Signaling pathways involved in isoprostane-mediated fibrogenic effects in rat hepatic stellate cells.

Despite evidence supporting a potential role for F2-isoprostanes (F2-IsoP's) in liver fibrosis, their signaling mechanisms are poorly understood. We have previously provided evidence that F2-IsoP's stimulate hepatic stellate cell (HSC) proliferation and collagen hyperproduction by activation of a modified form of isoprostane receptor homologous to the classic thromboxane receptor (TP). In this paper, we examined which signal transduction pathways are set into motion by F2-IsoP's to exert their fibrogenic effects.

Ethanol-induced oxidative stress: basic knowledge.

After a general introduction, the main pathways of ethanol metabolism (alcohol dehydrogenase, catalase, coupling of catalase with NADPH oxidase and microsomal ethanol-oxidizing system) are shortly reviewed. The cytochrome P(450) isoform (CYP2E1) specifically involved in ethanol oxidation is discussed. The acetaldehyde metabolism and the shift of the NAD/NADH ratio in the cellular environment (reductive stress) are stressed.

Oxidative stress, isoprostanes and hepatic fibrosis.

An introduction to oxidative stress enlightening the spreading of interest in lipid peroxidation in the 60's and in the identification of cytotoxic aldehydes originating from it is given. The discovery of F2-isoprostanes as specific markers of oxidative stress is described. Isoprostanes are also agonists of important biological effects.

Systemic oxidative stress in classic Rett syndrome.

Rett syndrome (RS), a progressive severe neurodevelopmental disorder mainly caused by de novo mutations in the X-chromosomal MeCP2 gene encoding the transcriptional regulator methyl-CpG-binding protein 2, is a leading cause of mental retardation with autistic features in females. However, its pathogenesis remains incompletely understood, and no effective therapy is available to date. We hypothesized that a systemic oxidative stress may play a key role in the pathogenesis of classic RS.

Free iron, total F-isoprostanes and total F-neuroprostanes in a model of neonatal hypoxic-ischemic encephalopathy: neuroprotective effect of melatonin.

Oxidative stress due to free radical formation and initiation of abnormal oxidative reactions is involved in several diseases of newborns, such as hypoxic-ischemic encephalopathy. Melatonin, an endogenously produced indoleamine primarily formed in the pineal gland, is a potent free radical scavenger as well as an indirect antioxidant. The present study was conducted to evaluate the formation of oxidative damage mediators and the possible effect of melatonin treatment in a model of hypoxic-ischemic encephalopathy in 7-day-old rats.

Effects of weight loss on liver and erythrocyte polyunsaturated fatty acid pattern and oxidative stress status in obese patients with non-alcoholic fatty liver disease.

Our aim was to study the influence of weight loss on the fatty acid (FA) composition of liver and erythrocyte phospholipids and oxidative stress status in obese, non-alcoholic, fatty liver disease (NAFLD) patients. Seven obese NAFLD patients who underwent subtotal gastrectomy with a gastro-jejunal anastomosis in roux and Y were studied immediately and 3 months after surgery. Seven non-obese patients who underwent anti-reflux surgery constituted the control group.

Oxidative stress, erythrocyte ageing and plasma non-protein-bound iron in diabetic patients.

Increased oxidative stress and decreased life span of erythrocytes (RBCs) are repeatedly reported in diabetes. In the aim to elucidate the mechanism of the latter, i.e.

Plasma esterified F2-isoprostanes and oxidative stress in newborns: role of nonprotein-bound iron.

Nonprotein-bound iron (NPBI) and F2-isoprostanes, reliable markers of oxidative stress, are increased in plasma of newborns and inversely correlated to the gestational age. Because NPBI represents a pro-oxidant stimulus in plasma, we test the hypothesis that the entity of lipid peroxidation is related with NPBI concentrations. Plasma levels of free, esterified, and total F2-isoprostanes were investigated in relation to NPBI levels in 59 newborns and 16 healthy adults.

F2-isoprostane receptors on hepatic stellate cells.

F2-isoprostanes are considered as the most reliable markers of oxidative stress and can be used to evaluate the oxidative status in a number of human pathologies. Besides being markers of oxidative stress, F2-isoprostanes proved to be mediators of important biological effects and would act through the activation of receptors analogous to those for thromboxane A2. In a previous work, we provided evidence that F(2)-isoprostanes, generated during carbon tetrachloride-induced hepatic fibrosis, mediate hepatic stellate cell (HSC) proliferation and collagen hyperproduction.

