Increased Bile Acid Concentrations Research Articles

Interruption of bile acid uptake by hepatocytes after acetaminophen overdose ameliorates hepatotoxicity

Background & AimsAcetaminophen (APAP) overdose remains a frequent cause of acute liver failure, which is generally accompanied by increased levels of serum bile acids (BAs). However, the pathophysiological role of BAs remains elusive. Herein, we investigated the role of BAs in APAP-induced hepatotoxicity.MethodsWe performed intravital imaging to investigate BA transport in mice, quantified endogenous BA concentrations in the serum of mice and patients with APAP overdose, analyzed liver tissue and bile by mass spectrometry and MALDI-mass spectrometry imaging, assessed the integrity of the blood-bile barrier and the role of oxidative stress by immunostaining of tight junction proteins and intravital imaging of fluorescent markers, identified the intracellular cytotoxic concentrations of BAs, and performed interventions to block BA uptake from blood into hepatocytes.ResultsPrior to the onset of cell death, APAP overdose causes massive oxidative stress in the pericentral lobular zone, which coincided with a breach of the blood-bile barrier. Consequently, BAs leak from the bile canaliculi into the sinusoidal blood, which is then followed by their uptake into hepatocytes via the basolateral membrane, their secretion into canaliculi and repeated cycling. This, what we termed ‘futile cycling’ of BAs, led to increased intracellular BA concentrations that were high enough to cause hepatocyte death. Importantly, however, the interruption of BA re-uptake by pharmacological NTCP blockage using Myrcludex B and Oatp knockout strongly reduced APAP-induced hepatotoxicity.ConclusionsAPAP overdose induces a breach of the blood-bile barrier which leads to futile BA cycling that causes hepatocyte death. Prevention of BA cycling may represent a therapeutic option after APAP intoxication.Lay summaryOnly one drug, N-acetylcysteine, is approved for the treatment of acetaminophen overdose and it is only effective when given within ∼8 hours after ingestion. We identified a mechanism by which acetaminophen overdose causes an increase in bile acid concentrations (to above toxic thresholds) in hepatocytes. Blocking this mechanism prevented acetaminophen-induced hepatotoxicity in mice and evidence from patients suggests that this therapy may be effective for longer periods after ingestion compared to N-acetylcysteine.

ENDOCRINOLOGY IN PREGNANCY: Metabolic impact of bile acids in gestation.

Bile acids are lipid-solubilising molecules that also regulate metabolic processes. Farnesoid X receptor (FXR) and Takeda G-protein coupled receptor 5 (TGR5) are two bile acid receptors with key metabolic roles. FXR regulates bile acid synthesis in the liver and influences bile acid uptake in the intestine. TGR5 is mainly involved in regulation of signalling pathways in response to bile acid uptake in the gut and therefore prandial response. Both FXR and TGR5 have potential as therapeutic targets for disorders of glucose and/or lipid homeostasis. Gestation is also known to cause small increases in bile acid concentrations, but physiological hypercholanaemia of pregnancy is usually not sufficient to cause any clinically relevant effects. This review focuses on how gestation alters bile acid homeostasis, which can become pathological if the elevation of maternal serum bile acids is more marked than physiological hypercholanaemia, and on the influence of FXR and TGR5 function in pregnancy on glucose and lipid metabolism. This will be discussed with reference to two gestational disorders: intrahepatic cholestasis of pregnancy (ICP), a disease where bile acids are pathologically elevated, and gestational diabetes mellitus (GDM), characterised by hyperglycaemia during pregnancy.

The severity of intrahepatic cholestasis of pregnancy can shorten the first stage of labor in multiparous women induced by prostaglandin E2

