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Biomedical subjects

G Bellomo

Publications and source records attributed to G Bellomo.

At least 37 records · Page 2Linked to original sources
PubMed1999

The HMG protein T160 colocalizes with DNA replication foci and is down-regulated during cell differentiation.

The high mobility group protein T160, the murine homolog of the human structure-specific recognition protein 1, was first supposed to be involved in the process of V-(D)-J recombination, since it could bind to recombination signal sequence probes. We have recently cloned T160 by using an unrelated DNA probe and shown that it binds to either cruciform or linear DNA with no sequence specificity. In this work, we performed a detailed analysis of T160 expression and immunolocalization. We show that T160 is a phosphoprotein broadly conserved from yeast to mammals, with a high level of expression in all the cell lines tested and in tissues containing a high degree of proliferating cells. Indirect immunofluorescence analysis by confocal laser microscopy revealed that T160 distribution in the cell nucleus is not uniform, and focus-like staining was observed. Cell cycle studies by BrdU incorporation suggest that the appearance of T160 nuclear foci is specific of mid to late S phase. Furthermore, while T160 expression does not change during the cell cycle, it is dramatically down-regulated when cells begin to differentiate, as highlighted in C2C12 myoblasts and myotubes. The disappearance of T160 nuclear staining in multinucleated myotubes is shown. Taken together, these data suggest that its function may be less specific than V-(D)-J recombination and more related to some cellular basic process, such as DNA replication or repair.

Amino Acid Sequence↗
PubMed1999

Intracellular Na+ accumulation and hepatocyte injury during cold storage.

BACKGROUND: The mechanisms responsible for liver damage during cold storage are still not completely understood. We have investigated the role played by alterations of Na+ homeostasis in cell injury during cold hypoxia. METHODS: The changes in Na+ distribution were investigated in isolated rat hepatocytes stored at 4 degrees C under hypoxic conditions. RESULTS: Hepatocyte cold stored up to 72 hr in Krebs-Henseleit-Hepes buffer showed a progressive increase in intracellular Na+ content that preceded the loss of cell viability. Na+ accumulation and cell death were prevented using Na+-free, acidic (pH 6.5) or glycine-supplemented storage media. The Na+ ionophore monensin reverted the cytoprotection exerted by glycine and by the acidic medium, but not that given by Na+-free Krebs-Henseleit-Hepes. A low Na+ content was also important for the cytoprotection observed using University of Wisconsin solution. CONCLUSIONS: Na+ overload might contribute to liver graft injury occurring during cold storage.

Adenosine↗
PubMed1999

When and why a water-soluble antioxidant becomes pro-oxidant during copper-induced low-density lipoprotein oxidation: a study using uric acid.

The inclusion of uric acid in the incubation medium during copper-induced low-density lipoprotein (LDL) oxidation exerted either an antioxidant or pro-oxidant effect. The pro-oxidant effect, as mirrored by an enhanced formation of conjugated dienes, lipid peroxides, thiobarbituric acid-reactive substances and increase in negative charge, occurred when uric acid was added late during the inhibitory or lag phase and during the subsequent extensive propagation phase of copper-stimulated LDL oxidation. The pro-oxidant effect of uric acid was specific for copper-induced LDL oxidation and required the presence of copper as either Cu(I) or Cu(II). In addition, it became much more evident when the copper to LDL molar ratio was below a threshold value of approx. 50. In native LDL, the shift between the antioxidant and the pro-oxidant activities was related to the availability of lipid hydroperoxides formed during the early phases of copper-promoted LDL oxidation. The artificial enrichment of isolated LDL with alpha-tocopherol delayed the onset of the pro-oxidant activity of uric acid and also decreased the rate of stimulated lipid peroxidation. However, previous depletion of alpha-tocopherol was not a prerequisite for unmasking the pro-oxidant activity of uric acid, since this became apparent even when alpha-tocopherol was still present in significant amounts (more than 50% of the original values) in LDL. These results suggest, irrespective of the levels of endogenous alpha-tocopherol, that uric acid may enhance LDL oxidation by reducing Cu(II) to Cu(I), thus making more Cu(I) available for subsequent radical decomposition of lipid peroxides and propagation reactions.

