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High density lipoprotein cholesterol represents a major source of biliary cholesterol. Secretory phospholipase A2(sPLA2) is an acute phase enzyme mediating decreased plasma HDL cholesterol levels. Clinical studies reported a link between increased sPLA2expression and the presence of cholesterol gallstones. The aim of our study was to investigate whether the overexpression of human sPLA2in transgenic mice affects biliary cholesterol secretion and gallstone formation. Liver weight (P < 0.01) and hepatic cholesterol content (P < 0.01) were significantly increased in sPLA2transgenic mice compared with controls as a result of increased scavenger receptor class B type I (SR-BI)-mediated hepatic selective uptake of HDL cholesterol (P < 0.01), whereas hepatic SR-BI expression remained unchanged. However, biliary cholesterol secretion as well as fecal neutral sterol and fecal bile salt excretion remained unchanged in sPLA2transgenic mice. Furthermore, gallstone prevalence in response to a lithogenic diet was identical in both groups. These data demonstrate that i) increased flux of cholesterol from HDL into the liver via SR-BI as a result of phospholipase modification of the HDL particle translates neither into increased biliary and fecal sterol output nor into increased gallstone formation, and ii) increased sPLA2expression in patients with cholesterol gallstones might be a consequence rather than the underlying cause of the disease.

The phosphatidylethanolamine N-methyltransferase (PEMT) pathway of phosphatidylcholine (PC) biosynthesis is not essential for the highly specific acyl chain composition of biliary PC. We evaluated whether the PEMT pathway is quantitatively important for biliary PC secretion in mice under various experimental conditions. Biliary bile salt and PC secretion were determined in mice in which the gene encoding PEMT was inactivated (Pemt–/–) and in wild-type mice under basal conditions, during acute metabolic stress (intravenous infusion of the bile salt tauroursodeoxycholate), and during chronic metabolic stress (feeding a taurocholate-containing diet for 1 week). The activity of CTP:phosphocholine cytidylyltransferase, the rate-limiting enzyme of PC biosynthesis via the CDP-choline pathway, and the abundance of multi-drug-resistant protein 2 (Mdr2; encoded by the Abcb4 gene), the canalicular membrane flippase essential for biliary PC secretion, were determined. Under basal conditions, Pemt–/–and wild-type mice exhibited similar biliary secretion rates of bile salt and PC (∼145 and ∼28 nmol/min/100 g body weight, respectively). During acute or chronic bile salt administration, the biliary PC secretion rates increased similarly in Pemt–/–and control mice. Mdr2 mRNA and protein abundance did not differ between Pemt–/–and wild-type mice. The cytidylyltransferase activity in hepatic lysates was increased by 20% in Pemt–/–mice fed the basal (bile salt-free) diet (P < 0.05). We conclude that the biosynthesis of PC via the PEMT pathway is not quantitatively essential for biliary PC secretion under acute or chronic bile salt administration.

Early exposure to glucocorticoids (GC) has been proposed to disturb hepatic and cardiac function in later life. In the present study, we evaluated early metabolic alterations upon GC treatment that may predispose to long-term abnormalities. Rats were injected with dexamethasone (DEX) at d 1, 2, and 3 after birth and controls received saline (SAL). Rats were killed at 2, 7, and 14 d of age. Compared with SAL, DEX induced lower plasma insulin levels, hyperglycemia, hyperketonemia, and dyslipidemia at 2 d. At the same time, DEX treatment significantly increased expression of gluconeogenic and fatty acid oxidation genes in liver and expression of genes involved fatty acid utilization in heart. At 7 d, DEX-treated rats showed insulin resistance with hyperlipidemia, whereas hepatic and cardiac gene expression patterns were largely normalized. Hyperlipidemia and a significantly increased hepatic triglyceride content in DEX-treated rats were prominent at 14 d without large differences in hepatic and cardiac gene expression patterns. Thus, neonatal DEX administration transiently affects cardiac and hepatic gene expression patterns in suckling rats associated with sustained effects on plasma glucose and lipid concentrations. Whether these early effects of DEX contribute to hepatic and cardiac abnormalities at adult age needs further evaluation.

The oxysterol-activated nuclear receptor liver X receptor α (LXRα) has been implicated in the control of both cholesterol and fatty acid metabolism. In this study, we have evaluated the effects of excess dietary cholesterol on hepatic cholesterol metabolism, lipogenesis, and VLDL production in homozygous (Lxrα–/–), heterozygous (Lxrα+/–), and wild-type mice. Mice were fed either chow or a cholesterol-enriched diet (1%, w/w) for 2 weeks. On the high-cholesterol diet, fractional cholesterol absorption was higher in Lxrα–/–mice than in controls, leading to delivery of more dietary cholesterol to the liver. Lxrα–/–mice were not able to induce expression of hepatic Abcg5/Abcg8, and massive accumulation of free cholesterol and cholesteryl esters (CEs) occurred. Interestingly, despite the inability to upregulate Abcg5/Abcg8, the highly increased hepatic free cholesterol content did stimulate biliary cholesterol output in Lxrα–/–mice. Hepatic cholesterol accumulation was accompanied by decreased hepatic expression of lipogenic genes, probably caused by impaired sterol-regulatory element binding protein 1c processing, lower hepatic triglyceride (TG) contents, strongly reduced plasma TG concentrations (–90%), and reduced VLDL-TG production rates (–60%) in Lxrα–/–mice. VLDL particles were smaller and CE-enriched under these conditions. Lxrα deficiency did not affect VLDL formation under chow-fed conditions. Hepatic stearyl coenzyme A desaturase 1 expression was decreased dramatically in Lxrα–/–mice and did not respond to cholesterol feeding, but fatty acid profiles of liver and VLDL were only slightly different between Lxrα–/–and wild-type mice. Our data indicate that displacement of TGs by CEs during the VLDL assembly process underlies hypotriglyceridemia in cholesterol-fed Lxrα–/–mice.

Treatment with phototherapy or with the lipase inhibitor orlistat decreases plasma unconjugated bilirubin (UCB) concentrations in hyperbilirubinemic Gunn rats. We investigated the mechanism(s) underlying the effects of orlistat, phototherapy, and combined treatment, using steady-state 3H-UCB kinetics. After three weeks of treatment with orlistat (200 mg/kg chow), phototherapy (19 W/cm2/nm) or combined treatment, tracer 3H-UCB was administered IV to treated and untreated (control) Gunn rats. Plasma samples and feces were collected every 12h for 60h, and bile for 30 min at 60h. The following results were obtained: 1) each treatment decreased plasma bilirubin levels compared with controls: orlistat– 19%, phototherapy–32%, combined treatment–53%; 2) plasma bilirubin concentrations were strongly, negatively correlated with fractional bilirubin turnover; 3) orlistat treatment induced nettransmucosal excretion of UCB into the intestinal lumen, whereas phototherapy increased biliary UCB excretion rate; 4) all treatments profoundly increased the enterohepatic circulation of UCB derivatives, indicating enhanced metabolism by intestinal bacteria. In conclusion, orlistat and phototherapy lower plasma bilirubin concentrations in Gunn rats by increasing (net) intestinal influx of UCB, either by transmucosal excretion (orlistat), or increased biliary secretion (phototherapy). The mechanism of phototherapy and orlistat treatment involves increasing the availability of UCB in the intestinal lumen for fecal excretion and for metabolism by intestinal bacteria.

