Hepatic bile acid transport increases in the postprandial state: A functional 11C-CSar PET/CT study in healthy humans.

BACKGROUND & AIMS: It is not known how hepatic bile acids transport kinetics changes postprandially in the intact liver. We used positron emission tomography (PET)/computed tomography (CT) with the tracer [N-methyl-11C]cholylsarcosine (11C-CSar), a synthetic sarcosine conjugate of cholic acid, to quantify fasting and postprandial hepatic bile acid transport kinetics in healthy human participants. METHODS: Six healthy human participants underwent dynamic liver 11C-CSar PET/CT (60 min) during fasting and from 15 min after ingestion of a standard liquid meal. Hepatobiliary secretion kinetics of 11C-CSar was calculated from PET data, blood samples (arterial and hepatic venous) and hepatic blood flow measured using indocyanine green infusion. RESULTS: In the postprandial state, hepatic blood perfusion increased on average by 30% (p <0.01), and the flow-independent hepatic intrinsic clearance of 11C-CSar from blood into bile increased by 17% from 1.82 (range, 1.59-2.05) to 2.13 (range, 1.75-2.50) ml blood/min/ml liver tissue (p = 0.042). The increased intrinsic clearance of 11C-CSar was not caused by changes in the basolateral clearance efficacy of 11C-CSar but rather by an upregulated apical transport, as shown by an increase in the rate constant for apical secretion of 11C-CSar from hepatocyte to bile from 0.40 (0.25-0.54) min-1 to 0.67 (0.36-0.98) min-1 (p = 0.03). This resulted in a 33% increase in the intrahepatic bile flow (p = 0.03). CONCLUSIONS: The rate constant for the transport of bile acids from hepatocytes into biliary canaliculi and the bile flow increased significantly in the postprandial state. This reduced the mean 11C-CSar residence time in the hepatocytes. LAY SUMMARY: Bile acids are important for digestion of dietary lipids including vitamins. We examined how the secretion of bile acids by the liver into the intestines changes after a standard liquid meal. The transport of bile acids from liver cells into bile and bile flow was increased after the meal.

Divergences in Macrophage Activation Markers Soluble CD163 and Mannose Receptor in Patients With Non-cirrhotic and Cirrhotic Portal Hypertension.

INTRODUCTION: Macrophages are involved in development and progression of chronic liver disease and portal hypertension. The macrophage activation markers soluble (s)CD163 and soluble mannose receptor (sMR), are associated with portal hypertension in patient with liver cirrhosis but never investigated in patients with non-cirrhotic portal hypertension. We hypothesized higher levels in cirrhotic patients with portal hypertension than patients with non-cirrhotic portal hypertension. We investigated sCD163 and sMR levels in patients with portal hypertension due to idiopathic portal hypertension (IPH) and portal vein thrombosis (PVT) in patients with and without cirrhosis. METHODS: We studied plasma sCD163 and sMR levels in patients with IPH (n = 26), non-cirrhotic PVT (n = 20), patients with cirrhosis without PVT (n = 31) and with PVT (n = 17), and healthy controls (n = 15). RESULTS: Median sCD163 concentration was 1.51 (95% CI: 1.24-1.83) mg/L in healthy controls, 1.96 (95% CI: 1.49-2.56) in patients with non-cirrhotic PVT and 2.16 (95% CI: 1.75-2.66) in patients with IPH. There was no difference between non-cirrhotic PVT patients and healthy controls, whereas IPH patients had significantly higher levels than controls (P < 0.05). The median sCD163 was significantly higher in the cirrhotic groups compared to the other groups, with a median sCD163 of 6.31 (95% CI: 5.16-7.73) in cirrhotics without PVT and 5.19 (95% CI: 4.18-6.46) with PVT (P < 0.01, all). Similar differences were observed for sMR. CONCLUSION: Soluble CD163 and sMR levels are elevated in patients with IPH and patients with cirrhosis, but normal in patients with non-cirrhotic PVT. This suggests that hepatic macrophage activation is more driven by the underlying liver disease with cirrhosis than portal hypertension.

[Workup of dysphagia in Denmark].

This review is about dysphagia, which is a collective term for all types of difficulty in swallowing. The causes behind are numerous, and the symptoms can be divided into oropharyngeal and oesophageal dysphagia. In the elderly population, the symptoms result in a thorough investigation, as it may be the first sign of underlying malignant disease. If malignant disease is not confirmed, the patient may be referred to the initial doctor. It is therefore important to know, that there is a large range of aetiologies and investigative possibilities of non-malignant dysphagia.