Amidines↗
PubMed1999

Alterations of cell volume regulation in the development of hepatocyte necrosis.

Intracellular Na+ accumulation has been shown to contribute to hepatocyte death caused by anoxia or oxidative stress. In this study we have investigated the mechanism by which Na+ overload can contribute to the development of cytotoxicity. ATP depletion in isolated hepatocytes exposed to menadione-induced oxidative stress or to KCN was followed by Na+ accumulation, loss of intracellular K+, and cell swelling. Hepatocyte swelling occurred in two phases: a small amplitude swelling (about 15% of the initial size) with preservation of plasma membrane integrity and a terminal large amplitude swelling associated with cell death. Inhibition of Na+ accumulation by the use of a Na+-free medium prevented K+ loss, cell swelling, and cytotoxicity. Conversely, blocking K+ efflux by the addition of BaCl2 did not influence Na+ increase and small amplitude swelling, but greatly stimulated large amplitude swelling and cytotoxicity. Menadione or KCN killing of hepatocytes was also enhanced by inducing cell swelling in an hypotonic medium. However, increasing the osmolarity of the incubation medium did not protect against large amplitude swelling and cytotoxicity, since stimulated Na+ accumulation and K+ efflux. Altogether these results indicate that the impairment of volume regulation in response to the osmotic load caused by Na+ accumulation is critical for the development of cell necrosis induced by mitochondrial inhibition or oxidative stress.

Animals↗
PubMed1999

Serum ferritin and hepatic glutathione concentrations in chronic hepatitis C patients related to the hepatitis C virus genotype.

BACKGROUND/AIMS: Increased serum ferritin is thought to be responsible for activation of glutathione turnover in patients with chronic hepatitis C. The aim of the study was to evaluate a possible correlation between levels of serum ferritin and concentrations of hepatic, plasmatic and lymphocytic glutathione in a selected cohort of chronic hepatitis C patients in relation to the hepatitis C virus genotype. METHODS: The study considered 130 chronic hepatitis C patients and 23 control subjects. Hepatic glutathione was determined from biopsy liver specimens by high performance liquid chromatography. Total Iron Score was assessed by scoring iron separately within hepatocytes, sinusoidal cells and portal tracts. Blood samples were tested for determination of serum ferritin, and plasmatic and lymphocytic glutathione levels. Hepatic and erythocyte malonyldialdehyde were also determined along with peripheral blood mononuclear cell cytotoxic assay. RESULTS: Patients with genotype 1b showed higher levels of serum ferritin compared to patients with genotype 2a/2c and 3a and to controls, along with a significant reduction of the concentrations of hepatic, plasmatic and lymphocytic glutathione and peripheral blood mononuclear cell cytotoxic activity. The levels of serum ferritin correlated significantly to Total Iron Score, to hepatic, plasmatic and lymphocytic glutathione, to hepatic and erythrocyte malonyldialdehyde and to peripheral blood mononuclear cell cytotoxic activity. CONCLUSIONS: The levels of serum ferritin correlate significantly to lipoperoxidation markers in chronic hepatitis C patients. The increased production of free radicals with a reduced peripheral blood mononuclear cell cytotoxic activity may represent, especially in patients with genotype 1b, a factor underlying the resistance to interferon therapy and may influence the evolution of the liver disease by enhancement of the cytopathic effect of hepatitis C virus.

Adult↗
PubMed1999

4-Hydroxynonenal as a biological signal: molecular basis and pathophysiological implications.

