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.

Prognostic value of 24-hour blood pressure in pregnancy

CONTEXT

Elevated blood pressure (BP) measured at the physician's office may reflect true hypertension or white coat hypertension (WCH). The prognostic value of WCH among pregnant women is unknown.

OBJECTIVE

To assess the prognostic value of WCH in pregnancy.

DESIGN

Prospective cohort study conducted between September 1994 and October 1997.

SETTING

Community hospital.

PATIENTS

Women without preexisting hypertension and not treated with antihypertensive drugs aid with high (n = 148) or normal (n = 106) office BP (high office BP was defined as > or =140 mm Hg systolic and/or > or =90 mm Hg diastolic) matched for gestational age during their third trimester of pregnancy. All women underwent 24-hour noninvasive BP monitoring, and women without hypertension on 24-hour monitoring (125/74 mm Hg or less for average 24-hour BP) with office hypertension were classified as having WCH. Women were followed up through the end of pregnancy.

MAIN OUTCOME MEASURES

Duration of pregnancy, gestational hypertension, preeclampsia or eclampsia, cesarean delivery, placental and neonatal weight, and length of maternal and neonatal hospital stays for those with and without elevated office BP.

RESULTS

After application of exclusion criteria, data for 7 women were removed from the analysis. For the remaining subjects, in the group with elevated BP, prevalence of WCH was 29.2% (42/144). Duration of pregnancy was similar in the normotensive and WCH groups (39.6 vs 39.8 weeks; P = .50), but shorter (38.3 weeks; P<.001) in the true hypertension group. Incidence of preeclampsia was similar in the normotensive and WCH groups (5.8% vs 7.1 %; P = .86) but higher in the true hypertension group (61.7%; P<.001). Frequency of cesarean delivery was lower in the normotensive (12.4%) than in the WCH (45.2%; P = .008) and true hypertension (41.1 %; P = .009) groups. Neonatal weight was lower (P<.001) in the true hypertension (mean, 2911 g) than in the normotensive (3336 g) and WCH groups (3435 g), which did not differ (P = .68). The duration of neonatal hospital stay did not differ between the normotensive and the WCH group (5.3 vs 6.9 days; P = .13) but was longer in the true hypertension group (12.3 days; P<.001).

CONCLUSIONS

In women with elevated BP during their third trimester of pregnancy, 24-hour BP was superior to office BP (distinguishing true hypertension from WCH) for prediction of the outcome of pregnancy. Outcomes in the normotensive and WCH group were comparable, but the increased incidence of cesarean delivery in the WCH group may reflect decision-making processes influenced by office BP.

[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.

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.

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.

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.

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.

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.

Neonatal and maternal levels of lipid-soluble antioxidants

Lipid peroxidation plays an important role in the pathogenesis of several neonatal complications. To improve the knowledge on the antioxidant lipid-soluble defenses in neonatal age, we investigated a group of healthy full-term infants and their mothers measuring by high-pressure liquid chromatography the levels of vitamin E and carotenoids. Our data demonstrate that neonatal levels of lipid-soluble anti-oxidants are lower than the maternal ones. Moreover we show that neonatal Vitamin E and carotenoid concentrations are respectively unrelated and strictly related to maternal levels of the same lipid-soluble anti-oxidants.

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.

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.

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.

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.

Interferon-alpha-2B and ribavirin in combination for chronic hepatitis C patients not responding to interferon-alpha alone: an Italian multicenter, randomized, controlled, clinical study

OBJECTIVE

The aim of the study was to assess the efficacy of interferon (IFN)-alpha-2b and ribavirin in combination in the treatment of chronic hepatitis C (CHC) patients unresponsive to a previous treatment with IFN-alpha-2b alone.

METHODS

We conducted a randomized study in 303 CHC patients. One hundred fifty-two patients received subcutaneous administration of recombinant IFN-alpha-2b (3 MU thrice weekly) and ribavirin (1000-1200 mg/daily per os), whereas 151 received IFN-alpha-2b alone (6 MU thrice weekly). Both ribavirin and IFN-alpha-2b were given for 24 wk, regardless of treatment response. Alanine aminotransferase (ALT) levels and HCV RNA titer were checked during the treatment period and for a further 24 wk.

RESULTS

Normal ALT levels were observed in 64.5% of the patients treated with IFN-alpha and ribavirin and in 22.6% of the patients treated with IFN-alpha alone. In the group of patients receiving IFN-alpha and ribavirin HCV RNA was not detectable in 40% of patients responders and remained undetectable in 44.2% of sustained responders. In the group of patients receiving IFN-alpha alone HCV RNA was not detectable in 24.2% of patients responders and remained not detectable in 33.3% of sustained responders.

CONCLUSIONS

A 24-wk treatment course with IFN-alpha and ribavirin given to patients with a previous lack of response to IFN-alpha alone offers a chance of a sustained biochemical and virological response, at least in a subset of such patients. The role of long-term therapy in inducing prolonged remission still remains to be explored.

