bluuebunny/crossref_metadata_2025 huggingface dataset:
Bayesian density estimation using ranked set samples
Authors: Ghosh Kaushik , Tiwari Ram C.
Published: November 2004

In this article, we present a Bayesian approach for estimating the underlying density using a ranked set sample. We assume that the observations are generated from a Dirichlet process mixture model. Density (as well as moments) of future values generated from the process are estimated through Markov chain Monte Carlo simulations. This approach extends earlier work on density estimation based on a Dirichlet process prior from a simple random sample to a ranked set sample. We carry out a simulation study using a normal kernel to compare the effect of using a simple random sample versus a ranked set sample on the predictive density. We show that the Bayesian density estimate resulting from a ranked set sample has a smaller average mean squared error than that from a simple random sample. Additionally, the average Kullback–Leibler distance of the density estimate based on the ranked set sample is shown to be closer to zero than that based on the corresponding simple random sample. We illustrate our method by applying it to shrub data available in the literature. Copyright © 2004 John Wiley & Sons, Ltd.
Comparing the accuracy of density forecasts from competing models
Authors: Sarno Lucio , Valente Giorgio
Published: November 2004

A rapidly growing literature emphasizes the importance of evaluating the forecast accuracy of empirical models on the basis of density (as opposed to point) forecasting performance. We propose a test statistic for the null hypothesis that two competing models have equal density forecast accuracy. Monte Carlo simulations suggest that the test, which has a known limiting distribution, displays satisfactory size and power properties. The use of the test is illustrated with an application to exchange rate forecasting. Copyright © 2004 John Wiley & Sons, Ltd.
Microcell‐mediated transfer of chromosome 4 into HeLa cells suppresses telomerase activity
Authors: Backsch Claudia , Wagenbach Nikola , Nonn Marion , Leistritz Sabine , Stanbridge Eric , Schneider Achim , Dürst Matthias
Published: November 2004

Telomerase activity can be detected in most human cancers and immortal cell lines. In contrast, the lack of telomerase activity in normal diploid fibroblasts has been correlated with progressive reduction of telomere lengths to critically short sizes followed by the cessation of cell division and the onset of senescence. Several investigators have provided evidence for the localization of a telomerase suppressor gene on chromosome 3. The aim of our study was to determine whether other chromosomes are involved in telomerase repression. Beside human chromosome 3 (serving as positive control), chromosomes 4, 6, and 11 were introduced into HeLa cells via microcell‐mediated chromosome transfer. Telomerase activity from different hybrid cell lysates was determined at an early time point after fusion using a Telomerase ELISA kit. Strong repression of telomerase activity was only found in a subset of HeLa hybrids in which chromosome 3 or chromosome 4 had been introduced. Telomerase suppression induced by chromosome 3 or 4 transfer was paralleled by a high frequency (30% or 43%, respectively) of a senescent‐like phenotype. Chromosomes 6 and 11, the functional loss of which is also implicated in cervical cancer, had no effect. These results indicate that normal human chromosomes 3 and 4 carry a gene or genes that suppress telomerase activity and induce cellular senescence in HeLa cells.©2001 Wiley‐Liss, Inc.
Characterization of oncogene dysregulation in multiple myeloma by combined FISH and DNA microarray analyses
Authors: Fabris Sonia , Agnelli Luca , Mattioli Michela , Baldini Luca , Ronchetti Domenica , Morabito Fortunato , Verdelli Donata , Nobili Lucia , Intini Daniela , Callea Vincenzo , Stelitano Caterina , Lombardi Luigia , Neri Antonino
Published: November 2004

Chromosomal translocations involving the immunoglobulin heavy chain (IGH) locus and various partner loci frequently are associated with multiple myeloma (MM). We investigated the expression profiles of the FGFR3/MMSET, CCND1, CCND3, MAF, and MAFB genes, which are involved in t(4;14)(p16.3;q32), t(11;14)(q13;q32), t(6;14)(p21;q32), t(14;16)(q32;q23), and t(14;20)(q32;q12), respectively, in purified plasma cell populations from 39 MMs and six plasma cell leukemias (PCL) by DNA microarray analysis and compared the results with the presence of translocations as assessed by dual‐color FISH or RT‐PCR. A t(4;14) was found in 6 MMs, t(11;14) in 9 MMs and 1 PCL, t(6;14) in 1 MM, t(14;16) in 2 MMs and 1 PCL, and t(14;20) in 1 PCL. In all cases, the translocations were associated with the spiked expression of target genes. Furthermore, gene expression profiling enabled the identification of putative translocations causing dysregulation of CCND1 (1 MM and 1 PCL) and MAFB (1 MM and 1 PCL) without any apparent involvement of immunoglobulin loci. Notably, all of the translocations were mutually exclusive. Markedly increased MMSET expression was found in 1 MM showing associated FGFR3 and MMSET signals on an unidentified chromosome. Our data suggest the importance of using combined molecular cytogenetic and gene expression approaches to detect genetic aberrations in MM. © 2004 Wiley‐Liss, Inc.
Translocation t(X;11)(q13;q23) in B‐cell chronic lymphocytic leukemia disrupts two novel genes
Authors: Kalla Claudia , Nentwich Hagen , Schlotter Magdalena , Mertens Daniel , Wildenberger Kathrin , Döhner Hartmut , Stilgenbauer Stephan , Lichter Peter
Published: November 2004

