However, a clinical study revealed that leptin administration achieved only modest body weight and fat loss in obese patients with hyperleptinemia, advocating the requirement of a leptin sensitizer for enhancing the efficacy of leptin therapy.4, 33, 37 Our data suggest that retinoids might act as a promising leptin sensitizer by restoring hepatic LEPR expression. Future study should examine the effect of retinoids in db/db mice, which genetically lack only LEPRb but express other LEPR isoforms that function in peripheral tissues

as well as the liver. However, the relatively highly phosphorylated STAT3 levels in the HFHFr and ATRA + HFHFr groups despite reduced JAK2 phosphorylation KU-57788 mouse and LEPR levels suggest additional mechanisms underlying leptin resistance. Since no difference in SOCS3 expression was observed in the present study, other negative regulators might be involved in this discordance.

Microarray data demonstrated that the expression of SH2 domain-containing mTOR inhibitor protein tyrosine phosphatase-2, the hepatocyte-specific deletion of which leads to enhanced and prolonged STAT3 phosphorylation,35 was decreased in the HFHFr and ATRA + HFHFr groups compared with the control group. qPCR also confirmed 1.7- and 2.9-fold down-regulation of SH2 domain-containing protein tyrosine phosphatase-2 in the HFHFr and ATRA + HFHFr groups, respectively (both P < 0.05, compared to the control). Further investigation is necessary to elucidate additional involvement of negative regulators in hepatic leptin resistance. STAT3 has recently emerged as an important regulator for hepatic gluconeogenesis given its activity to suppress the expression of PPARγ-coactivator 1α, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase 1.13-15 Mice genetically deficient in hepatic STAT3 activation exhibit severe steatosis, hyperinsulinemia, and glucose intolerance when fed a choline-deficient diet.13, 14 In addition to STAT3, the gene encoding IGFBP2 is a target of the leptin signaling pathway in the liver, and plays an important role in leptin's antidiabetic

activity.29 Mice with hepatic RARα deficiency exhibit steatohepatitis associated with reduced expression of IGF1, which reduces blood glucose level by acting as an anabolic and metabolic hormone.24, 25 Studies have proposed click here that IGFBP2 enhances the stability of IGF138; although the expression of IGF1 was not changed in the present study (data not shown), it is still possible that the enhancing effect of IGFBP2 contributes to ATRA action. Interestingly, IGFBP2 administration has been found to mitigate glucose intolerance and hyperinsulinemia not only in ob/ob mice, but also in leptin-resistant mice.29 Taken together, these present and previous findings suggest that either or both STAT3 and IGFBP2 may play a role in retinoid action, at least in part. Consumption of high-fructose-containing foods is reported to be a risk factor for the development of NAFLD.

Altogether, this suggests that simvastatin, especially if given prior to LPS, might have a hepatoprotective activity in endotoxemia.

http://www.selleckchem.com/products/c646.html LPS increased liver nitro-oxidative stress, shown by an increase in nitrotyrosinated proteins. Simvastatin abrogated the increase in nitrotyrosinated proteins when given prior to or after LPS (Fig. 5A). This could not be explained by a reduction in the iNOS expression, suggesting that simvastatin attenuated nitrosative stress by reducing the generation of reactive oxygen species. Indeed, the increase in liver 4-hydorxynonenal (4-HNE) immunostaining (as a marker of oxidative stress) induced by LPS was blunted by simvastatin treatment, given before or after LPS (Fig. 5B). This study shows that LPS administration induces microvascular dysfunction in rat livers, manifested by increased intrahepatic resistance and by decreased vasodilatory response of the liver circulation to acetylcholine, the hallmark of endothelial dysfunction. This microvascular dysfunction was fully developed 24 hours after LPS challenge. We further demonstrate here that prophylactic simvastatin, a drug that has been shown to correct both systemic and hepatic endothelial dysfunction,24, 25 prevents the development

of microvascular Selleck SAHA HDAC dysfunction and attenuates liver inflammation and liver injury induced by endotoxemia. These findings suggest that the potential of statins for the prevention of liver injury during sepsis should be further explored. selleck inhibitor The occurrence of impaired organ perfusion is the key point for prognostic changes of patients with sepsis.2 In vitro, ex vivo, and in vivo studies have clearly demonstrated that endothelial dysfunction occurs at the level of microcirculation of several organs, i.e., heart, lung, brain, kidney, similar to what occurs at the

