tretinoin and Kidney-Diseases

Vitamin A (VA, retinol) and its metabolites (commonly called retinoids) are required for the proper development of the kidney during embryogenesis, but retinoids also play key roles in the function and repair of the kidney in adults. Kidneys filter 180-200 liters of blood per day and each kidney contains approximately 1 million nephrons, which are often referred to as the 'functional units' of the kidney. Each nephron consists of a glomerulus and a series of tubules (proximal tubule, loop of Henle, distal tubule, and collecting duct) surrounded by a network of capillaries. VA is stored in the liver and converted to active metabolites, most notably retinoic acid (RA), which acts as an agonist for the retinoic acid receptors ((RARs α, β, and γ) to regulate gene transcription. In this review we discuss some of the actions of retinoids in the kidney after injury. For example, in an ischemia-reperfusion model in mice, injury-associated loss of proximal tubule (PT) differentiation markers occurs, followed by re-expression of these differentiation markers during PT repair. Notably, healthy proximal tubules express ALDH1a2, the enzyme that metabolizes retinaldehyde to RA, but transiently lose ALDH1a2 expression after injury, while nearby myofibroblasts transiently acquire RA-producing capabilities after injury. These results indicate that RA is important for renal tubular injury repair and that compensatory mechanisms exist for the generation of endogenous RA by other cell types upon proximal tubule injury. ALDH1a2 levels also increase in podocytes, epithelial cells of the glomeruli, after injury, and RA promotes podocyte differentiation. We also review the ability of exogenous, pharmacological doses of RA and receptor selective retinoids to treat numerous kidney diseases, including kidney cancer and diabetic kidney disease, and the emerging genetic evidence for the importance of retinoids and their receptors in maintaining or restoring kidney function after injury. In general, RA has a protective effect on the kidney after various types of injuries (eg. ischemia, cytotoxic actions of chemicals, hyperglycemia related to diabetes). As more research into the actions of each of the three RARs in the kidney is carried out, a greater understanding of the actions of vitamin A is likely to lead to new insights into the pathology of kidney disorders and the development of new therapies for kidney diseases.

Topics: Animals; Kidney; Kidney Diseases; Mice; Retinoids; Tretinoin; Vitamin A

Topics: Animals; Cell Differentiation; Cell Proliferation; Humans; Kidney; Kidney Diseases; Membrane Proteins; Receptors, Retinoic Acid; Signal Transduction; Tretinoin

Erythropoietin (EPO) is a crucial hormone for erythropoiesis and produced by adult kidneys. Insufficient EPO production in chronic kidney disease (CKD) can cause renal anemia. Although hypoxia-inducible factors (HIFs) are known as a main regulator, the mechanisms of EPO production have not been fully elucidated. In this study, we aimed to examine the roles of retinoic acid (RA) in EPO production using EPO-producing cells derived from human induced pluripotent stem cells (hiPSC-EPO cells) that we previously established. RA augmented EPO production by hiPSC-EPO cells under hypoxia or by treatment with prolyl hydroxylase domain-containing protein (PHD) inhibitors that upregulate HIF signals. Combination treatment with RA and a PHD inhibitor improved renal anemia in vitamin A-depleted CKD model mice. Our findings using hiPSC-EPO cells and CKD model mice may contribute to clarifying the EPO production mechanism and developing efficient therapies for renal anemia.

Topics: Anemia; Animals; Basic Helix-Loop-Helix Transcription Factors; Drug Evaluation, Preclinical; Drug Therapy, Combination; Erythropoietin; Glycine; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Hypoxia-Inducible Factor-Proline Dioxygenases; Induced Pluripotent Stem Cells; Isoquinolines; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; Tretinoin