Peroxisome proliferator-activated receptors (PPARs) control the transcription of genes involved in lipid metabolism. Activation of PPARδ may have antiatherogenic effects through the increase of plasma HDL, theoretically promoting reverse cholesterol transport from peripheral tissues toward the liver for removal via bile and feces. Effects of PPARδ activation by GW610742 were evaluated in wild-type and Abca1-deficient (Abca1−/−) mice that lack HDL. Treatment with GW610742 resulted in an ∼50% increase of plasma HDL-cholesterol in wild-type mice, whereas plasma cholesterol levels remained extremely low in Abca1−/−mice. Yet, biliary cholesterol secretion rates were similar in untreated wild-type and Abca1−/−mice and unaltered upon treatment. Unexpectedly, PPARδ activation led to enhanced fecal neutral sterol loss in both groups without any changes in intestinal Abca1, Abcg5, Abcg8, and 3-hydroxy-3-methylglutaryl-coenzyme A reductaseexpression. Moreover, GW610742 treatment resulted in a 43% reduction of fractional cholesterol absorption in wild-type mice, coinciding with a significantly reduced expression of the cholesterol absorption protein Niemann-Pick C1-like 1 (Npc1l1) in the intestine. PPARδ activation is associated with increased plasma HDL and reduced intestinal cholesterol absorption efficiency that may be related to decreased intestinal Npc1l1expression.

Background & Aims: Reverse cholesterol transport (RCT) is defined as high-density lipoprotein (HDL)-mediated flux of excess cholesterol from peripheral cells to liver, followed by secretion into bile and disposal via the feces. Various steps of this pathway are controlled by the liver X receptor (LXR). We addressed the role of the intestine in LXR-dependent stimulation of fecal cholesterol excretion. Methods: To segregate biliary from intestine-derived cholesterol, wild-type and Mdr2 P-glycoprotein-deficient mice (Mdr2^-^/^-), which are unable to secrete cholesterol into bile, were treated with the LXR agonist GW3965. Results: Treatment with GW3965 increased biliary cholesterol secretion by 74% in wild-type mice but had no effect in Mdr2^-^/^- mice. LXR activation increased fecal neutral sterol excretion 2.1-fold in wild-type mice. Surprisingly, an identical increase was observed in Mdr2^-^/^- mice. Fractional cholesterol absorption was reduced on LXR activation in both strains but was more pronounced in Mdr2^-^/^- mice, coinciding with reduced Npc111 expression. Intestinal gene expression of ATP-binding cassette transporters (Abc) Abca1, Abcg1, Abcg5, and Abcg8 was strongly induced upon LXR activation in both strains, whereas expression of HMGCoA reductase, controlling cholesterol synthesis, remained unaffected. Additionally, LXR activation stimulated the excretion of plasma-derived [^3H]cholesterol into the fecal neutral sterol fraction in Mdr2^-^/^- mice. Conclusions: Increased fecal cholesterol loss upon LXR activation is independent of biliary cholesterol secretion in mice. An important part of excess cholesterol is excreted directly via the intestine, supporting the existence of an alternative, quantitatively important route for cholesterol disposal.

Peroxisome proliferator-activated receptor α (PPARα) is a nuclear receptor that controls expression of genes involved in lipid metabolism and is activated by fatty acids and hypolipidaemic fibrates. Fibrates induce the hepatic expression of murine multidrug resistance 2 (Mdr2), encoding the canalicular phospholipid translocator. The physiological role of PPARα in regulation of Mdr2 and other genes involved in bile formation is unknown. We found no differences in hepatic expression of the ATP binding cassette transporter genes Mdr2, Bsep (bile salt export pump), Mdr1a/1b, Abca1 and Abcg5/Abcg8 (implicated in cholesterol transport), the bile salt-uptake systems Ntcp (Na+-taurocholate co-transporting polypeptide gene) and Oatp1 (organic anion-transporting polypeptide 1 gene) or in bile formation between wild-type and Pparα(-/-) mice. Upon treatment of wild-type mice with ciprofibrate (0.05%, w/w, in diet for 2 weeks), the expression of Mdr2 (+3-fold), Mdr1a (+6-fold) and Mdr1b (+11-fold) mRNAs was clearly induced, while that of Oatp1 (-5-fold) was reduced. Mdr2 protein levels were increased, whereas Bsep, Ntcp and Oatp1 were drastically decreased. Exposure of cultured wild-type mouse hepatocytes to PPARα agonists specifically induced Mdr2 mRNA levels and did not affect expression of Mdr1a/1b. Altered transporter expression in fibrate-treated wild-type mice was associated with a 400% increase in bile flow: secretion of phospholipids and cholesterol was increased only during high-bile-salt infusions. No fibrate effects were observed in Pparα(-/-) mice. In conclusion, our results show that basal bile formation is not affected by PPARα deficiency in mice. The induction of Mdr2 mRNA and Mdr2 protein levels by fibrates is mediated by PPARα, while the induction of Mdr1a/1b in vivo probably reflects a secondary phenomenon related to chronic PPARα activation.

The ATP-binding cassette transporter ABCA1 is essential for high density lipoprotein (HDL) formation and considered rate-controlling for reverse cholesterol transport. Expression of the Abca1gene is under control of the liver X receptor (LXR). We have evaluated effects of LXR activation by the synthetic agonist T0901317 on hepatic and intestinal cholesterol metabolism in C57BL/6J and DBA/1 wild-type mice and in ABCA1-deficient DBA/1 mice. In wild-type mice, T0901317 increased expression of Abca1in liver and intestine, which was associated with a ∼60% rise in HDL. Biliary cholesterol excretion rose 2.7-fold upon treatment, and fecal neutral sterol output was increased by 150–300%. Plasma cholesterol levels also increased in treated Abca1−/−mice (+120%), but exclusively in very low density lipoprotein-sized fractions. Despite the absence of HDL, hepatobiliary cholesterol output was stimulated upon LXR activation inAbca1−/−mice, leading to a 250% increase in the biliary cholesterol/phospholipid ratio. Most importantly, fecal neutral sterol loss was induced to a similar extent (+300%) by the LXR agonist in DBA/1 wild-type and Abca1−/−mice. Expression of Abcg5and Abcg8, recently implicated in biliary excretion of cholesterol and its intestinal absorption, was induced in T0901317-treated mice. Thus, activation of LXR in mice leads to enhanced hepatobiliary cholesterol secretion and fecal neutral sterol loss independent of (ABCA1-mediated) elevation of HDL and the presence of ABCA1 in liver and intestine.