level of conductance vessels.4 Our study exhaustively explored endothelial function at hepatic microcirculation in a model of endotoxemia. Our model of isolated liver perfusion allows evaluating specifically the changes occurring at the liver microcirculation, without the interference of the well-described events occurring upstream of the liver, at the systemic and splanchnic circulation (decreased systemic and splanchnic resistance and increased cardiac output30). We demonstrate the presence of sinusoidal endothelial dysfunction after LPS, which may be determinant to explain the decrease in liver blood flow after LPS challenge described by other authors.31 From a molecular point of view previous reports have shown that, similar to nonhepatic endothelial cells, sinusoidal endothelial cells exposed to LPS exhibit decreased eNOS activation through decreased phosphorylation at Ser1176.12 The present study shows that this also occurs in a complex in vivo model, where LPS administration was associated with decreased liver Ser1176 eNOS phosphorylation.

In contrast to naïve T cells, which require high levels of both class I and II MHC-antigen complexes and costimulatory CD80/CD86 molecules for activation, iTreg can be fully activated by semimature DCs (smDCs) expressing low levels of both MHC-antigen complexes and costimulatory CD80/CD86.4 The state of maturation of the DCs is of particular interest, since smDCs in mice induced optimal antigen-specific expansion of CD4+CD25+FOXP3+ Treg cells in vitro.10 Presentation of peptide antigen with submaximal costimulation

appears to be essential for activating Treg function in animal models of autoimmunity.11 Type 2 Everolimus AIH is ideally suited to explore the role of iTreg in pathogenesis and their potential therapeutic use. In contrast to type 1

AIH, in which the hepatic autoantigens are poorly defined,3 the autoantigenic epitopes for B, CD4, and CD8 T cells in type 2 AIH are located on cytochrome P450IID6 (CYP2D6).2 The immunodominant autoantigenic B cell epitope is CYP2D6193-212, but additional minor epitopes have also been defined. Epitopes CYP2D6193-212, CYP2D6217-260, and CYP2D6305-348 are recognized by B, CD4, and CD8 T cells. In addition, type 2 AIH is strongly associated with two class II HLA-DR alleles: HLA-DRB1*0701 (DR7) and HLA-DRB1*0301 (DR3), which allows selection of patients with and without these alleles for studies.2 At the time of diagnosis, both the quantity and function of CD4+CD25+FoxP3+ iTreg cells in peripheral AZD6244 supplier blood are deficient in patients with type 2 AIH.12, selleck kinase inhibitor 13 However, successful therapy with corticosteroids and/or azathioprine partially restored the circulating numbers and functions of iTreg,12, 13 indicating that reduction of inflammatory disease activity and deleterious effector T cell functions facilitated iTreg function. In children with type 2 AIH, the quantities

of iTreg were significantly inversely correlated with disease severity as well as with titers of anti–soluble liver antigen (SLA) and anti-LKM1 autoantibodies.13 While the inverse correlation with autoantibody titers has been interpreted as evidence of a pathogenetic role for autoantibodies, a plausible alternative explanation is that the paucity of functional iTreg permitted unregulated CD4 Th cytokine stimulation of antibody secretion. iTreg isolated from peripheral blood mononuclear cells (PBMCs) of afflicted children were unable to inhibit secretion of interferon (IFN)γ by CD4 or CD8 T cells.12, 13 Evidence that polyclonal expansion of iTreg from PBMCs could partially overcome these deficiencies underscored the importance of iTreg in the pathogenesis of type 2 AIH and their potential therapeutic use.14 The study of Longhi et al.

[23] To obtain mitral inflow pattern, pulsed-wave Doppler echocardiography recordings were obtained from a sample volume positioned at the tips of the mitral valves parallel to