Different mechanisms are progressively recruited to promote Cu(II) reduction by isolated human low-density lipoprotein undergoing oxidation

The kinetics of Cu(II) reduction and its relationship to the process of low density lipoprotein (LDL) oxidation were investigated in isolated human LDL incubated with CuSO4 by using the Cu(I) chelator and indicator dye bathocuproine disulfonate (BC). The inclusion of BC in the incubation medium containing isolated LDL and different concentrations of CuSO4 revealed a biphasic kinetics of Cu(II) reduction consisting of an early phase followed by a plateau phase and a subsequent extensive reduction phase. The amount of Cu(I) formed during the early phase, as well as the rate of its generation, were strictly dependent on both the level of Cu(II) available (saturation was observed at 20 and 50 microM CuSO4) and the concentration of alpha-tocopherol within native LDL particles. Artificial enrichment of LDL with different concentrations of alpha-tocopherol led to a parallel increase of both the amount of Cu(II) reduced and the rate of reduction. The late phase of Cu(II) reduction was strictly related to the availability of copper but was largely independent from alpha-tocopherol. Neither the amount of Cu(I) generated nor the rate of generation were saturated at concentrations of copper up to 100 microM. Comparable results were obtained by adding BC at different time-points to the LDL-copper mixture, in order to measure at the same time-points both the true rate of Cu(II) reduction and the generation of TBARS during the dynamic process of LDL oxidation. The rate of Cu(II) reduction was already high during the lag-phase of the LDL oxidation profile and progressively decreased as alpha-tocopherol concentration decreased. The subsequent increase in the rate of Cu(II) reduction paralleled the formation of TBARS during the extensive LDL oxidation phase. These results suggest that different mechanisms of Cu(II) reduction, namely alpha-tocopherol-dependent and independent (likely lipid peroxide-dependent), are progressively recruited during copper-promoted LDL oxidation.

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.

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.

Flumazenil for hepatic coma in patients with liver cirrhosis: an Italian multicentre double-blind, placebo-controlled, crossover study

Several factors suggest that endogenous benzodiazepines and gamma-amino-butyric acid may be involved in pathophysiology of hepatic encephalopathy (HE). Contrasting opinions exist on the therapeutic efficacy of flumazenil in the treatment of HE. This study was planned to assess the efficacy of flumazenil by a double-blind, placebo-controlled, crossover design in a large and selected population of cirrhotic patients in stage 4a HE admitted to intensive care units over a 4-year period. Out of 236 patients selected for the study, 132 received flumazenil, whereas 131 patients received placebo. Improvement of the neurological score was documented in 31 patients (23%) of flumazenil group and in two patients (1.5%) of placebo group (p < 0.001) during the first study period, whereas during the crossover period, improvement of the neurological score was documented in seven patients (5.3%) of the flumazenil group and in none of the placebo group (p = 0.022). Improvements in EEG tracings were observed in 44 patients (33.3%) of flumazenil group and in five patients (3.8%) of placebo group (p < 0.001) during the first study period; during the crossover period, improvements in EEG tracings were observed in 10 patients (7.5%) of the flumazenil group and in two patients (1.5%) of the placebo group (p = 0.040). The presence of benzodiazepines was detected in the serum of three responders and in two non-responders. The presence of diazepam and NN-desmethyl diazepam was documented in two responders; prior intake of synthetic diazepam was later confirmed in these patients. The results of our study suggest that flumazenil is beneficial only in a selected subset of cirrhotic patients with severe HE; the applicability of this treatment to unselected patients with hepatic coma or to cirrhotic patients with less severe HE still remains to be determined.

The effects of thyroid hormone modulation on rat liver injury associated with ischemia-reperfusion and cold storage

We investigated the effects of thyroid hormone modulation on liver injury associated with ischemia-reperfusion (I-R) and cold storage in rats. First, euthyroid and thyroxine (T4)-pretreated rats were exposed in vivo to 20-min global liver ischemia, then 30-min reperfusion. Liver injury was assessed by measuring serum alanine aminotransferase (ALT) levels. Liver concentrations of adenine nucleotides, reduced glutathione (GSH), and oxidized glutathione were evaluated. Second, rats were given the antithyroid drug propylthiouracil (PTU). Livers stored at 0-1 degrees C in Euro-Collins' solution for 20 h were reperfused at 37 degrees C for 15 min. Lactate dehydrogenase (LDH) in the effluent perfusate and bile flow were evaluated during reperfusion. Serum ALT levels increased after ischemia and I-R. ALT increased significantly more in T4-pretreated than in euthyroid rats after ischemia and I-R. Preischemic levels of adenosine triphosphate (ATP) were significantly lower in livers from T4-pretreated than in euthyroid rats (6.22 +/- 0.7 and 11 +/- 0.9 nmol/mg protein, respectively; P < 0.05). After ischemia, liver ATP was similarly reduced in T4-pretreated and euthyroid rats. After reperfusion, ATP partially recovered in euthyroid rats but remained low in T4-pretreated rats (6.7 +/- 1.0 and 1.91 +/- 0.7 nmol/mg protein, respectively; P < 0.05). Preischemic levels of liver GSH decreased to 44% in T4-pretreated rats. After ischemia, GSH decreased similarly in euthyroid and T4-pretreated rats. GSH recovered promptly after reperfusion in euthyroid rats but remained low in T4-pretreated rats (13.9 +/- 3.3 and 3.9 +/- 0.9 nmol/mg protein, respectively; P < 0.02). During reperfusion after cold storage, LDH in effluent perfusate was significantly lower and bile flow higher in livers from PTU-pretreated rats than from euthyroid rats. The histopathological changes observed after I-R and cold storage confirmed the biochemical findings. Our results suggest that T4 administration exacerbates pretransplant liver damage by increasing liver susceptibility to I-R, whereas PTU administration reduces the liver injury associated with cold storage.

