bluuebunny/crossref_metadata_2025 huggingface dataset:
Frontoparietal cortical activity of methamphetamine‐dependent and comparison subjects performing a delay discounting task
Authors: Monterosso John R. , Ainslie George , Xu Jiansong , Cordova Xochitl , Domier Catherine P. , London Edythe D.
Published: August 2006

Relative to individuals who do not have addictive disorders, drug abusers exhibit greater devaluation of rewards as a function of their delay (“delay discounting”). The present study sought to extend this finding to methamphetamine (MA) abusers and to help understand its neural basis. MA abusers (n = 12) and control subjects who did not use illicit drugs (n = 17) participated in tests of delay discounting with hypothetical money rewards. We then used a derived estimate of each individual's delay discounting to generate a functional magnetic resonance imaging probe task consisting of three conditions: “hard choices,” requiring selections between “smaller, sooner” and “larger, later” alternatives that were similarly valued given the individual's delay discounting; “easy choices,” in which alternatives differed dramatically in value; and a “no choice” control condition. MA abusers exhibited more delay discounting than control subjects (P < 0.05). Across groups, the “hard choice > no choice” contrast revealed significant effects in the ventrolateral prefrontal cortex, dorsolateral prefrontal cortex (DLPFC), dorsal anterior cingulate cortex, and areas surrounding the intraparietal sulcus (IPS). With group comparisons limited to these clusters, the “hard choice > easy choice” contrast indicated significant group differences in task‐related activity within the left DLPFC and right IPS; qualitatively similar nonsignificant effects were present in the other clusters tested. Whereas control subjects showed less recruitment associated with easy than with hard choices, MA abusers generally did not. Correlational analysis did not indicate a relationship between this anomaly in frontoparietal recruitment and greater degree of delay discounting exhibited by MA abusers. Therefore, while apparent inefficiency of cortical processing related to decision‐making in MA abusers may contribute to the neural basis of enhanced delay discounting by this population, other factors remain to be identified. Hum. Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Spatiotemporal cortical dynamics underlying abstract and concrete word reading
Authors: Dhond Rupali P. , Witzel Thomas , Dale Anders M. , Halgren Eric
Published: August 2006

The current study used whole‐head anatomically constrained magnetoencephalography (aMEG) to spatiotemporally map brain responses while subjects made abstract/concrete judgments on visually presented words. Both word types evoked a similar posterior‐to‐anterior sequence of cortical recruitment involving occipital, temporal, parietal, and frontal areas from ∼ 100 to 900 ms poststimulus. A prominent left temporofrontal N400m was smaller to abstract words, while the right temporal N400m was smaller to concrete words, suggesting that differences may exist in their semantic representation. The left temporofrontal decrease for abstract words is consistent with EEG studies, indicating a smaller N400 for abstract words based on a more extensive or accessible lexicosemantic network. Furthermore, the N400m peaked at ∼420 ms and was followed by a large right hemisphere medial occipitoparietal as well as lateral parietal response to concrete words peaking at ∼550 ms, perhaps embodying imagistic processing. These data suggest that words may be initially understood using a left‐lateralized (frontotemporal) verbal‐linguistic system that for concrete words is supplemented after a short delay by a right parietal and medial occipital imagistic network. Hum Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Functional neural circuits for mental timekeeping
Authors: Stevens Michael C. , Kiehl Kent A. , Pearlson Godfrey , Calhoun Vince D.
Published: August 2006

Theories of mental timekeeping suggest frontostriatal networks may mediate performance of tasks requiring precise timing. We assessed whether frontostriatal networks are functionally integrated during the performance of timing tasks. Functional magnetic resonance imaging (fMRI) data from 31 healthy adults were collected during performance of several different types of discrete interval timing tasks. Independent component analysis (ICA) was used to examine functional connectivity within frontostriatal circuits. ICA identifies groups of spatially discrete brain regions sharing similar patterns of hemodynamic signal change over time. The results confirm the existence of a frontostriatal neural timing circuit that includes anterior cingulate gyrus, supplementary motor area, bilateral anterior insula, bilateral putamen/globus pallidus, bilateral thalamus, and right superior temporal gyrus and supramarginal gyrus. Several other distinct neural circuits were identified that may represent the neurobiological substrates of different information processing stages of mental timekeeping. Small areas of right cerebellum were engaged in several of these circuits, suggesting that cerebellar function may be important in, but not the primary substrate of, the mental timing tasks used in this experiment. These findings are discussed within the context of current biological and information processing models of neural timekeeping. Hum. Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Comparison of the neural basis for imagined writing and drawing
Authors: Harrington Greg S. , Farias Dana , Davis Christine H. , Buonocore Michael H.
Published: August 2006

Drawing and writing are complex processes that require the synchronization of cognition, language, and perceptual‐motor skills. Drawing and writing have both been utilized in the treatment of aphasia to improve communication. Recent research suggests that the act of drawing an object facilitated naming, whereas writing the word diminished accurate naming in individuals with aphasia. However, the relationship between object drawing and subsequent phonological output is unclear. Although the right hemisphere is characteristically mute, there is evidence from split‐brain research that the right hemisphere can integrate pictures and words, likely via a semantic network. We hypothesized that drawing activates right hemispheric and left perilesional regions that are spared in aphasic individuals and may contribute to semantic activation that supports naming. Eleven right‐handed subjects participated in a functional MRI (fMRI) experiment involving imagined drawing and writing and 6 of the 11 subjects participated in a second fMRI experiment involving actual writing and drawing. Drawing and writing produced very similar group activation maps including activation bilaterally in the premotor, inferior frontal, posterior inferior temporal, and parietal areas. The comparison of drawing vs. writing revealed significant differences between the conditions in areas of the brain known for language processing. The direct comparison between drawing and writing revealed greater right hemisphere activation for drawing in language areas such as Brodmann area (BA) 46 and BA 37. Hum. Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Disruption of the Arnt gene in endothelial cells causes hepatic vascular defects and partial embryonic lethality in mice
Authors: Yim Sun Hee , Shah Yatrik , Tomita Shuhei , Morris Douglas H. , Gavrilova Oksana , Lambert Gilles , Ward Jerrold M. , Gonzalez Frank J.
Published: August 2006

