Possible role of nuclear factor erythroid 2-related factor 2 in the progression of human colon precancerous lesions

BACKGROUND

Increased levels of oxidative stress/cell inflammation contribute to colorectal cancer (CRC) onset. Nuclear factor-erythroid 2-related factor 2 (Nrf2) and its controlled growth factor erv1-like (Gfer) gene regulate redox-sensitive and anti-inflammatory mechanisms, respectively, which can contribute to promoting cancer development.

AIM

We evaluated Nrf2 and Gfer RNA expression and Nrf2 protein expression in colon mucosa in order to establish their possible involvement in the early stage of CRC.

METHODS

Forty subjects were enrolled after a histological evaluation of their colon biopsies. They included 20 subjects with a sporadic colorectal adenoma (SpCA group) and 20 without precancerous lesions (controls). Biopsy samples were processed for gene expression analysis and protein expression, using Real-time PCR and immunofluorescence confocal microscopy, respectively.

RESULTS

Nrf2 and Gfer mRNA expression were significantly reduced (p=0.007 and p<0.003, respectively) in SpCA tissues compared to normal mucosa from controls. Furthermore, immunofluorescence analysis confirmed a relevant reduction of Nrf2 in SpCA tissue compared to normal tissue from controls.

CONCLUSIONS

Our data confirm the hypothesis that Nrf2 and Gfer expression may be involved in the initial hits contributing to the multistep process of colon carcinogenesis. Further larger studies are needed to confirm if Nrf2 and Gfer are potential risk/prognostic factors for cancer development.

The role of PIAS3, p-STAT3 and ALR in colorectal cancer: new translational molecular features for an old disease

OBJECTIVE

Human colorectal cancer (CRC) is characterized by a sequence of biological events that determine its induction and progression. Gut microbiota has an important role in this multistep model of carcinogenesis, as well as constitutive activation of Signal Transducer and Activator Factors 3 (p-STAT3) and Protein Inhibitor of Activated STAT3 (PIAS3), which negatively controls STAT3. It has been reported that a liver growth factor, the Augmenter of Liver Regeneration (ALR), an anti-apoptotic, anti-metastatic factor, exerts protective/cell survival and anti-metastatic activities and has been detected highly expressed in neoplastic cells.

PATIENTS AND METHODS

To evaluate, by immunohistochemistry, p-STAT3, PIAS3 and ALR expression in neoplastic human tissues from CRC patients, grouping the data in accordance with the histological alterations (G1, G2 and G3) and metastasis presence. Western blot (WB) analysis of ALR was also determined in neoplastic and surrounding tissues. Finally, cell proliferation (Ki-67) and apoptosis (Bcl-2) were determined.

RESULTS

Colon cancer tissue samples showed: (1) ALR and p-STAT3 strongly over-expression in 100% of G1 tissue samples, reducing in G2 and G3 tissue samples; (2) PIAS3 immunological determination was poorly expressed in G1 tissue samples and highly expressed in the 100% of colorectal tissues from group G2 and G3. Ki-67 progressively increases with the importance of the anatomic-pathological alterations and Bcl-2 resulted higher in G3 tissue samples compared to G1 neoplastic tissues. WB data evidenced, in neoplastic tissues, compared to the tumour-surrounding tissues, ALR over-expressed in G1 neoplastic tissues and down-expressed in G3 neoplastic tissues.

CONCLUSIONS

Our data demonstrate a different dynamism of the investigated factors in relation to the severity of CRC histological findings. We hypothesize that the positive expression of ALR and p-STAT3 in the neoplastic tissue samples from CRC G1 group, associated to the absence of PIAS3, could be useful marker to identify an early stage of the disease. Based on these data and on our previous studies on gut microbiota in precancerous intestinal lesions, we are confident that, after microbial priming, a cascade of molecular events is started. So, the detectable molecules acting in these initial steps should be considered for the study of CRC progression and therapy.

Two-dimensional hybrid perovskites sustaining strong polariton interactions at room temperature

Polaritonic devices exploit the coherent coupling between excitonic and photonic degrees of freedom to perform highly nonlinear operations with low input powers. Most of the current results exploit excitons in epitaxially grown quantum wells and require low-temperature operation, while viable alternatives have yet to be found at room temperature. We show that large single-crystal flakes of two-dimensional layered perovskite are able to sustain strong polariton nonlinearities at room temperature without the need to be embedded in an optical cavity formed by highly reflecting mirrors. In particular, exciton-exciton interaction energies are shown to be spin dependent, remarkably similar to the ones known for inorganic quantum wells at cryogenic temperatures, and more than one order of magnitude larger than alternative room temperature polariton devices reported so far. Because of their easy fabrication, large dipolar oscillator strengths, and strong nonlinearities, these materials pave the way for realization of polariton devices at room temperature.

Clusterin serum level: how does it affect psoriatic patients?

Psoriasis is a chronic inflammatory skin disease with systemic involvement that might predispose to many psoriasis-related comorbidities, such as metabolic syndrome and cardiovascular disorders. Clusterin (Clu), also known as apolipoprotein J (ApoJ), is a highly conserved disulfide-linked heterodimeric glycoprotein implicated in a great variety of physiological and pathophysiological processes including lipid transportation, tissue remodeling, senescence, cell interaction, stress response, inflammation, apoptosis, diabetes mellitus and metabolic syndrome. Serum levels of Clu were assessed in 15 patients with moderate-to-severe psoriasis defined by the presence of a Psoriasis Area and a Severity Index (PASI) value of 10 or more. It was found that the Clu value was significantly higher in patients than in healthy subjects (p <0.001). Our data confirm that the association of psoriatic disease with some comorbidities, especially metabolic and cardiovascular disease, might support the correlation with increased circulating Clu. In particular, it should be pointed out that, according to the recent literature, the Clu could also have a protective role in the comorbidity of psoriasis patients. In addition, it has been published that Clu protects cardiomyocytes against ischemic cell death and is a potential therapeutic agent in the treatment of myocardial infarction; therefore it can be assumed that an artificial enhancement of Clu in the blood could limit the severity of damage also in respect to skin lesions. Although the increase in serum level of Clu was found in all patients with psoriasis, more studies on a larger cohort of patient samples is necessary to confirm the significance of high serum levels of clusterin/ApoJ and to suggest the use of this glycoprotein as an additional new marker in psoriasis pathogenesis. It could be a possibility to improve the prognosis in patients with psoriasis.

Sub-epitopic dissection of HCV E1315-328HRMAWDMMMNWSPT sequence by similarity analysis

Our labs are focused on identifying amino acid sequences having the ability to react specifically with the functional binding site of a complementary antibody. Our epitopic definition is based on the analysis of the similarity level of antigenic amino acid sequences to the host proteome. Here, the similarity profile to the human proteome of an HCV E1 immunodominant epitope, i.e. the HCV E1(315-328)HRMAWDMMMNWSPT sequence, led to i) characterizing the immunoreactive HCV E1 315-328 region as a sequence endowed with a low level of similarity to human proteins; ii) defining 2 contiguous immunodominant linear determinants respectively located at the NH(2) and COOH terminus of the conserved viral antigenic sequence. This study supports the hypothesis that low sequence similarity to the host's proteome modulates the pool of epitopic amino acid sequences in a viral antigen, and appears of potential value in defining immunogenic viral peptide sequences to be used in immunotherapeutic approaches for HCV treatment.