Background & Aims:Diabetes mellitus is associated with changes in bile formation. The aim of our study was to investigate the molecular basis for these changes in rats with experimentally induced diabetes. Methods:Expression of bile canalicular transporters was studied by reverse-transcription polymerase chain reaction, immunoblotting, and immunohistochemistry in control, streptozotocin-diabetic, and insulin-treated diabetic rats. Bile formation was studied under basal conditions and during stepwise increasing intravenous infusion of taurocholate to determine bile salt secretory rate maximum (SRm). Results:In diabetic rats, hepatic gene and protein expression of the multidrug resistance P-glycoprotein type 2 (Mdr2) were increased by 105% and 530%, respectively, associated with increased biliary phospholipid output (+520%) and phospholipid/bile salt ratio (+77%). Protein levels of the canalicular bile salt export pump (Bsep) were unchanged in diabetic rats, but basal biliary bile salt output and the SRm of taurocholate were increased by 260% and 130%, respectively, compared with controls. Alterations in transporter expression and bile formation were partly reversed by insulin administration. The bile salt SRm was strongly correlated with biliary phospholipid concentration (P< 0.001, R = 0.82). Conclusions:Induction of Mdr2expression and biliary phospholipid secretion, rather than Bsepexpression, appears to be responsible for the enhanced capacity of biliary bile salt secretion in experimentally induced diabetes.

The purpose of this study was to evaluate in a prospective, double-blind, placebo-controlled study the effect of long-term (2-year) lisinopril treatment on cardiovascular end-organ damage in patients with previously untreated isolated systolic hypertension (ISH). All patients with ISH were derived from a population screening program. End-organ damage measurements, done initially and after 6 and 24 months of treatment, included measurements of aortic distensibility and echocardiographic left ventricular mass index (LVMI) and diastolic function. Blood pressure was measured by office and ambulatory measurements. Of the 97 subjects with ISH selected from the screening, 62 (30 lisinopril) completed the study according to protocol. Office blood pressure decreased in both groups, but ambulatory results significantly decreased with lisinopril-treatment only. Aortic distensibility increased significantly with lisinopril, as opposed to a decrease in placebo-treated subjects. The main effect of increased distensibility occurred between 6 and 24 months, whereas ambulatory blood pressure changed mainly in the first 6 months of treatment. LVMI decreased in both treatment groups, with a significantly higher reduction in lisinopril-treated subjects. Left ventricular diastolic function showed no significant changes in either group. The vascular pathophysiologic alterations of ISH—a decreased aortic distensibility—can be improved with long-term lisinopril treatment, whereas values deteriorate further in placebo-treated subjects. These results, in one of the first studies including subjects with previously untreated ISH only, indicate that lisinopril treatment might favorably influence the cardiovascular risk of ISH.

To compare the effects of a calcium antagonist (amlodipine) and an angiotensin converting enzyme inhibitor (lisinopril) on left ventricular mass and diastolic function in elderly, previously untreated hypertensives.

In 1986, 242 M. E. Müller (MEM) cemented, straight-stem total hip arthroplasty prostheses were implanted in 229 patients; 15 hips (13 patients) were lost to follow-up. Of the remaining 227 implants, 180 were placed in women, and 47 were placed in men (each with mean age, 71 ± 7.7 years). After 10 years, 66 patients had died, and 152 implants were still in situ. As a result of aseptic loosening, 9 hips were revised (5 femoral and 4 acetabular components); two of these patients had a Girdlestone as a result of postoperative infection. Because 50% of the men died during follow-up, further analysis was performed with the 180 implants in women. The incidence of revision for aseptic loosening was 5.9 per 1,000 implants. The cumulative survival rate after 10 years was 94%. Survival was not influenced significantly by age, indication for operation, or having a contralateral hip prosthesis. The 10-year follow-up results for the MEM straight-stem total hip prosthesis in our hospital are satisfactory despite the probability that the cement mantle produced with this stem is not uniform in thickness.

Erythropoietic protoporphyria (EPP) is an inherited disorder of heme synthesis caused by deficiency of the mitochondrial enzyme ferrochelatase. EPP in humans is associated with liver disease, hypertriglyceridemia, and a low level of high density lipoprotein (HDL) cholesterol. To explore consequences of ferrochelatase deficiency in lipid metabolism, we have analyzed hepatic lipid content and plasma lipoprotein levels in chow-fed BALB/c mice homozygous ( fch/fch) or heterozygous ( fch/1) for a point mutation in the ferrochelatase gene and in wild-type controls (1/1). Livers of fch/fch mice show bile duct proliferation and biliary fibrosis, but bile formation is not impaired. The free cholesterol content of fch/fch livers is significantly increased when compared with fch/1 and 1/1 livers. Plasma cholesterol in fch/fch mice (9.9 +/- 6.4 mM) is elevated when compared with fch/1 and 1/1 mice (2.9 +/- 0.2 and 2.5 +/- 0.3 mM, respectively), because of an increased cholesterol content in the very low density lipoprotein-sized fractions, whereas HDL cholesterol is reduced. The ratio of cholesteryl ester to free cholesterol is 4.3 +/- 0.6, 3.3 +/- 0.3, and 0.3 +/- 0.1 in the plasma of 1/1, fch/1, and fch/fch mice, respectively. The latter is not due to reduced lecithin:cholesterol acyltransferase activity in plasma of fch/fch mice but to the presence of lipoprotein-X (Lp-X), a particle composed of bile-type lipids usually seen only in cholestatic conditions. Expression of mdr2, essential for biliary phospholipid/cholesterol secretion, is increased in fch/fch livers. In spite of this, biliary phospholipid/cholesterol secretion is reduced relative to that of bile salts. It is postulated that an inability of bile salts to stimulate lipid secretion adequately leads to formation of Lp-X in this noncholestatic condition. Distinct atherosclerotic lesions were found in aged fch/fch mice.Thus, ferrochelatase deficiency in mice leads to liver disease associated with altered hepatic lipid metabolism, a characteristic hyperlipidemia, and development of atherosclerosis.-Bloks, V. W., T. Plösch, H. van Goor, H. Roelofsen, J. Baller, R. Havinga, H. J. Verkade, A. van Tol, P. L. M. Jansen, and F. Kuipers. Hyperlipidemia and atherosclerosis associated with liver disease in ferrochelatase-deficient mice. J. Lipid Res. 2001. 42: 41;-50.

