Effect of ethynylestradiol on biliary excretion of bile acids, phosphatidylcolines, and cholesterol in the bile fistula rat

The effects of ethynylestradiol on endogenous bile acids, their capacity to conjugate and excrete intravenously infused cholic acid, the concentrations of biliary cholesterol and lecithin, and the individual molecular species of phosphatidylcholine have been determined in male and female Sprague-Dawley rats. Endogenous biliary bile acids were analyzed by gas-liquid chromatography-mass spectrometry. Eleven bile acids were identified and several minor bile acids, primarily muricholates, could not be completely characterized. After 5 days of treatment with ethynylestradiol (1 mg/kg per day), the percentage of cholic acid decreased and the percentage of 6beta-hydroxylated bile acids, including several monounsaturated species, increased. Ethynylestradiol caused a decrease in bile acid-independent bile flow. Intravenous infusion of cholic acid at a high concentration caused cholestasis in control animals but, after ethynylestradiol treatment, cholestasis developed during the infusion of a much lower concentration of cholate, indicating a lowered threshhold for bile acid-induced cholestasis. In the treated rats, there was a slight increase in excretion of unconjugated endogenous bile acids, and a striking impairment of conjugation of intravenously administered cholic acid. One of the few sex-related differences observed was an increased concentration of biliary phospholipids in untreated male rats. Both phospholipid and cholesterol concentrations in the bile were higher in the treated animals. The molar percentage of cholesterol was always 1-2%, but it was slightly higher in treated animals, especially males. Ethynylestradiol treatment also affected biliary phospholipid by causing a marked increase of phosphatidylcholine species containing palmitic and oleic acid residues and a decrease of species containing stearic and linoleic acid residues. There was no increase in biliary excretion of long chain polyunsaturated species, which might have indicated damage to membranes, in response to ethynylestradiol either alone or with cholic acid infusion. Some of these ethynylestradiol-induced changes in biliary bile acid and lipid excretion are probably peculiar to the rat, but others, such as the increase in molar percentage of cholesterol and cholestasis, may be relevant to disorders in man, especially cholesterol gallstones and idiopathic cholestasis of pregnancy.     

Composition of biliary lipids and kinetics of bile acids after cholecystectomy in man

Postcholecystectomy biliary lipid composition and bile acid kinetics were studied in 24 women and 4 men. Hepatic bile was collected periodically for as long as 4 months without interrupting the enterohepatic circulation and without infecting the biliary system. In 23 patients with cholesterol gallstones, fasting biliary cholesterol made up 10.2% of total lipids in the steady state; in 5 patients with bilirubinate stones, saturation of fasting hepatic bile with cholesterol was lower (8.7% of total lipids). The percentage of deoxycholic acid after cholecystectomy was not higher than that of seven healthy, noncholecystectomized controls. Postcholecystectomy studies of diurnal variation of biliary lipids (7 patients) showed that postprandial hepatic bile had a significantly lower cholesterol saturation than fasting bile. Pool sizes of cholic and chenodeoxycholic acids were low (average 0.4 g/70 kg, each); total synthesis for both bile acids was normal (average 460 mg/day/70 kg), but fractional turnover rates of the two primary bile acids increased after cholecystectomy, probably due to more frequent recycling of the small bile acid pool.     

Differences in the erythrocyte aggregation level between veins and arteries of normolipidemic and hyperlipidemic individuals