Intestinal permeability in patients with adverse reactions to food

BACKGROUND

An abnormal intestinal permeability could contribute to establish an altered sensitivity to food-allergen.

AIM

To evaluate the intestinal permeability in subjects with adverse reactions to food on allergen-free diet.

SUBJECTS

Twenty-one patients with food allergy and 20 with food hypersensitivity on allergen-free diet were enrolled and divided in four groups according to the seriousness of their referred clinical symptoms when they were on a free diet.

METHODS

Intestinal permeability was evaluated by Lactulose/Mannitol ratio urinary detection determined by anion-exchange chromatography.

RESULTS

Statistically significant different Lactulose/Mannitol ratio was evidenced in subjects with food allergy (p=0.003) or hypersensitivity (p=0.0008) compared to control patients. The correlation between Lactulose/Mannitol ratio and the seriousness of clinical symptoms, by using Spearman test, was statistically significant for food allergy (p=0.0195) and hypersensitivity (p=0.005) patients.

CONCLUSIONS

The present data demonstrate that impaired intestinal permeability, measured in our conditions, is present in all subjects with adverse reactions to food. In addition, for the first time, we report a statistically significant association between the severity of referred clinical symptoms and the increasing of Intestinal Permeability Index. These data reveal that intestinal permeability is not strictly dependent on IgE-mediated processes but could better be related to other mechanisms involved in early food sensitisation, as breast-feeding, or microbial environment that influence the development of oral tolerance in early infancy.

Mammalian augmenter of liver regeneration protein is a sulfhydryl oxidase

BACKGROUND

Augmenter of Liver Regeneration is an important secondary hepatic growth factor. Augmenter of liver regeneration protein has been shown to control mitochondrial gene expression and the lytic activity of liver-resident Natural Killer cells through the levels of interferon-gamma, but the precise enzymatic function of this protein is unknown.

AIMS

To define the enzymatic activity of augmenter of liver regeneration protein. The carboxy terminus of augmenter of liver regeneration protein contains a special CXXC motif characteristic for redox proteins and with faint homologies to the redox-active site of sulfhydryl oxidases. Tests were, therefore, carried out to establish whether isolated augmenter of liver regeneration protein can also function in the formation of sulfur bridges.

METHODS

Purified augmenter of liver regeneration proteins from rat and human were tested in enzyme assays for the ability to introduce disulfide bonds into protein substrates. The isolated proteins were tested for the formation of dimers and the presence of bound FAD was investigated spectroscopically. The function of the conserved CXXC motif was investigated by in vitro mutagenesis experiments and subsequent enzyme assays.

RESULTS

In this study, we demonstrate that rat and human augmenter of liver regeneration protein are flavin-linked sulfhydryl oxidases that catalyze the formation of disulfide bonds in reduced protein substrates. A flavin moiety is firmly but not covalently attached to the protein. In human cell cultures augmenter of liver regeneration protein is expressed in a long and short form that both exist as covalently linked dimers. The active site of the enzyme is associated with a conserved CXXC motif in the carboxy-terminal domain, that is present in the homologous proteins from yeast to humans and also in the human Q6 growth regulator protein. In vitro mutagenesis of one cysteine residue in the CXXC motif results in loss of enzymatic function and the mutated protein no longer binds FAD.

CONCLUSIONS

For the first time, these data assign an enzymatic activity to the important hepatic growth factor augmenter of liver regeneration protein. The finding that augmenter of liver regeneration protein acts as a FAD-linked sulfhydryl oxidase is essential to identify the molecular targets inside liver cells and to elucidate the precise role of mammalian augmenter of liver regeneration protein in hepatic cell growth, liver disease and regeneration.

The augmenter of liver regeneration induces mitochondrial gene expression in rat liver and enhances oxidative phosphorylation capacity of liver mitochondria

BACKGROUND

The mammalian augmenter of liver regeneration gene encodes a protein involved in the unique process of liver regeneration. The augmenter of liver regeneration respective protein stimulates hepatocyte proliferation in hepatectomized rats and inhibits cytotoxic activity of liver-derived Natural Killer cells from intact rats. Augmenter of liver regeneration protein shares homology with a Saccharomyces Cerevisiae protein essential for the viability, oxidative phosphorylation and cell-division cycle.

AIMS

To demonstrate if augmenter of liver regeneration protein, like the homologous in the yeast, plays a role in the regulation of biogenesis of mitochondria.

METHODS

Augmenter of liver regeneration protein was injected in intact rats and, in the hepatic tissue, the expression of two genes located in two different regions of the mitochondrial genome, mitochondrial ATPase 6/8, and ND1 subunit, and of a nuclear gene, mitochondrial Transcription Factor A, were considered. In addition, cytochrome content and oxidative phosphorylation capacity of liver-derived mitochondria were evaluated.

RESULTS

The augmenter of liver regeneration protein administration induces an increase in the mitochondrial gene expression and enhances cytochrome content and oxidative phosphorylation capacity of liver-derived mitochondria.

CONCLUSIONS

The present data demonstrate a comparable role in the regulation of mitochondria biogenesis in the eukaryotic cell like the yeast protein. This phenomenon could be part of the complex mechanism through which augmenter of liver regeneration regulates hepatocyte proliferation.

Molecular mechanisms of augmenter of liver regeneration as immunoregulator: its effect on interferon-gamma expression in rat liver

BACKGROUND

We have shown that the administration of exogenous Augmenter of Liver Regeneration protein in intact rats i) regulates mitochondrial gene expression by inducing the transcription and translation of the nuclear-encoded mitochondrial transcription factor A, and ii) inhibits the lytic activity of liver-resident Natural Killer cells.

AIMS

The present investigation was carried out to study the effect, in intact rats, of exogenous administration of Augmenter of Liver Regeneration protein on Interferon-gamma, a cytokine produced by activated Natural Killer cells and known to control the expression of mitochondrial transcription factor A, a nuclear gene responsible for mitochondrial metabolism.

METHODS

Interferon-gamma was measured as messenger RNA in liver-derived mononuclear leukocytes and as protein in liver-derived Natural Killer cells after a single injection of Augmenter of Liver Regeneration protein.

RESULTS

The data obtained demonstrate that: i) in intact rats, Augmenter of Liver Regeneration protein administration induces a reduction of Interferon-gamma in the liver-resident Natural Killer cells and ii) the administration of Interferon-gamma in 70% hepatectomized rats is followed by a significant reduction both of the mitochondrial transcription factor A expression and of liver regeneration.

CONCLUSIONS

These data demonstrate the pivotal role of Augmenter of Liver Regeneration as Growth Factor and as immunoregulator by controlling, through Interferon-gamma levels, the mitochondrial transcription factor A expression and the lytic activity of liver-resident Natural Killer cells.

From yeast to man--from mitochondria to liver regeneration: a new essential gene family

The purpose of this review is to bring to the attention of the reader the latest developments in research on an important new emerging gene family. The respective genes are found in eukaryotes from yeast to man and even on the genome of some doubled-stranded DNA viruses. They have essential functions in the biogenesis of mitochondria, the cell division cycle and, in higher eukaryotes, in the development of organs like liver and testis. The most important medical implication is their probable role in liver regeneration that will, therefore, be addressed in detail. Aspects of molecular biology, medical implications and problems of developmental biology reflect the complexity of the functions of these proteins and the subjects of the respective research. This is just the beginning of an interdisciplinary effort directed towards the elucidation of the precise function of these essential factors inside the eukaryotic cell. In the general part of this review, we will concentrate on the history of the discovery of these genes and on a summary of their characteristic features. In the more specialized section, the specific role as augmenter of liver regeneration will be addressed in detail.