Deletion of chromosome region 11q22–q23 defines a subgroup of patients with B‐cell chronic lymphocytic leukemia (B‐CLL) characterized by poor survival. Although the tumor‐suppressor gene ATM in the consensus deletion region was found to be biallelically inactivated in about one third of B‐CLL cases, in the majority of those who have this deletion, inactivation of the remaining ATM allele was not observed. To identify a second disease‐associated gene, we investigated two B‐CLL cases with translocation breakpoints in the critical 11q23 deletion region. In one case, a t(X;11)(q13;q23) was cloned and two novel genes were isolated. The breakpoint on 11q23 affected the ARHGAP20 gene, which encodes a protein predicted to be involved in the regulation of Rho family GTPases. The breakpoint on Xq13 occurred in BRWD3, which codes for a putative novel transcription factor. The rearrangement of ARHGAP20 and BRWD3 did not result in fusion transcripts, but it disrupted both genes. Mutation analysis of 28 B‐CLL samples with monoallelic deletions and two B‐CLL samples with 11q23 translocations detected no deleterious mutation in the remaining copy of ARHGAP20. Quantitative expression analysis in 22 B‐CLLs revealed significant up‐regulation of ARHGAP20 in CLL B cells, whereas BRWD3 was slightly down‐regulated. Thus, deregulation of ARHGAP20 by altered gene expression or by gene disruption (but not point mutation) might be a general molecular mechanism of B‐CLL leukemogenesis. © 2004 Wiley‐Liss, Inc.
Sampling and analyzing metals in soils for archaeological prospection: A critique
Authors: Haslam Rob , Tibbett Mark
Published: November 2004

This paper presents a critique of current methods of sampling and analyzing soils for metals in archaeological prospection. Commonly used methodologies in soil science are shown to be suitable for archaeological investigations, with a concomitant improvement in their resolution. Understanding the soil‐fraction location, concentration range, and spatial distribution of autochthonous (native) soil metals is shown to be a vital precursor to archaeological‐site investigations, as this is the background upon which anthropogenic deposition takes place. Nested sampling is suggested as the most cost‐effective method of investigating the spatial variability in the autochthonous metal concentrations. The use of the appropriate soil horizon (or sampling depth) and point sampling are critical in the preparation of a sampling regime. Simultaneous extraction is proposed as the most efficient method of identifying the location and eventual fate of autochthonous and anthropogenic metals, respectively. © 2004 Wiley Periodicals, Inc.
Wadi Bakht revisited: Holocene climate change and prehistoric occupation in the Gilf Kebir region of the Eastern Sahara, SW Egypt
Authors: Linstädter Jörg , Kröpelin Stefan
Published: November 2004

Geoarchaeological and chronological evidence from the remote Gilf Kebir Plateau in southwest Egypt suggests a new model for the influence of early and mid‐Holocene precipitation regimes on land‐use strategies of prehistoric settlers in what is now the center of the largest hyperarid area on earth. We hypothesize that the quantitatively higher, daytime, monsoon summer rainfall characteristic of the early Holocene (9300–5400 14C yr B.P./8400–4300 yr B.C.) resulted in less grass growth on the plateau compared to the winter rains that presumably fell in the cool nights during the terminal phase of the Holocene pluvial (5400–4500 yr B.P./4300–3300 yr B.C.). The unparalleled climatic transition at 5400 yr B.P. (4300 yr B.C.) caused a fundamental environmental change that resulted in different patterns of human behavior, economy, and land use in the canyon‐like valleys and on the plains surrounding the plateau. The model emphasizes the crucial impact of seasonal rainfall distribution on cultural landscapes in arid regions and the lower significance of annual precipitation rates, with implications for future numeric climate models. It also serves as an example of how past climate changes have affected human societies. © 2004 Wiley Periodicals, Inc.
Subsource characterization: Obsidian utilization of subsources of the Coso volcanic field, Coso Junction, California, USA
Authors: Ericson Jonathon E. , Glascock Michael D.
Published: November 2004

Six chemical subsource groups were identified in the analysis of 84 obsidian samples collected from subsource locations at Coso volcanic field, California. In prehistoric times, Coso provided obsidian for artifacts found from San Francisco Bay to San Diego to Death Valley to the eastern Mojave Desert. Subsource groups were defined by instrumental neutron activation analysis (INAA) of 29 elements followed by cluster analysis, principal component analysis, and bivariate plotting. The new data are compared to previously published INAA and X‐ray fluorescence data. Characterization of 55 obsidian artifacts from archaeological sites located approximately 100 miles from Coso suggests preferential usage of specific subsources as a function of the directionality of travel. The results are consistent with a bimodal (resident and itinerant) model of procurement. This research illustrates the importance of accurate sourcing of obsidian artifacts when attempting to define subsource usage. © 2004 Wiley Periodicals, Inc.
Bile acids suppress the secretion of very-low-density lipoprotein by human hepatocytes in primary culture
Authors: Lin Y , Havinga R , Verkade H J , Moshage H , Slooff M J , Vonk R J , Kuipers F
Published: November 2004

The existence of a relationship between bile acid and triacylglycerol metabolism in humans has been established, but the underlying mechanism and its physiological relevance have remained unclear. We have studied the effects of bile acids on the secretion of very-low-density lipoprotein (VLDL)-associated triacylglycerol, using [3H]glycerol labeling technique, and apolipoprotein B (apoB) in human hepatocytes in primary culture. Human hepatocytes secrete nascent VLDL with an average diameter of about 40 nm. Lipid composition of the particles resembles that reported for plasma VLDL, with the exception of a markedly lower cholesterylester content. In 24-hour cultured human hepatocytes, physiological (i.e., portal) concentrations of taurocholic acid (10 to 200 μmol/L) suppressed [3H]triacylglycerol secretion dose dependently. The degree of inhibition highly correlated (r = .87, P < .01) with taurocholic acid content of the cells of different preparations (n = 7). ApoB secretion was inhibited by taurocholic acid to a similar extent as [3H]triacylglycerol secretion (r = .93, P < .01). Lipid composition of secreted VLDL particles did not change during taurocholic acid-induced suppression. No effects on intracellular apoB, [3H]triacylglycerol, triacylglycerol, and cholesterol mass were observed, nor did taurocholic acid affect protein synthesis, albumin secretion, or lactate dehydrogenase (LDH) release. Cellular cholesteryl ester (CHE) mass, however, was markedly reduced. Our results show that bile acids strongly interfere with the assembly or secretion of VLDL particles by human hepatocytes, suggesting a physiological function of the enterohepatic circulation of bile acids in the regulation of postprandial serum lipid levels.
Response of renal nerve activity to high NaCl food intake in dogs with chronic bile duct ligation
Authors: Matsuda T , Morita H , Hosomi H , Okada M
Published: November 2004

