This study was performed to compare the effects of two hydrophilic bile acids, taurohyodeoxycholic acid (THDCA) and tauroursodeoxycholic acid (TUDCA), on HepG2 cells. Cytotoxicity was evaluated at ...different times of exposure by incubating cells with increasing concentrations (50–800 μmol/l) of either bile acid, while their cytoprotective effect was tested in comparison with deoxycholic acid (DCA) (350 μmol/l and 750 μmol/l)-induced cytotoxicity. Culture media, harvested at the end of each incubation period, were analyzed to evaluate aspartate transaminase (AST), alanine transaminase and γ-glutamyltranspeptidase release. In addition, the hemolytic effect of THDCA and TUDCA on human red blood cells was also determined. At 24 h of incubation neither THDCA nor TUDCA was cytotoxic at concentrations up to 200 and 400 μmol/l. At 800 μmol/l both THDCA and TUDCA induced a slight increase in AST release. At this concentration and with time of exposure prolonged up to 72 h, THDCA and TUDCA induced a progressive increase of AST release significantly (
P<0.05) higher than that of controls being AST values for THDCA (2.97±0.88 time control value (tcv) at 48 h and 4.50±1.13 tcv at 72 h) significantly greater than those of TUDCA (1.50±0.20 tcv at 48 h and 1.80±0.43 tcv at 72 h) (
P<0.01). In cytoprotection experiments, the addition of 50 μmol/l THDCA decreased only slightly (−5%) AST release induced by 350 μmol/l DCA, while the addition of 50 μmol/l TUDCA was significantly effective (−23%;
P<0.05). Higher doses of THDCA or TUDCA did not reduce toxicity induced by 350 μmol/l DCA, but were much less toxic than an equimolar dose of DCA alone. At the concentration used in this experimental model neither THDCA nor TUDCA was hemolytic; however at a very high concentration (6 mmol/l) both bile acids induced 5–8% hemolysis. We conclude that bile acid molecules with a similar degree of hydrophilicity may show different cytotoxic and cytoprotective properties.
Regulation of bile acid synthesis, a key determinant of cholesterol homeostasis, is still incompletely understood. To elucidate the feedback control exerted on bile acid biosynthesis in humans with ...obstructive cholestasis, 16 patients with bile duct obstruction were studied. In vivo 7α-hydroxylation, reflecting bile acid synthesis, was assayed in 13 of them by tritium release analysis. Serum 27-hydroxycholesterol was determined by gas chromatography-mass spectrometry. In a subgroup, hepatic cholesterol 7α-hydroxylase mRNA was assayed by real-time polymerase chain reaction (PCR), enzyme activity was determined by isotope incorporation, and microsomal cholesterol content was assayed by gas chromatography–mass spectrometry. Age-matched control subjects were studied in parallel. Hydroxylation rates were lower in cholestatic patients (108 ± 33 mg of cholesterol per day, mean ± SEM; controls: 297 ± 40 mg/d; P < .01). The reduction was proportional to the severity of cholestasis, and synthetic rates were normalized in 4 subjects restudied after resolution of biliary obstruction. Consistent findings were obtained by analysis of serum 7α-hydroxycholesterol levels. On the other hand, hepatic cholesterol 7α-hydroxylase mRNA, microsomal enzyme activity, and cholesterol content tended to be increased in cholestasis. Finally, serum 27-hydroxycholesterol levels were slightly reduced in cholestatic subjects and were not related with the severity of the disease. Suppression of in vivo bile acid synthesis with no corresponding reduction in tissue 7α-hydroxylase expression and activity is consistent with nontranscriptional, posttranslational levels of regulation; these may play a role in the feedback control of bile acid synthesis in particular conditions. Alteration of the alternate biosynthetic pathway seems unlikely according to the present data. (HEPATOLOGY 2001;34:234-242.)