Highly divergent amino termini of the homologous human ALR and yeast scERV1 gene products define species specific differences in cellular localization

The yeast scERV1 gene product is involved in the biogenesis of mitochondria and is indispensable for viability and regulation of the cell cycle. Recently the general importance of this gene for the eukaryotic cell was shown by the identification of a structural and functional human homologue. The homologous mammalian ALR (Augmenter of Liver Regeneration) genes from man, mouse and rat are involved in the phenomenon of liver regeneration. A low expression rate of the genes is found in all investigated cells and mammalian tissues but it is specifically induced after damage of liver organs and is especially high during spermatogenesis. The alignment of the different proteins identifies a highly conserved carboxy terminus with more than 40% identical amino acids between yeast and mammals. The conserved carboxy terminus is functionally interchangeable between distantly related species like yeast and man. In contrast, the amino terminal parts of the proteins display a high degree of variability and significant differences even among closely related species. This finding leads to the problem whether the amino termini have comparable or divergent functions in different species. In this study we demonstrate by heterologous complementation experiments in yeast that the complete human ALR protein with its own amino terminus is not able to substitute for the yeast scERV1 protein. Fusion proteins of Alrp and scErv1p with the green fluorescence protein were created to investigate the respective subcellular localizations of these homologous proteins in yeast and human cells. In yeast cells human Alrp accumulates in the cytoplasm in contrast to yeast scErv1p that is preferentially associated with yeast mitochondria. Comparable studies with human cells clearly show that the homologous human Alrp is located in the cytosol of these cells. Fractionation experiments and antibody tests with yeast and human mitochondria and cellular extracts verify these findings.

The in vivo effect of hepatotrophic factors augmenter of liver regeneration, hepatocyte growth factor, and insulin-like growth factor-II on liver natural killer cell functions

Fine balanced sequential changes of the levels of circulating hepatotrophic factors are essential for normal liver regeneration. Our recent studies have indicated that liver-resident natural killer (NK) cells are important regulators of liver regeneration and have raised the possibility that hepatotrophic factors might mediate their activities through NK cells. In the present study, we assessed the effects of in vivo administration of three hepatotrophic factors (augmenter of liver regeneration [ALR], insulin-like growth factor-II [IGF-II], and hepatocyte growth factor [HGF]) on NK cells in normal rats. Each of the three, given over a 1-day period in doses known to produce hepatotrophic activity, induced inhibition of NK cell cytotoxic activities in the population of mononuclear leukocytes (MNL) in the liver, but not in MNL from the spleen or peripheral blood. In contrast to these results obtained by the whole animal treatment, the three molecules had no effect on NK cell functions when added to cultures of MNL from the livers, spleens, or blood of untreated rats. These data support and extend our previously advanced hypothesis that ALR and other hepatotrophic factors play an important role in liver regeneration by regional regulation of NK cells through some as-yet-unknown intermediary mechanism.

The in vivo effect of hepatotrophic factors augmenter of liver regeneration, hepatocyte growth factor, and insulin-like growth factor-II on liver natural killer cell functions

Fine balanced sequential changes of the levels of circulating hepatotrophic factors are essential for normal liver regeneration. Our recent studies have indicated that liver-resident natural killer (NK) cells are important regulators of liver regeneration and have raised the possibility that hepatotrophic factors might mediate their activities through NK cells. In the present study, we assessed the effects of in vivo administration of three hepatotrophic factors (augmenter of liver regeneration [ALR], insulin-like growth factor-II [IGF-II], and hepatocyte growth factor [HGF]) on NK cells in normal rats. Each of the three, given over a 1-day period in doses known to produce hepatotrophic activity, induced inhibition of NK cell cytotoxic activities in the population of mononuclear leukocytes (MNL) in the liver, but not in MNL from the spleen or peripheral blood. In contrast to these results obtained by the whole animal treatment, the three molecules had no effect on NK cell functions when added to cultures of MNL from the livers, spleens, or blood of untreated rats. These data support and extend our previously advanced hypothesis that ALR and other hepatotrophic factors play an important role in liver regeneration by regional regulation of NK cells through some as-yet-unknown intermediary mechanism.

Proliferative activity of gastric epithelium in progressive stages of Helicobacter pylori infection

Helicobacter pylori (HP) infection is the main etiopathogenetic agent responsible for inflammatory and ulcerative changes in gastroduodenal mucosa and the basis for both intestinal and diffuse types of gastric carcinoma. In this latter case, intestinal metaplasia is the intermediary between gastritis and cancer. In this study we describe the proliferative activity of gastric epithelium in the progressive stages of HP infection. The expression of proliferating cell nuclear antigen (PCNA), which has proven to be a reliable method for this evaluation, was used as a marker. The study was performed on endoscopic biopsies of the gastric antrum of 40 patients, who were divided into five groups, eight in each group: normal histology and endoscopy, HP-; histological HP+ gastritis with normal endoscopy; histological HP+ gastritis with endoscopic evidence of chronic erosions; complete and incomplete intestinal metaplasia in a HP+ stomach. PCNA was detected by immunohistochemistry and expressed as labeling index, ie, percentage of positive nuclei either in the whole or upper third of foveolae. Our data show a progressive increase of epithelial proliferation in the successive stages of HP infection ranging from gastritis alone to the development of incomplete intestinal metaplasia, a well-known precancerous condition. The proliferative pattern tended to expand towards the upper foveolar third, which in normal conditions does not represent a site of epithelial renewal. These alterations may be related to the development of neoplastic transformations of gastric epithelium. It is well known that genetic mutations are facilitated in proliferating cells. Therefore, our results indicate that the high epithelial turnover, expressed by PCNA LI, may be an indicator of increased risk of neoplastic changes in long-standing untreated HP+ chronic gastritis.

Modulation of rat hepatocyte proliferation by bile salts: in vitro and in vivo studies

In this study, the stimulatory effect of bile salts (BS) was evaluated both in vitro, using hepatocyte primary cultures, and in vivo, in normal and 40% partially hepatectomized rats previously fed on BS-enriched diets for 4 weeks. In vitro results show that conjugated cholate (CA) and chenodeoxycholate (CDCA) augmented proliferative activity in rat hepatocytes cultured in absence of mitogens, whereas conjugated deoxycholate (DCA), and ursodeoxycholate (UDCA) did not have any significant effect. None of these BSs increased significantly the replicative response induced by submaximal concentrations of epidermal growth factor (EGF). In vivo, at the end of dietary treatment all animals fed on CA or DCA but not those fed on either CDCA, or UDCA, or tauroursodeoxycholate (TUDCA) developed cholestatic hepatitis and a burst of damage-induced hepatocyte proliferation. After 40% partial hepatectomy (PH), CA- and DCA-treated groups underwent a deterioration of cholestatic hepatitis. On the other hand, in CDCA-, and UDCA-, and TUDCA-treated groups liver histology, serum glutamic pyruvic transaminase (SGPT) and cholestasis indices did not change significantly compared with controls. As far as the proliferative activity, a significant increase was observed not only in CA and DCA but also in UDCA- and TUDCA-fed groups compared with controls, whereas a slight decrease was observed in CDCA-treated animals. In conclusion, our data indicate that conjugated BSs had only a modest stimulatory effect on hepatocyte proliferation in vitro. However, in vivo, in PH rats, UDCA or TUDCA treatment determined a further increase of hepatocellular proliferation not attributable to hepatotoxic effects. Our result suggest that modifications of bile acid pool could modulate hepatocellular proliferation.