The objectives of this study were to detect differences in the Doppler power backscattered by blood in vivo, and to identify factors affecting the backscattered power. The main hypothesis was that variations in the erythrocyte aggregation level between veins and arteries of normolipidemic and hyperlipidemic individuals can be detected with power Doppler ultrasound. Doppler measurements were performed at 5 MHz, with an Acuson 128 XP/10 system, over the carotid artery and jugular vein, external iliac artery and vein, common femoral artery and vein and popliteal artery and vein. Doppler signals were recorded at the center of each vessel to optimize the detection of erythrocyte aggregation, and processed off-line to obtain the backscattered power. The power of each recording was compensated for Doppler gain differences, tissue attenuation with depth and transmitted power variations occurring with pulse-repetition interval modifications. Results showed statistically stronger backscattered power in veins compared to arteries for the iliac, femoral and popliteal sites. In comparison with healthy subjects, stronger powers were observed in hyperlipidemic patients for the femoral and popliteal sites. Power differences were also found between peripheral measurements. On the other hand, no difference was observed between the power measured in the carotid artery and jugular vein for both groups of individuals. Multiple linear regression analyses were performed to identify factors affecting the backscattered power. Results showed a correlation (r) of 71.2% between the Doppler power in the femoral vein and the linear combination of two parameters: an erythrocyte aggregation index S10 measured with a laser scattering method, and the diameter of the vessel measured on B-mode images. Statistically significant linear correlation levels were also found between S10 and the Doppler power in various vessels. In conclusion, this study showed that power Doppler differences exist in vivo in large vessels between veins and arteries of normolipidemic and hyperlipidemic individuals. The Doppler power variations were also shown to be related to erythrocyte aggregation.     

Evaluation and clinical application of a direct low-density lipoprotein cholesterol assay in normolipidemic and hyperlipidemic adults

This study examines the performance and clinical use of a commercial immunoseparation assay for low-density lipoprotein (LDL) cholesterol in a sample population of normolipidemic and hyperlipidemic adult volunteers. Using paired fasting and nonfasting samples, we compared the direct LDL assay with the beta quantification method and the Friedewald calculation. Overall, the direct LDL assay correctly classified 82% and 60% of fasting and nonfasting subjects, respectively, into National Cholesterol Education Program risk groups. The Friedewald method correctly classified 84% of subjects. The fasting direct LDL assay has comparable positive and negative predictive values to the Friedewald method, except at an LDL cholesterol of 100 mg/dl. The nonfasting direct LDL assay demonstrates unacceptable positive predictive values when LDL cholesterol decreases to the 130 to 159 and > or = 160 mg/dl categories. Overall, direct LDL assay demonstrates limitations in the nonfasting state and at the LDL cholesterol level of 100 mg/dl used for patients with established coronary heart disease.     

Pancreatic bile salt-dependent lipase activity in serum of normolipidemic patients

Bile salt-dependent lipase (BSDL, E.C. 3.1.1.-) is a digestive enzyme secreted by the pancreatic acinar cell. Once in the duodenum, the enzyme, upon activation by primary bile salts, hydrolyzes dietary lipid esters such as cholesteryl esters and lipid-soluble vitamin esters. This enzyme is partially transferred from the duodenum or pancreas to the circulation where it has been postulated to exert a systemic action on atheroma-generating oxidized-low density lipoprotein (LDL). In the present study, sera from 40 healthy normolipidemic volunteers were used to investigate the possible linkage between circulating BSDL, lipids, and lipoproteins. We showed, firstly, that pancreatic-like BSDL activity can be detected in these serums. Secondly, BSDL activity increased significantly with the level of LDL-cholesterol and was also positively linked to the serum concentration of Apo B100 and Apo A-I. Thirdly, we also established that BSDL was associated with LDL, in part by a specific interaction with Apo B100, while no interaction was found with Apo A-I. No linkage with other recorded parameters (triglycerides, phospholipids, and high density lipoprotein-cholesterol) was detected. Because an increase in LDL-cholesterol represents an important risk factor for atheroma, the concomitant increase in BSDL, which can metabolize atherogenic LDL, suggests for the first time that this circulating enzyme may exert a positive effect against atherosclerosis.     

