like (monohydrate) vs. non-plate-like (presumed anhydrous: arcs, needles, tubules, spirals) cholesterol crystals. We now investigate whether the same phenomenon occurs in human bile. METHODS: Appearances of plate-like and non-plate-like cholesterol crystals were determined in filtered bile of 80 cholesterol gallstone patients, and related to biliary lipid and pro-nucleating protein composition. RESULTS: Non-plate-like crystals appeared before plate-like crystals in 9 biles, on the same day in 24 biles, and after plate-like crystals in 31 biles. In 16 biles only plate-like crystals were observed. Crystal sequences did not depend on biliary lipid or protein composition. Cholesterol saturation indexes were higher in biles with than without non-plate-like crystals (150 +/- 6 vs. 125 +/- 12, P = 0.02). In contrast, phospholipid/(bile salt + phospholipid) ratios, bile salt species, phospholipid classes, concentrations of mucin, IgG, IgM, IgA, haptoglobin and alpha-1 acid glycoprotein did not differ. CONCLUSIONS: Cholesterol crystallization sequences in human bile depend on cholesterol saturation index rather than on phospholipid/bile salt ratio.     

Biliary proteins. Unique inhibitors of cholesterol crystal nucleation in human gallbladder bile.

The onset time for cholesterol crystal nucleation of supersaturated normal human gallbladder biles is consistently prolonged when compared with biles from patients with cholesterol gallstone disease. Investigation of the factor(s) responsible for the suspended supersaturation (metastability) of normal human biles revealed that model bile solutions of cholesterol saturation index (CSI) and molar lipid composition identical to individual gallbladder bile specimens had much shorter crystal nucleation times, i.e., exhibited decreased metastability. Unsaturated normal biles, after supplementation with lecithin, cholesterol, and sodium taurocholate to a 'standard' supersaturated lipid composition, also demonstrated nucleation times three- to 15-fold longer than the comparable standard model bile. Total lipid extracts of normal biles, however, when similarly supplemented, did not differ in nucleation time from the control model solution. Gallbladder biles were fractionated by gel chromatography and the eluted fractions were pooled into two fractions. The fractions eluting in about the first 25% of the included volume when mixed with the supersaturated standard model bile induced a modest increase in nucleation time of approximately 1.5 times the control value. The fractions eluting in the second 25% of the included volume and which contained all of the bile lipids, were concentrated and supplemented with lipids to the standard composition. The nucleation times of these supplements were 3-10 times longer than the control nucleation times. Delipidated bile protein mixtures, purified by discontinuous sucrose gradient centrifugation, were recombined with purified lipids at the standard composition used previously. The nucleation times of these mixtures were significantly prolonged to the same extent as those associated with the second chromatographic fraction. These observations demonstrate that the delayed onset (inhibition) of cholesterol crystal nucleation observed in normal human gallbladder bile is produced by a factor(s) present in the biliary protein fraction.     

Cholesterol and bile acid balance in Macaca fascicularis. Effects of alfalfa saponins.

We determine the effects of alfalfa top saponins on cholesterol and bile acid balance in eight cynomolgus macaques (Macaca fascicularis). The monkeys ate semipurified food containing cholesterol with or without added saponins. The saponins decreased cholesterolemia without changing the levels of high density lipoprotein-cholesterol; hence, they reduced the total cholesterol/high density lipoprotein-cholesterol ratio. Furthermore, they decreased intestinal absorption of cholesterol, increased fecal excretion of endogenous and exogenous neutral steroids and bile acids, and decreased the percent distribution of fecal deoxycholic and lithocholic acids. The fecal excretion of fat was also slightly increased, but steatorrhea did not occur. We saw no signs of toxicity in the monkeys after 6 or 8 wk of saponin ingestion. The data suggest that alfalfa top saponins may be of use in the treatment of patients with hypercholesterolemia, but long-term studies on possible toxicity are needed before this therapy can be recommended for humans.     

Activity of cholesterol in human gallbladder bile in relation to nucleation of cholesterol monohydrate crystals.

To examine the hypothesis that the chemical activity of cholesterol molecules reflects the amount of cholesterol phasing out from bile associating with cholesterol monohydrate crystal nucleation, the cholesterol activities in human gallbladder biles from cholesterol gallstone patients, either untreated or treated with ursodeoxycholic acid, and from gallstone-free patients were determined in relation to the nucleation time and vesicular lipid composition. The cholesterol activity (nmol/disc/h) determined by the polyethylene disc uptake method was higher in the untreated gallstone group than the gallstone-free group (P less than 0.05) and the ursodeoxycholic acid treated group (P less than 0.01). The cholesterol activity correlated negatively with the nucleation time (P less than 0.01) and positively with both the vesicular cholesterol concentration (P less than 0.05) and the cholesterol/phospholipid ratio in vesicles (P less than 0.05). After the separation of vesicles from micelles by gel filtration, the cholesterol activity in the vesicular phase was found to be similar to that in the micellar phase. Interestingly, both the activities of cholesterol in the vesicular and micellar phases were significantly higher in the untreated gallstone group than in the gallstone-free group (P less than 0.05). These results suggest that cholesterol activity represents the amount of thermodynamically unstable cholesterol in bile.     