Several studies have shown that activin A is secreted in substantial amounts into the systemic circulation. The changes that occur during menstrual cycle and pregnancy suggest a correlation with ...reproductive function. At present, however, no definitive evidence has confirmed this pattern throughout adult life; moreover, neither the origin nor the physiological implications of this circulating growth factor have been clearly defined. The aim of the present study was to evaluate whether circulating concentrations of activin A change in adult men and women according to age and sex, and to examine the possible correlation with serum concentrations of FSH. Total dimeric activin A was measured using a specific two-site enzyme immunoassay in serum specimens collected from a cohort of normal individuals enrolled in an epidemiological survey. A group of men (n = 106) and one of women (n=151) were subdivided into six age groups (20-30, 30-40, 40-50, 50-60, 60-70 and 70-90 years). In a small group of 8 men and 11 women, serum concentrations of activin A were evaluated twice, in specimens collected at an interval of 10 years. Serum FSH concentrations were also measured in all specimens. Serum concentrations of activin A were not significantly different in men and women and showed an age-related progressive increase between 20 and 50 years of age (P<0.01, those aged 40-50 compared with those aged 20-30 years). After the age of 50 years, activin A concentrations remained in the same range of values in women, whereas they increased significantly in men, reaching peak values between 70 and 90 years (P<0.01 compared with the group aged between 20 and 50 years). From the age of 50 years, activin A concentrations were significantly greater in men compared with those in women in the corresponding age groups (P<0.001). Activin A concentrations correlated with age in men, but not in women. No significant correlation between concentrations of activin A and FSH was found in either sex. Activin A concentrations in specimens collected 10 years apart showed an increase in seven of eight men, but not in women. Finally, no significant variations of activin A concentrations were observed when fertile and postmenopausal women were compared. The present data indicate that circulating concentrations of activin A vary according to age; furthermore, men older than 50 years have greater concentrations than women. These changes, which occur irrespectively of FSH concentrations, indicate that circulating activin A is not a hormone of the reproductive axis.
Little is known about the relationships between hyperlipidemia and bile acid metabolism. However, hypolipidemic treatment with fibric acid derivatives has been shown to increase biliary cholesterol ...secretion, presumably by reducing bile acid synthesis. To clarify such relationships, we investigated the effects of different hyperlipoproteinemic conditions and of treatment with fibric acid derivatives on the rates of cholesterol 7 alpha-hydroxylation (the limiting step of bile acid synthesis) in humans. We studied 10 patients (aged 36 to 68 years) with lipoprotein phenotype IIa and with a clinical diagnosis of heterozygous familial hypercholesterolemia, a condition of reduced activity of LDL receptors, and 11 patients (aged 48 to 70 years) with lipoprotein phenotype IIb or IV and clinical diagnosis of familial combined hyperlipidemia, a condition probably related to increased hepatic lipoprotein synthesis. Cholesterol 7 alpha-hydroxylation rates were assayed in vivo by tritium release assay after an intravenous injection of 7 alpha-3Hcholesterol. The results were compared by ANOVA to the values obtained in a group of 28 normolipidemic patients (aged 34 to 83 years), with age as the covariate. Six patients were also studied after treatment with gemfibrozil (900 to 1200 mg/d for 6 to 8 weeks) and 5 patients were studied after treatment with bezafibrate (400 mg/d for 6 to 8 weeks). Hydroxylation rates were 0.82 +/- 0.22 mmol/d in the familial hypercholesterolemia group and 1.30 +/- 0.47 mmol/d in the familial combined hyperlipidemia group (P < .05 between the two groups and between patients with familial combined hyperlipidemia and control subjects; P = NS between patients with familial hypercholesterolemia and control subjects, as determined by ANOVA).
This study aimed to determine the effect in humans of taurohyodeoxycholic acid, a 6α‐hydroxylated bile acid with hydrophilic properties, on bile lipid secretion. Four cholecystectomized patients who ...had gallstones and an interrupted enterohepatic circulation were intraduodenally infused with taurohyodeoxycholic and tauroursodeoxycholic acids on separate occasions at a dose of 0.8 to 1 g/h for 3 hours. In hourly bile samples collected for 8 hours after the beginning of the infusion, biliary bile acid composition (by high‐performance liquid chromatography), biliary lipid concentrations (by standard methods), and distribution of biliary carriers (by gel chromatography) were evaluated. Blood liver function tests were performed before and after the infusions. Taurohyodeoxycholic and tauroursodeoxycholic acids became the predominant biliary bile acids in all patients except for one infused with taurohyodeoxycholic acid. Taurohyodeoxycholic acid stimulated significantly greater (P < .05) cholesterol and phospholipid secretion per unit of secreted bile acid (0.098 and 0.451 μmol/μmol, respectively) compared with tauroursodeoxycholic acid (0.061 μmol/μmol for cholesterol and 0.275 μmol/μmol for phospholipids). The secretory ratio between phospholipid and cholesterol was significantly higher after infusion of taurohyodeoxycholic acid (3.88 μmol/μmol) compared with taroursodeoxycholic acid (3.09 μmol/μmol) (P < .05). Biliary enrichment with taurohyodeoxycholic acid was positively related with percent concentration of phospholipids but not with that of cholesterol. The opposite trend was observed in tauroursodeoxycholic acid‐enriched biles. In both taurohyodeoxycholic acid‐ and tauroursodeoxycholic acid‐rich bile, 80% to 90% of cholesterol was carried in a gel‐chromatographic fraction corresponding to an apparent molecular weight of 80 to 200 kd. No alteration in liver function test results was observed after taurohyodeoxycholic acid infusion. In conclusion, taurohyodeoxycholic acid stimulates greater cholesterol and phospholipid secretion than tauroursodeoxycholic acid, but with a higher phospholipid/cholesterol secretory ratio. In bile enriched with both bile acids, biliary cholesterol is transported in non‐micellar aggregates. Finally, in the conditions of our study, taurohyodeoxycholic acid was not hepatotoxic.