Retinoic acid (RA) activates RA receptors (RAR), resulting in RA response element (RARE)-dependent gene expression in renal collecting duct (CD). Emerging evidence supports a protective role for this activity in acute kidney injury (AKI) and chronic kidney disease (CKD). Herein, we examined this activity in RARE-LacZ transgenic mice and by RARE-Luciferase reporter assays in CD cells, and investigated how this activity responds to neurotransmitters and mediators of kidney injury. In RARE-LacZ mice, Adriamycin-induced heavy albuminuria was associated with reduced RA/RAR activity in CD cells. In cultured CD cells, RA/RAR activity was repressed by acetylcholine, albumin, aldosterone, angiotensin II, high glucose, cisplatin and lipopolysaccharide, but was induced by aristolochic acid I, calcitonin gene-related peptide, endothelin-1, gentamicin, norepinephrine and vasopressin. Compared with age-matched normal human CD cells, CD-derived renal cystic epithelial cells from patients with autosomal recessive polycystic kidney disease (ARPKD) had significantly lower RA/RAR activity. Synthetic RAR agonist RA-568 was more potent than RA in rescuing RA/RAR activity repressed by albumin, high glucose, angiotensin II, aldosterone, cisplatin and lipopolysaccharide. Hence, RA/RAR  in CD cells is a convergence point of regulation by neurotransmitters and mediators of kidney injury, and may be a novel therapeutic target.

Topics: Acetylcholine; Albumins; Aldosterone; Angiotensin II; Animals; Calcitonin Gene-Related Peptide; Cell Line; Cisplatin; Endothelin-1; Female; Glucose; Humans; Kidney Diseases; Kidney Tubules, Collecting; Lipopolysaccharides; Mice; Mice, Transgenic; Receptors, Retinoic Acid; Tretinoin; Vasopressins

The aim of this study is to investigate the effects of all-trans retinoic acid (ATRA) use on cisplatin (CP)-induced nephrotoxicty. Twenty-eight rats were randomly divided into four groups. The rats in the control group were injected a single dose of 1 ml/kg saline intra-peritoneally (IP) during 10 days. The rats in the ATRA group were injected a single dose of ATRA during 10 days. The rats in the ATRA+CP group were injected a single dose of CP on the fourth day of the 10 days of ATRA treatment. The rats in the CP group were injected a single dose of CP on the fourth day of 10 days without administering a treatment. After treatment, the groups were compared with regard to total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) levels in renal tissue and renal histopathology. The serum creatinine and urea values were statistically significantly higher in the CP group compared to the other groups. The serum creatinine and urea values were statistically significantly lower in the ATRA+CP group when compared to the CP group. Although the TOS and OSI levels were found to be lower in the ATRA+CP group compared to the CP group, the difference was not statistically significant. Administration of ATRA together with CP was observed to reduce the histopathologic destruction in the kidney and lead to mild tubular degeneration, vacuolization, and necrosis (57.1% grade 1; 28.6% grade2, and 14.3% grade 3 necrosis). The results of the present study have revealed that ATRA administration ameliorates CP-induced nephrotoxicity; however, further studies are required to identify this issue before clinical application.

Topics: Animals; Antineoplastic Agents; Cisplatin; Kidney; Kidney Diseases; Protective Agents; Rats, Wistar; Tretinoin

Kidney injury is a common complication of severe disease. Here, we report that injuries of the zebrafish embryonal kidney are rapidly repaired by a migratory response in 2-, but not in 1-day-old embryos. Gene expression profiles between these two developmental stages identify cxcl12a and myca as candidates involved in the repair process. Zebrafish embryos with cxcl12a, cxcr4b, or myca deficiency display repair abnormalities, confirming their role in response to injury. In mice with a kidney-specific knockout, Cxcl12 and Myc gene deletions suppress mitochondrial metabolism and glycolysis, and delay the recovery after ischemia/reperfusion injury. Probing these observations in zebrafish reveal that inhibition of glycolysis slows fast migrating cells and delays the repair after injury, but does not affect the slow cell movements during kidney development. Our findings demonstrate that Cxcl12 and Myc facilitate glycolysis to promote fast migratory responses during development and repair, and potentially also during tumor invasion and metastasis.