Vascular endothelial cells (ECs) play a critical role in angiogenesis and organogenesis, especially in embryonic liver development. Hypoxia-inducible transcription factors (Hifs) are a key trigger of hypoxic signals, a primary stimulus of angiogenesis. The aryl hydrocarbon receptor nuclear translocator (Arnt), also called Hif-1β, serves as an obligate heterodimerization partner of Hif-1α and Hif-2α. Using Cre-Lox technology, the mouse

Arnt

gene was specifically disrupted in endothelial cells. The resulting mice, designated ArntΔEC, developed impaired hepatic vasculature, liver necrosis, and degenerative lesions in cardiac myocytes at the late embryonic stage (E16.5-E18.5), leading to approximately 90% neonatal lethality. Low serum glucose, downregulation of glucose transporter-1 and glucose-6-phosphatase mRNA, and hepatocyte proliferation were observed in ArntΔEC embryos. Magnetic resonance imaging on E16.5 embryonic livers revealed that ArntΔEC mice had a significant volume of avascular region. ArntΔEC mice that survived to the adult stage were fertile, showed normal behavioral activity, but had smaller livers with mild portal fibrosis, dilated blood vessels, abnormal collagen accumulation, and remarkable iron deposition. ArntΔEC mice had reduced adiposity, impaired serum lipid homeostasis, and a higher respiratory exchange ratio, indicating they utilized relatively more carbohydrates than their ArntF/F counterparts.

In conclusion

, endothelial Arnt plays a pivotal role in embryonic liver development. Adult ArntΔEC mice carrying embryonic hepatic defects developed what was possibly an early stage of cirrhosis with consequences of limited oxygen availability and altered lipid metabolism.
Critical role of acidic sphingomyelinase in murine hepatic ischemia-reperfusion injury
Authors: Llacuna Laura , Marí Montserrat , Garcia-Ruiz Carmen , Fernandez-Checa José C. , Morales Albert
Published: August 2006

The molecular mechanisms of hepatic ischemia/reperfusion (I/R) damage are incompletely understood. We investigated the role of ceramide in a murine model of warm hepatic I/R injury. This sphingolipid induces cell death and participates in tumor necrosis factor (TNF) signaling. Hepatic ceramide levels transiently increased after the reperfusion phase of the ischemic liver in mice, because of an early activation of acidic sphingomyelinase (ASMase) followed by acid ceramidase stimulation.

In vivo

administration of an ASMase inhibitor, imipramine, or ASMase knockdown by siRNA decreased ceramide generation during I/R, and attenuated serum ALT levels, hepatocellular necrosis, cytochrome c release, and caspase-3 activation. ASMase-induced ceramide generation activated JNK resulting in BimL phosphorylation and translocation to mitochondria, as the inhibition of ASMase by imipramine prevented these events. In contrast, blockade of ceramide catabolism by N-oleyolethanolamine (NOE), a ceramidase inhibitor, enhanced ceramide levels and potentiated I/R injury compared with vehicle-treated mice. Pentoxifylline treatment prevented TNF upregulation and ASMase activation. Furthermore, 9 of 11 mice treated with imipramine survived 7 days after total liver ischemia, compared with 4 of 12 vehicle-treated mice, whereas 8 of 8 NOE-treated mice died within 2 days of total liver ischemia.

In conclusion

, ceramide generated from ASMase plays a key role in I/R-induced liver damage, and its modulation may be of therapeutic relevance.

Supplementary material for this article can be found on the HEPATOLOGY website
(http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).
The detection of bacterial DNA in blood of rats with CCl4-induced cirrhosis with ascites represents episodes of bacterial translocation
Authors: Guarner Carlos , González-Navajas José M. , Sánchez Elisabet , Soriando Germán , Francés Rubén , Chiva Maite , Zapater Pedro , Benlloch Susana , Muñoz Carlos , Pascual Sonia , Balanzó Joaquín , Pérez-Mateo Miguel , Such José
Published: August 2006

Bacterial DNA (bactDNA) is present in blood and ascitic fluid (AF) in a third of patients with cirrhosis and ascites, but whether this phenomenon represents episodes of bacterial translocation (BT), strictly considered when culture of mesenteric lymph nodes (MLNs) are positive, remains unknown. This study assessed the relationship between bactDNA detection in biological fluids and MLNs and went on to investigate the local and systemic inflammatory status according to its presence. Cirrhosis was induced in rats by ingestion of CCL4. A subgroup of five animals with cirrhosis received norfloxacin (5 mg/kg/day) for 7 days. MLNs and ascitic and pleural fluids were collected at laparotomy and cultured; samples were collected for identification of bactDNA and measurement of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and nitric oxide (NO). BactDNA was detected in MLNs in 12 of 19 animals (63.1%), corresponding in seven cases to culture-positive MLNs, and in five to culture-negative MLNs. BactDNA was detected in biological fluids in 11 of 19 animals (57.9%), and in all cases the same bacteria

spp.

detected in samples was present in MLNs. BactDNA was not detected in any biological sample from animals receiving norfloxacin. Tumor necrosis factor alpha (TNF-α), IL-6, and NO were similar in culture-positive and culture-negative/bactDNA-positive samples, and significantly higher than those observed in animals with culture-negative/bactDNA-negative MLNs, animals with cirrhosis that were receiving norfloxacin, and controls.