Unexplained cholestasis in adults and adolescents: diagnostic benefit of genetic examination.

OBJECTIVES: A few adult and adolescent patients with even severe cholestatic liver disease remain unexplained after standard diagnostic work-up. We studied the value of genetic examination in such patients and developed a panel of eight genes with known cholestatic associations. MATERIALS AND METHODS: Thirty-three patients with unexplained cholestasis despite a thorough clinical work-up were examined for sequence variations in the coding regions of the ABCB4, ABCB11, ABCC2, ABCG5, ATP8B1, JAG1, NOTCH2, and UGT1A1 genes and the promoter region of UGT1A1 by massive parallel sequencing of DNA extracted from whole blood. Hepatologists and clinical geneticists evaluated the causal potential of genetic variants. RESULTS: In 9/33 patients (27%), we identified genetic variants as a certain causal factor and in further 9/33 (27%) variants as a possible contributing factor. In most cases, a detailed family history was necessary to establish the importance of genetic variants. Genetic causes were identified in 6/13 women (46%) with intrahepatic cholestasis during pregnancy and persisting abnormal biochemistry after delivery. CONCLUSIONS: Our study suggests that a small number of well-known genetic variants are involved in at least 27-54% of patients with unexplained cholestasis. An expanded panel will likely explain more cases. This motivates genetic testing of these patients. Genetic testing, however, cannot stand alone but should be combined with a clinical genetic work-up in collaboration between hepatologists and clinical geneticists.

Functional assessment of hepatobiliary secretion by 11C-cholylsarcosine positron emission tomography.

Positron emission tomography (PET) with 11C-cholylsarcosine (11C-CSar), a radiolabelled synthetic N-methylglycine (sarcosine) conjugate of cholic acid, is a novel molecular imaging technique that enables quantitative assessment of the individual transport steps involved in hepatic secretion of conjugated bile acids. Here, we present the method and discuss its potential clinical and scientific applications based on findings in the first human study of healthy subjects and patients with cholestasis. We also present a clinical example of a patient studied during and six months after an episode of drug-induced cholestatic liver injury.

Time course of compromised urea synthesis in patients with alcoholic hepatitis.

OBJECTIVES: Alcoholic hepatitis (AH) markedly decreases the urea synthesis capacity. We aimed to investigate the time course of this compromised essential liver function in patients with AH and its relation to treatment and survival. MATERIALS AND METHODS: Thirty patients with AH were included in a prospective cohort study. We measured the substrate-independent urea synthesis capacity, i.e., the functional hepatic nitrogen clearance (FHNC), in the patients at study entry and again at three months (survivors/available: n = 17). Patients with severe disease (Glasgow Alcoholic Hepatitis Score ≥9, n = 17) were randomized to receive either prednisolone or pentoxifylline and were in addition examined after 14 days (n = 9). RESULTS: FHNC (normal range = 25-45 L/h) was markedly decreased at study entry (median = 5.6 (IQR = 3.0-9.6) L/h) and increased by three-fold in survivors at three months (15.1 (12.0-22.9) L/h; p < .001). In patients with severe AH, FHNC was also increased after 14 days of pharmacologic treatment and showed the greatest increase in the patients taking prednisolone (prednisolone 25.4 (20.6-26.2) L/h vs. pentoxifylline 12.3 (8.0-15.3) L/h; p = .05). FHNC at study entry was lower in 90-day non-survivors than in survivors (p = .04). CONCLUSIONS: The decrease in the urea synthesis capacity in patients with AH was the most marked in short-term non-survivors and partly recovered in survivors at three months. In patients on pharmacologic treatment, recovery was observed already after 14 days, and it was nearly complete in those on prednisolone. Thus, metabolic liver failure in AH seems to be prognostically important, is potentially reversible, and may recover more rapidly following treatment with prednisolone.

[Acute-on-chronic liver failure].

Acute-on-chronic liver failure (ACLF) is a clinical syndrome characterized by acute decompensation of liver cirrhosis, organ failure and high short-term mortality (20-80% at one month). The main precipitants are infections and excessive alcohol intake, and the mechanistic features include a high level of systemic inflammation, macrophage activation and liver injury. The severity of ACLF is graded according to the number and extent of organ failures. Prognostic scores help predict mortality and support decisions on intensive treatment or futility.

Hepatobiliary transport kinetics of the conjugated bile acid tracer 11C-CSar quantified in healthy humans and patients by positron emission tomography.