Reactive oxygen intermediates (ROI) and other pro-oxidant agents are known to elicit, in vivo and in vitro, oxidative decomposition of omega-3 and omega-6 polyunsaturated fatty acids of membrane phospholipids (i.e, lipid peroxidation). This leads to the formation of a complex mixture of aldehydic end-products, including malonyldialdehyde (MDA), 4-hydroxy-2,3-nonenal (HNE), and other 4-hydroxy-2,3-alkenals (HAKs) of different chain length. These aldehydic molecules have been considered originally as ultimate mediators of toxic effects elicited by oxidative stress occurring in biological material. Experimental and clinical evidence coming from different laboratories now suggests that HNE and HAKs can also act as bioactive molecules in either physiological and pathological conditions. These aldehydic compounds can affect and modulate, at very low and nontoxic concentrations, several cell functions, including signal transduction, gene expression, cell proliferation, and, more generally, the response of the target cell(s). In this review article, we would like to offer an up-to-date review on this particular aspect of oxidative stress--dependent modulation of cellular functions-as well as to offer comments on the related pathophysiological implications, with special reference to human conditions of disease.

Aldehydes↗
PubMed1999

Circulating antibodies recognizing oxidatively modified low-density lipoprotein in children.

The occurrence of circulating antibodies (IgG) against oxidatively modified LDL was investigated in a group of normocholesterolemic, healthy, cardiovascular risk-free children and in a comparable group of normal adults. An increased titer of IgG recognizing Cu++-oxidized or malondialdehyde (MDA)-derivatized LDL (MDA-LDL) was a constant feature in children. The antigenic epitopes recognized by these antibodies were generated rather late in the process of copper-mediated LDL oxidation, concomitantly with the formation of fluorescent adducts between reactive aldehydes (including MDA) and apo B100. MDA-LDL was not the only antigen recognized: derivatization of other structurally unrelated proteins, such as HDL, serum albumin, fibrinogen, and transferrin with MDA led to generation of recognizable epitopes. However, among the various modified proteins, LDL exhibited the highest binding activity for IgG present in the group of children. This was associated with an enhanced propensity of LDL isolated from children to undergo in vitro oxidation, despite normal levels of the endogenous antioxidant alpha-tocopherol. These findings indicate that circulating antibodies recognizing proteins modified with end-products of lipid peroxidation (including LDL) are present in healthy cardiovascular risk-free children. The possibility that LDL oxidation occurs in vivo already in childhood and may act as the real immunogen is an attractive but still unproven hypothesis.

Adolescent↗
PubMed1999

[Hypersplenism: current status and perspectives].

The hypersplenism is a syndrome characterized by cytopenia (involving one or several cellular lines of peripheral blood), increased or normal medullar cellularity, elevated turnover of the involved cellular line. Several studies have emphasized the important role of the spleen as an immunocompetent organ, with a microcirculation and typical functional characteristics. The authors attempt to assess relations between the hypersplenism and splenomegaly, as well as indications, risks and complications of splenectomy in pathological conditions. Finally, the alternative procedures to splenectomy are described.

Administration, Cutaneous↗
PubMed1999

Total intravenous anesthesia with propofol and remifentanil for elective non-cardiac surgery.