In conclusion

, the presence of bactDNA in biological fluids in rats with cirrhosis constitutes a marker of BT, and it is associated with a marked inflammatory response, independent of the result of the culture.
Investigation of the Lith1 candidate genes ABCB11 and LXRA in human gallstone disease
Authors: Schafmayer Clemens , Tepel Jürgen , Franke Andre , Buch Stephan , Lieb Sören , Seeger Marcus , Lammert Frank , Kremer Bernd , Fölsch Ulrich R. , Fändrich Fred , Schreiber Stefan , Hampe Jochen
Published: August 2006

Genetic susceptibility in the causation of gallbladder diseases was recognized as early as 1937. A major gallstone susceptibility locus (

Lith1

) was identified in 1995 by quantitative trait locus mapping in mice. Two attractive positional and functional candidate genes in

LXRA

and

ABCB11

are located in this interval.

ABCB11

is associated with progressive familial cholestasis. This study was undertaken to investigate

LXRA

and

ABCB11

as candidate genes for gallstone disease in humans. Eight hundred and ten patients who underwent cholecystectomy for symptomatic gallstone disease (median age of onset, 50 years) were compared with 718 sex-matched control individuals. Control individuals were sonographically free of gallstones. Haplotype tagging and all known coding single nucleotide polymorphisms (SNPs) were genotyped for

ABCB11

(n = 29) and

LXRA

(n = 10). The investigated high-risk patient sample provides a power of greater than 80% for the detection of odds ratios down to 1.55. No evidence of association of the two genes in the single point tagging markers, coding variants or in the sliding window haplotype analysis was detected (all nominal single-point

P

values ≥ .08).

In conclusion

, in the investigated German sample, no evidence of association of

ABCB11

and

LXRA

to gallstone susceptibility was detected. The gallstone trait is not allelic to progressive familial cholestasis at the

ABCB11

locus. Systematic fine mapping of the

Lith1

region is required to identify the causative genetic variants for gallstone in mice and humans.
Evolution of multi-drug resistant hepatitis B virus during sequential therapy
Authors: Yim Hyung Joon , Hussain Munira , Liu Ying , Wong Stephen N. , Fung Scott K. , Lok Anna S. F.
Published: August 2006

Multi-drug resistant hepatitis B virus (HBV) has been reported in hepatitis B patients who received sequential antiviral therapy.

In vitro

studies showed that HBV constructs with mutations resistant to lamivudine and adefovir have marked reduction in sensitivity to combination of lamivudine and adefovir, whereas constructs with mutations resistant to either drug remain sensitive to the other drug. We conducted this study to determine whether mutations conferring resistance to multiple antiviral agents co-locate on the same HBV genome

in vivo

and to describe the evolution of these mutations. Sera from six patients who had been found to have multi-drug resistant HBV mutations to lamivudine + adefovir, lamivudine + hepatitis B immunoglobulin (HBIG), or lamivudine + entecavir on direct sequencing were cloned after nested polymerase chain reaction (PCR). Analysis of 215 clones from 11 samples with multi-drug resistant mutations on direct sequencing showed that 183 (85%) clones had mutations to both therapies on the same genome; 31 clones had lamivudine-resistant mutants only. Clonal analysis of serial samples from three patients showed progressive evolution from all clones with lamivudine-resistant HBV mutations only to mixtures of clones that have multi-drug resistant mutations and clones that have lamivudine-resistant HBV mutations only, and ultimately all clones having multi-drug resistant HBV mutations.

In conclusion,

mutations conferring resistance to multiple antiviral agents co-locate on the same viral genome, suggesting that combination therapy directed against mutants resistant to each treatment may not be adequate in suppressing multi-drug resistant HBV.

De novo

combination therapy may prevent the emergence of multi-drug resistant mutants.
Hypercholesterolemia in rats with hepatomas: Increased oxysterols accelerate efflux but do not inhibit biosynthesis of cholesterol
Authors: Hirayama Takeshi , Honda Akira , Matsuzaki Yasushi , Miyazaki Teruo , Ikegami Tadashi , Doy Mikio , Xu Guorong , Lea Michael , Salen Gerald
Published: August 2006

Hypercholesterolemia is an important paraneoplastic syndrome in patients with hepatoma, but the nature of this defect has not yet been identified. We investigated the molecular mechanisms of hypercholesterolemia in a hepatoma-bearing rat model. Buffalo rats were implanted in both flanks with Morris hepatoma 7777 (McA-RH7777) cells. After 4 weeks, tumor weight was 5.5 ± 1.7 g, and serum cholesterol level increased from 60 ± 2 to 90 ± 2 mg/dL. Protein and mRNA expression of the ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1) was markedly higher in tumors than in livers. These increases were associated with activation of liver X receptor α (LXRα) as a result of the increased tissue oxysterol concentrations. The accumulation of oxysterols in the hepatomas appeared to be caused mainly by the upregulation of cholesterol biosynthesis, despite the increased tissue sterol concentrations. Overexpression of the sterol regulatory element-binding protein (SREBP) processing system relative to sterol concentration contributed to the resistance to sterols in this tumor. In addition, bile acid biosynthesis was inhibited despite the reduced expression of the small heterodimer partner (SHP) and activated LXRα, which also appeared to contribute to the accumulation of oxysterols followed by the acceleration of cholesterol efflux.