IMPLICATIONS

We studied the effects of thyroid hormone modulation on liver injury associated with ischemia-reperfusion and cold storage in rats. Thyroxine administration increased susceptibility to ischemia-reperfusion injury, whereas the antithyroid agent propylthiouracil reduced the deleterious effects associated with cold storage.

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.

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.

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.

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.

In search of biological markers of high-risk carotid artery atherosclerotic plaque: enhanced LDL oxidation

The oxidation of low density lipoprotein (LDL) is a key event in the development and progression of atherosclerosis because it generates molecular epitopes that are more atherogenic than parent LDL. We found previously that patients with carotid atherosclerosis have a significantly higher titer of autoantibodies against oxidatively modified LDL than normal subjects. The aim of this study is to correlate biological markers of in vivo LDL oxidation with the degree of carotid stenosis and of plaque ulceration (PU) in a series of patients undergoing carotid endoarteriectomy (CEA). Ninety-four consecutive patients (68M and 26F, aged 67.3 +/- 8.2 years) who underwent CEA at our institution between June 1993 and January 1994 were included in the study. The degree of carotid stenosis and the presence and extent of PU were correlated with the level of autoantibodies (IgG) against oxidatively modified LDL (Cu++-oxidized [oxLDL] or malondialdehyde derivatized LDL [MDA-LDL]), that consistently mirrors the occurrence of oxidative modifications in vivo. A statistically significant correlation (r = 0.23, p = 0.039) was found between the degree of carotid stenosis and antiMDA-LDL specific ratio (a parameter that describes the specificity of LDL towards other proteins as target for oxidative modification). A statistically significant correlation was also found between the PU score and antioxLDL IgG (r = 0.32, p = 0.011), antiMDA-LDL IgG (r = 0.25, p = 0.045) and antiMDA-LDL IgG specific ratio (r = 0.38, p = 0.002). None of the classical biochemical parameters (total, LDL and HDL cholesterol and triglycerides) correlated with the above-mentioned plaque characteristics. The results shown, support the use of biological markers of in vivo LDL oxidation (antioxidatively modified LDL autoantibody titers) to evaluate the clinical setting of high-risk carotid atherosclerosis both in screening and in follow-up studies.

Soluble integrin ligands and growth factors independently rescue neuroblastoma cells from apoptosis under nonadherent conditions

We have investigated the role of extracellular matrix (ECM) and growth factors in the survival of nonadherent human neuroblastoma cells (line SK-N-BE). Cells cultured in serum-free medium under nonadherent conditions died with apoptotic-like features (chromatin condensation and nuclear fragmentation). SK-N-BE cells underwent neuronal differentiation in response to retinoic acid (RA). While RA itself did not induce apoptosis, differentiation increased the susceptibility of SK-N-BE cells to detachment-induced apoptosis. The appearance of the apoptotic-like phenotype required the maintenance in suspension of SK-N-BE cells for at least 16 h (12.43 +/- 1.40% of cells undergoing apoptosis) and the percentage increased up to 46.84 +/- 3.15% after 24 h. Suspension-induced apoptosis did not depend on increased intracellular Ca2+ levels nor on de novo protein synthesis and was not associated with extensive DNA degradation. Stimulation by soluble collagen I rescued suspended cells from apoptosis, even in the absence of cell adhesion and spreading. The survival promoting effect of ECM was mediated by the integrin receptors, since (1) the protective effect of soluble collagen I was blocked by anti-integrin antibodies to beta 1 and alpha 1 subunits and (2) the antibody-induced clustering of alpha 1, alpha 3, alpha v, beta 1, and beta 3 integrins rescued SK-N-BE cells cultured in suspension from apoptosis. As expected, adhesion on immobilized ECM proteins, collagen I, or laminin (0.1 to 10 micrograms/ml) also rescued SK-N-BE cells from apoptosis in a dose-dependent manner. The de novo protein synthesis was required to promote the survival effect of ECM, since cycloheximide completely abolished the protective effect of collagen I and protection from apoptosis by ECM or by anti-beta 1 antibody was associated with the increased expression of bcl-2. In addition to integrin stimulation, serum, insulin, and nerve growth factor inhibited suspension-induced apoptosis of SK-N-BE cells. The survival effect of serum and growth factors did not require the synthesis of new proteins, unlike the ECM effect. These data show that matrix proteins can promote cell survival in neuronal cells via integrin receptors. This effect does not require cell adhesion and the subsequent changes in cell shape as it can be mediated by soluble integrin ligands in suspended cells and involves a signaling pathway different from that triggered by growth factors.

