Hepatic deficiency in transcriptional cofactor TBL1 promotes liver steatosis and hypertriglyceridemia.

The aberrant accumulation of lipids in the liver ("fatty liver") is tightly associated with several components of the metabolic syndrome, including type 2 diabetes, coronary heart disease, and atherosclerosis. Here we show that the impaired hepatic expression of transcriptional cofactor transducin beta-like (TBL) 1 represents a common feature of mono- and multigenic fatty liver mouse models. Indeed, the liver-specific ablation of TBL1 gene expression in healthy mice promoted hypertriglyceridemia and hepatic steatosis under both normal and high-fat dietary conditions. TBL1 deficiency resulted in inhibition of fatty acid oxidation due to impaired functional cooperation with its heterodimerization partner TBL-related (TBLR) 1 and the nuclear receptor peroxisome proliferator-activated receptor (PPAR) α. As TBL1 expression levels were found to also inversely correlate with liver fat content in human patients, the lack of hepatic TBL1/TBLR1 cofactor activity may represent a molecular rationale for hepatic steatosis in subjects with obesity and the metabolic syndrome.

Radioimmunotherapy of colorectal cancer liver metastases: combination with radiotherapy.

The expected therapeutic gain of a combined radioimmunotherapy (RIT) with conventional radiotherapy (RT) would be a synergy of tumor irradiation, provided that toxic, dose-limiting side effects concern different organs. We have shown in a model of subcutaneous human colon cancer transplants in nude mice that RIT with 131I-labeled anti-CEA antibody fragments combined with fractionated RT give an additive therapeutic effect without increase of side effects. A second study of different timing schedules of RIT and RT has shown that close association of both therapies without delay is more efficient than a therapy with a treatment-free interval of two weeks. In a new model of human colon cancer liver metastases in nude mice, early treatment with RIT and with RT has been curative, whereas therapies initiated later were less efficient, suggesting that the combined therapy is likely to be more efficient in an adjuvant situation after surgery. At the clinical level, six patients with limited liver metastatic disease from colorectal cancer were treated with RIT using 200 mCi 131I-labeled anti-CEA MAb F(ab')2 fragments combined with fractionated external beam RT of 20 Gy to the entire liver. As expected, spontaneously reversible bone marrow toxicity grade 3 to 4 and reversible liver toxicity grade 1 to 3 have been observed. By computerized tomography, three patients showed stable disease and one patient partial remission, whereas two patients had progressive disease. In conclusion, animal experiments have shown a clear advantage of combined RT and RIT, and the clinical study shows the feasibility of such a therapy in patients with colorectal cancer liver metastases.

Perampanel: a significant liver enzyme inducer in some patients?

Perampanel is one of the latest released antiepileptic drugs (AEDs). Early studies suggest no significant liver enzyme induction from this compound. We report on two patients with medically resistant epilepsy, who had perampanel added to their usual regimen. Both experienced a worsening of their epilepsy and presented in convulsive status epilepticus; concurrent antiepileptic drug levels (phenytoin, phenobarbital, rufinamide) were significantly decreased (<50%) in comparison with levels prior to perampanel introduction. Intravenous load and significant increase of maintenance dosages were needed to restore therapeutic drug levels. In one patient, further increase of perampanel resulted in a new drop of phenytoin level. This suggests that perampanel could, in some subjects, induce liver enzymes and interact with concomitant AEDs; monitoring levels of concomitant compounds could be useful.

Liver enzyme elevation after lamivudine withdrawal in HIV-hepatitis B virus co-infected patients: the Swiss HIV Cohort Study.

Background The principal causes of liver enzyme elevation among HIV-hepatitis B virus (HBV) co-infected patients are the hepatotoxic effects of antiretroviral therapy (ART), alcohol abuse, ART-induced immune reconstitution and the exacerbation of chronic HBV infection. Objectives To investigate the incidence and severity of liver enzyme elevation, liver failure and death following lamivudine (3TC) withdrawal in HIV-HBV co-infected patients. Methods Retrospective analysis of the Swiss HIV Cohort Study database to assess the clinical and biological consequences of the discontinuation of 3TC. Variables considered for analysis included liver enzyme, HIV virological and immunological parameters, and medication prescribed during a 6-month period following 3TC withdrawal. Results 3TC was discontinued in 255 patients on 363 occasions. On 147 occasions (109 patients), a follow-up visit within 6 months following 3TC withdrawal was recorded. Among these patients, liver enzyme elevation occurred on 42 occasions (29%), three of them (2%) with severity grade III and five of them (3.4%) with severity grade IV elevations (as defined by the AIDS Clinical Trials Group). Three patients presented with fulminant hepatitis. One death (0.7%) was recorded. Conclusions HBV reactivation leading to liver dysfunction may be an under-reported consequence of 3TC withdrawal in HIV-HBV co-infected patients. Regular monitoring of HBV markers is warranted if active therapy against HBV is discontinued.