PF-02341066 chemical structure inflow during diastole at end-expiration. The following parameters were measured: isovolumetric relaxation time (IVRT); peak early filling (E) and its deceleration time (DT); atrial filling peak (A); and the early diastolic mitral inflow velocity/late diastolic (E/A) ratio. E/A ratio was corrected for age. Recordings of mitral inflow with Valsalva maneuver were generally not performed. TDI measurements were sampled at the level of the mitral annulus over the septal wall. Peak early diastolic annular velocity (e′) was measured at the septal and lateral mitral annular sites.[21] Values of e′ measured at both sites were averaged. The combined E/e’ ratio was also calculated. All recordings were performed at a sweep speed of 50-100 mm/sec and averaged over three consecutive cardiac cycles. All echocardiograms

were interpreted by J.N., who had no knowledge of the clinical and laboratory data. LVDD was defined and classified according to ASE guidelines.[21] LVDD included the following categories: grade 1: e’ <8 cm/sec, E/e' ratio <8, E/A ratio <0.8, and DT >200 ms; grade 2: e’ <8 cm/sec, E/e' ratio 9-15, E/A ratio 0.8-1.5, and DT 160-200 ms; and grade 3: e' <8 cm/sec, E/e' ratio >15, E/A ratio >2, and DT <160 ms. Normal ventricular function at rest was defined by an LVEF >50% and without LVDD (e’ ≥8 cm/s, E/e’ ratio selleck chemicals llc <8, and E/A ratio >1). Effective arterial blood volume was assessed by measuring plasma concentration of PRA. The criteria used to define decreased arterial this website blood volume were derived from those used in previous studies as an increase in PRA to a level >4 ng/mL/hour.[20] Results are reported as frequencies or means ± standard deviation (SD) plus 95% confidence

interval (CI) of the mean. The Student t, Mann-Witney’s, or chi-squared tests were used to compare continuous or categorical variables. For comparisons of multiple independent groups, Kruskal-Wallis’ test was used, followed by Mann-Withney’s test. Univariate analyses were used to identify variables associated with development of type 1 HRS as well as with survival. Cox’s proportional hazards method was used to assess the prognostic value of these variables. Accuracy of each independent predictive factor of survival was assessed by receiver operating characteristic curves. Kaplan-Meier’s analysis was used to estimate survival, and probability curves were compared by log-rank test. A P value <0.025 was considered statistically significant for comparisons of multiple groups. All statistical analyses were performed using SPSS 15.0 software (SPSS, Inc., Chicago, IL). The investigation included 80 patients. At rest, all had a normal ejection fraction (>50%). Forty-three patients had normal LV diastolic function, 19 had grade 1 LVDD, and 18 had grade 2 LVDD.

The authors stated that they had no interests which might be perceived as posing a conflict or bias. “
“Haemophilia A (HA) is an EPZ015666 purchase X-linked recessive bleeding disorder, caused by a wide variety of mutations in the factor VIII (F8) gene, leading to deficiency in the activity of coagulation FVIII. These mutations can affect all the F8 exons from the initiation codon to the termination codon, however, only few molecular changes in the promoter region of the F8 gene were reported so far. Here, we describe six nucleotide variations (c.-51G>A, c.-218T>C, c.-219C>T, c.-219delC, c.-221T>A

and c.-664G>A) detected in the F8 promoter and their correlation with clinical phenotype of the patients. Potential role of these mutations in HA was also assessed. Causality was demonstrated with transient transfection experiments using luciferase reporter gene plasmids and computational analysis. Two molecular changes (c.-51G>A and c.-664G>A) did not seem to affect the promoter function of the F8 gene whereas c.-218T>C, c.-219C>T, c.-219delC, c.-221T>A mutations had an impact Selleck BGJ398 on the F8 promoter function and were responsible for HA. Furthermore, these mutations were associated with resistance to 1-deamino-8-d-argininevasopressin (desmopressin) therapy when

they were causative. When molecular variation was detected in F8 promoter, we propose to use prediction software and to verify predictions by reporter gene analysis. If the mutation is causative, it will be probably associated with a lack of therapeutic response to desmopressin selleck chemicals llc and this clinical implication should be considered by clinicians. “
“Hereditary haemophilia A is an X-linked bleeding disorder caused by mutations in the coagulation factor VIII gene (FVIII abbreviates protein, gene symbol F8). The mutation spectrum has been reported in various populations

but not in Pakistan. The aims of this study were to (i) characterize F8 mutations in a large haemophilia A cohort from Pakistan and to (ii) investigate whether in vitro thrombin generation (TG) differs according to mutation type (null compared with missense) in severe haemophilia A. One hundred individuals diagnosed with haemophilia A and 100 healthy controls were recruited in Pakistan. Phenotypic measurements were re-evaulated in Cardiff; the essential regions of F8 were screened for the causative defect. A diagnosis of haemophilia A was confirmed for 92 individuals, 7 were found to have haemophilia B and 1 did not have haemophilia. The F8 defects were characterized for 80 of the 92 haemophilia A individuals and comprised point mutations, inversions (intron 22 and intron 1) and frameshifts. Point mutations (41%) were the most frequent, followed by the intron 22 inversion (20%). Thirty novel variants were identified.