Hepatic sensory systems are thought to play an important role in the response of renal nerve activity and natriuresis to oral NaCl load. In this study, responses of renal nerve activity and urinary Na+ and Cl− excretions to a high-NaCl food intake (20 g/kg boiled rice containing 0.4 g/kg NaCl) were examined in sham-operated dogs (n = 12) and dogs with chronic bile duct ligation (CBDL; n = 10). In sham-operated dogs, renal nerve activity gradually decreased and reached minimal value (50% ± 7% of the control value) at 100 minutes after the high-NaCl food intake and remained depressed until 4 hours after the food intake. Of the orally administered sodium and chloride, 27% ± 5% and 23% ± 6% were excreted over the following 4 hours, respectively. In CBDL dogs, the decrease in renal nerve activity induced by the high-NaCl food was completely abolished and only 4% ± 1% of the loaded Na+ and 3% ± 2% of the loaded Cl− were excreted. Furthermore, liver tissue norepinephrine concentration in CBDL dogs decreased to 21% of that of sham-operated dogs. These results suggest that (1) In CBDL dogs, the decrease in renal nerve activity induced by a high-NaCl food is completely abolished, probably because of the impairment of hepatic neural regulation. (2) The lack of renal nerve response may contribute, at least in part, to the abnormalities in body fluid homeostasis in cirrhosis.
Cytokine-induced neutrophil chemoattractant release from hepatocytes is modulated by Kupffer cells
Authors: Mawet E , Shiratori Y , Hikiba Y , Takada H , Yoshida H , Okano K , Komatsu Y , Matsumura M , Niwa Y , Omata M
Published: November 2004

To clarify the role of intercellular communication in the liver during accumulation of neutrophils, the release of cytokine-induced neutrophil chemoattractant (CINC) (interleukin-8 [IL-8] related protein in rodents) by hepatocytes was investigated in the presence of Kupffer cell-conditioned medium in vitro. Kupffer cells were prepared by perfusion of rat liver with collagenase followed by centrifugation on a metrizamide gradient and were cultured in the presence or absence of lipopolysacharide (LPS). The conditioned medium was collected after 24 hours, and rat hepatocytes were cultured in the presence or absence of Kupffer cell-conditioned medium. An amount of CINC in the culture supernatant was measured by western blotting analysis and enzyme-linked immunosorbent assay (ELISA), and expression of its messenger RNA (mRNA) was assessed by the polymerase chain reaction. LPS-stimulated Kupffer cell-conditioned medium enhanced an expression of CINC mRNA in hepatocytes and increased the production of CINC by hepatocytes. Enhanced production of CINC was not shown when the Kupffer cell-conditioned medium was pretreated with heat (56 degrees C, 30 minutes). The production of CINC by hepatocytes in the presence of the LPS-stimulated Kupffer cell-conditioned medium was reduced by an antibody against interleukin 1β (IL-1β), but not by antibodies against tumor necrosis factor α (TNF-α) or LPS. These results suggest that production of CINC by hepatocytes could be regulated by IL-1β released from Kupffer cells, leading to neutrophil accumulation during liver injury, because this protein is a strong chemoattractant for neutrophils.
Overexpression of a p -glycoprotein in hepatocellular carcinomas from woodchuck hepatitis virus-infected woodchucks ( Marmota monax )
Authors: Dunn S E , Hughes C S , LeBlanc G A , Cullen J M
Published: November 2004

The leading cause of human hepatocellular carcinomas (HCCs) is hepatitis B virus (HBV) infection. Woodchucks infected with a closely related hepadnavirus, woodchuck hepatitis virus (WHV), serve as a model for HBV because woodchucks chronically infected with WHV also develop hepatocellular carcinomas. Increased expression of p-glycoprotein (pgp) in human HCCs is a common obstacle in successful cancer chemotherapy. Pgps are encoded by a family of multidrug-resistance (MDR) genes. Livers from uninfected and WHV-infected woodchucks were examined to determine if pgp was expressed in HCCs and if there was a difference in expression between HCCs and nonneoplastic liver. A 170-kd protein was identified by Western blot in HCCs, whereas, constitutive pgp was not detected in normal liver taken from the same animals in 3 of 3 cases. Immunolocalization of the pgp with a panel of monoclonal antibodies revealed intensification of staining in 7 of 20 foci and 12 of 22 HCCs from six animals. Using primers for the human MDR1 gene, a single product was detected by reverse-transcribed polymerase chain reaction (RT-PCR) from HCCs. We have shown an increase in pgp in HCCs compared with normal liver from WHV-infected woodchucks. This is the first example of the induction of a pgp in a naturally hepadnavirus infected rodent system. It suggests the woodchuck can be a useful model for the study of the acquisition of resistance to chemotherapeutic agents in virally induced HCCs.
Intrahepatic hepatitis C RNA levels do not correlate with degree of liver injury in patients with chronic hepatitis C
Authors: McGuinness P H , Bishop G A , Painter D M , Chan R , McCaughan G W
Published: November 2004