Vagal system impairment in human immunodeficiency virus-positive patients with chronic hepatitis C: does hepatic glutathione deficiency have a pathogenetic role?

BACKGROUND

Both an autonomic impairment and a systemic depletion of reduced glutathione (GSH) may be documented in patients with chronic liver diseases and in human immunodeficiency virus (HIV)-positive patients.

METHODS

The coefficients of electrocardiographic R-R interval variation (CVc) were assessed in 125 patients with chronic hepatitis C (CHC) (65 HIV-positive and 60 HIV-negative) and in 61 healthy controls. The CVc values were correlated with hepatic (H-GSH), plasmatic (P-GSH), lymphocyte (L-GSH), and erythrocyte (E-GSH) concentrations of GSH and with erythrocyte malonyldialdehyde (MDA) levels.

RESULTS

Compared with healthy controls, in CHC patients the concentrations of H-GSH, P-GSH, L-GSH, and E-GSH were reduced, whereas MDA levels were increased with a statistically significant difference (P < 0.001). CVc was significantly reduced in patients with CHC (especially in those who were HIV-positive) and correlated significantly with the values of H-GSH, P-GSH, L-GSH, E-GSH, and MDA (P < 0.001).

CONCLUSIONS

A dysfunction of the cardiac vagal system may be detected in patients with CHC (especially in those who are HIV-positive); this abnormality may be related to a reduced response to oxidative stress because of a systemic depletion of GSH.

Detection of cytochrome P4503A (CYP3A) in human hepatic stellate cells

In this study we have investigated the occurrence of cytochrome P450 isoforms and of related cytochrome P450 reductase in human hepatic stellate cells (hHSC), a type of cell having relevant roles in physiopathological conditions of the liver. By performing immunoblotting of hHSC microsomes and immunofluorescence analysis associated to confocal laser microscopy we detected only P450 enzymes belonging to the cytochrome P450 3A subfamily (CYP3A) as well as cytochrome P450 reductase. The presence of CYP3A was further indicated by detection of testosterone 6beta-hydroxylase activity in hHSC microsomes. Other important human P450 forms were either undetectable (CYP1A2, CYP2E1, CYP2C8/9/19 and CYP4A) or bearly detectable (CYP1A1) in hHSC. This is the first study showing existence of active cytochrome P450 isoforms in human HSC.

The dynamic reduction of Cu(II) to Cu(I) and not Cu(I) availability is a sufficient trigger for low density lipoprotein oxidation

Copper (II) is one of the most widely employed experimental models to induce in vitro low density lipoprotein (LDL) oxidation. It is generally assumed that Cu(I), generated from active reduction of Cu(II), is the real trigger for the peroxidation of polyunsaturated fatty acids in LDL. We have employed isolated human LDL challenged with Cu(II) and the Cu(I) chelator bathocuproine disulfonic acid (BC) to test the validity of this hypothesis. At lower Cu(II)/LDL molar ratios, BC completely inhibited copper-mediated LDL oxidation evaluated either as thiobarbituric acid reactive substances (TBARS) production or changes in apo B100 electrophoretic mobility. On the contrary, at higher Cu(II)/LDL molar ratios, BC did not prevent LDL oxidation but rather markedly stimulated both the generation of TBARS and the increase of apo B100 electronegativity. These oxidative modifications were completely prevented by the Cu(II) chelator EDTA. Furthermore, the BC-Cu(I) complex alone was neither redox active nor active inducer of TBARS generation. These findings indicate that, under these experimental conditions, [1] Cu(I) is not necessary to promote LDL oxidation, [2] the availability of Cu(II) is a prerequisite and [3] some of the reaction(s) involved in Cu(II) reduction may play an essential role in initiating LDL oxidation.

Suitability of chemical in vitro models to investigate LDL oxidation: study with different initiating conditions in native and alpha-tocopherol-supplemented LDL

Isolated human LDL, used in the native form or supplemented with alpha-tocopherol (alpha T), were oxidized with Cu2+, 2,2'-azobis-(2-amidino propane) hydrochloride (AAPH), and H2O2 plus horseradish peroxidase (HRP). The oxidation kinetics were measured spectrophotometrically at 234 nm to follow the formation of conjugated dienes and evaluated as resistance to oxidation (lag phase, LP) and maximal oxidation rate (propagation rate, PR). The duration of LP in nonsupplemented LDL was different with the three prooxidant stimuli (LP, in min: 96 +/- 19 for Cu2+, 28.7 +/- 6.7 for HRP, and 67.1 +/- 11.2 for AAPH). No correlation was found between the values obtained with Cu2+ and AAPH or HRP, but a significant correlation was found with AAPH and HRP (r = 0.798, P < 0.002). In vitro alpha T supplementation prolonged the LP and decreased the PR with all the stimuli. The extent of increase in LP was highly correlated (r = 0.872, P < 0.001 for Cu2+ and HRP; r = 0.603, P < 0.03 for Cu2+ and AAPH; r = 0.749, P < 0.005 for AAPH and HRP). Although the evaluation of ex vivo LDL oxidation is dependent on the prooxidant stimulus, the three prooxidant conditions used detect equally well the efficiency of alpha T supplementation in preventing LDL oxidation.