Changes of liver-resident NK cells during liver regeneration in rats

To determine the role of NK cells in regulation of tissue growth, the phenotype and function of liver-resident NK cells were studied after 70% partial hepatectomy in rats. The process of liver regeneration was generally completed by day 14. In contrast, the number of liver-resident NK cells (NKR-P1bright) was restored as early as day 3 after partial hepatectomy. However, spontaneous functions of liver-resident NK cells, including killing of YAC-1 and P815 targets, Ab-dependent cellular cytotoxicity, and redirected killing via NKR-P1, were continuously suppressed throughout the entire period of liver regeneration (from 3 h to 14 days). Augmentation of NK cytotoxicity against P815 targets and induction of NK cell adherence to plastic following 24 h of IL-2 stimulation showed a similar pattern of suppression. However, IL-2-induced augmentation of YAC-1 killing, proliferation and generation of adherent NK cells, and LAK activity in 5- to 7-day cultures were found to be suppressed only during the first 24 h and increased between days 2 and 7 after hepatectomy. Sorted NK cells (> or = NKR-P1bright) from liver-resident mononuclear leukocytes 24 h after partial hepatectomy showed the same pattern of suppression as unsorted mononuclear leukocytes. In contrast to liver-resident NK cells, no significant changes were detected in peripheral blood or spleen NK cells of rats following partial hepatectomy. Of particular interest, in normal liver, hepatocytes were resistant to NK lysis, while resident NK cells were cytotoxic for various NK-sensitive targets. In contrast, during the early period of liver regeneration, when hepatocytes were sensitive to lysis by liver-resident NK cells of normal rats, NK cells obtained from regenerating liver tissues were unable to mediate cytotoxicity. At the final phase of liver regeneration (days 7-14 after hepatectomy), both resistance of hepatocytes to killing by NK cells and cytotoxicity of liver-resident lymphocytes against hepatocytes from regenerating liver were simultaneously restored. In vivo depletion of NK cells by injection of rats with anti-NKR-P1 mAb resulted in a significant augmentation of liver regeneration subsequent to partial hepatectomy. Our data suggest that liver-resident NK cells may be involved in regulation of the extent of liver regeneration.

Changes of liver-resident NK cells during liver regeneration in rats

To determine the role of NK cells in regulation of tissue growth, the phenotype and function of liver-resident NK cells were studied after 70% partial hepatectomy in rats. The process of liver regeneration was generally completed by day 14. In contrast, the number of liver-resident NK cells (NKR-P1bright) was restored as early as day 3 after partial hepatectomy. However, spontaneous functions of liver-resident NK cells, including killing of YAC-1 and P815 targets, Ab-dependent cellular cytotoxicity, and redirected killing via NKR-P1, were continuously suppressed throughout the entire period of liver regeneration (from 3 h to 14 days). Augmentation of NK cytotoxicity against P815 targets and induction of NK cell adherence to plastic following 24 h of IL-2 stimulation showed a similar pattern of suppression. However, IL-2-induced augmentation of YAC-1 killing, proliferation and generation of adherent NK cells, and LAK activity in 5- to 7-day cultures were found to be suppressed only during the first 24 h and increased between days 2 and 7 after hepatectomy. Sorted NK cells (&gt; or = NKR-P1bright) from liver-resident mononuclear leukocytes 24 h after partial hepatectomy showed the same pattern of suppression as unsorted mononuclear leukocytes. In contrast to liver-resident NK cells, no significant changes were detected in peripheral blood or spleen NK cells of rats following partial hepatectomy. Of particular interest, in normal liver, hepatocytes were resistant to NK lysis, while resident NK cells were cytotoxic for various NK-sensitive targets. In contrast, during the early period of liver regeneration, when hepatocytes were sensitive to lysis by liver-resident NK cells of normal rats, NK cells obtained from regenerating liver tissues were unable to mediate cytotoxicity. At the final phase of liver regeneration (days 7-14 after hepatectomy), both resistance of hepatocytes to killing by NK cells and cytotoxicity of liver-resident lymphocytes against hepatocytes from regenerating liver were simultaneously restored. In vivo depletion of NK cells by injection of rats with anti-NKR-P1 mAb resulted in a significant augmentation of liver regeneration subsequent to partial hepatectomy. Our data suggest that liver-resident NK cells may be involved in regulation of the extent of liver regeneration.

Does tauroursodeoxycholic acid (TUDCA) treatment increase hepatocyte proliferation in patients with chronic liver disease?

Despite numerous studies on the effects of bile salts therapy in chronic liver disease, there are no reports on the influence such therapy has on hepatocyte proliferation. The aim of this preliminary study was to evaluate the effect of TUDCA on hepatocyte proliferation in 5 patients with HCV-correlated chronic liver disease. All patients were treated with TUDCA (10-13 mg/day) for three months and the determination of PCNA (Proliferating Cell Nuclear Antigen) expression was used to assess the proliferative activity of hepatocytes at the beginning and at the end of treatment. TUDCA reduced both ALT and Knodell's score in the 5 patients in whom a significant increase of PCNA-LI (p < 0.05) was observed after treatment. TUDCA administration seems to stimulate hepatocyte proliferation in man.

Cell proliferation and oncogene expression after bile duct ligation in the rat: evidence of a specific growth effect on bile duct cells

The proliferative response of the rat liver was measured after temporary or permanent total biliary obstruction (BDO) and in different regions after selective ligation of the lobar ducts draining the right 60% of the hepatic mass. The results were compared with those after 70% partial hepatectomy (PH). Cell proliferation was assessed globally by measuring DNA synthesis and stratified to the separate cell populations with cytostaining techniques that allowed distinction of hepatocytes, duct cells, and nonparenchymal cells (NPCs). In selected experimental groups, gene expression was determined of transforming growth factor-beta 1 (TGF beta-1), prothrombin, c-erb-B2, transforming growth factor alpha (TGF alpha), human Cyclophilin (CyP), and 28S ribosomal RNA. The stimulation of a proliferative response to total BDO required obstruction for longer than 24 hours, but after this deligation did not switch off regeneration. In the first week after permanent BDO, there was progressive infiltration of NPCs, fibrous linkage of some portal areas, and a crescendo of DNA synthesis that was obvious at 24 hours, maximal at 48 hours, and back nearly to baseline at 6 days. At the 2-day mark, the bile duct cells had a 17-fold increase in proliferation, accompanied by a threefold to fourfold increase in hepatocyte renewal. Little or no increase in expression of TGF alpha or the hepatocyte-specific prothrombin gene was detectable in the first 48 hours, whereas levels of the oncogene c-erb-B2 that is associated with cholangiocarcinoma were expressed from 48 to 96 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatocyte proliferation and gene expression induced by triiodothyronine in vivo and in vitro

Subcutaneous injections of hormone triiodothyronine in rats resulted in peak blood levels at 24 hr with return to baseline by 96 hr. The injections stimulated a liver regeneration response that resembled in timing and in magnitude of DNA synthesis (peak, 24 hr) that induced by 40% hepatic resection. The principal proliferation was of hepatocytes. Although there were some temporal differences from the gene expression of transforming growth factor-alpha, transforming growth factor-beta, and c-Ha-ras that are known to follow partial hepatectomy, the overall profile of these changes was similar to those after partial resection. The effect was liver specific and could be reproduced three times with no diminution in response in the same animal with injections at 10-day intervals. No response was detected in kidney or intestine. This effect in intact animals contrasted with the minimal ability of triiodothyronine to stimulate hepatocytes in culture. However, when the culture medium was enriched with epidermal growth factor, there was a dose-related response to triiodothyronine. The totality of these experiments provides a preliminary basis for the creation with pharmacological techniques of an in vivo hyperplastic hepatic condition permissive of transfection of new genes, as an alternative to partial hepatectomy. Although triiodothyronine was the test agent used, other hepatic growth factors singly or in combination could be candidates for this purpose.