The balance between a direct cytopathic effect by hepatitis C virus (HCV) and immune-mediated injury remains unclear. This report aims to test the following hypotheses: (1) that intrahepatic HCV load would correlate with the degree of liver injury; (2) that interferon alfa (IFN-α) would decrease intrahepatic HCV-RNA levels. Liver tissues (n = 56) were obtained from 47 patients with chronic HCV (9 before and after IFN-α therapy). Total RNA was isolated and quantitated for specific HCV RNA by dot-blot polymerase chain reaction (DB-PCR) using a standard curve created from synthetic HCV RNA of known titer to calculate actual RNA levels. A multivariate analysis was undertaken to determine the relationship of intrahepatic HCV-RNA levels with risk factors, length of HCV exposure, and histological injury scores. The confounding effect of HCV genotype was examined by direct sequencing of the NS5b region. Liver HCV RNA ranged from 102 to 3.1 × 107 molecules per microgram total liver RNA. The multiple regression analysis showed no effect of length of HCV exposure, risk factors, degree of bile duct damage, steatosis, or total Scheuer or Knodell score on RNA levels. No significant confounding effect of HCV genotype on the degree of liver injury was observed. However, genotype 1b had a significantly higher mean intrahepatic HCV-RNA load compared with the other genotypes detected. In the 9 patients who received IFN-α, treatment, 7 had no detectable HCV after treatment. This was associated with a significant decrease in intrahepatic HCV-RNA levels (7.57 ± 2.53 × 105 to 1.82 ± 1.80 × 103 molecules per microgram total liver RNA ± SEM, n = 9, P = .0005). These results do not directly support our hypothesis that increased intrahepatic HCV load is associated with more severe liver injury. Intrahepatic viral load appears to be significantly increased in patients with genotype lb. IFN-α treatment does significantly lower intrahepatic HCV load.
The natural course of chronic hepatitis C: A comparison between patients with genotypes 1 and 2 hepatitis C viruses
Authors: Kobayashi M , Tanaka E , Sodeyama T , Urushihara A , Matsumoto A , Kiyosawa K
Published: November 2004

This study was conducted to clarify if the long-term histological outcome among patients with chronic hepatitis C differs according to whether they are infected with genotype 1 or 2 hepatitis C virus (HCV). We examined 140 patients with chronic hepatitis C. The HCV genotype was determined by the enzyme-linked immunosorbent assay (ELISA) based on genotypes 1 and 2 specific recombinant proteins; genotype 1 was found in 100 patients (96 were 1b and 4 were indeterminate) and genotype 2 in 36. The two groups showed no significant difference for any clinical background features. Deterioration of the grade of liver histology during the follow-up period was seen in 68.0 percent of the patients with genotype 1 as compared with 41.7 percent of those with genotype 2 (P < .01). Similarly, the deterioration of the stage of liver histology was more common in the former group than in the latter (63.0 percent and 38.9 percent respectively; P < .05). The mean serum HCV-RNA titer was significantly higher in the patients with genotype 1 than in those with genotype 2 (P < .001), and multivariate analysis showed the titer was one of the independent factors of the deterioration of the stage (P = .0044). This phenomenon may be related in part to the difference in pathogenicity between the two HCV genotypes. In conclusion, our results suggest that more severe progression of chronic hepatitis C is seen in patients showing genotype 1b compared with those with genotype 2.
Admission levels of serum Gc-globulin: Predictive value in fulminant hepatic failure
Authors: Schiødt F V , Bondesen S , Petersen I , Dalhoff K , Ott P , Tygstrup N
Published: November 2004

Gc-globulin scavenges actin released from necrotic hepatocytes to the extracellular space. In 77 patients with fulminant hepatic failure (FHF) (excluding patients treated with liver transplantation), admission levels of serum Gc-globulin and degree of complexing with monomeric actin (complex ratio) were determined to evaluate their predictive values in relation to survival/nonsurvival. Gc-globulin levels were significantly reduced in 47 nonsurvivors, compared with 30 survivors (96 +/- 71 mg/L vs. 169 +/- 101 mg/L, P < .001), whereas the complex ratio in nonsurvivors did not differ significantly from that of survivors. Gc-globulin levels were significantly lower in 59 patients with non-acetaminophen-induced FHF, compared with 18 patients with acetaminophen-induced FHF (P < .01). Using a cutoff level of serum Gc- globulin of 100 mg/L, a lesser value correctly predicted nonsurvival in 79 percent of patients with non-acetaminophen-induced FHF, whereas a higher value predicted survival in 60 percent. In patients with acetaminophen-induced FHF, nonsurvival was correctly predicted in 100 percent of patients and survival in 53 percent. In comparison, the King’s College Hospital (KCH) criteria correctly predicted nonsurvival and survival in 69 percent and 57 percent, respectively, of the same non-acetaminophen-induced FHF patients and in 60 percent and 38 percent, respectively, of the acetaminophen-induced FHF patients. Thus, in our study population, the predictive properties of Gc-globulin were in the same range as the KCH criteria. An advantage of Gc-globulin is that it gives an estimate of the outcome already on admission. Acute liver transplantation should be considered in FHF patients with Gc-globulin less than 100 mg/L.
Inhibition of Kupffer cell functions as an explanation for the hepatoprotective properties of silibinin
Authors: Dehmlow C , Erhard J , de Groot H
Published: November 2004

The flavonoid silibinin, the main compound extracted from the milk thistle Silybum marianum, displays hepatoprotective properties in acute and chronic liver injury. To further elucidate the mechanisms by which it acts, we studied the effects of silibinin on different functions of isolated rat Kupffer cells, namely the formation of superoxide anion radical (02
−), nitric oxide (NO), tumor necrosis factor α (TNF- α), prostaglandin E2 (PGE2), and leukotriene B4 (LTB4). Production of 02
− and NO were inhibited in a dose-dependent manner, with an 50% inhibitory concentration (IC50) value around 80 μmol/L. No effect on TNF-α formation was detected. Opposite effects were found on the cyclooxygenase and 5-lipoxygenase pathway of arachidonic acid metabolism. Whereas no influence on PGE2 formation was observed with silibinin concentrations up to 100 μmol/L, a strong inhibitory effect on LTB4 formation became evident. The IC50- value for inhibiting the formation of this eicosanoid was determined to be 15 μmol/L silibinin. The strong inhibition of LTB4, formation by silibinin was confirmed in experiments with phagocytic cells isolated from human liver.