g. model ψ(area + AS) p(.) for S. salamandra]. In addition to these models, we set up candidate models with combinations of predictor variables. The first model describing the terrestrial habitat included the predictors ‘area’, ‘forest’, ‘slope’ and ‘PCA climate’ [model ψ(habitat) p(.)]. The second model, which was only used for the S. salamandra data, included the predictors ‘slope’, ‘stream bank slope’, ‘pools’ and ‘hides’ to assess PLX-4720 cost the effect of stream parameters on the species’ occupancy probability [model ψ(stream) p(.)]. Two more candidate models were obtained by adding the presence of the other species to the two multi-variable models.

Based on the results of the a priori models for each species, we additionally combined the predictors of the QAIC best ranked models into

four new a posteriori candidate models with combination of two or three predictor variables (see Supporting Information Tables S1 and S2). Because there was a model selection uncertainty, we used model learn more averaging techniques for parameter estimation (Burnham & Anderson, 2002). For model averaging, models with ΔQAIC >7 were dropped from the set of candidate models for each species and Akaike weights were recalculated for the set of models with ΔQAIC ≤7. Based on the new Akaike weights, model averaging was performed for all predictor variables in models that were retained in order to assess their effect on the species’ occupancy probability. During field surveys (mean duration per visit ± standard deviation was 53.8 ± 14.5 min for Zug; 46.4 ± 14.0 min for Nidwalden), we detected Salamandra salamandra at 16/23 of

the sampling sites in the contact zone in Zug and 13/19 in Nidwalden. Salamandra atra was found at 5/23 of the sampling sites in Zug compared with 17/19 in Nidwalden. Co-occurrence of the salamanders was found at 3/23 sampling site in Zug and at 12/19 sites in Nidwalden. Table 2 shows the top-ranking models (based on QAIC) for both salamander species. For both species, top-ranking models always included ecological predictor variables and were better than the intercept-only selleck products models (i.e. null models). The analysis revealed that the model including ‘slope’ and ‘pools’ as predictors for the fire salamander’s occupancy probability was best supported by the data. Model averaging showed that only the 95% confidence interval of ‘slope’ did not include zero (Table 3). The positive effect of the slope of the sampling sites on the occupancy probability is shown in Fig. 2. The confidence intervals of all other predictor variables included zero. In particular, while the estimated effect of alpine salamander on fire salamander occupancy was negative, the 95% confidence interval included zero (Table 3). The observed data for S. atra were best explained by the model with the predictor variable ‘area’. In this model, we estimated a four times lower occupancy rate for S. atra in Zug (0.22, se 0.

“
“Abbreviations: HCC, hepatocellular carcinoma; HRS, hepatorenal syndrome; HVPG, hepatic venous pressure gradient; NSBB, nonselective beta-blocker; RCT, randomized controlled trial; SBP, spontaneous bacterial peritonitis. Patients with cirrhosis are at risk for developing complications that can negatively impact their survival.1 These complications include the development of hepatocellular carcinoma (HCC), sepsis, renal failure, and gastrointestinal bleeding, mainly variceal. The risk of bleeding is mainly related to the development of varices from portal hypertension. Bleeding from varices, whether

Ipilimumab mouse esophageal or gastric, is associated with a mortality risk of 40% at 1 year.2 Twenty-nine years ago, a randomized controlled trial (RCT) from France involving 74 patients with cirrhosis with a history of gastrointestinal bleeding showed that propranolol, a nonselective beta-blocker (NSBB), significantly reduced the risk of rebleeding from esophageal varices.3 Since then, 615 articles have been published in the English literature on the use of propranolol or nadolol (the other NSBB) in cirrhosis, both for primary and secondary prophylaxis. In fact, NSBBs have become one of the most effective preventative therapies in patients with cirrhosis against variceal bleeding.4 The advantage of using NSBBs, however,

must be weighed against the risks associated with their chronic use. NSBBs are contraindicated in patients with refractory asthma, respiratory failure, advanced atrio-ventricular block, and severe arterial hypotension. In order to improve Selleck Metformin the risk/benefit ratio, administration of beta-blockers is recommended only in patients with a substantial risk of bleeding such as those patients with medium or large varices or patients with small esophageal varices who have Child-Pugh class C cirrhosis.5,