Aim: To determine the relationship between increased serum bile acid concentrations and the first stage of labor in multiparous women induced by vaginal prostaglandin E2 (PGE2) with intrahepatic cholestasis of pregnancy (ICP). Material and Methods: In this retrospective case-control study 283 multiparous women with ICP and 283 healthy multiparous pregnant women were admitted for induction of delivery, were inserted PGE2 (10 mg dinoprostone) vaginally. The groups with mild, moderate and severe ICP were compared with control group in terms of the time from beginning of PGE2 vaginal insertion to active phase of labor, the time from beginning of PGE2 vaginal insertion to complete dilatation of cervix and fetal outcomes. Results: The time from beginning of PGE2 insertion to active phase in the mild, moderate and severe ICP groups were shorter than in the non-ICP group; 3.19±0.32, 7.26±0.34, 8.71±0.35 hours, respectively (p<0.01). The time from beginning of PGE2 insertion to complete dilatation of cervix in the groups with mild, moderate and severe ICP were shorter than in non-ICP group; 3.03 ± 0.45; 10.33 ± 0.62; 14.44 ± 0.53, respectively (p<0.01). There was no difference between the groups in terms of fetal outcomes except fetal weight and the presence of meconium (p<0.01). Conclusion: Increased bile acid concentrations in multiparous pregnant women induced by vaginal PGE2 with mild, moderate and severe ICP are associated with shorter duration of cervical ripening and labor induction time to delivery. The study concluded that multiparous women with ICP can deliver faster as the severity of cholestasis increases.

Ursodeoxycholic acid inhibits hepatic cystogenesis in experimental models of polycystic liver disease

Polycystic liver diseases (PLDs) are genetic disorders characterized by progressive biliary cystogenesis. Current therapies show short-term and/or modest beneficial effects. Cystic cholangiocytes hyperproliferate as a consequence of diminished intracellular calcium levels ([Ca(2+)]i). Here, the therapeutic value of ursodeoxycholic acid (UDCA) was investigated. Effect of UDCA was examined in vitro and in polycystic (PCK) rats. Hepatic cystogenesis and fibrosis, and the bile acid (BA) content were evaluated from the liver, bile, serum, and kidneys by HPLC-MS/MS. Chronic treatment of PCK rats with UDCA inhibits hepatic cystogenesis and fibrosis, and improves their motor behaviour. As compared to wild-type animals, PCK rats show increased BA concentration ([BA]) in liver, similar hepatic Cyp7a1 mRNA levels, and diminished [BA] in bile. Likewise, [BA] is increased in cystic fluid of PLD patients compared to their matched serum levels. In PCK rats, UDCA decreases the intrahepatic accumulation of cytotoxic BA, normalizes their diminished [BA] in bile, increases the BA secretion in bile and diminishes the increased [BA] in kidneys. In vitro, UDCA inhibits the hyperproliferation of polycystic human cholangiocytes via a PI3K/AKT/MEK/ERK1/2-dependent mechanism without affecting apoptosis. Finally, the presence of glycodeoxycholic acid promotes the proliferation of polycystic human cholangiocytes, which is inhibited by both UDCA and tauro-UDCA. UDCA was able to halt the liver disease of a rat model of PLD through inhibiting cystic cholangiocyte hyperproliferation and decreasing the levels of cytotoxic BA species in the liver, which suggests the use of UDCA as a potential therapeutic tool for PLD patients.

The physiology underlying Roux-en-Y gastric bypass: a status report.

Obesity and its related comorbidities can be detrimental for the affected individual and challenge public health systems worldwide. Currently, the only available treatment options leading to clinically significant and maintained body weight loss and reduction in obesity-related morbidity and mortality are based on surgical interventions. This review will focus on two main clinical effects of Roux-en-Y gastric bypass (RYGB), namely body weight loss and change in eating behavior. Animal experiments designed to understand the underlying physiological mechanisms of these post-gastric bypass effects will be discussed. Where appropriate, reference will also be made to vertical sleeve gastrectomy. While caloric malabsorption and mechanical restriction seem not to be major factors in this respect, alterations in gut hormone levels are invariably found after RYGB. However, their causal role in RYGB effects on eating and body weight has recently been challenged. Other potential factors contributing to the RYGB effects include increased bile acid concentrations and an altered composition of gut microbiota. RYGB is further associated with remarkable changes in preference for different dietary components, such as a decrease in the preference for high fat or sugar. It needs to be noted, however, that in many cases, the question about the necessity of these alterations for the success of bariatric surgery procedures remains unanswered.