Hence, while rather high concentrations of silibinin are necessary to diminish free radical formation by activated Kupffer cells, significant inhibition of the 5-lipoxy-genase pathway already occurs at silibinin concentrations which are achieved in vivo. Selective inhibition of leukotriene formation by Kupffer cells can at least partly account for the hepatoprotective properties of silibinin.
Hepatobiliary disposition of valproic acid and valproate glucuronide: Use of a pharmacokinetic model to examine the rate-limiting steps and potential sites of drug interactions
Authors: Booth C L , Pollack G M , Brouwer K L
Published: November 2004

Previous work in this laboratory has suggested that the nonlinear disposition of valproic acid (VPA) in the rat may be due to nonlinear distribution of VPA into the liver. The present study was undertaken to elucidate further the hepatobiliary disposition of VPA. VPA (0.1-2 mmol/L) was incubated with isolated rat hepatocytes in vitro. Uptake of [3H]-VPA was linear from 10 to 50 seconds, with minimal (<7 percent) biotransformation. The initial velocity of VPA uptake varied in proportion with the extracellular concentration and was temperature independent, suggesting that VPA traverses the hepatocyte membrane predominantly by passive diffusion. In separate studies, the hepatobiliary disposition of VPA (20mg) was examined in the isolated perfused rat liver (IPL). A pharmacokinetic model was developed to describe the influence of phenobarbital on the hepatobiliary disposition of VPA and valproate glucuronide (V-G) in the IPL; all processes governing VPA and V-G disposition appeared to be linear. Acute administration of phenobarbital to the liver (1.12 mg) decreased the rate constant for canalicular egress of V-G (0.0489 +/- 0.0266 vs. 0.164 +/- 0.075 min−1). In vivo pretreatment with phenobarbital (75 mg/kg/d x 5 d) before liver isolation decreased the biliary excretion of both VPA (1.06E-04 +/- 0.27E-04 vs. 2.76E-04 +/- 0.45E-04 min−1) and V-G (5.63E- 03 +/- 1.98E-03 vs. 1.74E-02 +/- 0.5E-02 min−1), and increased the apparent volume of distribution of VPA (84.6 +/- 2.2 vs. 72.3 +/- 2.1 mL). In vivo phenobarbital pretreatment a changed V-G excretion from a formation to an elimination rate-limited process. These results are consistent with phenobarbital-associated impairment of canalicular egress of some organic anions. This work further supports the utility of pharmacokinetic modeling in: (1) determining the rate-limiting steps in hepatobiliary drug disposition and (2) identifying sites of drug interactions within the hepatobiliary system that may not be evident based on conventional mass-balance analysis.
Synthesis of insulinlike growth factor binding proteins and of the acid-labile subunit in primary cultures of rat hepatocytes, of Kupffer cells, and in cocultures: Regulation by insulin, insulinlike growth factor, and growth hormone
Authors: Scharf J , Ramadori G , Braulke T , Hartmann H
Published: November 2004

The adult liver is the main source of circulating insulinlike growth factors (IGFs) and their serum binding proteins (IGFBPs) including the acid-labile subunit (ALS), a component of the ternary binding protein complex. Within the liver, the biosynthesis of individual proteins has been attributed to different cell populations, e.g., that of ALS to hepatocytes and that of IGFBP-3 to nonparenchymal cells. Ligand and immunoblotting as well as Northern blotting analyses were used to study synthesis of IGFBPs and their hormonal regulation in cultured adult rat hepatocytes, Kupffer cells (KCs), and cocultures. In hepatocytes, synthesis of IGFBP-1, -2, and -4 was observed; insulin and IGF-I decreased that of IGFBP-1, and -2 while increasing that of IGFBP-4. KCs synthesized IGFBP-2, and -3, insulin and IGF-I showing no effect. In cocultures, however, synthesis of IGFBP-3 was stimulated by insulin and IGF-I. By immunocytochemistry IGFBP-3 biosynthesis was localized to KCs exclusively. When pore membranes were used for separation of hepatocytes and KCs in coculture, this insulin-stimulatory action on IGFBP-3 synthesis was preserved. Growth hormone (GH) did not affect biosynthesis of IGFBPs. Expression of ALS was localized in hepatocytes only. Insulin, IGF-I, and GH increased ALS expression. It can be concluded that biosynthesis of individual IGFBPs and of ALS are compartmentalized in adult rat liver and are distinctly regulated by insulin, IGF-I, and GH. The insulin-dependent stimulation of IGFBP-3 synthesis in KCs appears to require a diffusable mediator derived from hepatocytes.
The role of a purinergic P2z receptor in calcium-dependent cell killing of isolated rat hepatocytes by extracellular adenosine triphosphate
Authors: Zoetewij J P , van de Water B , de Bont H J , Nagelkerke J F
Published: November 2004