Cloning and sequence analysis of the rat augmenter of liver regeneration (ALR) gene: expression of biologically active recombinant ALR and demonstration of tissue distribution

A full-length cDNA clone encoding a purified augmenter of liver regeneration (ALR) factor prepared from the cytosol of weanling rat livers was isolated. The 1.2-kb cDNA included a 299-bp 5' untranslated region, a 375-bp coding region, and a 550-bp 3' untranslated region. It encoded a protein consisting of 125 amino acids. The molecular weight of ALR calculated from the cDNA was 15,081, which is consistent with the size estimated by SDS/PAGE under reducing conditions. The molecular weight of the purified native ALR estimated by SDS/PAGE under nonreducing conditions was approximately 30,000; thus ALR apparently has a homodimeric structure. The recombinant ALR produced by expression of the cDNA in COS cells was tested in vivo in the canine Eck fistula model and found to have potency equivalent to the purified native ALR. The 125-aa sequence deduced from the rat ALR cDNA shows 50% homology to the amino acid sequence of the gene for oxidative phosphorylation and vegetative growth in the yeast Saccharomyces cerevisiae.

Estrogens, androgens, and EGF receptor expression in gastric carcinoma induced by N-methyl-N'-nitro-N-nitrosoguanidine

Complex and conflicting relationships between epidermal growth factor (EGF), estrogens (E), androgens (A), and related receptors (EGF-R, E-R, A-R) have been reported in different biological situations associated with cell proliferation. There is also evidence that EGF and sex hormone receptors may be involved in normal and neoplastic growth of the gastrointestinal mucosa. In this study, we investigated the behavior of EGF receptors and sex hormone and related receptors, during N-methyl-N'-nitro-N-nitrosoguanidine (NG)-induced gastric carcinogenesis in Sprague-Dawley male rats. Four groups of 15 rats each (10 NG-treated and five controls) were sacrificed after 1, 20, 30, and 40 weeks of treatment. Gastric tissue from each rat was processed for receptor status (number and affinity) and proliferative activity. A significant and progressive decrease of A-R and EGF-R was observed starting from the 20th week, while no change of E-R occurred throughout the experiment. Cell proliferation in the gastric mucosa of NG-treated rats increased after 30 weeks of treatment. These data indicate that NG treatment is able to modify the receptor status of gastric mucosa in rats.

Small-for-size liver transplanted into larger recipient: a model of hepatic regeneration

Orthotopic liver transplantation was performed in 60 recipient rats weighing 200 to 250 gm. Sixty rats of the same strain were used as liver donors, 30 weighing 100 to 140 gm (small for size) and the other 30 weighing 200 to 250 gm (same size). After 1, 2, 3, 4, 7 and 14 days (n = 5 each) DNA synthesis, nuclear thymidine labeling and mitoses were increased in both the small-for-size and same-size groups, but significantly more in the former. These changes were maximal after 48 to 72 hr, similar to but later than the well-known regeneration response after partial hepatectomy, which peaks at 24 hr in rats. Indirect indexes of regeneration of the transplanted livers also were measured: plasma or serum ornithine decarboxylase; insulin and glucagon serum levels; estradiol and testosterone serum levels (and their nuclear and cytosolic receptors); and transforming growth factor-beta, c-Ha-ras and c-jun mRNA expressions. With the small-for-size transplantation, these followed the same delayed pattern as the direct regeneration parameters. The small livers gradually increased in size over the course of 1 to 2 wk and achieved a volume equal to that of the liver originally present in the recipient. In contrast, no significant liver weight gain occurred in the transplanted livers from same-size donors despite the evidence of regeneration by direct indexes, but not by most of the surrogate parameters, including ornithine decarboxylase.

Interphasic nucleolar organizer regions expression and cell kinetics evaluation during gastric carcinogenesis induced by nitrosoguanidine in the rat

An increased number of interphasic nucleolar organizer regions containing ribosomal cistrons associated with argyrophilic proteins (AgNORs) has been described in human malignant tumor cells. In this study variations in AgNOR numbers have been compared with changes of cell kinetics, evaluated by the mitotic count (MC) and bromodeoxyuridine labeling index (BrdU LI), during gastric carcinogenesis induced with N-methyl-N'-nitro-N-nitrosoguanidine (NG) in rats. Significant differences (2 P < 0.005) in AgNOR mean numbers, evaluated in the antral isthmic cells, in MC mean values and BrdU LI, evaluated in the whole antral cellular population, were found when comparing areas of acute gastritis, atrophy and hyperplasia in NG-treated rats with the normal mucosa in controls. No differences were observed in MC and BrdU LI between normal antrum and carcinoma cells which showed an AgNORs mean number lower than in the isthmic cells of controls (2 P < 0.005). Moreover, significant correlations were found comparing changes in AgNOR numbers with MC (r = 0.89, P < 0.001) and BrdU LI (r = 0.66, P < 0.001) in different lesions. These data show that evaluation of AgNOR numbers does not allow the identification of malignant cells in NG-induced gastric carcinoma. However AgNOR quantification seems to be a reliable index of cell kinetics and related well with the cellular dividing fraction.

Relationship between plasma and hepatic cytosolic levels of ornithine decarboxylase (ODC) and thymidine kinase (TK) in 70% hepatectomized rats

Ornithine decarboxylase (ODC) and thymidine kinase (TK) are enzymes important for DNA synthesis, a process that is critical for cell renewal and regeneration. As such, they already have been used as surrogate markers of regeneration in tissue. In the present study, the activity of these two enzymes in plasma of rats and regenerating hepatic tissue following a 70% hepatectomy were determined. The results demonstrate that the changes in these enzyme activities in plasma reflect the changes obtained in the liver tissue. Thus, blood levels of ODC and TK can be used as a less invasive and nondestructive means of monitoring the regenerative response of the liver and possibly other tissues.

Hormonal and enzymatic parameters of hepatic regeneration in patients undergoing major liver resections

Thirteen patients who underwent 40% to 80% removal of their livers had blood samples drawn initially and daily on postoperative days 1 to 7. The enzyme marker of heightened polyamine metabolism, ornithine decarboxylase, and the indicator of DNA synthesis, thymidine kinase, were measured. In addition, the hormones (insulin, glucagon, estradiol and androgen), which in animals are known to reflect and possibly modulate regeneration, were measured. Changes in all these indices followed the same pattern as in rats, dogs and swine but at a slower rate. Ornithine decarboxylase and estradiol increased within 24 hr, but thymidine kinase and insulin rises did not become statistically significant until 3 to 5 days. Using these plasma or serum indices as surrogate measures of biochemical events in the liver itself, regeneration reached a maximum after 4 or 5 days. By computed tomography scan analysis, restoration of hepatic cell mass was not complete until 3 wk.