Relationship between biliary and serum bile acids and response to ursodeoxycholic acid in patients with primary biliary cirrhosis

OBJECTIVE: Ursodeoxycholic acid (UDCA) improves liver biochemistries and enriches the bile with UDCA in patients with primary biliary cirrhosis. The aim of this study was to determine whether the degree of enrichment of bile correlated with that of serum and whether either of these measures correlated with improvement in measures of liver disease. METHODS: In a randomized study, biliary and serum bile acid analyses were performed at entry and after 2 yr of UDCA or placebo. RESULTS: The percentage of ursodeoxycholic acid in bile increased by 42% in the UDCA group (n = 61) compared with 8% in the placebo group (n = 57) (p < 0.0001). Measurement of serum bile acids in 32 patients (18 ursodeoxycholic acid, 14 placebo) indicated that at 2 yr, ursodeoxycholic acid comprised 65% of serum bile acids in the treated group and 7% in the placebo group. Agreement between bile and serum was fair (r = 0.75, p < or = 0.00002) because in some patients, plasma but not biliary bile acids were enriched with UDCA. Changes in biliary ursodeoxycholic acid correlated significantly but weakly with the changes in serum alkaline phosphatase, AST, bilirubin, and in Mayo risk score. Correlations between changes in serum bile acid composition and biochemical measures of disease activity were even weaker. CONCLUSION: The measurement of biliary bile acids is superior to that of serum bile acids for assessing the compliance and changes in the circulating bile acids in patients receiving ursodeoxycholic acid for the treatment of primary biliary cirrhosis. Furthermore, measures to further increase the proportion of ursodeoxycholic acid in circulating bile acids should be explored.     

Lecithin supplementation in healthy volunteers: effect on cholesterol esterification and plasma, and bile lipids

Plasma and bile lipids and in vitro cholesterol esterifying activity of plasma (mg CE/dl/6 h) were determined in healthy volunteers who supplemented their regular diets with 7.5 g doses of soya lecithin three times daily for a 4-week period. Lecithin ingestion by the 4 male and 6 female subjects did not produce any significant changes either in total plasma cholesterol (TC) level or cholesterol esterification. A small but significant reduction was observed in the plasma triglyceride (TG) and total phospholipid (TPL) levels after supplementation. The molar percent of bile acids (BA), TC and TPL as well as the lithogenic index (LI = TC/BA + TPL) in both hepatic and gallbladder bile were also unaltered by 4 weeks of lecithin supplementation. In vitro cholesterol esterification was found linearly related to plasma-free cholesterol (r = 0.60, p less than 0.01) cholesterol ester (r = 0.50, p less than 0.05), total phospholipid (r = 0.50, p less than 0.05), lecithin (r = 0.45, p less than 0.05), and triglyceride (r = 0.57, p less than 0.025) levels.     

The relationship between serum lipids, apolipoproteins level and bile lipids level, chemical type of stone

To pick up serum high risk lithogenic factors predisposing one to gallstone formation and protective factors against gallstone formation in gallbladder. We compared serum lipid and apolipoprotein level of patients with gallbladder stone (stone group) with that of patients without gallbladder stone (control group). The correlation between serum lipid, apolipoprotein level and bile lipid level, cholesterol saturated index (CSI), characteristics of lipidemia in different kinds of gallbladder stones were studied. The results showed that the increase of serum Apo A1, C2 and E level in the stone group was more significant than in the control group. But there was no statistical significance in TC, TG, LDL-C, HDL-C, Apo A2, B, C3 level between the stone and control groups. These results suggested that serum apolipoproteins perhaps are more sensitive parameters than serum lipids in distinguishing patients with stones from those without stones. There were different profiles of serum lipid and apolipoproteins in different chemical types of gallbladder stones. Increased level in serum LDL-C, Apo B and ratio of LDL-C/HDL-C were characterized by an index for cholesterol stone, otherwise that in serum TG and Apo C2 an index for pigment stones. There was a positive correlation between serum total cholesterol (TC) or Apo B, C2, C3 and cholesterol amount or CSI in gallbladder bile. Therefore, TC, Apo B, C2, C3 could be considered as high risk lithogenic factors. A positive correlation existed between serum HDL-C and lecithin in gallbladder or common bile duct (CBD) bile as well as between HDL-C and bile acids in CBD bile. Thus, HDL-C might be a protective factor against gallstone formation in gallbladder.     