Extracellular adenosine triphosphate (ATPo) (0.4 mmol/L), a P2-purinergic receptor agonist, induces cytolysis in several cell types including isolated rat hepatocytes. In this study, we investigated the P2-receptor involved in ATPo-induced, Ca2+-dependent cytotoxicity in hepatocytes. Pretreatment of hepatocytes with oxidized ATP, a P2z-receptor antagonist, or complexation of ATP4− (the agonist for the P2z-receptor) with an excess of Mg2+, prevented ATPo-induced cell death. Both protective treatments also prevented the development of a sustained high intracellular Ca2+ concentration as well as the subsequent accumulation of inorganic phosphate (Pi). The P2z-receptor agonist 3′-O-’(4-benzoylbenzoyl)-ATP (BzATP) was twofold more potent than ATP in eliciting cytolysis, which was preceded by a sustained high intracellular Ca2+ concentration; pretreatment with oxidized ATP prevented both the increase in the intracellular Ca2+ concentration and cell death. Prevention of ATPo-induced cell death, as well as the increases in the intracellular Ca2+ concentration and inorganic phosphate (Pi) was also achieved by decreasing the pHo to 6.9. Together the findings indicate that Ca2+-dependent cell killing by extracellular ATP in hepatocytes is mediated by a P2z-receptor. The cytolytic effects correlated specifically with a secondary “late” increase in the intracellular Ca2+ concentration.
Expression of Immunoreactive Matrix Metalloproteinases and Tissue Inhibitors of Matrix Metalloproteinases in Human Normal Livers and Primary Liver Tumors
Authors: Terada T , Okada Y , Nakanuma Y
Published: November 2004

Matrix metalloproteinases (MMPs) play an important role in cancer cell invasion by degrading extracellular matrix proteins. However, little is known about the

in situ

expression of MMP in human normal livers and primary liver tumors. In this study, we therefore examined the

in situ

expression of immunoreactive MMP and tissue inhibitors of MMP (TIMP) in 10 normal livers, 11 surgically resected intrahepatic cholangiocarcinomas (CCs), and 6 surgically resected hepatocellular carcinomas (HCCs). In normal livers, MMP and TIMP were infrequently and faintly expressed in bile ducts, but were not expressed in hepatocytes. In the 11 CCs, MMP–1, MMP–2, MMP3, MMP–9, TIMP–1, and TIMP–2 were expressed in tumor cells and/or tumor stroma in 11 (100%), 5 (45%), 8 (73%), 3 (27%), 9 (82%), and 9 (82%), respectively. The expression of MMP and TIMP in tumor cells was located in the cytoplasm with a diffuse or granular pattern; that in the tumor stroma was situated in fibroblasts, leukocytes, and extracellular matrix. Their expression was stronger in CC cases with severe invasion than in CC cases with mild invasion. In contrast, MMP and TIMP were not expressed in any cases of HCC. These results show that intrahepatic bile duct cells may neoexpress or overexpress MMP and TIMP after malignant transformation but that hepatocytes do not, and suggest that MMP and TIMP play an important role in CC cell invasion by degrading extracellular matrix proteins.
Biochemical Epidemiology of Gallbladder Cancer
Authors: Strom B L , Soloway R D , Rios-Dalenz J , Rodriguez-Martinez H A , West S L , Kinman J L , Crowther R S , Taylor D , Polansky M , Berlin J A
Published: November 2004

To evaluate the

a priori

hypotheses that an increased level of glyco and tauro lithocholic acid, perhaps because of a decreased capacity for hepatic sulfation, contributed to the biochemical epidemiology of gallbladder cancer, a case–control study was undertaken at four hospitals in La Paz, Bolivia, and at one hospital in Mexico City, Mexico. Eighty–four cases with newly diagnosed histologically confirmed gallbladder cancer were compared with 264 controls with cholelithiasis or choledocholithiasis in the absence of cancer and with 126 controls with normal biliary tracts. All study subjects were undergoing abdominal surgery. Interview data were collected for all study subjects, as well as blood, bile, and gallstone specimens when feasible. Sera were analyzed for carcinoembryonic antigen, cholesterol concentration, and total bile acids. Bile specimens were analyzed for carcinoembryonic antigen; and for concentration of bile salts; cholesterol; phospholipids; and the glycine and taurine conjugates of cholic, ursodeoxycholic, chenodeoxycholic, deoxycholic, and lithocholates; sulfoglycolithocholate; and sulfotaurolithocholate. Gallstone specimens were analyzed for the percentage of cholesterol content, the percentage of calcium bilirubinate content, and the percentage of calcium carbonate content. Serum bile acids were increased in cases versus the two control groups (median 11.7 nmol/mL vs. 9.3 nmol/mL for stone controls and 8.2 nmol/L for nonstone controls,

P

≤ .02 for each pairwise comparison). Biliary bile acids were markedly decreased in the cases (median 3.98 μmol/mL vs. 33.09 μmol/mL, and 154.0 μmol/L, respectively,

P

≤ .0001 for each comparison), even after excluding those with a serum bilirubin higher than 2.0 mg/dL. Bile cholesterol was lower for the cases as well (median 1.70 μmol/mL vs. 4.90 μmol/mL, and 16.81 μmol/ mL, respectively,

P

≤ .02), as was the concentration of bile phospholipids (median 2.97 μmol/mL vs. 6.26 μmol/mL, and 52.69 μmol/mL,

P

= .1 and .0004, respectively). Contrary to our a priori hypothesis, there was no difference between the cases and either control group in their bile concentrations of lithocholate, the proportion of bile acids which were sulfated, or the concentration of nonsulfated lithocholate. However, the cases had a higher concentration of ursodeoxycholate (UDC) (

P

< .004 for both control groups), especially glycoursodeoxycholate (

P

< .001 for both control groups). A previously published suggestion that gallstone size differed between cases and controls was not confirmed. In conclusion, cases with gallbladder cancer differed from controls with stones and from controls with normal biliary tracts in their serum and bile biochemistries. These findings may be a reflection of the disease process, or may provide useful clues to its pathogenesis.
Liver Function in Early Lyme Disease
Authors: Horowitz H W , Dworkin B , Forseter G , Nadelman R B , Connolly C , Luciano B B , Nowakowski J , O'Brien T A , Calmann M , Wormser G P
Published: November 2004

