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PubMedDate not supplied

[Metabolism of different histone fractions under induction of rat liver regeneration].

Histone metabolism in liver studied within 72-hour period of liver regeneration after partial hepatectomy in 24 hours after the injection of 14C-amino acids in rats. The increase in radioactivity of f2a, f3 and f2b histones and the simultaneous decrease in f1 histone radioactivity was observed in regenerating rat liver as compared with the level of radioactivity estimated for the respective histones in ectomized liver lobes. These changes, which are characteristic for regenerating liver, were not observed after the shame operation and they did not eliminate after the injection of respective unlabelled amino acid. Possible correlation between the increase in specific radioactivity of most nuclear histones under regeneration process and a migration of pre-synthesized labelled histone molecules into nucleus, and also a transformation into histones of other nuclear proteins is discussed.

Animals↗
PubMed1990

Liver regeneration: molecular mechanisms of growth control.

The molecular signals controlling liver regeneration are becoming rapidly defined. Control of growth in regenerating liver has advanced from elusive serum factors and nutrient effects to identification of entirely new growth factors with apparent liver specificity as well as establishment of meaningful gene expression patterns for growth factors already known. Based on studies with hepatocyte cultures and gene expression in regenerating liver, the substances EGF, TGF alpha, HBGF-1 (aFGF), and two new substances (HPTA/HGF and Hepatopoietin B) have been defined as complete mitogens for hepatocytes and implicated in control of liver growth. The amino acid sequence of HPTA/HGF recently became clear and revealed interesting structural homologies in a molecule that might become the largest known growth factor. The plasticity of growth responses seen in liver may be controlled by these factors as well as by comitogenic substances such as norepinephrine which, although nonmitogenic per se, can initiate growth in hepatocytes exposed to the above mitogenic growth factors or mitogenic inhibitors such as TGF beta. The role of the latter in cessation of DNA synthesis in liver regeneration will be discussed, presenting the positive and negative evidence that constitutes the TGF beta paradox of liver regeneration.

Amino Acid Sequence↗
PubMed2004

Liver regeneration using a hybrid artificial liver support system.

We have developed two types of hybrid artificial liver support system (HALSS) that use hepatocyte organoid culture: (1) a PUF-HALSS comprising an artificial liver module using polyurethane foam (PUF), in which hepatocytes form spheroids in its pores, and maintained liver-specific functions for at least ten days in vitro; (2) an LLS-HALSS that uses a liver lobule-like structure (LLS) module containing hollow fibers with a microregular arrangement in which hepatocytes in the extra-fiber space of the module form the organoids by centrifugation that maintain liver-specific functions for at least two months in vitro. In preclinical experiments, a PUF-HALSS was applied to a pig having liver failure. To evaluate the effect of liver regeneration, a PUF- and an LLS-HALSS were applied to a rat having reversible hepatic failure. Each HALSS was effective in supporting liver function, stabilization of general conditions and recovery from liver failure state. These results indicate that these HALSS may be useful to treat liver failure patients until liver transplantation or until regeneration of the native liver.

Animals↗
PubMed2003

[Relationship between the expression of IL-10 and liver regeneration following reduced-size orthotopic liver transplantation in rats].

OBJECTIVES: To explore the relationship between the expression of IL-10 and liver regeneration following reduced-size orthotopic liver transplantation in rats. METHODS: Rats models with reduced-size orthotopic liver transplantation were established. The rats were divided in three groups: partial liver resection (I), orthotopic liver transplantations (II), and reduced-size orthotopic liver transplantation (III). The expression of IL-10 and regenerative response of liver in rats were evaluated by immunohistochemistry and flow cytometry on the 1st, 2nd, 4th and 7th days after the operations, respectively. RESULTS: The liver grafts were capable of regeneration, the proliferation activity peaked on the fourth day with 26.3+/-0.9, 35.8+/-2.2, and 32.4+/-1.8 in I, II, and III groups, respectively. The expression of IL-10 was negative correlation to liver regeneration (r=-0.58, P<0.01). CONCLUSIONS: Whole and reduced-size transplanted livers show the same regenerative activity. The maximal regenerative response delayes slightly, compared with that after partial hepatectomy. IL-10 plays an important immunomodulatory role in liver regeneration,and the effect is affected by general immune system and other cytokines.

Animals↗
PubMed1989

Decreased intramolecular turnover of L-fucose in membrane glycoproteins of rat liver during liver regeneration.