Background & Aims: It has been proposed that biliary phospholipids fulfill specific functions in the absorption of dietary fat from the intestine, but the physiological significance has not been established. The aim of this study was to evaluate the role of biliary phospholipids in dietary fat absorption in vivo by using mice homozygous or heterozygous for disruption of the Mdr2 gene (Mdr2^(^-^/^-^), Mdr2^(^+^/^-^)) and control (Mdr2^(^+^/^+^)) mice. Mdr2^(^-^/^-^) mice do not secrete phospholipids and cholesterol into bile, and bile salt secretion is not impaired. Mdr2^(^+^/^-^) mice show only impaired (-40%) phospholipid secretion. Methods: Methods included an analysis of time dependency of intestinal uptake and plasma appearance of intragastrically administered (radiolabeled) triglycerides and measurement of 3-day fecal fat balance with low- and high-fat diets. Results: Intragastric administration of olive oil resulted in a rapid increase in plasma triglycerides in Mdr2^(^+^/^+^) and Mdr2^(^+^/^-^) but not in Mdr2^(^-^/^-^) mice. The ''postprandial response'' of plasma triglycerides could be partially restored in Mdr2^(^-^/^-^) mice by intraduodenal infusion of whole rat bile. After intragastric [^3H]triolein administration in Triton WR1339-pretreated animals, the appearance of ^3H-triglycerides in plasma was reduced by 70% in Mdr2^(^-^/^-^) compared with Mdr2^(^+^/^+^) mice, excluding accelerated lipolysis as the cause of defective triglyceride response in Mdr2^(^-^/^-^) mice. ^3H-triglycerides accumulated in enterocytes in Mdr2^(^-^/^-^) mice. Surprisingly, the efficacy of fat absorption as derived from balance studies was not affected and was only minimally affected in Mdr2^(^-^/^-^) mice fed low (14 energy percent)- and high (35 energy percent)-fat diets, respectively (all >95%). Conclusions: The results show that biliary lipid secretion is necessary for postprandial appearance in plasma of chylomicrons in vivo but not for quantitative absorption of dietary lipids. GASTROENTEROLOGY 2000;118:173-182

Background/Aims:Fluorescent bile acids have proved useful for characterizing bile salt transport mechanisms. The aim of this study was to further validate the use of lysyl-fluorescein conjugated bile acid analogues as surrogate bile acids.

Objective: To determine, in a rat model of fat malabsorption, the potency of the carbon 13-labeled mixed triglyceride (^1^3C-MTG) breath test as a noninvasive, patient-friendly replacement for classic fat balance studies. Study design: Comparison of the percentage of fat absorption, detected by fat balance, with the ^1^3CO"2 recovery of the ^1^3C-MTG breath test in rats fed high-fat chow and varying amounts of the lipase inhibitor, orlistat (0, 50, 200, and 800 mg per kilogram of chow), for 5 days. Results: On orlistat administration, total fat absorption decreased from 80.2% +/- 2.2% to 32.8% +/- 3.7% (mean +/- SEM, 0 mg and 800 mg of orlistat per kilogram of chow, respectively; P < .001). Correspondingly, breath ^1^3CO"2 recovery from ^1^3C-MTG at 6 hours decreased from 84.5% +/- 7.8% to 42.0% +/- 1.5% of the dose (0 mg and 800 mg of orlistat per kilogram of chow, respectively; P < .001). The 6-hour recovery of breath ^1^3CO"2 appeared to be highly correlated with the percentage of fat absorption (r = 0.88, P < .001). In rats with fat absorption higher than 70%, however, the coefficient of variation of the ^1^3C-MTG breath test was 3-fold larger than that of the fat balance. Conclusions: The ^1^3C-MTG breath test could potentially replace the fat balance method for comparing fat absorption efficacy between groups. Yet, a considerable interindividual variation of the ^1^3C-MTG breath test under conditions of relatively mild fat malabsorption does not support its application for diagnostic purposes in individuals. (J Pediatr 1999;135:444-50)

Background & Aims: Reduced activity of ferrochelatase in erythropoietic protoporphyria (EPP) results in protoporphyrin (PP) accumulation in erythrocytes and liver. Liver disease may occur in patients with EPP, some of whom develop progressive liver failure that necessitates transplantation. We investigated the mechanisms underlying EPP-associated liver disease in a mouse model of EPP. Methods: Liver histology, indicators of lipid peroxidation, plasma parameters of liver function, and bile composition were studied in mice homozygous (fch/fch) for a point mutation in the ferrochelatase gene and in heterozygous (fch/+) and wild-type (+/+) mice. Results: Microscopic examination showed bile duct proliferation and biliary fibrosis with portoportal bridging in fch/fch mice. PP content was 130-fold increased, and thiobarbituric acid-reactive substances (+30%) and conjugated dienes (+75%) were slightly higher in fch/fch than in fch/+ and +/+ livers. Levels of hepatic thiols (-12%) and iron (-52%) were reduced in fch/fch livers. Liver enzymes and plasma bilirubin were markedly increased in the homozygotes. Plasma bile salt levels were 80 times higher in fch/fch than in fch/+ and +/+ mice, probably related to the absence of the Na^+-taurocholate cotransporting protein (Ntcp) in fch/fch liver. Paradoxically, bile flow was not impaired and biliary bile salt secretion was 4 times higher in fch/fch mice than in controls. Up-regulation of the intestinal Na^+-dependent bile salt transport system in fch/fch mice may enhance efficiency of bile salt reabsorption. The bile salt/lipid ratio and PP content of fch/fch bile were increased 2-fold and 85-fold, respectively, compared with +/+, whereas biliary glutathione was reduced by 90%. Similar effects on bile formation were caused by griseofulvin-induced inhibition of ferrochelatase activity in control mice. Conclusions: Bile formation is strongly affected in mice with impaired ferrochelatase activity. Rather than peroxidative processes, formation of cytotoxic bile with high concentrations of bile salts and PP may cause biliary fibrosis in fch/fch mice by damaging bile duct epithelium. GASTROENTEROLOGY 1999;117:696-705

The multidrug resistance protein MRP1 and its isoform MRP2 are involved in ATP-dependent glutathione S-conjugate transport and have similar substrate specificities. MRP2 mediates hepatic organic anion transport into bile. The physiological function of MRP1 in hepatocytes is unknown. Previous results show that MRP1 expression is low in quiescent hepatocytes but increased after SV40 large T antigen immortalization, suggesting a relationship with cell proliferation. Therefore, we determined mrp1 and mrp2 expression in rat hepatocytes in relation to the cell cycle. By varying cell density we obtained cultures that are mainly in G1 (high density) or have progressed into the S-phase or beyond (low density). In both cultures mrp1 mRNA and protein levels are increased, concomitantly with the disappearance of mrp2. This switch from mrp2 to mrp1 occurs in the G1 phase of the cell cycle and is associated with a decreased cell polarity. Mrp1 is located on lateral membranes or on intracellular vesicles, depending on whether cell-cell contact is established. In both locations mrp1 contributes to cellular glutathione S-conjugate efflux and protects against oxidative stress-inducing quinones. We conclude that a switch in expression from the apically located mrp2 to the basolaterally located mrp1 preserves glutathione S-conjugate transport in hepatocytes entering the cell cycle and protects against certain cytotoxic agents.