To evaluate the frequency, pattern, and severity of liver function test abnormalities in patients with Lyme disease associated with erythema migrans (EM), 115 individuals with no other identifiable cause for liver function test abnormalities who presented with EM between July 1990 and September 1993 were prospectively evaluated. For individuals with abnormal liver function tests, common causes of hepatitis, including hepatitis A, B, and C, were excluded. A local control group was used for comparison. Forty–six (40%) patients had at least one liver test abnormality, and 31 (27%) had more than 1 abnormality compared with 19 (19%) and 4 (4%) of controls, respectively (

P

< .01 for each comparison). γ–Glutamyl transpeptidase (28%) and alanine transaminase (ALT) (27%) were the most frequently elevated liver function tests among Lyme disease patients. Anorexia, nausea, or vomiting was reported by 30% of patients, but did not occur more frequently in patients with elevated liver function tests compared with those with normal values. Patients with early disseminated Lyme disease were more likely to have elevated liver function studies (66%) compared with patients with localized disease (34%) (

P

= .002). After antibiotic treatment, elevated liver function tests improved or resolved in most patients. Liver function test abnormalities are common in patients with EM but were mild, most often not associated with symptoms, and improved or resolved by 3 weeks after the onset of antibiotic therapy in most patients.
Fk506 Inhibits Human Lymphocyte Migration and the Production of Lymphocyte Chemotactic Factors in Liver Allograft Recipients
Authors: Adams D H , Liu Q
Published: November 2004

The macroglide immunosuppressant FK506 is effective at preventing and reversing hepatic allograft rejection. The establishment of graft rejection is dependent upon an influx of lymphocytes from the circulation into the graft in response to locally secreted chemotactic factors. Thus, inhibition of lymphocyte migration might be an additional mode of action of FK506 that could block lymphocyte recruitment to rejecting liver allografts. In the present study, we provide evidence to support this hypothesis because we have demonstrated, using

in vitro

migration assays, that FK506 can inhibit the migration of lymphocytes, including CD4+ and CD8+ T–cells, to structurally diverse chemotactic factors that are present during human liver allograft rejection. In addition, FK506 acts on lymphocytes in patients with graft rejection to inhibit migration and to block the secretion of chemotactic factors

in vitro

. Thus, FK506 might reverse established graft rejection by inhibiting lymphocyte recruitment to the graft

in vivo

.
Biosynthesis and Degradation of Hyaluronan by Nonparenchymal Liver Cells During Liver Regeneration
Authors: Vrochides D , Papanikolaou V , Pertoft H , Antoniades A A , Heldin P
Published: November 2004

Hepatic stellate cells (HSC) and endothelial cells of the liver sinusoids synthesize and degrade hyaluronan, respectively. The roles of these cell types in the biosynthesis and degradation of hyaluronan were studied during regeneration following partial hepatectomy. Pure cultures of HSC and liver endothelial cells (LEC) were obtained from regenerating liver at different stages using a Nycodenz gradient followed by discontinuous Percoll gradient. The HSC that established 3 or 4 days after partial hepatectomy synthesized large amounts of hyaluronan when cultured in the presence of fetal calf serum (FCS) or platelet–derived growth factor B–chain homodimer (PDGF)–BB. These cells, as well as LEC, expressed active PDGF β–receptors. Furthermore, the ability of LEC to degrade hyaluronan was decreased at early stages of liver regeneration. The increased synthesis of hyaluronan by HSC and the failure of LEC to catabolize the polysaccharide resulted in elevated hyaluronan concentrations in the blood.
An Algorithm for the Grading of Activity in Chronic Hepatitis C
Authors: Bedossa P , Poynard T
Published: November 2004

Histological activity reflects the global assessment of basic necroinflammatory lesions and is a criterion of major importance in chronic hepatitis C. The aim of this study was to propose and test the accuracy of a simple algorithm that generates a single activity score based on basic pathological features. A panel of 10 pathologists reviewed 363 chronic hepatitis C liver biopsies and graded the activity of hepatitis according to their own experience (reference activity). Then, a consensual algorithm on the grading of activity was established by the 10 experts in a panel discussion. Finally, stepwise discriminant analysis was performed to define which basic features had been intuitively used in the reference activity (statistical activity). To test the accuracy of the algorithm, concordance between the activity defined by the algorithm and the reference activity was assessed. It was compared with concordance between the activity defined by the statistical model and the reference activity. The algorithm proposed by the panel for the grading of activity included piecemeal necrosis and lobular necrosis. Concordance between reference activity and activity defined by the algorithm was substantial (305 cases, 84%, κ = .75). Discriminant analysis showed that piecemeal necrosis, lobular necrosis, and portal inflammation were independently used to grade the activity. Concordance between reference activity and activity defined by the statistical model was substantial (300 cases, 83%, κ = .73), virtually identical to the concordance between reference activity and activity defined by algorithm. This study proposes a simple algorithm for the grading of activity in chronic hepatitis. Its accuracy is as high as that obtained using a statistical approach.
Effects of Dietary Cholesterol on Hepatic Production of Lipids and Lipoproteins in Isolated Hamster Liver
Authors: Chen J , Song W , Redinger R N
Published: November 2004