In plasma membrane glycoproteins of rat liver L-fucose undergoes a rapid intramolecular turnover in that fucose residues are removed from the glycoproteins (Tauber, R., Park, C.S. & Reutter, W. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 4026-4029). The present paper demonstrates that the intramolecular turnover of L-fucose is markedly decreased during liver regeneration. Turnover half-lives of L-fucose were measured in regenerating liver by pulse-chase experiments in five plasma membrane glycoproteins (Mr 60,000 (gp60), 80,000 (gp80), 120,000 (gp120), 140,000 (gp140), and 160,000 (gp160). The glycoproteins were isolated from plasma membranes by concanavalin A-Sepharose affinity chromatography and semipreparative NaDodSO4 polyacrylamide gel electrophoresis. L-Fucose turned over in the five glycoproteins with heterogeneous half-lives ranging from 22 h (gp160) to 49 h (gp120). The protein moieties of the glycoproteins were degraded with half-lives ranging from 56 h (gp80) to 107 h (gp140). Relative to the half-life of the protein backbone the half-live of L-fucose was increased in the five membrane glycoproteins by 70% (gp60), 150% (gp80), 182% (gp120), 60% (gp140) and 16% (gp160) during liver regeneration when compared to normal liver. The data show that L-fucose turns over in different membrane glycoproteins with individual rates, and that loss of L-fucose from plasma membrane glycoproteins is reduced in rapidly proliferating liver after partial hepatectomy.

Animals↗
PubMed1983

Effect of autonomic denervation on DNA synthesis during liver regeneration after partial hepatectomy.

The regulatory role of autonomic nerves in liver regeneration after partial hepatectomy was studied in rats by bilateral subdiaphragmatic vagotomy or splanchnicectomy. 1. In control rats the wet weight of the regenerating liver was restored to approximately 80% of the preoperative weight 72 h after partial hepatectomy. Restoration of the liver weight was significantly impaired in vagotomy rats, but not in splanchnicectomy. Increases in the DNA and protein contents of the regenerating liver were also suppressed by vagotomy. 2. Hepatic DNA synthesis, measured as the incorporation of [methyl-3H]thymidine into DNA at various times after partial hepatectomy, was significantly less in vagotomized rats, and slightly more in splanchnicectomized rats than in control rats. The onset of DNA synthesis triggered by partial hepatectomy was also delayed by vagotomy. 3. The increases in activities of hepatic aspartate transcarbamoylase and thymidine kinase, the key enzymes in synthesis of pyrimidine nucleotides via the de novo and salvage pathways respectively, during liver regeneration, were significantly suppressed and retarded in vagotomized rats. Conversely, splanchnicectomy tended to stimulate these enzyme inductions after partial hepatectomy. 4. During starvation the plasma insulin level decreased after partial hapatectomy in control and vagotomized rats, as in sham-operated rats, but showed a transient increase 6 h after partial hepatectomy in splanchnicectomized rats. It is concluded that vagotomy inhibits and delays DNA synthesis and proliferation of liver cells after partial hepatectomy, whereas splanchnicectomy tends to stimulate these processes. The data also suggest that parasympathetic innervation of the liver may play an important regulatory role in liver regeneration.

Animals↗
PubMed1997

[New aspects in the liver regeneration following partial hepatectomy].

We demonstrated the new two concepts for the liver regeneration after partial hepatectomy (PHx). The first is immunological findings in the regenerating liver. Th1 type T cells, which produce IFN gamma, and extrathymic T cells may play an important role in immunological control system of liver regeneration after PHx on the basis of the cellular immunity restricted by MHC class I and II molecules. The second is the mechanism of "on and off" on liver regeneration after PHx. Portal pressure, which reflecting wall shear stress of sinusoid, may trigger the liver regeneration and control the liver volume after PHx. There are two type of intrahepatic leukocytes; one type would tend to stay associated with SEC, while the other would not. Therefore shear stress may have a great influence on the leukocytes-sinusoidal endothelial cells (SEC) adhesion immediately after partial hepatectomy.

Animals↗
PubMed2001

Inhibition by interferon alpha-2b of rat liver regeneration: effect on ornithine decarboxylase and total protein synthesis.