In conclusion

, hypercholesterolemia in McA-RH7777 hepatoma-bearing rats was caused by increased cholesterol efflux from tumors as a result of activation of LXRα. Overexpression of the SREBP processing system contributed to the activation of LXRα by maintaining high oxysterol levels in tissue.
Proteomic profiling of cholangiocarcinoma: Diagnostic potential of SELDI-TOF MS in malignant bile duct stricture
Authors: Scarlett Christopher J. , Saxby Alex J. , Nielsen AiQun , Bell Cameron , Samra Jaswinder S. , Hugh Thomas , Baxter Robert C. , Smith Ross C.
Published: August 2006

Proteomic techniques promise to improve the diagnosis of cholangiocarcinoma (CC) in both tissue and serum as histological diagnosis and existing serum markers exhibit poor sensitivities. We explored the use of surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) to identify potential protein biomarkers of CC. Twenty-two resected CC samples were compared with adjacent noninvolved bile duct tissue. Serum from patients with CC (n = 20) was compared with patients with benign disease (n = 20), and healthy volunteers (n = 25). Samples were analyzed on hydrophobic protein chips via SELDI-TOF MS, and classification models were developed using logistic regression and cross-validation analysis. Univariate analysis revealed 14 individual peaks differentially expressed between CC and bile duct tissue, 4 peaks between CC and benign disease, and 12 peaks between CC and sera of healthy volunteers. The 4,462 mass-to-charge serum peak had superior discriminatory ability to carbohydrate antigen 19.9 (CA19.9) and carcinoembryonic antigen (CEA) (

P

= .004; receiver operating characteristic [ROC] area under the curve [AUC] = 0.76, 0.73, and 0.70, respectively). The training models developed panels of peaks that distinguished CC from bile duct tissue (92.5% sensitivity, 92.3% specificity; ROC AUC = 0.96), CC from benign serum (65.0% sensitivity, 70.0% specificity; ROC AUC = 0.83), and CC from sera of healthy volunteers (75.0% sensitivity, 100% specificity; ROC AUC = 0.92). Serum results were further improved with the inclusion of CA19.9 and CEA (ROC AUC = 0.86 and 0.99 for CC vs benign and healthy volunteer serum, respectively).

In conclusion

, biomarker panels are capable of distinguishing CC from nonmalignant tissue; serum markers have important diagnostic implications for unknown bile duct stricture.
Pegylated interferon alpha-2b as monotherapy or in combination with ribavirin in chronic hepatitis delta
Authors: Niro Grazia Anna , Ciancio Alessia , Gaeta Giovanni Battista , Smedile Antonina , Marrone Aldo , Olivero Antonella , Stanzione Maria , David Ezio , Brancaccio Giuseppina , Fontana Rosanna , Perri Francesco , Andriulli Angelo , Rizzetto Mario
Published: August 2006

Therapy of chronic hepatitis delta with standard interferon therapy has met with limited efficacy. This study was designed to examine the efficacy and safety of peginterferon with or without ribavirin. Thirty-eight serum hepatitis B surface antigen- and HDV RNA-positive patients with alanine aminotransferase (ALT) more than 1.5 times the upper normal limit received peginterferon alpha-2b (1.5 μg/kg) alone as monotherapy (n = 16) or in combination with ribavirin (n = 22), for 48 weeks. Thereafter, all the patients were maintained on peginterferon for 24 weeks and followed for 24 weeks off therapy. The primary end point studied was the virological and biochemical response at the end of follow-up. HDV RNA was determined by single or nested polymerase chain reaction assays. Twenty-seven patients (71%), 11 receiving monotherapy and 16 receiving the combination treatment, completed the follow-up. At the end of treatment, a virological response was observed in 3 of the patients treated with peginterferon (19%) and in 2 of the patients treated with combination therapy (9%), and a biochemical response was observed in 6 (37.5%) and 9 patients (41%), respectively. In nonresponders, ALT diminished from a mean of 174 ± 53 to 86 ± 41 IU/L. At the end of follow-up, serum HDV RNA was negative in 8 patients (21%), and a biochemical response was detected in 10 patients (26%). Treatment was discontinued in 25% of the patients, and dosing was modified in 58%.

In conclusion

, a prolonged course of peginterferon alpha-2b resulted in clearance of serum HDV RNA and ALT normalization in a fifth of patients with chronic hepatitis D, while ribavirin had no effect on the viral clearance rate. Overall tolerance of therapy was poor.
Ischemic preconditioning of the murine liver protects through the Akt kinase pathway
Authors: Izuishi Kunihiko , Tsung Allan , Hossain Mohammad Akram , Fujiwara Masao , Wakabayashi Hisao , Masaki Tsutomu , Billiar Timothy R. , Maeta Hajime
Published: August 2006

Hepatic ischemia-reperfusion (I/R) injury occurs in the settings of transplantation, trauma, and elective liver resection. Ischemic preconditioning has been used as a strategy to reduce inflammation and organ damage from I/R of the liver. However, the mechanisms involved in this process are poorly understood. We examined the role of the phosphatidylinositol 3 (PI3) kinase/Akt-signaling pathway during hepatic ischemic preconditioning (IPC). Prior to a prolonged warm ischemic insult, BALB/c mice were subjected to a 20-minute IPC period consisting of 10 minutes of ischemia and 10 minutes of reperfusion. Mice undergoing IPC demonstrated a significantly greater level and earlier activation of Akt in the liver compared with control animals. IPC also resulted in markedly less hepatocellular injury and improved survival compared with control animals. Akt activation associated with hepatic IPC suppressed the activity of several modulators of apoptosis, including Bad, glycogen synthase kinase β, and caspase-3. In addition, IPC also inhibited the activities of c-Jun

N

-terminal kinase and nuclear factor κB after I/R. Pretreatment of mice with PI3 kinase inhibitors completely abolished Akt phosphorylation and the protective effects seen with IPC.