Glycine protects against hepatocyte killing by KCN or hypoxia by preventing intracellular Na+ overload in the rat

Glycine has been shown to prevent hepatocyte death induced by anoxia and by several toxic agents. However, the mechanisms responsible for such a cytoprotective effect have not yet been entirely clarified. We have previously shown that an uncontrolled increase in intracellular Na+ is critical for hepatocyte killing induced by adenosine triphosphate (ATP) depletion. We herein report that protection by glycine (2 mmol/L) against cytotoxicity induced in isolated rat hepatocyte by potassium cyanide (KCN) or hypoxia was associated with the prevention of cytosolic Na+ accumulation. The addition of the Na+ ionophore, monensin, abolished the effects of glycine on both Na+ increase and cytotoxicity. Pretreating hepatocytes with the glycine-receptor antagonist, strychnine (1 mmol/L), similarly prevented Na+ overload and cell killing. Glycine at high concentrations and strychnine are known to block Cl- channels in many cell types. Consistently, we have observed that glycine and strychnine prevented the increase of intracellular Cl- levels caused by hypoxia or KCN. Incubation of hepatocytes in a Cl(-)-free medium, obtained by substituting chloride with membrane-impermeable gluconate, significantly reduced Na+ accumulation and cell killing triggered by hypoxia or KCN. Both these effects were abolished by the addition of monensin. The cytoprotective action exerted by hepatocyte incubation in the Cl(-)-free medium was, however, lost when membrane-permeable nitrate, which allowed Na+ accumulation, was used instead to replace chloride. Altogether, these results indicate that glycine inhibition of Cl- conductance protects against hepatocyte killing induced by KCN and hypoxia by interfering with intracellular Na+ accumulation triggered by ATP depletion.

Plasma membrane hydroxyethyl radical adducts cause antibody-dependent cytotoxicity in rat hepatocytes exposed to alcohol

BACKGROUND & AIMS

We reported previously that patients with alcoholic liver disease (ALD) have circulating immunoglobulins reacting with cytochrome P4502E1 (CYP2E1) complexed with hydroxyethyl free radicals. The aim of this study was to investigate whether hydroxyethyl radical adducts are present on the plasma membranes of ethanol-treated hepatocytes and their role in antibody-dependent cytotoxicity.

METHODS

Immunofluorescence confocal laser microscopy, Western blotting, and antibody-dependent cell-mediated cytotoxicity assay were used.

RESULTS

Isolated rat hepatocytes incubated in vitro with ethanol or obtained from ethanol-treated animals showed strong surface fluorescence when exposed to rabbit anti-hydroxyethyl radical serum or sera from patients with ALD. No surface fluorescence was evident on control hepatocytes or after scavenging hydroxyethyl radicals with 4-pyridyl-1-oxide-t-butyl nitrone. The presence of CYP2E1-hydroxyethyl radical adducts on hepatocyte plasma membranes was shown by Western blot and by immunofluorescence using double staining for human and rabbit anti-CYP2E1 immunoglobulin G. Cytotoxicity was observed in ethanol-treated hepatocytes incubated with immunoglobulin G from patients with ALD and normal human blood mononuclear cells. This effect was blocked by preabsorbing the sera with human albumin complexed with hydroxyethyl radicals, which also eliminated the antibody reaction with the plasma membranes.

CONCLUSIONS

Hydroxyethyl radicals bound to CYP2E1 on hepatocyte plasma membranes can target immune reactions triggered by alcohol abuse.

Reduction of oxidative stress does not affect recovery of myocardial function: warm continuous versus cold intermittent blood cardioplegia

OBJECTIVE

To compare oxidative stress after cardiac surgery in patients treated with two different methods of myocardial protection: warm continuous versus cold intermittent blood cardioplegia. To correlate oxidative stress with postoperative myocardial dysfunction.

DESIGN

Prospective, randomised, double blind, trial.

SETTING

Institutional centre of cardiovascular surgery.

PATIENTS

20 patients were selected for coronary artery bypass surgery (CABG) on the following basis: stable angina, ejection fraction > 50%, double or triple vessel disease, no previous CABG or associated disease. Patients were randomised to two groups of 10 patients each.

INTERVENTIONS

Patients underwent CABG with one of two different methods of myocardial protection and cardiopulmonary bypass. CBC group: intermittent cold blood antegrade-retrograde cardioplegia with moderate hypothermic cardiopulmonary bypass; WBC group: continuous warm blood antegrade-retrograde cardioplegia with mild hypothermic cardiopulmonary bypass.

MAIN OUTCOME MEASURE

The index of oxidative stress used was the alteration of whole blood and plasma glutathione redox status. Samples were collected from the coronary sinus and peripheral vein before anaesthesia (T1), before aortic unclamping (T2), 15 minutes (T3), and 30 minutes (T4) after unclamping. Haemodynamic parameters were measured with thermodilution techniques.