Polyamines are key factors in macromolecule synthesis during liver regeneration. It has been postulated that interferon-alpha (IFNalpha) decreases putrescine levels in regenerating liver by inhibiting ornithine decarboxylase (ODC) activity, the main enzyme in polyamine biosynthesis. In the present study, we analysed the effects of a pharmacological dose of IFNalpha on polyamine and ODC levels during the regenerative process following partial hepatectomy in rats. Synthesis of ODC by isolated hepatocytes from IFN-treated rats with regenerating livers was also assessed. Furthermore, we investigated the effect of IFNalpha-2b on DNA and total protein synthesis in 24-hr regenerating livers. No effect on DNA synthesis was observed at the dose of IFNalpha-2b used, but total protein synthesis decreased significantly in IFNalpha-2b-treated rats undergoing liver regeneration (7.0 +/- 2.0 and 12.1 +/- 1.7%. min(-1) in hepatectomized rats treated with IFNalpha-2b and saline, respectively). ODC levels were also reduced significantly (by 50%) in hepatectomized rats treated with IFNalpha-2b versus saline. In parallel with the ODC decrease, the concentrations of putrescine and spermidine (63 +/- 25 vs 101 +/- 15 nmol/g liver and 1.08 +/- 0.35 vs 2.14 +/- 0.22 micromol/g liver, respectively, in IFNalpha-2b- and saline-treated hepatectomized rats) showed similar, significant diminutions. Moreover, the incorporation of [35S]methionine into ODC was decreased dramatically in isolated hepatocytes from IFNalpha-2b-treated hepatectomized rats 12 hr after surgery. In conclusion, the protein synthesis rate in regenerating liver was impaired by therapeutic doses of IFNalpha-2b. In addition, the results presented in this study suggest that IFNalpha-2b negatively regulates ODC synthesis, causing a reduction in polyamine levels during liver regeneration.

Animals↗
PubMed1996

Assessment of liver regeneration by quantitative MRI analysis.

Liver regeneration after an extensive liver resection is a serious clinical problem, which is difficult to study in detail on patients. Therefore animal models were developed to study liver regeneration. Anabolic processes in the liver were assessed by measurements of the cholinesterase synthesis, and the regeneration of liver mass was monitored by use of magnetic resonance imaging. It has been shown that the liver mass reaches 90% of the control within the first week after the resection of 75% of the liver. This is partly due to the regeneration, and partly to the increased water content of the regenerated liver, shown by the magnetic resonance images. The results allow the conclusion that the magnetic resonance imaging is a reliable method to assess liver regeneration in vivo.

Animals↗
PubMed1991

Transforming growth factor-beta (TGF-beta) isoforms in rat liver regeneration: messenger RNA expression and activation of latent TGF-beta.

Expression of transforming growth factor-beta s (TGF-beta s) 1-3 was studied in normal liver and during liver regeneration after partial hepatectomy in the rat to determine whether each of these isoforms might be involved in hepatocyte growth in vivo. Expression of the mRNAs for all three TGF-beta isoforms increases in the regenerating liver. In addition, the levels of expression of the mRNAs for several extracellular matrix proteins, including fibronectin, vitronectin, laminin, and collagen, also increase in the regenerating liver. Immunohistochemical staining analysis shows a similar distribution of all three TGF-beta s in normal and regenerating liver; however, in both tissues, the level of expression of TGF-beta 1 is 8- to 10-fold higher than that of TGF-beta 2 as determined by sandwich enzyme-linked immunosorbent assay. Expression of all three TGF-beta mRNAs is restricted to liver nonparenchymal cells. Although hepatocytes from normal and regenerating livers do not synthesize TGF-beta, they are sensitive to inhibition of growth by all three TGF-beta isoforms. Hepatocytes from regenerating livers are capable of activating latent TGF-beta 1 complexes in vitro, whereas normal hepatocytes are not. The different TGF-beta isoforms may function in an inhibitory paracrine mechanism that is activated during liver regeneration and may also regulate the synthesis of extracellular matrix components in the regenerating liver.

Animals↗
PubMed2025

Beta-catenin/sirtuin 1/farnesoid X receptor pathway promotion of portal vein ligation and parenchymal transection-induced rapid liver regeneration.