Influence of pectin structure on the interaction with bile acids under in vitro conditions

Structural parameters of pectin (a polysaccharide and important component of dietary fibre) influence the interaction with bile acids (BA). The effect of experimental conditions (concentration of pectin, BA and Ca2+) on such interactions was studied at pH 6.0. Series of pectins were used, prepared from virtually fully esterified pectin by gradual de-esterification with alkali or with pectinesterase from oranges. Further amidated and acetylated pectins were also tested. The greatest interaction with BA was found with a very highly esterified pectin under in vitro conditions. The interaction diminished with decreasing degrees of esterification (DE). This decrease was more intensive for pectins possessing a blockwise arrangement of free-COOH groups. Derivatives of pectin generally interacted less with BA. These results were principally confirmed with commercial pectins, with pectins prepared on a pilot-plant scale and with pectins originating from a defined botanical source. The interactions of these preparations with BA were less intensive than with those of pectins having an ideal random distribution of free -COOH groups in the polysaccharide molecules at the same DE. The interaction with pectin is also likely to be influenced by the structure of BA.     

Increased cholesterol content and esterification in rabbit aortic medial cells cultured in hyperlipidemic serum

Cells of early atherosclerotic lesions have an increased content of cholesteryl esters and enhanced rate of cholesterol esterification. The present study was carried out to elucidate whether these changes could be reproduced in a purely in vitro system. Cultures of rabbit aortic medial cells were incubated in a medium containing 10% of either normal rabbit serum (control cells) or serum from rabbits with cholesterol-induced hyperlipidemia (hyperlipidemic cells). The incorporation rate of [1-14C]oleate into cellular cholesteryl esters increased two- to threefold after four hours' incubation with hyperlipidemic serum and remained elevated during the rest of the eight days' study. After seven days' incubation the hyperlipidemic cells incorporated significantly more (+13%) oleate into triglycerides and significantly less (-15%) oleate into phospholipids than did the control cells. Cholesteryl ester content of the hyperlipidemic cells rose steeply for about two days, with a slower rise thereafter. In hyperlipidemic cells the esterified cholesterol content was significantly higher (315 ng/mug DNA) than in the control cells (79 ng/mug DNA). Hyperlipidemic cells showed a slow but significant rise of free cholesterol as well (from 1.15 mug/mug DNA in control to 1.50 mug/mug DNA). The results indicate that lipid changes resembling those in early atherosclerotic lesions can be brought about in vitro 0y treatment of aortic cells with hyperlipidemic serum.     

Comparative effects of atenolol versus celiprolol on serum lipids and blood pressure in hyperlipidemic and hypertensive subjects

Antihypertensive drugs may affect serum lipoprotein levels in mixed populations but data in hyperlipidemic patients are scanty. Atenolol versus celiprolol effects on serum lipoproteins were compared in 159 hyperlipoproteinemic hypertensive patients. This was a randomized, double-blind, parallel-group, positive-controlled multicenter trial with centralized lipoprotein laboratory and diet constancy monitoring. Blood pressure reduction and serum lipoprotein and apoprotein levels were monitored for 3 months. Both drugs reduced systolic and diastolic blood pressures. Atenolol had greater effects than celiprolol on diastolic pressure, but effects on systolic blood pressure were not different. Patients receiving atenolol had lower serum high-density lipoprotein cholesterol levels and higher low-density lipoprotein/high-density lipoprotein cholesterol ratios, whereas patients treated with celiprolol showed no contrasting changes. These differences in lipoprotein levels between drug treatment groups were statistically significant at weeks 9 and 12. The difference between drug treatments was also significant if the values of the 9- and 12-week visits were averaged. Patients taking atenolol had statistically significantly higher serum levels of total cholesterol, triglycerides and apoprotein B at 9 weeks. These divergent directional changes were consistent throughout and statistically significantly different between drugs.     