Hyperammonemic Encephalopathy Associated with Portal Vein Thrombosis in a Thoroughbred Foal

Hyperammonemic Encephalopathy Associated with Portal Vein Thrombosis in a Thoroughbred Foal

Beneficial effect of sulphate-bicarbonate-calcium water on gallstone risk and weight control

To investigate the effect of drinking sulphate-bicarbonate-calcium thermal water (TW) on risk factors for atherosclerosis and cholesterol gallstone disease. Postmenopausal women with functional dyspepsia and/or constipation underwent a 12 d cycle of thermal (n = 20) or tap (n = 20) water controlled drinking. Gallbladder fasting volume at ultrasound, blood vitamin E, oxysterols (7-β-hydroxycholesterol and 7-ketocholesterol), bile acid (BA), triglycerides, total/low density lipoprotein and high density lipoprotein cholesterol were measured at baseline and at the end of the study. Food consumption, stool frequency and body weight were recorded daily. Blood lipids, oxysterols and vitamin E were not affected by either thermal or tap water consumption. Fasting gallbladder volume was significantly (P < 0.005) smaller at the end of the study than at baseline in the TW (15.7 ± 1.1 mL vs 20.1 ± 1.7 mL) but not in the tap water group (19.0 ± 1.4 mL vs 19.4 ± 1.5 mL). Total serum BA concentration was significantly (P < 0.05) higher at the end of the study than at baseline in the TW (5.83 ± 1.24 μmol vs 4.25 ± 1.00 μmol) but not in the tap water group (3.41 ± 0.46 μmol vs 2.91 ± 0.56 μmol). The increased BA concentration after TW consumption was mainly accounted for by glycochenodeoxycholic acid. The number of pasta (P < 0.001), meat (P < 0.001) and vegetable (P < 0.005) portions consumed during the study and of bowel movements per day (P < 0.05) were significantly higher in the TW than in the tap water group. Body weight did not change at the end of the study as compared to baseline in both groups. Sulphate-bicarbonate-calcium water consumption has a positive effect on lithogenic risk and intestinal transit and allows maintenance of a stable body weight despite a high food intake.

Rapid quantification of conjugated and unconjugated bile acids and C27 precursors in dried blood spots and small volumes of serum

The aim of the study was to develop a method for fast and reliable diagnosis of peroxisomal diseases and to facilitate differential diagnosis of cholestatic hepatopathy. For the quantification of bile acids and their conjugates as well as C(27) precursors di- and trihydroxycholestanoic acid (DHCA, THCA), in small pediatric blood samples we combined HPLC separation on a reverse-phase C18 column with ESI-MS/MS analysis in the negative ion mode. Analysis was done with good precision (CV 3,7%-11.1%) and sufficient sensitivity (LOQ: 11-91 nmol/L) without derivatization. Complete analysis of 17 free and conjugated bile acids from dried blood spots and 10 microL serum samples, respectively, was performed within 12 min. Measurement of conjugated primary bile acids plus DHCA and THCA as well as ursodeoxycholic acid was done in 4.5 min. In blood spots of healthy newborns, conjugated primary bile acids were found in the range of 0.01 to 2.01 micromol/L. Concentrations of C(27) precursors were below the detection limit in normal controls. DHCA and THCA were specifically elevated in cases of peroxysomal defects and one Zellweger patient.