ApoE-deficient mice on low fat diet show hepatic triglyceride accumulation and a reduced very low density lipoprotein (VLDL) triglyceride production rate. To establish the role of apoE in the regulation of hepatic VLDL production, the human APOE3 gene was introduced into apoE-deficient mice by cross-breeding with APOE3 transgenics (APOE3/apoe-/- mice) or by adenoviral transduction. APOE3 was expressed in the liver and, to a lesser extent, in brain, spleen, and lung of transgenic APOE3/apoe-/- mice similar to endogenous apoe. Plasma cholesterol levels in APOE/apoe-/- mice (3.4 +/- 0.5 mM) were reduced when compared with apoe-/- mice (12.6 +/- 1.4 mM) but still elevated when compared with wild type control values (1.9 +/- 0.1 mM). Hepatic triglyceride accumulation in apoE-deficient mice was completely reversed by introduction of the APOE3 transgene. The in vivo hepatic VLDL-triglyceride production rate was reduced to 36% of control values in apoE-deficient mice but normalized in APOE3/apoe-/- mice. Hepatic secretion of apoB was not affected in either of the strains. Secretion of (3)H-labeled triglycerides synthesized from [(3)H]glycerol by cultured hepatocytes from apoE-deficient mice was four times lower than by APOE3/apoe-/- or control hepatocytes. The average size of secreted VLDL particles produced by cultured apoE-deficient hepatocytes was significantly reduced when compared with those of APOE3/apoe-/- and wild type mice. Hepatic expression of human APOE3 cDNA via adenovirus-mediated gene transfer in apoE-deficient mice resulted in a reduction of plasma cholesterol depending on plasma apoE3 levels. The in vivo VLDL-triglyceride production rate in these mice was increased up to 500% compared with LacZ-injected controls and correlated with the amount of apoE3 per particle. These findings indicate a regulatory role of apoE in hepatic VLDL-triglyceride secretion, independent from its role in lipoprotein clearance.

Bile secretion of trace elements, analyzed by proton-induced x-ray emission, was studied in rats with a congenital defect in hepatobiliary transport of organic anions Groningen Yellow (GY) rats, in which the process of bile secretion resembles that of the neonatal period. Bile flow(-41) and biliary glutathione secretion(-99) were drastically imparied in Gy rats compared with controls. Plasma concentrations of all detectable trace elements (Fe, Cu, Zn, Mo, Br, and Se), as well as that of simultaneously determined Ca, were similar in GY and age-matched control Wister rats. Bile concentrations of Fe, Mo, Br, and Ca were also similar in both groups, resulting in a ∼40 reduction of their secretion rates in GY rats. The concentrations of Zn(-62) and Mn (-64) were significantly lower in GY rats in contrast to that of Ca, which was 50 higher. Se could not be detected in bile of either group. Recovery in bile ( dose/3 h) after i.y. injection of MnCl2, CuSO4, or SeO2(1 mg metal/kg) was lower in GY rats than in controls: Mn, 26 and 35; Cu, 2.6 and 5; and Se, 1.5 and 5, respectively, injection of ZnSO4did not lead to increased Zn secretion in GY rats, and only 1.1 of the dose was recovered in controls. Thus, the hepatic handling of different endogenous and exogenously admjnistered trace metals is affected to a variable extent in the GY rat. For a number of metals (e.g.Fe, Mo), this may be related to the reduced bile flow: for others (e.g.Zn, Ma, Cu), other regulatory factors appear to be responsible. (Pediatr Res28: 339–343, 1990)

Background & Aims:mdr2P-glycoprotein (Pgp) deficiency in mice leads to the absence of biliary phospholipids and cholesterol in the presence of normal bile salt secretion. The aim of this study was to evaluate the importance of the biliary pathway in cholesterol homeostasis by determining the effects of mdr2Pgp deficiency on hepatic and plasma lipid levels and cholesterol kinetics in chow-fed mice. Methods:Hepatic lipid content, enzyme activities, plasma lipoprotein levels, and fecal sterol excretion were measured in wild-type (+/+) and mdr2Pgp–deficient (−/−) mice. Cholesterol kinetics were determined using radiotracer techniques. Results:No differences in hepatic lipid content were observed between (−/−) and (+/+) mice. Plasma high-density lipoprotein cholesterol and apolipoprotein A-I levels were strongly reduced in (−/−) mice compared with controls, whereas the apolipoprotein B contents of very-low-density lipoprotein and low-density lipoprotein were increased. Hepatic activity of 3-hydroxy-3-methylglutaryl–coenzyme A reductase was threefold greater in (−/−) mice than in controls; however, compartmental analysis of plasma cholesterol decay showed no differences in cholesterol synthesis between (−/−) and (+/+) mice. A dual isotope approach for estimating cholesterol absorption yielded ~50% lower values in (−/−) mice than in controls. Surprisingly, (−/−) mice showed a fourfold increase in fecal neutral sterol secretion. Conclusions:This study unequivocally establishes the important direct role of biliary lipids in the regulation of plasma lipid levels in mice.

We compared, in a prospective double-blind randomized study, the effect of the angiotensin-converting enzyme inhibitor quinapril (QUI) with that of triamterene/hydrochlorothiazide (THCT) treatment on cardiovascular end-organ damage in subjects with untreated isolated systolic hypertension (ISH). End-organ damage measurements, performed initially and after 6 and 26 weeks of treatment, included echocardiographic determination of left ventricular mass index (LVMI) and of diastolic function and measurement of aortic distensibility and peripheral vascular resistance. Blood pressure was significantly reduced in the 44 subjects (21 QUI, 23 THCT) completing the study. Both LVMI and aortic distensibility had changed at 6 weeks, with comparable improvements in both groups. LV diastolic function showed overall no significant changes, although patterns of early filling did differ between the two drug groups. Peripheral vascular resistance appeared to increase between 6 and 26 weeks in THCT subjects only, along with a decreased aortic distensibility. Blood pressure and LV mass were rapidly and markedly reduced in both treatment groups of ISH subjects, paralleled by an improvement of aortic distensibility. In interpreting these results, the pathophysiologic alterations in ISH need to be taken into account, because these differ strongly from those in diastolic hypertension. Results of LV diastolic function and peripheral vascular resistance were less clear but appear to show less favorable changes in the THCT subjects treatment group.

Low‐density lipoprotein receptors from adult human liver and the human hepatoblastoma cell line HepG2 were analyzed by polyacrylamide electrophoresis in SDS followed by immuno‐ and ligand botting. In both liver and HepG2 we detected a protein band with apparent relative molecular mass of 130 kDa, which is similar to that of the LDL receptor in fibroblasts. In addition we showed that HeLa cells also possess this LDL‐receptor protein.

We report an electroabsorption signal for the main IR-Vis absorption peak in thin films of polysquaraine. Spectra from 1.0 to 2.0 eV at a temperature of 10 K show a positive peak at 1.29 eV, followed by a negative peak at 1.35 eV with vibronic structure on the high energy wing. The results are discussed in terms of a Stark effect on molecular states. Using the results a Stark shift of about 1 meV is calculated, consistent with values for other π-conjugated polymer systems.