In conclusion

, these results indicate that the PI3 kinase/Akt pathway plays an essential role in the protective effects of IPC in hepatic I/R injury. Modulation of this pathway may be a potential strategy in clinical settings of ischemic liver injury to decrease organ damage.

Supplementary material for this article can be found on the HEPATOLOGY website
(http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).
Intrahepatic levels and replicative activity of covalently closed circular hepatitis B virus DNA in chronically infected patients
Authors: Laras Andreas , Koskinas John , Dimou Evangelini , Kostamena Ageliki , Hadziyannis Stephanos J.
Published: August 2006

Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) is responsible for viral persistence in the natural course of chronic HBV infection and during prolonged antiviral therapy and serves as the template for the production of HBV pregenomic RNA (pgRNA), the primary step in HBV replication. In this study, we have developed and applied sensitive and specific quantitative real-time polymerase chain reaction (PCR) assays for the measurement of intrahepatic concentration, pgRNA production, and replicative activity of cccDNA in liver biopsy samples from 34 non-treated patients with chronic hepatitis B (CHB); 12 hepatitis B e antigen (HBeAg)(+) and 22 HBeAg(−). Median copy number for cccDNA was 1.5 per cell and for pgRNA significantly higher, 6.5 copies per cell, with a good correlation between cccDNA and pgRNA levels in all samples. In HBeAg(−) patients, median values of cccDNA and pgRNA levels were 10-fold and 200-fold lower than in HBeAg(+), respectively, reflecting the differences in viral activity and clinical characteristics of the two groups. Furthermore, the replicative activity of intrahepatic cccDNA was significantly lower in HBeAg(−) patients harboring mutant HBV strains than in HBeAg(+) patients: median 3.5 versus 101 pgRNA copies per cccDNA molecule.

In conclusion

, the levels of both HBV cccDNA, a marker of HBV persistence, and pgRNA, an indicator of viral replication, in the liver of chronically infected patients correlate with viral activity and the phase of HBV infection. The combined measurement of cccDNA and pgRNA levels provides valuable information on the presence and replicative activity of intrahepatic HBV cccDNA.
Indeterminate acute liver failure: A riddle wrapped in a mystery inside an enigma
Authors: Davern Timothy J.
Published: August 2006

Fulminant hepatitis of unknown origin remains a significant cause of mortality, for which liver transplantation is often considered as the only therapeutic option. In retrospective studies, human herpesvirus 6 (HHV-6) infections have been associated with such diseases, but the diagnosis of HHV-6 infection of the liver is rarely established during the acute phase of liver failure. Using real-time polymerase chain reaction (PCR), we diagnosed two cases of severe acute liver failure (ALF) related to HHV-6 occurring in immunocompetent young adults. Both cases had a favourable outcome, one after valganciclovir therapy and one after liver transplantation associated with ganciclovir. Viral origin was evidenced in each case by the detection of high amounts of HHV-6 DNA in liver tissue by the PCR assay. The decrease of intrahepatic viral load after therapeutic intervention was also monitored by quantitative PCR and paralleled in the two cases the clinical improvement. Diagnosis of HHV-6 infection must be systematically evoked in case of unexplained ALF, since it might lead to specific therapeutic interventions, in addition to liver transplantation.
The effect of single oral low-dose losartan on posture-related sodium handling in post-TIPS ascites-free cirrhosis
Authors: Therapondos George , Hol Lieke , Benjaminov Fabiana , Wong Florence
Published: August 2006

Post-TIPS ascites-free patients with cirrhosis and previous refractory ascites demonstrate subtle sodium retention when challenged with a high sodium load. This is also observed in pre-ascitic patients with cirrhosis. This phenomenon is dependent on an intrarenal angiotensin II (ANG II) mechanism related to the assumption of erect posture. We investigated whether similar mechanisms were involved in post-TIPS ascites-free patients, by studying 10 patients with functioning TIPS and no ascites. We measured the effect of changing from supine to erect posture on sodium excretion at baseline and after single oral low dose losartan (7.5 mg) which has been shown to blunt proximal and distal tubular sodium reabsorption in pre-ascites. At baseline, the assumption of erect posture produced a reduction in sodium excretion (from 0.30 ± 0.06 to 0.13 ± 0.02 mmol/min,

P

= .05), which was mainly due to an increase in proximal tubular reabsorption of sodium (PTRNa) (69.7 ± 3.1% to 81.1 ± 1.8%,

P

= .003). The administration of losartan resulted in a blunting of PTRNa (supine 69.7 ± 3.1% to 63.9 ± 3.9%,

P

= .01 and erect 81.1 ± 1.8% to 73.8 ± 2.4%,

P

= .01), accompanied by an increased distal tubular reabsorption of sodium in both postures, with no overall improvement in sodium excretion on standing.