High protein intake reduces intrahepatocellular lipid deposition in humans

Background:High sugar and fat intakes are known to increase intrahepatocellular lipids (IHCLs) and to cause insulin resistance. High protein intake may facilitate weight loss and improve glucose homeostasis in insulin-resistant patients, but its effects on IHCLs remain unknown.Objective:The aim was to assess the effect of high protein intake on high-fat diet–induced IHCL accumulation and insulin sensitivity in healthy young men.Design:Ten volunteers were studied in a crossover design after 4 d of either a hypercaloric high-fat (HF) diet; a hypercaloric high-fat, high-protein (HFHP) diet; or a control, isocaloric (control) diet. IHCLs were measured by 1H-magnetic resonance spectroscopy, fasting metabolism was measured by indirect calorimetry, insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp, and plasma concentrations were measured by enzyme-linked immunosorbent assay and gas chromatography–mass spectrometry; expression of key lipogenic genes was assessed in subcutaneous adipose tissue biopsy specimens.Results:The HF diet increased IHCLs by 90 ± 26% and plasma tissue-type plasminogen activator inhibitor-1 (tPAI-1) by 54 ± 11% (P< 0.02 for both) and inhibited plasma free fatty acids by 26 ± 11% and β-hydroxybutyrate by 61 ± 27% (P< 0.05 for both). The HFHP diet blunted the increase in IHCLs and normalized plasma β-hydroxybutyrate and tPAI-1 concentrations. Insulin sensitivity was not altered, whereas the expression of sterol regulatory element-binding protein-1c and key lipogenic genes increased with the HF and HFHP diets (P< 0.02). Bile acid concentrations remained unchanged after the HF diet but increased by 50 ± 24% after the HFHP diet (P= 0.14).Conclusions:Protein intake significantly blunts the effects of an HF diet on IHCLs and tPAI-1 through effects presumably exerted at the level of the liver. Protein-induced increases in bile acid concentrations may be involved. This trial was registered at www.clinicaltrials.govas NCT00523562.

Effect of cholic acid and its keto derivatives on the analgesic action of lidocaine and associated biochemical parameters in rats

This study examined the effect of the structure and concentration of cholic acid and its keto derivatives on the local analgesic action of lidocaine in rats, measured by an analgesimetric method. The increase in bile acid concentrations in the administered lidocaine solution increased the duration of local anesthesia. It was found that the introduction of keto groups into the cholic acid molecule yielded derivatives with lower promotory action, i.e. decreased the duration of local anesthesia. The biochemical parameters investigated indicated that the keto derivatives of cholic acid exhibited no toxicity compared to that of cholic acid itself.

High Complication Rate of an Automatic Tru‐Cut Biopsy Gun Device for Liver Biopsy in Cats

Background:Liver biopsies taken with an automatic Tru‐Cut biopsy gun device caused unexpected fatal shock reactions in cats. The goal of the present study was to determine if this biopsy device caused more frequent fatal complications than did a semiautomatic device.Animals: All cats referred to the Utrecht University, between October 1, 2002, and October 31, 2004, in which ultrasound‐guided Tru‐Cut liver biopsies were taken. The indications for liver biopsy were increased liver enzyme activity, increased bile acid concentrations, ultrasonographic abnormalities of the liver, ultrasonographic abnormalities of the bile ducts, or some combination of these findings. Coagulation parameters were normal.Methods: From October 1, 2002, until October 31, 2003, 26 cats were biopsied with an automatic biopsy device. Between November 1, 2003, and October 31, 2004, 19 cats underwent liver biopsy with a semiautomatic biopsy device.Results: In the first period, 5 of the 26 cats (19%) developed severe shock within 15 minutes. Resuscitation was not successful. In the second period, none of the 19 cats experienced any major adverse effect. There were no significant differences between the 2 groups with respect to diagnosis, clinical signs, clinicopathologic findings, or the use of anesthetics.Conclusions and Clinical Importance: We conclude that the difference in complication rate is explained by the biopsy technique used. The pressure wave, which occurs when firing the automatic device, may have caused intense vagotonia and shock. Use of this automatic biopsy device should be avoided in cats because of the high risk of fatal complications.

High Complication Rate of an Automatic Tru-Cut Biopsy Gun Device for Liver Biopsy in Cats

Liver biopsies taken with an automatic Tru-Cut biopsy gun device caused unexpected fatal shock reactions in cats. The goal of the present study was to determine if this biopsy device caused more frequent fatal complications than did a semiautomatic device. All cats referred to the Utrecht University, between October 1, 2002, and October 31, 2004, in which ultrasound-guided Tru-Cut liver biopsies were taken. The indications for liver biopsy were increased liver enzyme activity, increased bile acid concentrations, ultrasonographic abnormalities of the liver, ultrasonographic abnormalities of the bile ducts, or some combination of these findings. Coagulation parameters were normal. From October 1, 2002, until October 31, 2003, 26 cats were biopsied with an automatic biopsy device. Between November 1, 2003, and October 31, 2004, 19 cats underwent liver biopsy with a semiautomatic biopsy device. In the first period. 5 of the 26 cats (19%) developed severe shock within 15 minutes. Resuscitation was not successful. In the second period, none of the 19 cats experienced any major adverse effect. There were no significant differences between the 2 groups with respect to diagnosis, clinical signs, clinicopathologic findings, or the use of anesthetics. We conclude that the difference in complication rate is explained by the biopsy technique used. The pressure wave, which occurs when firing the automatic device, may have caused intense vagotonia and shock. Use of this automatic biopsy device should be avoided in cats because of the high risk of fatal complications.