RESULTS

Oxidised glutathione and glutathione-cysteine mixed disulphide significantly increased in the coronary sinus plasma in the CBC group, and the overall redox balance of glutathione was decreased (P < 0.01) at T2-T4 versus T1, and compared with the WBC group. Comparable results were obtained for coronary sinus blood. There was no correlation between postoperative haemodynamic measurements and oxidative stress markers.

CONCLUSIONS

Oxidative stress was significant in patients undergoing CABG using cold blood cardioplegia, while the warm technique minimised the effects of ischaemia. However, oxidative stress was not correlated with myocardial dysfunction following CABG.

The formation of some antigenic epitopes in oxidized human low-density lipoprotein is inhibited by nitric oxide

NO and NO-donors are able to inhibit the peroxidation of polyunsaturated fatty acids in human low-density lipoproteins (LDL) exposed to Cu+2. Here we report that 1-hydroxy-2-oxo-3,3-bis(3-aminoethyl)-1-triazene (NOC-18), a compound which releases NO at low rate in aqueous solutions, powerfully inhibits the peroxidation of polyunsaturated fatty acids, tryptophan loss, the formation of fluorescent aldehydic adducts in apo B100 and the increase of electrophoretic mobility in isolated LDL undergoing oxidation. The inhibitory effect is not restricted to Cu+2-induced peroxidation but is also detectable with other oxidizing conditions such as the free radical generator 2,2'-azobis-(2-amidino propane) hydrochloride (AAPH), the combination of horseradish peroxidase and H2O2 (HRP), and peroxynitrite (ONOO-). The recognition of Cu+2-, AAPH-, and ONOO(-)-modified LDL by specific autoantibodies present in serum of atherosclerotic patients is almost completely inhibited when the oxidation procedure is performed in the presence of NOC-18. However, NOC-18 is completely ineffective in preventing the formation of recognizable antigens in HRP-modified LDL. These findings suggest that NO may efficiently prevent the formation of some, but not all, the antigenic epitopes recognized by human autoantibodies and thus likely formed during in vivo LDL oxidation.

Role of Na+/Ca2+ exchanger in preventing Na+ overload and hepatocyte injury: opposite effects of extracellular and intracellular Ca2+ chelation

We have previously shown that an increase of intracellular Na+ occurs in isolated rat hepatocytes undergoing ATP depletion and that Na+ accumulation is associated with an uncontrolled influx of Ca2+ through the activation in reverse mode of the Na+/Ca2+ exchanger. In the present study we have investigated the relationship between alterations of Na+ and Ca2+ homeostasis and hepatocyte killing using treatments which differentially chelate extracellular or intracellular Ca2+. Chelation of extracellular Ca2+ by ethylene glycol bis-(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) potentiated Na+ overload and cell killing induced in isolated rat hepatocytes by hypoxia or menadione. Similar effects were also observed when Na+ accumulation was induced by the combined addition of Na+ ionophore monensin and the inhibition of plasma membrane Na+/K+ ATPase by ouabain. Conversely, the use of the intracellular Ca2+ chelator EGTA acetoxymethyl ester (EGTA/AM) reduced Na+ overload and hepatocyte death induced by hypoxia or cell treatment with menadione or monensin plus ouabain. The effects of EGTA/AM were reverted in the presence of bepridil, an inhibitor of Na+/Ca2+ exchanger. Altogether these results indicated that differential chelation of intracellular or extracellular Ca2+ influences in opposite ways hepatocyte killing due to ATP depletion by modulating intracellular Na+ levels through the reversed activity of the Na+/Ca2+ exchanger.

Intranuclear distribution, function and fate of glutathione and glutathione-S-conjugate in living rat hepatocytes studied by fluorescence microscopy

The availability of fluorescent probes to detect soluble and protein-bound thiols has made it possible to investigate some aspects of reduced glutathione (GSH) metabolism and function in intact rat hepatocytes and in hepatocyte nuclei. Monochlorobimane (BmCl) has been employed to study the subcellular compartmentation of GSH and the formation and fate of the BmCl-GSH conjugate. The occurrence of relatively high concentrations of GSH within the nuclear matrix has been inferred from fluorescence quantitation using image analysis. Concomitant biochemical studies have revealed the presence of a GSH-stimulated ATP hydrolysis and of an ATP-stimulated GSH accumulation in isolated nuclei, providing the molecular basis for nuclear glutathione compartmentation. The contemporary use of fluorescent probes to label nuclear free sulfhydryl groups, proteins and chromatin status led to the demonstration that intranuclear accumulation of glutathione may modulate the thiol/disulfide redox status of nuclear proteins and control chromatin compacting and decondensation.