BACKGROUND: By accelerating the regeneration of the future liver remnant, portal vein ligation and parenchymal transection allows for more extensive hepatectomy. Given that the mechanism remains poorly understood, the aim of this study was to investigate the mechanism of portal vein ligation and parenchymal transection-induced liver regeneration. METHODS: A portal vein ligation and parenchymal transection-induced liver regeneration mouse model was established, followed by RNA microarray analysis to identify candidate molecules. Genomic deletion and chemical manipulation of target molecules were used to explore their functions in portal vein ligation and parenchymal transection-induced liver regeneration. Validation was conducted using a diseased liver model and human samples. RESULTS: Portal vein ligation and parenchymal transection-induced liver regeneration was significantly accelerated compared with that in sham-operated mice (P < .05). An RNA microarray revealed that Sirtuin 1 is a crucial molecule in the proliferation of the future liver remnant. Regardless of whether Sirtuin 1 is inhibited chemically or through genetic deletion, portal vein ligation and parenchymal transection-induced liver regeneration is distinctly attenuated. Further investigation revealed that Sirtuin 1 promoted portal vein ligation and parenchymal transection-induced liver regeneration via the farnesoid X receptor. In addition, beta-catenin also was found to participate in the process of future liver remnant proliferation. Chemical inhibition of beta-catenin markedly impaired but activation of WNT/beta-catenin mildly enhanced portal vein ligation and parenchymal transection-induced liver regeneration (P < .05). Deletion of Sirtuin 1 blocked the facilitating effect of beta-catenin on portal vein ligation and parenchymal transection-induced liver regeneration. These findings were validated in diseased liver models and patient samples, confirming the correlation between the beta-catenin/Sirtuin 1/farnesoid X receptor pathway and portal vein ligation and parenchymal transection-induced liver regeneration. CONCLUSION: Activation of the beta-catenin/Sirtuin 1/farnesoid X receptor pathway offers critical mechanistic insights into accelerating portal vein ligation and parenchymal transection-induced liver regeneration. Modulation of beta-catenin/Sirtuin 1/farnesoid X receptor may therefore improve clinical outcomes in patients receiving staged hepatectomy.

Liver Regeneration↗
PubMed2004

Disruption of hepatic adipogenesis is associated with impaired liver regeneration in mice.

The liver responds to injury with regulated tissue regeneration. During early regeneration, the liver accumulates fat. Neither the mechanisms responsible for nor the functional significance of this transient steatosis have been determined. In this study, we examined patterns of gene expression associated with hepatic fat accumulation in regenerating liver and tested the hypothesis that disruption of hepatic fat accumulation would be associated with impaired hepatic regeneration. First, microarray-based gene expression analysis revealed that several genes typically induced during adipocyte differentiation were specifically upregulated in the regenerating liver prior to peak hepatocellular fat accumulation. These observations suggest that hepatic fat accumulation is specifically regulated during liver regeneration. Next, 2 methods were employed to disrupt hepatocellular fat accumulation in the regenerating liver. Because exogenous leptin supplementation reverses hepatic steatosis in leptin-deficient mice, the effects of leptin supplementation on liver regeneration in wild-type mice were examined. The data showed that leptin supplementation resulted in suppression of hepatocellular fat accumulation and impairment of hepatocellular proliferation during liver regeneration. Second, because glucocorticoids regulate cellular fat accumulation during adipocyte differentiation, the effects of hepatocyte-specific disruption of the glucocorticoid receptor were similarly evaluated. The results showed that hepatic fat accumulation and hepatocellular proliferation were also suppressed in mice with liver specific disruption of glucocorticoid receptor. In conclusion, suppression of hepatocellular fat accumulation is associated with impaired hepatocellular proliferation following partial hepatectomy, indicating that hepatocellular fat accumulation is specifically regulated during and may be essential for normal liver regeneration.

Animals↗
PubMed2003

Isolation and analysis of a novel gene over-expressed during liver regeneration.

AIM: To isolate and analyze a novel gene over-expressed during liver regeneration. METHODS: Total RNA of regenerating liver was extracted from liver tissue after 0-4-36-36-36 hr short interval successive partial hepatectomy (SISPH). Reverse transcription-polymerase chain reaction was used to synthesize double strand cDNA, after the tissue was digested by proteinase K and Sfi A/B. The double-strand cDNA was ligated to lambdaTriplEx2. lambdaphage packaging reaction was performed and E. coli XL1-Blue was infected for titering and amplifying. One expressed sequence tag was probed by Dig and phage in situ hybridization was carried out to isolate positive clones. Positive recombinant lambdaTriplEx2 was converted to the corresponding pTriplEx2, and bioinformatics was used to analyze full-length cDNA. RESULTS: We isolated a novel full-length cDNA during liver regeneration following SISPH. CONCLUSION: We have succeeded in cloning a novel gene, based on bioinformatics. We postulate that this gene may function in complicated network in liver regeneration. On the one hand, it may exert initiation of liver regeneration via regulating nitric oxide synthesis. On the other hand, it may protect damaged residue lobus following SISPH.

Amino Acid Sequence↗
PubMed1993

[Effects of medium chain triglyceride administration on liver regeneration after partial hepatectomy in rats].