Complementary Stimulation of Hepatobiliary Transport and Detoxification Systems by Rifampicin and Ursodeoxycholic Acid in Humans

Rifampicin (RIFA) and ursodeoxycholic acid (UDCA) improve symptoms and biochemical markers of liver injury in cholestatic liver diseases by largely unknown mechanisms. We aimed to study the molecular mechanisms of action of these drugs in humans. Thirty otherwise healthy gallstone patients scheduled for cholestectomy were randomized to RIFA (600 mg/day for 1 week) or UDCA (1 g/day for 3 weeks) or no medication before surgery. Routine biochemistry, lipids, and surrogate markers for P450 activity (4beta-hydroxy cholesterol, 4beta-OH-C) and bile acid synthesis (7alpha-hydroxy-4-cholesten-3-one, C-4) were measured in serum. Bile acids were analyzed in serum, urine, and bile. A wedge liver biopsy specimen was taken to study expression of hepatobiliary ABC transporters as well as detoxification enzymes and regulatory transcription factors. RIFA enhanced bile acid detoxification as well as bilirubin conjugation and excretion as reflected by enhanced expression of CYP3A4, UGT1A1, and MRP2. These molecular effects were paralleled by decreased bilirubin and deoxycholic acid concentrations in serum and decreased lithocholic and deoxycholic acid concentrations in bile. UDCA on the other hand stimulated the expression of BSEP, MDR3, and MRP4. UDCA became the predominant bile acid after UDCA treatment and lowered the biliary cholesterol saturation index. RIFA enhances bile acid detoxification as well as bilirubin conjugation and export systems, whereas UDCA stimulates the expression of transporters for canalicular and basolateral bile acid export as well as the canalicular phospholipid flippase. These independent but complementary effects may justify a combination of both agents for the treatment of cholestatic liver diseases.

Disrupted coordinate regulation of farnesoid X receptor target genes in a patient with cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX), sterol 27-hydroxylase (CYP27A1) deficiency, is associated with markedly reduced chenodeoxycholic acid (CDCA), the most powerful activating ligand for farnesoid X receptor (FXR). We investigated the effects of reduced CDCA on FXR target genes in humans. Liver specimens from an untreated CTX patient and 10 control subjects were studied. In the patient, hepatic CDCA concentration was markedly reduced but the bile alcohol level exceeded CDCA levels in control subjects (73.5 vs. 37.8 +/- 6.2 nmol/g liver). Cholesterol 7alpha-hydroxylase (CYP7A1) and Na+/taurocholate-cotransporting polypeptide (NTCP) were upregulated 84- and 8-fold, respectively. However, small heterodimer partner (SHP) and bile salt export pump were normally expressed. Marked CYP7A1 induction with normal SHP expression was not explained by the regulation of liver X receptor alpha (LXRalpha) or pregnane X receptor. However, another nuclear receptor, hepatocyte nuclear factor 4alpha (HNF4alpha), was induced 2.9-fold in CTX, which was associated with enhanced mRNA levels of HNF4alpha target genes, CYP7A1, 7alpha-hydroxy-4-cholesten-3-one 12alpha-hydroxylase, CYP27A1, and NTCP. In conclusion, the coordinate regulation of FXR target genes was lost in CTX. The mechanism of the disruption may be explained by a normally stimulated FXR pathway attributable to markedly increased bile alcohols with activation of HNF4alpha caused by reduced bile acids in CTX liver.