Direct spectrophotometry of total bile acids in serum

In this simple and direct method for determining total bile acids in serum, the serum was mixed with sodium pyruvate, a lactate dehydrogenase blocker, and bile acids were then measured spectrophotometrically after the following enzyme reaction. Bile acids are converted to 3-oxo bile acids with 3 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.50) with concomitant reduction of NAD+ to NADH. The hydrogen in the NADH generated is transferred by diaphorase (EC 1.6.4.3) to nitrotetrazolium blue to yield diformazan 540 nm). Analytical recovery of the various bile acids in serum averaged 96.2%. The CV for the day-to-day variation was 4.3%. Normal values are less than 7 mumol/L. Total serum bile acids were estimated by this method in 118 fasting patients with various liver diseases. This determination is clearly shown to be useful as a liver-function test.     

Serum 27-hydroxycholesterol in patients with primary biliary cirrhosis suggests alteration of cholesterol catabolism to bile acids via the acidic pathway

Reduced cholesterol synthesis has been reported in patients with primary biliary cirrhosis but no data are available on changes in cholesterol catabolism induced by the disease. Serum levels of 7alpha-hydroxycholesterol and 27-hydroxycholesterol have been measured in 25 patients (either normocholesterolemic or hypercholesterolemic) with primary biliary cirrhosis and in control subjects. To evaluate cholesterol synthesis, serum levels of lathosterol were measured, and campesterol and sitosterol were considered to reflect intestinal absorption and biliary elimination of sterols. In normocholesterolemic patients with primary biliary cirrhosis, lathosterol was significantly lower than in normocholesterolemic controls (P < 0.05) whereas no difference was found between hypercholesterolemic patients and hypercholesterolemic controls. Serum concentrations of sitosterol were significantly higher in both normocholesterolemic and hypercholesterolemic patients with primary biliary cirrhosis as compared with the respective controls (P < 0.01). In patients with primary biliary cirrhosis, serum 7alpha-hydroxycholesterol was slightly higher than in controls. 27-Hydroxycholesterol was significantly higher in hypercholesterolemic compared to normocholesterolemic controls (P < 0.05) and a significant linear correlation (r = 0.771; P < 0.001) was found between 27-hydroxycholesterol and cholesterol. In contrast, in patients with primary biliary cirrhosis, high cholesterol concentrations were not associated with increased serum levels of 27-hydroxycholesterol. Our data confirm that in patients with primary biliary cirrhosis, cholesterol synthesis and biliary elimination of sterols are impaired and also suggest that both the feedback regulation of retained bile acids on cholesterol 7alpha-hydroxylase and the scavenger effect on elevated serum cholesterol by cholesterol 27-hydroxylase are deficient in these patients. acids via the acidic pathway.     

Effect of heparin on lecithin: cholesterol acyltransferase and lipids in cholestasis

Injury to the hippocamp disturbs learning processes and short-term memory in 20-, 50- and 110-day rats. In 50-day rats, hippocampectomy results in lesser changes in learning and memory than in 20- and 110-day animals. Anatomo-physiological characteristics of the hippocamp in 20-day rats presumably indicate a particular importance of this structure at early stages of ontogenesis, when the brain cortex is not yet sufficiently mature and its connections with other structures are not completely formed. Non-linear dependence of learning disturbance in rats of varying age after hippocampectomy suggests that in rat hippocampal function undergoes changes during individual development of animals.     