Effects of bile salt hydrophobicity on crystallization of cholesterol in model bile

Precipitation of cholesterol crystals is an essential step in gallstone formation. In the present study we found much faster and more extensive precipitation of various cholesterol crystal shapes in whole model biles containing the hydrophobic bile salt taurodeoxycholate than in biles containing the relatively hydrophilic taurocholate. Addition of taurodeoxycholate to isolated cholesterol–phospholipid vesicles also induced more crystallization than taurocholate. Crystallization behaviour in whole model biles and in vesicles after addition of corresponding bile salts was very similar. The very hydrophilic bile salts tauroursodeoxycholate and taurohyodeoxycholate never induced crystallization from vesicles, and crystallization in corresponding whole model biles did not occur. These bile salts also reduced crystallization dose dependently after addition of taurodeoxycholate to vesicles. Ultracentrifugation experiments suggested a higher vesicular cholesterol–phospholipid ratio for whole model biles containing more hydrophobic bile salts. These findings indicate that bile salt hydrophobicity influences shape of cholesterol crystals and extent of crystallization, possibly by modulating the vesicular cholesterol–phospholipid ratio.     

An easy procedure for determination of molar activity (or specific activity) of bile acids in bile

An easy procedure is described for determination of the molar activity of the major bile acids, labelled with 14C, in bile. The procedure involves initial enzymatic hydrolysis, by which the amino acid moieties are removed from the glycine and taurine conjugated bile acids by means of choloylglycine hydrolase, followed by thin-layer chromatographic separation of the unconjugated bile acids, cholic acid, chenodeoxycholic acid, and deoxycholic acid. Then the bile acids are eluted from the individual silica gel spots concerned. Finally, determination of the radioactivity by liquid scintillation counting and of the amount of substance by an enzymatic method using 3 alpha-hydroxysteroid dehydrogenase is performed in the eluates. The method requires only a small volume of sample and allows of separate determination of the molar activity of cholic acid and chenodeoxycholic acid, labelled with the same isotope, in the same sample.     

Social cognitive correlates of physical activity in inactive adults with multiple sclerosis

Persons with multiple sclerosis (MS) are often physically inactive. This observation has prompted the search for modifiable constructs derived from established theories that act as correlates of physical activity. This study investigated self efficacy, outcome expectations, impediments, and goal setting as correlates of physical activity in inactive persons with MS. Participants (n=54) completed a battery of measures as part of baseline data collection from an ongoing Internet intervention for increasing physical activity in inactive persons with MS. Bivariate correlation analysis indicated that physical activity was significantly correlated with outcome expectations (r=0.29), functional limitations (r=0.28), and goal setting (r=0.31), but not self efficacy (r=0.13). Multiple linear regression analysis indicated that only goal setting was significantly associated with physical activity (β=0.31). Such results suggest that goal setting may be a primary correlate of physical activity in inactive persons with MS.     

Peroxidase activity within circulating neutrophils correlates with pulmonary phenotype in cystic fibrosis

Excess neutrophils are present in the airways of patients with cystic fibrosis (CF). Myeloperoxidase (MPO) activity of acid extracts of sputum is directly correlated with airflow obstruction in CF patients. We hypothesized that the sputum MPO was derived from the MPO of neutrophils that entered the airways from the circulation. Active MPO without protease activity injures airways. If MPO activity from circulating neutrophils that emigrate into the airways of these patients causes increased airway epithelial permeability and mucus-gland secretion, then (1) those patients with greater MPO activity per circulating neutrophil would be more likely to produce sputum and (2) the MPO activity per circulating neutrophil would positively correlate with airflow obstruction. We determined the MPO activity for both circulating and sputum neutrophils. Spirometry and respiratory cultures were obtained simultaneously with blood and sputum samples. CF patients with more MPO activity within their circulating neutrophils were more likely to produce sputum ( P =.001, chi 2 test), and the MPO activity per circulating neutrophil was positively correlated with airflow obstruction as measured on the basis of the ratio of 1-second forced expiratory volume to forced vital capacity ( P <. 03, Kruskal-Wallace test). These associations were independent of age, sex, the results of respiratory-tract culture, or protease activity in the circulating neutrophils. MPO activity in circulating neutrophils from CF patients homozygotic for the deletion of phenylalanine at position 508 in the CF transmembrane regulator protein is directly related to the severity of these patients' pulmonary disease. Our results are consistent with the hypothesis that circulating neutrophils deliver active MPO to the airway, producing airway injury and airflow obstruction in homozygotic delF508 CF patients.     