The effect of 2–week 2% cholesterol vs. chow feeding on regulation of hepatic lipoprotein, lipids and apoprotein (Apo), and biliary lipids production was evaluated by the isolated perfused hamster liver model. Cholesterol feeding did not change very–low–density lipoprotein (VLDL), low–density lipoprotein (LDL), and high–density lipoprotein (HDL) particle size but significantly increased the hepatic production of VLDL–cholesterol fourfold, VLDL–triglyceride two and one–half–fold but not phospholipid in VLDL. It also increased LDL–cholesterol fourfold but not triglyceride or phospholipid in LDL, whereas lipids in HDL remained unchanged. Gradient sodium dodecyl sulfate–polyacrylamide gel electrophesis (SDS–PAGE) and Western blot analysis (density of apoprotein/density of albumin/g liver) indicated that cholesterol feeding enhanced Apo B tenfold, Apo A–I fivefold but not Apo E in VLDL. Apo E and Apo B did not change in LDL. Apo E but not Apo A–I increased (threefold) in HDL by cholesterol feeding. Cholesterol feeding decreased bile salt secretion 28% but increased cholesterol secretion 118% in bile, whereas phospholipid and bile volume remained unchanged. Increased Apo A–I in VLDL suggested that Apo A–I is involved in enhanced hepatic export of cholesterol and triglyceride. Different patterns of lipid and Apos in VLDL and LDL after cholesterol feeding also suggested separate VLDL and LDL export mechanisms. Elevated Apo E but not lipids in HDL after cholesterol feeding suggests that hepatic HDL may function as a carrier of newly synthesized hepatic Apo E into the circulation for transfer to other lipoproteins (chylomicron [CM], CMr) to facilitate hepatic cholesterol uptake and clearance.
Blocking Late Cholesterol Biosynthesis Inhibits the Growth of Transplanted Morris Hepatomas (7288Ctc) in Rats
Authors: Xu G , Salen G , Lea M , Tint G S , Nguyen L B , Batta A K , Chen T S , Shefer S
Published: November 2004

The conversion of 7–dehydrocholesterol to cholesterol is the last reaction in the cholesterol biosynthesis pathway catalyzed by the microsomal enzyme, 7–dehydrocholesterol–delta 7–reductase. We studied whether malignant tumor growth that depends on cholesterol could be slowed by inhibiting late cholesterol biosynthesis. The inhibitor 7–dehydrocholester–delta 7–reductase, BM 15.766 alone, or in combination with 2% cholesterol was fed to 20 male Buffalo rats for 2 weeks immediately after Morris hepatoma 7288CTC was implanted in both flanks. Tumor weights were compared and sterol composition, hepatic hydroxymethyl glutaryl coenzyme A (HMG–CoA) reductase activity, and low– density lipoprotein (LDL) receptor binding in the tumor were correlated with those in the liver. In the plasma of rats treated with BM 15.766, cholesterol levels dropped 75% and the precursor, 7–dehydrocholesterol rose substantially. Tumor weights were 43% less (

P

< .05) than controls (5.9 ± 1.5 g vs. 10.4 ± 2.2 g) with sterol concentrations reduced 25%, and the precursor, 7–dehydrocholesterol, increased to represent 71% of the tumor sterols. Feeding cholesterol with BM 15.766 normalized plasma but only partially restored tumor cholesterol concentrations, which still remained 49% below the hepatomas in the control group. With BM 15.766, hepatic cholesterol decreased 76% and was associated with a marked rise of 7–dehydrocholesterol that could be almost entirely prevented by feeding cholesterol. After the tumor was implanted, hepatic HMG–CoA reductase activity increased 56% and was 8.6 times higher than in the tumor. Enzyme activities were enhanced about 50% in the liver and the tumor after BM 15.766 was administered but decreased 38% below control when cholesterol was added to the diet. Hepatic receptor–mediated LDL binding rose 67% after tumor implantation, and declined to control levels with cholesterol feeding. These results suggest that de novo cholesterol synthesis in Morris hepatoma 7288CTC is much lower than the liver and tumor growth depends on circulating plasma cholesterol. Inhibiting the last step in cholesterol biosynthesis profoundly reduced tissue and plasma cholesterol concentrations and accumulated precursors substantially to slow hepatoma growth. Feeding cholesterol restored liver but not hepatoma cholesterol levels. Thus, inhibiting late cholesterol synthesis hinders growth of rapidly enlarging malignant tumors.
Hepatitis B Virus Mutations in the Pre–S Genome Before and After Liver Transplantatio
Authors: Trautwein C , Schrem H , Tillmann H L , Kubicka S , Walker D , Böker K H , Maschek H J , Pichlmayr R , Manns M P
Published: November 2004

Mutational changes in the pre–S region of hepatitis B virus (HBV) were analyzed in 20 patients who experienced HBV reinfection after orthotopic liver transplantation (OLT). HBV DNA was extracted from patient sera before and after OLT. The pre–S sequence was amplified via polymerase chain reaction, subcloned, sequenced, and analyzed. In 18 of 20 patients, mutational changes were found in the pre–S region pre– or post–OLT; 11 showed point mutations (1–10) and 7 cases major changes (insertions/deletions). For the point mutations, there was no trend in the selection of wild–type (wt) HBV before or after OLT in the pre–S region. Additional HBV reinfection during hepatitis B surface antigen antibody (anti–HBS) administration had no influence on selection pressure in the pre–S region. In contrast, insertions/deletions were more frequently found before OLT. In the 7 patients with deletions/insertions, changes in the hepatocyte attachment site were not seen after OLT. Interestingly, the only patient with changes in a major virus population after OLT had changes in the CCAAT–box of the S–promoter. As shown by gel shift analysis, this mutation was associated with loss of specific binding to this element and thus probably led to dysregulation of S–gene transcription. Major changes in the pre–S genome are mainly seen before OLT, and HBV reinfection does occur with the intact hepatocyte attachment sites after OLT. Anti–HBs (hepatitis B immune globulin [HBIg]) creates no selection pressure on the pre–S region. The mutation in the CCAAT–box of the S–promoter potentially leads to its dysregulation and may be associated with the occurrence of fibrosing cholestatic hepatitis after OLT.