Can two isolated radical cations (polarons) exist simultaneouslyon a π‐conjugated chain or do they coalesce into a single, doubly charged spinless (bipolaron) deformation? This long‐standing question, fundamental to charge transport in conducting polymers, is now resolved by an investigation of the redox states of long oligothiophenes (below) in solution. In contrast to short oligothiophenes, for long oligothiophene dications two individual polarons prevail because of the decrease in Coulomb repulsion energy obtained by moving the two charges apart.

Recently we demonstrated that dietary fish oil (FO) causes changes in intrahepatic cholesterol transport and hypersecretion of cholesterol into bile in rats (J. Clin. Invest. 88: 943-951, 1991). We have now investigated in more detail the relationship between cholesterol and bile acid secretion in rats with chronic bile diversion fed purified diets supplemented (9% wt/wt) with either FO or corn oil (CO) for 2 weeks. Effects of FO on biliary cholesterol secretion (+ 400%; as compared to CO after 14 days) were much more pronounced than previously observed in rats with intact enterohepatic circulation (+50%). Biliary bile acid (+30%) and phospholipid (+120%) secretion were increased to a much lesser extent than that of cholesterol resulting in the formation of bile supersaturated with cholesterol. The biliary cholesterol/bile acid molar ratio was 0.069 and 0.032 in FO- and CO-fed rats, respectively, at noon of day 14. This ratio increased to 0.108 in FO-fed rats at midnight, when bile acid output was maximal, but remained unchanged in CO-fed rats during the day-night cycle. Intravenous administration of taurochenodeoxycholic acid (15 mumol/kg) resulted in a 2-fold increase in bile acid output and a simultaneous 1.6-fold stimulation of cholesterol secretion in both groups, implying that administration of the bile acid induced the secretion of 2-3 times as much cholesterol in FO- than in CO-fed rats. Likewise, administration of bilirubin ditaurate (30 mumol/kg), an inhibitor of bile acid-induced biliary lipid secretion, reduced cholesterol output in both groups by about 50% while bile acid output remained unchanged. It is concluded that, in rats, dietary fish oil increases the disposition of cholesterol into bile by potentiating bile acid-dependent cholesterol secretion, presumably by facilitating the recruitment of bile-destined cholesterol.

1. Sulphated glycolithocholic acid (SGLC) causes cholestasis in experimental animals, despite its sulphated form. In the present study, the cholestatic potency and the pharmacokinetics of SGLC were investigated in rats under two conditions: (a) in the presence of an intact circulating bile acid pool and (b) after exhaustion of the bile acid pool by 24 h of bile diversion. 2. Intravenous administration of SGLC (8 μmol/ 100 g body weight) to rats with an intact bile acid pool did not cause cholestasis. However, biliary phospholipid and cholesterol concentrations were reduced by 40% and 29% respectively during the first hour after administration. When the same dose of the bile acid was injected in rats with a 24 h biliary drainage, a complete cessation of bile production was observed within 1 h. Twelve hours after the onset of cholestasis, bile production gradually increased again, showed a marked overshoot, and reached control levels after 3 days. In the recovery phase, biliary phospholipid and cholesterol concentrations were greatly reduced. 3. The absence of endogenous bile acids did not change the hepatic clearance rate of a tracer dose of radiolabelled SGLC, but markedly decreased its biliary excretion rate. 4. It was concluded that the hepatotoxic effect of SGLC is much more pronounced in rats with an exhausted bile acid pool, possibly due to a slower biliary excretion of the toxic compound. This phenomenon may have clinical implications for patients with a contracted bile acid pool.

The present study concerns short- and long-term effects of interruption of the enterohepatic circulation (EHC) on hepatic cholesterol metabolism and biliary secretion in rats. For this purpose, we employed a technique that allows reversible interruption of the EHC, during normal feeding conditions, and excludes effects of anaesthesia and surgical trauma. [3H]Cholesteryl oleate-labelled human low-density lipoprotein (LDL) was injected intravenously in rats with (1) chronically (8 days) interrupted EHC, (2) interrupted EHC at the time of LDL injection and (3) intact EHC. During the first 3 h after interruption of the EHC, bile flow decreased to 50% and biliary bile acid, phospholipid and cholesterol secretion to 5%, 11% and 19% of their initial values respectively. After 8 days of bile diversion, biliary cholesterol output and bile flow were at that same level, but bile acid output was increased 2-3-fold and phospholipid output was about 2 times lower. The total amount of cholesterol in the liver decreased after interruption of the EHC, which was mainly due to a decrease in the amount of cholesteryl ester. Plasma disappearance of LDL was not affected by interruption of the EHC. Biliary secretion of LDL-derived radioactivity occurred 2-4 times faster in chronically interrupted rats as compared with the excretion immediately after interruption of the EHC. Radioactivity was mainly in the form of bile acids under both conditions. This study demonstrates the very rapid changes that occur in cholesterol metabolism and biliary lipid composition after interruption of the EHC. These changes must be taken into account in studies concerning hepatic metabolism of lipoprotein cholesterol and subsequent secretion into bile.

The ground state dipole moment. [image omitted], and the change in dipole moment upon excitation, [image omitted], of various dyes have been determined from electrochromic measurements on solutions in polymer matrices. The merits of this method are discussed. High values of [image omitted], much in excess of the sum of local group moments, are found for compounds in which a polar ground state is stabilized by large differences in electronegativity of the constituting groups ("Zwitterions") and/or by a gain in resonance energy accompanying a charge transfer in π-electron ring systems. High values of [image omitted], indicating a large charge transfer upon excitation, are connected with a loss of resonance energy. The amount of charge, transferred upon excitation from the donor group of the dye to the acceptor group, does not decrease significantly if the geometric distance between these groups is increased by inserting enthynylenic groups.

The synthesis and (chir)optical properties of a highly regioregular optically active 3-substituted polythiophene are reported. Using the McCullough method a regioselectivity of more than 98% is found for the head-to-tail coupling in 3-[2-((S)-2-methylbutoxy)ethyl]polythiophene 1. Contrary to the small effects observed for the regiorandom analogue 2, made by FeCl3-polymerization, 1 shows a strong induced optical activity in its π-π* transition, provided the polymer is in its almost coplanar associated form. This association with a strong conformational rigidity, a prerequisite for a stable chirality from a helical structure of 1, is found in poor-solvents as well as in the solid state. In a good solvent like CHCl3, the disordered non-planar structure is optically inactive in its backbone. The transfer to an associated form is accompanied with solvatochromism and thermochromism in absorption, while significant changes in fluorescence behaviour and in the circular dichroism spectra are observed. All techniques show fine structure in the almost coplanar state while all absorptions are exciton coupled, reflecting the Davydov splitting of the coupled excited states.

Absorption and emission spectra of the title oligothiophenes, both in chloroform solution and as solid (or in PMMA ss), are given. Evidence is found for the simultaneous existence of various conformers that differ markedly in their conjugation lengths.