Circulating autoantibodies recognizing peroxidase-oxidized low density lipoprotein. Evidence for new antigenic epitopes formed in vivo independently from lipid peroxidation

Oxidatively modified LDLs are antigenic and elicit the generation of autoantibodies often detected in plasma and within plaques of atherosclerotic patients. Although Cu(2+)-oxidized LDL and malondialdehyde (MDA)-modified LDL are usually used as antigens in immunoassays, other, still unrecognized epitopes may be formed in vivo during LDL oxidation and may induce antibody production. Antibodies recognizing LDL oxidatively modified by Cu2+, 2,2'-azobis-(2-amidino propane) hydrochloride (AAPH), and the combination of horseradish peroxidase and H2O2 (HRP) were detected in serum of a group of 90 unselected patients. HRP-oxidized LDL was the antigen that revealed the highest IgG titers, although the extent of LDL oxidation (evaluated as conjugated diene formation, loss of tryptophan fluorescence, production of fluorescent aldehydic adducts, and change in electrophoretic mobility) was comparable to that obtained with Cu2+ and AAPH. There was a highly statistically significant correlation between the IgG titers detected using Cu(2+)- and AAPH-oxidized LDLs as antigens, but no correlation was found between the IgG titers revealed by HRP and Cu2+ or AAPH. In addition, the antibody titers against MDA-modified LDL exhibited a significant correlation with those against Cu(2+)- or AAPH-oxidized LDL but did not correlate with those against HRP-oxidized LDL. Finally, immunocompetition experiments revealed that IgG recognizing HRP-oxidized LDL did not cross-react with Cu(2+)-oxidized LDL and vice versa. The possibility that lipid peroxidation-independent modifications could play a role in HRP-induced formation of antigenic epitopes in LDL was supported by two lines of evidence. First, in probucol-enriched LDL, despite the complete inhibition of lipid peroxidation, HRP, but not Cu2+ and AAPH, was still able to generate epitopes that were recognized by the same sera reacting with HRP-oxidized native (not probucol-enriched) LDL. In addition, the presence of autoantibodies against Cu(2+)- and AAPH-oxidized LDLs was negatively correlated with serum alpha-tocopherol concentration, whereas the titers against HRP-oxidized LDL did not exhibit any statistically relevant correlation with alpha-tocopherol levels. Together, these findings indicate that peroxidase(s)-dependent mechanisms can trigger peculiar lipid peroxidation-independent modifications of LDL in vivo.

Protective effect of dehydroepiandrosterone against copper-induced lipid peroxidation in the rat

This study investigates the effectiveness and multitargeted activity of dehydroepiandrosterone (DHEA) as antioxidant in vivo. A single dose of DHEA was given IP to male rats. Liver and brain microsomes, and plasma low density lipoprotein (LDL), were isolated from rats sacrificed 17 h later. Liver and brain microsomes were challenged with CuSO(4) and, as index of lipid peroxidation, the production of thiobarbituric acid reactive substances (TBARS) was measaured. Also, plasma low-density lipoprotein (LDL) were challenged with copper and the time course of lipid peroxidation was evaluated following the formation of conjugated dienes. The onset of TBARS generation induced by copper was marked delayed in both liver and brain microsomes from DHEA-treated animals. Also, the resistance of LDL to oxidation, expressed by the duration of the lag-phase of the kinetic curve, was significantly enhanced in DHEA-treated rats. Results indicate that in vivo DHEA supplementation makes subcellular fractions isolated from different tissues and plasma constituents (LDL) more resistant to lipid peroxidation triggered by copper. The antioxidant effect on plasma LDL might be of special relevance to the proposed antiatherogenic activity of DHEA. Moreover, multitargeted antioxidant activity of DHEA might protect tissues from oxygen radicals damage.

Hepatic glutathione deficiency in chronic hepatitis C: quantitative evaluation in patients who are HIV positive and HIV negative and correlations with plasmatic and lymphocytic concentrations and with the activity of the liver disease

OBJECTIVES

Reduced glutathione (GSH) is decreased in patients affected by chronic hepatitis C (CHC) as well as in patients who are HIV positive. Because the liver is the most important source of plasmatic GSH, we measured the concentrations of GSH in the liver (H-GSH) of patients with CHC who were either HIV positive or negative, correlating it to the concentrations of GSH in plasma (P-GSH) and in peripheral blood mononuclear cells (PBMCs) (L-GSH), to the replication activity of hepatitis C virus (HCV) in PBMCs, to the activity of the liver disease, and to the state of immunodeficiency in patients who were HIV positive.

METHODS

One hundred, five patients with serologically and histologically demonstrated CHC (55 HIV positive and 50 HIV negative) entered the trial. Fifty-one healthy individuals made up a control group for P-GSH and L-GSH concentrations. H-GSH concentration was determined by high performance liquid chromatography on liver specimens obtained by ultrasound-guided biopsy according to the method described by Reed et al. The concentrations of P-GSH and L-GSH were determined according to the method described by Suarez et al. The detection of HCV RNA strands in PBMCs was performed according to the method described by Qian et al. Histological findings and degree of fibrosis were scored according to the numerical scoring system proposed by Scheuer and by Knodell et al.