Acquired Portosystemic Shunting in 2 Cats Secondary to Congenital Hepatic Fibrosis

Case 1. A 2-year-old female crossbred cat was referred to Utrecht University Companion Animal Clinic with a 2-month history of episodic vomiting, constipation, decreased appetite, apathy, and decreased activity. The vomiting was treated successfully with cisapride (0.25 mg/kg PO q8h). Physical examination disclosed no abnormalities and a full CBC and serum biochemistry tests were performed. These evaluations showed a leukocytosis (18.6 3 109/L; reference range, 4.3–16.2 3 109/L), increased bile acid concentration (132 mmol/L [53.88 mg/mL]; reference range, 1– 13 mmol/L) and a low BUN concentration (3.6 mmol/L [10.08 mg/dL]; reference range, 6.1–12.8 mmol/L). The combination of high bile-acid concentration and low BUN concentration indicated possible portosystemic shunting. Fasting venous blood ammonia concentration was measured and was increased (196 mmol/L [354 mg/dL]; reference range, ,50 mmol/L). Abdominal ultrasonography was performed for the further diagnosis and identification of portosystemic shunting. Abdominal ultrasonography revealed several small cortical cysts in both kidneys compatible with polycystic kidney disease (PKD). Otherwise, the size and structure of both kidneys and the liver were considered normal. An anomalous tortuous vessel with hepatofugal flow was seen originating from the portal vein in the region where the splenic vein enters the trunk of the portal vein. It was not possible to follow the shunting vessel to its termination. The direction of blood flow was hepatofugal in the portal vein cranial to the origin of the anomalous vein and was hepatopetal caudal to it. The left ovarian vein was dilated. A very small amount of free abdominal fluid was seen. The spleen was ultrasonographically normal. The tortuous anomalous vein was suspected to be an acquired portosystemic collateral, therefore ultrasound-guided core biopsiesa of the liver were taken. The liver biopsies were processed routinely and stained with hematoxylin-eosin, Von Gieson, and a reticulin stain according to the method of Gordon and Sweet. Histological

Thirteen-Week Inhalation Toxicity of 2- and 4-Chloronitrobenzene in F344/N Rats and B6C3F1 Mice

Toxicity studies were performed by exposing F344/N rats and B6C3F1 mice to 2- and 4-chloronitrobenzene (CNB) by whole-body inhalation 6 hr/day, 5 days/week, for 13 weeks. Animals were evaluated for clinical chemistry (rats), hematology (rats), histopathology, and body/organ weights. Exposure concentrations were 0, 1.1, 2.3, 4.5, 9, and 18 ppm for 2-CNB and 0, 1.5, 3, 6, 12, and 24 ppm for 4-CNB. All rats in the 2-CNB study survived until the end of the study. Two male mice in the 18-ppm group in the 2-CNB study, however, died during Week 12; no deaths attributable to 4-CNB exposure occurred in rats or mice. In both studies, the mean body weight gains of exposed animals were similar to those of the respective controls. In rats, inhalation exposure to 2- or 4-CNB resulted in methemoglobinemia leading to a regenerative anemia and a variety of tissue changes secondary to the oxidative erythrocyte injury. In the 2-CNB study, methemoglobinemia resulted in a normocytic, normochromic, responsive anemia, whereas with 4-CNB, the methemoglobinemia was more severe and resulted in a macrocytic, hyperchromic, responsive anemia. Alterations of erythrocyte morphology were observed in both studies; changes included Heinz bodies, poikilocytes, and polychromasia. In rats, both isomers caused increases in serum activities of alanine aminotransferase and sorbitol dehydrogenase and increased bile acid concentrations. Microscopic liver changes included hemosiderin deposition in Kupffer cells (rats and mice exposed to 4-CNB), hepatocytomegaly (mice), and cytoplasmic basophilia (rats). Hepatocellular necrosis and chronic inflammation observed in mice were rather specific to the 2-CNB isomer, as only slight evidence of focal necrosis in the liver was observed in mice exposed to 4-CNB. Splenic lesions included hemosiderin accumulation, capsular fibrosis, and increased hematopoietic cell proliferation. Increased bone marrow hemosiderin and hematopoietic cell proliferation and kidney tubule hemosiderin deposition were also observed. Other findings, attributed to chemical exposure but not to the hematotoxicity, were described. Lesions included hyaline droplet nephropathy and degeneration of the testis in male rats exposed to 4-CNB, inflammation of the harderian gland in rats exposed to 4-CNB, hyperplasia of the nasal cavity epithelium in rats exposed to 2-CNB, and hyperplasia of the forestomach epithelium in mice exposed to 4-CNB; these lesions have not been described previously in studies with these chemicals. Based on the exposure concentrations evaluated, A no-observed-adverse-effect level (NOAEL) for histopathological injury in mice was 4.5 ppm for 2-chloronitrobenzene and 6 ppm for 4-chloronitrobenzene; a NOAEL was not determined for rats.