Effect of ranitidine on acetaminophen-induced hepatotoxicity in dogs

The effect of ranitidine administration upon the hepatotoxic effect produced by a multidose acetaminophen administration regimen was examined. Seventy-two dogs received three subcutaneous injections of acetaminophen (750, 200, 200 mg/kg body wt) in DMSO (600 mg/ml) at time zero, 9 hr later, and 24 hr after the first dose. Ten control animals (group I) were not given ranitidine, the remaining 62 dogs received an intramuscular injection of ranitidine 30 min before each acetaminophen dose. Three different doses of ranitidine were used (mg/kg body wt): 50 mg, group II (33 dogs); 75 mg, group III (14 dogs); 120 mg, group IV (15 dogs). Ranitidine reduced the expected acetaminophen-induced hepatoxicity in a dose-response manner. Moreover, a significant correlation was found between the ranitidine dose and the survival rate, as evidenced by transaminase levels in the serum and histology of the liver. This model of fulminant hepatic failure induced by acetaminophen and its modulation with ranitidine provides clinical investigators with a research tool that will be useful in the future investigation of putative medical and surgical therapies being investigated for use in the clinical management of fulminant hepatic failure. Because of the size of the animal used in this model, frequent and serial analyses of blood and liver were available for study to determine the effect of therapy within a given animal as opposed to within groups of animals.

The effect of estrogen and tamoxifen on hepatocyte proliferation in vivo and in vitro

We have previously shown that changes in estrogen-hepatocyte interaction occur during liver regeneration. Following 70% hepatectomy, estrogen levels in the blood were elevated, the number of estrogen receptors in the liver was increased and there was an active translocation of estrogen receptors from the cytosol to the nucleus. The injection of tamoxifen, an estrogen antagonist, inhibits hepatocyte proliferation following partial hepatectomy. The administration of 1 microgram tamoxifen per gm body weight at zero time or 6 hr after the operation resulted in a significant inhibition both of DNA synthesis and of the number of cells in mitosis. Injections of tamoxifen 12 hr or later after the operation had no effect. Concomitant injections of equimolar amounts of estrogen abolished the inhibition by tamoxifen. The effects of estrogen and tamoxifen were also tested on hepatocytes in primary culture. Estrogens in the presence of 5% normal rat serum stimulated hepatocyte DNA synthesis as determined by [3H]thymidine incorporation and the labeling index, whereas epidermal growth factor-induced DNA synthesis in the absence of normal rat serum was strongly inhibited. Tamoxifen, in contrast, inhibited DNA synthesis of hepatocytes in the presence of 5% normal rat serum and reversed the stimulatory effect of estrogen in the same system. Attempts to elucidate the mechanism of tamoxifen inhibition in vitro indicated that one effect of tamoxifen is to prevent the amiloride-sensitive Na+ influx necessary to initiate hepatocyte proliferation.

A dog model for acetaminophen-induced fulminant hepatic failure

The development of a large animal model of fulminant hepatic failure produced with acetaminophen that should be useful in the development and evaluation of potential medical therapies for the important clinical problem of fulminant hepatic failure is described. Acetaminophen in dimethyl sulfoxide (600 mg/ml) given as three subcutaneous injections, with the first dose (750 mg/kg body wt) being given at noon, the second dose (200 mg/kg body wt) being given 9 h later, and the third dose (200 mg/kg body wt) being given 24 h after the initial dose consistently produces fulminant hepatic failure in dogs. The dimethyl sulfoxide vehicle, injected intramuscularly, does not influence either animal survival or hepatic function in control-treated dogs. No deaths occur within the first 36 h. By 72 h after initial drug administration, the mortality is 90%. Histopathological and biochemical investigations demonstrate a high degree of hepatocellular necrosis in nonsurviving animals without appreciable damage to the kidneys, lungs, or heart. The drug schedule and preparation outlined avoids the administration of large volumes of vehicle and results in prolonged high levels of acetaminophen in the blood sufficient to induce severe hepatic injury. Ranitidine (120 mg/kg body wt i.m.) given 30 min before each acetaminophen dose significantly reduces the mortality and hepatic necrosis produced using this model. This model satisfies all criteria established by Miller et al. for the production of a suitable large animal model of fulminant acute hepatic failure.

Effect of cimetidine, ranitidine, famotidine and omeprazole on hepatocyte proliferation in vitro

Recently reports have indicated that both cimetidine and ranitidine delay cell proliferation in rats following 70% partial hepatectomy and result in an increased mortality following this procedure. The present study was designed to determine whether three H2 blocking agents (cimetidine, ranitidine, famotidine) and a new, powerful antisecretory drug (omeprazole) specifically influence hepatocyte proliferation in primary culture. Hepatocytes were isolated from livers of normal male rats by the standard collagenase perfusion technique. Hepatic DNA synthesis and percent of labelled nuclei were determined after 48 h incubation. Hepatocytes in culture were incubated with the H2 blocking agents and omeprazole or with different concentrations of serum obtained from sham-operated or 70% hepatectomized rats treated or not with the same agents. Rats were injected intraperitoneally at 8:00 a.m. on two consecutive days. In hepatectomized rats, the first dose was injected at 8:00 a.m. immediately after surgery, the second, 24 h later. The serum of sham-operated or 70% hepatectomized rats that did not receive drugs served as control. No changes in DNA synthesis, percentage of labelled nuclei and transaminase were detected when the agents were added to the hepatocytes in culture at concentrations within the effective pharmacological dosage and 30 times higher. Similarly, no changes in these parameters were obtained when different concentrations of serum obtained from sham-operated rats treated with H2 blocking agents or omeprazole were added to the basal culture medium. However, a significant inhibition of DNA synthesis and of percentage of labelled nuclei was observed when hepatocytes were incubated in the presence of serum from 70% hepatectomized rats that had been treated with cimetidine or with ranitidine. The serum of 70% hepatectomized rats treated with famotidine and omeprazole had no effect on hepatocyte proliferation in vitro. No effect on transaminase was found in these conditions.

Nuclear and cytosolic estrogen receptors in human colon carcinoma and in surrounding noncancerous colonic tissue

The measurement of estrogen as well as progesterone receptors has been applied clinically to predict the effectiveness of endocrine therapy in patients with breast or endometrial carcinoma. The presence of cytosolic estrogen receptors in human colorectal carcinomas has been reported by several different groups during the past 10 yr. The aim of our current study was to evaluate the estrogen binding activity in the nuclear and cytosolic fractions of these carcinomas, as well as in surrounding noncancerous colonic tissue. Twenty-six patients, operated on for colorectal carcinoma, were studied: 16 were men and 10 were postmenopausal women, mean age 61 yr (range 43-78 yr). In neoplastic tissue, cytosolic estradiol receptors were detected in 42.3% of the patients (women 40%, men 43.7%). The values for cytosolic estrogen receptor ranged from 118 to 1214 fmol/g wet colon. Nuclear estrogen receptors were detectable in 46.1% of the patients (women 40%, men 50%) and their values displayed a range from 3.4 to 2554 fmol/g wet colon. In 30.7% of the patients, both nuclear and cytosolic receptors were demonstrated. In 38.4% of the patients, receptors were found in neither cytosol nor nuclei. Receptor positivity in men was most frequently associated with tumors removed from the rectum, and those with Dukes' classification of C1. In the surrounding noncancerous tissue cytosolic estrogen receptors were also detected (range 133-1105 fmol/g wet colon) and were present in 34.6% of the patients (women 30%, men 37.5%). Nuclear estrogen receptors (range 225-1105 fmol/g wet colon) were detected in 57.6% of the patients (women 40%, men 68.7%). In 23% of the patients, both nuclear and cytosolic receptors were demonstrated. In 30.7% of the patients, no receptors were found in either cytosol or nucleus. Therefore, the presence of cytosolic or nuclear estrogen receptors, or both, in 61.6% of human colorectal cancer specimens emphasizes the need to evaluate both forms of these receptors for studies of potential hormone dependence in these tumors.