BACKGROUND & AIMS: Hepatobiliary secretion of bile acids is an important liver function. Here, we quantified the hepatic transport kinetics of conjugated bile acids using the bile acid tracer [N-methyl-11C]cholylsarcosine (11C-CSar) and positron emission tomography (PET). METHODS: Nine healthy participants and eight patients with varying degrees of cholestasis were examined with 11C-CSar PET and measurement of arterial and hepatic venous blood concentrations of 11C-CSar. RESULTS: Results are presented as median (range). The hepatic intrinsic clearance was 1.50 (1.20-1.76) ml blood/min/ml liver tissue in healthy participants and 0.46 (0.13-0.91) in patients. In healthy participants, the rate constant for secretion of 11C-CSar from hepatocytes to bile was 0.36 (0.30-0.62)min-1, 20 times higher than the rate constant for backflux from hepatocytes to blood (0.02, 0.005-0.07min-1). In the patients, rate constant for transport from hepatocyte to bile was reduced to 0.12 (0.006-0.27)min-1, 2.3times higher than the rate constant for backflux to blood (0.05, 0.04-0.09). The increased backflux did not fully normalize exposure of the hepatocyte to bile acids as mean hepatocyte residence time of 11C-CSar was 2.5 (1.6-3.1)min in healthy participants and 6.4 (3.1-23.7)min in patients. The rate constant for transport of 11C-CSar from intrahepatic to extrahepatic bile was 0.057 (0.023-0.11)min-1 in healthy participants and only slightly reduced in patients 0.039 (0.017-0.066). CONCLUSIONS: This first in vivo quantification of individual steps involved in the hepatobiliary secretion of a conjugated bile acid in humans provided new insight into cholestatic disease. LAY SUMMARY: Positron emission tomography (PET) using the radiolabelled bile acid (11C-CSar) enabled quantification of the individual steps of the hepatic transport of bile acids from blood to bile in man. Cholestasis reduced uptake and secretion and increased backflux to blood. These findings improve our understanding of cholestatic liver diseases and may support therapeutic decisions. CLINICAL TRIAL REGISTRATION NUMBER: The trial is registered at ClinicalTrials.gov (NCT01879735).

Alcoholic Hepatitis Markedly Decreases the Capacity for Urea Synthesis.

BACKGROUND AND AIM: Data on quantitative metabolic liver functions in the life-threatening disease alcoholic hepatitis are scarce. Urea synthesis is an essential metabolic liver function that plays a key regulatory role in nitrogen homeostasis. The urea synthesis capacity decreases in patients with compromised liver function, whereas it increases in patients with inflammation. Alcoholic hepatitis involves both mechanisms, but how these opposite effects are balanced remains unclear. Our aim was to investigate how alcoholic hepatitis affects the capacity for urea synthesis. We related these findings to another measure of metabolic liver function, the galactose elimination capacity (GEC), as well as to clinical disease severity. METHODS: We included 20 patients with alcoholic hepatitis and 7 healthy controls. The urea synthesis capacity was quantified by the functional hepatic nitrogen clearance (FHNC), i.e., the slope of the linear relationship between the blood α-amino nitrogen concentration and urea nitrogen synthesis rate during alanine infusion. The GEC was determined using blood concentration decay curves after intravenous bolus injection of galactose. Clinical disease severity was assessed by the Glasgow Alcoholic Hepatitis Score and Model for End-Stage Liver Disease (MELD) score. RESULTS: The FHNC was markedly decreased in the alcoholic hepatitis patients compared with the healthy controls (7.2±4.9 L/h vs. 37.4±6.8 L/h, P<0.01), and the largest decrease was observed in those with severe alcoholic hepatitis (4.9±3.6 L/h vs. 9.9±4.9 L/h, P<0.05). The GEC was less markedly reduced than the FHNC. A negative correlation was detected between the FHNC and MELD score (rho = -0.49, P<0.05). CONCLUSIONS: Alcoholic hepatitis markedly decreases the urea synthesis capacity. This decrease is associated with an increase in clinical disease severity. Thus, the metabolic failure in alcoholic hepatitis prevails such that the liver cannot adequately perform the metabolic up-regulation observed in other stressful states, including extrahepatic inflammation, which may contribute to the patients' poor prognosis.

Hepatobiliary Secretion Kinetics of Conjugated Bile Acids Measured in Pigs by 11C-Cholylsarcosine PET.