Biliary lipid composition and bile acid profiles during and after enteral fast of total parenteral nutrition in the rabbit.

Feeding and fasting influence biliary lipid composition. With total parenteral nutrition (TPN), it is possible to study the effects of a long-term "enteral fast" on biliary lipid composition without the metabolic ill-effects of nutrient deprivation. We compared the lipid and bile acid (BA) contents of hepatic and gallbladder biles in rabbits on completion of a 14-day regimen of TPN with those in rabbits returned to oral feeds for 6 weeks after a similar spell of TPN. Chow-fed rabbits served as controls. With TPN, plasma phospholipid and cholesterol levels were elevated. Basal bile flow and the secretion of bile acids and phospholipids were decreased in the TPN and post-TPN groups, while the cholesterol secretion rate was essentially unchanged. During TPN, the molar percent of cholesterol (relative to bile acids and phospholipid) in hepatic bile was increased. Biliary glycolithocholic acid (GLCA; as a percent of total conjugated BA) in hepatic bile increased from 1.7% (0.9% SEM) in the chow-fed to 8.5% (1.5% SEM) during TPN. In TPN and post-TPN groups, the gallbladder was enlarged to more than twice normal (chow-fed) size, and contained a dark, mucoid bile (biliary sludge). In this bile, (a) there was a 2.5-fold increase in bile acid concentration; and (b) the molar percent of cholesterol decreased while that of bile acids increased. TPN produced a state of functional cholestasis, which extended into the post-TPN period. Gallbladder distension was the common denominator of the hepatobiliary dysfunction in the TPN and post-TPN rabbits. With sequestration of bile acids in the gallbladder during and after TPN, the circulating bile acid pool was constricted, and the enterohepatic circulation impaired. As cholesterol secretion was low at all times, cholesterol supersaturation did not occur. The molar percent of cholesterol in gallbladder bile decreased, while that of bile acids increased; this suggests absorption of cholesterol by gallbladder mucosa. The increase in biliary GLCA probably resulted from bacterial biotransformation of glycochenodeoxycholic acid to lithocholic acid and its increased absorption from the cecum during TPN.

Hematological and Blood Biochemical Effects of Fasting and Subsequent Oral Administration of Endotoxin in Prepubertal Gilts

The main objective of the present study was to investigate the effects of short-term fasting in gilts on endocrinological and blood biochemical parameters and, further, the effects of subsequent oral endotoxin (ET) administration. Group 1 was fasted for 30 h and then received feed with ET added. Group 2 was fasted for 30 h but received standard feed at refeeding. In group 3, gilts were fed every 6 h for 30 h. The major effects of fasting were: gradually increased concentration of plasma prostaglandin F2α metabolite, serum total bilirubin, serum free fatty acids, and decreased serum glucose. The values were normalized within 1–4 h of refeeding. Twelve hours after refeeding, the ET-refed gilts showed higher levels of serum total bile acids and polymorphonuclear leukocytes than those in group 2. It is possible that the observed changes during fasting reflect either an increased intestinal uptake of naturally present endotoxin or a reduced endotoxin detoxifying capacity of the liver. The increased bile acid concentration and polymorphonuclear leukocyte count following refeeding with ET-feed may indicate that orally administered ET is to some extent absorbed from the gut.

Increased bile acid concentration in liver tissue with cholesterol gallstone disease.