To test whether de novo synthesis of cholesterol is a limiting factor for bile acid synthesis, we studied the acute effect of simvastatin, an inhibitor of HMG–coenzyme A reductase (the limiting step ...of cholesterol synthesis) on bile acid synthesis and biliary lipid secretion in subjects with interrupted enterohepatic circulation. In these conditions bile acid synthesis is derepressed and is assumed to equal biliary bile acid secretion. Five cholecystectomized patients fitted with T‐tubes were studied. All subjects were administered simvastatin (80 mg as a single dose) 5 days after surgery. Bile was collected in 3‐hr intervals for 15 hr before and 30 hr after the administration of the drug. During the experiment we kept the enterohepatic circulation of bile acid interrupted by inflating an occludable balloon inserted, during cholecystectomy, in the common bile duct. Simvastatin induced significant decreases of plasma total and low density lipoprotein cholesterol concentrations, from 163 ± 29 mg/dl and 97 ± 24 mg/dl of the pretreatment value to 144 ± 30 mg/dl and 82 ± 22 mg/dl 18 hr after simvastatin administration, respectively. Bile flow tended to increase after simvastatin, and the mean values from the third to the 15th hour after simvastatin administration (22.1 ± 1.9 ml/hr) were significantly greater than the mean values of the pretreatment period (19.9 ± 2.8 ml/hr). Concomitantly biliary bile acid, cholesterol and phospholipid concentrations fell from basal values of 15.9 ± 5.1, 2.3 ± 0.3 and 5.5 ± 0.3 mmol/L to mean values, after treatment, of 9.0 ± 3.5, 1.9 ± 0.5 and 3.0 ± 0.9 mmol/L, respectively. Cholesterol saturation index increased from a mean value of 1.51 ± 0.31 in the pretreatment period to 1.98 ± 0.52 after simvastatin. Bile acid output decreased from a mean pretreatment value of 308.0 ± 79.1 μmol/hr to 191.9 ± 69.2 μmol/hr after simvastatin administration. Secretion rates of phospholipids decreased to a lesser extent, whereas cholesterol output remained constant. No correlation was found between bile acid output and bile flow, phospholipid secretion and cholesterol secretion. A significant correlation was present between phospholipid and cholesterol secretion. Our data show that, in conditions of derepressed bile acid synthesis, acute inhibition of HMG–coenzyme A reductase activity induces decreased bile acid synthesis and excretion. Our findings may suggest that the availability of newly synthesized cholesterol is a critical factor for bile acid synthesis and secretion but not for cholesterol secretion; alternatively HMG–coenzyme A reductase and cholesterol 7α‐hydroxylase, the rate‐limiting step of bile acid synthesis, may be coordinately regulated at the transcriptional level. (HEPATOLOGY 1994;19:882–888.)
Background and aims: Herpesviruses infect the liver and cause minor hepatitis. Our aim is to verify the presence of herpesviruses in the liver from hepatitis C patients and the possible influence of ...these viruses in the liver disease.
Methods: We searched for herpesvirus DNA in liver biopsies from patients with hepatitis C and from a control group without hepatitis by means of nested polymerase chain reaction. Serological investigations were carried out as well.
Results: Thirty-four liver specimens from hepatitis C patients were examined, 12 of which (35.3%) were positive for at least one herpesvirus DNA, whereas among the 19 control specimens only two were positive (10.5%;
P=0.049). Liver biopsies from seven patients, three with acute hepatitis of unknown origin, three with non-alcoholic steatohepatitis and one with autoimmune hepatitis were also investigated and three positive samples were found.
Conclusions: The prevalence of herpesvirus DNA was found higher in patients with hepatitis C than in individuals without hepatitis. The influence of herpesviruses on the clinical course of hepatitis C is considered.