Topics: Animals; Animals, Genetically Modified; Cell Movement; Chemokine CXCL12; Energy Metabolism; Gene Deletion; Gene Expression Profiling; Gene Expression Regulation, Developmental; Glycolysis; Homeostasis; Kidney; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; Proto-Oncogene Proteins; Signal Transduction; Tretinoin; Zebrafish; Zebrafish Proteins

Cisplatin (cis-diammine dichloroplatinum (II), CDDP) is a widely used drug for treatment of various types of cancers. However, CDDP-induced nephrotoxicity remains the main dose-limiting side effect. Retinoids are a group of vitamin A-related compounds that exert their effects through retinoid receptors activation. In this study, we investigated the effect of CDDP treatment on retinoic acid receptor-α (RAR-α) and retinoid X receptor-α (RXR-α) expression. In addition, we investigated the possible modulatory effects of RAR agonist, all-trans retinoic acid (ATRA), on CDDP-induced nephrotoxicity. Rats were treated with saline, DMSO, CDDP, ATRA, or CDDP/ATRA. Twenty-four hours after the last ATRA injection, rats were killed; blood samples were collected; kidneys were dissected; and biochemical, immunohistochemical, and histological examinations were performed. Our results revealed that CDDP treatment significantly increased serum levels of creatinine and urea, with concomitant decrease in serum albumin. Moreover, reduced glutathione (GSH) content as well as superoxide dismutase (SOD) and catalase (CAT) activities were significantly reduced with concurrent increase in kidney malondialdehyde (MDA) content following CDDP treatment. Furthermore, CDDP markedly upregulated tubular RAR-α, RXR-α, fibrin, and inducible nitric oxide synthase (iNOS) protein expression. Although administration of ATRA to control rats did not produce marked alterations in kidney function parameters, administration of ATRA to CDDP-treated rats significantly exacerbated CDDP-induced nephrotoxicity. In addition, CDDP/ATRA co-treatment significantly increased RAR-α, RXR-α, fibrin, and iNOS protein expression compared to CDDP alone. In conclusion, we report, for the first time, the crucial role of retinoid receptors in CDDP-induced nephrotoxicity. Moreover, our findings indicate that co-administration of ATRA with CDDP, although beneficial on the therapeutic effects, their deleterious effects on the kidney may limit their clinical use.

Topics: Animals; Antineoplastic Agents; Cisplatin; Drug Synergism; Fibrin; Kidney; Kidney Diseases; Male; Nitric Oxide Synthase Type II; Oxidative Stress; Rats; Rats, Sprague-Dawley; Receptors, Retinoic Acid; Retinoic Acid Receptor alpha; Retinoid X Receptors; Signal Transduction; Tretinoin

Topics: Actins; Animals; Collagen Type IV; Disease Models, Animal; Fibronectins; Fibrosis; Kidney; Kidney Diseases; Rats; Transforming Growth Factor beta1; Tretinoin; Ureteral Obstruction

This study was performed to investigate the association of prohibitin with renal interstitial fibrosis (RIF) lesion and to explore the association of all-trans retinoic acid (ATRA) treatment with prohibitin expression in RIF rats. Rats were divided into three groups: the sham operation group (SHO), the model group subjected to unilateral ureteral obstruction (UUO), and the model group treated with ATRA (GA). Renal tissues were collected at 14 and 28 days after surgery, and the relevant indicators were detected. In comparison with the SHO group, the RIF index in the UUO group was markedly elevated (p < 0.01), and the RIF index in the GA group was alleviated compared with that in the UUO group (p < 0.01). Compared with the SHO group, the expression of prohibitin (protein or mRNA) in the UUO group was significantly reduced (each p < 0.01). Prohibitin expression in the GA group was markedly increased when compared with that in the UUO (p < 0.01). The expression of TGF-β1 (protein and mRNA), protein expressions of Col-IV, fibronectin, α-SMA and cleaved Caspase-3, ROS generation and cell apoptosis index in the UUO group were markedly higher than those in the SHO group (all p < 0.01), and their expressions in the GA group were markedly down-regulated compared to those in the UUO group (all p < 0.01, respectively). The protein expression of prohibitin was negatively correlated with the RIF index, protein expression of TGF-β1, Col-IV, fibronectin, α-SMA or cleaved Caspase-3, ROS generation and the cell apoptosis index (each p < 0.01). In conclusion, lower expression of prohibitin is associated with the RIF, and ATRA treatment is associated with increased prohibitin, which can prevent the progression of RIF.