Nucleophilic photosubstitution reactions of some naphthalene derivatives have been studied in order to establish new data on rate constants and other quantitative aspects of nucleophilic aromatic photosubstitution reactions. Results show that the photoreactions of the metasubstituted fluoronitro‐ and methoxynitronaphthalenes with hydroxide ion and methylamine are SN2(3Ar*) processes. In addition, it is shown that the lifetimes of the excited species in aromatic photosubstitution may be a decisive factor in determining the nature and the quantum yield of the reaction at moderate and low nucleophile concentration.

Effects of 17alpha-ethinylestradiol (EE) on the neutral and acidic biosynthetic pathways of bile salt (BS) synthesis were evaluated in rats with an intact enterohepatic circulation and in rats with long-term bile diversion to induce BS synthesis. For this purpose, bile salt pool composition, synthesis of individual BS in vivo, hepatic activities, and expression levels of cholesterol 7alpha-hydroxylase (CYP7A), and sterol 27-hydroxylase (CYP27), as well as of other enzymes involved in BS synthesis, were analyzed in rats treated with EE (5 mg/kg, 3 days) or its vehicle. BS pool size was decreased by 27% but total BS synthesis was not affected by EE in intact rats. Synthesis of cholate was reduced by 68% in EE-treated rats, while that of chenodeoxycholate was increased by 60%. The recently identified Delta22-isomer of beta-muricholate contributed for 5.4% and 18.3 % (P < 0.01) to the pool in control and EE-treated rats, respectively, but could not be detected in bile after exhaustion of the pool. A clear reduction of BS synthesis was found in bile-diverted rats treated with EE, yet biliary BS composition was only minimally affected. Activity of CYP7A was decreased by EE in both intact and bile-diverted rats, whereas the activity of the CYP27 was not affected. Hepatic mRNA levels of CYP7A were significantly reduced by EE in bile-diverted rats only; CYP27 mRNA levels were not affected by EE. In addition, mRNA levels of sterol 12alpha-hydroxylase and lithocholate 6beta-hydroxylase were increased by bile diversion and suppressed by EE.This study shows that 17alpha-ethinylestradiol (EE)-induced intrahepatic cholestasis in rats is associated with selective inhibition of the neutral pathway of bile salt (BS) synthesis. Simultaneous impairment of other enzymes in the BS biosynthetic pathways may contribute to overall effects of EE on BS synthesis.

The Pd-catalyzed cross-coupling reaction involving organostannanes (Stille reaction) is applied to prepare a series of N-t-BOC-protected D−π−A oligopyrroles. After purification, oligomers with one to four pyrrole units inserted between a 4-nitrophenyl and a 4-methoxyphenyl group are isolated in yields between 20 and 47%. Only minor differences in the linear optical properties are observed for the four oligomers. The charge-transfer band around λmax = 365 nm shows a small, unexpected, hypsochromic shift, while the π−π* band around λmax = 285 nm shows a small, expected, bathochromic shift upon elongation of the molecule. Their nonlinear optical properties, however, show a surprising proceeding; going from the D−π−A oligomer with one pyrrole unit to that with three pyrrole units, the hyperpolarizability, as measured by hyper-Rayleigh scattering, increases additionally with the number of pyrrole units within the oligomer, up to 277 × 10^-30 esu in case of the trimer. On the basis of the assumption that both transitions contribute to the hyperpolarizability, a better conjugated D−π−A oligomer with a bithienyl spacer inserted between a 2-(4-nitrophenyl)-5-pyrrolyl and a 2-(4-methoxyphenyl)-5-pyrrolyl group is prepared analogously. This molecule shows only one combined absorption at λmax = 378 nm for both the charge transfer and the π−π* band, while the hyperpolarizability is as high as 440 × 10^-30 esu. These data, showing a very favorable transparency−hyperpolarizability tradeoff, are explained in terms of the contribution of two transitions that are superimposed.

In an attempt to improve on the properties of PEDOT (poly(3,4-ethylenedioxythiophene)) as a stable, conducting, and transparent coating we synthesized four different alkoxy-substituted poly(thienylene−vinylene)s, 1−4, using the Stille coupling reaction. The oligomers and polymers obtained were characterized and their NIR−vis absorption spectra were measured as a function of doping, both electrochemically as films and chemically in solution. Similar spectra of PEDOT films were gathered for comparison. In PEDOT a change in doping level does not change the energies of the absorption bands, while for the other polymers the bands shift markedly and the NIR peak at high doping level lies at a higher energy. The polymers 1−4 are much less suited for the intended coatings than PEDOT. Possible reasons for this are discussed.

Several compounds, in particular bile acids, undergo enterohepatic circulation (EHC). Limited data are available on the pathophysiologic aspects of this circulation. In the present study we describe a surgical technique in rats that allows a long-term, reversible interruption of the EHC and monitoring of peripheral blood levels without direct surgical intervention. This technique excludes the effects of anesthesia and surgical trauma. The model's validity has been tested extensively. We used this animal model to investigate acute and chronic effects of interruption and subsequent restoration of the EHC on (a) nutritional status, (b) plasma cholesterol levels and hepatic cholesterol synthesis, and (c) biliary bile acid, phospholipid, and cholesterol excretion. Interruption of the EHC resulted in an increased food intake and enhanced fecal energy loss, caused by a less efficient intestinal absorption. Plasma cholesterol concentrations declined immediately after the interruption of the EHC, but returned to almost control values during bile diversion. A marked overshoot followed the subsequent restoration of the EHC. Hepatic cholesterol synthesis showed a fivefold increase after 8 days of bile diversion but returned to control values within 2 days after restoration of the EHC. After interruption of the EHC, bile acid, phospholipid, and cholesterol excretion decreased sharply but stabilized after 3 h at 7.6%, 20%, and 23%, respectively, of their initial values. Bile acid output, representing hepatic synthesis, slowly increased over 4 days, but never exceeded 13% of its value during intact EHC. Subsequent restoration of the EHC could rapidly reverse the observed effects of the interruption. The animal model described in the present study is an excellent tool in studying the acute and chronic effects of disturbances of the EHC.