The influence of lipid emulsion, especially medium chain triglyceride (MCT), on liver regeneration was investigated after 70% hepatectomy in rats. The rats received one of the following 3 solutions as a fuel source in total parenteral nutrition (TPN) regimen: a glucose solution (Group-G), a mixture of long chain triglyceride (LCT) and glucose (Group-L), or a mixture of MCT and glucose (Group-M). The calorie ratio of fat to glucose in LCT and MCT was 1 to 1. The energy charge (EC) of the regenerating liver decreased at 6 or 12 hours after hepatectomy and returned to the pre-operative level at 24 hours in each group. But EC at 6 hours was significantly higher in group-M than in group-G. Lipoperoxide (LPO) in regenerating liver was significantly lower in group-Mand-L than in group-G at 12 hours after hepatectomy, but it was significantly higher in group-M than in group-G and -L at 48 hours. Labeling index (LI) of bromodeoxyuridine (BrdU) was significantly higher in group-Mand L than in group-G at 24 hours after hepatectomy. These results indicate that MCT may be beneficial energy substrates in acute phase of regenerating liver. Although lipid emulsion has beneficial effect on the liver regeneration after hepatectomy, in recovery phase of liver regeneration, addition of LCT with MCT may be considered more beneficial.

Adenine Nucleotides↗
PubMed1995

Expression of cytokine genes during liver regeneration after partial hepatectomy in rats.

In the present study to demonstrate the relationship between cytokines and liver regeneration we investigated by Northern blot hybridization the cytokine gene induction in the regenerating liver and several other organs (spleen, lung, and kidney) in the rat after partial hepatectomy (PH). We also examined whether Kupffer cells and the spleen are involved in the induction of cytokine mRNA in the regenerating liver. Both IL-1 alpha and beta mRNA increased transiently 1/2 to 1 hr after PH in nonparenchymal cells (NPC) of the regenerating liver; they reached a maximum before the peak of hepatocyte DNA synthesis. PH also induced a slight, but significant, gene expression of IL-1 in lung and kidney in the early postoperative period. TNF-alpha mRNA increased gradually in the spleen, but not the liver, of partially hepatectomized rats at 3 to 12 hr and then reached a peak at 24 hr after PH. IL-6 transcripts were not detected in the regenerating liver, spleen, lung, or kidney during liver regeneration. In contrast, no cytokine gene expression was induced in any of these four organs during the first 3 days after sham operation or unilateral nephrectomy. When Kupffer cell activity was suppressed by gadolinium chloride pretreatment, or when splenectomy was performed 24 hr before PH, the constitutive IL-1 alpha and beta mRNA expressions in NPC of the normal rat liver were completely suppressed. In conclusion, the present study demonstrates, for the first time, the specific kinetics of cytokine gene expression in the liver, spleen, lung, and kidney after PH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Molecular cloning of mRNA sequences transiently induced during rat liver regeneration.

In order to isolate genes which are induced during liver regeneration, we have constructed a cDNA library from 16-h-regenerating liver poly(A)+ RNA. By computer analysis of autoradiograms produced by differential plaque hybridization with cDNA from normal or 16-h-regenerating liver, we have isolated several recombinant clones representing sequences transiently increased during liver regeneration. Three of these were further characterized: the level of the corresponding mRNAs increase rapidly after partial hepatectomy, before the onset of DNA synthesis. Two clones were identified as fibrinogen clones. It is speculated that alpha-fibrinogen may be involved in the growth process, or in its regulation.

Animals↗
PubMed2006

Nitric oxide and prostaglandins potentiate the liver regeneration cascade.

The liver has the remarkable ability to regenerate following damage or surgical resection. Although this feature of the liver has been studied for over 100 years, the trigger of the liver regeneration cascade remains controversial. Recent experimental evidence supports the hypothesis that nitric oxide (NO) and prostaglandins (PGs), released secondary to an increase in the blood flow-to-liver mass ratio following two-thirds partial hepatectomy (PHx), work synergistically to trigger liver regeneration. To extend this research, the hypothesis that NO and PGs are potential therapeutic targets to potentiate the liver regeneration cascade is tested. The NO donor s-nitroso-n-acetylpenicillamine, the phosphodiesterase V antagonist zaprinast (ZAP) and PGI2 each potentiated c-fos messenger RNA expression, an index of initiation of the liver regeneration cascade, following PHx. Also, the triple combination of s-nitroso-n-acetylpenicillamine, ZAP and PGI2 potentiated c-fos messenger RNA expression. These results support the hypothesis that NO and PGs can potentiate initiation of the regeneration cascade. An additional index of liver weight restoration 48 h after PHx was also used to test the hypothesis, because this index encompasses the entire liver regeneration cascade. ZAP and 6-keto-PGF1alpha, a stable metabolite of PGI2, and the combination of ZAP and 6-keto-PGF1alpha, each potentiated liver weight restoration 48 h after PHx. These results also provide support for the hypothesis that NO and PGs are possible therapeutic targets to potentiate liver regeneration following surgical resection.

3',5'-Cyclic-GMP Phosphodiesterases↗