6 If possible, hepatic venous pressure gradient (HVPG) should be measured before and 1-2 months after NSBB administration to identify responders (those this website with a final HVPG < 12 mm Hg or those who show a decrease of ≥20% in HVPG versus the pretreatment value) who are most likely to benefit from NSBB prophylaxis. Nonresponders should discontinue therapy so to prevent the development of side effects when their chances of any therapeutic benefits are small.7 In the ensuing 29 years since the original description of the effectiveness of propranolol in preventing variceal bleeding, many other drugs such as angiotensin receptor antagonists, selective beta-blockers, nitrates, alpha-receptor antagonists, and endothelin receptor antagonists, to name a few, have been investigated for their ability to decrease portal pressures. None of these agents has shown a more favorable profile than NSBBs in the prophylaxis against variceal bleeding.

06). The demographic characteristics of the patients in the confirmation study were comparable to those of the patients in the principal study (Table 1), even though there was a difference in selective digestive tract decontamination, type of intravenous antibiotic prophylaxis, and immunosuppressive therapy. The frequencies Apoptosis Compound Library for the various

SNPs of the recipients were similar compared to the principal group (Supporting Table 2). The cumulative incidence of CSI within the first year was significantly lower (22% [36/167] versus 41% [59/143], P = 0.007) and the percentage of transplanted donor livers with an MBL-deficient genotype was significantly lower in this confirmation group compared to the principal study (13% [22/167] versus 22% [31/143], P = 0.05; Supporting Table 2). Nevertheless, the lectin pathway gene profile of the donor liver in this confirmation group showed a similar significant association with the cumulative incidence of CSI (56% [5/9]

with three variants, 26% [15/57] with two variants, 15% [12/81] with one variant, and 20% [4/20] when genetic variants were absent, Ku 0059436 log-rank = 8.2; P = 0.04). Furthermore, the effect of the donor-recipient genotypic match was also confirmed. MBL mismatch, i.e., a sufficient recipient and an insufficient donor liver, conferred a significantly increased risk for developing clinically significant infection compared to the other MBL combinations (40% [8/20] versus 19% [28/147],

P = 0.03), whereas again a lower risk of CSI was associated with absence of the minor T-allele in FCN2 SNP rs17549193 (10% [5/50] versus 27% [31/117], P < 0.03) and the absence of homozygosity for the major A-allele in MASP2 SNP rs12711521 (9% [2/23] versus 24% [34/144], P = 0.11) in both recipient and donor. In the selleck chemical univariate regression models, a significant association was found for the separate donor gene polymorphisms with CSI of the combined data from both cohorts, in particular for MBL2 (XA/O and O/O) and FCN2 (rs17549193), and less so for MASP2 (rs12711521) (Table 3). In addition, the lectin pathway gene profile of the donor liver showed a significant stepwise association with CSI. In the presence of three variants, 67% CSI was found; 38% CSI was found in the case of two variants, 23% CSI in the case of one variant, and 19% CSI was found when genetic variants in the lectin pathway were absent (P < 0.001). The only other factors associated with the infection risk were found to be male sex of the donor and recipient, the antibiotic prophylactic regimen used, and acute cellular rejection.

2 were detectable in all analyzed cell lines (see Supporting Table 1). However, these data do not sufficiently explain the distinct decrease of AKAP12 protein expression observed in this study. As a possible suppressive mechanism, we investigated the DNA methylation of promoter-related CpG islands of both AKAP12 isoforms in NL, CL, DN, and HCC samples by quantitative MassARRAY analysis (Fig. 1). In tumor samples, hypermethylation was detected

in the AKAP12α promoter (Fig. 5A,B), but not in the AKAP12β promoter (Fig. 5C,D). Methylation analysis of the AKAP12β promoter showed a methylation value higher than 10% only for one HCC sample. For the AKAP12α promoter, a mean methylation of 12% for NL and CL, 15% for DN, and of 30% for Proteasome inhibitor HCC was observed. As high amounts of fibroblasts, infiltrating immune cells, and other nonparenchymal cells may inflict on the genuine methylation status of hepatocytes in CL, microdissection of