In conclusion

, post-TIPS ascites-free patients with cirrhosis exhibit erect posture-induced sodium retention. We speculate that (1) this effect is partly mediated by the effect of ANG II on PTRNa and (2) that the inability of low dose losartan to block the erect posture-induced sodium retention may be related to the erect posture-induced rise in aldosterone which is unmodified by losartan.
Lack of UCP2 reduces fas-mediated liver injury in ob/ob mice and reveals importance of cell-specific UCP2 expression
Authors: Fülöp Péter , Derdák Zoltán , Sheets Anthony , Sabo Edmond , Berthiaume Eric P. , Resnick Murray B. , Wands Jack R. , Paragh György , Baffy György
Published: August 2006

Fatty liver is vulnerable to conditions that challenge hepatocellular energy homeostasis. Lipid-laden hepatocytes highly express uncoupling protein-2 (UCP2), a mitochondrial carrier that competes with adenosine triphosphate (ATP) synthesis by mediating proton leak. However, evidence for a link between UCP2 expression and susceptibility of liver to acute injury is lacking. We asked whether absence of UCP2 protects

ob/ob

mice from Fas-mediated acute liver damage. UCP2-deficient

ob/ob

mice (

ob/ob:ucp2

−/−

) and UCP2-competent littermates (

ob/ob:ucp2

+/+) received a single dose of agonistic anti-Fas antibody (Jo2). Low-dose Jo2 (0.15 mg/kg intraperitoneally) caused less serum alanine aminotransferase (ALT) elevation and lower apoptosis rates in

ob/ob:ucp2

−/−

mice. High-dose Jo2 (0.40 mg/kg intraperitoneally) proved uniformly fatal; however,

ob/ob:ucp2

−/−

mice survived longer with less depletion of liver ATP stores, indicating that fatty hepatocytes may benefit from lack of UCP2 during Jo2 challenge. Although UCP2 reportedly controls mitochondrial oxidant production, its absence had no apparent effect on fatty liver tissue malondialdehyde levels augmented by Jo2. This finding prompted us to determine UCP2 expression in Kupffer cells, a major source of intrahepatic oxidative stress. UCP2 expression was found diminished in Kupffer cells of untreated

ob/ob:ucp2

+/+ mice, conceivably contributing to increased oxidative stress in fatty liver and limiting the impact of UCP2 ablation.

In conclusion

, whereas UCP2 abundance in fatty hepatocytes exacerbates Fas-mediated injury by compromising ATP stores, downregulation of UCP2 in Kupffer cells may account for persistent oxidative stress in fatty liver. Our data support a cell-specific approach when considering the therapeutic effects of mitochondrial uncoupling in fatty liver disease.
Uric acid and anti-TNF antibody improve mitochondrial dysfunction in ob/ob mice
Authors: García-Ruiz Inmaculada , Rodríguez-Juan Cristina , Díaz-Sanjuan Teresa , del Hoyo Pilar , Colina Francisco , Muñoz-Yagüe Teresa , Solís-Herruzo José A.
Published: August 2006

The mechanisms responsible for low mitochondrial respiratory chain (MRC) activity in the liver of patients with nonalcoholic steatohepatitis are unknown. In this study, we examined the cause of this dysfunction in ob/ob mice. Forty-six mice were distributed in six groups: group I: C57BL/6J mice; group II: C57BL/6J Lep(−/−) mice (ob/ob); group III, ob/ob mice treated with manganese [III] tetrakis (5,10,15,20 benzoic acid) porphyrin (MnTBAP); group IV, ob/ob mice treated with IgG1 immunoglobulin; group V, ob/ob mice treated with anti-TNF antibody; group VI: ob/ob mice treated with uric acid. In liver tissue, we measured MRC activity, fatty acid β-oxidation, tumor necrosis factor (TNF), inducible nitric oxide synthase (iNOS), 3-tyrosine-nitrated proteins, 3-tyrosine-nitrated mitochondrial proteins, including cytochrome

c

and ND4 subunit of complex I. MRC activity was decreased in ob/ob mice. TNF levels, iNOS protein expression, and tyrosine nitrated proteins were markedly increased in the liver of ob/ob mice. In these animals, mitochondrial proteins were markedly tyrosine nitrated, particularly the ND4 subunit of complex I and cytochrome

c

. Treatment of these animals with uric acid, a peroxynitrite scavenger, anti-TNF antibody, or MnTBAP decreased tyrosine nitrated proteins, improved the activity of MRC complexes, and led to a marked regression of hepatic steatosis and inflammation.

In conclusion

, MRC dysfunction and liver lesions found in ob/ob mice are likely to reflect the tyrosine nitration of mitochondrial proteins by peroxynitrite or a peroxynitrite-derivate radical. Increased hepatic TNF and iNOS expression might enhance peroxynitrite formation and inhibition of MRC complexes.

Supplementary material for this article can be found on the HEPATOLOGY website
(http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).
Involvement of integrin-linked kinase in carbon tetrachloride–induced hepatic fibrosis in rats
Authors: Zhang Yining , Ikegami Tadashi , Honda Akira , Miyazaki Teruo , Bouscarel Bernard , Rojkind Marcos , Hyodo Ichinosuke , Matsuzaki Yasushi
Published: August 2006

Integrin-linked kinase (ILK) is a multidomain focal adhesion protein implicated in signal transduction between integrins and growth factor receptors. Although its expression is upregulated in pulmonary and renal fibrosis, its role in the development of hepatic fibrosis remains to be determined. Therefore, we considered it important to investigate whether ILK is involved in activation of hepatic stellate cells and thus plays a role in the development of hepatic fibrosis. Immunohistochemical analysis of liver sections obtained from rats with CCl4-induced cirrhosis revealed increased expression and colocalization of ILK and alpha-smooth muscle actin in hepatic stellate cells in perisinusoidal areas. In addition, hepatic stellate cells isolated from fibrotic livers expressed high levels of ILK and alpha-smooth muscle actin, and their expression was sustained in culture. In contrast, hepatic stellate cells (HSCs) isolated from normal rat liver did not express ILK, but its expression was increased when the cells were activated in culture. Our studies also showed that ILK is involved in the phosphorylation of ERK 1/2, p38 MAPK, JNK, and PKB and that selective inhibition of ILK expression by siRNA results in a significant decrease in their phosphorylation. These changes were accompanied by significant inhibition of cell spreading and migration without affecting cell proliferation.