Should possible recurrence of disease contraindicate liver transplantation in patients with end-stage alveolar echinococcosis? A 20-year follow-up study.

Liver transplantation (LT) is currently contraindicated in patients with residual or metastatic alveolar echinococcosis (AE) lesions. We evaluated the long-term course of such patients who underwent LT and were subsequently treated with benzimidazoles. Clinical, imaging, serological, and therapeutic data were collected from 5 patients with residual/recurrent AE lesions who survived for more than 15 years. Since 2004, [(18) F]-2-fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET) images were available, and the levels of serum antibodies (Abs) against Echinococcus multilocularis-recombinant antigens were evaluated. Median survival time after LT was 21 years. These patients were from a prospective cohort of 23 patients with AE who underwent LT: 5 of 8 patients with residual/recurrent AE and 4 of 9 patients without residual/recurrent AE were alive in September 2009. High doses of immunosuppressive drugs, the late introduction of therapy with benzimidazoles, its withdrawal due to side effects, and nonadherence to this therapy adversely affected the prognosis. Anti-Em2(plus) and anti-rEm18 Ab levels and standard FDG-PET enabled the efficacy of therapy on the growth of EA lesions to be assessed. However, meaningful variations in Ab levels were observed below diagnostic cutoff values; and in monitoring AE lesions, images of FDG uptake taken 3 hours after its injection were more sensitive than images obtained 1 hour after its injection. In conclusion, benzimidazoles can control residual/recurrent AE lesions after LT. Using anti-rEm18 or anti-Em2(plus) Ab levels and the delayed acquisition of FDG-PET images can improve the functional assessment of disease activity. The potential recurrence of disease, especially in patients with residual or metastatic AE lesions, should not be regarded as a contraindication to LT when AE is considered to be lethal in the short term.

Liver segmentation: Practical tips.

The liver segmentation system, described by Couinaud, is based on the identification of the three hepatic veins and the plane passing by the portal vein bifurcation. Nowadays, Couinaud's description is the most widely used classification since it is better suited for surgery and more accurate for the localisation and monitoring of intra-parenchymal lesions. Knowledge of the anatomy of the portal and venous system is therefore essential, as is knowledge of the variants resulting from changes occurring during the embryological development of the vitelline and umbilical veins. In this paper, the authors propose a straightforward systematisation of the liver in six steps using several additional anatomical points of reference. These points of reference are simple and quickly identifiable in any radiological examination with section imaging, in order to avoid any mistakes in daily practice. In fact, accurate description impacts on many diagnostic and therapeutic applications in interventional radiology and surgery. This description will allow better preparation for biopsy, portal vein embolisation, transjugular intrahepatic portosystemic shunt, tumour resection or partial hepatectomy for transplantation. Such advance planning will reduce intra- and postoperative difficulties and complications.

Differentiation of focal liver lesions: usefulness of parametric imaging with contrast-enhanced US.

Purpose: To evaluate whether parametric imaging with contrast material-enhanced ultrasonography (US) is superior to visual assessment for the differential diagnosis of focal liver lesions (FLLs). Materials and Methods: This study had institutional review board approval, and verbal patient informed consent was obtained. Between August 2005 and October 2008, 146 FLLs in 145 patients (63 women, 82 men; mean age, 62.5 years; age range, 22-89 years) were imaged with real-time low-mechanical-index contrast-enhanced US after a bolus injection of 2.4 mL of a second-generation contrast agent. Clips showing contrast agent uptake kinetics (including arterial, portal, and late phases) were recorded and subsequently analyzed off-line with dedicated image processing software. Analysis of the dynamic vascular patterns (DVPs) of lesions with respect to adjacent parenchyma allowed mapping DVP signatures on a single parametric image. Cine loops of contrast-enhanced US and results from parametric imaging of DVP were assessed separately by three independent off-site readers who classified each lesion as benign, malignant, or indeterminate. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated for both techniques. Interobserver agreement (κ statistics) was determined. Results: Sensitivities for visual interpretation of cine loops for the three readers were 85.0%, 77.9%, and 87.6%, which improved significantly to 96.5%, 97.3%, and 96.5% for parametric imaging, respectively (P < .05, McNemar test), while retaining high specificity (90.9% for all three readers). Accuracy scores of parametric imaging were higher than those of conventional contrast-enhanced US for all three readers (P < .001, McNemar test). Interobserver agreement increased with DVP parametric imaging compared with conventional contrast-enhanced US (change of κ from 0.54 to 0.99). Conclusion: Parametric imaging of DVP improves diagnostic performance of contrast-enhanced US in the differentiation between malignant and benign FLLs; it also provides excellent interobserver agreement.