BACKGROUND: Remifentanil is a highly effective mu opioid agonist with predictable pharmacokinetics and a close concentration-effect relationship. Moreover, studies on anesthetic drugs interactions show that optimal propofol concentrations decrease more significantly with remifentanil as compared with other opioids and recovery appears to be much faster than when propofol is combined with other opioids combinations. This intervention study was designed to evaluate the efficacy of propofol combined with remifentanil in elective non cardiac inpatient surgery. METHODS: N. 405 patients undergoing intraperitoneal, head-neck, intrathoracic, major orthopaedics, breast and major vascular surgery received: remifentanil (1 microgram.kg-1 at induction; 0.50 microgram.kg-1.min-1 at laryngoscopy; 0.25 microgram.kg-1.min-1 at skin incision; 0.25-0.30 microgram.kg-1.min1 from skin incision to end of skin suture) and propofol (0.5-1 mg.kg-1 at induction; 5 mg.kg-1.h-1 at laryngoscopy; 5 mg.kg-1.h-1 at skin incision and 5 mg.kg1.h1 thereafter). Intraoperative end-points included somatic responses, tachycardia and hypertension to laryngoscopy and surgery. Incidence of intraoperative bradycardia, hypotension and muscle rigidity were also recorded. Postoperative end-points included Aldrete score > or = 9, pain immediately following emergence and PONV. RESULTS: Propofol-remifentanil combination effectively controlled responses to laryngoscopy and surgical stress. Drug related adverse events were transient bradycardia (< 50 bpm) and hypotension (SBP < or = 80 mmHg) respectively: at prelaryngoscopy 11.60-1.48% and at pre-skin incision 10.61-0.98%. N. 365 patients were discharged from PACU and the median time to first Aldrete score > or = 9 was 22.3 min. The most frequent postoperative event was shivering recorded in n. 46 patients (12%). Postoperative analgesic medication was requested by n. 16 patients (4.4%) and PONV was noted in n. 6 patients (1.6%). CONCLUSIONS: When combined with propofol, remifentanil effectively provided for profound analgesia during surgery, stable anesthetic conditions, simplicity of use and predictable recovery.

Anesthesia, Intravenous↗
PubMed1998

Cu(I) availability paradoxically antagonizes antioxidant consumption and lipid peroxidation during the initiation phase of copper-induced LDL oxidation.

The incubation of isolated human low-density lipoprotein (LDL) with Cu(II) promoted extensive oxidation of both the lipid and protein moieties of the lipoprotein particle. When the Cu(II) to LDL molar ratio was equal or higher than 50, the removal of Cu(I) formed by the contemporary presence of the Cu(I) chelator bathocuproine disulphonate (BC) markedly accelerated the formation of end-products of lipid peroxidation. Moreover, the initial rate of Cu(II)-induced consumption of either endogenous antioxidants in LDL or free alpha-tocopherol in suspension was increased in the presence of BC, thus indicating that the continuous removal of Cu(I) enhanced both antioxidant consumption and LDL oxidation promoted by copper. Furthermore, the direct addition of Cu(I), together with Cu(II), to a suspension of isolated LDL efficiently delayed the onset of extensive lipid peroxidation and decreased the rate of antioxidant consumption. The latter effect, however, was detectable exclusively on LDL-associated alpha-tocopherol and not on alpha-tocopherol in suspension, thus suggesting that the competition between Cu(I) and Cu(II) was taking place at discrete sites associated with the LDL particle. Finally, the inclusion of Cu(I) in the incubation medium of LDL already undergoing extensive peroxidation did not inhibit but rather markedly stimulated the rate of peroxidation. Although apparently in contrast with the common view that Cu(I) and not Cu(II) is the real trigger species of LDL oxidation in the copper model, the results reported here indicate that the availability of Cu(I) during the initiation phase of LDL oxidation promoted by copper antagonizes both antioxidant consumption and the onset of extensive oxidation.

Adult↗
PubMed1998

HNE interacts directly with JNK isoforms in human hepatic stellate cells.

4-Hydroxy-2,3-nonenal (HNE) is an aldehydic end product of lipid peroxidation which has been detected in vivo in clinical and experimental conditions of chronic liver damage. HNE has been shown to stimulate procollagen type I gene expression and synthesis in human hepatic stellate cells (hHSC) which are known to play a key role in liver fibrosis. In this study we investigated the molecular mechanisms underlying HNE actions in cultured hHSC. HNE, at doses compatible with those detected in vivo, lead to an early generation of nuclear HNE-protein adducts of 46, 54, and 66 kD, respectively, as revealed by using a monoclonal antibody specific for HNE-histidine adducts. This observation is related to the lack of crucial HNE-metabolizing enzymatic activities in hHSC. Kinetics of appearance of these nuclear adducts suggested translocation of cytosolic proteins. The p46 and p54 isoforms of c-Jun amino-terminal kinase (JNKs) were identified as HNE targets and were activated by this aldehyde. A biphasic increase in AP-1 DNA binding activity, associated with increased mRNA levels of c-jun, was also observed in response to HNE. HNE did not affect the Ras/ERK pathway, c-fos expression, DNA synthesis, or NF-kappaB binding. This study identifies a novel mechanism linking oxidative stress to nuclear signaling in hHSC. This mechanism is not based on redox sensors and is stimulated by concentrations of HNE compatible with those detected in vivo, and thus may be relevant during chronic liver diseases.