Topics: Actins; Animals; Apoptosis; Caspase 3; Collagen Type IV; Fibronectins; Fibrosis; Gene Expression Regulation; Kidney Diseases; Male; Prohibitins; Rats, Wistar; Reactive Oxygen Species; Repressor Proteins; RNA, Messenger; Transforming Growth Factor beta1; Tretinoin

The authors wish to change Figure 2 of the paper published in IJMS [1]. The positions of H(1) and H(2) in the previous article were reversed. These errors have been amended in an amended version of the manuscript, which is available from the International Journal of Molecular Sciences website. The authors and publisher apologize for the inconvenience. [...].

Topics: Animals; Antineoplastic Agents; Fibrosis; Gene Expression Regulation; Kidney; Kidney Diseases; Prohibitins; Rats; Repressor Proteins; Tretinoin

To examine the effects of all-trans retinoic acid (atRA) on renal morphology and function as well as on renal plasminogen activator inhibitor-1 (PAI-1) expression and plasmin activity in rats with 5/6 nephrectomy.. Adult male Sprague Dawley rats were given 5/6 nephrectomy or sham operation. Renal function was measured 2 weeks later. The nephrectomized rats were assigned to groups matched for proteinuria and treated with vehicle or atRA (5 or 10 mg/kg by gastric gavage once daily) for the next 12 weeks. Rats with sham operation were treated with vehicle. At the end of the treatments, kidneys were collected for histological examination, Western blot analysis, and enzymatic activity measurements.. The 5/6 nephrectomy promoted hypertension, renal dysfunction, and glomerulosclerosis. These changes were significantly reduced in the atRA-treated group. The expressions of PAI-1 and α-smooth muscle actin (α-SMA) were significantly increased in the vehicle-treated nephrectomized rats. Treatment with atRA significantly reduced the expressions of PAI-1 and α-SMA. However, plasmin activity remained unchanged following atRA treatment.. Treatment with atRA ameliorates glomerulosclerosis and improves renal function in rats with 5/6 nephrectomy. This is associated with a decrease in PAI-1 and α-SMA, but not with a change in plasmin activity.

Topics: Actins; Animals; Antineoplastic Agents; Blood Pressure; Body Weight; Fibrinolysin; Gene Expression; Glomerulosclerosis, Focal Segmental; Kidney; Kidney Diseases; Male; Matrix Metalloproteinase 2; Nephrectomy; Plasminogen Activator Inhibitor 1; Rats; Rats, Sprague-Dawley; Tretinoin

Retinoic acids, a group of natural and synthetic vitamin A derivatives, have potent anti-proliferative, anti-inflammatory and anti-fibrotic properties. We investigated the therapeutic effect of all-trans-retinoic acid (ATRA) on unilateral ureteral obstruction (UUO) model mice.. First, to evaluate the prophylactic effect, we administered 0.5 mg of ATRA for 3 days before UUO (UUO ATRA). Then, to evaluate the therapeutic effects, we administered 0.5 mg of ATRA 3 days after UUO (Day 3 ATRA). We compared the histological changes and immunostaining of macrophages, α-smooth muscle actin (α-SMA) and collagen I, and mRNA expression of monocyte chemotactic protein-1 (MCP-1), transforming growth factor (TGF)-β(1) and TGF-β R-II by RT-PCR 7 days after UUO.. In the UUO ATRA and Day 3 ATRA groups, we observed a significant improvement in histological and immunological findings, including macrophage infiltration and improved expression of MCP-1, TGF-β(1), α-SMA and collagen I compared with the UUO Day 7 group.. ATRA treatment is not only an effective prophylactic strategy, but also a therapeutic strategy for the treatment of progressive renal fibrosis in diseased kidneys.

Topics: Actins; Animals; Chemokine CCL2; Collagen Type I; Disease Models, Animal; Female; Fibrosis; Kidney Diseases; Mice; Mice, Inbred C57BL; Receptors, Transforming Growth Factor beta; Transforming Growth Factor beta; Tretinoin; Ureteral Obstruction

The study aimed to predict effective human jejunal permeability (P(eff)) using a biophysical model based on parametrized paracellular, aqueous boundary layer, and transcellular permeabilities, and the villus-fold surface area expansion factor (k(VF)). Published human jejunal data (119 P(eff), 53 compounds) were analyzed by a regression procedure incorporating a dual-pore size paracellular model. Transcellular permeability, scaled by k(VF), was equated to that of Caco-2 at pH 6.5. The biophysical model predicted human jejunal permeability data within the experimental uncertainty. This investigation revealed several surprising predictions: (i) many molecules permeate predominantly (but not exclusively) by the paracellular route, (ii) the aqueous boundary layer thickness in the intestinal perfusion experiments is larger than expected, (iii) the mucosal surface area in awake humans is apparently nearly entirely accessible to drug absorption, and (iv) the relative "leakiness" of the human jejunum is not so different from that observed in a number of published Caco-2 studies.