Rapid growth of an intact human liver transplanted into a recipient larger than the donor

Two individuals undergoing orthotopic hepatic transplantation received livers from donors who were on average 10 kg smaller than themselves based on recipient ideal body weight. As a result, the donor livers in these 2 cases were 29%-59% smaller than would be expected had the donor liver and recipient been matched ideally. The liver grafts in the recipients steadily increased in size, as determined by serial computed tomography scanning, to achieve new volumes consistent with those that would have been expected in a normal individual of the recipient's size, sex, and age. Fasting plasma levels of amino acids, glucagon, insulin, and standard liver injury tests were monitored to determine which measure best reflected the changes observed in the size of the grafts over time. No relationship between the changes observed in any of these parameters and hepatic growth was apparent. In both cases, the liver increased in volume at a rate of approximately 70 ml/day. These data demonstrate that a small-for-size liver transplanted into a larger recipient increases in size at a rate of approximately 70 ml/day until it achieves a liver volume consistent with that expected given the recipient's size, age, and sex.

Extraction and partial purification of a hepatic stimulatory substance in rats, mice, and dogs

A factor has been isolated from weanling rat liver which stimulates in vivo hepatic DNA synthesis in a dose dependent manner when injected into 40% hepatectomized rats. The factor has been partially purified by successive steps, involving ethanol precipitation, ultrafiltration through an Amicon PM 30 membrane, and finally fast protein liquid chromatography, resulting in a 38,000-fold increase in specific activity over that in the original cytosol. The factor contains a few bands in the molecular weight range of 14,000-50,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Active fractions from fast protein liquid chromatography (F150), when injected into 40% hepatectomized rats, increased hepatic DNA synthesis 3-fold over the background stimulation due to the hepatectomy. The response was dose dependent over a range from 1.76 micrograms to 6.8 micrograms per 200-g (body weight) rat. Mitotic and labeling indexes confirmed that F150 stimulates both replicative DNA synthesis and cell proliferation. The factor is heat and neuraminidase resistant, trypsin sensitive, organ specific, but not species specific.

Effect of spironolactone and potassium canrenoate on cytosolic and nuclear androgen and estrogen receptors of rat liver

Spironolactone and potassium canrenoate are diuretics that are used widely for management of cirrhotic ascites. The administration of spironolactone frequently leads to feminization, which has been noted less frequently with the use of potassium canrenoate, a salt of the active metabolite of spironolactone. The use of these two drugs has been associated with decreases in serum testosterone levels and spironolactone with a reduction in androgen receptor (AR) activity. This decrease in AR has been cited as the cause of the antiandrogen effect of these drugs. We therefore assessed the effect of both drugs on levels of androgen and estrogen receptors (ER) in the liver, a tissue that is responsive to sex steroids. Three groups of male rats (n = 12 rats each) were studied. Group 1 (control) received vehicle only; group 2 received spironolactone (5 mg/day); group 3 received potassium canrenoate (5 mg/day). After 21 days of treatment, the animals of all groups were killed and liver tissue was assayed for nuclear and cytosolic AR and ER, and for male specific estrogen binder (MEB), an androgen-responsive protein. Both drugs drastically decreased the nuclear AR content, as compared with the control group, but only spironolactone decreased cytosolic AR. When the total hepatic content of AR is considered, a highly significant decrease is observed only in rats treated with spironolactone. This reduction in hepatic AR content suggested loss of androgen responsiveness of liver. We confirmed this by assessing levels of MEB, and found that livers from group 2 animals had no detectable MEB activity, whereas livers from both group 1 and 3 had normal MEB activity. No changes were observed in nuclear ER and cytosolic ER of group 3 as compared with group 1. Nuclear estrogen receptor decreased and cytosolic ER increased in group 2, but with no change in total ER content. These results indicate that (a) only spironolactone appears to act as an antiandrogen in liver, resulting in a decrease in both AR and male specific estrogen binder content, and (b) neither drug results in elevated hepatic ER content, although spironolactone-treated animals show an altered subcellular localization.

Different response to epidermal growth factor of hepatocytes in cultures isolated from male or female rat liver. Inhibitor effect of estrogen on binding and mitogenic effect of epidermal growth factor

Deoxyribonucleic acid (DNA) synthesis in hepatocytes isolated from the livers of male and female rats has been compared in monolayer culture. Plating efficiency, DNA and protein content, viability, and morphologic appearance were the same in cultures prepared with hepatocytes isolated from male or female rats. Epidermal growth factor (EGF)-induced DNA synthesis was significantly higher in hepatocytes from male rats than in hepatocytes from female rats. This was the case whether hepatocytes were isolated from normal or partially hepatectomized male or female rats. Hepatocytes isolated from regenerating liver synthesize more DNA than those isolated from normal liver in response to EGF. This increased response to EGF in hepatocytes derived from regenerating liver was relatively the same for male- and female-derived hepatocytes, but the magnitude of the response was considerably higher in male-derived hepatocytes. In contrast, in vivo DNA synthesis in the liver remnant after partial hepatectomy was similar in male and female rats if measured 24 h after the operation. A comparison of EGF binding to male- and female-derived hepatocytes maintained in primary culture indicated a lower number of high-affinity receptors for EGF in the female hepatocytes. The addition of estrogen to primary cultures of hepatocytes isolated from male rats inhibited EGF binding as well as EGF-induced DNA synthesis. Our studies show significant differences in DNA synthesis in response to EGF when male and female hepatocytes are compared in primary culture. The regenerative response after partial hepatectomy, on the other hand, was the same in male and female rats. Thus, our studies indicate that the sex of the donor, rat is important when hepatocytes in culture are used for a variety of studies, such as hepatocyte metabolism, induction and control of DNA synthesis, and hepatocarcinogenesis. In addition, our results indicate that caution is advised when inferences are made from in vitro findings for in vivo conditions.

Pancreatic hormones and amino acid levels following liver transplantation

Glucose intolerance, hyperinsulinemia, peripheral insulin resistance and hyperglucagonemia are common in patients with advanced liver disease. These abnormalities in the plasma levels of the pancreatic hormones, insulin and glucagon have been thought to be responsible, at least in part, for the abnormal plasma ratio of branched-chain amino acids to aromatic amino acids. To evaluate this issue, plasma levels of glucose, insulin, glucagon, C-peptide and the branched-chain and aromatic amino acids were measured before and serially after orthotopic liver transplantation in 9 humans and 5 dogs. The abnormal plasma amino acid levels rapidly improved and achieved normal levels following orthotopic liver transplantation. Insulin levels also became normal following orthotopic liver transplantation, despite enhanced insulin secretion documented by an even further increased level of C-peptide. In contrast, the baseline abnormal plasma glucagon levels which are commonly seen in cirrhotics became even more abnormal following orthotopic liver transplantation. Despite this progressive increase in the abnormally elevated plasma glucagon levels, plasma amino acid levels, both branched-chain and aromatic, became normal. These data demonstrate that before and after orthotopic liver transplantation, there is: (i) no relationship between the changes in the plasma levels of glucagon and changes observed in the plasma level of amino acids; and (ii) plasma insulin and amino acid levels change in the same direction. In addition, these changes in plasma insulin and amino acid levels following orthotopic liver transplantation occur despite enhanced secretion of insulin evidenced by the progressive increase in plasma levels of C-peptide.