RESULTS

H-GSH, P-GSH, and L-GSH were significantly reduced in patients affected by CHC compared with healthy controls (p < 0.001). H-GSH and particularly L-GSH were more significantly reduced in patients who were HIV positive compared with those who were HIV negative (p < 0.001), without significant correlation with the values of the T cell subset CD4+. The reductions in H-GSH, P-GSH, and L-GSH were significantly correlated to the replication activity of HCV in PBMCs (p < 0.001) and to the grade of activity of the liver disease assessed by the values of ALT (p < 0.001) and by histological and fibrosis scores of CHC (p < 0.001). In both groups of patients with CHC, H-GSH, P-GSH, and L-GSH were more reduced in patients addicted to drugs than in patients who were not addicted.

CONCLUSIONS

In patients with CHC, particularly those who are HIV positive, a systemic depletion of GSH is present. This depletion may be a factor underlying the resistance to interferon therapy and, in patients who are HIV positive, to antiretroviral drugs, fostering HCV and/or HIV replication. This may represent the biological basis for GSH replacement therapy.

Carotid intima-media thickening and in vivo LDL oxidation in patients with essential hypertension

Low density lipoproteins (LDL) from hypertensive patients are more prone to in vitro oxidation and undergo a more pronounced oxidation in vivo. Due to the pro-atherogenic activity of oxidatively modified LDL, the correlation between the carotid intima-media thickening (IMT) and the markers of in vivo LDL oxidation was investigated in hypertensive patients. A cross-sectional study on 101 normocholesterolemic patients with newly diagnosed and untreated essential hypertension was performed. The occurrence of in vivo LDL oxidation was evaluated by measuring the titers of autoantibodies against Cu(2+)-oxidised LDL (oxLDL) and malondialdehyde-derivatised LDL (MDA-LDL). The extent and degree of atherosclerosis and the IMT were measured by means of carotid and femoral ultrasonography with a duplex scanner equipped with a high resolution probe. We did not find significant correlations between in vivo LDL oxidation parameters and the extent of atherosclerotic lesion in the entire group of hypertensive patients. However, a significant direct correlation was detected between the carotid IMT and the titer of autoantibodies against both oxLDL and MDA-LDL in hypertensive patients without advanced atherosclerotic plaques. The results obtained support the hypothesis that enhanced LDL oxidation may be one of the pathophysiological events related to the formation and progression of early atherosclerotic lesions (IMT) in carotid arteries of hypertensive patients.

Circulating levels of intercellular adhesion molecule-1 (ICAM-1) and soluble interleukin 2 receptors (IL-2R) in patients with B cell chronic lymphocytic leukaemia

The serum concentrations of circulating ICAM-1 (cICAM-1) and soluble receptors for interleukin-2 (sIL-2R) were evaluated on 48 patients with B-cell chronic lymphocytic leukaemia (B-CLL) and on 15 healthy control subjects. The mean +/- SD concentration of cICAM-1 was significantly higher (p < 0.002) in B-CLL patients (407.7 +/- 164.3 ng/ml) than in healthy controls (245.4 +/- 76.7 ng/ml). Patients with progressive disease had higher cICAM-1 levels than patients with "indolent" disease (440.38 +/- 32.3 ng/ml versus 321.36 +/- 14.45 ng/ml; p < 0.0001). Serum levels of cICAM-1 were also significantly higher (p < 0.0002) in patients with advanced stage (III-IV) than in those with early stage (I-II). The increase of cICAM-1 levels was positively correlated to increases of soluble receptors for interleukin-2 (r = 0.9; p < 0.0001). These results seem to show that the measurement of serum levels of cICAM-1 may be an useful tool for monitoring disease activity and tumoral mass in patients with B-CLL. However, further studies are needed to define the functional role of high cICAM-1 levels in the immunological dysregulation of patients with malignancy.

Protective effects of carvedilol, a vasodilating beta-adrenoceptor blocker, against in vivo low density lipoprotein oxidation in essential hypertension

Low density lipoprotein (LDL) oxidation plays a crucial role in the development and progression of atherosclerosis and is enhanced in patients with essential hypertension. This finding has stimulated a search for antihypertensive drugs with high intrinsic antioxidant properties. We investigated the antihypertensive and antioxidant effects of carvedilol, a new vasodilating beta-adrenoceptor blocking agent in a group of patients with mild to moderate essential hypertension after 4-month treatment. Carvedilol administration markedly increased the resistance to oxidation of LDL isolated from treated patients to values comparable to those of control, nonhypertensive subjects. This effect was achieved despite a significant loss in LDL-associated vitamin E. The increased resistance of LDL to oxidation promoted by carvedilol was not related to the normalization of previously increased blood pressure (BP). Indeed, the administration of other conventional antihypertensive drugs, capable of decreasing arterial BP but without high intrinsic antioxidant properties, to a control group of matched hypertensive patients failed to ameliorate LDL oxidation parameters. Carvedilol treatment also reduced the extent of in vivo LDL oxidation, as reflected by the decrease in antioxidized LDL autoantibody titer. This effect as well was detected only in the group of carvedilol-treated hypertensive patients and not after the simple reduction in BP obtained with antihypertensive drugs different from carvedilol.