Isoprostanes and hepatic fibrosis.

After a brief introduction to oxidative stress, the discovery of F(2)-isoprostanes as specific and reliable markers of oxidative stress is described. Isoprostanes are also agonists of important biological effects. Since a relation between oxidative stress and collagen hyperproduction has been previously suggested and since lipid peroxidation products have been proposed as possible mediators of liver fibrosis, we investigated whether collagen synthesis is induced by F(2)-isoprostanes the most proximal products of lipid peroxidation.

F2-isoprostanes are not just markers of oxidative stress.

F(2)-isoprostanes are not just markers of oxidative stress. The discovery of F(2)-isoprostanes (F(2)-IsoPs) as specific and reliable markers of oxidative stress in vivo is briefly summarized here. F(2)-IsoPs are also agonists of important biological effects, such as the vasoconstriction of renal glomerular arterioles, the retinal vessel, and the brain microcirculature.

Polyunsaturated fatty acid pattern in liver and erythrocyte phospholipids from obese patients.

Objective: Our aim was to study the fatty acid (FA) composition of liver phospholipids and its relation to that in erythrocyte membranes from patients with obese nonalcoholic fatty liver disease (NAFLD), as an indication of lipid metabolism alterations leading to steatosis.

Research Methods And Procedures: Eight control subjects who underwent antireflux surgery and 12 obese patients with NAFLD who underwent subtotal gastrectomy with a gastro-jejunal anastomosis in Roux-en-Y were studied. The oxidative stress status of patients was assessed by serum F2-isoprostanes levels (gas chromatography/negative ion chemical ionization tandem mass spectrometry).

Oxidative stress and autologous immunoglobulin G binding to band 3 dimers in newborn erythrocytes.

Since birth-induced oxidative stress (OS) results in the removal of erythrocytes from the blood stream, we studied the binding of autologous IgG to erythrocyte band 3 dimers (the 170-kDa band, which marks the erythrocytes for removal) in preterm and term newborns and in adults. The 170-kDa band was present in as much as 74% of preterm, in 21% of term newborns, and in 10% of adults. During erythrocyte ageing "in vitro" (0, 24, and 48 h aerobic incubation), the appearance of the band occurred much faster with erythrocytes from newborns (particularly preterm) than with those from adults.

F2-isoprostanes stimulate collagen synthesis in activated hepatic stellate cells: a link with liver fibrosis?

Carbon tetrachloride (CCl4)-induced hepatic fibrosis has been considered to be linked to oxidative stress and mediated by aldehydic lipid peroxidation products. In the present study, we investigated whether collagen synthesis is induced by F2-isoprostanes, the most proximal products of lipid peroxidation and known mediators of important biological effects. By contrast with aldehydes, F2-isoprostanes act through receptors able to elicit definite signal transduction pathways.

Plasma F2-isoprostanes are elevated in newborns and inversely correlated to gestational age.

F(2)-isoprostanes, prostaglandin F(2)-like compounds formed by free radical-catalyzed lipid peroxidation, are considered the most reliable markers of oxidative stress. It has been repeatedly suggested that newborns are exposed to conditions of oxidative stress resulting from the change from a low oxygen pressure in utero to a high oxygen pressure at birth. We measured the levels of F(2)-isoprostanes in plasma of newborns by gas chromatography/mass spectrometry and we found that F(2)-isoprostanes are significantly higher in term newborns compared to healthy adults.

Iron release, superoxide production and binding of autologous IgG to band 3 dimers in newborn and adult erythrocytes exposed to hypoxia and hypoxia-reoxygenation.

Iron is released in a desferrioxamine (DFO)-chelatable form when erythrocytes are challenged by an oxidative stress. The release is increased when an accelerated removal of erythrocytes occurs such as in perinatal period, in which iron release is greater in hypoxic than in non-hypoxic newborns. This suggests that an hypoxic environment at birth promotes iron release.

Cisplatin-induced apoptosis in melanoma cells: role of caspase-3 and caspase-7 in Apaf-1 proteolytic cleavage and in execution of the degradative phases.