Evidence that host size determines liver size: studies in dogs receiving orthotopic liver transplants

Orthotopic liver transplantation was performed in two groups of dogs; Group I animals consisted of large dogs that served as recipients of livers obtained from smaller dogs while Group II animals consisted of dogs that received liver from donor dogs of nearly the same size. The small-for-size livers transplanted into the Group I dogs rapidly increased in size over the course of 2 weeks until they achieved a size equal to that originally present in the larger recipient dogs. In contrast, the livers transplanted into dogs of the same size as the donors underwent some degree of atrophy. In both groups of animals, plasma levels of insulin and glucagon and hepatic (graft) activities of thymidine kinase and ornithine decarboxylase were followed serially. The only difference between the two groups of animals for these measures was that the ornithine decarboxylase activity rose to a greater degree in the liver that underwent graft enlargement. These data suggest that recipient size determines, at least in part, liver graft size once it is transplanted. These data also suggest that of the parameters followed, only ornithine decarboxylase activity parallels the finding of growth of the transplanted liver.

Glucose metabolism during liver transplantation in dogs

Arterial and hepatic venous blood levels of glucose were studied in 12 dogs during orthotopic liver transplantation performed under ketamine anesthesia without exogenous glucose administration. During the early part of surgery, arterial blood glucose levels were stable: 161 +/- 12 mg/dl (mean +/- SEM) after laparotomy and 183 +/- 16 mg/dl 5 min before the anhepatic stage. During the anhepatic stage, arterial blood glucose levels decreased progressively to 135 +/- 9 and 88 +/- 8 mg/dl, 5 min in the anhepatic stage and 5 min before reperfusion of the graft liver, respectively (P less than 0.05). Reperfusion of the graft liver resulted in an increase in arterial glucose levels to 206 +/- 17 and 240 +/- 24 mg/dl, 5 and 30 min after reperfusion, respectively (P less than 0.05). Hepatic venous blood glucose levels increased after reperfusion (405 +/- 37 and 346 +/- 41 mg/dl, 5 and 30 min after reperfusion, respectively) and were significantly higher than in arterial blood (P less than 0.05). Arterial plasma insulin, measured in five animals, did not change significantly during the procedure, whereas plasma glucagon levels, stable during the preanhepatic and anhepatic stages, increased steadily after reperfusion of the graft liver, from 66.1 +/- 14.2 to 108.4 +/- 38.1 pg/ml (P less than 0.05). This study shows that in dogs with ketamine anesthesia mild hypoglycemia occurs during the anhepatic stage of liver transplantation without exogenous glucose administration followed by hyperglycemia on reperfusion of the graft liver, possibly secondary to the release of glucose from the donor liver.

Sex hormone-related functions in regenerating male rat liver

Sex hormone receptors were quantitated in normal male rat liver and in regenerating liver at several different times after partial (70%) hepatectomy. Both estrogen and androgen receptor content were altered dramatically by partial hepatectomy. Total hepatic content and nuclear retention of estrogen receptors increased, with the zenith evident 2 days after partial hepatectomy, corresponding to the zenith of mitotic index. Serum estradiol increased after 1 day, and reached a maximum at 3 days after surgery. In contrast, total and nuclear androgen receptor content demonstrated a massive decline at 1, 2, and 3 days after resection. Serum testosterone displayed a parallel decline. In addition, hepatic content of two androgen-responsive proteins was reduced to 15% and 13% of normal values during this period. The activity of these various proteins during regeneration of male rat liver is comparable to that observed in the liver of normal female rats. Taken together, these results indicate that partial hepatectomy induces a feminization of certain sexually dimorphic aspects of liver function in male rats. Furthermore, these data provide evidence that estrogens, but not androgens, may have an important role in the process of liver regeneration.

Circadian rhythm of hepatic cytosolic and nuclear estrogen and androgen receptors

Mammalian liver is a sex steroid-responsive tissue. The effects of these hormones presumably are mediated by hepatic estrogen receptors (ER) and androgen receptors (AR). Serum levels of sex hormones display circadian rhythms. Further, estrogens and androgens are commonly administered; administration of these agents is associated frequently with liver disease. Therefore, we investigated whether the cytosolic and nuclear sex steroid receptors also display a similar circadian rhythm, and whether variations occurred in the distribution of receptors between cytosolic and nuclear compartments. Animals were killed every 4 h from midnight till the following midnight; cytosolic and nuclear levels of both ER and AR were measured. Cytosolic ER reached a maximum level at 4 AM, and a minimum at 8 PM and midnight of both days. Nuclear ER was highest at 8 AM and lowest at 4 PM and 8 PM, a pattern which parallels variations in serum estradiol levels. Cytosolic AR was highest at 8 PM and lowest at midnight and 4 AM. Nuclear AR was highest at 4 AM and lowest at 4 PM and 8 PM. The highest level of nuclear AR does not correspond to the maximum serum testosterone level, which occurred at 4 PM. The total hepatic content of both ER and AR was not constant over the 24-h period, but varied considerably with time of day. These studies suggest that both ER and AR show a distinct circadian rhythm in subcellular compartmentalization, and that total hepatic content of ER and AR varies significantly during a 24-h period.

Epidermal growth factor and proliferation in rat hepatocytes in primary culture isolated at different times after partial hepatectomy

Primary hepatocyte cultures have been prepared from normal adult rat liver and from rat liver at 4, 8, 12, 24, and 48 h following partial hepatectomy (removal of 70% of the liver). Cells were maintained in minimal essential medium alone or supplemented with hormones. Comparing DNA synthesis in normal adult rat hepatocytes with DNA synthesis in hepatocytes isolated from regenerating livers, we found with minimal essential medium alone little DNA synthesis in normal adult rat hepatocytes and in hepatocytes isolated 4, 8, or 12 h after 70% hepatectomy. In hepatocytes isolated 24 h after partial hepatectomy, however, the incorporation of [3H]thymidine was 3 times the rate of normal hepatocytes. The addition of insulin to minimal essential medium had minimal effect on DNA synthesis in all hepatocytes. Addition of epidermal growth factor alone or in combination with insulin resulted in a dramatic increase in DNA synthesis in hepatocytes from regenerating rat liver. Increased incorporation was detectable as early as 4 h after partial hepatectomy and reached a maximum at 24 h after the operation. Results obtained with [3H]thymidine incorporation were confirmed by autoradiography and by direct DNA determinations in hepatocyte cultures. Epidermal growth factor binding to the hepatocytes was determined and agreed with previously reported binding studies. Binding of epidermal growth factor in hepatocytes isolated at 4 h after partial hepatectomy was the same as in normal hepatocytes but was undetectable in hepatocytes isolated from rats at 12 and 24 h after partial hepatectomy.