Aldehydes↗
PubMed1998

Free radical-scavenging properties of olive oil polyphenols.

Plants in the Mediterranean basin, such as vine and olive trees, have developed an array of antioxidant defences to protect themselves from environmental stress. Accordingly, the incidence of coronary heart disease and certain cancers is lower in the Mediterranean area, where olive oil is the dietary fat of choice. As opposed to other vegetable oils, extra virgin olive oil, which is obtained by physical pressure from a whole fruit, is rich in phenolic components that are responsible for the particular stability of the oil. We have investigated the scavenging actions of some olive oil phenolics, namely hydroxytyrosol and oleuropein, with respect to superoxide anion generation, neutrophils respiratory burst, and hypochlorous acid. The low EC50S indicate that both compounds are potent scavengers of superoxide radicals and inhibitors of neutrophils respiratory burst: whenever demonstrated in vivo, these properties may partially explain the observed lower incidence of CHD and cancer associated with the Mediterranean diet.

Antioxidants↗
PubMed1998

GAS6 inhibits granulocyte adhesion to endothelial cells.

GAS6 is a ligand for the tyrosine kinase receptors Rse, Axl, and Mer, but its function is poorly understood. Previous studies reported that both GAS6 and Axl are expressed by vascular endothelial cells (EC), which play a key role in leukocyte extravasation into tissues during inflammation through adhesive interactions with these cells. The aim of this work was to evaluate the GAS6 effect on the adhesive function of EC. Treatment of EC with GAS6 significantly inhibited adhesion of polymorphonuclear cells (PMN) induced by phorbol 12-myristate 13-acetate (PMA), platelet-activating factor (PAF), thrombin, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), but not that induced by FMLP and IL-8. GAS6 did not affect adhesion to resting EC. Titration experiments showed that high concentrations of GAS6 were needed to inhibit PMN adhesion and that inhibition was dose-dependent at the concentration range of 0.1 to 1 microg/mL. One possibility was that high concentrations were needed to overwhelm the effect of endogenous GAS6 produced by EC. In line with this possibility, treatment of resting EC with soluble Axl significantly potentiated PMN adhesion. Analysis of localization of GAS6 by confocal microscopy and cytofluorimetric analysis showed that it is concentrated along the plasma membrane in resting EC and treatment with PAF induces depletion and/or redistribution of the molecule. These data suggest that GAS6 functions as a physiologic antiinflammatory agent produced by resting EC and depleted when proinflammatory stimuli turn on the proadhesive machinery of EC.

Cell Adhesion↗
PubMed1998

Inhibition of cell proliferation by the interferon-inducible 204 gene, a member of the Ifi 200 cluster.

The role of the IFN-inducible p204 as growth regulator was investigated by transfecting an expression vector constitutively expressing p204 into several cell lines. Like pRB and p107, p204 is a potent growth inhibitor in sensitive cells, as demonstrated by the cell focus assay. Since stable transfectants of sensitive lines constitutively overexpressing p204 could not be established in vitro, we inserted the 204 cDNA into a vector bearing an heavy-metal-inducible promoter. Here we show that proliferation of B6MEF fibroblasts lacking endogenous p204 is strongly inhibited by transient p204 expression in the nucleus. p204 delays G1 progression into the S-phase and cells accumulate with a DNA content equivalent to cells arrested in late G1. Moreover, the role of p204 in the control of cell growth in vivo was investigated by generating transgenic mice in which the Ifi 204 gene was constitutively expressed in all tissues. To this end, expression vectors bearing the 204 cDNA under the control of the SV40 viral promoter were constructed. The overexpression of the p204 transgene achieved by injecting fertilized mouse eggs with these vectors was compatible with embryo development up to the four-cell stage in an in vitro follow-up of 4.5 days. However, no viable animals with an intact copy of the transgene were obtained, suggesting that high and constitutive levels of p204 expression can impair normal embryo development. These findings indicate that p204 plays a negative role in growth regulation and provide new information about the molecular mechanisms exploited by IFNs to inhibit cell proliferation.