Patients with cholesterol gallstone disease have a reduced pool of bile acids. Overly sensitive feedback inhibition of bile acid synthesis has been postulated to explain this size reduction. To test this hypothesis, hepatic bile acid concentration and the activity of cholesterol 7 alpha-hydroxylase, the rate-limiting enzyme for bile acid biosynthesis, were determined in ten patients with cholesterol gallstones and ten patients without gallstones. The bile acids present in liver tissue are the sum of those returning to liver and those newly synthesized in liver. If an overly sensitive feedback inhibition truly existed in our gallstone patients, a decreased concentration of hepatic bile acids would have been expected. However, patients with cholesterol gallstones had significantly higher total (143.3 +/- 25.5 vs 64.5 +/- 10.8 nmol/g liver, P < 0.01), chenodeoxycholic (64.1 +/- 9.9 vs 29.8 +/- 5.4, P < 0.01), deoxycholic (22.8 +/- 10.9 vs 2.0 +/- 0.7, P < 0.05), and ursodeoxycholic acid (6.2 +/- 1.4 vs 1.5 +/- 0.6, P < 0.01) concentrations than patients without gallstones. The activity of cholesterol 7 alpha-hydroxylase did not differ significantly between the two groups. Impaired hepatic transport or secretion of bile acids is strongly suspected in cholesterol gallstone patients. The findings of the present study showed no evidence of overly sensitive feedback inhibition of bile acid synthesis in cholesterol gallstone patients. Bile acid pool size may be affected by the inappropriate increase of hepatic bile acids rather than by overly sensitive feedback inhibition.

The occurrence of somatomedin C in daunorubicin-induced cardiomyopathy in rabbits

Toxicity studies were performed by exposing F344/N rats and B6C3F1 mice to 2- and 4-chloronitrobenzene (CNB) by whole-body inhalation 6 hr/day, 5 days/week, for 13 weeks. Animals were evaluated for clinical chemistry (rats), hematology (rats), histopathology, and body/organ weights. Exposure concentrations were 0, 1.1, 2.3, 4.5, 9, and 18 ppm for 2-CNB and 0, 1.5, 3, 6, 12, and 24 ppm for 4-CNB. All rats in the 2-CNB study survived until the end of the study. Two male mice in the 18-ppm group in the 2-CNB study, however, died during Week 12; no deaths attributable to 4-CNB exposure occurred in rats or mice. In both studies, the mean body weight gains of exposed animals were similar to those of the respective controls. In rats, inhalation exposure to 2- or 4-CNB resulted in methemoglobinemia leading to a regenerative anemia and a variety of tissue changes secondary to the oxidative erythrocyte injury. In the 2-CNB study, methemoglobinemia resulted in a normocytic, normochromic, responsive anemia, whereas with 4-CNB, the methemoglobinemia was more severe and resulted in a macrocytic, hyperchromic, responsive anemia. Alterations of erythrocyte morphology were observed in both studies; changes included Heinz bodies, poikilocytes, and polychromasia. In rats, both isomers caused increases in serum activities of alanine aminotransferase and sorbitol dehydrogenase and increased bile acid concentrations. Microscopic liver changes included hemosiderin deposition in Kupffer cells (rats and mice exposed to 4-CNB), hepatocytomegaly (mice), and cytoplasmic basophilia (rats). Hepatocellular necrosis and chronic inflammation observed in mice were rather specific to the 2-CNB isomer, as only slight evidence of focal necrosis in the liver was observed in mice exposed to 4-CNB. Splenic lesions included hemosiderin accumulation, capsular fibrosis, and increased hematopoietic cell proliferation. Increased bone marrow hemosiderin and hematopoietic cell proliferation and kidney tubule hemosiderin deposition were also observed. Other findings, attributed to chemical exposure but not to the hematotoxicity, were described. Lesions included hyaline droplet nephropathy and degeneration of the testis in male rats exposed to 4-CNB, inflammation of the harderian gland in rats exposed to 4-CNB, hyperplasia of the nasal cavity epithelium in rats exposed to 2-CNB, and hyperplasia of the forestomach epithelium in mice exposed to 4-CNB; these lesions have not been described previously in studies with these chemicals. Based on the exposure concentrations evaluated, A no-observed-adverse-effect level (NOAEL) for histopathological injury in mice was 4.5 ppm for 2-chloronitrobenzene and 6 ppm for 4-chloronitrobenzene; a NOAEL was not determined for rats.