Altered bile acid metabolism has been claimed to play a role in the etiology of benign recurrent intrahepatic cholestasis (BRIC). Therefore, we studied bile acid metabolism in detail in 10 patients with this syndrome. Pool sizes of both primary bile acids were estimated simultaneously, using deuterated cholic acid and chenodeoxycholic acid. The pool sizes of cholic acid and chenodeoxycholic acid, expressed in micromoles per kilogram body weight, were significantly contracted in BRIC patients during a cholestasis-free period: 8.0 ± 4.2 and 11.7 ± 4.7, respectively, versus 24.1 ± 11.7 and 22.9 ± 7.8 in controls. Fractional turnover rates (per day) for cholic acid and chenodeoxycholic acid were increased: 0.70 ± 0.29 and 0.58 ± 0.27, respectively, versus 0.29 ± 0.12 and 0.23 ± 0.10 in controls. Bile acid pool composition expressed as percentages in BRIC patients was cholic acid 34 ± 17, chenodeoxycholic acid 38 ± 9, deoxycholic acid 27 ± 18, and lithocholic acid 1 ± 1, with a glycine to taurine conjugation ratio of 6.7 ± 4.9. Corresponding values for 32 controls were cholic acid 57 ± 13, chenodeoxycholic acid 29 ± 9, deoxycholic acid 14 ± 9, and lithocholic acid <1, with a glycine to taurine conjugation ratio of 2.4 ± 1.3. Fecal bile acid loss, in micromoles per kilogram body weight per day, was 11.2 ± 9.0 in BRIC patients compared with 2.8 ± 1.4 in controls. The serum 7α-hydroxycholesterol level (nanomoles per liter) was significantly increased in BRIC patients: 326 ± 179 versus 171 ± 90 in controls. These results suggest that in BRIC patients spillover of bile acids into the colon occurs, which leads to increased fecal bile acid loss and a reduced bile acid pool size. Increased serum 7α-hydroxycholesterol is probably indicative of an accelerated bile acid synthesis rate due to increased activity of cholesterol 7α-hydroxylase, the enzyme catalyzing the first step in the major pathway of bile acid synthesis. The results of our study suggest that in BRIC patients a contracted bile acid pool increases the susceptibility of the liver for cholestatic agents.

A number of organic anions has been shown to inhibit biliary phospholipid and cholesterol secretion without affecting bile acid secretion. However, the mechanism of this uncoupling phenomenon is still unclear. This study shows a comparison of the effects of ampicillin (18 μmol/100g body wt), sulfated taurolithocholic acid (0.2 and 1.0 μmol/100 g body wt), and indocyanine green (0.6 μmol/100g body wt) in control and Groningen Yellow-Wistar rats with chronic (8 days) biliary drainage. Groningen Yellow rats have a hereditary defect in hepatobiliary transport of various organic anions. Bile secretion, but not hepatic uptake, of the three organic anions was strongly impaired in Groningen Yellow rats compared with controls. Ampicillin and sulfated taurolithocholic acid caused a strong uncoupling in control rats but had no effect or a much smaller effect on lipid secretion in Groningen Yellow rats. Indocyanine green did not affect lipid secretion, in either control or in Groningen Yellow rats. Gel-filtration chromatography of bile showed a specific coelution of ampicillin and sulfated taurolithocholic acid with the bile acid fraction, whereas indocyanine green coeluted with the phospholipid/cholesterol fraction. This study concludes that the uncoupling by ampicillin and sulfated taurolithocholic acid occurs after their secretion into bile and is caused by interaction of these compounds with bile acids. It is hypothesized that this interaction inhibits the capacity of bile acids to induce secretion of phospholipids and cholesterol into the bile.

The development of cytosolic DT-diaphorase – NAD(P)H dehydrogenase, quinone, EC 1.6.99.2 – and its induction by benzo(a)pyrene has been studied in rat liver. DT-diaphorase belongs to the late suckling cluster, because the largest increase in activity can be observed 18 days after birth. A considerable activity is present, however, in the neonatal period. The activity of the enzyme can be prematurely induced by benzo(a)pyrene. A lag phase of 10 h can be observed before the activity of DT-diaphorase starts to increase. This increase in activity proved to be sensitive to inhibitors of mixed-function oxydase and RNA and DNA synthesis.

In this study the effects of bile acids and other organic anions on the secretion of very-low-density lipoproteins (VLDLs) were evaluated in rat hepatocytes in primary culture. Incubation of cells with portal blood concentrations (10–200 μM) of bile acids resulted in dose-dependent suppression of secretion of VLDL-associated [3H]triglyceride (TG) formed from [3H]glycerol, and also of TG mass. The degree of the inhibition was highly correlated with intracellular bile acid concentration. Prolonged incubation with 100 μM extracellular taurocholic acid (TC) decreased the secretion of [3H]TG and TG mass to 35% and 50% of the controls respectively. Cellular content of mass and of [3H]TG during prolonged incubation with TC were about 20% and 60% higher than the controls respectively. The inhibitory effect remained for at least 24 h in the presence of TC without altering VLDL-lipid and VLDL-apolipoprotein compositions or the size distribution of the particles. Secretion of apoB-100 and of apoB-48 was inhibited to a similar extent. Cells largely lost their capacity to accumulate bile acids intracellularly after 48 h in culture. In these cells TC was unable to exert its suppressive effects. Taurine and glycine conjugates of all common bile acids were capable of suppressing [3H]TG secretion. Trihydroxylated (cholic acid) and various dihydroxylated (deoxycholic, chenodeoxycholic and ursodeoxycholic acids) bile acids had similar capacities in this respect, suggesting that their common sterol-3α-OH structure is required for the suppressive effect. Neither non-bile acid organic anions, e.g. bilirubin ditaurate and dibromosulphthalein, nor dianionic bile acid metabolites, e.g. sulphated taurolithocholic acid and lithocholate-3-O-glucuronide, showed any effect on [3H]TG secretion. These results indicate that bile acids might play a physiological role in regulating VLDL production by the liver, especially in the postprandial state when their enterohepatic circulation is stimulated.

A randomized double-blind study lasting 2 months was performed with either 25 mg captopril twice a day or 50 mg atenolol once a day in 125 patients with established diastolic hypertension (diastolic blood pressure>95 mmHg) identified during a population screening programme of subjects aged<65 years. Quality of life was assessed from self-completed questionnaires. A significant fall in diastolic blood pressure occurred with both captopril (106.7 ± 7.0 to 98.6 ± 8.6 mmHg) and atenolol (107.4 dh 7.5 to 98.2 ± 8.1 mmHg) but there was no difference between the two drugs in the size of the fall. A measure of the number of symptomatic complaints, the symptom complaint rate, decreased with both drugs, by 1.3 for captopril and 3.1 for atenolol, but the difference between the drugs was not significant 1.8; 95 confidence interval (Cl-13, 4.9. There was a significant increase in the reporting of cough and runny nose in those on captopril compared with atenolol. A health index increased by 1.1 with captopril in comparison with no change on atenolol (difference 1.1; 95 Cl — 2.0, 4.2). Psychological well-being was measured using the Symptom Rating Test. The improvement in total score was 1.4 with captopril and 2.3 with atenolol. The difference of 0.9 was not statistically significant (95 Cl - 1.2, 3.0). In the Symptom Rating Test subscales there was a tendency for atenolol to reduce anxiety more than captopril, — 0.6 units against — 0.1 units (difference 0.5 units, 95 Cl — 0.2, 1.2), for captopril to reduce depression more than atenolol, — 0.4 units against — 0.1 (difference 0.3, 95 Cl — 0.2, 1.2) and atenolol to reduce hostility more than captopril, - 0.7 against -0.2 (difference 0.5, 95 Cl - 0.3, 1.3). This trial on 125 patients followed for 2 months did not reveal any differences in quality of life between the two treatments. It is concluded that, overall, the quality-of-life measures during atenolol treatment were similar to those during captopril. However, important differences in measures of anxiety, depression and hostility could not be excluded with confidence.