Animals↗
PubMed1998

Increased levels of the soluble adhesion molecule E-selectin in patients with chronic myeloproliferative disorders and thromboembolic complications.

Patients with chronic myeloproliferative disorders (CMD) show a high frequency of thrombosis. For this reason we evaluated endothelial cell markers, soluble adhesion molecule E-selectin (sELAM), and thrombomodulin (TM) in 25 patients with CMD. Among them nine presented thromboses in their past history. Data were compared with those obtained in a group of healthy subjects and a group of patients with secondary thrombocytosis. The mean plasma concentrations of sELAM were elevated in patients with CMD, as compared with healthy subjects (81.27 +/- 42.8 ng/ml vs. 41.75 +/- 13; P < 0.02). Similarly, the mean plasma concentrations of sTM were increased in CMD patients in comparison with the control group (102.0 +/- 73 ng/ml vs. 16.7 +/- 9.6; P < 0.01). More markedly elevated sELAM levels were observed in CMD patients with thrombosis than in patients without thrombosis (113.16 +/- 29.5 ng/ml vs. 55.11 +/- 19.1 ng/ml; P < 0.001), while no significant difference was found between CMD patients without thrombosis and secondary thrombocytosis (50.72 +/- 10.8 ng/ml). Plasma thrombomodulin values in CMD patients with thrombosis (131 +/- 93.8 ng/ml) were higher than those without thrombosis (65.77 +/- 43.9 ng/ml; P < 0.02). sTM values were also significantly increased in patients with secondary thrombocytosis (P < 0.01). It is speculated that the plasma, sELAM levels may reflect endothelium activation and that it is possibly useful in predicting the thrombotic risk in myeloproliferative disorders.

Adult↗
PubMed1998

Flumazenil for hepatic encephalopathy grade III and IVa in patients with cirrhosis: an Italian multicenter double-blind, placebo-controlled, cross-over study.

The rationale for use of benzodiazepine receptor antagonists is based on the so-called benzodiazepine pathogenetic hypothesis of hepatic encephalopathy (HE). To assess the efficacy of flumazenil, a specific benzodiazepine receptor antagonist, in a large and selected population of cirrhotic patients with severe HE, we conducted a double-blind, placebo-controlled, cross-over trial on 527 cirrhotic patients with HE grade III and IVa admitted to Intensive Care Units over a 5-year period; among them, 265 (132 of grade III and 133 of grade IVa) received flumazenil, whereas 262 (130 of grade III and 132 of grade IVa) received placebo. Treatment was begun within 15 minutes of randomization; the response to treatment was assessed by neurological score and by continuous electroencephalographic (EEG) recordings. Improvement of the neurological score was documented in 17.5% of grade III patients treated with flumazenil and in 14.7% of grade IVa patients, compared, respectively, with 3.8% and 2.7% of the patients of both groups treated with placebo. Improvements in EEG tracings were observed in 27.8% of grade III patients and in 21.5% of grade IVa patients, compared, respectively, with 5% and 3.3% of the patients of both groups treated with placebo. Benzodiazepines were detected in the serum of 10 patients (4 in grade III group and 6 in grade IVa group). Flumazenil is beneficial only in a selected subset of cirrhotic patients with severe HE; the applicability of this treatment to unselected patients with severe HE still remains to be determined.

Adult↗