UNLABELLED: The aim of this study was to develop a method for the quantification of hepatobiliary uptake and secretion of conjugated bile acids with PET and the (11)C-labeled conjugated bile acid analog [N-methyl-(11)C]cholylsarcosine ((11)C-CSar). METHODS: Six pigs (13 experiments) underwent dynamic (11)C-CSar PET of the liver with simultaneous measurements of hepatic blood perfusion and (11)C-CSar concentrations in arterial, portal, and hepatic venous blood. In 3 pigs (7 experiments), bile was collected from a catheter in the common hepatic duct. PET data were analyzed with a 2-tissue compartmental model with calculation of rate constants for the transport of (11)C-CSar among blood, hepatocytes, and intra- and extrahepatic bile ducts. PET results were validated against invasive blood and bile measurements. RESULTS: The directly measured rate of secretion of (11)C-CSar into bile was equal to the rate of removal from blood at steady state. Accordingly, hepatocytes did not accumulate bile acids but simply facilitated the transport of bile acids from blood to bile against a measured concentration gradient of 4,000. The rate constant for the secretion of (11)C-CSar from hepatocytes into bile in experiments with a catheter in the common hepatic duct was 25% of that in experiments without a catheter (P < 0.05); we interpreted this result to be mild cholestasis caused by the catheter. The catheter caused an increased backflux of (11)C-CSar from hepatocytes to blood, and hepatic blood flow was 25% higher than in experiments without the catheter. The capacity for the overall transport of (11)C-CSar from blood to bile, as quantified by intrinsic clearance, was significantly lower in experiments with the catheter than in those without the catheter (P < 0.001). PET and blood measurements correlated significantly (P < 0.05). CONCLUSION: The in vivo kinetics of hepatobiliary secretion of conjugated bile acids can now be determined by dynamic (11)C-CSar PET.

Short-term and long-term causes of death in patients with alcoholic hepatitis in Denmark.

BACKGROUND & AIMS: The incidence of acute alcoholic hepatitis is increasing, and mortality is high. However, causes of death among patients with alcoholic hepatitis have not been systematically recorded. We investigated causes of death in a population-based cohort of patients with alcoholic hepatitis who were followed for as long as 10 years. METHODS: We used the Danish National Registry of Patients to identify all patients with a first-time episode of alcoholic hepatitis from 1999 through 2008. We collected and analyzed data on 1951 patients, identifying causes of death, diagnoses of cirrhosis, and alcohol abuse. RESULTS: Of the 1951 patients, 401 died within the first 84 days after admission, and 600 died later (through December 31, 2008). Most deaths within the first 84 days after admission resulted from liver failure (40%), infections (20%), or hepatorenal syndrome (11%). Beyond 84 days, causes of deaths differed between patients with and without cirrhosis; most patients without cirrhosis (n = 326) died of causes related to alcohol abuse, whereas most patients with cirrhosis (n = 675) died of liver failure (34%), infections (16%), or variceal bleeding (11%). Cirrhosis was present in 51% of patients diagnosed with alcoholic hepatitis. Among patients without cirrhosis, 24% developed cirrhosis within 10 years; continued alcohol abuse was a strong risk factor for cirrhosis (hazard ratio, 2.14; 95% confidence interval, 1.50-3.05). The 10-year risk of a second episode of alcoholic hepatitis was 12%. CONCLUSIONS: On the basis of a study of the Danish population, the most common causes of death among patients with alcoholic hepatitis, within 84 days and within 10 years, are liver-related events and infections. Strategies are to identify and treat these complications and to reduce alcoholism.

Leukocyte transcript alterations in West-African girls following a booster vaccination with diphtheria-tetanus-pertussis vaccine.

BACKGROUND: Observational studies from low-income countries have shown that the vaccination against diphtheria, tetanus and pertussis (DTP) is associated with excess female mortality due to infectious diseases. METHODS: To investigate possible changes in gene expression after DTP vaccination, we identified a group of nine comparable West African girls, from a biobank of 356 children, who were due to receive DTP booster vaccine at age 18 months. As a pilot experiment we extracted RNA from blood samples before, and 6 weeks after, vaccination to analyze the coding transcriptome in leukocytes using expression microarrays, and ended up with information from eight girls. The data was further analyzed using dedicated array pathway and network software. We aimed to study whether DTP vaccination introduced a systematic alteration in the immune system in girls. RESULTS: We found very few transcripts to alter systematically. Those that did mainly belonged to the Interferon (IFN) signalling pathway. We scrutinized this pathway as well as the Interleukin (IL) pathways. Two out of eight showed a down-regulated IFN pathway and two showed an up-regulated IFN pathway. The two with down-regulated IFN pathway had also down-regulated IL-6 pathway. In the study of networks, two of the girls stood out as not having the inflammatory response as top altered network. CONCLUSION: The transcriptome changes following DTP booster vaccination were subtle, but although the material was small, it was possible to identify sub groups that deviate from each other, mainly in the IFN response.