Long-term expansion of transplantable human fetal liver hematopoietic stem cells

Hematopoietic stem cells (HSCs), with their dual ability for self-renewal and multilineage differentiation, constitute an essential component of hematopoietic transplantations. Human fetal liver (FL) represents a promising alternative HSC source, and we previously reported simple culture conditions allowing long-term expansion of FL hematopoietic progenitors. In the present study, we used the nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mouse xenotransplantation assay to confirm that human FL is rich in NOD/SCID-repopulating cells (SRCs) and to show that these culture conditions repeatedly maintained short- and long-term SRCs from various FL samples for at least 28 days. Quantitative limited dilution analysis in NOD/SCID mice demonstrated for the first time that a 10- to over a 100-fold net expansion of FL SRCs could be achieved after 28 days of culture. The efficiency of this culture system may lead to an increase in the use of FL as a source of HSCs for transplantation in adult patients, as previously demonstrated with umbilical cord blood under different culture conditions.

Parametric imaging for characterizing focal liver lesions in contrast-enhanced ultrasound.

The differentiation between benign and malignant focal liver lesions plays an important role in diagnosis of liver disease and therapeutic planning of local or general disease. This differentiation, based on characterization, relies on the observation of the dynamic vascular patterns (DVP) of lesions with respect to adjacent parenchyma, and may be assessed during contrast-enhanced ultrasound imaging after a bolus injection. For instance, hemangiomas (i.e., benign lesions) exhibit hyper-enhanced signatures over time, whereas metastases (i.e., malignant lesions) frequently present hyperenhanced foci during the arterial phase and always become hypo-enhanced afterwards. The objective of this work was to develop a new parametric imaging technique, aimed at mapping the DVP signatures into a single image called a DVP parametric image, conceived as a diagnostic aid tool for characterizing lesion types. The methodology consisted in processing a time sequence of images (DICOM video data) using four consecutive steps: (1) pre-processing combining image motion correction and linearization to derive an echo-power signal, in each pixel, proportional to local contrast agent concentration over time; (2) signal modeling, by means of a curve-fitting optimization, to compute a difference signal in each pixel, as the subtraction of adjacent parenchyma kinetic from the echopower signal; (3) classification of difference signals; and (4) parametric image rendering to represent classified pixels as a support for diagnosis. DVP parametric imaging was the object of a clinical assessment on a total of 146 lesions, imaged using different medical ultrasound systems. The resulting sensitivity and specificity were 97% and 91%, respectively, which compare favorably with scores of 81 to 95% and 80 to 95% reported in medical literature for sensitivity and specificity, respectively.

Glucose transporters in the regulation of intestinal, renal, and liver glucose fluxes.

Five functional mammalian facilitated hexose carriers (GLUTs) have been characterized by molecular cloning. By functional expression in heterologous systems, their specificity and affinity for different hexoses have been defined. There are three high-affinity transporters (GLUT-1, GLUT-3 and GLUT-4) and one low-affinity transporter (GLUT-2), and GLUT-5 is primarily a fructose carrier. Because their Michaelis constants (Km) are below the normal blood glucose concentration, the high-affinity transporters function at rates close to maximal velocity. Thus their level of cell surface expression greatly influences the rate of glucose uptake into the cells. In contrast, the rate of glucose uptake by GLUT-2 (Km = 17 mM) increases in parallel with the rise in blood glucose over the physiological concentration range. High-affinity transporters are found in almost every tissue, but their expression is higher in cells with high glycolytic activity. Glut-2, however, is found in tissues carrying large glucose fluxes, such as intestine, kidney, and liver. As an adaptive response to variations in metabolic conditions, the expression of these transporters is regulated by glucose and different hormones. Thus, because of their specific characteristics and regulated expression, the facilitated glucose transporters control fundamental aspects of glucose homeostasis. I review data pertaining to the structure and regulated expression of the glucose carriers present in intestine, kidney, and liver and discuss their role in the control of glucose flux into or out of these different tissues.