Topics: Animals; Disease Models, Animal; Dogs; Humans; Jejunal Diseases; Kidney Diseases; Models, Biological; Permeability; Porosity; Regression Analysis

Nephron number varies widely between 0.3 and 1.3 million per kidney in humans. During fetal life, the rate of nephrogenesis is influenced by local retinoic acid (RA) level such that even moderate maternal vitamin A deficiency limits the final nephron number in rodents. Inactivation of genes in the RA pathway causes renal agenesis in mice; however, the impact of retinoids on human kidney development is unknown. To resolve this, we tested for associations between variants of genes involved in RA metabolism (ALDH1A2, CYP26A1, and CYP26B1) and kidney size among normal newborns. Homozygosity for a common (1 in 5) variant, rs7169289(G), within an Sp1 transcription factor motif of the ALDH1A2 gene, showed a significant 22% increase in newborn kidney volume when adjusted for body surface area. Infants bearing this allele had higher umbilical cord blood RA levels compared to those with homozygous wild-type ALDH1A2 rs7169289(A) alleles. Furthermore, the effect of the rs7169289(G) variant was evident in subgroups with or without a previously reported hypomorphic RET 1476(A) proto-oncogene allele that is critical in determining final nephron number. As maternal vitamin A deficiency is widespread in developing countries and may compromise availability of retinol for fetal RA synthesis, our study suggests that the ALDH1A2 rs7169289(G) variant might be protective for such individuals.

Topics: Alleles; Cytochrome P-450 Enzyme System; Developing Countries; Genotype; Humans; Infant; Infant, Newborn; Kidney; Kidney Diseases; Nephrons; Organogenesis; Oxidoreductases; Proto-Oncogene Mas; Proto-Oncogenes; Retinoic Acid 4-Hydroxylase; Retinoids; Tretinoin; Vitamin A; Vitamin A Deficiency

Matrix gamma-carboxyglutamic acid protein (MGP), a vitamin K-dependent protein, is involved in regulation of tissue calcification. We previously reported that 9-cis retinoic acid (RA) mitigates 1alpha,25-dihydroxycholecalciferol [1,25(OH)(2)D3]-induced renal calcification in a 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung cancer A/J male mouse model. This raised the question if the mechanism(s) underlying this calcification involves vitamin K. We assessed expression and vitamin K dependent gamma-carboxylation of MGP and vitamin K concentrations [phylloquinone (PK), as well as its conversion product, menaquinone-4 (MK-4)] in tissues obtained from NNK-injected A/J male mice fed 1,25(OH)(2)D3 (2.5 microg/kg diet; D group) +/- RA (15 mg/kg diet) for 20 wk. Renal calcification was only observed in the D group (2/10; 20% of the group). Renal MGP mRNA and uncarboxylated MGP (ucMGP) increased in response to D (P < 0.05) but not in response to RA or RA + D. In contrast, gamma-carboxylated MGP increased to 2.2-fold of the control in response to D+RA (P < 0.05) but not in response to RA or D alone. Although all diets contained equal amounts of PK, the kidney MK-4 concentration was higher in the D group (P < 0.05) and lower in the RA group (P < 0.05) compared with the RA+D or control groups. Renal PK concentrations were lower in the RA and RA+D groups than in the control and D groups (P < 0.05). These data suggest that 9-cis RA mitigated 1,25(OH)(2)D3-induced renal calcification by modifying the 1,25(OH)(2)D3-induced increase in ucMGP. The mechanisms by which 9-cis RA and 1,25(OH)(2)D3 alter vitamin K concentrations warrant further investigation.