Apoptosis protease-activating factor-1 (Apaf-1), which plays a central role in the formation of the apoptosome, is absent or poorly expressed (because of a transcriptional silencing by methylation) in a substantial percentage of metastatic melanomas and melanoma cell lines, which are unable to activate caspase-9 and execute the mitochondrial pathway of apoptosis. We studied cisplatin-induced apoptosis of the Apaf-1-positive human metastatic Me665/2/21 melanoma cells. Our results indicate that caspase-7 is already processed in still-adhering cells and such activation, contrary to the common view, precedes caspase-3 processing.

Role of caspases-3 and -7 in Apaf-1 proteolytic cleavage and degradation events during cisplatin-induced apoptosis in melanoma cells.

Apoptosis protease-activating factor-1 (Apaf-1), the central element in the mitochondrial pathway of apoptosis, is frequently absent or poorly expressed in metastatic melanomas, a tumor type showing a low degree of spontaneous apoptosis and a poor response to conventional therapies. In the present study, we used the Apaf-1-positive Me665/2/21 melanoma cell line to investigate the fate of Apaf-1 during cisplatin-induced apoptosis. As novel findings described for the first time in melanoma cells, we observed that Apaf-1 was markedly decreased during apoptosis, already at early stages of cell damage; concurrently, an immunoreactive N-terminal fragment of congruent with 26 kDa was evident.

Redox modulation of NF-kappaB nuclear translocation and DNA binding in metastatic melanoma. The role of endogenous and gamma-glutamyl transferase-dependent oxidative stress.

Aims And Background: The transcription factor NF-kappaB is implicated in the expression of genes involved in cell proliferation, apoptosis and metastasis. In melanoma, high constitutive levels of NF-kappaB activation are usually observed. NF-kappaB is regulated by oxidation/reduction (redox) processes, and the occurrence of constitutive oxidative stress in melanoma cells has been documented.

Ion trap tandem mass spectrometric determination of F2-isoprostanes.

A new tandem mass spectrometry (MS/MS) method based on the use of an ion trap mass spectrometer for the identification and quantitation of F(2)-isoprostanes has been developed. It consists of two solid-phase extractions and two derivation steps followed by gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI-MS/MS) analysis. This method is highly selective and sensitive and it has been successfully applied to biological samples.

Possible role of membrane gamma-glutamyltransferase activity in the facilitation of transferrin-dependent and -independent iron uptake by cancer cells.

BACKGROUND: The molecular mechanisms by which iron is physiologically transported trough the cellular membranes are still only partially understood. Several studies indicate that a reduction step of ferric iron to ferrous is necessary, both in the case of transferrin-mediated and transferrin-independent iron uptake. Recent studies from our laboratory described gamma-glutamyltransferase activity (GGT) as a factor capable to effect iron reduction in the cell microenvironment.

Redox modulation of protein kinase/phosphatase balance in melanoma cells: the role of endogenous and gamma-glutamyltransferase-dependent H2O2 production.

Alterations of protein kinase and protein phosphatase activities have been described in a number of tumors. Redox changes, such as in conditions of oxidant stress, have been reported to affect the cellular protein kinase/phosphatase balance. A basal production of reactive oxygen species (ROS), such as hydrogen peroxide (H(2)O(2)), exists in tumor cells, and the membrane-bound ecto-enzyme gamma-glutamyltransferase (GGT)-overexpressed in a variety of malignant tumors-is one of the mechanisms capable of promoting such a production.

Iron release in erythrocytes and plasma non protein-bound iron in hypoxic and non hypoxic newborns.

Iron is released in a desferrioxamine (DFO)-chelatable form (DCI) when erythrocytes are challenged by an oxidative stress. In beta-thalassemic erythrocytes, both DCI content and release (after aerobic incubation for 24h) are increased and correlated with the fetal hemoglobin (HbF) levels. Since erythrocytes from newborns have an extremely high content of HbF and are exposed to conditions of oxidative stress, the release of iron in these erythrocytes was investigated.

Effect of free iron on collagen synthesis, cell proliferation and MMP-2 expression in rat hepatic stellate cells.

Various studies on hepatic fibrosis occurring in iron overload suggest that excess of tissue iron may be involved in the stimulation of collagen synthesis. Anyway, up to date, direct evidence on the role of iron in hepatic fibrosis is lacking. Moreover, it is not clear whether iron acts as direct initiator of fibrogenesis or as mediator of hepatocellular necrosis.