To test whether
de novo synthesis of cholesterol is a limiting factor for bile acid synthesis, we studied the acute effect of simvastatin, an inhibitor of HMG-coenzyme A reductase (the limiting step ...of cholesterol synthesis) on bile acid synthesis and biliary lipid secretion in subjects with interrupted enterohepatic circulation. In these conditions bile acid synthesis is derepressed and is assumed to equal biliary bile acid secretion. Five cholecystectomized patients fitted with ⊇-tubes were studied. All subjects were administered simvastatin (80 mg as a single dose) 5 days after surgery. Bile was collected in 3-hr intervals for 15 hr before and 30 hr after the administration of the drug. During the experiment we kept the enterohepatic circulation of bile acid interrupted by inflating an occuludable balloon inserted, during cholecystectomy, in the common bile duct. Simvastatin induced significant decreases of plasma total and low density lipoprotein cholesterol concentrations, from 163 ± 29 mg/dl and 97 ± 24 mg/dl of the pretreatment value to 144 ± 30 mg/dl and 82 ± 22 mg/dl 18 hr after simvastatin administration, respectively. Bile flow tended to increase after simvastatin, and the mean values from the third to the 15th hour after simvastatin administration (22.1 ± 1.9 ml/hr) were significantly greater than the mean values of the pretreatment period (19.9 ± 2.8 ml/hr). Concomitantly biliary bile acid, cholesterol and phospholipid concentrations fell from basal values of 15.9 ± 5.1, 2.3 ± 0.3 and 5.5 ± 0.3 mmol/L to mean values, after treatment, of 9.0 ± 3.5, 1.9 ± 0.5 and 3.0 ± 0.9 mmol/L, respectively. Cholesterol saturation index increased from a mean value of 1.51 ± 0.31 in the pretreatment period to 1.98 ± 0.52 after simvastatin. Bile acid output decreased from a mean pretreatment value of 308.0 ± 79.1 μmol/hr to 191.9 ± 69.2 μmol/hr after simvastatin administration. Secretion rates of phospholipids decreased to a lesser extent, whereas cholesterol output remained constant. No correlation was found between bile acid output and bile flow, phospholipid secretion and cholesterol secretion. A significant correlation was present between phospholipid and cholesterol secretion. Our data show that, in conditions of derepressed bile acid synthesis, acute inhibition of HMG-coenzyme A reductase activity induces decreased bile acid synthesis and excretion. Our findings may suggest that the availability of newly synthesized cholesterol is a critical factor for bile acid synthesis and secretion but not for cholesterol secretion; alternatively HMG-coenzyme A reductase and cholesterol 7α-hydroxylase, the rate-limiting step of bile acid synthesis, may be coordinately regulated at the transcriptional level.
Introduction:
Recent anticoagulant intake represents a contraindication for thrombolysis in acute ischemic stroke. Idarucizumab reverses the anticoagulant effect of dabigatran, potentially allowing ...for thrombolysis. This nation-wide observational cohort study, systematic review, and meta-analysis evaluated the efficacy and safety of thrombolysis preceded by dabigatran-reversal in people with acute ischemic stroke.
Patients and methods:
We recruited people undergoing thrombolysis following dabigatran-reversal at 17 stroke centers in Italy (reversal-group), people on dabigatran treated with thrombolysis without reversal (no-reversal group), and age, sex, hypertension, stroke severity, and reperfusion treatment-matched controls in 1:7 ratio (control-group). We compared groups for symptomatic intracranial hemorrhage (sICH, main outcome), any brain hemorrhage, good functional outcome (mRS 0–2 at 3 months), and death. The systematic review followed a predefined protocol (CRD42017060274), and odds ratio (OR) meta-analysis was implemented to compare groups.
Results:
Thirty-nine patients in dabigatran-reversal group and 300 matched controls were included. Reversal was associated with a non-significant increase in sICH (10.3% vs 6%, aOR = 1.32, 95% CI = 0.39–4.52), death (17.9% vs 10%, aOR = 0.77, 95% CI = 0.12–4.93) and good functional outcome (64.1% vs 52.8%, aOR = 1.41, 95% CI = 0.63–3.19). No hemorrhagic events or deaths were registered in no-reversal group (n = 12). Pooling data from 3 studies after systematic review (n = 1879), reversal carried a non-significant trend for sICH (OR = 1.53, 95% CI = 0.67–3.50), death (OR = 1.53, 95% CI = 0.73–3.24) and good functional outcome (OR = 2.46, 95% CI = 0.85–7.16).
Discussion and conclusion:
People treated with reperfusion strategies after dabigatran reversal with idarucizumab seem to have a marginal increase in the risk of sICH but comparable functional recovery to matched patients with stroke. Further studies are needed to define treatment cost-effectiveness and potential thresholds in plasma dabigatran concentration for reversal.
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