Topics: Alitretinoin; Animals; Base Sequence; Calcinosis; Calcitriol; Calcium-Binding Proteins; Carbon-Carbon Ligases; Carcinogens; Dietary Supplements; DNA Primers; Extracellular Matrix Proteins; Kidney Diseases; Liver; Male; Matrix Gla Protein; Mice; Mice, Inbred A; Nitrosamines; RNA, Messenger; Tretinoin; Vitamin K

Topics: Drug Administration Schedule; Humans; Kidney Diseases; Leukemia, Promyelocytic, Acute; Male; Middle Aged; Remission Induction; Tretinoin

Bone marrow transplant nephropathy (BMTN) classically presents more than 100 days after transplantation as an acute nephritis with hypertension, azotaemia and anemia that usually results in end stage renal failure (ESRF). The risk of developing BMTN may be greater with the use of more intensive chemotherapy and higher total body and tumor bed irradiation. Cis-retinoic acid (RA) may further increase the risk of developing BMTN. Here, we report the cases of two children who developed typical clinical and biochemical features of BMTN. They were both treated for stage IV neuroblastoma with chemotherapy, bone marrow transplant (BMT) conditioning that included total body irradiation and RA therapy after BMT, although the patient in case 1 had established renal insufficiency prior to the commencement of RA. Renal biopsy of these children showed classical BMTN histology, and the renal manifestations progressed quickly; the patient in case 1 became dialysis dependent by 1 year post-bone marrow transplant. Recently, RA has been added to the post-BMT therapy in children with stage IV neuroblastoma. The occurrence of BMTN in two children treated with RA in our unit is unlikely to be coincidental. Although RA has been shown to confer a significant survival advantage in this disease, animal studies and a previous case report have suggested it could increase the toxic effects of chemotherapy and renal irradiation. It is likely that RA contributed to the deterioration in renal function in these patients.

Topics: Antineoplastic Agents; Bone Marrow Transplantation; Child, Preschool; Female; Humans; Kidney; Kidney Diseases; Male; Neoplasm Staging; Neuroblastoma; Postoperative Care; Stereoisomerism; Tretinoin

Studies have shown that angiotensin-converting enzyme inhibitors and an angiotensin II receptor blocker can delay, but cannot reverse, the progression of experimentally induced radiation nephropathy. In an effort to find a method for reversing injury, three agents were tested in a rat model of radiation nephropathy. Pirfenidone (a phenyl-pyridone antifibrotic) and thiaproline (an inhibitor of collagen deposition) were not capable of retarding the development of radiation nephropathy. However, all-trans retinoic acid (an anti-inflammatory agent) exacerbated radiation nephropathy. We speculated that the detrimental effects of retinoic acid might be the result of stimulation of renal cell proliferation. However, retinoic acid had no effect on tubular or glomerular cell proliferation in normal animals and did not enhance radiation-induced proliferation. A recent report that retinoic acids inhibit nitric oxide production suggested an alternative mechanism, since inhibition of production of nitric oxide is known to exacerbate radiation nephropathy. Experiments demonstrated that retinoic acid exacerbated the radiation-induced drop in renal production of nitric oxide, suggesting that the detrimental effect of all-trans retinoic acid might be explained by inhibition of renal nitric oxide activity. Particularly in view of the recent clinical report of enhancement of radiation nephropathy by retinoic acid in patients receiving bone marrow transplantation, the combination of retinoic acid and renal irradiation should be carried out with great caution.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cell Division; Extracellular Matrix; Fibrosis; Hypertension, Renal; Kidney; Kidney Diseases; Kidney Failure, Chronic; Proteinuria; Pyridones; Radiation Injuries, Experimental; Rats; Rats, Inbred Strains; Thiazoles; Thiazolidines; Tretinoin; Uremia; Whole-Body Irradiation

A 22-year-old female presented with acute promyelocytic leukemia (APL). Treatment with all-trans retinoic acid (ATRA) resulted in a severe exacerbation of the coagulopathy 5 days after its introduction. This was complicated by bone marrow necrosis, parenchymal liver damage and acute tubular necrosis. Temporary cessation of the drug and subsequent dose reduction was effective in controlling the coagulopathy.

Topics: Adult; Antineoplastic Agents; Blood Coagulation Disorders; Bone Marrow; Chemical and Drug Induced Liver Injury; Female; Humans; Kidney Diseases; Leukemia, Promyelocytic, Acute; Liver Diseases; Necrosis; Tretinoin