Impaired absorption of cholesterol and bile acids in patients with an ileoanal anastomosis

BACKGROUND: No data exist on cholesterol absorption in patients with an ileoanal anastomosis (IAA). AIMS: To study cholesterol absorption and its effects on cholesterol and bile acid metabolism in patients with an IAA. PATIENTS AND METHODS: Cholesterol absorption, and serum, biliary, and faecal lipids were studied in 24 patients with an IAA and 20 controls. RESULTS: Fractional cholesterol absorption was significantly lower in the patients (36% versus 47% in controls). Surprisingly, the calculated intestinal influx of endogenous cholesterol was reduced so that the absolute absorption of cholesterol was decreased; elimination of cholesterol as faecal neutral steroids remained normal. Thus, the slightly increased cholesterol synthesis was mainly due to increased faecal bile acid excretion, which, in turn, was associated with reduced absorption and biliary secretion of bile acids. Serum total and low density lipoprotein (LDL) cholesterol and LDL triglycerides were lower in the patients. Molar percentage and saturation index of biliary cholesterol were slightly higher in patients with an IAA. Proportions of secondary bile acids in bile and faeces were diminished, and faecal unidentified bile acids were higher in patients. CONCLUSIONS: Cholesterol absorption is significantly impaired in patients with an IAA, and is closely related to changes in serum and biliary lipids observed in these patients.     

Dietary inulin lowers plasma cholesterol and triacylglycerol and alters biliary bile acid profile in hamsters

The mechanisms by which inulin may elicit its lipid-lowering effect are not well elucidated. To examine the lipid-lowering potential of inulin and especially its effect on bile acid metabolism, male golden Syrian hamsters were fed semipurified diets containing 20 g/100 g fat, 0.12 g/100 g cholesterol and 0 (control), 8, 12 or 16% inulin for 5 wk. Plasma total cholesterol concentrations were significantly lowered by 18, 15 and 29% in hamsters fed 8, 12 and 16% inulin, respectively. Dietary inulin specifically decreased VLDL cholesterol, which was significantly lower in hamsters fed 16% inulin compared with controls (1.1 +/- 0.3 vs. 2.9 +/- 0.6 mmol/L). LDL and HDL cholesterol were not significantly affected by dietary inulin. Plasma triacylglycerol was significantly reduced by 40 and 63% in hamsters fed 12 and 16% inulin, respectively. Hepatic total cholesterol and particularly esterified cholesterol accumulation were significantly lower in hamsters fed 8% inulin compared with controls. All three levels of dietary inulin caused distinct alterations in the bile acid profile of gallbladder bile. Taurochenodeoxycholic acid was significantly lower, whereas glycocholic and glycodeoxycholic acid were greater in hamsters fed inulin. Daily fecal bile acid excretion (micromol/d) tended to be greater (P = 0.056) in inulin-fed hamsters compared with controls, whereas daily neutral sterol excretion was not affected. These data demonstrate that the lipid-lowering action of inulin is possibly due to several mechanisms, including altered hepatic triacylglycerol synthesis and VLDL secretion and impaired reabsorption of circulating bile acids.     

A novel source of wheat fiber and protein: effects on fecal bulk and serum lipids

BACKGROUND: Polyethylene glycol (PEG) 3350 is a non-absorbable, non-metabolised osmotic agent used in lavage solutions for gut cleansing. AIMS: To compare the efficacy of PEG and lactulose in chronic constipation. METHODS: A total of 115 patients with chronic constipation entered a multicentre, randomised, comparative trial. They initially received two sachets containing either PEG (13 g/sachet) or lactulose (10 g/sachet) and were given an option to change the dose to one or three sachets/day, depending on response. RESULTS: Ninety nine patients completed the trial. After four weeks, patients in the PEG group (n=50) had a higher number of stools and a lower median daily score for straining at stool than patients in the lactulose group (n=49). Overall improvement was greater in the PEG group. Clinical tolerance was similar in the two groups, but flatus was less frequently reported in the PEG group. The mean number of liquid stools was higher in the PEG group but the difference was significant only for the first two weeks. There were no serious adverse events and no significant change in laboratory tests in either group. At the end of the study, the number of sachets used by the patients was 1.6 (0.7)/day in the PEG group and 2.1 (0.7)/day in the lactulose group. Sixty one patients completed a further two months open study of one to three sachets PEG daily; there was no loss of efficacy and no serious toxicity. Conclusion: Low dose PEG 3350 was more effective than lactulose and better tolerated.