hepatocytes was performed. However, the methylation values of CL specimens after microdissection (18%) did not significantly differ from undissected samples of the same tissues. Elevated PD0325901 DNA methylation levels of the AKAP12α promoter were also detected in HCC cell lines. This analysis revealed DNA methylation of 96% (AKN1), 42% (HuH7), 41% (Hep3B), 24% (HepG2), and 20% (PLC/PRF/5) (Fig. 5A,B). Methylation analysis of the AKAP12β promoter in cell lines showed methylation values lower than 1% (Fig. 5C,D). Hypermethylation of the AKAP12α promoter was confirmed by an independent method (combined bisulfite restriction check details analysis; see Supporting Fig. 2). To verify the functional relationship between promoter hypermethylation and loss of AKAP12 gene expression, methylation and mRNA expression levels of both isoforms were compared before and after treatment with 5-aza-dC in cell lines AKN1, HepG2, and HuH7. Isoform-specific mRNA expression of AKAP12 differed between untreated hepatic cell lines and PHH but confirmed protein data (Fig. 3B; Fig. 6A). The 5-aza-dC treatment resulted in a decrease in AKAP12α promoter methylation in the highly methylated AKN1

cell line (Fig. 6B), accompanied by a strong increase in AKAP12α mRNA expression (Fig. 6C), demonstrating a relationship between AKAP12α expression and methylation of its promoter. In HepG2 and HuH7 cells, which showed lower methylation levels than AKN1, demethylation as well as re-expression of 5-aza-dC was moderate. Similarly, only a marginal increase in expression was detected for isoform β with its unmethylated promoter (Fig. 6B,C). Data were confirmed in two independent experiments (see Supporting Table 6). Although we have demonstrated that silencing of AKAP12 is associated with DNA hypermethylation in HCC, promoter methylation does not explain the loss of expression in earlier stages of hepatocarcinogenesis. Thus, we postulated that a posttranscriptional mechanism may cause silencing in CL and DN.

On the other hand, 11 of 14 rats in the retired breeder group fed CDE had these tumors. The reason for the low number of such tumors in the younger rats is not clear, but could be due to sampling error or the fact that rats receiving CDE die at an earlier age than the controls or retired breeders fed CDE and thus could be dying before the interstitial cell tumors develop. Other check details cancers found in single

rats (Supporting Information Table 2, Supporting Fig. 2B-F) included leukemia, lung adenocarcinomas, renal cell carcinoma, mucinous carcinomatosis of the peritoneum, transitional cell carcinoma of the bladder, and an osteogenic sarcoma. These tumors are also found characteristically in aged Fischer 344 rats25 and did not show any clear association with CDE feeding.

For example, we found two leukemias in the control groups and one in the experimental. The incidence of leukemia here was lower than what has been reported in the literature, but we found that a number of both control and experimental rats showed extramedullary hematopoiesis in the liver; that condition could have been reported as leukemia in other studies. Localization of EpCAM, HNF6, and C-Met were done to determine expression in oval cells, cholangiofibrosis (CF), and CAA (Supporting Information Table 3, Supporting Fig. 5). EpCAM was present in normal ducts, oval cells, epithelial cells in CF, and CAA, but not in normal or reactive hepatocytes, MG-132 in vitro thus showing consistency of expression in biliary cell types. HNF6 was present in oval cells and CF, but unexpectedly not in CAA. C-Met was expressed weakly in normal hepatocytes, but was highly expressed in focal hepatocytes (notably in mitotic hepatocytes) selleck inhibitor in CDE-fed rats, as well as in oval cells, CF, and CAA. The cellular response of rats to a hepatocarcinogenic regimen is age-dependent. When fed five cycles of CDE diet beginning at age 3 weeks, seven of eight rats developed CCA, preceded by florid oval cell proliferation.

In rats fed the CDE diet beginning at 8 weeks of age, the oval cell response was much lower and a CCA developed in only 1 of 15 rats. When rats were fed the diet beginning at 1 year of age, there was minimal oval cell proliferation and no bile duct carcinomas were seen. This result supports the concept that cancers arise from tissue-determined stem cells, and that the number or potential, or both characteristics, of tissue stem cells to respond to carcinogens declines with aging. Unexpectedly, our cyclic CDE-fed rats did not develop either HBs, as predicted by our working hypothesis, or HCCs. In the literature, oval cell proliferation has generally been considered to be a precursor for development of HCC (for an extensive review, see Sell16).