In conclusion

, ILK plays a key role in HSC activation and could be a possible target for antifibrogenic therapy.
CD4+ immune escape and subsequent T-cell failure following chimpanzee immunization against hepatitis C virus
Authors: Puig Montserrat , Mihalik Kathleen , Tilton John C. , Williams Ollie , Merchlinsky Michael , Connors Mark , Feinstone Stephen M. , Major Marian E.
Published: August 2006

Hepatitis C is a major cause of chronic liver disease, with 170 million individuals infected worldwide and no available vaccine. We analyzed the effects of an induced T-cell response in 3 chimpanzees, targeting nonstructural proteins in the absence of neutralizing antibodies. In all animals the specific T-cell response modified the outcome of infection, producing a 10- to 1,000-fold reduction in peak virus titers. The challenge of 2 immunized animals that had been previously exposed to hepatitis C virus resulted in subclinical infections. Immune responses in the third animal, naive prior to immunization, limited viral replication immediately, evidenced by a 30-fold reduction in virus titer by week 2, declining to a nonquantifiable level by week 6. After 10 weeks of immunological control, we observed a resurgence of virus, followed by progression to a persistent infection. Comparing virus evolution with T-cell recognition, we demonstrated that: (i) resurgence was concomitant with the emergence of new dominant viral populations bearing single amino acid changes in the NS3 and NS5A regions, (ii) these mutations resulted in a loss of CD4+ T-cell recognition, and (iii) subsequent to viral resurgence and immune escape a large fraction of NS3-specific T cells became impaired in their ability to secrete IFN-γ and proliferate. In contrast, NS3-specific responses were sustained in the recovered/immunized animals presenting with subclinical infections.

In conclusion

, viral escape from CD4+ T cells can result in the eventual failure of an induced T-cell response that initially controls infection. Vaccines that can induce strong T-cell responses prior to challenge will not necessarily prevent persistent HCV infection.
Hepatitis C virus entry: Molecular biology and clinical implications
Authors: Barth Heidi , Liang Jake T. , Baumert Thomas F.
Published: August 2006

With an estimated 170 million infected individuals, hepatitis C virus (HCV) has a major impact on public health. A vaccine protecting against HCV infection is not available, and current antiviral therapies are characterized by limited efficacy, high costs, and substantial side effects. Binding of the virus to the cell surface followed by viral entry is the first step in a cascade of interactions between virus and the target cell that is required for the initiation of infection. Because this step represents a critical determinant of tissue tropism and pathogenesis, it is a major target for host cell responses such as antibody-mediated virus-neutralization—and a promising target for new antiviral therapy. The recent development of novel tissue culture model systems for the study of the first steps of HCV infection has allowed rapid progress in the understanding of the molecular mechanisms of HCV binding and entry. This review summarizes the impact of recently identified viral and host cell factors for HCV attachment and entry. Clinical implications of this important process for the pathogenesis of HCV infection and novel therapeutic interventions are discussed.
Efficacy of peginterferon alpha-2b in chronic hepatitis delta: Relevance of quantitative RT-PCR for follow-up
Authors: Castelnau Corinne , Le Gal Frédéric , Ripault Marie-Pierre , Gordien Emmanuel , Martinot-Peignoux Michelle , Boyer Nathalie , Pham Bach-Nga , Maylin Sarah , Bedossa Pierre , Dény Paul , Marcellin Patrick , Gault Elyanne
Published: August 2006

Hepatitis delta virus (HDV) can cause severe acute and chronic liver disease in patients infected by hepatitis B virus. Interferon alpha at high doses, although poorly efficient, is the only treatment reported to provide some benefit in chronic hepatitis delta. Pegylated interferon alpha (PEG-IFN) has not yet been evaluated. Treatment is usually monitored by the qualitative detection of HDV-RNA in serum. In this study, safety and efficacy of PEG-IFN were assessed in chronic hepatitis delta, and serum HDV-RNA kinetics were determined using quantitative RT-PCR. Fourteen patients with chronic hepatitis delta received subcutaneous PEG-IFN alpha-2b during 12 months (1.5 μg/kg per week). Serum HDV-RNA was quantified at initiation and during the course of therapy, and during the posttreatment follow-up period, which ranged from 6 to 42 months (median 16 months). PEG-IFN alpha-2b was well tolerated, inducing no serious adverse effect. Sustained biochemical response was obtained in 8 patients (57%). At the end of treatment, 8 patients (57%) had achieved virological response (undetectable HDV-RNA). Sustained virological response throughout the posttreatment follow-up period was observed in 6 patients (43%). HDV-RNA kinetics were predictive of the response: after 3 months of PEG-IFN, HDV-RNA levels were significantly lower in the responders than in the nonresponders group (

P

= .018). After 6 months of therapy, a negative HDV-RNA was predictive of sustained response (

P

= .021).