Cholesterol esterase activity of human monocytes in ischemic heart disease

The comparison on the effect of atherosclerotic lesion of the vascular system on changes in the activity of human blood mononuclear cell lysosomal and cytoplasmic cholesterolesterases showed that these changes were of diverse nature an increase in lysosomal cholesterolesterase activity and a decrease in cytoplasmatic activity. It can be accounted for be a different role of acid and alkaline cholesteroesterases in cell cholesterol metabolism and by different mechanisms of the regulation of these enzymes.     

Brain microstructural correlates of visuospatial choice reaction time in children

The corticospinal tracts and the basal ganglia continue to develop during childhood and adolescence, and indices of their maturation can be obtained using diffusion-weighted imaging. Here we show that a simple measure of visuomotor function is correlated with diffusion parameters in the corticospinal tracts and neostriatum. In a cohort of 75 typically-developing children aged 7 to 13years, mean 5-choice reaction times (RTs) were assessed. We hypothesised that children with faster choice RTs would show lower mean diffusivity (MD) in the corticospinal tracts and neostriatum and higher fractional anisotropy (FA) in the corticospinal tracts, after controlling for age, gender, and handedness. Mean MD and/or FA were extracted from the right and left corticospinal tracts, putamen, and caudate nuclei. As predicted, faster 5-choice RTs were associated with lower MD in the corticospinal tracts, putamen, and caudate. MD effects on RT were bilateral in the corticospinal tracts and putamen, whilst right caudate MD was more strongly related to performance than was left caudate MD. Our results suggest a link between motor performance variability in children and diffusivity in the motor system, which may be related to: individual differences in the phase of fibre tract and neostriatal maturation in children of similar age, individual differences in motor experience during childhood (i.e., use-dependent plasticity), and/or more stable individual differences in the architecture of the motor system.     

Cholesterol gallstone pathogenesis: a study of potential nucleating agents for cholesterol crystal formation in bile

Cholesterol monohydrate crystal formation was measured quantitatively in model bile solutions, which were supersaturated with cholesterol, by a radiochemical method and qualitatively in human gallbladder bile by polarizing microscopy. Various agents, which have been postulated to act as nucleating factors for cholesterol crystal and gallstone formation, were added to bile and their effect on the appearance of cholesterol crystals was determined. These agents included calcium salts found in gallstones (calcite, aragonite, apatite, bilirubinate), Escherichia coli bacteria, pigment residues from cholesterol gallstones, bilirubin and several mucin preparations. Human gallbladder bile, which was collected from patients with and without cholesterol gallstones, was also mixed with model bile to examine whether nucleating or anti-nucleating factors were present. None of the agents tested markedly and consistently promoted cholesterol monohydrate crystal formation in model or human bile, except seed crystals of cholesterol monohydrate which were used as a control. Human gallbladder bile from obese patients without gallstones delayed the appearance of cholesterol crystals in model bile solutions, whereas gallbladder bile from gallstone patients did not. These results do not provide experimental support for the hypothesis that calcium salts and pigment material found in gallstones, or gallbladder mucin at concentrations less than 10 mg/ml, act as nucleating agents for cholesterol crystal and stone formation. The difference between gallbladder biles from patients with and without gallstones in their propensity to form cholesterol crystals may be due to the presence of an anti-nucleating factor in normal bile.     

脑梗死患者中的血清总胆固醇、低密度脂蛋白及非高密度脂蛋白胆固醇的含量分析

目的:探讨总胆固醇(TC)、低密度脂蛋白(LDL-C)及非高密度脂蛋白胆固醇(non-HDL-C)与脑梗死关系,为预防和临床治疗提供参考。方法:153例脑梗死患者分为单纯脑梗死组(57例)、合并糖尿病组(43例)、合并高血压组(53例),另设67例健康体检者为对照组,各组均测定血清三酰甘油(TG),TC和HDL-C,同时根据Friedewald公式计算出LDL-C,按Frost法计算出non-HDL-C含量,数据输入计算机进行分析。结果:脑梗死各组血清TC、LDL-C及non-HDL-C含量均高于对照组,有显著差异(P<0.01);脑梗死各组间比较,LDL-C无显著差异,但糖尿病组TC及non-HDL-C含量高于单纯脑梗死组和合并高血压组,有显著差异(P<0.01)。结论:TC及non-HDL-C与脑梗死的发生有关,应重视合并糖尿病的脑梗死患者血清non-HDL-C含量。