A liver protein fraction regulating hormone-dependent in vitro transcription from the vitellogenin genes induces their expression in Xenopus oocytes.

Xenopus laevis oocytes were used to assay for trans-acting factors shown previously to be involved in the liver-specific regulation of the vitellogenin genes in vitro. To this end, crude liver nuclear extracts obtained from adult estrogen-induced Xenopus females were fractionated by heparin-Sepharose chromatography using successive elutions with 0.1, 0.35, 0.6, and 1.0 M KCl. When these four fractions were injected into oocytes, only the 0.6-M KCl protein fraction significantly stimulated mRNA synthesis from the endogenous B class vitellogenin genes. This same fraction induced estrogen-dependent in vitro transcription from the vitellogenin B1 promoter, suggesting that it contains at least a minimal set of basal transcription factors as well as two positive factors essential for vitellogenin in vitro transcription, i.e. the NF-I-like liver factor B and the estrogen receptor (ER). The presence of these two latter factors was determined by footprinting and gel retardation assays, respectively. In contrast, injection of an expression vector carrying the sequence encoding the ER was unable to activate transcription from the oocyte chromosomal vitellogenin genes. This suggests that the ER alone cannot overcome tissue-specific barriers and that one or several additional liver components participate in mediating tissue-specific expression of the vitellogenin genes. In this respect, we present evidence that the oocyte germinal vesicles contain an NF-I-like activity different from that found in hepatocytes of adult frogs. This observation might explain the lack of vitellogenin gene activation in oocytes injected with the ER cDNA only.

Reduced IFNλ4 activity is associated with improved HCV clearance and reduced expression of interferon-stimulated genes

Hepatitis C virus (HCV) infections are the major cause of chronic liver disease, cirrhosis and hepatocellular carcinoma worldwide. Both spontaneous and treatment-induced clearance of HCV depend on genetic variation within the interferon-lambda locus, but until now no clear causal relationship has been established. Here we demonstrate that an amino-acid substitution in the IFNλ4 protein changing a proline at position 70 to a serine (P70S) substantially alters its antiviral activity. Patients harbouring the impaired IFNλ4-S70 variant display lower interferon-stimulated gene (ISG) expression levels, better treatment response rates and better spontaneous clearance rates, compared with patients coding for the fully active IFNλ4-P70 variant. Altogether, these data provide evidence supporting a role for the active IFNλ4 protein as the driver of high hepatic ISG expression as well as the cause of poor HCV clearance.

Transcript profiling suggests that differential metabolic adaptation of mice to a high fat diet is associated with changes in liver to muscle lipid fluxes.

Genetically homogenous C57Bl/6 mice display differential metabolic adaptation when fed a high fat diet for 9 months. Most become obese and diabetic, but a significant fraction remains lean and diabetic or lean and non-diabetic. Here, we performed microarray analysis of "metabolic" transcripts expressed in liver and hindlimb muscles to evaluate: (i) whether expressed transcript patterns could indicate changes in metabolic pathways associated with the different phenotypes, (ii) how these changes differed from the early metabolic adaptation to short term high fat feeding, and (iii) whether gene classifiers could be established that were characteristic of each metabolic phenotype. Our data indicate that obesity/diabetes was associated with preserved hepatic lipogenic gene expression and increased plasma levels of very low density lipoprotein and, in muscle, with an increase in lipoprotein lipase gene expression. This suggests increased muscle fatty acid uptake, which may favor insulin resistance. In contrast, the lean mice showed a strong reduction in the expression of hepatic lipogenic genes, in particular of Scd-1, a gene linked to sensitivity to diet-induced obesity; the lean and non-diabetic mice presented an additional increased expression of eNos in liver. After 1 week of high fat feeding the liver gene expression pattern was distinct from that seen at 9 months in any of the three mouse groups, thus indicating progressive establishment of the different phenotypes. Strikingly, development of the obese phenotype involved re-expression of Scd-1 and other lipogenic genes. Finally, gene classifiers could be established that were characteristic of each metabolic phenotype. Together, these data suggest that epigenetic mechanisms influence gene expression patterns and metabolic fates.