In conclusion

, this preliminary study indicates that PEG-IFN alpha-2b is safe and efficient for treatment of chronic hepatitis delta. The follow-up of HDV-RNA levels during therapy, which allows the differentiation of various profiles of virological responses, improves treatment monitoring.
Primary sclerosing cholangitis: Summary of a workshop
Authors: LaRusso Nicholas F. , Shneider Benjamin L. , Black Dennis , Gores Gregory J. , James Stephen P. , Doo Edward , Hoofnagle Jay H.
Published: August 2006

Primary sclerosing cholangitis (PSC) is a rare but important liver disease that leads to cirrhosis and need for liver transplantation in a high proportion of cases. The disease occurs in approximately 1 per 100,000 population per year, usually presents in adulthood, and affects men more often than women. Typical serum biochemical results, autoantibodies and liver biopsy are suggestive but not diagnostic of PSC, the diagnosis requiring cholangiographic demonstration of stricturing and dilatation of the intra- and/or extra-hepatic bile ducts. The natural history of PSC is variable, the average survival being 12 to 17 years. The cause of PSC is still unknown. Although considered an autoimmune disease, PSC has several atypical features and a strong genetic component. The therapy of PSC is unsatisfactory. Standard doses of ursodeoxycholic acid (UDCA) lead to improvements in biochemical abnormalities but not in histology, cholangiographic appearance or survival. Several innovative therapies have been tried in PSC, but with scant evidence of benefit. For patients with high grade strictures, endoscopic dilatation is beneficial. Liver transplantation is successful for end-stage liver disease due to PSC and improves survival. PSC may recur after transplantation but is rarely progressive. The most dreaded complication of PSC is cholangiocarcinoma. Diagnosis of this highly malignant tumor is difficult, and there are no biomarkers for its early detection. Liver transplantation for cholangiocarcinoma has an exceedingly poor outcome, although transplantation with neoadjuvant chemoirradiation holds promise in selected patients. Thus, significant opportunities remain for basic and clinical research into the cause, natural history, and therapy of PSC.
Global challenges in liver disease
Authors: Williams Roger
Published: August 2006

Immigration, cheap air travel, and globalization are all factors contributing to a worldwide spread of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. End-stage chronic liver disease (ESLD) as a result of co-infection with HBV/HCV is now the major cause of death for individuals who have been infected with the HIV virus. The high incidence of HCV infection in Egypt—the legacy left from the mass use of tartar emetic to eradicate schistosomiasis, as in other high prevalence areas—will take years to reduce. Steatohepatitis due to non-alcoholic fatty liver disease is developing into a new and major health problem as a result of rising levels of obesity in populations worldwide. Hepatic steatosis also has an adverse influence on the progression of other liver diseases including chronic HCV infection and alcoholic liver disease. In many countries, considerable public concern is on the rise due to increased levels of alcohol consumption adversely affecting younger and affluent age groups. With the rising prevalence of cirrhosis, primary hepatocellular carcinoma (HCC) is increasing in frequency as is that of primary intrahepatic cholangiocarcinoma. Finally, despite the successes of liver transplantation, many deserving patients are not getting transplants due to low levels of cadaver organ donation in many countries, thereby increasing pressures on the use of living donor liver transplantation. Only through a concerted effort from governments, health agencies, healthcare professionals at all levels, and the pharmaceutical industry can this grim outlook for liver disease worldwide be reversed.
Methylene‐Bridged Metallocenes with 2,2′‐Methylenebis[1H‐inden‐1‐yl] Ligands: Synthesis, Characterization, and Polymerization Catalysis of a Synthetically Simple Class of C2‐ and C2v‐Symmetric ansa‐Metallocenes
Authors: Resconi Luigi , Camurati Isabella , Fiori Cristina , Balboni Davide , Mercandelli Pierluigi , Sironi Angelo
Published: August 2006

The acid‐catalyzed reaction between formaldehyde and 1H‐indene, 3‐alkyl‐ and 3‐aryl‐1H‐indenes, and six‐membered‐ring substituted 1H‐indenes, with the 1H‐indene/CH2O ratio of 2 : 1, at temperatures above 60° in hydrocarbon solvents, yields 2,2′‐methylenebis[1H‐indenes] 1–8 in 50–100% yield. These 2,2′‐methylenebis[1H‐indenes] are easily deprotonated by 2 equiv. of BuLi or MeLi to yield the corresponding dilithium salts, which are efficiently converted into ansa‐metallocenes of Zr and Hf. The unsubstituted dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1H‐inden‐1‐yl]}zirconium ([ZrCl2(1′)]) is the least soluble in organic solvents. Substitution of the 1H‐indenyl moieties by hydrocarbyl substituents increases the hydrocarbon solubility of the complexes, and the presence of a substituent larger than a Me group at the 1,1′ positions of the ligand imparts a high diastereoselectivity to the metallation step, since only the racemic isomers are obtained. Methylene‐bridged ‘ansa‐zirconocenes’ show a noticeable open arrangement of the bis[1H‐inden‐1‐yl] moiety, as measured by the angle between the planes defined by the two π‐ligands (the ‘bite angle’). In particular, of the ‘zirconocenes’ structurally characterized so far, the dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[4,7‐dimethyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl2(5′)] is the most open. The mixture [ZrCl2(1′)]/methylalumoxane (MAO) is inactive in the polymerization of both ethylene and propylene, while the metallocenes with substituted indenyl ligands polymerize propylene to atactic polypropylene of a molecular mass that depends on the size of the alkyl or aryl groups at the 1,1′ positions of the ligand. Ethene is polymerized by rac‐dichloro{(1,1′,2,2′,3,3′,3a,3′a,7a,7′a‐η)‐2,2′‐methylenebis[1‐methyl‐1H‐inden‐1‐yl]}zirconium ([ZrCl2(2′)])/MAO to polyethylene waxes (average degree of polymerization ca. 100), which are terminated almost exclusively by ethenyl end groups. Polyethylene with a high molecular mass could be obtained by increasing the size of the 1‐alkyl substituent.